U.S. patent application number 14/431278 was filed with the patent office on 2015-09-17 for method for producing basic products for use as e.g. alkalizing agent (soda lye substitute), for ground stabilization or as filler/pigment.
The applicant listed for this patent is UPM-KYMMENE CORPORATION. Invention is credited to Michael Heberle, Heiko Hilbert, Hendrik Krois, Klaus Muller-Gommert, Johann Oberndorfer, Folke Orsa, Meri Ventola.
Application Number | 20150259767 14/431278 |
Document ID | / |
Family ID | 49253293 |
Filed Date | 2015-09-17 |
United States Patent
Application |
20150259767 |
Kind Code |
A1 |
Hilbert; Heiko ; et
al. |
September 17, 2015 |
METHOD FOR PRODUCING BASIC PRODUCTS FOR USE AS E.G. ALKALIZING
AGENT (SODA LYE SUBSTITUTE), FOR GROUND STABILIZATION OR AS
FILLER/PIGMENT
Abstract
A method for producing basic products from ashes, minerals,
organic solids and other solids, including the provision of a
starting material in particle form, mixing the starting material
with an additive for synthesis and crushing the particles of the
starting material, with a modification of the particles by the
supplied additives for synthesis taking place directly during
crushing, such that the energy-efficient production of a basic
product with a defined particle size and high reactivity is
effected and the produced basic products can be used directly for
further product production, e.g. as alkalizing agent, for ground
stabilization or as filler/pigments.
Inventors: |
Hilbert; Heiko; (Kaufbeuren,
DE) ; Heberle; Michael; (Schongau, DE) ;
Krois; Hendrik; (Schongau, DE) ; Muller-Gommert;
Klaus; (Augsburg, DE) ; Orsa; Folke;
(Lappeenranta, FI) ; Oberndorfer; Johann;
(Puchheim, DE) ; Ventola; Meri; (Lappeenranta,
FI) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
UPM-KYMMENE CORPORATION |
Helsinki |
|
FI |
|
|
Family ID: |
49253293 |
Appl. No.: |
14/431278 |
Filed: |
September 25, 2013 |
PCT Filed: |
September 25, 2013 |
PCT NO: |
PCT/EP2013/069949 |
371 Date: |
March 25, 2015 |
Current U.S.
Class: |
423/155 |
Current CPC
Class: |
C22B 7/006 20130101;
C09C 1/00 20130101; C01P 2004/60 20130101; C05D 9/00 20130101; C09C
1/02 20130101; C09C 3/041 20130101; C09C 1/3018 20130101; C09C 1/40
20130101; C22B 26/20 20130101; C05D 3/02 20130101; D21H 17/67
20130101; C01P 2004/61 20130101; C22B 7/001 20130101; D21H 17/69
20130101; C22B 7/02 20130101; C01P 2004/64 20130101; C01P 2004/62
20130101; B82Y 30/00 20130101; D21H 19/36 20130101 |
International
Class: |
C22B 26/20 20060101
C22B026/20; C22B 7/00 20060101 C22B007/00; C22B 7/02 20060101
C22B007/02 |
Foreign Application Data
Date |
Code |
Application Number |
Sep 25, 2012 |
DE |
102012217302.1 |
Claims
1. A method for producing basic products, comprising the following
steps: i. providing the starting material in particle form, ii.
mixing the particles of the starting material with at least one
additive for synthesis, and iii. crushing the particles of the
starting material, a modification of the particles by the added
additives for synthesis taking place directly during crushing.
2. The method according to claim 1, in which the produced basic
product has an average particle size of 0.01 to 50 .mu.m, in
particular 0.05 to 50 .mu.m.
3. The method according to claims 1 and 2, in which the basic
product is directly used as product, in particular for ground
stabilization, as alkalizing agent, as soda lye substitute, as
adsorption agent and/or as filler/pigment.
4. The method according to one of claims 1 to 3, in which the
starting material provided in step (i) is subjected to a
pre-treatment in which the particles of the starting material are
crushed and/or are separated into at least two fractions with
different average particle sizes.
5. The method according to claim 4, in which to provide the
starting material the crushing of the particles of the starting
material is carried out by pressure waves in the pre-treatment.
6. The method according to claims 4 and 5, in which to provide the
starting material the separation into at least a first fraction
with an average particle size in the range from 0.1 to 8 .mu.m and
a second fraction with an average particle size in the range from 8
to 100 .mu.m is carried out, and the at least two fractions are
provided, independent of each other, as starting material in step
(i).
7. The method according to claims 1 to 6, in which the particles of
the starting material in step (i) are provided in an aqueous
slurry.
8. The method according to one of claims 1 to 7, wherein the
additive for synthesis, which is mixed with the starting material
in step (ii), comprises one or more components selected from gases,
aerosols, liquids and solids which comprise carbon dioxide,
hydrogen fluoride, hydrogen carbonate, hydrogen bicarbonate,
alkylalkoxysilanes or a mixture thereof.
9. The method according to one of claims 1 to 8, wherein in at
least one of the steps (i) to (iii) one or more additives selected
from citric acid, polyacrylates, polyphosphates, polycarbonates,
alcohols, in particular ethanol, isopropanols, alkoxypropanols,
ketones, in particular acetone, amines, in particular
triethylamine, silanes and siloxanes in benzine or isoparrafin,
sulfuric acid, sulfates, in particular lignosulfates, alums, in
particular aluminium sulfate, phosphoric acid, phosphates, soluble
metallic salts, calcium oxide, calcium hydroxide and magnesium
oxide are added.
10. A dispersion produced by dispersing the basic product produced
according to the method according to one of claims 1 to 9 in a
dispersing medium.
Description
TECHNICAL FIELD
[0001] The present invention relates to a method for producing
basic products for use e.g. as alkalizing agent (soda lye
substitute), for ground stabilization or as filler/pigment. The
starting materials can be ashes, calcined basic products, minerals,
organic solids and other solids such as pigments and fibers,
plastic, rubber, etc.
[0002] In particular, the method relates to the energy-efficient
recycling and defined modification of power station ashes, mineral
substances such as marble and solids for further product
production.
BACKGROUND
[0003] Substances such as industrial ashes and incineration ashes
have so far been passed on mainly as waste for utilization
primarily to the building and cement industries. DE 10 2005 029500
A describes, however, that by the indirect use of the high alkali
and alkaline earth oxide contents a substitution of soda lye by
recycled ash as alkalizing agent is used in paper recycling and in
wood pulp bleaching.
[0004] Owing to the material properties of starting materials such
as ashes, which have a large proportion of important components
such as CaO, MgO, Al.sub.2O.sub.3 and Na.sub.2O, the recycling of
waste products to basic products that can be reintroduced into
industrial processes e.g. in paper and wood processing, in ground
stabilization or as filler/pigments is of economic and ecological
interest.
[0005] Processing is, however, necessary inter alia since, due to
their particle size, the starting materials negatively impact the
course of processes. For the recycling of starting materials such
as industrial ashes and incineration ashes, inorganic or organic
solids as well as minerals, conventional methods have so far been
used, in particular milling in a wet process with conventional
milling machines such as ball mills. However, the recycling of
these starting materials has been uneconomic so far due to the high
amount of energy required.
[0006] A further problem of the conventional milling methods is,
however, that in particular in the wet process technical problems
and high downtime often arise, which are caused by the abrasive
wear of the milling tools, deposition and/or cakings in the milling
zone or blockings of the plant.
[0007] This problem is aggravated considerably when using
hygroscopic materials such as ashes or calcined basic products,
which tend to form agglomerates, or even makes recycling of these
substances impossible.
[0008] A further problem of the conventional wet processes is that
they take place under atmospheric conditions, in which air
induction into the milling zone can hardly be prevented and
therefore a reverse reaction (reagglomeration) of the particles
takes place directly during milling. This reverse reaction results
in an increased formation of agglomerates so that a defined
particle size with a homogeneous size distribution of the basic
products cannot be achieved at present or can only be achieved with
a high expenditure of energy e.g. by further process steps. In
particular, it is disadvantageous that due to the reverse reaction
the newly created surfaces of the particles at the same time lose
their reactivity.
[0009] The basic products produced according to conventional
methods therefore have a low quality and can only be reintroduced
into industrial processes to a limited extent.
[0010] These circumstances have so far prevented efficient
recycling of a plurality of starting materials for use as a
marketable basic product and further processing thereof to an end
product.
DESCRIPTION OF THE INVENTION
[0011] Against this background, the invention provides a method
that enables the production of basic products, which have a defined
particle size with a homogeneous distribution and a high reactivity
and which can therefore be integrated in industrial processes,
without requiring a high amount of energy that makes the use
uneconomic.
[0012] The present invention is based on the idea to carry out an
energy-efficient crushing of particles, in which directly before
the crushing the particles are mixed with a specific dosage of an
additive. It is assumed that the particles freshly broken up by the
crushing have the largest possible surface as well as the highest
possible number of reactive surface areas at the time of crushing
and enter a spontaneous reaction on site, i.e. in situ, with
additives for synthesis. In this regard, it is supposed to be
prevented that due an uncontrolled reaction at the resulting
surface a reverse reaction (reagglomeration) takes place. It is
further assumed that with the method according to the invention
controlled, application-related properties of the basic products,
which can also be used for a specific secondary reaction such as
crystallization, are achieved.
[0013] Through intensive studies, the inventors have developed a
method that is suited for the energy-efficient production of
high-quality basic products having a defined particle size.
[0014] In this regard, the average particle size for dry particles
is determined according to ISO 13320 and for wet particles
according to the sedimentation method using x-ray absorption of a
usually aqueous slurry containing the product, which is usually set
to a measurable consistency by dilution with ethanol to prevent the
dissolution of small particles.
[0015] Typically, an average density of 3.0 g/cm.sup.3 is used for
ash, and for the liquid phase owing to the strong dilution the data
of ethanol (density 0.7764 g/cm.sup.3, viscosity 0.9144 mPas) are
used.
[0016] The method will be described in more detail below.
[0017] Within the scope of this invention, reactivity is understood
as the ability of a substance to enter a spontaneous reaction or a
bond at its surface with the medium in which it is located. The
larger the reactive surface, the greater the reactivity of a
substance.
[0018] Within the terms of the present invention, reverse reaction
(also designated as reagglomeration) is understood as a process, in
which a substance loses the state brought about by the milling
process directly after the milling process. In a reverse reaction,
surfaces generated by the milling process for instance can lose
their activity e.g. by reaction with the milling medium or by
repeated formation of agglomerate.
[0019] In the method according to the invention, the starting
materials are provided in an aqueous solution, e.g. as suspension,
dispersion or emulsion, or in the dry state, with the possibilities
described in FIG. 2 e.g. to regulate the pressure, the temperature
or the dry content of the starting materials and to add additives
such as carbon dioxide or reagents to the starting materials.
[0020] Preferably, provision is in the dry state, with the setting
of the temperature and/or the dry content taking place e.g. by
circulation of the starting material by means of a blower. For this
purpose, the starting materials are provided in air or an air/gas
atmosphere, CO.sub.2-containing gases being preferably used.
[0021] The starting materials are all starting materials in
particle form, the method according to the invention being suited
in particular for hygroscopic starting materials.
[0022] In particular, starting materials can be recycled, which are
selected from one or more calcined basic products, inorganic
substances, organic substances, mineral substances and ashes, in
particular paper ashes.
[0023] The ashes comprise all types of incineration ashes and
industrial ashes, particularly preferred ashes being such ashes
which have a high content of CaO, MgO, Al.sub.2O.sub.3, Na.sub.2O
such as e.g. paper ashes or wood ash with a low inert content (e.g.
SiO.sub.2) and/or a low heavy metal content. According to the
invention, the paper ashes comprise ashes from the recycling of
paper/paperboard and their residual substances as well as residues
e.g. after thermal aftertreatment. According to the invention, the
ashes further comprise ashes from burning processes, which
developed at a temperature below or over 850.degree. C.
Furthermore, the ashes can be present preferably in a suspension
with water.
[0024] The starting materials furthermore also comprise mineral
substances, inorganic and/or organic solids. Inorganic substances
comprise preferably calcined substances, which are burnt or
reburnt, particularly preferably marble or calcined clay. Organic
substances comprise preferably pigments, fibers, plastic, rubber,
beans and other solids. Mineral substances comprise preferably
unburnt, burnt or sintered mineral substances, particularly
preferably marble, clay or clay-containing substances, calcium
oxide, calcium hydroxide, magnesium oxide and substances containing
these minerals. The starting materials according to the invention
can also be mixtures of two or more of the above-stated starting
materials, as listed in FIG. 2 under starting materials. Mixtures
with ashes are preferred.
[0025] The starting materials are provided in particle form,
according to the invention the provision of a substance in particle
form meaning a starting material in the form of a particle of any
morphology, preferably the particles have an average particle size
from 0.01 .mu.m to 10 mm, particularly preferably from 0.1 .mu.m to
10 mm and even more preferably from 0.1 .mu.m to 1 mm, the average
particle size for dry and wet particles being determined as
described below in connection with the separation into fine and
finest fractions.
[0026] Preferably the particles of the starting material are
optionally supplemented with additives such as CO.sub.2,
CO.sub.2-containing gases or reagents and precrushed to obtain
predetermined breaking points and hairline cracks, by which the
method according to the invention becomes more efficient in the use
of energy and the crushing of the particles.
[0027] In FIG. 2, this option is illustrated in that the additives
are added to the starting materials before the starting materials
are subjected to precrushing.
[0028] The crushing of the particles of the starting materials is
carried out in both a dry as well as a wet manner by
counterrotating rotors with specific internals depending on the
material to be milled. By this, high-frequency pressure impulses,
(e.g. with a frequency greater than 8 kHz) are created in a high
frequence pressure impulse crusher (hereinafter designated inter
alia as HFPI or as HFPI crusher) with undirected pressure impulses,
in a dry manner preferably under a high airflow, in a
vibration-transmitting medium, which is followed by an in situ
separation, as designated in FIG. 2 as "HFPI crusher with in situ
separation".
[0029] In the HFPI crusher, the crushing of the particles of the
starting material is carried out in a non-contact manner by
pressure waves. High-frequency impact pressure fronts, e.g. with a
frequency greater than 8 kHz, are understood as pressure waves or
also pressure impulses. By using pressure waves, natural frequency
disintegrations, crystal water disintegrations and interactive
stimulation of oscillation between the particles contribute to
crushing and increasing the microporosity of the material to be
milled. The crushing by pressure waves takes places in a
vibration-transmitting medium.
[0030] Such a non-contact milling or disintegration process is
described, for instance, in DE 102 59 456 A1, in which impact
pressure fronts (pressure waves) with an impulse duration of less
than 10 .mu.s and a subsequent frequency of greater than 8 kHz
strike the particles. In this process, the subsequent frequency can
vary. For further details, reference is made to DE 102 59 456
A1.
[0031] A further process for crushing is described, for instance,
in WO 91/07223, which is preferably suited to be able to crush
particles in a wet manner.
[0032] Vibration-transmitting media are liquids such as e.g. water,
water-solvent mixtures, in which one or more solvents are
optionally emulsified, as well as solvent mixtures of two or more
solvents, mixtures of air or air/gas. Particularly preferred media
are mixtures of air, air/gas and/or gas in any combination,
preferred are air/gas mixtures with CO.sub.2-containing gases. If
CO.sub.2 is contained, it is possible to protect the particles from
a reverse reaction by passivation. The crushing of the starting
materials is carried out preferably in the dry state and in
particular under high airflow.
[0033] The execution of the HFPI crushing in the dry manner as well
as in the wet manner can be carried out in one step or in several
steps, several steps in that the HFPI crushing is carried out in
several HFPI crushers connected subsequently in a row or in a
cascade.
[0034] Furthermore, additives are optionally added before, during
or after the crushing, which either directly react with the
particles or which protect the particles e.g. by passivation. The
additives are in particular one or more gases or concentrated
gases, preferably carbon dioxide containing gases, particularly
preferably CO.sub.2-containing waste gases and flue gases from e.g.
thermal power stations, steam power stations and biogas plants.
Similar to that stated above, the addition of carbon dioxide
containing gases or the addition of, for instance, carbon dioxide
containing gases concentrated from waste gases results in the
protection of the particles from a reverse reaction. Moreover, it
is advantageous in terms of environmental technology to use the
waste gases and flue gases from thermal power stations, steam power
stations and biogas plants, which would otherwise have to be
elaborately purified, for this purpose.
[0035] If the crushing is carried out in a dry manner, preferably
moist, CO.sub.2-containing gas or moist, concentrated
CO.sub.2-containing gas are used as additives to use the high
reactivity of the new surfaces and to prevent reverse
reactions.
[0036] Furthermore, the particles crushed in the HFPI crusher can
optionally be used directly for further processing in their present
state or preferably in a dispersion, as designated in FIG. 2 as
"for further processing". A dispersion is preferably prepared by
feeding the particles into a dispersing medium without induction of
foreign air or foreign gas. Precrushing in the HFPI crusher is
particularly energy-efficient, and therefore the energy balance of
the method according to the invention in combination with the HFPI
crusher is particularly favorable. Due to precrushing, the reaction
times in the method according to the invention are moreover
shortened, which results in a potentially higher throughput.
[0037] Furthermore, in a directly subsequent step, the particles
crushed in the HFPI crusher are separated in situ into at least two
fractions which are different in the average particle size.
[0038] Within the scope of this invention, "in situ" is to be
understood as the separation of the particles directly subsequent
to the crushing. This means that there is no procedural gap between
the crushing of the particles and the separation. This has in
particular the advantage that the individual fractions can be
directly used for further processing without further processes
reducing the reactivity of the basic products.
[0039] In the dry process, the separation in an energetic process
is possible without additional energy for a separate module being
necessary (since it is in the same airflow). The dry HFPI process
generates a high air through-put in the particle crushing. This
airflow is used in situ to separate the fine particles in the
subsequent separation in the cyclone (after the expansion of
air/pressure removal). The airflow is subsequently recycled. In a
separate module (e.g. air separator), on the other hand, the
airflow required for this would have to be additionally
generated.
[0040] An immediate and separate storage of the ashes and products
is possible. In this case, the separation is carried out before a
possible interaction (reagglomeration) after the HFPI crusher
without additional filtering. A dispersant or separating agent can
be added in this process as support. The cleaned product of the ash
cooler filter can, depending on the requirements, be added
optionally before the HFPI crusher or directly to the coarser
Cinerit fraction (the term "Cinerit" will be explained later).
[0041] A further advantage is that the applied temperature can be
held and, if necessary, be used for a further production
(modification) step e.g. in a moist medium, without additional
energy having to be supplied. Since the airflow is recycled, no
(cold) fresh air has to be supplied that causes cooling of the
product. Here, on the other hand, a subsequent process e.g. in situ
synthesis crushing (hereinafter also abbreviated as ISC) or
alkalization with warm ash can be carried out. Cooling happens only
when the ash is removed from the system (e.g. by storage in the
silo).
[0042] The separation is carried out e.g. via a cyclone, preferably
via a cyclone with air recycling. Optionally, e.g. additional air
separators are used to enable a further separation of the particles
into additional fractions.
[0043] For the in situ separation of the particles crushed in a wet
manner, preferably separating units, so-called gravity separators,
are used which make use of the centrifugal or gravitational forces.
Examples of such separating units are hydrocyclones (cleaners),
centrifuges or (upstream) classifiers.
[0044] Optionally, additives are added during the separation, which
are selected from the above-stated additives according to the
invention. Preferred additives are CO.sub.2-containing gases or gas
mixtures, preferably CO.sub.2-containing waste gases or flue gases.
A concentration of CO.sub.2 from flue gases and waste gases from
biogas plants is preferably used for some processes (CaCO.sub.3
formation).
[0045] To prevent foreign air induction, the entire system for the
reproduction of the method according to the invention is closed.
Pressure variations are optionally balanced by filter elements.
Pressure, temperature, degree of dryness and atmosphere are
optionally and continuously controlled in the method according to
the invention to optimize the production of the basic products.
[0046] The above-described separation is carried out preferably
into a first fraction, the finest fraction, which has an average
particle size in the range from 0.1 to 8 .mu.m and a second
fraction, the fine fraction, which has an average particle size in
the range from 8 to 100 .mu.m.
[0047] In connection with the separation into the fine and finest
fractions as well as in the entire described method, the average
particle size for the dry particles and/or the basic product is
measured according to ISO 13320. In this case, the determination of
the particle size is based on the physical principles of laser
diffraction. In particular, the HELOS analyzers developed by
Sympatec are used in combination with the RODOS dry dispersing unit
and operated according to the manufacturer's instructions (Sympatec
GmbH, Augsburg, Germany).
[0048] For the determination of the average particle size for the
wet particles and/or the basic product, the sedimentation method is
employed using x-ray absorption of an aqueous slurry containing the
particles, which is usually set to a measurable consistency by
dilution with ethanol to prevent the dissolution of small
particles. Typically, an average density of 3.0 g/cm.sup.3 is used
for ash, and for the liquid phase owing to the strong dilution the
data of ethanol (density 0.7764 g/cm.sup.3, viscosity 0.9144 mPas)
are used. The particle sizes can be determined in particular by
means of a Sedigraph 5100 of Micromeritics, U.S.A. For more
detailed information, reference is made to the operator's manual
(Micromeritics, Sedigraph 5100, Particle Size Analysis System,
Operator's Manual v3.07, 1994).
[0049] The fractions obtained in the separation are optionally
resupplied to the crushing step as often as desired, as designated
in FIG. 2 as "x-fold recycling".
[0050] The obtained fine and finest fractions are optionally used
directly as basic product in the further product production e.g. as
Cinerit.RTM. or Elurit.RTM.. These basic products are designated as
basic products 1+2 in FIG. 2. The basic products 1+2 can be mixed
with other basic products, which is preferably carried out in a
dispersion without induction of foreign air or foreign gas.
[0051] To indicate that the fine and finest fractions can,
independent of each other, provide the respective basic product,
the basic products according to the invention are respectively
designated with two numbers, here "1+2".
[0052] Within the scope of this invention, Cinerit is understood as
the basic product obtained in the fine fraction; Elurit is
understood as the basic product obtained in the finest fraction. In
this case, the finer fraction is separated from the coarser
fraction by in situ air separation in the process without requiring
additional energy in the circulating flow (same airflow).
[0053] There is also the option to unite the starting materials
directly with the particles of the fine and finest fractions
produced in the method according to the invention and thus to avoid
the HFPI crushing with in situ separation, as designated in FIG. 2
as "avoiding HFPI".
[0054] For the method according to the invention, the pretreated
particles are preferably provided in an aqueous slurry. In this
case, aqueous slurries, so-called dispersions, are prepared in that
the pretreated starting materials are fed into an aqueous medium
optionally without induction of foreign air or foreign gas. The
slurries can optionally also contain stabilizers e.g. citric acid,
dispersants e.g. polyacrylates, polyphosphates or polycarbonates,
solvents and solvent combinations, e.g. of alcohols, preferably of
ethanol, isopropanol, alkoxypropanols, of ketones, preferably
acetone, of amines, preferably triethylamine as solvent and
anticorrosive, or of silanes and siloxanes in benzine or
isoparrafin.
[0055] The thus provided starting materials are mixed with at least
one additive for synthesis and are supplied to directly subsequent
crushing. This crushing is carried out in an in situ synthesis
crusher (ISC), in a step as designated in FIG. 2 as "in situ
synthesis crushing".
[0056] According to the invention, "in situ synthesis crushing" is
understood as the crushing of the particles and the reaction of the
thus newly created, reactive surfaces with the previously added
additives for synthesis on site.
[0057] The step of in situ synthesis crushing can comprise wet
milling or dry milling, preferably wet milling. Furthermore, the in
situ synthesis crusher can optionally be followed by a downstream
reactor and/or crystallizer.
[0058] Any gases, aerosols, liquids and/or solids are suited as
additives for synthesis, preferred are such that contain carbon
dioxide, hydrogen fluoride, hydrogen carbonate, hydrogen
bicarbonate, alkylalkoxysilanes or bleaches such as e.g.
H.sub.2O.sub.2 or sodium dithionite or a mixture thereof.
Particularly preferred additives are CO.sub.2-containing gases,
concentrated gases or gas mixtures, preferably CO.sub.2-containing
waste gases or flue gases. The additives for synthesis can be
variably dosed to control the processes such as chemical changes,
settings of the pH value and phase mixtures.
[0059] In the method according to the invention, one or more
additives selected from citric acid, polyacrylates, polyphosphates,
polycarbonates, alcohols, in particular ethanol, isopropanols,
alkoxypropanols, ketones, in particular acetone, amines, in
particular triethylamine, silanes and siloxanes in benzine or
isoparrafin, sulfuric acid, sulfates, in particular lignosulfates,
alums, in particular aluminium sulfate, phosphoric acid,
phosphates, soluble metallic salts, calcium oxide, calcium
hydroxide and magnesium oxide can be added to the additives for
synthesis at any point.
[0060] Furthermore, metallic salts can be used in particular for
controlling the crystal structure.
[0061] The added reagents can also serve to provide reaction
options such as crystallizations, preferably H.sub.3PO.sub.4 being
added for the precipitation of calcium phosphates, lignin
sulfonates for the precipitation of calcium lignin sulfonates and
alums such as aluminium sulfate for the precipitation of calcium
aluminium sulfate (Ca(Al.sub.2[(OH).sub.2(SO.sub.4).sub.2]x 26
H.sub.2O).
[0062] Particularly preferred additives are excipients such as CaO,
Ca(OH).sub.2 or MgO, which are used to optimize the process.
[0063] In the entire process, pressure, temperature, time,
atmosphere and further variables can be set, as clarified in FIG. 2
in the "Variation" box.
[0064] The crushing in the ISC takes place in particular with
milling balls liable to wear, which preferably consist of zirconium
oxide. Depending on the application, the milling ball sizes vary
and possibly also the slot sizes in the milling basket, with the
slot size being smaller than the smallest milling ball. Milling
balls preferably have an average size of 0.1 to 30 mm, preferably
approximately 1-2 mm, determined by the defined sieving and image
analysis assessment.
[0065] If the starting material is provided in a suspension, in the
ISC a surface (36) as smooth and turbulence-free as possible is
created on the suspension (3) by diversion of the product flow by
the flow breakers (6) on the container bottom, which prevents an
undesired induction of air from the air into the suspension (3)
during operation of the plant.
[0066] With continuous operation of the ISC, which is achieved by
additional internals, a statistic factor for only one single
dispersing/milling operation is defined. With this factor, the
possible throughput rate can be determined.
[0067] The execution of the in situ synthesis crushing in the dry
manner as well as in the wet manner can optionally be carried out
in one step or in several steps, several steps in that the in situ
synthesis crushing is carried out in several in situ synthesis
crushers connected subsequently in a row or in a cascade.
[0068] With this milling process, in particular basic products with
a defined particle size and a high, controlled reactivity can be
produced, which preferably have an average particle size with a
lower limit of 0.01 .mu.m, preferably 0.05 .mu.m, particularly
preferably 0.1 .mu.m and even more preferably 0.2 .mu.m, and an
upper limit of 50 .mu.m, preferably 25 .mu.m, particularly
preferably 20 .mu.m and even more preferably 10 .mu.m. In this
regard, the limits of the particles depend on the later use. The
average particle size of the basic products is determined as
described above in connection with the separation into the fine and
finest fractions.
[0069] These basic products, designated in FIG. 2 as basic products
3+4, can directly be further used or be used for mixing with other
basic products.
[0070] The particles obtained after the in situ crushing synthesis
can be supplied as often as desired either to HFPI crushing with in
situ separation or again to the in situ crushing synthesis in the
ISC, as designated in FIG. 2 as "x-fold recycling" after the in
situ crushing synthesis.
[0071] Furthermore, there is the option that the particles of the
fine and finest fractions obtained in the pretreatment avoid the in
situ synthesis crushing, as designated in FIG. 2 as "avoiding ISC".
The particles of the fine and finest fractions, which have avoided
in situ synthesis crushing, are optionally united with the
particles treated in the ISC and thus form the basic products 5+6
in FIG. 2.
[0072] The above-stated additives such as carbon dioxide or carbon
dioxide containing gases or reagents can in turn optionally be
added to the optionally united fractions consisting of the
particles of the in situ synthesis crushing, which are optionally
united with the particles of the fine and/or finest fraction, which
is designated in FIG. 2 as "optional".
[0073] With the particles or united fractions obtained in the above
process, aqueous dispersions can be produced separately and
optionally without air contact or air induction in that the basic
products are fed into an aqueous medium. Furthermore, separating
agents can additionally be added to the obtained fractions or to
the dispersions containing the particles. Furthermore, these
particles or the prepared dispersions can be preferably subjected
to a subsequent milling process for further reduction of the
particle size. These options are also illustrated in a box in FIG.
2.
[0074] To recycle the produced basic products in industrial
applications there is furthermore the option to add additives,
preferably citric acid or potassium chloride and to mix, further
treat or further mill the basic products to obtain thus the basic
products 7+8 of FIG. 2.
[0075] A possible drying of the particles produced according to the
above method results in the basic product 9 of FIG. 2, which can be
mixed, further processed and/or further crushed. The basic products
1-9 can, independent of each other, further be mixed with each
other in any ratio and in any form to produce a basic product of
the method according to the invention.
[0076] All the basic products shown in FIG. 2 or the mixture with
any proportions thereof are optionally used directly in the
building industry for ground stabilization as substitute for burnt
lime. In particular, the basic product obtained from said fine
fraction is used for this.
[0077] Furthermore, the basic products according to the invention
are essentially used directly as alkalizing agents for instance
instead of soda lye (soda lye substitute) in e.g. deinking
processes, for the alkalization of fiber and wood substances and
for the stabilization of wastewater purification plants or as
alkaline adsorption agent instead of lime (DE 10 2005 029 500 A1).
In particular, the basic product obtained from said finest fraction
is used for this.
[0078] Furthermore, the basic products are essentially used
directly as adsorption agent, as filler, in particular as paper
filler, as pigment, as plaster, in composites/synthetics, in fiber
plates, as binders and/or as jointing material.
[0079] One advantage of the present invention is that the
production of the basic products is particularly energy-efficient.
For instance, in the production of CaO-based components via the
burnt lime process (PCC production via Ca(OH).sub.2) according to
conventional methods approximately 1250-1300 kWh/t as well as
approximately 200 kWh/t for the subsequent milling, i.e. in total
approximately 1500 kWh/t, are necessary, whereas by comparison only
110 kWh/t are required for the basic product production according
to the invention.
[0080] A further unexpected advantage of the invention is that
particles with physical-chemical advantages are obtained, which
cannot be obtained with conventional methods. For instance, new
interior surfaces are formed for the produced particles due to an
increase of the material diffusion by increasing the microporosity,
in which water and other reactive substances such as e.g. CO.sub.2
(dissolved or gaseous) can be diffused. Through processes such as
hydration, carbonation, sulfation, etc. an increase in volume and
interior disintegrations due to the volume pressure in the
particles occur. Through these chemical reactions, an additional
particle crushing of the starting material takes place.
[0081] The basic products produced by the invention thus have a
defined formation of exterior and interior surfaces, the increased
reactivity of which can furthermore be used by in situ synthesis
and thus results in particles with increased quality.
[0082] The basic products produced according to the invention have
e.g. an increased degree of whiteness vis-a-vis the conventional
method of wet milling, which indicates that reactive and/or latent
sites are exposed, which can be reacted with additives and reagents
such as CO.sub.2. A particular advantage of the method according to
the invention is the production of basic products with defined
particle size distribution for the definition of specific
properties for basic or end products e.g. the definition of the
paper properties (gloss, whiteness, opacity, printability,
strengths, integration of the paper structure) or the definition of
the surface structure for water absorption and setting of ground
materials in ground stabilization.
[0083] A particular advantage is moreover that the increased
reactivity, which is obtained in the precrushing of the starting
materials e.g. in the HFPI crusher, can be used by the method
according to the invention.
[0084] A further advantage of this invention is that an agglomerate
or aggregate formation, which occurs in the crushing according to
conventional methods with grinding units such as ball mills, does
not take place or only takes place to a very minor extent. This
provides technical advantages in the recycling process, since e.g.
almost no machine downtimes are caused by deposition, cakings or by
abrasive wear of the milling tool.
[0085] By preventing the agglomerate formation, basic products with
a defined particle size, i.e. a defined average particle size and
defined maximum particle size, are moreover obtained with the
method according to the invention. When these basic products are
reintroduced into industrial processes, they do not generate a
disruption of the industrial process steps which occur e.g. with
particles and agglomerates having a too large diameter.
[0086] Hereinbelow, unrestrictive examples are provided, which
serve as clarification of the invention.
BRIEF DESCRIPTION OF THE DRAWINGS
[0087] FIG. 1 shows a sketch of the principle of the in situ
synthesis crusher that is suited for carrying out the method
according to the invention.
[0088] FIG. 2 schematically shows possible workflows of the method
according to the invention for the production of basic
products.
[0089] FIG. 3 shows a test set-up of a plant for providing the
starting material for the method according to the invention.
EMBODIMENT EXAMPLES
In Situ Synthesis Crushing
[0090] According to FIG. 1, the particles of the starting material
are subjected to crushing in an in situ synthesis crusher (1) (also
ISC), with an additive for synthesis (32) being supplied directly
into the milling zone of the ISC and foreign air induction during
milling being prevented. This takes place in a container (1) of a
ring chamber dispersing mill with slot lengths and widths defined
depending on the product requirements, which is filled with the
starting material (3) via the filler inlet (4). Owing to the
rotation of a propeller (11), the starting material (3) is
transported uniformly from the surface downwardly into the center.
This product flow moves through the inlet tube (17) of the stator
to directly before the dispersing disk (13), where it is deflected
radially outwards (15) and is set into rotation by the blades (14)
of the dispersing disk (13). At the edge of the dispersing disk
(13), the product flow (24) absorbs the additives (32) and enables
a synthesis between the additives (32) and the particles (28)
carried along in the product flow. The product flow flows into the
hollow space (22) of the ring chamber (21), with high shear forces
occurring within the product flow in the transition from the
rotating dispersing disk (13) to the stationary ring chamber (21).
These shear forces on the one hand cause the dispersion of the
product and the dissolution of present agglomerates and on the
other hand ensure that the additive for synthesis can be optimally
absorbed by the product suspension (3). In the hollow space (22) of
the ring chamber (21) the actual milling takes place, by which
individual product particles, which are caught between two milling
balls clashing at high speed, are broken up. In part, the milling
also takes place directly at the interior wall of the ring chamber
(21), where particles (29) are hit by striking milling balls (27).
The product is deflected radially outwards (26) by the flow (24)
through the slots (25) in the ring chamber, where the flow
direction is diverted again upwardly to the surface by the double
conical container base (2). Due to repeated suction of the
suspension (3) by the propeller (11), the cycle is kept running
until the desired degree of milling of the particles (29) is
achieved and the product is released.
Provision of the Starting Material by Upstream HFPI Crushing and In
Situ Separation
[0091] The starting material ash is supplied from a silo (1)
(hereinafter referring to FIG. 3) as starting material for
temperature setting in an ash cooler. The ash is circulated with a
blower in the ash cooler (2) and, if necessary, the temperature is
reduced from approximately 140.degree. C. to 70.degree. C. by means
of cooling water. The thus whirled up and cooled ash is supplied
via a rotary feeder into the tube chain conveyor (5). The exhaust
air is purified of finest particles via a reverse flow cartridge
filter (3). The finest particles are supplied to the finest
fraction (8), which is downstream of the crushing, via a valve.
[0092] The supply to the HFPI crusher (6) is carried out
consistently via chain conveyor (5). The entire system is closed,
pressure variations are compensated by a filter element at this
point.
[0093] The crushing in the HFPI crusher (6) is carried out by means
of counterrotating rotors with specific internals adapted according
to the required basic or end product in an air atmosphere under
high airflow.
[0094] The ash crushed in a non-contact manner is separated in a
subsequent step into a fine fraction (8) (Cinerit) and a finest
fraction (9) (Elurit) without a procedural gap, i.e. in situ. The
separation into fine fraction and finest fraction is carried out
via a cyclone. In the finest fraction (9), there is an air
recycling (7) to the HFPI crusher. In the recirculation line, a
further filter element is located which can be optionally connected
to the existing exhaust air filter system and serves for pressure
compensation.
[0095] Ash, which corresponds to the properties of the fine
fraction and is yielded in a filter (3) during ash cooling, can
optionally be directly supplied to the Cinerit container (8).
[0096] There is the option to supply the separated fractions to a
silo (12) via an ash dispenser (10) and (11) and store these
temporarily for further use. There is also the option to fill the
fine fraction (Cinerit) and the finest fraction (Elurit) in
separate silos (13) or (14) (Cinerit/Elurit).
[0097] Directly from the Cinerit (8) or Elurit (9) containers, the
corresponding ash dispensers (10) or (11) or from the corresponding
silos (12), (13) or (14), the fine and/or finest fraction is
optionally suspended with water and dispersed in a dissolution
plant, transported to the ring chamber dispersing mill (1)
(hereinafter referring to FIG. 1) and filled into the ring chamber
dispersing mill (1) via the filler inlet (4). The in situ synthesis
crushing according to the invention follows.
Comparison of the Required Energy
[0098] The energy required to produce fillers/pigments according to
the conventional burnt lime process is compared to the method
according to the invention in Table 1.
[0099] The energy for the filler/pigment production according to
the conventional burnt lime process is calculated via the sum for
providing the basic product CaCO.sub.3, which is stoichoimetrically
calculated in relation to the CaO input, and the energy required
for the wet milling of Ca(OH).sub.2 from CaO. The additional energy
for transport and slaking is not included in the calculation.
[0100] The energy for the method according to the invention is
calculated from the combination of the energy required for the
low-energy pretreatment in the HFPI crusher and for the crushing in
the in situ synthesis crusher according to the method according to
the invention.
TABLE-US-00001 TABLE 1 Production of Fillers/Pigments Required
Energy (90% < 2 m) kWh/t Ash Conventional burnt lime process 840
Method according to the invention as 80* combination of HFPI
crusher and ISC (*the advantage of the lower amount of CO.sub.2
required during synthesis is not included in the calculation)
Comparative Examples
[0101] In the following embodiment examples, ash is used as
starting material. The ash, on which the following examples are
based, is obtained in a 56 MW thermal power station with a
fluidized-bed boiler by incineration of fiber residues (fibers
yielded as loss in the waste paper recycling system) as well as
waste wood and sawdust. Furthermore, removed color particles and
sorted-out synthetic materials from the waste paper are contained
in the material to be incinerated. The ash essentially consists of
approximately 48% CaO (free lime content approximately 8%), 5% MgO,
14% Al.sub.2O.sub.3, 1% Na.sub.2O, 0.2% K.sub.2O, 35% SiO.sub.2 and
typical minor components of ash, as determined by X-ray
fluorescence analysis.
Example 1
Ash Recycling According to the Method According to the
Invention
[0102] The starting material ash is provided by the crushing in the
HFPI crusher, which is carried out by means of counterrotating
rotors with specific internals in an air atmosphere under high
airflow. The in situ synthesis crushing is subsequently carried out
according to the above-described method according to the invention
in the presence of the additive for synthesis CO.sub.2, added as
99.9% CO.sub.2 gas (Linde gas cylinder).
Comparative Example 1
[0103] In Comparative Example 1, the ash recycling is carried out
according to Example 1, with the difference that CO.sub.2 is not
present during the process.
Comparative Example 2
[0104] Ash Recycling According to Conventional Methods Recycling
the ash according to conventional wet milling (MW 2 .mu.m)
Comparative Example 3
[0105] In Comparative Example 3, the ash recycling is carried out
according to Comparative Example 2, with the difference that
CO.sub.2 is present during the process.
Properties of the Produced Basic Products
[0106] The properties of the produced basic products were
determined as follows:
[0107] The degree of whiteness was determined after reaction of the
product with air and the CO.sub.2 contained therein. The optical
properties of the degree of whiteness R457 were determined by means
of an L&W Elrepho/pulsed xenon lamp with D65 diffuse standard
illuminant and 10.degree. viewing.
[0108] Determination of the specific surface (BET) of solids
according to DIN 66132, according to BET method, DIN EN ISO 18757
(previously: DIN EN 725-6) with AREA-meter II (Strohlein
Instruments) according to Haul and Dumbgen.
[0109] The properties of the basic products from Examples 1 and 2
as compared to the basic product produced according to Comparative
Examples 1 and 2 are listed in Table 2 and the properties of the
particles, which are obtained via the conventional burnt lime
process for the production of PCC (CaCO.sub.3 from CaO,
precipitated calcium carbonate), are compared.
TABLE-US-00002 TABLE 2 Compar- Compar- Compar- PCC from Reference
ative ative ative burnt lime Example Example 1 Example 1 Example 2
Example 3 process BET [m.sup.2/g] 16.2 12 4.4 -- 16.9 Degree of
85.4 74.5 71.1 78.2 95.5 whiteness D65/10.degree. [%]
[0110] It is apparent from Table 2 that due to the method according
to the invention starting from the starting material a significant
increase of the specific surface and thus also an increase of the
specific reactive surface is achieved, which is apparent here from
the larger BET surface area and the increased degree of whiteness.
It can moreover be seen that according to the method according to
the invention basic products are produced, which have comparable
properties as the PCC produced according to the conventional burnt
lime process, however, as shown in Table 1, requiring significantly
less energy.
Examples of Use
Use of Ash as Soda Lye Substitute
[0111] In an aqueous dispersion, the ash that has been recycled
using the method according to the invention can, as an alkaline
component, replace the use of soda lye by using the alkali and
alkaline earth oxide contents, e.g. in paper and wood
production.
Use of Fine Particle Ash for Use in Ground Stabilization
[0112] The prerequisite for the use of ash in ground stabilization
is a defined degree of particle size, which can only be achieved
with the method according to the invention, but not with
conventional methods such as ball mills.
[0113] The ash product according to the invention replaces burnt
lime (CaO) here in ground stabilization, as a result of which it is
possible to reduce the amount of energy required from
conventionally 1391 kWh/t to only 80 kWh/t according to the
invention.
Use of Ash as Filler/Pigment in Paper Production
[0114] The ash according to the invention can be used directly as
filler in paper production by direct substitution of chalk/kaolin
or indirectly by substitution of burnt lime in PCC processes
(precipitated calcium carbonate).
* * * * *