U.S. patent application number 10/898491 was filed with the patent office on 2005-02-17 for method for reducing exhaust carbon dioxide.
This patent application is currently assigned to NKK CORPORATION. Invention is credited to Isoo, Tsuneo, Kato, Makoto, Takahashi, Tatsuhito, Tanabe, Haruyoshi.
Application Number | 20050036932 10/898491 |
Document ID | / |
Family ID | 26470538 |
Filed Date | 2005-02-17 |
United States Patent
Application |
20050036932 |
Kind Code |
A1 |
Takahashi, Tatsuhito ; et
al. |
February 17, 2005 |
Method for reducing exhaust carbon dioxide
Abstract
A method for effectively absorbing and removing CO.sub.2 in an
exhaust gas generated during an industrial process for reducing the
amount of CO.sub.2 that is exhausted into the atmosphere. The
exhaust gas containing CO.sub.2 is blown into an agglomerate of
solid particles containing CaO and/or Ca(OH).sub.2 so that the
CO.sub.2 is in contact with the agglomerate for fixing the CO.sub.2
in the exhaust gas as CaCO.sub.3, thereby reducing the CO.sub.2
concentration in the exhaust gas. Preferably, the solid particles
contain water, and more preferably, the solid particles contain
surface adhesive water.
Inventors: |
Takahashi, Tatsuhito;
(Fukuyama, JP) ; Isoo, Tsuneo; (Fukuyama, JP)
; Kato, Makoto; (Fukuyama, JP) ; Tanabe,
Haruyoshi; (Fukuyama, JP) |
Correspondence
Address: |
FRISHAUF, HOLTZ, GOODMAN & CHICK, PC
767 THIRD AVENUE
25TH FLOOR
NEW YORK
NY
10017-2023
US
|
Assignee: |
NKK CORPORATION
Tokyo
JP
|
Family ID: |
26470538 |
Appl. No.: |
10/898491 |
Filed: |
July 22, 2004 |
Related U.S. Patent Documents
|
|
|
|
|
|
Application
Number |
Filing Date |
Patent Number |
|
|
10898491 |
Jul 22, 2004 |
|
|
|
09844533 |
Apr 27, 2001 |
|
|
|
09844533 |
Apr 27, 2001 |
|
|
|
PCT/JP99/05972 |
Oct 28, 1999 |
|
|
|
Current U.S.
Class: |
423/432 |
Current CPC
Class: |
Y02C 20/40 20200801;
B01D 2251/604 20130101; B01D 2257/504 20130101; B01D 2251/404
20130101; Y02P 20/151 20151101; C01F 11/18 20130101; A01G 33/00
20130101; B01D 53/62 20130101; Y02A 20/402 20180101; Y02P 60/20
20151101 |
Class at
Publication: |
423/432 |
International
Class: |
C01F 011/18 |
Foreign Application Data
Date |
Code |
Application Number |
Oct 29, 1998 |
JP |
10-324472 |
May 18, 1999 |
JP |
11-137113 |
Claims
What is claimed is:
1. A method for reducing an exhaust carbon dioxide comprising:
preparing agglomerates of solid particles containing at least one
compound selected from the group consisting of CaO and
Ca(OH).sub.2; contacting an exhaust gas containing CO.sub.2 with
the agglomerates of the solid particles in a reaction chamber, the
solid particles having a film of adhesive water on a surface of the
solid particles; and fixing CO.sub.2 in the exhaust gas as
CaCO.sub.3 in the solid particles to reduce CO.sub.2 in the exhaust
gas.
2. The method according to claim 1, wherein the agglomerates of the
solid particles are obtained by pulverizing materials containing
CaO and/or Ca(OH).sub.2 into grain and/or rough grain.
3. The method according to claim 1, wherein the step of contacting
the exhaust gas comprises contacting an exhaust gas containing
CO.sub.2 with the agglomerates of the solid particles by blowing
the exhaust gas into the agglomerates of the solid particles.
4. The method according to claim 3, wherein the exhaust gas
containing CO.sub.2 is blown into the agglomerates of the solid
particles from one direction.
5. The method according to claim 1, wherein the water content in
the agglomerates of the solid particles is from 3 wt. % to 20 wt.
%.
6. The method according to claim 1, wherein a grain size of the
solid particles is substantially 5 mm or less.
7. The method according to claim 1, wherein the exhaust gas
introduced into the reaction chamber is at a temperature
corresponding to the boiling point of water or lower, within the
reaction chamber.
8. The method according to claim 1, wherein the reaction chamber is
at a temperature corresponding to the boiling point of water or
lower.
9. The method according to claim 1, wherein a temperature of the
agglomerates of the solid particles is at a temperature
corresponding to the boiling point of water or lower, within the
reaction chamber.
10. The method according to claim 1, wherein the step of contacting
the exhaust gas containing CO.sub.2 with the agglomerates of the
solid particles comprises contacting a pressurized exhaust gas with
the agglomerates of the solid particles.
11. The method according to claim 1, further comprising saturating
H.sub.2O in the exhaust gas, prior to contacting the exhaust gas
with the agglomerates of the solid particles.
12. The method according to claim 1, wherein the water content in
the agglomerates of the solid particles is a range of from 3 to 20
wt. %, and the exhaust gas is blown into the agglomerates of the
solid particles, to contact the exhaust gas with the agglomerates
of the solid particles.
13. The method according to claim 12, wherein the exhaust gas
introduced into the reaction chamber is at a temperature
corresponding to the boiling point of water or lower, within the
reaction chamber, the reaction chamber is at a temperature
corresponding to the boiling point of water or lower, and the
agglomerates of the solid particles to be contacted with the
exhaust gas is at a temperature corresponding to the boiling point
of water or lower, within the reaction chamber.
14. The method according to claim 13, further comprising saturating
H.sub.2O in the exhaust gas prior to contacting the exhaust gas
with the agglomerates of the solid particles.
15. The method according to claim 1, wherein the agglomerates of
the solid particles are at least one material selected from the
group consisting of a slag generated in an iron and steel making
process and a concrete.
16. The method according to claim 1, wherein the solid particles of
the agglomerates are at least one material selected from the group
consisting of a slag generated in an iron and steel making process
and a concrete.
17. The method according to claim 1, wherein the agglomerates of
the solid particles are at least one material selected from the
group consisting of a slag generated in an iron-steel making
process, a concrete, a mortar, a glass, an alumna cement and a CaO
containing refractory.
18. A method of creating a seaweed bed comprising: temporarily
immersing a heavy material in an existing seaweed bed so that
marine algae adhere and grow on a surface of the material;
recovering the heavy material and transporting the heavy material
as a seed material in a place for creating the seaweed bed; and
arranging an adhering material for adhering the marine algae around
the seed material so that the marine algae on the seed material is
proliferated onto another seed material.
Description
CROSS REFERENCE TO RELATED APPLICATIONS
[0001] This application is a divisional application of application
Ser. No. 09/844,533 filed on Apr. 27, 2001, which is a continuation
application of International application No. PCT/JP99/05972(not
published in English), filed on 28 Oct. 1999, the entire contents
of which are incorporated by reference herein.
FIELD OF THE INVENTION
[0002] The present invention relates to a method for reducing
CO.sub.2 concentration in exhaust gas generated in an industrial
process and others, and reducing the amount of exhausting CO.sub.2
in an atmospheric air. Further, the present invention relates to a
water immersion block for seaweed and algae planting places, fish
gathering rocky places or riverbeds, and a method for making the
same. Herein, the above mentioned "seaweed and algae planting
places" designate groups or communities of marine algae (algae,
seaweed and the like) growing in the sea bottom.
BACKGROUND OF THE INVENTION
[0003] Recently, from the viewpoint of preventing world warming, it
has been demanded to reduce the amount of generated CO.sub.2 on a
global scale. At the congress of the world warming prevention which
took place at Kyoto in December 1997, a protocol for the reduction
of the exhaust gas was adopted. This protocol established a
reduction target in 2010, aiming at reducing at least 5% of a
standard with respect of 1990 of the exhaust amounts of greenhouse
effect gases (CO.sub.2, CH.sub.4, N.sub.2O and others) of all
advanced countries. In accordance with the protocol, Japan has been
assigned a duty of lowering 6% of the amount of issuing exhaust
gases.
[0004] CO.sub.2 accounts for 64% of the contribution degree per the
greenhouse effect gas with respect to world warming, and is mainly
exhausted by using fossil fuel. In Japan, 95% of the greenhouse
effect gas generated by social or economical activities is
CO.sub.2, and more than 90% thereof is accompanied with use of
energy. Accordingly, a measure for preventing the world from
warming will be to chiefly control CO.sub.2 exhausted in
conjunction with the use of energy.
[0005] With respect to the control of exhausting CO.sub.2
accompanied with the use of energy, for example, the iron and steel
business world which accounts for about 11% of the final energy
consumption of Japan, projects a self-imposed behavior plan toward
2010, and proclaims in this plan a 10% reduction, in comparison
with 1990 of the energy consumption in the production process in
2010. Further, as an actual measure thereto other than energy
reduction, included are the blowing of waste plastics as reducing
agents into blast furnaces, usage of non-used energy in neighboring
areas, or contribution to energy saving by making products or
by-products.
[0006] However, in the present high degree industrialized society,
there is per se a limit in the control of using energy which is
related to the cutting of the exhaust of CO.sub.2, and it is not
always easy to accomplish a target of cutting CO.sub.2 exhaust only
with the control of the amount of energy used.
[0007] Accordingly for accomplishing the target of cutting CO.sub.2
exhaust, it is considered to be necessary to take such a measure
from both sides of cutting the CO.sub.2 generated amount, as well
as removing CO.sub.2 from the generated gas (exhaust gas). However,
an effective method which removes CO.sub.2 from the exhaust gas on
an industrial scale is not yet conventionally known.
[0008] As a part of usefully using slag generated in the iron and
steel making process, it has been tried to make use of the slag as
a seawater immersion block for algae planting places or fish
gathering rocky places.
[0009] As main embodiments of utilizing slag as such materials,
there is a method of utilizing massive slag for algae planting
places as it is, and another method of utilizing slag as
agglomerates for fish gathering rocky places. However these methods
are involved with problems as discussed herein.
[0010] In the former method, Ca content contained in slag is
dissolved into the sea to probably heighten the pH in the
neighboring seawater. The obtained massive slag in the iron-steel
making process is suited as a block for such as algae planting
places due to surface properties in comparison with concrete
products. However, as a block for the algae planting places, the
massive slag has functions (adhering property of sea algae or
rearing property) only of a similar degree to a natural block, and
does not have a special function of accelerating the growing of sea
algae.
[0011] The slag generated in the iron-steel making process contains
much iron content such as metals (grain iron), and ordinarily it is
broken to desired sizes for recovering the iron content in the slag
for recycle in the iron-steel making process. Slag for algae
planting places necessitates sizes of a certain degree, and slag
broken for recovering the metal is scarcely used. If use is made of
the massive slag as a block for algae planting places, the recovery
of the metal useful as iron and steel sources can hardly be
practiced.
[0012] In contrast, if massive slag containing much metal is
immersed into the sea as it is for use as a block in algae planting
places, the iron content in the slag is oxidized, depending on sea
areas, to cause a shortage of oxygen in the seawater, and further
by dissolution of the iron content; the iron content might be
excessively supplied in the sea water. For avoiding such problems,
the metal in the slag should be perfectly removed. Since the slag
content and the metal generally exist in a mixture as if entwined,
the slag must be more finely pulverized than the case of the above
mentioned metal recovery in order to completely remove the metal.
Such finely pulverized slag cannot be used as materials to be
immersed in the sea water for the algae planting places.
[0013] On the other hand, the latter method uses slag as an
agglomerate of a concrete made pre-cast body, and so there seldom
occurs a problem of the case that the massive slag is immersed in
the sea as it is. However materials available by this method are
concrete products whose surfaces are composed of cement mortar, and
which therefore cannot exhibit even the properties of massive slag
(for example, uneven surface property) which are expected to
display performance per se as for algae planting places.
[0014] Recently, there has arisen a tendency towards maintenance
and improvement of natural circumstances of rivers including living
circumstances of creatures such as fishes or shells, and as a part
of the tendency, for example, it has been tried to repair riverbeds
to be suited to water living creatures (fishes, shells, water
insects and others) or water plants (algae, water grass and others)
to inhabit and live. In the rivers, creatures' living and resting
spaces called biotopes are created with blocks and, accordingly,
much uneven riverbeds made by blocks are better for water living
creatures. Relatively large spaces among immersed or half-immersed
massive blocks on the riverbeds or small spaces among small blocks
laid thereon are important living spaces (biotopes) for water
living creatures. Blocks on the riverbeds are also places for water
plants to live, and for rearing water plants. Blocks are therefore
important.
[0015] For repairing riverbeds as a part of maintenance or
improvement of the natural circumstances of rivers, the sinking or
laying of blocks in appropriate forms (for example, placing of
large massive blocks, sinking or laying of middle massive or small
blocks on the riverbeds) may be a useful means for arranging the
circumstances for fish to live or inhabit. For repairing riverbeds,
enormous amount of blocks are required. It probably causes
destruction of nature to supply natural blocks from other places,
and since natural blocks are not cheap, the construction cost is
increased.
[0016] For usefully using slag generated in the iron and steel
making process, it has been tried to utilize slag as sea water
immersion blocks for fish gathering rocky places. Concerning blocks
for sinking in rivers, slag generated in the iron and steel-making
process should be considered.
[0017] As discussed hereinabove, with respect of main embodiments
for utilizing slag to be immersed in rivers, there is considered a
method of using the slag as it is as an immersion block and another
method of using the slag as concrete pre-cast agglomerates.
[0018] However these methods have problems as discussed
hereinabove.
[0019] In the former method, the Ca content in the slag is
dissolved into the water to probably heighten the pH in the river
water. Since the slag generated in the iron and steel making
process contains much metal (grain iron), if massive slag is
immersed in the water as it is, grain iron is oxidized, and
depending on water ranges, a shortage in oxygen might occur in
neighboring rivers. For avoiding such problems, the metal in the
slag should be completely removed. Since the slag content and the
metal generally exist in a mixture as if entwined, the slag must be
more finely pulverized than in the case of the above mentioned
metal recovery in order to completely remove the metal. Such finely
pulverized slag cannot be used as materials to be immersed in the
sea water for algae planting places.
[0020] On the other hand, as in the latter method, if the slag is
used as an agglomerate of a concrete made pre-cast body, since the
base is made of concrete, the properties of the massive slag (for
example, uneven surface property) which are expected to display
performance as an immersion block in the rivers cannot be
displayed. The concrete has a high pH (ordinarily, about a pH of 12
to 12.5), so that it increases the pH in the neighboring river
water or delays growth of algae.
[0021] It has recently been recognized to prepare fish ways for
fishes to move to upstream or downstream or to go up in dams or
barrages, and repairs therefore have been carried out. The fish way
is provided with a waterway (usually, having a width of about 2 to
5 m) for forming flows for fish to move in parts of the dam or
barrage, and known are slant paths or stepwise paths.
Conventionally ordinary fish ways are made by cutting parts of the
dam or barrage in the water path encircled with the concrete.
[0022] Thus, the conventional fish way has no obstacle for fish to
move as long as no problems exist in water flowing speed, water
bottom obliquity or steps. However, since the concrete-made fish
way has a smooth bottom, it is difficult for water living creatures
such as algae to live, and there are problems for water living
plants (for example, crusts or water living insects) relating to
moving because of the catching with their claws on the riverbed
(surface projections as a block for water living plants). For these
problems, there is a method of structuring the fish way with a foam
concrete to make fine indentations on the bottom of the fish way,
however the construction cost is high with less practicability. In
either way, the concrete has a high pH, which is not preferable for
water living creatures moving on the riverbed.
[0023] Algae planting places are for breeding sea living plants and
creatures in coastal and sea areas, and are indispensable as living
places for useful fish and shellfish, rearing marine algae, laying
eggs of fish and shellfish, breeding fry and small fish, or
baiting. In addition, recently, nitrogen or phosphorus in the
seawater are taken in by marine algae or other living creatures
through the food cycle or chain in the algae planting places,
otherwise suspension materials subside in the algae planting
places. Thus, a water purifying action has been noticed.
[0024] However, nowadays, the algae planting places continue to
rapidly fade or decline by influences of reclaiming coasts or
corruption of the seawater. In particular, recently, in many
coastal or sea areas, a big problem of so-called "shore burn"
phenomena occurs. It has therefore been demanded to establish an
algae place creation act for recovering algae planting places.
[0025] Algae creating methods conventionally carried out are
roughly divided in the following two ways.
[0026] (1) At places where algae planting places are desired, bases
for rearing marine algae (mainly, natural blocks or concrete
blocks) are laid, and seeds and saplings of marine algae or mother
algae are transplanted, and managed for rearing them as
required.
[0027] (2) Places environmentally easy to become algae living
places, that is, such places suitable for creating the algae places
in view of circumstances as water depth, water quality or ocean
current, which are within reach of spores of marine algae from
existing algae places, are selected, and the bases are laid there.
Algae places are thus created which are maintenance free
(transplanting or rearing managing are not basically done).
[0028] Of these methods, the method (1) is advantageous in wide
selecting ranges for creating the algae places, however, basically
all of the creations are artificial, and it is necessary to fully
manage taking-roots or rearing of transplanted seeds and saplings,
for which a lot of time and tremendous cost are taken. This method
is absolutely unsuited to large scale creations of algae
places.
[0029] On the other hand, as the method (2) creates algae places
which are maintenance free, other than laying the bases, it is
advantageous in that it takes less time and cost, in comparison
with the method (1). However, this method is short with respect of
general purpose uses because of limited places to become algae
places. According to a certain report for creating an algae place
by the method (2), at a proper period in a place which does not
naturally become an algae place, it is preferable to select a place
within 100 m from an existing algae place, taking into
consideration the reach of spores or seeds from existing algae
places. Accordingly, it is assumed that this method is difficult to
create algae places at places where circumferentially whole algae
places have been faded by shore burn.
SUMMARY OF THE INVENTION
[0030] It is a first object of the invention to provide a method
that effectively absorbs and removes CO.sub.2 in an exhaust gas
generated in an industrial process for reducing an amount of
exhausting CO.sub.2 into the atmospheric air.
[0031] The inventors made detailed investigations on materials of
absorbing CO.sub.2 and a method of using the same in order to find
a method which effectively absorbs and removes CO.sub.2 in the
exhaust gas on an industrial scale. As a result, they found that as
the CO.sub.2 absorbing material, optimum was an agglomerate of
solid particles containing CaO such as slag or concrete. The
inventors also found that by blowing exhaust gas containing
CO.sub.2 in an agglomerate of the solid particles to be in contact
with the exhaust gas, and especially preferably by blowing the
exhaust gas, under the condition that the gas dissolves into the
suitable amount of water content and the successive reaction (more
preferably, surface adhesive water of the solid particles) to
contact with the exhaust gas, it was possible to fix CO.sub.2 in
the exhaust gas as CaCO.sub.3 in the solid particles and
effectively absorb and remove CO.sub.2.
[0032] The present invention has been realized on the
above-mentioned findings and is described as follows.
[0033] [1] A method for reducing an exhaust carbon dioxide
comprising the steps of:
[0034] preparing agglomerates of solid particles containing at
least one compound selected from the group consisting of CaO and
Ca(OH).sub.2;
[0035] contacting an exhaust gas containing CO.sub.2 with the
agglomerates of the solid particles in a reaction chamber, the
solid particles having a film of adhesive water on a surface of the
solid particles;
[0036] fixing CO.sub.2 in the exhaust gas as CaCO.sub.3 to reduce
CO.sub.2 in the exhaust gas.
[0037] [2] The method according to [1], wherein the agglomerates of
the solid particles are obtained by pulverizing materials
containing CaO and/or Ca(OH).sub.2 into grain and/or rough
grain.
[0038] [3] The method according to [1] or [2], wherein the step of
contacting the exhaust gas comprises contacting by blowing the
exhaust gas into the agglomerates of the solid particles.
[0039] [4] The method according to [3], wherein the exhaust gas
containing CO.sub.2 is blown into the agglomerates of the solid
particles from one direction.
[0040] [5] The method according to [1]-[4], wherein the water
content in the agglomerates of the solid particles is from 3% to
20%.
[0041] [6] The method according to [1]-[5], wherein a grain size Of
the solid particles is substantially 5 mm or less.
[0042] [7] The method according to [1]-[6], wherein the temperature
of the exhaust gas to be introduced into the reaction chamber is at
the boiling point of water or lower within the reaction
chamber.
[0043] [8] The method according to [1]-[7], wherein the temperature
in the reaction chamber is at the boiling point of water or
lower.
[0044] [9] The method according to [1]-[8], wherein the temperature
of the agglomerates of the solid particles is the boiling point of
water or lower within the reaction chamber.
[0045] [10] The method according to [1]-[9], wherein the step of
contacting the exhaust gas containing CO.sub.2 with the
agglomerates of the solid particles comprises contacting a
pressurized exhaust gas with the agglomerates of the solid
particles.
[0046] [11] The method according to [1]-[10], further comprising
the step of saturating H.sub.2O in the exhaust gas, prior to
contacting the exhaust gas with the agglomerates of the solid
particles.
[0047] [12] The method according to [1]-[11], wherein the
agglomerates of the solid particles are at least one selected from
the group consisting of a slag generated in an iron-steel making
process and a concrete.
[0048] [13] The method according to [1]-[11], wherein the solid
particles of the agglomerates are at least one selected from the
group consisting of a slag generated in an iron-steel making
process and a concrete.
[0049] [14] The method according to [1]-[11], wherein the
agglomerates of the solid particles are at least one selected from
the group consisting of a slag generated in an iron-steel making
process, a concrete, a mortar, a glass, an alumna cement, and a CaO
containing refractory.
[0050] In the invention, CaO and Ca(OH).sub.2 contained in the
solid particles are sufficient with those contained as at least one
part of the composition of the solid particles, and accordingly,
concerning other than CaO and Ca(OH).sub.2 as mineral, there are
also included those existing in the solid particles as one part of
the composition such as 2CaO.SiO.sub.2, 3CaO.SiO.sub.2 or
glass.
[0051] It is a second object of the present invention to provide a
water immersion block. The immersion block is excellent for rearing
algae and breeding fish and shellfish without heightening the pH in
seawater or river water. The present invention also provides a
method of making the same, and a further method of building an
algae planting place using a water immersion block.
[0052] For accomplishing the above-mentioned object, the present
invention provides a water immersion block for immersion in water
made by a method comprising the steps of:
[0053] preparing a mixture comprising grain like slag generated in
an iron-steel making process; and
[0054] introducing carbonation to said mixture to generate a
carbonized substance, and making the mixture massive with a binder
of the generated carbonized substance.
[0055] Blocks made by this method for sinking in the water may be
used in seawater or in the fresh water of rivers.
[0056] The grain like slag may be at least one selected from the
group consisting of grain like slag, rough grain like slag and
small massive slag, otherwise the slag may be grain like or rough
grain like slag having been passed through a metal removing
treatment.
[0057] Further, the invention provides a method of making immersion
blocks for immersion in water comprising the steps of:
[0058] preparing a mixture composed of grain like slag generated in
the iron-steel making process;
[0059] forming layers filled up with said mixture; and
[0060] causing a carbonation reaction in the mixture in a packed
bed by using carbon dioxide so as to make the mixture massive.
[0061] The step of forming the packed bed may depend on forming
mountains by piling the mixture.
[0062] The invention provides a method of building algae planting
places comprising the steps of:
[0063] temporarily sinking weighty materials on existing algae
planting places, and planting to rear marine algae on the surface
of the weighty materials;
[0064] recovering the weighty materials and moving them as seeding
materials to places for planting algae; and
[0065] arranging other materials for planting marine algae around
the seeding materials and increasing the marine algae on the
seeding material onto other seeding materials.
[0066] The above mentioned steps are only one example, and may not
necessarily follow the above method.
BRIEF DESCRIPTION OF THE DRAWINGS
[0067] FIG. 1 is a schematic drawing assuming a mechanism that
CO.sub.2 in the exhaust gas is absorbed and fixed on the surface of
the solid particle containing CaO.
[0068] FIG. 2 is a schematic drawing showing one embodiment of the
inventive method using a fluidized bed of the agglomerate of solid
particles.
[0069] FIG. 3 is a schematic drawing showing one embodiment of the
inventive method using a rotary kiln.
[0070] FIG. 4 is a schematic drawing showing one embodiment of the
inventive method, wherein CO.sub.2 containing gas is blown from one
direction into the packed bed of the agglomerate of solid
particles.
[0071] FIG. 5 is a schematic drawing showing a method according to
the present invention of making a seawater immersion block.
[0072] FIG. 6 is a schematic drawing showing an actual example of
the method of FIG. 5.
[0073] FIG. 7 is a schematic drawing showing another method
according to the present invention of making a seawater immersion
block.
[0074] FIG. 8 is a schematic drawing showing an actual example of
the method of FIG. 7.
[0075] FIGS. 9A, 9B and 9C are schematic drawings showing
structural examples where river water immersion blocks are laid or
built on artificial structural parts or artificial riverbeds, such
as a fish way.
[0076] FIG. 10 is a schematic drawing showing a method of making a
river water immersion block according to the present invention.
[0077] FIG. 11 is a schematic drawing showing an actual example of
a method of making a river water immersion block according to the
present invention.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0078] A first embodiment for carrying out the present invention is
as follows. Namely, the first embodiment uses, as a CO.sub.2
absorbing material, the agglomerate of solid particles containing
CaO and/or Ca(OH).sub.2 such as slag or concrete, CO.sub.2 in the
exhaust gas is absorbed and removed by means of contacting the
CO.sub.2 containing exhaust gas with the agglomerate of solid
particles for fixing CO.sub.2 in the exhaust gas as CaCO.sub.3 in
the solid particles by the following reaction. In this embodiment,
as a method for contacting the exhaust gas, it is preferable to
blow the exhaust gas into the agglomerate of solid particles, and
more preferable to blow the exhaust gas from one direction. The
exhaust gas can be blown from an upper side, from a lateral side
and from a lower side. However, blowing from the lower side is
easier to handle this method.
CaO (solid particles)+CO.sub.2 (exhaust gas ).fwdarw.CaCO.sub.3
(solid particles)
[0079] Conventionally, the agglomerate of solid particles
containing CaO as slag is hardened by a carbonation reaction with
CO.sub.2, and employs the hardened material for architectural or
civil engineering. The present invention utilizes the carbonation
reaction between CO.sub.2 and the agglomerate of CaO containing
solid particles for reducing CO.sub.2 in the exhaust gas, which is
quite a novel concept in contrast to the prior art. The method of
the present invention has been established especially for reducing
carbon dioxide.
[0080] In the first embodiment, the agglomerates of the solid
particles containing CaO are used. The agglomerates of the solid
particles are contacted with the exhaust gas containing CO.sub.2.
CO.sub.2 in the exhaust gas is fixed as CaCO.sub.3 with the solid
particles. In the first embodiment, it is preferable to contact the
exhaust gas with the solid particles through an appropriate amount
of the water content contained in the solid particles. It is more
preferable to contact the exhaust gas with the solid particles
under the condition where the water is adhered to the surface of
the solid particles (water film). The above-mentioned contacting
methods make it possible to effectively heighten the absorbing rate
of CO.sub.2 in the exhaust gas by the solid particles. Therefore,
in the first embodiment, it is preferable that the main solid
particle comprising the agglomerate of the solid particle contains
water, and it is more preferable to have surface adhesive
water.
[0081] In the above-mentioned preferable embodiment, especially in
case that the solid particle contains surface adhesive water, the
reaction is as follows. That is to say, the reaction is between
CO.sub.2 in the exhaust gas and the solid particle. In other words,
the reaction is between a Ca component (Ca ion) dissolving
(diffusion) into the surface adhesive water from the solid particle
and carbon dioxide component dissolved into the water content
adhered on the surface out of the exhaust gas. It was found that
the reaction with CO.sub.2 in the surface adhesive water of the
solid particle was especially effective for absorbing and fixing
CO.sub.2.
[0082] At first, the inventors considered that in a method of
reacting CO.sub.2 in an exhaust gas with Ca in solid particles for
fixing CO.sub.2 as CaCO.sub.3 in the solid particles, CaCO.sub.3
would be precipitated on the whole surface of the solid particles
as the reaction progressed, and as a result of preventing the
diffusion of Ca ions from the solid particles, a CO.sub.2 absorbing
efficiency of a high level to be practiced on an industrial scale
could not be expected. However, absolutely contrary to their
expectations, it was found that if the reaction with CO.sub.2 was
carried out under the condition where the water content existed in
the solid particles, in particular under the condition where the
water was adhered to the surface of the solid particles, CO.sub.2
could be absorbed at an extremely high efficiency. The reasons
therefore are not clear, however, the following reasons may
apply.
[0083] FIG. 1 is a schematic view, which assumes a mechanism of
absorbing and fixing CO.sub.2 in the exhaust gas in the surface of
the solid particles. As seen in FIG. 1, under the condition where
adhesive water exists on the surface of the solid particles
containing CaO, Ca ions are dissolved from the solid particles into
the surface adhesive water, while CO.sub.2 (carbon ions) is
dissolved from the exhaust gas into the surface adhesive water,
respectively. Both of Ca ions and carbon ions react in the surface
adhesive water. Furthermore, CaCO.sub.3 is precipitated mainly in
the surface of the solid particles. When precipitating, the
precipitating nucleus of CaCO.sub.3 is not uniformly generated in
water, nucleus of CaCO.sub.3 is not uniformly generated in water,
however, it is generated as a non-uniform nucleus which is easily
generated in the surface of the solid particles. Therefore, the
precipitation of CaCO.sub.3 and growth thereafter occurs merely in
the specific area on the surface of the solid particles.
Consequently, it is considered that there can exist, at a
considerable proportion, a surface area of the solid particles
where neither precipitation nor growth of CaCO.sub.3 takes place.
Since it is possible to maintain the supply (dissolution) of Ca
ions in the surface adhesive water of the solid particles, CO.sub.2
can be effectively absorbed and fixed in a short period.
[0084] Further reference will be made to the preferable embodiment
of the invention.
[0085] The present embodiment uses, as the CO.sub.2 absorbing
material, an agglomerate of solid particles containing CaO and/or
Ca(OH).sub.2 as the composition. Ca(OH).sub.2 contained in the
solid particles also reacts with CO.sub.2 similarly to CaO. Since
it can be fixed as CaCO.sub.3, the solid particles may contain
Ca(OH).sub.2. As mentioned above, CaO and Ca(OH).sub.2 contained in
the solid particles are sufficient with such substances contained
as a part of the composition of at least the solid particle, and
therefore, substances other than CaO and Ca(OH).sub.2 as minerals
are included which exist in the solid particles as parts of the
composition such as 2CaO.SiO.sub.2, 3CaO.SiO.sub.2 or glass.
[0086] As such solid particles, in particular concrete containing
much CaO (and/or Ca(OH).sub.2) or slag generated in the iron-steel
making process are desirable. Reference will be made in detail
later therefore.
[0087] Grain sizes of the solid particles are not especially
limited, however the grain sizes which are as small as possible are
preferable for securing to contact areas with the exhaust gas and
increasing reactivity, specifically substantially 5 mm or lower
(excepting solid particles of a large size inevitably included), in
particular preferably 1 mm or less. Actually, it is preferable that
grains of 5 mm or less occupy 90% or more.
[0088] As mentioned above, for securing the reactivity between the
solid particles and CO.sub.2 in the exhaust gas in the exemplified
method, it is preferable that the main solid particles contacting
the exhaust gas contain the appropriate amount of water. It is more
desirable that the main solid particles contacting the exhaust gas
have the surface adhesive water thereof. Surface adhesive water
means the water content existing together with the solid particles
and the water existing in the outer surface of the solid particles,
except the water content contained within the grains. Preferably,
the percentage of water content in the agglomerate of the solid
particles is 3 to 20% from a similar viewpoint. Thus, for
maintaining the water content of the solid particles and the
agglomerate thereof, the water content is, as needed, previously
added to the agglomerate of the solid particles.
[0089] The CO.sub.2 containing exhaust gas to be contacted with the
agglomerate of solid particles heightens reactivity with the solid
particles by increasing the temperature thereof, to some extent.
However, if the temperature of the exhaust gas to be introduced
into the space (called as "reaction space" hereinafter) for
contacting with the agglomerate of solid particles exceeds the
boiling point of water supported in the reaction space, it
evaporates the surface adhesive water of the solid particles, and
hinders the reactivity. Therefore, it is preferable that the
temperature of the exhaust gas is set to be at the boiling point of
water or lower in the reaction space. Also for the same reason,
preferably the temperature within the reaction space is kept at the
boiling point of water or lower and, in addition, the temperature
of the agglomerate of solid particles is also kept at the boiling
point of water or lower within the reaction space.
[0090] From a similar viewpoint, it is preferable to have a higher
concentration of steam in the exhaust gas, and so, it is desirable
that H.sub.2O is saturated by an instrument by previously passing
the exhaust gas in water, and subsequently the exhaust gas is
contacted with the agglomerate of solid particles.
[0091] As the agglomerate of solid particles to be the CO.sub.2
absorbing material, as far as being the agglomerate of solid
particles containing CaO and/or Ca(OH).sub.2, no limit is provided,
however in particular, in points that the containing rate of CaO
(and/or Ca(OH).sub.2) is high and a recycle of materials is
available, slag generated in the iron-steel making process, and
concrete (for example, waste concrete) are desirable. Accordingly,
preferably, at least one part of the solid particle comprising the
agglomerate of solid particles is slag and/or concrete and, as is
especially desirable, the main solid particles are slag and/or
concrete.
[0092] As the agglomerate of solid particles to be the CO.sub.2
absorbing material, other than slag and concrete, there may be
listed mortar, glass, alumina cement, CaO containing refractory, or
MgO containing with refractory, and one kind or more of the
agglomerate of solid particles may be singly mixed, otherwise mixed
with slag and/or concrete.
[0093] The agglomerate of solid particles has a better reactivity
with CO.sub.2 if the weight ratio (basicity) of CaO to SiO.sub.2 is
high, and from this viewpoint, it is preferable that CaO/SiO.sub.2
is 1.2 or higher and, desirably, 1.5 or higher.
[0094] In general, the composition of CaO in the slag generated in
the iron-steel making process is about 13 to 55 wt. %, and the
composition of CaO in the concrete (e.g. waste concrete) is about 5
to 15 wt. % (the CaO composition in the cement: 50 to 60 wt. %),
and being easily available, they are well-suited materials as the
solid particles to be the CO.sub.2 absorbing material.
[0095] As slag generated in the iron-steel making process, there
may be enumerated slags from blast furnaces such as a slow cooling
slag or a water granulated slag therefrom, which means slags from
the iron-steel making process such as dephosphorized slag,
desulfurized slag, desiliconized slag, decarburized slag or casting
slag generated in pre-treatments, converter or casting slags from
iron ore reduction; or slags from electric furnaces. However, there
is no limit to the types of slags. Slag mixtures of two kinds or
more may be used.
[0096] Slag generated in the iron-steel making process contains a
considerable amount of iron (grain iron). If the agglomerate of
solid particles of such slag is used as it is, since the CaO
composition in the agglomerate of solid particles is lowered by the
amount of the iron content, it is preferable to use slag having
passed through a metal (iron) recovery treatment. The metal (iron)
recovery treatment is generally carried out for recycling the iron
content in slag to the iron-steel making process, and ordinarily
slag is crushed for recovering the metal therein, and a
considerable amount of the iron content is recovered and removed
from slag by means such as a magnetic separation.
[0097] As a concrete, for example, waste concrete may be used which
are made by destroying buildings or from civil engineering
projects.
[0098] These materials are crushed into grain like or grain as
needed and used as the agglomerate of solid particles.
[0099] As mentioned above, in the agglomerate of solid particles to
be the CO.sub.2 absorbing material, it is preferable that the
basicity be high, for example, ane agglomerate of solid particles
where the basicity is less than 1.5 as the water granulated slag,
has a poor solubility of Ca ion, and is low in the reactivity with
CO.sub.2, and therefore it may not be said that the function as the
CO.sub.2 absorbing material is fully exhibited. This is why solid
particles having a low basicity have a small amount of calcium
silicate to be carbonized (e.g., 2CaO.SiO.sub.2 or 3CaO.SiO.sub.2),
or have much glass as the water granulated slag.
[0100] Therefore, when utilizing, as the CO.sub.2 absorbing
material, an agglomerate of solid particles having a low basicity
(ordinarily the basicity is less than 1.5), it is preferable to mix
them with solid particles having a high basicity to be an alkaline
stimulating agent for heightening the solubility of Ca ions from
the solid particles having a low basicity, preferably an
agglomerate of solid particles having a basicity being 1.8 or
higher, adding water thereto (preferably after an air wetting cure
(hydration cure)), and employing the thus obtained mixture as the
CO.sub.2 absorbing material. The solid particles having a high
basicity of 1.8 or higher, act as an alkaline stimulating agent to
the solid particles of having a low basicity under the existence of
the water content, and accelerate the hydration of solid particles
having a low basicity.
[0101] For example, in the case of a solid particle having lower
contents of calcium silicate and CaO, the hydration of calcium
silicate and CaO within the solid particle is accelerated by the
alkaline stimulating agent, and as a result, Ca ions are ready to
be dissolved from the solid particle and, even if a solid particle
is per se less in calcium silicate and CaO, the dissolution of Ca
ions is heightened as a whole. In addition, in the case of a solid
particle having much glass, a silicate network forming the glass by
ane alkaline stimulating agent is broken, and simultaneously the
hydration thereof is accelerated, resulting in increasing the CaO
content enabling carbonation.
[0102] Further, it is useful for heightening the CO.sub.2 absorbing
efficiency to prepare a condition of easily carbonating CaO by
advancing the hydration effected by an air wetting cure (hydration
cure) after the water addition. Namely, since a certain period of
time is needed for the dissolution of alkali, by only mixing only
solid particles of a low basicity and solid particles of a high
basicity and by simply adding water, it is insufficient to
effectively heighten the solubility of Ca ions of the solid
particles having a low basicity. Therefore, desirably, after mixing
the agglomerates of both solid particles, an air wetting cure is
performed for a requisite period of time.
[0103] Such an air wetting cure brings about, as mentioned later,
introduction of cracks into the solid particles or a refining
effect of the solid particles, and also as a result, the CO.sub.2
absorbing ability of the solid particles is increased.
[0104] The air wetting cure may be carried out by a simple method
of, for example, mixing an agglomerate of solid particles having a
high basicity and an agglomerate of solid particles having a low
basicity, kneading the mixture under the existence of an
appropriate amount of water content, and covering the mixture with
a vinyl sheet. However, for preventing carbonation of the solid
particles during curing, it is preferably carried out under an
atmosphere substantially not containing CO.sub.2, otherwise under
an atmosphere substantially not supplied with CO.sub.2 during at
least curing, and accordingly, for example, in a space (atmosphere)
cutting off the atmosphere. CO.sub.2 contained in the atmospheric
air exists at first in such a space, however more CO.sub.2 is not
supplied.
[0105] The time period for the air wetting cure is not especially
limited, however, for obtaining desirable effects by the air
wetting cure, practicing an air wetting cure for more than 12
hours, desirably 24 hours is preferable.
[0106] After practicing the air wetting cure, the mixture may be
pulverized for use as the CO.sub.2 absorbing material. By the
pulverizing treatment, the contacting area with the exhaust gas
containing CO.sub.2 is increased, and the reactivity with CO.sub.2
is heightened.
[0107] Further reference will be made to an effective method for
heightening the CO.sub.2 absorbing ability of the solid
particles.
[0108] The solid particles (for example, waste concrete or slag
generated in the iron-steel making process) to be used as the
CO.sub.2 absorbing material is generally massive or grain, and
since it takes a long time for reacting with CO.sub.2 until an
interior of the solid particles, a CaO source at the interior of
the solid particle trends to be less usefully used for absorption
of CO.sub.2. For solving this problem, it is useful to subject the
massive or grain solid particles to the air wetting cure (hydration
cure) so as to effect hydration expansion and, by this hydration
expansion, cracks are introduced into the solid particle.
Otherwise, breakage occurs from this crack into fine grains and, as
the surface area of the solid particle to be contacted with
CO.sub.2 is increased, the absorbing effect of CO.sub.2 by the CaO
source is effectively improved. Further, it is possible to change a
CaO containing substance in the solid particles to be a hydrated
substance being ready for a carbonating reaction by the air wetting
cure and also, as a result, the absorbing effect of CO.sub.2 by the
CaO source is increased.
[0109] When the agglomerate of solid particles is
hydration-expanded by the air wetting cure, preferably the
agglomerate of solid particles is laid in an atmosphere
substantially not containing CO.sub.2, otherwise in an atmosphere
substantially not supplied with CO.sub.2 during at least curing,
and the air wetting cure is performed under the existence of the
water. For supplying a water content to the agglomerate of solid
particles, there is a method of adding water or warm water to the
agglomerate of solid particles before and/or after laying the
agglomerate of solid particles in the space for the air wetting
cure, or a method of blowing steam to the agglomerate of solid
particles laid in the space for the air wetting cure.
[0110] The reason why the air wetting cure is carried out in an
atmosphere substantially not containing CO.sub.2, otherwise in an
atmosphere substantially not supplied with CO.sub.2 during at least
curing, is because the solid particles do not cause the carbonating
reaction, preferably, for example, in a space (atmosphere) cutting
off the atmosphere. CO.sub.2 contained in the atmospheric air
exists at first in such a space, however more CO.sub.2 is not
supplied.
[0111] When adding warm water to the agglomerate of solid
particles, 60.degree. C. or higher is desirable from the viewpoint
of effective curing.
[0112] The agglomerate of solid particles having passed the air
wetting cure may serve as the CO.sub.2 absorbing material.
[0113] There is no special restriction in the actual means for
contacting the exhaust gas with the agglomerate of solid particles,
however the following may be exemplified as suitable treating
systems in aspects of treating efficiency or ease of handling the
agglomerate of solid particles.
[0114] (1) A system of contacting the exhaust gas with an
agglomerate of solid particles in a fluidized bed using the exhaust
gas as a fluidizing gas.
[0115] (2) Another system of contacting the exhaust gas with an
agglomerate of solid particles in a rotary kiln.
[0116] (3) A further system of forming a layer filled up with an
agglomerate of solid particles, supplying the exhaust gas in the
packed bed, thereby to contact the exhaust gas and the agglomerate
of solid particles.
[0117] FIG. 2 shows one practiced embodiment of the above (1)
system, wherein reference numeral 1 designates a processing
container furnished with a gas dispersing plate 100 at a lower part
and structured thereon with a space A for forming the fluidized
bed, 2 is a device for supplying an agglomerate of solid particles
in the processing container 1, 3 is a conduit for supplying the
exhaust gas containing the CO.sub.2 into the processing container 1
(a wind box 110 below the dispersing plate 100), 4 is a conduit for
issuing the exhaust gas from the processing container 1, and 5 is a
solid particle exhausting pipe for taking out an agglomerate of
solid particles in the processing container 1 from time to
time.
[0118] According to this treating system, the agglomerate of solid
particles such as slag or concrete is supplied from the supply
device 2 into the space A of the processing container 1, while the
exhaust gas supplied from the gas supply conduit 3 into the wind
box 110 is blown out into the space A from the gas dispersion plate
100, and the fluidized bed of the agglomerate of solid particle is
formed. In the fluidized bed, the solid particles and CO.sub.2 in
the exhaust gas are reacted, and CO.sub.2 is fixed as CaCO.sub.3 to
the solid particles. The exhaust gas having finished this reaction
is discharged from the processing container 1 through the gas
discharging conduit 4, and the solid particles within the
processing container 1 is also discharged from the solid particle
discharging pipe 5 in response to the degree (CO.sub.2 absorbing
ability) of absorbing CO.sub.2.
[0119] A plurality of processing containers are installed as shown
with two-doted lines in FIG. 2 and, if the exhaust gas issuing
conduits are connected in series to said plurality of chambers 1,
1a, 1b . . . , in other words, if the exhaust gas is successively
treated through the plurality of processing containers installed in
series in such a manner that the exhaust gas from the processing
container 1 is supplied to the chamber 1a, and the exhaust gas from
the chamber 1a is sent to the chamber 1b, it is possible to
effectively curtail CO.sub.2 in the exhaust gas.
[0120] The form of the fluidized bed for the treating system (1) is
arbitrary and is not limited to that of FIG. 2.
[0121] FIG. 3 shows one practiced embodiment of the above (2)
system, wherein reference numeral 6 designates a rotary kiln, 7 is
a device for supplying the agglomerate of solid particles into the
rotary kiln 6, 8 is a gas supply conduit for supplying the exhaust
gas containing CO.sub.2 into the rotary kiln, 9 is a gas
discharging conduit for issuing the exhaust gas from the rotary
kiln 6, and 10 is a solid particle exhausting pipe for taking out
the agglomerate of solid particles within the rotary kiln.
[0122] According to this treating system, the agglomerate of solid
particles such as slag or concrete is supplied from the supply
device 7 into a treating space of the rotary kiln 6, while the
exhaust gas is supplied from the gas supply conduit 8, and the
agglomerate of solid particles reacts with CO.sub.2 in the exhaust
gas as being mixed in the rotary kiln 6, and CO.sub.2 is fixed as
CaCO.sub.3 to the solid particles. The exhaust gas having finished
this reaction is discharged from the rotary kiln 6 through the gas
discharging conduit 9, and the solid particles having reached an
exit of the rotary kiln 6 are also discharged from the solid
particle discharging pipe 10.
[0123] Also in this system, a plurality of rotary kilns are
installed as shown with two-doted lines in FIG. 3, and if the
exhaust gas issuing conduits are connected in series to said
plurality of rotary kilns 6, 6a, 6b, in other words, if the exhaust
gas is successively treated through the plurality of rotary kilns
installed in series in such a manner that the exhaust gas from the
rotary kiln 6 is supplied to the rotary kiln 6a, and the exhaust
gas from the rotary kiln 6a is sent to the rotary kiln 6b, it is
possible to effectively curtail CO.sub.2 in the exhaust gas.
[0124] The form of the rotary kiln for the treating system (2) is
arbitrary, and is not limited to that of FIG. 3.
[0125] FIG. 4 shows one practiced embodiment of the above (3)
system, wherein reference numeral 11 designates a closed or a half
closed type container for forming a layer filled up by the
agglomerate of solid particles, 12 is a gas supply conduit for
blowing the exhaust gas containing CO.sub.2 into the container 11,
and 13 is a gas discharging conduit for issuing the exhaust gas
from the container 11.
[0126] According to this treating system, the agglomerate of solid
particles is charged into the container 11 to form a layer filled
up thereby, to which the exhaust gas is supplied from the gas
supply conduit 12, and while the exhaust gas flows through the
packed bed, CO.sub.2 in the exhaust gas reacts with the solid
particles, and CO.sub.2 is fixed as CaCO.sub.3 to the solid
particles. The exhaust gas having finished this reaction is
discharged from the container 11 through the gas discharging
conduit 13. In this system, since the agglomerate of solid
particles in the container 11 is not fluidized as the fluidized
bed, ordinarily solid particles are massively combined with one
another by carbonating reaction. Therefore, after having processed
for a certain period of time, the agglomerate of combined solid
particles is taken out from the container 11, and subsequently the
agglomerate of new solid particles is charged into the container
11.
[0127] Also in this system, a plurality of containers are installed
as shown with two-doted lines in FIG. 4, and if the exhaust gas
issuing conduits are connected in series to said plurality of
containers 11, 11a, 11b . . . , in other words, if the exhaust gas
is successively treated through the plurality of containers
installed in series in such a manner that the exhaust gas from the
container 11 is supplied to the container 11a, and the exhaust gas
from the container 11a is sent to the container 11b, it is possible
to effectively curtail CO.sub.2 in the exhaust gas.
[0128] The form of the container for the treating system (3) is
arbitrary, and is not limited to that of FIG. 4.
[0129] In this treating system (3), if the filling rate of the
agglomerate of solid particles in the packed bed is small, the
exhaust gas becomes less to contact with the solid particles to
affect influences with respect to the treating efficiency, and it
is preferable that the filling rate of the agglomerate of solid
particles is 40 to 90 vol. %, desirably 50 to 75 vol. %.
[0130] The CO.sub.2 composition in the exhaust gas contacting with
the agglomerate of solid particles also governs the treating
efficiency, and if it is too low, the treating efficiency is
decreased. For efficiently removing CO.sub.2 in the exhaust gas,
the CO.sub.2 concentration should be more than 5% (preferably 10%
or higher). As the exhaust gases, there are listed exhaust gases
from CaCO.sub.3, a calcination furnace, a hot blast furnace, a
boiler, a coke oven, a sintering furnace, a slab heating furnace or
an annealing furnace.
[0131] In the characteristics of the method of this embodiment,
there is no problem that the exhaust gas of relatively low CO.sub.2
concentration is to be treated by the method of this
embodiment.
[0132] For heightening the treating efficiency, it is preferable
that the exhaust gas to be supplied into the treating space is
pressurized. The gas pressure is not especially limited, however
since the higher the partial pressure of CO.sub.2, the higher the
dissolving speed of CO.sub.2 into the surface adhesive water of
solid particles, if CO.sub.2 is contacted with the agglomerate of
solid particles under the condition that CO.sub.2 is pressurized,
the treating efficiency can be heightened in comparison with
contacting at atmospheric pressure.
[0133] The exhaust gas containing CO.sub.2 to be treated by the
present embodiment includes gases containing CO.sub.2 issued from
various kinds of facilities or equipment, and these exhaust gases
(exhaust gases containing CO.sub.2) are of course not limited. The
exhaust gas containing CO.sub.2 to be treated by the present
embodiment includes, for example, gas generated in the iron-steel
making process and utilized as fuel gas, so-called secondary gas
(for example, gases from a blast furnace, converter or coke oven),
irrespective of which is a combustion exhaust gas or a gas usable
as fuel. Various kinds of exhaust gases generated from an iron
making firm generally include CO.sub.2 of high concentration, and
as mentioned above, since the amount of the final energy
consumption by all the iron and steel firms accounts for about 11%
of the whole of Japan, the method of this embodiment may be said to
be very useful for the treatment of many kinds of exhaust gases
particularly generated from the iron making firms (the iron-steel
making process).
[0134] As the secondary gas caused in the iron-steel making process
such as a blast furnace, converter or coke oven has a high caloric
value, it is used as a fuel gas. On the other hand, CO.sub.2 is
relatively substantially included in these exhaust gases (secondary
gases), and is exhausted into the atmospheric air by and by (after
having been used as fuel), a caloric value as the fuel gas is
lowered by an amount containing CO.sub.2, the amount of using the
fuel gas is correspondingly increased by the amount of lowering the
caloric value, and as a result the amount of generating CO.sub.2 is
increased.
[0135] Accordingly, in the method of this embodiment, it is
possible to make the fuel gas high in calories and cut the amount
of generating CO.sub.2 in total together while decreasing the
amount of the fuel gas used.
[0136] Further reference will be made to the preferable embodiment
of the invention.
[0137] [a1] The method of reducing exhaust carbon dioxide, wherein
at least one part of said agglomerates of solid particles is a slag
generated in an iron-steel making process, and/or concrete.
[0138] [a2] The method of reducing exhaust carbon dioxide, wherein
the solid grain comprising the agglomerates of solid particles is a
slag generated in iron-steel making processes, and/or concrete.
[0139] [b] The method of reducing exhaust carbon dioxide, wherein
the agglomerates of solid particles comprise at least one selected
from the group consisting of concrete, mortar, glass, alumina
cement, CaO containing refractories, and a slag generated in the
iron-steel making process.
[0140] Other embodiments may be enumerated as follows.
[0141] [c] The method of reducing exhaust carbon dioxide as set
forth in any of the above [1] to [14] (the method of [1] to [14]
described in the "Summary of the Invention"), characterized in that
the slag is a slag which has passed a metal recovering
treatment.
[0142] [d] The method of reducing exhaust carbon dioxide as set
forth in any of the above [1] to [14] and [a1] to [c],
characterized in that weight ratio of CaO/SiO.sub.2 of the
agglomerates of solid particles to be contacted with the exhaust
gas containing CO.sub.2 is 1.2 or higher.
[0143] [e] The method of reducing exhaust carbon dioxide as set
forth in any of the above [1] to [14] and [a1] to [d],
characterized in that the exhaust gas containing CO.sub.2 and the
agglomerates of solid particles are contacted within a fluidized
bed, wherein the exhaust gas serves as a gas for fluidizing.
[0144] [f] The method of reducing exhaust carbon dioxide as set
forth in any of the above [1] to [14] and [a1] to [d],
characterized in that the exhaust gas and the agglomerates of solid
particles are contacted within a rotary kiln.
[0145] [g] The method of reducing exhaust carbon dioxide as set
forth in any of the above [1] to [14] and [a1] to [d],
characterized by forming a packed bed which is filled with the
agglomerates of solid particles, and supplying the exhaust gas into
said packed bed, thereby to contact the exhaust gas with the
agglomerates of solid particles.
[0146] [h] The method of reducing exhaust carbon dioxide as set
forth in the above [g], characterized by blowing the exhaust gas
into said packed bed, thereby to contact the exhaust gas with the
agglomerates of solid particles.
[0147] [i] The method of reducing exhaust carbon dioxide as set
forth in the above [h], characterized by blowing said exhaust gas
into the agglomerates of solid particles from one direction,
thereby to contact the exhaust gas with the agglomerates of solid
particles.
[0148] [j] The method of reducing exhaust carbon dioxide as set
forth in the above [g], characterized in that the packing ratio of
the agglomerates of solid particles in the packed layer is 40 to 90
vol. %.
[0149] [k] The method of reducing exhaust carbon dioxide as set
forth in any of the above [1] to [14] and [a1] to [j],
characterized in that the concentration of CO.sub.2 in the exhaust
gas to be contacted with the agglomerates of solid particles is 5%
or more.
[0150] [l] The method of reducing exhaust carbon dioxide as set
forth in any of the above [1] to [14] and [a1] to [k],
characterized in that the agglomerates of solid particles where the
weight ratio of CaO to SiO.sub.2 is less than 1.5 and the
agglomerates of solid particles where the weight ratio of CaO to
SiO.sub.2 is 1.8 or more, are mixed, and contacted with the exhaust
gas containing CO.sub.2 under a condition where the mixture is
added with the water content.
[0151] [m] The method of reducing exhaust carbon dioxide as set
forth in the above [l], characterized in that the agglomerates of
solid grain of the weight ratio of CaO to SiO.sub.2 being less than
1.5 are a water granulated slag from a blast furnace.
[0152] [n] The method of reducing exhaust carbon dioxide as set
forth in the above [l] or [m], characterized in that the
agglomerates of solid particles where the weight ratio of CaO to
SiO.sub.2 is less than 1.5 and the agglomerates of solid particles
where the weight ratio of CaO to SiO.sub.2 is 1.8 or more, are
mixed, and performed with an air wetting curing.
[0153] [o] The method of reducing exhaust carbon dioxide as set
forth in the above [n], characterized by operating a hydration
curing for 12 hours or more.
[0154] [p] The method of reducing exhaust carbon dioxide as set
forth in the above [n] or [o], characterized in that the
agglomerates of solid particles are performed with the air wetting
curing, and then crushed.
[0155] [q] The method of reducing exhaust carbon dioxide as set
forth in any of the above [1] to [14] and [a1] to [q],
characterized in that the agglomerates of solid particles are
performed with the air wetting curing so that the solid particles
are hydration-expanded, thereby to be finely crushed by cracking
and/or breaking, and the agglomerates of solid particles after the
air wetting curing is contacted with the exhaust gas containing
CO.sub.2.
[0156] [r] The method of reducing exhaust carbon dioxide as set
forth in the above [q], characterized by performing the air wetting
curing in an atmosphere substantially not containing CO.sub.2 or an
atmosphere being substantially not supplied with CO.sub.2 during at
least curing.
[0157] [s] The method of reducing exhaust as set forth in the above
[q] or [r], characterized by adding water or warm water to the
agglomerates of solid particles to be performed with the air
wetting curing.
[0158] [t] The method of reducing exhaust carbon dioxide as set
forth in the above [s], characterized in that the temperature of
the warm water to be added to the agglomerates of solid particles
is 60.degree. C. or higher.
[0159] [u] The method of reducing exhaust carbon dioxide as set
forth in the above [q] or [s], characterized by blowing steam into
the agglomerates of solid particles to be performed with air
wetting curing.
[0160] [v] The method of reducing exhaust carbon dioxide as set
forth in any of the above [1] to [14] and [a1] to [u],
characterized in that the exhaust gas containing CO.sub.2 is an
exhaust gas generated in the iron-steel making process.
[0161] [w] The method of reducing exhaust carbon dioxide as set
forth in any of the above [1] to [14] and [a1] to [u],
characterized in that the exhaust gas containing CO.sub.2 is an
exhaust gas to be used as fuel gas.
[0162] [x] The method of reducing exhaust carbon dioxide as set
forth in the above [w], characterized in that the exhaust gas to be
used as the fuel gas is a secondary gas (for example, one or two
kinds of gases from the blast furnace, converter and coke oven)
generated in the iron-steel process.
[0163] Further reference will be made to Examples relating to the
above-mentioned embodiments.
EXAMPLE 1
[0164] A pipe shaped reactor of 2 m length having an inlet and an
outlet for the exhaust gas at both ends was filled with the slag
(grain size: 10 mm or lower, CaO: 35 wt. %, water content: 6%,
packing ratio: 50 vol. %) . The packed bed was supplied with the
exhaust gas (CO.sub.2 concentration: 20%, temperature: 40.degree.
C.) at the gas pressure: 0.3 kgf/cm.sup.2-G for 24 hours, and as a
result of measuring the CO.sub.2 absorbing amount by the slag, the
absorbed CO.sub.2 was about 0.2 at value of CO.sub.2/slag.
[0165] Being based on this CO.sub.2 absorbing amount, when the
CO.sub.2 absorbing amount in a real machine was calculated by
trial, the calculation meant that it was possible to absorb
CO.sub.2 of 15,000 t/year (in terms of C), using 200,000 t/year of
slag.
EXAMPLE 2
[0166] Prepared were the as-slowly cooled dephosphorized slag of 48
wt. % CaO, and the slag where said dephosphorized slag was charged
in a steel-made container, blown with steam under the condition of
cutting off the air, and performed with an air wetting cure
(hydration cure).
[0167] The cured slag and the non-cured slag were passed through a
20 mm screen to produce grain like slags of -20 mm size. These
slags were investigated with respect to the ratio of grain like
slags of -5 mm, using a 5 mm screen.
[0168] The above cured slag and the non-cured slag of -20 mm grain
size were respectively adjusted to be the 6% water content, and
charged 2 kg into the molds (100 mm.times.200 mm), and blown with
carbon dioxide (CO.sub.2 concentration: 20%, temperature:
25.degree. C.) 2 liter/min for 24 hours from the mold bottoms, and
the slags were recovered to measure the CO.sub.2 absorbing (fixing)
amount.
[0169] The results are shown in Table 1. According to the results,
in Examples 2-1, cracks were introduced in the slag grain by the
hydration expansion owing to the air wetting cure, and in
comparison with the non-cured slag, the ratio of fine slag of -5 mm
or smaller increased by 10 wt. %, and as seen from this, cracks
occurred in the slag grains by hydration expansion, so that, when
using the cured slag, the CO.sub.2 absorbing efficiency was more
heightened than Example 2-2, and more CO.sub.2 could be
absorbed.
1TABLE 1 Examples Treating conditions 2-1 Examples Hydration curing
time (hr) 24 0 Carbon dioxide passing time 24 24 Slag amount (wt.
%) of -5 mm before 50 40 supplying carbon dioxide CO.sub.2
absorbing (fixing) amount (wt. %) 14 6
[0170] In relation with the above mentioned first embodiment, a
second embodiment is concerned with a sea-water immersion block, a
method of making the same, a river water immersion block, a method
of making the same, and a method for providing algae planting
places. Reference will be made thereto.
[0171] Immersion Block in Sea-water
[0172] The inventors made experiments and investigations, and as a
result, they found the following facts.
[0173] (1) Grain like slags, rough grain like slags or small
massive slags, in particular such slags moderately containing an
iron content are consolidated with a binder of CaCO.sub.3 or
CaCO.sub.3 and MgCO.sub.3 produced by a carbonating reaction, and
the thus consolidated massive slag is used as sea water-immersion
blocks, thereby displaying excellent effects in the rearing of
marine algae without increasing the pH of the sea water.
[0174] (2) On the other hand, for a sea area which necessitates to
control for a shortage of oxygen in the sea water owing to the
oxidation of iron content or an excessive supply of iron content
into the sea water, the grain-like or the rough grain like slags
having passed the metal removing treatment are consolidated with a
binder of CaCO.sub.3 or CaCO.sub.3 and MgCO.sub.3 produced by a
carbonating reaction. The thus consolidated massive slag is used as
sea water-immersion blocks, thereby displaying excellent effects in
the rearing of marine algae without causing a shortage of oxygen in
the sea water owing to oxidation of iron content or an excessive
supply of iron content into the sea water or increasing the pH of
the sea water.
[0175] (3) For obtaining the massive immersion block in the sea
water as mentioned above, such a production method is useful which
consolidates the above mentioned slags by piling or packing at a
desired composition of at least one slag selected from the group of
the grain like slag, the rough grain like slag and the small
massive slag, otherwise the grain like or rough grain like slag
having passed the metal removing treatment, and by causing a
carbonating reaction in the piled or packed bed under the existence
of carbon dioxide. According to this production method, it is
possible to produce blocks of arbitrary density and size in
response to conditions of sea bottoms or ocean currents to be
applied with blocks.
[0176] The present embodiment has been practiced based on the above
mentioned findings, and is characterized as follows.
[0177] (1) The embodiment is concerned with immersion blocks in the
sea of a main raw material being a slag generated in the iron-steel
making process, consolidating the slag with a binder of CaCO.sub.3
produced by carbonating reaction, and making the slag massive. This
slag is at least one selected from the group of the grain like
slag, the rough grain like slag and the small massive slag. The
present slag is sufficient with grain like or rough grain like slag
having passed a metal removing treatment.
[0178] (2) The embodiment is concerned with immersion blocks in the
sea of a main raw material being a slag generated in the iron-steel
making process, consolidating the slag with a binder of CaCO.sub.3
and MgCO.sub.3 produced by a carbonating reaction, and making the
slag massive. The embodiment includes a case where MgCO.sub.3
exists as a hydrate, hydroxide salt or double salt. This slag is at
least one selected from the group of the grain like slag, the rough
grain like slag and the small massive slag. The present slag is
sufficient with grain like or rough grain like slag having passed a
metal removing treatment.
[0179] (3) The embodiment is concerned with immersion blocks in the
sea of main raw materials being a slag generated in the iron-steel
making process, grain like additives and/or rough grain like
additives, consolidating a mixture of the slag and the additives
with a binder of CaCO.sub.3 produced by a carbonating reaction, and
making the slag massive. This slag is at least one selected from
the group of the grain like slag, the rough grain like slag and the
small massive slag. The present slag is sufficient with grain like
or rough grain like slag having passed a metal removing
treatment.
[0180] (4) The embodiment is concerned with immersion blocks in the
sea of main raw materials being a slag generated in the iron-steel
making process, grain like additives and/or rough grain like
additives, consolidating a mixture of the slag and the additives
with a binder of CaCO.sub.3 and MgCO.sub.3 produced by a
carbonating reaction, and making the slag massive. The embodiment
includes a case where MgCO.sub.3 exists as a hydrate, hydroxide
salt or double salt. This slag is at least one selected from the
group of the grain like slag, the rough grain like slag and the
small massive slag. The present slag is sufficient with grain like
or rough grain like slag having passed the metal removing
treatment.
[0181] (5) A method of making immersion blocks in the sea water is
characterized in that the slag generated in the iron-steel making
process is, as needed, mixed with one kind or more selected from
CaO, Ca(OH).sub.2, MgO and Mg(OH).sub.2, and the slag is piled, or
the packed bed is formed in an arbitrary space, and is subjected to
a carbonating reaction under the existence of carbon dioxide so as
to consolidate the slag for providing blocks of the massive slag.
This slag is at least one selected from the group of the grain like
slag, the rough grain like slag and the small massive slag. The
present slag is sufficient with grain like or rough grain like slag
having passed a metal removing treatment.
[0182] (6) A method of making immersion blocks in the sea water is
characterized in that the slag generated in the iron-steel making
process is mixed with grain like additives and/or rough grain
additives and is, as needed, mixed with one kind or more selected
from CaO, Ca(OH).sub.2, MgO and Mg(OH).sub.2, and the slag is piled
or the packed bed is formed in an arbitrary space, and is subjected
to a carbonating reaction under the existence of carbon dioxide so
as to consolidate the slag for providing blocks of the massive
slag. This slag is at least one selected from the group of the
grain like slag, the rough grain like slag and the small massive
slag. The present slag is sufficient with grain like or rough grain
like slag having passed the metal removing treatment.
[0183] (7) In the embodiments (1) to (6), one part or all of the
slag generated in the iron-steel making process may be replaced
with a CaO containing material (for example, waste concrete).
[0184] The present embodiment is concerned with the immersion
blocks in the seawater of a main raw material being a slag
generated in the iron-steel making process. As the slag generated
in the iron-steel making process, there may be enumerated slags
from blast furnaces such as a slowly cooled slag or a water
granulated slag therefrom. That is to say, slags from the
iron-steel making process such as dephosphorized slag, desulfurized
slag, desiliconized slag, decarburized slag or casting slag
generated in pre-treatments, converter or casting; slags from iron
ore reduction; or slags from electric furnaces. However, no limit
is provided to them. Slag mixtures containing two kinds or more of
slag may be used.
[0185] Of these slags, the compositions of representative ones will
be exemplified as follows.
[0186] (1) Decarburized slag . . . T.Fe: 17.5%, CaO: 46.2%,
SiO.sub.2: 11.7%, Al.sub.2O.sub.3: 1.4%, MgO: 8.3%, MnO: 6.2%, P:
0.76%, S: 0.04%
[0187] (2) Dephosphorized slag . . . T.Fe: 5.8%, CaO: 54.9%,
SiO.sub.2: 18.4%, Al.sub.2O.sub.3: 2.8%, MgO: 2.3%, MnO: 1.9%, P:
2.8%, S: 0.03%
[0188] (3) Desulfurized slag . . . T.Fe: 10.5%, CaO: 50.3%,
SiO.sub.2:10.0%, Al.sub.2O.sub.3: 5.4%, MgO: 1.1%, MnO: 0.4%, P:
0.13%, S: 1.8%
[0189] (4) Desiliconized slag . . . T.Fe: 10.5%, CaO: 13.6%,
SiO.sub.2: 43.7%, Al.sub.2O.sub.3: 3.8%, MgO: 0.4%, MnO: 15.8%, P:
0.10%, S: 0.19%
[0190] (5) Water granulated slag: T.Fe: 0.3%, CaO: 42.0%,
SiO.sub.2: 33.8%, MnO: 0.3%, MgO: 6.7%, Al.sub.2O.sub.3: 14.4%
[0191] Incidentally, among the slags generated in the iron-steel
making process, the dephosphorized slag is high in P content and
the desiliconized slag is high in MnO. Therefore, those are
difficult to be used as raw materials for cement. However, the
invention can make use of them as main raw materials of the sea
water-immersion blocks with no accompanying problem involved
therewith.
[0192] The slags generated in the iron-steel making process as
mentioned above contain relatively much metal (iron content as
grain iron) though more or less (ordinarily, around several wt % to
30 wt %), and metals in slags are pulverized to recover for
recycling the iron content to the iron-steel making process.
Accordingly, including the grain like, rough grain like or small
massive slags, the slags having passed the metal recovering process
are necessarily the grain like, rough grain like or small massive
slags. Ordinarily, grain sizes of the slag having passed the metal
recovering process are at cm-order or smaller (for example, 5 cm or
smaller).
[0193] The present embodiment employs at least one of these grain
like, rough grain like or massive slags for sea water-immersion
blocks.
[0194] The slag to be employed in the embodiment is sufficient with
at least one of the grain like, rough grain like or massive slags,
and it is not a necessary condition to pass the metal recovery
treatment.
[0195] Herein, by the metal recovery treatment is meant a treatment
for yielding metals from slags aiming at recycling metals contained
in slags, and this is different from a treatment for substantially
removing metals in slags as the metal removing treatment.
Therefore, the slag in the metal recovery treatment is not
pulverized finely as in the metal removing treatment, and so the
treated slag still contains much metal. On the other hand, by the
metal removing treatment is meant a treatment which finely
pulverizes the slag in grain like or rough grain like and removes
all metals except inevitably remaining ones.
[0196] When these slags are rendered to be raw materials of sea
water-immersion blocks, the iron containing amount is not required
to be low as in the case where the slag having passed the later
mentioned metal removing treatment is rendered to be a raw material
of block. Rather, it is better that the iron content of a proper
amount (particularly, metallic iron or alloyed iron material such
as grain iron) is contained in slag. This is why the iron content
contained in the slag in a proper amount is dissolved in the sea
water, so that the iron content is supplied as a nutrient salt in
the sea water, and this usefully works for rearing marine algae.
Thus, the iron content in slag is appropriately 3-wt % or more.
[0197] The iron content in slag is adjusted by the following two
methods.
[0198] (a) The metal (such as grain iron) contained per se in slag
is utilized as it is, not recovering parts or all but leaving it to
remain.
[0199] (b) All of the substantial parts of the metal in slag
(excepting the metal, which cannot inevitably be removed) are
removed through the metal removing treatment and are added with
metallic iron or metal containing iron materials as additives.
[0200] Depending on the method (b), the following merits are
brought about.
[0201] (1) In the method (a) which leaves the metal (such as grain
iron) contained per se in slag is utilized as it is, not recovering
one part, it is difficult to correctly adjust the amount of the
metal remaining in slag. Namely, the metal recovery from slag is
carried out by a magnetic separation, and owing to the nature of
the magnetic separation, it is very difficult to recover the metal,
leaving the metal of a certain amount in slag. If possible, a
troublesome control or operation is required for carrying out the
magnetic separation. On the other hand, in the method (b), since
all of the substantial parts of the metal per se contained in slag
are removed and anew added with the metallic iron or the metal
containing iron materials as additives, the iron content in slag
can be arbitrarily controlled.
[0202] (2) For the same reason as above, the method (a) which
leaves the metal (such as grain iron) contained per se in slag, not
recovering parts, cannot select shapes or sizes of the metal in
slag. As later mentioned, what is preferable in general is
so-called grain iron as the iron content contained in the slag
which comprises the sea water-immersion blocks.
[0203] (3) However, for partially recovering the metal by the
magnetic separation, such grain iron does not always remain, but
rather it is recovered and removed, and large sized metal is
probably left. On the other hand, the method (b) can arbitrarily
select shapes and sizes of metallic iron to be added to the slag,
and a desirable iron source such as grain iron can be contained in
the slag.
[0204] Therefore, for obtaining slags containing metallic iron or
metal containing iron materials, it is most preferable to once
remove all substantial parts in slag (except inevitably removable
metals) by a metal removing treatment, and to add the metallic iron
or metal containing iron materials as new additives.
[0205] In general, as later mentioned, the metal removing treatment
is carried out by the magnetic separation after pulverizing slags
into grain or rough grain. Including slags of grain like or rough
grain like states per se, the slag having passed the metal removing
treatment becomes inevitably grain or rough grain. Ordinarily, the
slag passing the metal removing treatment a has grain size of
mm-order or smaller.
[0206] In the above metal removing treatment, metals in slags are
desirably removed as much as possible, except inevitably removable
metals. Normally, the iron content (metal) in slag after the metal
removing treatment is preferably less than 3 wt %. With respect to
the slag having passed the metal removing treatment, such slags are
obtained which have the iron content of a desired amount containing
the metallic iron such as grain iron and/or the metal containing
iron material.
[0207] As the metallic iron or the metal containing iron material
to be added into slag, the following is taken into consideration.
One of them is that, when molding the slag, the metallic iron or
the metal containing iron material of large shapes do not hinder
the molding. The other is to enlarge specific surface areas of such
as the metallic iron contained in slag for heightening dissolution
of the iron content from blocks immersed in the sea water. From the
above viewpoint, preferable are those of small grain size and
uniform scale, and from this, the grain iron is most desirable. As
the grain iron, not only grain iron recovered from slag but also
other grain iron arbitrarily available may be used.
[0208] Depending on circumstances of sea water areas of the
immersion block, there is a possibility of encountering problems of
a shortage of oxygen in the sea water owing to an oxidation of the
iron content in the slag or an excessive supply of iron content in
the sea water. In order to solve the above-mentioned problems, the
slag to be used is subjected to a metal removing treatment and is
used as raw material of a block material without adding metal iron
or metal including iron material.
[0209] The slags generated in the iron-steel making process as
mentioned above contain relatively much metal, though more or less,
and the metals in slags are recovered at considerable degree by the
metal recovering treatment. However since the slag content and the
metal are mixed (entangled), the metal cannot be completely removed
by a pulverizing treatment of such degree as an ordinary metal
recovering process, and so a considerable amount of metal remains
in the slag after the metal recovering process. Therefore, for
sinking of a sea water block obtained from slag having passed only
a metal recovery, problems will arise with respect to a shortage of
oxygen in the sea water owing to the oxidation of iron content in
slag or excessive supply of iron content into the sea water. Thus,
for blocks to be applied to such sea areas, the slags to be raw
material are those which have removed main metal by passing a metal
removing treatment.
[0210] As mentioned above, since the slag content and the metal are
mixed in slag (entangled), it is necessary to remove the metal by
magnetic separation under conditions of using pulverized slags into
grain like or rough grain like. Including slags of grain or rough
grain states per se, the slag having passed the metal removing
treatment becomes inevitably grain or rough grain. Ordinarily, the
slag passing the metal removing treatment has a grain size of
mm-order or smaller (for example, 5 mm or lower).
[0211] Therefore, for the sea water-immersion blocks of the
invention to be applied in the sea area involved with the problems
concerning the shortage of oxygen in the sea water owing to
oxidation of the iron content in slag or the excessive supply of
iron content in the sea water, the raw material is the slag shaped
in grain and/or rough grain having passed the metal recovering
treatment.
[0212] In the metal removing treatment, metals in slags are
desirably removed as much as possible, except inevitably removable
metals. Normally, the iron content (metal) in slag is preferably
less than 3 wt %.
[0213] In the present embodiment, it is found that a main raw
material is at least one slag selected from a group of grain like
slag, rough grain like slag and small massive slag. Otherwise, the
main material is a slag of grain like and/or rough grain like slag,
which has passed the metal removing treatment. This is consolidated
(carbonation solidification) as the binder of CaCO.sub.3 or
CaCO.sub.3 and MgCO.sub.3, and the massive blocks are well-suited
materials as blocks for algae planting places, building rocky
beaches or fish gathering rocky places. At least the above
mentioned slag includes such slags added with metallic iron and/or
metal containing iron material.
[0214] It is an old technique to consolidate grains by reacting CaO
and CO.sub.2, that is, utilizing CaCO.sub.3 produced by a
carbonation reaction. If the grain containing CaO is laid under an
atmosphere of carbon dioxide, CaCO.sub.3 is produced by the
following formula, and a consolidating phenomenon occurs as a
binder of CaCO.sub.3 among grains.
CaO+CO.sub.2.fwdarw.CaCO.sub.3
[0215] Previously, as techniques making use of the carbonation
reaction, there are proposals of a method of making a raw material
with a mixture of water and air-granulated slag in a steel-making
process for making solidified products for buildings (e.g.,
Japanese Laid-Open Patent 58-74559), or a method of making
non-calcined pellets (e.g., Japanese Laid-Open Patents 57-92143,
58-48642, and 58-133334). However these prior art publications aim
only at making hardened products or non-calcined pellets having
desired strength in a short period of time. These publications make
no reference to block materials obtained by consolidating, through
a carbonation reaction, grain like, rough grain like or small
massive slags, otherwise the grain or rough grain like slags
passing a metal recovering treatment, and that the thus obtained
blocks are very useful materials as sea water-immersion blocks for
algae planting places owing to properties thereof.
[0216] With respect to the grain containing MgO, if it is laid
under an atmosphere of carbon dioxide, MgCO.sub.3 is produced by
the carbonation reaction and a consolidating reaction occurs as a
binder of MgCO.sub.3 among grains. MgCO.sub.3 generated by a
carbonation reaction of MgO is variously modified as an anhydrate,
a hydrate (for example, a dihydrate, a trihydrate, a pentahydrate)
hydroxide salt (basic magnesium carbonate), and a trihydrate of
MgCO.sub.3 is produced by the following formula.
MgO+CO.sub.2+3H.sub.2O.fwdarw.MgCO.sub.3.3H.sub.2O
[0217] In general, the slag generated in the iron-steel making
process contains a considerable amount of CaO (ordinarily, 20 to 60
wt. %), and the block materials to be immersed in the sea according
to the present invention are those produced by changing, into
CaCO.sub.3, at least one slag selected from the group of the grain
like slag, the rough grain like slag and the small massive slag,
otherwise CaO or Ca(OH).sub.2 modified from this CaO (including as
needed CaO, Ca(OH).sub.2) contained in grain like slag and/or the
rough grain like slag, and consolidating to make massive the slag
grains (if containing the additives, grain or slag grain) with a
binder of CaCO.sub.3.
[0218] Major parts of slags contain MgO of a certain amount
together with CaO, and the block materials to be immersed in the
sea according to the present embodiment where such slag is the raw
material, changes MgO or Mg(OH).sub.2 modified from this MgO
(including as needed MgO, Mg(OH).sub.2) into MgCO.sub.3 by the
above mentioned carbonation reaction, and consolidating to make
massive the slag grains (if containing the additives, grain or slag
grain) with a binder of MgCO.sub.3 and CaCO.sub.3.
[0219] Incidentally, as mentioned above, MgCO.sub.3 produced by the
carbonation reaction of MgO is variously modified as an anhydrate,
a hydrate or a hydroxide salt, and MgCO.sub.3 contained as the
binder in the sea water-immersion blocks of the invention is
sufficient with any formed MgCO.sub.3. For example, the hydrates of
MgCO.sub.3 are MgCO.sub.3.2H.sub.2O, MgCO.sub.3.3H.sub.2O or
MgCO.sub.3.5H.sub.2O, and hydroxide salt (basic magnesium
carbonate) is MgCO.sub.3.Mg(OH).sub.2.3H.- sub.2O,
4MgCO.sub.3.Mg(OH).sub.2.4H.sub.2O, 4MgCO.sub.3.Mg(OH).sub.2.5H.su-
b.2O, or 4MgCO.sub.3.Mg(OH).sub.2.8H.sub.2O. Further, MgCO.sub.3
combines with other salts to form various double salts, and
MgCO.sub.3 existing as these double salts is sufficient.
[0220] With respect to the slag generated in the iron-steel making
process, parts or all of CaO or MgO contained therein are sometimes
changed into Ca(OH).sub.2 or Mg(OH).sub.2 by water absorption as
time passes or other causes, however this is no problem to the
block to be utilized in the invention, and Ca(OH).sub.2 or
Mg(OH).sub.2 are changed into CaCO.sub.3 or MgCO.sub.3 as the
immersion blocks in the sea.
[0221] The immersion blocks in the sea have the following merits as
blocks for algae planting places, building rocky beaches or fish
gathering rocky places.
[0222] (1) Major parts of CaO (or Ca(OH).sub.2 produced from CaO)
contained in the slag is changed into CaCO.sub.3, and so the pH of
the sea water is prevented from increasing by CaO. On the other
hand, the iron content (in particular, metallic iron or metal
containing iron material) of a proper amount is contained in slag,
and this iron content is dissolved, thereby to supply an iron
content as a nutrient salt which is useful for rearing marine algae
in the sea water.
[0223] (2) At least one slag selected from the group of the grain
like slag, the rough grain like slag and the small massive slag,
otherwise the massive slag obtained by carbonation-solidifying the
grain like slag and/or the rough grain like slag having passed the
metal removing treatment, have porous properties as a whole
(surface and interior), so that the marine algae easily attach to
the surfaces of blocks. In addition, since the interior of the
block is also porous, elements contained in blocks useful for
growing and accelerating of the algae (for example, later mentioned
soluble silica or iron content) are easily dissolved. Therefore,
those can effectively accelerate growing of the marine algae
compared to the case of using massive slags per se for building sea
water-immersion blocks or fish gathering rocky places made of
concrete where the slag is an agglomerate.
[0224] In particular, for effectively accelerating the increase and
living of marine algae on immersion blocks at places of building
algae planting places, the living of young algae should be
accelerated on the block surfaces. In this regard, as the useful
elements dissolving in the water from immersion blocks effectively
work if individuals of the marine algae are near to blocks, they
are very useful to the living of young algae.
[0225] (3) When using massive slags per se as immersion blocks,
because of restraints of cooling methods or conditions of molten
slags, dimensions of slag are limited (ordinarily, about 800 mm at
maximum), and it is difficult to provide large massive blocks of
regular sizes. On the other hand, at least one slag selected from
the group of the grain like slag, the rough grain like slag and the
small massive slag (otherwise the blocks obtained by carbonation
solidifying the grain like slag and the rough grain like slag), can
arbitrarily adjust the size by selecting shapes when
carbonation-solidifying or selecting cut shapes after the
carbonation solidification. It is possible to easily obtain large
massive blocks particularly suited to algae planting places or fish
gathering rocky places.
[0226] (4) It is preferable to use immersion blocks in the sea of
optimum density (specific gravity) in response to conditions of sea
bottom or currents. For example, when sinking blocks of large
density to sea bottoms such as piling of sludge, the blocks are
immersed into the sludge and cannot serve as algae places or fish
gathering places. In this regard, at least one slag selected from
the group of the grain like slag, the rough grain like slag and the
small massive slag, otherwise the blocks obtained carbonation
solidifying the grain like slag and/or the rough grain like slag
having passed the metal removing treatment, can arbitrarily adjust
the density by appropriately adjusting bulk density (compaction
density).
[0227] (5) In the case of blocks for sinking in the sea obtained
from the grain like slag and/or rough grain like slag having passed
the metal removing treatment, since the main metal content is
removed, if the blocks are applied in such sea areas having
problems regarding the shortage of oxygen of the sea water or an
excessive supply of the iron content, there occurs no problem of a
shortage of oxygen in the sea water by oxidation of the metal or
the excessive supply of the iron content by dissolution thereof.
Further, the blocks for sinking in the sea obtained from slag
having removed the metal have relatively many components
attributing to the carbonation solidification of the slag by an
amount of removing the metal, and those are useful for securing
strength.
[0228] The blocks for sinking in the sea of the present embodiment
are produced by closely consolidating slags of small diameter with
binders of CaCO.sub.3 or CaCO.sub.3 and MgCO.sub.3 produced by the
carbonation reaction, and have enough strength. So, when
transferring or sinking in the sea, those are not cracked or
broken, even after having laid in the sea for a long period of a
year.
[0229] For providing suited compositions in response to conditions
of sea areas to be applied, it is possible to contain various kinds
of additives (grain like slag, rough grain like slag or small
massive additives) into the immersion blocks in the sea, together
with at least one slag selected from the group of the grain like
slag, the rough grain like slag and the small massive slag,
otherwise the blocks obtained carbonation solidifying the grain
like slag and the rough grain like slag having passed a metal
removing treatment. As the additives, enumerated are such as grains
or rough grains to be a soluble silica source (soluble silica or
materials containing soluble silica), grain like or rough grain
like to be an iron source (metallic iron, metal containing iron
material, oxidized iron or oxidized iron containing materials), or
CaO of grain like or rough grain like. For CaO contained as the
additive in the immersion blocks in the sea, it is necessary to
leave at least parts of CaO to be significantly added to CaO
contained in the slag or the slag as non-reacted CaO after a
carbonation solidification.
[0230] The soluble silica or the iron source (iron or oxidized
iron) contained in the immersion blocks is dissolved in the sea,
thereby to usefully work to sustain the living of marine algae.
From the viewpoint of the dissolution in the seawater and the
breeding of marine algae, the metallic iron or the metal containing
iron material among the iron sources are particularly preferable.
However, there are some cases wherein the seawater immersion blocks
obtained from the grain like slag and/or rough grain like slag
having passed a metal removing treatment are applied in such sea
areas having problems concerning the shortage of oxygen in the sea
water or excessive supply of the iron content. In this case, the
metallic iron or the metals containing iron material are not
added.
[0231] When phosphorus is a cause of a red tide or sulfur is a
cause of a blue tide are substantially contained in the sea bottom,
CaO contained a bit in the immersion blocks absorbs phosphorus or
sulfur. In the case wherein CaO is substantially contained in the
block material as mentioned above, there is a problem of increasing
the pH of the seawater, however, for absorbing phosphorus or
sulfur, it is sufficient to contain CaO in a small amount to an
extent of remaining after the carbonation solidification.
[0232] As grains or rough grains to be the soluble silica source,
included are the soluble silica and/or the material containing the
soluble silica of the grain or rough grain. As a material
containing the soluble silica, fly ash or clinker ash may be used
which are generated by coal combustion such as in a thermal power
station. The fly ash contains the soluble silica in an amount of 45
to 75 wt. %, while the clinker ash contains 50 to 65 wt. %.
[0233] The water granulated slag from a blast furnace also contains
relatively much soluble silica, and if parts or all of the slag are
rendered to be the water granulated slag, for example, if a slag by
steel making and the water granulated slag are mixed, a similar
effect is brought about to the case of adding the additive to be a
soluble silica source.
[0234] As the grain or the rough grain to be the iron source,
included are the grains or the rough grain as the grain iron, the
metallic iron, or the metal containing iron material, the grain
like or rough grain like oxidized iron and/or the oxidized iron
containing material, and in particular, cheaply available grain or
rough grain are iron containing dusts generated in the iron-steel
making process. The iron containing dust is generally a dust from
iron making, and ordinarily contains oxidized iron of about 75% in
terms of Fe. Mill scales also contains oxidized iron of about 70%
in terms of Fe.
[0235] As mentioned above, when sinking blocks of large specific
gravity to the sea bottom such as piling of sludge, the blocks are
immersed into the sludge and cannot serve as algae places or fish
gathering places. Therefore, with respect to the block material to
be used to the sea bottom of piled sludge, it is preferable that a
slag of relatively small specific gravity is a main raw material,
and specifically, it is useful to use the water granulated slag of
the small specific gravity rather than that of other slag as at
least one part of the main raw material.
[0236] The block material of the present embodiment is relatively
porous, thereby bringing about the above-mentioned effects.
Percentage of voids is not especially limited, however normally
about 10 to 70% is the preferable percentage of voids.
[0237] Explanation will now be provided for a method of making
block materials to be immersed in the sea.
[0238] FIG. 5 is one example showing the production flow of the
inventive method, and FIG. 6 is one example showing the production
procedure according to said flow. The slag generated in the
iron-steel making process is at first subjected to a metal recovery
where a considerable amount of the metal content is removed from
the slag. Ordinarily, in this metal recovering process, the slag is
pulverized into a grain size of cm-order or lower (for example, 5
cm or less) by such as a crusher to be grain, rough grain or small
massive slags, followed by the metal recovery. The slag is
sufficient with a grain size enabling recovery of the metal, and
accordingly, if being relatively rough owing to properties of the
slag, those enabling to recover the metal are pulverized to a
degree enabling to remove the metal.
[0239] In the above mentioned metal recovery, the metal content in
the slag after the recovering treatment may not be as low as a
later mentioned metal removing treatment, and the metal of a proper
amount may be left remaining. This is why the iron content in the
slag in a proper amount is dissolved in the seawater, so that the
iron content is supplied as a nutrient salt in the seawater, and
this is useful for rearing marine algae. Thus, the metal content in
slag is appropriately 3 wt. % or more after the recovering
treatment.
[0240] There are some of slags brought in as stated where the slags
are naturally destroyed to grain sizes enabling to recover the
metal (namely, the naturally destroyed states in grain, rough grain
or small massive grain), and the pulverizing treatment as mentioned
above is not necessary therefor. For example, non-slagged CaO in
the slag after cooling and solidifying reacts with the water
content in air, rainwater or sprinkled cooling water and generates
Ca(OH).sub.2, and by this generation the slag is expanded and
destroyed, otherwise in a slag having a basicity (CaO/SiO.sub.2)
being near to 2, 2CaO.SiO.sub.2(C.sub.2S) is produced , and this
C.sub.2S creates transforming expansion during cooling and the slag
is destroyed or crushed. The slags which are naturally destroyed by
these causes to grain sizes enabling to recover the metal may be
practiced with the metal recovery.
[0241] Ordinarily, the metal recovering treatment is carried out by
a magnetic separation of a magnetic separator (a method of removing
the grain iron content from the slag by magnet), however no
limitation is made thereto. For example, available is a gravity
density method such as an air separation making use of a difference
in specific gravity between the metal content and the slag
content.
[0242] The metal recovering treatment recovers the metal content in
the slag.
[0243] The slag having passed the above mentioned metal recovery is
at least one slag selected from the group of the grain like slag,
rough grain like slag and the small massive slag, and is sent to a
subsequent carbonation solidification or a preparatory treatment.
The raw slag is sufficient with at least one of slags selected from
the group of the grain like slag, rough grain like slag and the
small massive slag, and it is not a necessary condition to pass the
metal recovering procedure.
[0244] Many slags which have passed the metal recovering process,
contain the grain like slags or rough grain like slags more than a
certain ratio, though being more or less. Therefore, even if the
slag contains small massive slag grains of relatively large
diameter, there is scarcely the possibility of causing hindrances
in carbonation-solidifying the slag grains into a state having a
predetermined strength, since grain or rough grain like slags pack
spaces among the small massive slag grains. However, when the slag
is composed of only substantially small massive slag grains, or
when the ratio of the small massive slag grain occurring in the
slag is relatively high, since the contacting areas of the slag
grains are small, there might be a probability of causing
hindrances in carbonation-solidifying the slag grains into a state
having a predetermined strength. Therefore, it is preferable to
adjust the grain size by increasing the ratio of the grain like
slags or rough grain like slags.
[0245] The iron content in slag may be utilized as it is without
recovering parts or all of the metal contained per se in the slag.
However, in order to optionally control, as mentioned above, the
iron content contained in the slag, in order to arbitrarily select
shapes or sizes thereof, and in order to contain a preferable iron
source such as grain iron, it is preferable to add the metallic
iron and/or metal containing iron materials as additives, after
removing all substantial parts in the slag (except inevitably
non-removable metals) by a metal removing treatment.
[0246] The metal removing treatment is generally performed by
pulverizing the slag by a pulverizer until obtaining mm-order or
smaller (for example 5mm or smaller) particles. The slag is
sufficient with such sizes enabling to remove the metal and,
accordingly, depending on the properties of the slags, those
enabling to remove the metal in spite of being a relatively rough
grain may be pulverized to sizes enabling to remove the metal.
Slags being already grain or rough grain by natural pulverization
do not often need a pulverizing treatment. In the metal removing
treatment, except inevitably remaining metal content, the metal is
preferably removed as much as possible. The metal content in slag
is less than 3 wt. % after the removing treatment.
[0247] Ordinarily, the metal recovering treatment is carried out by
a magnetic separation in a magnetic separator (a method of removing
the grain iron content from the slag by a magnet), however no
limitation is made thereto. For example, available is a gravity
separation method such as an air separation making use of the
difference in specific gravity between the metal content and the
slag content.
[0248] To the slag having passed the metal removing treatment, the
metallic iron as grain iron and/or the metal containing iron
materials are added in the appropriate amounts for obtaining slag
having an iron content of a desired amount containing metallic iron
or the metal containing iron material. This slag is sent to the
subsequent carbonation solidification or the preparatory treatment.
As the metallic iron or the metal containing iron material to be
added into the slag, the grain iron is optimum. As the grain iron,
not only grain iron recovered from the slag, but also arbitrary
grain iron from others can be used.
[0249] FIG. 7 is one example of the production flow of producing
the block materials to be immersed in the sea without adding
metallic iron or the metal containing iron material after
performing the metal removing treatment. FIG. 8 is one example
showing the production procedure according to said flow. The slag
generated in the iron-steel making process is at first subjected to
the metal removing treatment for removing the main metal content.
In general, the slag content and the metal in slag are closely
entwined, and for the metal removing treatment, the slag should be
pulverized in grain size or rough grain, and normally the slag is
pulverized by the pulverizer to mm-order or lower (e.g., 5 mm or
less). The slag is sufficient with such sizes enabling the removal
of the metal and, accordingly, depending on properties of slags,
those enabling the removal of the metal in spite of being
relatively rough grain may be pulverized to sizes enabling to
remove the metal.
[0250] In the metal removing treatment, except inevitably remaining
metal content, the metal should be preferably removed as much as
possible, and the metal content in slag is less than 3 wt. % after
the recovering treatment.
[0251] As mentioned above, there are some slags brought in as
stated where the slags are naturally destroyed to grain sizes
enabling the recovery of the metal, and the pulverizing treatment
as mentioned above is not necessary therefor. The causes of the
natural destruction are as mentioned above, and the slags which are
naturally destroyed by these causes to grain sizes enabling the
recovery of the metal may be practiced with the metal recovery.
[0252] Ordinarily, the metal recovering treatment is carried out by
a magnetic separation of the magnetic separator (a method of
removing the grain iron content from the slag by magnet), however
no limitation is made thereto. For example, available is a gravity
separation method such as a wind separation making use of a
difference in specific gravity between the metal content and the
slag content.
[0253] The metal content in the slag is removed by the metal
removing treatment.
[0254] The slag having passed the above mentioned metal removal is
grain like slag and/or rough slag, and is sent to the subsequent
carbonation solidification or the preparatory treatment
thereof.
[0255] To at least one slag selected from the group of the grain
like slag, the rough grain like slag and the small massive slag,
otherwise the grain like slag and/or the rough grain like slag
having passed the metal removing treatment, the additives are added
if necessary. When CaO or MgO necessary for the carbonation
reaction are insufficient in the slag, one kind or more selected
from CaO, Ca(OH).sub.2, MgO and Mg(OH).sub.2 are added if required
and mixed with the slag. As the additives, enumerated are such as
grains or rough grains to be a soluble silica source (soluble
silica or materials containing soluble silica), grains or rough
grains to be an iron source (metallic iron, metal containing iron
material, an oxidized iron or oxidized iron containing materials),
or CaO. The specific examples are as mentioned above.
[0256] Among them, the soluble silica or the iron source (metallic
iron or oxidized iron) is dissolved in the sea, thereby to usefully
work to sustain the living of the marine algae. From the viewpoint
of the dissolution in the sea water and to sustain the living of
the marine algae, the metallic iron or the metal containing iron
material among the iron sources are particularly preferable.
However, in the case of blocks for sinking in the sea obtained from
the grain like slag and/or rough grain like slag having passed the
metal removing treatment, if the blocks are applied in such sea
areas having problems regarding the shortage of oxygen in the sea
water or an excessive supply of the iron content, the metallic iron
or the metal containing iron material are not added.
[0257] Mixture of the slag and the additional raw materials such as
the additives or CaO may depend on arbitrary methods, for example,
a method of mixing the additional raw material and the slag exhaust
from the metal recovering facility or the metal removing facility
in a hopper, a method of adding the additional raw material to the
slag having passed the metal removing treatment to mix in the metal
recovering facility or the metal removing facility, a method of
mixing by a heavy machinery as a shovel, or a method of mixing by a
concrete mixer car (concrete agitator).
[0258] In this stage, the water content in slag may be adjusted as
needed. The adjustment of water content will be referred to in
detail later.
[0259] The slag which has been added with the additives as needed,
mixed and adjusted in the water content is piled for carbonation
solidification or filled up in optional spaces.
[0260] Herein, for piling the slags, it is sufficient to pile in
the open air. However, it is preferable for the blown carbon
dioxide to flow all over the piled mountains, and it is more
preferable to cover the piled mountains with sheets for preventing
the slag from scattering or fading by rainwater.
[0261] For piling or packing with the slag, available are pits
encircling three corners with partitioning walls, frames or
containers encircling four corners with the partitioning walls.
When piling or packing with the slag within the pit, it is
preferable to cover the piled or filled-up mountains with the
sheets similarly to the open-air freighting. Further, when using a
frame or container, it is desirable to cover the slag packed bed
with the sheet or provide a cover body. FIGS. 6 and 8 show states
where the packed bed A is formed within the frame.
[0262] The piling amount or the filling amount of the slag are not
limited, and said amounts of several tons or several hundred tons
are sufficient, or said amount corresponding to one piece of the
block material or several pieces are enough. Thus the amount is
optional. Although the piling or filling amount is much, if the
piled mountain or the packed bed after the carbonation
solidification are pulverized by heavy machinery, massive block
materials can be cut out, and such cut-out massive blocks have
merits of irregularity fractures for catching marine algae. From
the viewpoint of productivity or functions as blocks for algae
planting places or fish gathering rocky places, it is preferable
that the slag piling or packing amounts are much to a certain
degree.
[0263] The bulk density (compaction density) of the slag pile or
layer is preferably adjusted in response to a density of block to
be produced. Namely, the immersion block in the sea should be
adjusted with respect to the density in response to conditions of
the sea bottom. For example, in the case where the sea bottom is
muddy or sludgy, blocks of relatively low density should be used so
that the blocks are not immersed into the mud or sludge. On the
other hand, in the case where the sea bottom is a reef, etc.,
blocks of relatively high density should be used so that the blocks
are not carried away. Since the adherence of marine algae, the
living degree thereof or dissolution of useful components from the
interior of blocks are varied by the porosity (vacancy) of the
block materials, it is often preferable to adjust the porosity of
the blocks in response to conditions of the sea areas where the
blocks are used.
[0264] The density of blocks to be produced by the method of the
present embodiment depends on the bulk density (compaction density)
of the piled mountain or packed bed, and so, it is possible to
adjust the tightening degree of the piled mountain or packed bed,
and by adjusting the bulk density, the density of block can be
easily adjusted.
[0265] The tightening degree of the slag piled mountain or packed
bed is optional, however ordinarily, the bulk specific gravity/true
specific gravity ranges from 0.3 to 0.9, that is, the tightening is
carried out to a degree that the vacancy within the piled mountain
or packed bed is 70 to 10%.
[0266] The tightening may depend on a method of tightening the
upper part of the piled mountain or packed bed or a method of
giving vibration to tighten the piled mountain or packed bed. By
adjusting the tightening degree, the density of the piled mountain
or packed bed is adjusted. When producing the blocks of low
density, the tightening is not performed, and the carbonation
solidification is practiced as piled or filled up.
[0267] As actually tightening method, when tightening the piled
mountain or packed bed within the above mentioned pit or molding
frame, weighing lines for showing a target volume are marked on the
interior of the pit, molding frame or container, and the slag whose
weight is known is laid therein, and the tightening is continued
until the upper face of the piled mountain or packed bed comes to
the weighing line.
[0268] After completing the adjustment of the bulk specific gravity
of the piled mountain or packed bed of slag, the carbonation
reaction is caused in the piled mountain or packed bed under the
existence of carbon dioxide for carbonation-solidifying the slag.
Specifically, the carbon dioxide or the carbon dioxide containing
gas is blown into the piled mountain or packed bed of slag,
otherwise the piled mountain or packed bed is laid under an
atmosphere of carbon dioxide or a carbon dioxide containing gas for
practicing the carbonation solidification of slag.
[0269] The above blowing manner is not especially limited, however
it is most effective to equip a gas blowing instrument at the
bottom of the piled mountain or packed bed and blow the gas through
this instrument. Actually, gas supplying pipes or hoses are
disposed at an appropriate pitch (e.g., 30 to 300 mm.times.40 to
400 mm) in the bottom of the mountain or layer (if using the pits,
molding frames or containers, in beds thereof) for blowing the
carbon dioxide or the carbon dioxide containing gas.
[0270] Further, as the manner for laying the mountain or layer in
the atmosphere of the carbon dioxide or the carbon dioxide
containing gas, the mountain or layer are laid in air-tight spaces
(including the container), into which the carbon dioxide or the
carbon dioxide containing gas is supplied by an arbitrary
embodiment.
[0271] As the carbon dioxide containing gas to be employed, the
suited examples are as follows. That is to say, an exhaust gas
(normally, CO.sub.2: around 25%) from a limestone baking plant of
an integrated iron making work or an exhaust gas form a reheating
furnace(normally, CO.sub.2: around 6.5%) can be used. However no
limitation is made thereto. If the concentration of carbon dioxide
in the carbon dioxide containing gas is too low, a problem occurs
that the treating efficiency is decreased, however no other problem
appears. Thus, the concentration of carbon dioxide is not limited,
however for efficient treating, it is preferably 3% or higher.
[0272] The gas blowing amount of the carbon dioxide or the carbon
dioxide containing gas is not limited either and, as an ordinary
standard, it is good to use a gas blowing amount of about 0.004 to
0.5 m.sup.3/min.multidot.t. In addition, there is no limitation
especially required for the gas blowing time (carbonation treating
time) and, as a standard, it is desirable to blow the gas until the
blowing amount of carbon dioxide (CO.sub.2) reaches 3% or more of
the weight of the slag, that is, until carbon dioxide (CO.sub.2) of
15 m.sup.3 or more per 1 ton of a material in terms of the gas
amount is supplied.
[0273] The carbon dioxide or the carbon dioxide containing gas to
be blown into the piled mountain or packed bed of slag is
sufficient at room temperature and, if the gas exceeds room
temperature, this is better for reactivity An upper limit of the
gas temperature is a temperature for decomposing CaCO.sub.3 into
CaO and CO.sub.2 or MgCO.sub.3 into MgO and CO.sub.2, and when
using gas at a high temperature, gas at a temperature of not
bringing about such decompositions should be used. An optimum
temperature for actual operation is necessarily determined by
taking conditions of the water content or other conditions into
consideration.
[0274] For carbonation-solidifying the slag by utilizing the
reaction of CaO, MgO and carbon dioxide, a water content is
necessary, and the optimum water content is varied according to the
grains of slags, however it is suitable to have about a 3 to 10%
water content rate in slag immediately before starting the
carbonation treatment. This is because the carbonation reaction is
accelerated by dissolving CaO, MgO and carbon dioxide in the water.
Therefor, it is preferable to adjust the water content in slag to
be an optimum value so as to cause the carbonation reaction under
the existence of carbon dioxide. If the water content in slag is
too low, desirably water is added to the slag in the mixing courses
of FIGS. 5 and 7 for adjusting the water content for heightening
the amount of water contained in slag. If the carbon dioxide or the
carbon dioxide containing gas is once blown into the water to
saturate H.sub.2O, followed by blowing it into the piled mountain
or packed bed, the slag is prevented from being dried to accelerate
the carbonation reaction. Further, it is sufficient to adjust the
water content in mixture to be a value at which a compression
strength of a massive substance is at a maximum after the
carbonation treatment. This value of the water content is obtained
as follows.
[0275] (a) A raw slag of more than 3 standard is prepared, where a
water of an optional amount of more than a water absorption rate of
the raw slag grain is added to 100 wt parts of the raw slag. The
above mentioned water absorption rate is that of a fine aggregate
or coarse aggregate specified by JIS A1109 or A 1110.
[0276] (b) Respective raw slag is charged in the molding frame so
that the porosity under the drying condition is kept to be constant
and homogeneous, and the charged layers are formed.
[0277] (c) The charged layer is blown with carbon dioxide gas
humidified at 10 to 40.degree. C. at a determined amount for
practicing carbonation curing for a fixed time so as to solidify
the raw slag.
[0278] (d) The compression strength of the solidified slag is
measured for obtaining a maximum value thereof. The value of the
water content corresponding to the maximum value is the optimum
water content.
[0279] By supplying the carbon dioxide or the carbon dioxide
containing gas into the piled mountain or the charged layer of the
slag, CaCO.sub.3 or MgCO.sub.3 is produced by the reaction between
CaO (or Ca(OH).sub.2) or MgO (or Mg(OH).sub.2) and the carbon
dioxide CaCO.sub.3 or CaCO.sub.3 and MgCO.sub.3 are rendered to be
binders for solidifying the slag grain (if the additive is mixed,
the slag grain and additive grain).
[0280] After completion of the carbonation solidification, the
piled mountain or the charged layer are broken into required sizes
by heavy machinery, and cut out into massive block materials to be
immersed in the sea. Ordinarily, the blocks are cut out into sizes
of 80 to 1500 mm. By this pulverization when cutting out, the
blocks have fractures of irregularities for easily catching marine
algae.
[0281] In the method of the present embodiment, by a sufficient
small volume of charged layer, it can be utilized as the block
material as it is, without cutting out.
[0282] The production method of this embodiment has the following
merits.
[0283] (1) Since the carbonation solidification is practiced under
the conditions of piling the slag in a mountain or a charging
layer, the density of the immersion block in the sea can be easily
adjusted by adjusting the tightening degree of the piled mountain
or the charged layer for adjusting the bulk specific gravity. As
mentioned above, the blocks should be adjusted in the density or
the porosity in response to conditions of the sea bottom or
current, and as the production method, it is a big merit that the
adjustment can be arbitrarily and easily carried out. A
conventionally known technique is to carbonation-solidify
granulates, which is however difficult to adjust the density of
non-treated materials in wide ranges.
[0284] (2) The method of this embodiment carries out the
carbonation solidification under the condition of piling or
charging the slag in a mountain or a layer, breaks the
carbonation-solidified mountain or layer for cutting out the
massive blocks into desired sizes or utilizes the charged-layer as
blocks as they are. So, by appropriately selecting sizes of the
cut-out blocks or the charged layer, the blocks of optional sizes
(for example, 80 to 1500 mm) can be obtained, and large massive
blocks especially suited to algae planting places or fish gathering
rocky places can be easily obtained. In the prior art of
carbonation-solidifying granulated pellets, sizes of obtained
massive products are 30 to 50 mm at the most, besides inevitably
producing massive ones of a small size. Thus, as the production
method of the sea-immersion blocks, it is a big advantage that
large massive blocks can be obtained.
[0285] (3) After the carbonation solidification, the piled mountain
or the charged layer are broken by heavy machinery, and cut out
into massive block materials, so that the blocks have surfaces
(fractures) of irregularities for easily catching marine algae.
[0286] The block materials can exhibit excellent characteristic
when using them for algae planting places, building beaches, or
fish gathering rocky places, and of course they can be used for
other purposes, for example, as blocks for sea bottom mound,
improving or purifying qualities of the sea bottom. Also when the
blocks are used for such purposes, the excellent effects as
mentioned above are exhibited for living marine algae.
EXAMPLE 3
[0287] A converter slag powder (containing small massive slags
produced by the metal recovery, iron content: 12 wt. %) of a
maximum diameter about 30 mm, and a grain size of 5 mm or smaller
and being about 70 wt. %, was piled 1.5 m in a pit of 4 m
width.times.6 m depth, and moderately tightened. Then the pit was
closed and blown with carbon dioxide 50 Nm.sup.3/hr for 3 days so
as to solidify the slag. The carbonation-solidified slag was broken
and divided by heavy machinery to produce massive block materials
of about 1.0 to 1.5 m for algae planting places.
[0288] As a comparative example, mortar was poured into the molding
frame of 1.5 m.times.1.5 m.times.1.5 m, and the solidified concrete
block was divided into two by a breaker (rock drill) to produce
blocks having fractured faces for an algae planting place.
[0289] A sea bottom, which was 4 m deep and near a natural algae
planting place, was selected as a place for building a testing
algae planting place. 15 pieces of the block materials of the above
example and 20 pieces of blocks of the comparative example were
immersed in a scope of diameter being about 10 m. The blocks of the
comparative example were immersed turning the fractured faces
upward. A period of the seasons for sinking blocks was selected
just before spending spores from the natural marine algae planting
place in order that sedimentary substances did not cover the block
surfaces before adhered spores thereto.
[0290] As a result of investigating the places of sinking blocks
after about one year, it was confirmed that marine algae adhered to
all the blocks and lived. The living amount of algae was surveyed
by an investigation of a crop estimate by unit acreage sampling,
and it was confirmed that the humid weight of the blocks of the
comparative example was 956 g/m.sup.2, while the humid weight of
the blocks of the example was 1121 g/m.sup.2, and that the blocks
of the invention were better in adhering rate and for sustaining
the living properties of algae.
EXAMPLE 4
[0291] A converter slag grain like (having passed the metal
recovery, iron content: 2 wt. %) of grain size being 3 mm or
smaller, was piled 1.5 m in a pit of 4 m width.times.6 m depth, and
moderately tightened. Then the pit was closed and blown with carbon
dioxide 50 Nm.sup.3/hr for 3 days so as to solidify the slag. The
carbonation-solidified slag was broken and divided by heavy
machinery to produce the massive block materials of about 1.0 to
1.5 m for algae planting places.
[0292] As a comparative example, mortar was poured into the molding
frame of 1.5 m.times.1.5 m.times.1.5 m, and the solidified concrete
block was divided into two by a breaker (rock drill) to produce
blocks having fractured faces for the algae planting place.
[0293] A sea bottom of 4 m deep near a natural algae planting place
was selected as a place for building a testing algae planting
place. 15 pieces of the block materials of the above example and 20
pieces of blocks of the comparative example were immersed in a
scope of diameter being about 10 m. The blocks of the comparative
example were immersed turning the fractured faces upward. A period
of the seasons for sinking blocks was selected just before spending
spores from the natural marine algae planting place in order that
sedimentary substances did not cover the block surfaces before
spores adhered thereto.
[0294] As a result of investigating the places of sinking after
about one year, it was confirmed that marine algae adhered to all
the blocks and lived. The living amount of algae was surveyed by an
investigation of a crop estimate by unit acreage sampling, and it
was confirmed that the humid weight of the blocks of the
comparative example was 579 g/m.sup.2, while the humid weight of
the blocks of the example was 695 g/m.sup.2, and that the blocks of
the invention were better in adhering rate and sustaining the
living properties of algae.
[0295] According to the above mentioned present embodiments,
neither an increase of the pH in the sea water or a shortage in
oxygen are encountered, and when using them for algae planting
places, building beaches, or fish gathering rocky places, the block
materials can exhibit an excellent performance also for sustaining
the living of marine algae, and in addition, it is possible to
offer the block materials for sinking in the sea which are
adjustable in size and density.
[0296] Further, according to the sea water immersion block of the
invention using raw slag having passed a metal recovering
treatment, in addition to the above mentioned effects, in the sea
areas necessary to suppress the shortage of oxygen in sea water
owing to the oxidation of iron content in slag or the excessive
supply of iron content into the sea water, it is possible to
effectively suppress the shortage of oxygen in the sea water owing
to the oxidation of iron content in slag or the excessive supply of
iron content into the sea water.
[0297] In particular, in the production method of the present
embodiments, as the carbonation solidification is carried out under
the conditions of piling or packing the slags, it is possible to
produce sea water immersion blocks of optional density and sizes
easily and at a low cost by adjusting the degree of tightening of
the piled mountain or the charged layer, or appropriately selecting
sizes of the carbonation-solidified blocks to be cut out.
[0298] There are some slags which have a property to be floured by
a transforming expansion of .gamma.-dicalcium silicate generated
when cooling, or expansion caused by hydration of free CaO.
Conventionally, such floured slag has not been used other than
being partially utilized as raw materials for cements, and major
parts were wasted. However in the present embodiments, floured slag
can be utilized as a raw material. Further, with respect to slags
(for example, dephosphorized slag or desilicated slag) having
difficulties in usefully using them as cement raw materials owing
to restraints in compositions, the inventive method can use them as
the raw material. Thus, this is a very profitable invention also in
a regard of usefully using slags generated in the iron-steel making
process.
[0299] River Water Immersion Block and Production Method
Thereof
[0300] The inventors made experiments and investigations, and as a
result, they found the following facts.
[0301] (1) Grain like slags, rough grain like slags or small
massive slags, in particular such slags moderately containing iron
content are consolidated with a binder of CaCO.sub.3 or CaCO.sub.3
and MgCO.sub.3 produced by a carbonation reaction, and the thus
consolidated massive slag is used as river immersion blocks. It was
found that such blocks exhibit, when used as sinking blocks,
excellent effects in forming spaces for living fishes or the
rearing of water living plants as algae without increasing the pH
of the river water, or to above all display particularly excellent
effects in moving of other water living creatures than fishes or
rearing of water living plants, when sinking or laying blocks to
artificially structural parts or artificial river beds such as fish
ways to be equipped to dams or barrages of rivers.
[0302] (2) On the other hand, for a river-flowing area which
necessitates controlling the shortage of oxygen in the river water
owing to oxidation of iron content or excessive supply of iron
content into the river water, the grain like or rough grain like
slags having passed the metal removing treatment are consolidated
with a binder of CaCO.sub.3 or CaCO.sub.3 and MgCO.sub.3 produced
by carbonation reaction, and the thus consolidated massive slag is
used as river immersion blocks, thereby displaying excellent
effects in the rearing of algae without causing a shortage of
oxygen in the river water owing to the oxidation of iron content or
excessive supply of iron content into the river water or increasing
the pH of the river water.
[0303] (3) For obtaining the massive immersion blocks in the river
water as mentioned above, such a production method is useful which
consolidates the above mentioned slags by piling or packing at a
desired density the grain like slag, the rough grain like slag or
the small massive slag, otherwise the grain like or rough grain
like slag having passed a metal removing treatment, and by causing
the carbonation reaction in the piled mountain or packed bed under
the existence of carbon dioxide. According to this production
method, it is possible to produce blocks of arbitrary density and
size in response to conditions of river beds or water-flowing to be
applied with blocks, and to produce blocks of arbitrary density and
sizes in response to purposes for river beds or fish ways at low
cost.
[0304] The present embodiment is characterized as follows.
[0305] (1) The embodiment is concerned with immersion blocks in the
rivers of a main raw material being a slag produced in the
iron-steel making process, and is characterized by a consolidating
the slag with a binder of CaCO.sub.3 produced by carbonation
reaction, and making the slag massive. This slag is at least one
selected from the group of the grain like slag, the rough grain
like slag and the small massive slag. The present slag is
sufficient with grain like or rough grain like slag having passed a
metal removing treatment.
[0306] (2) The embodiment is concerned with immersion blocks in the
rivers of a main raw material being a slag generated in the
iron-steel making process, and is characterized by consolidating
the slag with a binder of CaCO.sub.3 and MgCO.sub.3 produced by a
carbonation reaction, and making the slag massive. The embodiment
includes a case where MgCO.sub.3 exists as a hydrate, hydroxide
salt or double salt. This slag is at least one selected from the
group of the grain like slag, the rough grain like slag and the
small massive slag. The present slag is sufficient with grain like
or rough grain like slag having passed a metal removing
treatment.
[0307] (3) The embodiment is concerned with immersion blocks in the
rivers of main raw materials being a slag generated in the
iron-steel making process, grain like additives and/or rough grain
additives, and is characterized by consolidating a mixture of the
slag and the additives with a binder of CaCO.sub.3 produced by a
carbonation reaction, and making the slag massive. This slag is at
least one selected from the group of the grain like slag, the rough
grain like slag and the small massive slag. The present slag is
sufficient with grain like or rough grain like slag having passed a
metal removing treatment.
[0308] (4) The embodiment is concerned with immersion blocks in the
rivers of main raw materials being a slag generated in the
iron-steel making process, grain like additives and/or rough grain
additives, is characterized by consolidating a mixture of the slag
and the additives with a binder of CaCO.sub.3 and MgCO.sub.3
produced by a carbonation reaction, and making the slag massive.
The embodiment includes a case where MgCO.sub.3 exists as a
hydrate, hydroxide salt or double salt. This slag is at least one
selected from the group of the grain like slag, the rough grain
like slag and the small massive slag. The present slag is
sufficient with grain like or rough grain like slag having passed a
metal removing treatment.
[0309] (5) A method of making immersion blocks in the river water
is characterized in that the slag generated in the iron-steel
making process is, as needed, mixed with one kind or more selected
from CaO, Ca(OH).sub.2, MgO and Mg(OH).sub.2, and the slag is
piled, or the packed bed is formed in an arbitrary space, and is
caused with the carbonation reaction under the existence of carbon
dioxide so as to consolidate the slag for providing blocks of the
massive slag. This slag is at least one selected from the group of
the grain like slag, the rough grain like slag and the small
massive slag. The present slag is sufficient with grain like or
rough grain like slag having passed a metal removing treatment.
[0310] (6) A method of making immersion blocks in the river water
is characterized in that the slag generated in the iron-steel
making process is mixed with grain like additives and/or rough
grain additives and is, as needed, mixed with one kind or more
selected from CaO, Ca(OH).sub.2, MgO and Mg(OH).sub.2, and the slag
is piled or the packed bed is formed in an arbitrary space, and is
caused with the carbonation reaction under the existence of carbon
dioxide so as to consolidate the slag for providing blocks of the
massive slag. This slag is at least one selected from the group of
the grain like slag, the rough grain like slag and the small
massive slag. The present slag is sufficient with grain like or
rough grain like slag having passed a metal removing treatment.
[0311] The present embodiment is concerned with the immersion
blocks in the river water of a main raw material being a slag
generated in the iron-steel making process. As the slag generated
in the iron-steel making process, there may be enumerated slags
from blast furnaces such as a slowly cooled slag or a water
granulated slag therefrom; slags from the iron-steel making process
such as dephosphorized slag, desulfurized slag, desiliconized slag,
decarburized slag or casting slag generated in pre-treatments, a
converter or casting; slags from iron ore reduction; or slags from
electric furnaces. However, no limit is provided to them. Slags
mixed with two kinds or more of slags may be used.
[0312] The slags generated in the iron-steel making process as
mentioned above contain relatively much metal (iron content as
grain iron) though more or less (ordinarily, around several wt. %
to 30 wt. %), and metals in slags are pulverized to recover for
recycling the iron content to the iron-steel making process.
Accordingly, including the grain like, rough grain like or small
massive slags, the slags having passed a metal recovering process
are necessarily the grain like, rough grain like or small massive
slags. Ordinarily, grain sizes of the slag having passed the metal
recovering process are at cm-order or less (for example, 5 cm or
less).
[0313] The present embodiment employs at least one of these grain
like, rough grain like or massive slags for rivers-immersion
blocks.
[0314] The slag to be employed in the invention is sufficient with
at least one of the grain like, rough grain like or massive slags,
and it is not a necessary condition to pass a metal recovery
treatment.
[0315] When these slags are rendered to be raw materials of the
river immersion blocks, the iron containing amount is not required
to be low as the case where a slag having passed a metal removing
treatment is rendered to be a raw material of a block. Rather, it
is better that the iron content of a proper amount (particularly,
metallic iron or alloyed iron material such as grain iron) is
contained in slag. This is why the iron content contained in the
slag in a proper amount is dissolved in river water, so that the
iron content is supplied as a nutrient salt in river water, and
this usefully works for rearing marine algae. Thus, the iron
content in slag is appropriately 3 wt % or more.
[0316] Depending on circumstances of river areas to be immersed
with blocks, in cases of problems concerning the shortage of oxygen
in the river water owing to the oxidation of iron content in slag
or the excessive supply of iron content into the river water, the
slag to be used is subjected to a metal removing treatment and is
used as a raw material of a block material without adding metal
iron or the metal including iron material.
[0317] The slags generated in the iron-steel making process as
mentioned above contain relatively much metal though more or less,
and the metals in slags are recovered at considerable degree by the
metal recovering treatment. However since the slag content and the
metal are mixed as being entwined, the metal cannot be completely
removed by a pulverizing treatment of such degree as an ordinary
metal recovering process, and so a considerable amount of metal
remains in the slag after the metal recovering process. Therefore,
if sinking in the river blocks obtained from the slag having passed
only a metal recovery, problems will arise concerning the shortage
of oxygen in the river water owing to the oxidation of iron content
in slag or the excessive supply of iron content into the river
water. Thus, for blocks to be applied to such river areas, the
slags to be raw material are those which have removed main metal by
passing a metal removing treatment.
[0318] Since the slag content and the metal are mixed in slag as
being entwined, it is necessary to remove the metal (by a magnetic
separation) under conditions of having pulverized slags into grain
or rough grain. Including slags of grain or rough grain states per
se, the slag having passed a metal removing treatment becomes
inevitably grain or rough grain. Ordinarily, a slag passing the
metal removing treatment has a grain size of mm-order or less (for
example, 5 mm or lower).
[0319] Therefore, for the river immersion blocks of the invention
to be applied in the river areas involved with the problems
concerning the shortage of oxygen in the river water owing to the
oxidation of iron content in slag or the excessive supply of iron
content into the river water, the raw material is the slag shaped
in grain and/or rough grain having passed a metal recovering
treatment.
[0320] In the metal removing treatment, metals in slags are
desirably removed as much as possible, except inevitably removable
metals. Normally, the iron content (metal) in slag is preferably
less than 3 wt. %.
[0321] In the present embodiment, it was found that the main raw
material is at least one slag selected from a group of grain like
slag, rough grain like slag and small massive slag, or the slag of
grain and/or rough grain having passed a metal removing treatment,
and this is consolidated (carbonation solidification) as a binder
of CaCO.sub.3 or CaCO.sub.3 and MgCO.sub.3, and the massive blocks
are very suited materials as blocks for sinking to river beds,
above all as artificially structural parts such as fish ways or
artificial river beds.
[0322] In general, the slag generated in the iron-steel making
process contains a considerable amount of CaO (ordinarily, 20 to 60
wt. %), and the block materials to be immersed in rivers according
to the present invention are those produced by changing, into
CaCO.sub.3, at least one slag selected from the group of the grain
like slag, the rough grain like slag and the small massive slag,
otherwise CaO or Ca(OH).sub.2 modified from this CaO (including as
needed CaO, Ca(OH).sub.2) contained in grain like slag and/or the
rough grain like slag, and consolidating to make massive the slag
grains (if containing the additives, grain or slag grain) with the
binder of CaCO.sub.3.
[0323] Major parts of slags contain a certain amount of MgO
together with CaO, and the block materials to be immersed in rivers
according to the present embodiment where such slag is the raw
material, changes MgO or Mg(OH).sub.2 modified from this MgO
(including as needed MgO, Mg(OH).sub.2) into MgCO.sub.3 by the
above mentioned carbonation reaction, and consolidating to make
massive the slag grains (if containing the additives, grain or slag
grain) with a binder of MgCO.sub.3 and CaCO.sub.3.
[0324] With respect to the slag generated in the iron-steel making
process, parts or all of CaO or MgO contained therein are sometimes
changed into Ca(OH).sub.2 or Mg (OH).sub.2 by water absorption as
time passes or other causes, however this is no problem for the
block to be utilized in the invention, and Ca(OH).sub.2 or
Mg(OH).sub.2 are changed into CaCO.sub.3 or MgCO.sub.3 as immersion
blocks in rivers.
[0325] The river immersion blocks of the present embodiment are
used as river beds or fish ways. The embodiment of installing
blocks in the water is arbitrary as not only merely sinking but
also fixing them to structural parts.
[0326] The river immersion block materials of the present
embodiment are particularly suited as immersion blocks or laid to
the artificially structural parts or artificial river beds as
blocks for fish ways, and the blocks for the fish way are laid or
fixedly laid to the bottom of the fish way. Other than the fish
way, the blocks may be fixedly laid to optional structural parts
such as the upper face of an artificially structural part where the
water flows (for example, moderately oblique face of the
artificially structural part composing part or all of the head-neck
of a barrage) or a fixedly structured artificial river bed (for
example, river beds constructed by block tightening or
rockwork).
[0327] The embodiment (sizes or shapes) for using the river
immersion blocks is optional, and the sizes may be selected in
response to usage from orders of 1000 mm or larger to orders of
several ten mm. When fixedly laying the blocks to the fish ways,
other artificially structural parts or artificial river beds, in
order that an construction is easily carried out, and as cases may
be, the blocks are fixedly laid only with rockworks, it is
desirable to use the blocks in a block, panel, tile or similar
shape (fixedly formed material). Also in the fish ways, it is
sufficient to use the blocks in an embodiment of simply sinking the
massive blocks of a non-fixed form on the bottom thereof.
[0328] FIGS. 9(a) to (c) show structural examples when the blocks
of the invention are immersed or laid on the artificially
structural part or the artificial river bed of such as fish ways,
in which (a) is an example where the block materials 40a in block
or panel shape are fixedly laid on the fish way of oblique road
system. For fixing the blocks 40a, mortar may be used as needed. In
this example, the blocks of the bottom have fractures 40 (cracked
or ruptured faces) The fractures 40 are cracked or ruptured faces
formed when the blocks provided by the carbonation solidification
are cracked or ruptured, and as those are more irregular than
as-carbonation solidified faces, they are effective for water
living creatures to move. FIG. 9(b) is an example of sinking the
massive blocks 40b non-fixedly on the bottoms (respective steps) of
the stepwise fish way. FIG. 9(c) is an example sinking the massive
blocks 40c of block or panel shape fixedly on the artificially
structural parts or the artificial river bed other than the fish
way. As the artificially structural part other than the fish way
applicable with such structure, for example, the moderately oblique
face composing the head-neck of such as barrages may be listed
up.
[0329] The river immersion block have merits as follows as block
materials to be immersed or laid on the river bed.
[0330] (1) Major parts of CaO (or Ca(OH).sub.2 produced from CaO)
is changed into CaCO.sub.3, and so it is possible to prevent algae
from delaying of adhering or living by an increase of pH of the
river water or around the block materials. In general, the pH of
natural blocks (limestone) is around 9.3 and the pH of concrete is
around 12 to 12.5, and the river immersion block of the invention
can be at a pH 10 or lower as a natural block by a neutralizing
reaction at production.
[0331] (2) The massive slag obtained by carbonation-solidifying the
grain like slag and/or the rough grain like slag have porous
properties as a whole (surface and interior), so that such as algae
are easily attach the surfaces of blocks. Besides, since the
interior of block is also porous, elements contained in blocks
useful to growing and accelerating of the algae are easily
dissolved, and the growth of algae is good.
[0332] (3) When using massive slags per se as immersion blocks,
because of restraints of cooling methods or conditions of molten
slags, the dimensions of slag are limited (ordinarily, about 800 mm
at maximum), and it is difficult to provide large massive blocks of
regular sizes. On the other hand, the size of blocks obtained by
carbonation solidifying the slag and/or the rough grain like slag,
can be arbitrarily adjusted by selecting shapes when
carbonation-solidifying or selecting cut shapes after the
carbonation solidification, and it is possible to easily obtain
blocks of arbitrary sizes such as middle massive blocks or small
massive blocks (broken blocks).
[0333] (4) It is preferable to use immersion blocks in rivers of
optimum density.(specific gravity) in response to conditions of the
river bottom or the water flowing speed. In this regard, the
density of blocks obtained by carbonation solidifying the grain
like slag and/or the rough grain like slag having passed a metal
removing treatment, can be arbitrarily adjusted by appropriately
adjusting the bulk density (compaction density).
[0334] (5) In the case of blocks for sinking in the rivers obtained
from the grain like slag and/or rough grain like slag having passed
the metal removing treatment, since the main metal content is
removed, if the blocks are applied in such river areas having
problems concerning the shortage in oxygen of the river water or
excessive supply of the iron content, there occurs no problem of
the shortage in oxygen of the river water by oxidation of the metal
or the excessive supply of the iron content by dissolution thereof.
Further, the blocks for sinking in the rivers obtained from slag
having the metal removed have relatively much components
attributing to the carbonation solidification of the slag by an
amount of the metal removal, and those are useful for securing
strength.
[0335] (6) The blocks of the invention are ordinarily cut out from
the consolidated and piled mountain or charged layer, so that the
block have rocky rugged forms, and when those are immersed or laid
on the river bed, they are easy to make large spaces between blocks
or the river bed and the blocks in comparison with natural round
blocks or similar natural blocks seen at rivers, and so useful
living and resting spaces for water living creatures are easily
formed.
[0336] Further, as mentioned above, the river immersion block of
the invention are very suited above all as artificially structural
parts such as fish ways or the artificial river beds (hereinafter,
an explanation will be made concerning a block for a fish way) in
applications to the rivers, and in such applications, the blocks
have the following merits.
[0337] (7) Surfaces of massive blocks obtained by
carbonation-solidifying the grain like slag and/or rough grain like
slag are porous, and when sinking or laying them to the bottoms of
the fish ways, water living creatures (for example, crusts or water
living insects) which move by catching with their claws the
riverbed (surface projections as block or water living plants) can
easily move. In particular, the blocks of the invention have porous
and rugged surfaces, and also the pH as that of a natural block,
and are ready for dissolving useful components, so that water
living plants are easily adhere and live on the block surfaces, so
that water living creatures more easily move in the fish way.
[0338] (8) When using a stone for a fish way, it is sufficient to
merely sink the massive blocks within the fish way, however
preferably, the blocks molded in a block or panel are fixedly laid
on the bottom of the fish way. In this regard, since the blocks
provided by carbonation-solidifying the grain or rough grain like
slag can be arbitrarily formed at production, block or panel shapes
are easily formed, and if employing such blocks, the construction
is easy to fixedly and exactly lay the blocks on the bottom of the
fish way.
[0339] (9) In comparison with a conventional foamed concrete, the
construction may be carried out at low cost, the pH is lower than
that of the concrete, and it is desirable for water living
creatures moving along the bottom of the fish way.
[0340] As the river immersion block of the invention is
consolidated as the binder of CaCO.sub.3 or CaCO.sub.3 and
MgCO.sub.3, it has sufficient strength, so that even if a shock is
affected while transferring or when sinking to lay a block, cracks
or destruction do not occur for a long period of year.
[0341] For providing suited compositions in response to places to
be applied, it is possible to contain various kinds of additives
(grain, rough grain or small massive additives) together with the
grain like slag and/or the rough grain like slag. As the additives,
for example, enumerated are such as grains or rough grains to be a
soluble silica source (soluble silica or soluble silica containing
materials), grains or rough grains to be an oxidized iron source
(oxidized iron or oxidized iron containing materials).
[0342] The soluble silica or the iron source (iron or oxidized
iron) contained in the immersion blocks in the rivers is dissolved
in the water, thereby to usefully work to sustain the living of
algae.
[0343] As grains or rough grains to be the soluble silica source,
present are the soluble silica and/or the material containing the
soluble silica of the grain or rough grain. As the material
containing the soluble silica, fly ash or clinker ash may be used
which are generated by coal combustion in such as a thermal power
station. The fly ash contains soluble silica in an amount of 45 to
75 wt. %, while the clinker ash contains 50 to 65 wt. %.
[0344] The water granulated slag from a blast furnace also contains
relatively much soluble silica, and if parts or all of the slag are
rendered to be the water granulated slag, for example, if a slag
from steel making and the water granulated slag are mixed, a
similar effect is brought about to the case of adding the additive
to be the soluble silica source.
[0345] As the grain or the rough grain to be the oxidized iron
source, present are the grain like or rough grain like oxidized
iron and/or the oxidized iron containing material, and in
particular, cheaply available grain or rough grain are iron
containing dusts generated in an iron-steel making process. The
iron containing dust is generally a dust from iron making, and
ordinarily contains oxidized iron of around 75% in terms of Fe.
Mill scales also contain oxidized iron of around 70% in terms of
Fe.
[0346] When obtaining blocks of relatively low specific gravity, it
is useful to use a water granulated slag of small specific gravity
as at least one part of the main raw material.
[0347] The river immersion block material of the present embodiment
is relatively porous, thereby bringing about the above mentioned
effects (2). The percentage of voids is not especially limited,
however normally, around 10 to 70% is a preferable percentage of
voids.
[0348] Explanation will be made to a method of making block
materials to be immersed in rivers.
[0349] FIG. 10 is one example showing the production flow of the
inventive method, and FIG. 11 is one example showing the production
procedure. The slag generated in the iron-steel making process is
at first subjected to metal recovery to remove the main metal
(grain iron). Ordinarily, since the slag content in slag and the
metal are closely entangled, a metal recovering treatment should be
carried out on the grain or rough grain like slag, and therefore,
the slag is pulverized by such as a pulverizer to be mm-order or
lower (for example, 5 mm or less), followed by a metal removing
treatment. The slag is sufficient with grain sizes enabling the
metal removing treatment, and accordingly, if being relatively
rough owing to properties of the slag, those enabling recovery of
the metal are pulverized to a degree enabling to remove the
metal.
[0350] There are some slags brought in as stated where the slags
are naturally destroyed to grain sizes enabling recovery of the
metal, and the pulverizing treatment as mentioned above is not
necessary therefor.
[0351] Ordinarily, the metal removing treatment is carried out by a
magnetic separation of the magnetic separator (a method of removing
the grain iron content from the slag by a magnet), however no
limitation is made thereto. For example, available is a gravity
density method such as an air separation making use of a difference
in specific gravity between the metal content and the slag
content.
[0352] The metal content in the slag is removed by a metal removing
treatment.
[0353] The grain like slag and/or the rough grain like slag having
passed a metal removing treatment are added with the additives if
required, and CaO or MgO necessary for carbonation reaction are
short in the slag, one kind or more selected from CaO,
Ca(OH).sub.2, MgO and Mg(OH).sub.2 are added as required and mixed
with the slag. As the additives, for example, added are such as
grains or rough grains to be a soluble silica source (soluble
silica or soluble silica containing materials), grains or rough
grains to be oxidized iron source (oxidized iron or oxidized iron
containing materials) and CaO. Specific examples thereof are as
mentioned above.
[0354] Mixture of the slag and the additive raw materials such as
the additives or CaO may depend on arbitrary methods, for example,
a method of mixing the addition raw material and the slag exhausted
from a metal removing facility in a hopper, a method of adding the
addition raw material to the slag having passed a metal removing
treatment to mix in the metal removing facility, a method of mixing
by a heavy machinery as a shovel, or a method of mixing by a
concrete mixer car (concrete agitator).
[0355] The slag, which has been added with the additives as needed
and mixed, is piled for carbonation solidification or filled up in
optional spaces.
[0356] Herein, for piling, an open-air freighting is sufficient,
and it is preferable to cover the piled mountains with sheets such
that the blown carbon dioxide flows allover the piled mountains,
and for preventing the slag from scattering or fading by
rainwater.
[0357] For piling or packing the slag, available are pits
encircling three corners with partitioning walls, molding frames or
containers encircling four corners with the partitioning walls.
When piling or packing the slag within the pit, it is preferable to
cover the piled or filled-up mountains with the sheets similarly to
the open-air freighting. Further, when using the molding frame or
container, it is desirable to cover the slag packed bed with the
sheet or provide a cover body. FIG. 11 shows a state where the
packed bed A is formed within the frame.
[0358] The piling amount or the packing amount of the slag are not
limited, and said amounts of several tons or several hundred tons
are sufficient, or said amount corresponding to one piece of the
block material or several pieces are enough. Thus the amount is
optional. Although the piling or filling amount is much, if the
piled mountain or the packed bed after the carbonation
solidification are pulverized by the heavy machinery, massive block
materials can be cut out, and such cut-out massive blocks have
merits of irregular fractures for catching algae. From the
viewpoint of productivity and function as river immersion blocks,
it is preferable that the slag piling or packing amounts are much
to a certain degree. Specifically, scales of 10 tons or more are
desirable.
[0359] The bulk density (compaction density) of the slag pile or
layer is preferably adjusted in response to a density of block to
be produced. Namely, the immersion block in rivers should be
adjusted with respect to the density in response to conditions of
the river bottom or the water flowing. Since the adherence of
algae, the living degree thereof or dissolution of useful
components from the interior of blocks are varied by the porosity
(vacancy) of the block materials, it is often preferable to adjust
the porosity of the blocks in response to conditions of the rivers
where the blocks are used.
[0360] The density of block to be produced by the method of the
present embodiment depends on the bulk density (compaction density)
of the piled mountain or packed bed, and so, it is possible to
adjust the tightening degree of the piled mountain or packed bed,
and by adjusting the bulk density, the density of block can be
easily adjusted.
[0361] The tightening degree of the slag piled mountain or packed
bed is optional, however ordinarily, the bulk specific gravity/true
specific gravity ranges from 0.3 to 0.9, that is, the tightening is
carried out to a degree that the vacancy within the piled mountain
or packed bed is 70 to 10%.
[0362] The tightening may depend on a method of tightening the
upper part of the piled mountain or packed bed or a method of
providing vibration to tighten the piled mountain or packed bed. By
adjusting the tightening degree, the density of the piled mountain
or packed bed is adjusted. When producing blocks of low density,
the tightening is not performed, and the carbonation solidification
is practiced as piled or filled up.
[0363] As an actual tightening method, when tightening the piled
mountain or packed bed within the above mentioned pit or molding
frame, weighing lines for showing a target volume are marked on the
interior of the pit, a molding frame or container, and the slag
whose weight is known is laid therein, and the tightening is
continued until the upper face of the piled mountain or packed bed
comes to the weighing line.
[0364] After completing the adjustment of the bulk specific gravity
of the piled mountain or packed bed of slag, the carbonation
reaction occurs in the piled mountain or packed bed under the
existence of carbon dioxide for carbonation-solidifying the slag.
Specifically, carbon dioxide or a carbon dioxide containing gas is
blown into the piled mountain or packed bed of slag, otherwise the
piled mountain or packed bed is laid under an atmosphere of carbon
dioxide or a carbon dioxide containing gas for carrying out the
carbonation solidification of slag.
[0365] The above blowing manner is not especially limited, however
it is most effective to equip a gas blowing instrument at the
bottom of the piled mountain or packed bed and blow the gas through
this instrument. Actually, gas supplying pipes or hoses are
disposed at an appropriate pitch (e.g., 300 mm to 400 mm) in the
bottom of the mountain or layer (if using the pits, molding frames
or containers, in beds thereof) for blowing the carbon dioxide or
the carbon dioxide containing gas.
[0366] Further, as the manner for laying the mountain or layer in
the atmosphere of the carbon dioxide or the carbon dioxide
containing gas, the mountain or layer are laid in air-tight spaces
(including the container), into which the carbon dioxide or the
carbon dioxide containing gas is supplied by an arbitrary
embodiment.
[0367] As the carbon dioxide containing gas to be employed, suited
are, for example, an exhaust gas from a limestone baking plant
(normally, CO.sub.2: around 25%) or an exhaust gas from reheating
furnace (normally, CO.sub.2: around 6.5%) of an integrated steel
making works. However no limitation is made thereto. If the
concentration of carbon dioxide in the carbon dioxide containing
gas is too low, a problem occurs that the treating efficiency is
decreased, however no other problem appears. Thus, the
concentration of carbon dioxide is not limited, however for
efficiently treating, it is preferably 3% or higher.
[0368] The gas blowing amount of the carbon dioxide or the carbon
dioxide containing gas is not limited, either, and as an ordinary
standard, it is good to use a gas blowing amount of around 0.004 to
0.5 m.sup.3/min.multidot.t. In addition, there is no limitation
especially required for the gas blowing time (carbonation treating
time), and as a standard, it is desirable to blow the gas until the
blowing amount of carbon dioxide (CO.sub.2) reaches 3% or more of
the weight of the slag, that is, until carbon dioxide (CO.sub.2) of
15 m.sup.3 or more per 1 ton of a material in terms of the gas
amount is supplied.
[0369] The carbon dioxide or the carbon dioxide containing gas to
be blown into the piled mountain or packed bed of slag is
sufficient at room temperature, and if the gas exceeds room
temperature, this is better for reactivity. An upper limit of the
gas temperature is a temperature for decomposing CaCO.sub.3 into
CaO and CO.sub.2 or MgCO.sub.3 into MgO and CO.sub.2, and when
using gas at high temperature, gas at a temperature of not bringing
about such decompositions should be used.
[0370] For carbonation-solidifying the slag by utilizing the
reaction of CaO, MgO and carbon dioxide, a water content is
necessary, and it is desirable to have around a 3 to 10% water
content ratio in the slag immediately before starting the
carbonation treatment. This is because the carbonation reaction is
accelerated by dissolving CaO, MgO and carbon dioxide in the water.
Therefore, if the water content in slag for composing the piled
mountain or charged layer is too low, the water may be added to the
slag in the mixing course of FIG. 6 for adjusting the water content
for heightening the amount of water contained in slag. If the
carbon dioxide or the carbon dioxide containing gas is once blown
into the water to saturate H.sub.2O, followed by blowing it into
the piled mountain or packed bed, the slag is prevented from being
dried to accelerate the carbonation reaction.
[0371] Further, it is sufficient to adjust the water content in
mixture to be a value at which a compression strength of a massive
substance is at a maximum after the carbonation treatment. This
value of the water content is obtained as follows.
[0372] (a) A raw slag of more than 3 standard is prepared, where
water of an optional amount of more than a water absorption rate of
the raw slag grain is added to 100 wt parts of the raw slag. The
above mentioned water absorption rate is that of a fine aggregate
or a coarse aggregate specified by JIS A1109 or A 1110.
[0373] (b) Respective raw slags are charged in the molding frames
so that the porosity at drying is kept to be constant and
homogenous, and the charged layers are formed.
[0374] (c) The charged layer is blown with carbon dioxide gas
humidified at 10 to 40.degree. C. at a determined amount for
practicing carbonation curing for a fixed time so as to solidify
the raw slag.
[0375] (d) The compression strength of the solidified slag is
measured for obtaining a maximum value thereof. The value of the
water content corresponding to the maximum value is the optimum
water content.
[0376] By supplying the carbon dioxide or the carbon dioxide
containing gas into the piled mountain or the charged layer of the
slag, CaCO.sub.3 or MgCO.sub.3 is produced by the reaction between
CaO (or Ca(OH).sub.2) or MgO (or Mg(OH).sub.2) and the carbon
dioxide. CaCO.sub.3 or CaCO.sub.3 and MgCO.sub.3 are rendered to be
binders for solidifying the slag grain (if the additive is mixed,
the slag grain and additive grain).
[0377] After completion of the carbonation solidification, the
piled mountain or the charged layer are broken into required sizes
by heavy machinery, and cut out into massive block materials to be
immersed in the sea. Ordinarily, the blocks are cut out into sizes
of 80 to 1500 mm. By this pulverization when cutting out, the
blocks have fractures of irregularities for easily catching such as
algae.
[0378] In the method of the present embodiment, if the volume of
charged layer is sufficiently small, it needs no cutting out. It
can be utilized as the block material as it is divided into two
parts. For example, this case may be applied to production of the
block or panel shaped blocks, and if dividing into two parts by
pulverizing or breaking the carbonation-solidified block blocks,
two pieces of block like or panel like blocks having fractures on
the surfaces may be produced.
[0379] The production method of the present invention has the
following merits.
[0380] (1) Since the carbonation solidification is practiced under
the conditions of piling the slag in a mountain or a charging
layer, the density of the immersion block in rivers can be easily
adjusted by adjusting the tightening degree of the piled mountain
or the charged layer for adjusting the bulk specific gravity. As
mentioned above, the blocks should be adjusted in the density or
the porosity in response to conditions of the river bottom or water
flowing, and as the production method of the blocks it is a big
merit that the adjustment can be arbitrarily and easily carried
out. A conventionally known technique is to carbonation-solidify
granulates, which is however difficult to adjust the density of
non-treated materials in wide ranges.
[0381] (2) The method of the present invention carries out the
carbonation solidification under the condition of piling or
charging the slag in a mountain or a layer, breaks the
carbonation-solidified mountain or layer for cutting out the
massive blocks into desired sizes or utilizes the charged layer as
blocks as they are, or divides into massive blocks. So, by
appropriately selecting sizes of the cut-out blocks or the charged
layer, the blocks of optional sizes (for example, 80 to 1500 mm)
can be obtained, and large massive blocks can be easily obtained.
In the prior art of carbonation-solidifying granulated pellets,
sizes of obtained massive products are 30 to 50 mm at the most,
besides inevitably producing massive ones of a small size. Thus, as
the production method of river immersion blocks, it is a big
advantage that large massive blocks can be obtained.
[0382] (3) When fixedly laying blocks to artificially structural
parts or artificial river beds of fish ways, the blocks to be
employed are desirably shaped in a block or a panel, and in the
inventive method, by appropriately selecting sizes or shapes of the
charged layer, such shaped blocks can be easily produced.
[0383] (4) After the carbonation solidification, the piled mountain
or the charged layer of the slag are broken by heavy machinery, and
cut out into massive block materials, so that the blocks, which
have surfaces (fractures) of irregularities for easily catching
algae, can be obtained. Further, with respect to the block or panel
shaped blocks of the above (3), if dividing into two parts by
pulverizing or breaking the carbonation-solidified blocks, two
pieces of a block like or a panel like block having fractures on
the surfaces may be produced.
EXAMPLE 5
[0384] A grain like converter slag of grain size being 3 mm or
smaller, was piled 1.5 m in a pit of 4 m width.times.6 m depth, and
moderately tightened, then the pit was closed and blown with carbon
dioxide 50 Nm.sup.3/hr for 3 days so as to solidify the slag. The
carbonation-solidified slag was broken by heavy machinery to
produce the massive block materials having a size of about 30 to
250 mm with enough strength as river immersion blocks.
EXAMPLE 6
[0385] The raw material was dephosphorized slag grain like of a
diameter of 6 mm or less being 100 wt. %, and blocks for fish ways
were produced by the following two methods.
[0386] (1) The grain like slag was charged in porous molding frames
of 50 cm.times.50 cm.times.15 cm, and tightened, and then 60 pieces
of frames were set within the pit such that spaces were created
between the frames. The pit was closed and blown with carbon
dioxide of 70 Nm.sup.3/hr for 5 days for solidifying the slag.
After that, the molding frames were taken off, and the block shaped
blocks for fish ways were obtained.
[0387] (2) The grain like slag was charged in porous molding frames
of 100 cm.times.100 cm.times.50 cm. For charging, at intermediate
positions of 100 cm width of the molding frames, polyethylene made
partitions opening at the central parts were interposed (100
cm.times.100 cm.times.2 mm, and opening: 85 cm.times.85 cm). The
grain like slab was charged, and the wholes were tightened. 18
pieces of molding frames were set within the pit such that spaces
were created between the frames. The pit was closed and blown with
carbon dioxide of 70 Nm.sup.3/hr for 5 days for solidifying the
slag. After that, the molding frames were taken off, and the
obtained block shaped blocks were broken into two pieces at the
central parts interposing the partitions, having fractures (broken
faces) on the upper surfaces.
[0388] The block shaped blocks for fish ways produced by the above
(1) and (2) were laid as embodied in FIG. 9A on the bottom of the
fish way constructed with concrete. Incidentally, the blocks (2)
for the fish way were laid such that the fractures composed the
bottom of the fish way. Thereby, differently from smooth bottom
parts as the concrete (concrete block or concrete construction),
the obtained fish way had the porous and rugged rough bottom for
shells easily moving.
[0389] As the inventive block of the invention is almost equal pH
as the natural block by neutralizing reaction at production, there
is not such a phenomenon that the concrete-made fish way heightens
pH in the surface by elements dissolved at starting the use after
construction, and algae are delayed in adhering to. As the bottom
of the fish way composed of the inventive blocks has the porous and
rugged rough face, it was confirmed that algae adhered to the
bottom and lived in a relatively short period.
[0390] As mentioned above, according to the above mentioned present
embodiments, neither a shortage in oxygen in the river water or an
increase of pH are encountered, and when sinking or laying as
blocks for river beds, the block materials can exhibit excellent
performance in forming living spaces for fishes or rearing of water
living plants such as algae, and in addition, those display special
functions in the moving of other creatures than fishes or rearing
of water living plants when sinking or laying them on artificially
structural parts or artificial beds provided at dams or barrages.
Also it is possible to offer the block materials for sinking in the
rivers which are adjustable in size and density.
[0391] In particular, in the production method of the present
invention, since the carbonation solidification is carried out
under the conditions of piling or packing the slags, it is possible
to produce a river immersion block of optional density and size
easily and at a low cost by adjusting the degree of tightening of
the piled mountain or the charged layer, or appropriately selecting
sizes of the carbonation-solidified blocks to be cut out.
Especially, for the repairing of river beds, an enormous amount of
blocks are required, however according to the present invention,
blocks can be supplied at low cost, in comparison with cases of
using natural blocks or concrete materials. Thus, the cost of
construction can be curtailed.
[0392] There are some slags which have a property to be floured by
a transforming expansion of .gamma.-dicalcium silicate generated
when cooling, or expansion caused by hydration of free CaO.
Conventionally, such floured slag has been difficult to use as
materials, however in the present embodiments, a floured slag can
be utilized as a raw material. Further, this is a very profitable
invention also in a regard of usefully using slags generated in the
iron-steel making process.
[0393] Creating Method of Algae Places
[0394] The inventors noticed an increasing power or an increasing
action of marine algae in existing algae planting places, and got
an idea of making use of existing algae planting places per se in
adhering and living of seeds and saplings of marine algae to bases.
That is, the inventors had the idea of temporarily laying materials
to be bases for creating algae places so as to cause seeds and
saplings to naturally adhere and live on the surfaces of materials
for utilizing these materials as bases for creating algae planting
places. As a result of having made experiments and studies based on
this idea, they found that if materials of blocks were laid in
existing algae planting places, marine algae adhered and lived on
the surfaces of materials in a relatively short period of day.
Further, if materials with algae living were moved as seeding
materials to places of creating algae planting places, and at the
same time new materials (marine algae not adhering) were placed
around their circumferences, marine algae of seeding materials
increased on the circumferential materials, and formed units of a
community of algae comprising the algae planting places.
[0395] With respect to the materials to be bases for creating the
algae planting places including the above seeding materials,
suitable properties of materials were investigated, and it was
found that if a material had a weight of a degree not to be brought
up by the sea current, however, enabling to stay on the sea bottom,
the properties were of no problem, and preferable were such
materials of surface properties for easily catching spores or seeds
of marine algae, namely, surfaces having ruggedness or projections.
Above all, very suited as materials were artificially made blocks
where slag generated in the iron-steel making process was made
massive through a special technique, exhibiting excellent effects
also in sustaining the living of marine algae.
[0396] The present embodiment has the following
characteristics.
[0397] A method of creating or improving algae planting places,
characterized by temporarily sinking materials comprising weighty
substances on existing algae planting places, adhering and rearing
marine algae on the surfaces of said materials, then recovering the
materials for creating algae planting places or moving as seeding
materials to places for increasing marine algae, and disposing
other materials around said seeding materials for increasing marine
algae of said seeding material on said other materials.
[0398] As the above mentioned materials, it is preferable to employ
artificially made blocks as follows.
[0399] (a) An artificially made block of a main raw material being
a slag generated in an iron-steel making process, where the slag is
consolidated with a binder of CaCO.sub.3 produced by a carbonation
reaction, and made massive. This slag is at least one selected from
the group consisting of grain like slag, rough grain like slag and
small massive slag. The slag is sufficient with grain like slag or
rough grain like slag having passed a metal removing treatment.
[0400] (b) An artificially made block of a main raw material being
a slag generated in an iron-steel making process, where the slag is
consolidated with a binder of CaCO.sub.3 and MgCO.sub.3 produced by
a carbonation reaction, and made massive. The embodiment includes a
case where MgCO.sub.3 exists as a hydrate, hydroxide salt or double
salt. The slag is at least one selected from the group consisting
of grain like slag, rough grain like slag and small massive slag.
The slag is sufficient with grain like or rough grain like slag
having passed a metal removing treatment.
[0401] (c) An artificially made block of a main raw material being
a slag generated in an iron-steel making process, grain like
additives and/or rough grain additives, where a mixture of the slag
and the additives is consolidated with a binder of CaCO.sub.3
produced by a carbonation reaction, and made massive. This slag is
at least one selected from the group consisting of grain like slag,
the rough grain like slag and small massive slag. The slag is
sufficient with grain like or rough grain like slag having passed a
metal removing treatment.
[0402] (d) An artificially made block of a main raw material being
a slag generated in an iron-steel making process, grain like
additives and/or rough grain additives, where a mixture of the slag
and the additives is consolidated with a binder of CaCO.sub.3 and
MgCO.sub.3 produced by a carbonation reaction, and made massive.
The embodiment includes a case where MgCO.sub.3 exists as a
hydrate, hydroxide salt or double salt. This slag is at least one
selected from the group consisting of grain like slag, rough grain
like slag and small massive slag. The slag is sufficient with grain
like or rough grain like slag having passed the metal removing
treatment.
[0403] Other than creating algae planting places in such lands
where algae do not grow or are decayed, these embodied methods may
be applied for improving (rearing the algae) places where algae
planting places are decaying.
[0404] A detailed explanation will be made to a method of creating
algae planting places (or improving method).
[0405] In the present embodiment, at first, materials to be seeding
materials are temporarily immersed in the existing algae places (in
particular preferably, natural algae places). As an existing algae
place, first of all, a natural algae place exists in circumstances
where marine algae are easy to increase (circumstances of light,
water quality or ocean current governing growth of algae) in
comparison with places where algae do not naturally live, and
besides the algae planting place is a site where seeds or spores
(zoospore) released from algae exist in the highest density.
Accordingly, an existing algae place is the site most suited for
adhering and rearing algae on the surfaces of the materials.
[0406] The materials to be immersed to the algae planting places
are of no problem regarding material properties or shapes, if the
materials have a weight of a degree not to be brought up by the
ocean current, however, enabling to stay on the sea bottom. As the
materials, if, for example, natural blocks, artificial blocks
(including massive slag or concrete blocks), metallic materials
(e.g., steel materials or cast products), plastic materials, or
their compound materials, exceed a specific gravity being 1, no
problem is involved with material properties. Further, shapes are
not especially limited, and appropriate forms may be selected as
massive, lengthy, block, plate, or one material in a basket or a
net of plural massive substances.
[0407] Materials having ruggedness or indentations on the surfaces
are easy for adhering spores seeds of marine algae, and rooting
germs. When the material is a block, it is most desirable to form
the rugged surface with a broken face when pulverizing. As the
broken face of the block material is formed with countless
ruggedness, the adhering of spores seeds of marine algae and the
living of germs are good.
[0408] Especially preferable are artificially made blocks which
will be referred to in detail.
[0409] In regard to materials other than one material which is made
by packing plural massive substances in a basket or a net, when
temporarily sinking said materials, it is convenient to wrap them
in nets for pulling up or attach pulling-up instruments (such as
wire rope) for making later recovery easy.
[0410] As to a period of season for temporarily sinking materials
to the algae planting places, it is desirable to select a period
when marine algae in the algae planting places actively release
spores or seeds. On the surfaces of the immersion blocks, algae
usually adhere and grow in several months to around one year, and
some of those fast growing develop to mature making spores or
seeds, or grow up nearly it. As mentioned above, existing algae
plating places (especially natural algae places) have the most
actively increasing property of marine algae on the material
surfaces in the circumferential aspect and in regard of closely
existing of spores and seeds, and so algae can be rooted on the
material surfaces in a relatively short period of a month.
[0411] When algae adhere to and live on the surfaces, the materials
are pulled up for recovery. The materials are transferred as
keeping algae living on the material surfaces to places for
building algae planting places (or improving algae planting
places), and are again immersed as seeding materials. At the same
time, new materials (that is, other materials for adhering marine
algae) are immersed around the seeding materials. Then, for
example, the seeding materials are laid one to two pieces in a
range of around 10 m.times.10 m, and new materials are disposed
around them under a relatively close condition. Further, bases are
built on which new materials are piled, and seeding materials are
laid therein or incorporated in the bases. The inventive method
includes such a case in the embodiments of sinking new materials
around seeding materials.
[0412] In general, places for creating algae planting sites are at
a sea bottom of a depth of 20 m or lower, and the creating work may
be carried out by a procedure of sinking to the sea bottom new
materials conveyed by a ship and not yet adhering marine algae for
making bases, and then suspending seeding materials.
[0413] Properties, tendencies or forms of new materials to be
immersed are similar to those of materials to be the
above-mentioned seeding materials. Different materials in
properties, tendencies or forms may be employed.
[0414] According to such method of creating the algae planting
places, spores or seeds released from algae of the seed materials
adhere to the neighboring materials, grow ordinarily in a
relatively short period of around one year, and form units of
community. Therefore, materials to be adhered with algae are
immersed allover places for planting algae, and among them said
seeding materials are dotted, whereby creation of algae planting
places can be performed easily and in a short term, though be large
scaled places.
[0415] The method of this embodiment may be said to be a method of
creating algae planting place provided with the advantages of the
conventional methods and with further improved advantages. Namely,
the inventive method makes use of an increasing action of marine
algae in existing algae planting places for adhering and rearing
algae in materials to be seeding material for building algae
planting places, and similarly to the conventional methods of
transplanting seeds and saplings to materials, the inventive method
can exactly cause marine algae to root materials, and can create
algae planting places which exactly increase algae in a relatively
short term in comparison with the maintenance free method of
creating algae planting places. In addition, the inventive method
has a merit of widely selecting ranges for making algae planting
places.
[0416] Beside, the method of this embodiment which adheres and
rears algae to materials in sites most suitable for germinating and
growing in the circumstances of algae planting places, so that
algae living on the material surfaces are good in growing and
rooting. Therefore, the present method is high in probability of
surviving and living than the conventional method of transplanting
seeds and saplings of marine algae to materials, and has a big
advantage of scarcely requiring growth management after the
transplanting.
[0417] On the other hand, the method of this embodiment is
different from the conventional maintenance free method of creating
algae planting places only in that materials to be seed materials
are temporarily immersed for a certain period in the existing algae
planting place, and are recovered to be moved to places for
creating algae planting sites, hardly requiring other artificial
works or a growth management of the marine algae. Thus, this method
may be said to have simplicity and economics in cost near to the
conventional maintenance free method of creating algae planting
places.
[0418] Further reference will be made to the suitable materials as
those to be employed in the method of the embodiments.
[0419] As the material (for the seeding material and for the base
creating algae planting places), is an artificially made block of a
main raw material being a slag generated in an iron-steel making
process, where the slag is consolidated with a binder of CaCO.sub.3
or CaCO.sub.3 and MgCO.sub.3 is produced by a carbonation reaction,
and made massive. It is found that such massive block for an algae
planting place does not involve a shortage of oxygen or increase of
pH, and displays excellent effects also in the rearing of marine
algae.
[0420] Further, the artificially massive block can be easily
produced by piling or packing grain like or rough grain like slag
in a desired density and causing a carbonation reaction in the
piled mountain or packed bed under the existence of carbon dioxide,
thereby solidifying grain like or rough grain like slag. The block
material produced by this method can be adjusted to the desired
density and size in response to the conditions of the sea bottom or
ocean currents to be applied, and can be easily made massive.
[0421] Specifically, the above-mentioned artificially made block
has the following advantages.
[0422] Since the main metal content (grain iron) is removed, the
block does not involve a shortage of oxygen in the seawater owing
to oxidation of the iron content.
[0423] Major parts of CaO (or Ca(OH).sub.2 produced from CaO)
contained in the slag are changed into CaCO.sub.3, it is possible
to avoid an increase of pH in the sea water by CaO.
[0424] The massive slag obtained by carbonation-solidifying the
grain like slag and/or the rough grain like slag, has porous
properties as a whole (surface and interior), so that the marine
algae easily attach to the surfaces of blocks. Besides, since the
interior of block is also porous, elements contained in blocks
useful for the growing and accelerating of the algae (for example,
soluble silica or oxidized iron content) are easily dissolved in
the seawater. Therefore, those can effectively accelerate the
growing of the marine algae in comparison with the case of using
massive slags per se for building sea-immersion blocks or concrete
products where the slag is an agglomerate.
[0425] In particular, in the method of this embodiment, it is
necessary to effectively accelerate the adherence and rearing of
algae to the materials temporarily immersed in the existing algae
planting place, the increase and living of algae on the materials
disposed around the seeding materials, and above all to accelerate
the living of young algae on the block surfaces. In this regard,
since useful elements dissolve in the water from the immersion
blocks, such effectively works if individuals of the marine algae
are near thereto, and are very useful to sustain the living of
young algae. Consequently, the useful elements enable the young
algae to promote to breed efficiently, and this invention can
provide higher effectiveness.
[0426] When using massive slags per se as immersion blocks for
algae planting places, because of restraints of cooling methods or
conditions of molten slags, dimensions of the slag are limited
(ordinarily, about 800 mm at maximum), and it is difficult to
provide large massive blocks of regular sizes. On the other hand,
the size of blocks obtained by carbonation solidifying grain like
slag and/or rough grain like slag, can be arbitrarily adjusted by
selecting shapes during carbonation-solidifying or by selecting cut
shapes after the carbonation solidification, and it is possible to
easily obtain large massive blocks particularly suited to algae
planting places.
[0427] It is preferable to use immersion blocks in the sea of an
optimum density (specific gravity) in response to conditions of the
sea bottom or ocean currents. For example, when sinking blocks of a
large density to sea bottoms such as a piling of sludge, the blocks
are immersed into the sludge and cannot serve as bases of algae
places. In this regard, the density of blocks obtained by
carbonation solidifying grain like slag or rough grain like slag
having passed a metal removing treatment, can be arbitrarily
adjusted by appropriately adjusting the bulk density (compaction
density) of the slag during carbonation solidifying.
[0428] As the slags to be main raw materials of the above mentioned
artificially made blocks, there may be enumerated slags from blast
furnaces such as a slowly cooled slag or a water granulated slag
therefrom; slags from an iron-steel making process such as
dephosphorized slag, desulfurized slag desiliconized slag,
decarburized slag or casting slag generated in a pre-treatment, a
converter or casting; slags from iron ore reduction; or slags from
electric furnaces. However, no limit is provided on them. Slags
mixed with two kinds or more of slag may be used.
[0429] In general, the slag generated in an iron-steel making
process contains, a considerable amount of CaO (ordinarily, 20 wt %
to 60 wt %). The artificial block is produced by changing CaO or
Ca(OH).sub.2 changed from CaO contained in grain like slag and/or
rough grain like slag (including CaO and Ca(OH).sub.2 as needed)
into CaCO.sub.3 by the above mentioned carbonation reaction,
consolidating the slag grain (when including the additives, grains
of additives and slag) with a binder of CaCO.sub.3, and making it
massive.
[0430] The major parts of the slag contain a certain amount of MgO
together with CaO. An artificial block where such slag is the raw
material is produced by changing MgO or Mg(OH).sub.2 changed from
MgO (including MgO and Mg(OH).sub.2 as needed) into MgCO.sub.3 by
the above mentioned carbonation reaction, consolidating the slag
grain (when including the additives, grains of additives and slag)
with a binder of MgCO.sub.3 and CaCO.sub.3, and making it
massive.
[0431] Since an artificial block is made by closely consolidating
CaCO.sub.3 or CaCO.sub.3 and MgCO.sub.3 produced by a carbonation
reaction of the slag of a small grain size, the strength is
sufficient, and even if a shock is affected during transportation
or when sinking it in the sea, while being laid in the sea bottom
for a long period, there is almost no possibility that a crack or
destruction will occur.
[0432] An artificial block may contain various kinds of additives
(grain like or rough grain like additives) together with the grain
like or rough grain like slag for providing suitable compositions
in response to conditions of sea areas to be applied therewith. As
the additives, enumerated are, for example, grain or rough grain
(soluble silica, soluble silica containing material) to be a
soluble silica source, grain or rough grain (oxidized iron,
oxidized iron containing material) to be an oxidized iron source,
or CaO of grain or rough grain. For containing CaO as the additive
in the artificial block, it is necessary to leave CaO contained in
slag or at least one part of CaO to be significantly contained in
slag remaining as non-reacted CaO after the carbonation
reaction.
[0433] The soluble silica or the oxidized iron contained in the
artificial block is dissolved in the sea to usefully work to
sustain the living of marine algae. If phosphorus is a cause of red
tide or sulfur is a cause of blue tide are substantially contained
in the sea bottom, CaO contained a bit in the sea immersion block
absorbs these phosphorus or sulfur. As mentioned above, there is a
problem of increasing the pH in the sea water if CaO is
substantially contained in the block, however CaO is sufficient
with a small amount of a degree remaining after the carbonation
solidification for absorbing phosphorus or sulfur.
[0434] As grains or rough grains to be the soluble silica source,
included are the soluble silica and/or the material containing the
soluble silica of the grain or rough grain. As a material
containing the soluble silica, fly ash or clinker ash may be used
which are generated by coal combustion in such as a thermal power
station. The fly ash contains soluble silica in an amount of 45
to-75 wt %, while the clinker ash contains 50 to 65-wt %.
[0435] The water granulated slag from a blast furnace also contains
relatively much soluble silica, and if parts or all of the slag are
rendered to be the water granulated slag, for example, if a slag by
a steel making and the water granulated slag are mixed, a similar
effect is brought about to the case of adding the additive to be a
soluble silica source.
[0436] As the grain or the rough grain to be the oxidized iron
source, included are grain like or rough grain like oxidized iron
and/or an oxidized iron containing material, and in particular,
cheaply available grain or rough grain are iron containing dusts
generated in an iron-steel making process. The iron containing dust
is generally a dust from iron making, and ordinarily contain
oxidized iron of around 75% in terms of Fe. Mill scales also
contain oxidized iron of around 70% in terms of Fe.
[0437] As mentioned above, when sinking blocks of a large specific
gravity to the sea bottom such as a piling of sludge, the blocks
are immersed into the sludge and cannot serve as algae places or
fish gathering places. Therefore, with respect to the block
material to be used for the sea bottom of piled sludge, it is
preferable that a slag of relatively small specific gravity is a
main raw material, and specifically, it is useful to use water
granulated slag of a small specific gravity than that of other slag
as at least one part of the main raw material.
[0438] The artificial block material is relatively porous, thereby
bringing about the above mentioned effects. The percentage of voids
is not especially limited, however normally, around 10 to 70% is a
preferable percentage of voids.
[0439] The artificial block is produced through the same method as
making the sea immersion block explained referring to FIGS. 5 to
8.
EXAMPLE 7
[0440] A mortar was poured into a molding frame of 1.5 m.times.1.5
m.times.1.5 m, and the solidified concrete block was divided into
two by a breaker (rock drill) to produce blocks having fractured
faces for the algae planting place for adherence.
[0441] One of the above blocks was transported to the sea of a
natural algae planting place, put in a pulling-up net, and was
temporarily laid in the algae planting place, turning upward the
fractured face. A period of the seasons for sinking blocks was
selected 9 months just before spending spores from the natural
marine algae planting place in order that sedimentary substances
did not cover the block surfaces before spores adhered thereto.
After about one year, it could be confirmed that algae lived and
rooted on the blocks surface, and the block was pulled up and
transported to the algae planting place as the seeding
material.
[0442] As the algae planting place, taking the water quality and
the ocean current into consideration, a sea bottom of 4 m deep
enough, separated from the existing algae place, was selected. In
this place, 20 pieces of new blocks without adhering algae were
immersed in the range of about 10 m diameter, turning the fractured
faces upward, and at the center thereof, the above mentioned
seeding materials were again immersed.
[0443] After about one year, when this algae planting place was
surveyed, it was confirmed that all the blocks around the seeding
blocks increased the fully living marine algae. The crop estimate
by unit acreage sampling was carried out, and it was found that the
marine algae of 521 g/m.sup.2 in humid weight lived.
EXAMPLE 8
[0444] A converter slag grain like of a grain size of 3 mm or less,
was piled 1.5 m in a pit of 4 m width.times.6 m depth, and
moderately tightened, then the pit was closed and blown with carbon
dioxide 50 Nm.sup.3/hr for 3 days so as to solidify the slag. The
carbonation-solidified slag was broken by heavy machinery to
produce 15 pieces of the massive block materials having a size of
about 1.0 m to 1.5 m for the seeding materials and the bases of the
algae planting place.
[0445] One of the above blocks was transported to the sea of a
natural algae planting place similar to that of the above mentioned
EXAMPLE 3, put in a pulling-up net, and was temporarily laid in the
algae planting place, turning upward the fractured face. A period
of the seasons for sinking blocks was selected 9 months just before
spending spores from the natural marine algae planting place in
order that sedimentary substances did not cover the block surfaces
before spores adhering thereto.
[0446] After about one year, it could be confirmed that algae lived
and rooted on the block surface, and the block was pulled up and
transported to the algae planting place as the seeding
material.
[0447] As the algae planting place, the similar sea area and depth
as the EXAMPLE 3 were selected. In this place, 14 pieces of new
blocks without adhering algae were immersed in the range of about
10 m diameter, turning the fractured faces upward, and at the
center thereof, the above mentioned seeding materials were again
immersed.
[0448] After about one year, when this algae planting place was
surveyed, it was confirmed that all the blocks around the seeding
blocks increased the fully living marine algae. The crop estimate
by unit acreage sampling was carried out, and it was found that the
marine algae of 689 g/m.sup.2 in humid weight lived.
[0449] According to the method of the invention, it is possible to
select wide algae planting places, exactly create the algae places
with less trouble and low cost, and to make algae places of a large
scale.
[0450] Industrial Applicability
[0451] According to the method of the invention, it is possible to
efficiently absorb and remove on an industrial scale CO.sub.2 of
exhaust gas from such as an industrial process by using only an
agglomerate of solid particles as slag or concrete which is easily
available and of low cost. Assuming to use as a CO.sub.2 absorbing
agent (an agglomerate of solid particles) only steel making slag
from the iron-steel slag generated in the iron making firms all
over Japan, and assuming to apply the inventive method to exhaust
gas generated in the iron making firms all over Japan, it is
possible to curtail 1% of the amount of CO.sub.2 generated it may
be said that this reducing amount of CO.sub.2 corresponds to 10% of
the target value of the above mentioned "a 10% reduction in
comparison with 1990 of the energy consumption in the production
process" of the self-imposed behavioral plan in the iron and steel
business world, and corresponds to 24% in comparison with 1995.
Thus, in this sense, this is a very epoch-making invention.
[0452] Further, not only in the reduction of CO.sub.2 for
industrial processes, but also by the method of the invention, it
is possible to select wide algae planting places, exactly create
the algae places with less trouble and at low cost, and to make
algae places of a large scale.
* * * * *