U.S. patent application number 13/583570 was filed with the patent office on 2013-02-14 for melting method and recycling method for collected printing plates.
The applicant listed for this patent is Masakazu Osada, Toru Yamazaki. Invention is credited to Masakazu Osada, Toru Yamazaki.
Application Number | 20130036867 13/583570 |
Document ID | / |
Family ID | 44563337 |
Filed Date | 2013-02-14 |
United States Patent
Application |
20130036867 |
Kind Code |
A1 |
Osada; Masakazu ; et
al. |
February 14, 2013 |
MELTING METHOD AND RECYCLING METHOD FOR COLLECTED PRINTING
PLATES
Abstract
Since oxidation loss can be reduced even if collected printing
plates are directly melted together with fresh ingots, a high
melting yield approximately equal to a melting yield in the case of
melting recycled ingots can be obtained. The present invention is a
melting method for melting collected printing plates 35 and fresh
ingots 37 by a burner 19 in a melting furnace 13, the collected
printing plates 35 being collected used lithographic printing
plates 36 and/or scraps 33 including offcuts of lithographic
printing plates, the method including a first injection step of
firstly injecting the collected printing plates 35 in the melting
furnace 13 such that a pile of the collected printing plates 35 is
formed on a hearth 13B of the melting furnace 13, and a second
injection step of injecting the fresh ingots 37 on the pile of the
collected printing plates 35 so as not to substantially expose the
pile, wherein the fresh ingots are melted in flames of the
burner.
Inventors: |
Osada; Masakazu;
(Haibara-gun, JP) ; Yamazaki; Toru; (Haibara-gun,
JP) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Osada; Masakazu
Yamazaki; Toru |
Haibara-gun
Haibara-gun |
|
JP
JP |
|
|
Family ID: |
44563337 |
Appl. No.: |
13/583570 |
Filed: |
February 23, 2011 |
PCT Filed: |
February 23, 2011 |
PCT NO: |
PCT/JP2011/053945 |
371 Date: |
September 7, 2012 |
Current U.S.
Class: |
75/414 |
Current CPC
Class: |
Y02P 10/20 20151101;
B41N 1/083 20130101; C22B 21/06 20130101; F27B 3/10 20130101; B41N
3/006 20130101; C22B 7/003 20130101; C22B 21/0092 20130101; Y02P
10/218 20151101; F27B 3/205 20130101 |
Class at
Publication: |
75/414 |
International
Class: |
C22B 9/16 20060101
C22B009/16 |
Foreign Application Data
Date |
Code |
Application Number |
Mar 10, 2010 |
JP |
2010-053254 |
Claims
1. A melting method for melting collected printing plates which
melts collected printing plates and fresh ingots by a burner in a
melting furnace, the collected printing plates which are collected
used lithographic printing plates and/or scraps including offcuts
of lithographic printing plates, the method comprising: a first
injection step of firstly injecting the collected printing plates
in the melting furnace to form a pile of the collected printing
plates on a hearth of the melting furnace; a second injection step
of injecting the fresh ingots on the pile of the collected printing
plates so as to cover the pile and not to expose, wherein; and a
melting step of melting the fresh ingots by exposing the fresh
ingots to flames of the burner.
2. The melting method for collected printing plates according to
claim 1, wherein the melting furnace is a pre-rolling melting
furnace of an aluminum rolling company.
3. The melting method for collected printing plates according to
claim 1, wherein an oxygen concentration in the melting furnace
during the melting step is 11% or less.
4. The melting method for collected printing plates according to
claim 3 wherein the oxygen concentration is 6% or less.
5. The melting method for collected printing plates according to
claim 1, wherein the melting furnace has an airtight structure
having a chimney provided with a damper, and smoke ventilation
control is performed by opening and closing the damper so as to
make an internal pressure in the melting furnace higher than an
external pressure of the melting furnace.
6. A recycling method for recycling collected printing plates which
are collected used lithographic printing plates and/or scraps
including offcuts of lithographic printing plates to reuse the
collected printing plates as aluminum raw material for a support
for a lithographic printing plate, wherein the collected printing
plates are directly melted together with fresh ingots in a
pre-rolling melting furnace of an aluminum rolling company without
making the collected printing plates as a recycled ingot, and the
melting method according to claim 1 is applied to the direct
melting.
Description
TECHNICAL FIELD
[0001] The present invention relates to a melting method and a
recycling method for collected printing plates, and in particular
to a technique to improve a melting yield when collected printing
plates are directly melted in a pre-rolling melting furnace in an
aluminum rolling company.
BACKGROUND ART
[0002] A lithographic printing plate is manufactured by forming a
plate making layer (for example, a photosensitive layer) on a
roughened, aluminum support for a lithographic printing plate.
Roughening methods include mechanical roughening, electrochemical
roughening, chemical roughening (chemical etching), and
combinations thereof, and a highly pure fresh ingot needs to be
used as an aluminum raw material when the surface of the support is
uniformly and finely roughened, and the content of trace metals,
such as Si, Fe, Cu, and Mn, needs to be strictly adjusted.
[0003] Conventionally, therefore, it is difficult to use used
lithographic printing plates (aluminum scraps) as an aluminum raw
material for the support for a lithographic printing plate, and in
reality the used lithographic printing plates (aluminum scraps) are
recycled as a raw material for applications in which a content
tolerance of trace metals is large, for example, for a window sash,
an automotive engine, or a vehicle wheel.
[0004] Manufacture of 1 kg (one kilogram) of fresh ingot, however,
requires large energy such as 140.9 MJ, where a CO.sub.2 emission
amount which causes global warming is very large such as 9.22 kg
per 1 kg ingot. On the other hand, when used lithographic printing
plates which were used for printing or collected scraps such as
offcuts which were generated in the course of manufacture of
lithographic printing plates are used as raw materials, the energy
for manufacturing 1 kg of recycled ingot is approximately 4% when
the energy for manufacturing one kg of fresh ingot is assumed to be
100%, and the amount of CO.sub.2 emission in manufacturing such a
recycled ingot is also very small such as approximately 4% of the
amount of CO.sub.2 emission in manufacturing a fresh ingot.
[0005] In order to manufacture an aluminum raw material for a
support for a lithographic printing plate with low energy,
therefore, it is important to recycle collected printing plates as
recycling materials.
[0006] In recent years, remelting collected printing plates to
recycle the collected printing plates as an aluminum raw material
for a support for a lithographic printing plate has been discussed,
which is shown, for example, in Patent Document 1.
[0007] In Patent Document 1, a recycled ingot is made by melting
collected printing plates, and an precursor for a support for a
lithographic printing plate is then manufactured by mixing this
recycled ingot in a fresh ingot, melting the mixture and rolling it
into a thin plate.
CITATION LIST
Patent Literature
[0008] Patent Document 1: WO 2009/084568
SUMMARY OF THE INVENTION
Technical Problem
[0009] However, when collected printing plates are melted in order
to make a recycled ingot and the recycled ingot and a fresh ingot
are further melted like Patent Document 1, it means that melting is
performed twice, which causes a problem of energy inefficiency.
Therefore, by melting collected printing plates directly in a
pre-rolling melting furnace in an aluminum rolling company, the
energy efficiency is significantly improved.
[0010] However, a collected printing plate, in particular, a used
lithographic printing plate has an area approximately equal to the
area of a sheet of newspaper and has a thin-plate-like shape
(approximately 0.1 to 0.4 mm). Since the lithographic printing
plate has a large surface area, oxidative loss due to combustion or
the like becomes very large when the lithographic printing plate is
directly melted in a pre-rolling melting furnace in an aluminum
rolling company. It should be noted that directly melting collected
printing plates without making a recycled ingot from the collected
printing plates is referred to as "direct melting".
[0011] As a result, there is the problem that when melting a
recycled ingot, a melting yield of approximately 97% is achieved,
which is nearly equal to the melting yield of a fresh ingot;
however, when melting collected printing plates, a melting yield of
just approximately an 80% to 85% is achieved. Furthermore, since
the pre-rolling melting furnace is designed to melt an ingot, such
as a recycled ingot or a fresh ingot, which requires high melting
temperature, the melting furnace is of a direct burner flame
heating type to melt an ingot by direct burner flame. Therefore,
directly melting collected printing plates without making a
recycled ingot from the collected printing plates further
facilitates oxidation, which results in melting yield
degradation.
[0012] The present invention has been made in view of these
circumstances, and the present invention aims to provide a melting
method and a recycling method for collected printing plates, where
oxidation loss can be reduced even if collected printing plates are
directly melted together with fresh ingots, so that a high melting
yield approximately equal to the melting yield in the case of
melting a recycled ingot can be obtained.
Solution to Problem
[0013] In order to achieve the above object, a melting method for
collected printing plates according to the present invention is a
melting method for melting collected printing plates which melts
collected printing plates and fresh ingots by a burner in a melting
furnace, the collected printing plates which are collected used
lithographic printing plates and/or scraps including offcuts of
lithographic printing plates, the method comprising: a first
injection step of firstly injecting the collected printing plates
in the melting furnace to form a pile of the collected printing
plates on a hearth of the melting furnace; and a second injection
step of injecting the fresh ingots on the pile of the collected
printing plates so as to cover the pile and not to expose, wherein
the fresh ingots are exposed flames of the burner to be melted.
[0014] According to the melting method of the present invention,
the collected printing plates, which have thin-plate-like shape
having a large surface area and are easily oxidized, are covered
with the fresh ingots, which are difficult to oxidize because of
its shape, and then the fresh ingots are melted is exposed to
flames of the burner to be melted. This causes firstly the fresh
ingot to melt into molten metal, and then the collected printing
plates are indirectly melted by the molten metal. Further, the
collected printing plates are melted in a state where the collected
printing plates are soaked (immersed) in molten metal of the fresh
ingots, and therefore the collected printing plates can be
prevented from coming into contact with air during melting. Thus,
oxidation loss can be significantly reduced even in the case of
melting the easy-to-oxidize collected printing plates.
[0015] In present invention, the melting furnace is preferably a
pre-rolling melting furnace of an aluminum rolling company. In the
pre-rolling melting furnace of an aluminum rolling company, the
content of trace metals in an aluminum sheet to be manufactured is
required to be adjusted according to the intended purpose of the
aluminum sheet. Therefore, it is necessary to melt the collected
printing plates together with the fresh ingots, and thus the
present invention can be effectively used.
[0016] In the present invention, the oxygen concentration in the
melting furnace during the melting is preferably 11% or less, more
preferably 6% or less.
[0017] Methods for making an 11% or less oxygen concentration in
the melting furnace include air-fuel ratio control or smoke
ventilation control. That is, it is preferred that an air-fuel
ratio which is a ratio of an air flow rate to a fuel flow rate of
the burner, is controlled so as not to generate excess oxygen in
the furnace.
[0018] By controlling the air-fuel ratio to come as close to a
theoretical air-fuel ratio as possible so as to prevent excess
oxygen from being generated in the furnace, the oxygen
concentration in the melting furnace can be made low, and thus the
oxidation loss during melting can be further reduced.
[0019] Further, in the present invention, it is preferred that the
melting furnace has an airtight structure having a chimney provided
with a damper, and smoke ventilation control is performed by
opening and closing the damper so as to make the internal pressure
in the melting furnace higher than the external pressure
thereof.
[0020] Since the melting furnace has an airtight structure, and
smoke ventilation control is performed such that the internal
pressure of the melting furnace becomes higher than the external
pressure thereof, air is prevented from entering the melting
furnace from outside of the melting furnace, and therefore the
oxygen concentration in the melting furnace can be made low. This
makes it possible to further reduce the oxidation loss during
melting.
[0021] In order to achieve the above object, a recycling method for
recycling collected printing plates which are collected used
lithographic printing plates and/or scraps including offcuts of
lithographic printing plates to reuse the collected printing plates
as aluminum raw material for a support for a lithographic printing
plate, wherein the collected printing plates are directly melted
together with fresh ingots in a pre-rolling melting furnace of an
aluminum rolling company without making the collected printing
plates as a recycled ingot, and the melting method according to any
one of claims 1 to 5 is applied to the direct melting.
[0022] According to the recycling method of the present invention,
a high melting yield can be obtained, unlike a conventional method,
without making the collected printing plates into a recycled ingot
and then melting the recycled ingot in a pre-rolling melting
furnace of an aluminum rolling company. This makes it possible to
omit a conventional step of temporarily recycling the collected
printing plates into recycled ingots, thereby melting of the
collected printing plates is performed only once in the pre-rolling
melting furnace. Therefore, the energy efficiency of recycling the
collected printing plates into aluminum raw material for a support
for a lithographic printing plate can be remarkably improved.
Advantageous Effects of Invention
[0023] According to the melting method and the recycling method for
collected printing plates of the present invention, since the
oxidation loss can be reduced even if the collected printing plates
are directly melted together with the fresh ingots, a high melting
yield approximately equal to a melting yield obtained in the case
of melting the recycled ingots can be obtained. This makes it
possible to omit a conventional step of temporarily making the
collected printing plates into recycled ingots, thereby melting the
collected printing plates only once in a pre-rolling melting
furnace. Therefore, the energy efficiency of recycling the
collected printing plates into aluminum raw material for a support
for a lithographic printing plate can be remarkably improved.
BRIEF DESCRIPTION OF DRAWINGS
[0024] FIG. 1 is an illustrative drawing for illustrating a melting
method for collected printing plates according to an embodiment of
the present invention;
[0025] FIG. 2 is an illustrative drawing for use in comparison with
the melting method of the embodiment;
[0026] FIG. 3 is an illustrative drawing for illustrating a method
for recycling collected printing plates according to the present
invention; and
[0027] FIG. 4 is an illustrative drawing for illustrating a
conventional method for recycling collected printing plates.
DESCRIPTION OF EMBODIMENTS
[0028] Hereinafter, preferred embodiments of a melting method and a
recycling method for collected printing plates of the present
invention will be described in detail.
[0029] FIG. 1 is an illustrative drawing conceptually showing a
melting method for collected printing plates in accordance with an
embodiment of the present invention, and FIG. 2 is an illustrative
drawing for use in comparative explanation with the present
invention.
[0030] As shown in FIG. 1, a melting apparatus 11 has a slot 15
through which an object to be melt is inserted is opened in a side
wall of a melting furnace 13, and the slot 15 is provided with an
opening-and-closing door 17. In this case, it is preferred that the
slot 15 is provided with a packing and the opening-and-closing door
17 has a seal structure.
[0031] A plurality of burners 19 are attached to a ceiling 13A of
the melting furnace 13, and flames 21 blast out from the burners 19
melt the object to be melt put in the melting furnace 13. The
burners 19 are fed with fuel and air through piping 23, and in the
middle of the piping 23, an air-fuel ratio control device 25 which
controls an air-fuel ratio which is a ratio between fuel and air is
provided.
[0032] A chimney 27 is attached to the ceiling 13A of the melting
furnace 13 so that smoke generated by melting is discharged. The
chimney 27 is provided with a damper 29, by which the opening area
of the chimney 27 can be varied so that the volume of discharged
smoke can be controlled.
[0033] The burners 19 and the damper 29 are connected to a
controller 31 by a signal cable or wirelessly, and the air-fuel
ratio of the burner 19 and the volume of discharged smoke of the
damper 29 are controlled by the controller 31.
[0034] Next, using the melting apparatus 11 thus configured, the
melting method for collected printing plates of the present
invention will be described.
[0035] Collected printing plates 35 and fresh ingots 37, which are
the objects to be melted, are put in the melting furnace 13 through
the slot 15. Here, a collected printing plate 35 means a used
lithographic printing plate which has been used in printing and/or
scraps such as offcuts of a lithographic printing plate that are
generated in the course of manufacture of a lithographic printing
plate.
[0036] When injecting (putting in) the objects to be melted, first,
the collected printing plates 35, each of which has a large surface
area and is thus easily oxidized, are put in the melting furnace 13
such that a pile of the collected printing plates 35 is formed on a
hearth 13B (first injection step).
[0037] Next, the fresh ingots 37 are put in on the pile of the
collected printing plates 35 such that the fresh ingots 37 cover
the pile so as not to expose the pile substantially (second
injection step).
[0038] Though, in FIG. 1, for the purpose of easy-to-understand
description, the collected printing plates 35 is exposed, in
reality the collected printing plates 35 are covered with the fresh
ingots 37 so as not to be substantially exposed. It should be noted
that the condition that the pile is not substantially exposed does
not mean that the pile is essentially required to be covered
completely, but means that the pile is just required to be covered
apparently. The individual fresh ingot 37 is, preferably, a
relatively small ingot having a weight of approximately 5 to 10 kg.
This is not only because smaller ingots are less likely to damage
the hearth 13b when injecting, but also because smaller ingots can
easily cover the pile of the collected printing plates 35 so as not
to expose. In this state the fresh ingots 37 are the melted by the
flames 21 of the burners 19.
[0039] This causes the fresh ingots 37, each of which has a small
surface area and is thus difficult to oxidize, to melt into molten
metal, and the molten metal indirectly melts the collected printing
plates 35. Accordingly, even a thin collected printing plate which
has a large surface area and is thus easily oxidized can be
effectively inhibited from oxidizing during melting, and therefore
the oxidation loss of the collected printing plates 35 can be
significantly reduced.
[0040] On the other hand, as shown in FIG. 2, in a case where the
fresh ingots 37 are first put in the melting furnace 13 such that a
pile of the fresh ingots 37 is formed, and the collected printing
plates 35 are then put in so as to cover the pile of the fresh
ingots 37, the easy-to-oxidize collected printing plates 35
directly contact with (are exposed to) the flames 21 of the burners
19. This facilitates formation of aluminum oxide, and therefore the
oxidation loss of the collected printing plates 35 increases
significantly.
[0041] Actually, when the melting method of the present invention
in FIG. 1 and the melting method in FIG. 2 were performed with the
same blend ratio of the fresh ingots 37 to the collected printing
plates 35, the melting yield obtained by the melting method in FIG.
2 was 80% to 85%, whereas the melting yield obtained by the melting
method in FIG. 1 was 88% to 95%. It should be noted that, in a case
where the collected printing plates 35 and the fresh ingots 37 are
randomly put in the melting furnace 13, the percentage of exposure
of the collected printing plates 35 to air is high, as compared
with the melting method of the present invention, and therefore the
oxidation loss also increases.
[0042] Further, in order to further improve the melting yield, the
oxygen concentration in the melting furnace 13 during melting is
preferably 11% or less, more preferably 6% or less.
[0043] As a method for suppressing the oxygen concentration in the
melting furnace 13 to 11% or less, air-fuel ratio control and smoke
ventilation control are preferred.
[0044] That is, the controller 31 controls the air-fuel ratio
control means 25 so as not to generate excess oxygen in the melting
furnace 13. Thus, by performing air-fuel ratio control to make the
air-fuel ratio as close to a theoretical air-fuel ratio as possible
so as to prevent excess oxygen from being generated in the melting
furnace 13, the oxygen concentration in the melting furnace 13 can
be made low.
[0045] Further, the controller 13 controls the damper 29 provided
in the chimney 27 so as to perform smoke ventilation control to
make the internal pressure of the melting furnace 13 higher than
the external pressure thereof. This can prevent air from entering
the melting furnace 13 from outside of the melting furnace 13, and
therefore the oxygen concentration in the melting furnace 13 can be
made low.
[0046] Therefore, by performing the air-fuel ratio control and the
smoke ventilation control, the oxidation loss of the collected
printing plates 35 can be further reduced.
[0047] Next, a recycling method for collected printing plates of
the present invention will be described in comparison with a
conventional recycling method therefore.
[0048] FIG. 3 shows a recycle loop of the present invention, in
which a collected printing plate is recycled to be reused as an
aluminum raw material for a support for a lithographic printing
plate, and FIG. 4 shows a conventional recycle loop.
[0049] As shown in FIGS. 3 and 4, in an aluminum smelting plant 10,
an aluminum fresh ingot 37 is manufactured from bauxite. The
aluminum purity of the aluminum fresh ingot 37 is preferably 99.7%
or more.
[0050] Next, the aluminum fresh ingot 37 is melt into molten metal
in a pre-rolling melting furnace, and then hot-rolled and
cold-rolled in an aluminum rolling mill 14. As the pre-rolling
melting furnace, a known one can be used. Thus, an aluminum sheet
16 made from 100% fresh ingots is manufactured as a roll body wound
in a coil shape. The start temperature of hot rolling is preferably
in a range of 350 to 500.degree. C. An intermediate annealing
process may be performed before, after, or in the course of hot
rolling, but, in view of inhibiting generation of CO.sub.2, the
intermediate annealing process is preferably omitted. The thickness
of the aluminum sheet obtained by rolling is preferably 0.1 to 0.4
mm. It should be noted that after rolling the flatness of the
aluminum sheet may be improved by a correction apparatus, such as a
roller leveler or a tension leveler after the rolling process.
[0051] Then, the aluminum sheet 16 that has been subjected to
rolling or the like is delivered in the state of an aluminum coil
wound in a coil shape to a lithographic printing plate
manufacturing factory 18.
[0052] In the lithographic printing plate manufacturing factory 18,
a support for a lithographic printing plate is manufactured by
performing surface-roughening process, anode oxidizing process, and
the like on the aluminum sheet 16. Next, at a step of forming a
plate forming layer, an application liquid for a photosensitive
layer is applied to a surface-roughened surface of the support for
a lithographic printing plate, and dried to form a photosensitive
layer at a drying step. Since a strip-like precursor of a
lithographic printing plate is thus manufactured, a lithographic
printing plate with inserting paper is manufactured at a processing
step by cutting the strip-like precursor laminated with strip-like
inserting paper into a rectangular sheet having predetermined
dimensions. Since scraps 33 (thin plates, approximately 1 to 60 cm
on a side) such as offcuts of the strip-like precursor, are
generated at the processing step of the strip-like precursor, they
are collected in the lithographic printing plate manufacturing
factory 18.
[0053] On the other hand, the lithographic printing plates 30
delivered to a printing company 32 are subjected to image exposure
and development, and then mounted on a printing machine for use in
printing. Then, the lithographic printing plates 36 that have been
used in printing are collected as recycled materials in the
printing company 32.
[0054] The route up to this step is the same in both the recycling
method of the present invention and the conventional recycling
method. In the recycling method of the present invention, however,
the used lithographic printing plates 36 collected in the printing
company 32, and collected printing plates 35 such as the scraps 33
collected in the lithographic printing plate manufacturing factory
18 are directly delivered to the aluminum rolling mill 14 without
passing through a recycling plant 34 (see FIG. 4), unlike the
conventional method.
[0055] Then, the collected printing plates 35 are directly melted
together with the fresh ingots 37 in the pre-rolling melting
furnace of the aluminum rolling mill 14 without making the
collected printing plates 25 as a recycled ingot, and then a
coil-shaped roll 88 of a recycled aluminum sheet is manufactured.
To such direct melting, the above-described melting method of the
present invention is applied. This makes it possible to obtain a
high melting yield even without making recycled ingots, unlike the
conventional method, and therefore the collected printing plates 35
can be recycled in one melting in the pre-rolling melting
furnace.
[0056] On the other hand, the conventional recycling method shown
in FIG. 4 has low energy efficiency since the collected printing
plates 35 must be melted twice, once in the recycling plant 34 and
once in the aluminum rolling mill 14.
[0057] Therefore, the recycling method for collected printing
plates of the present invention can remarkably improve the energy
efficiency of recycling the collected printing plates 35 as
aluminum raw material for a support for a lithographic printing
plate.
[0058] Thus, the recycling method for collected printing plates of
the present invention not only can reduce energy costs for melting,
but also can reduce transport costs since the recycling plant 34 is
not involved, and therefore a recycling system that requires lower
costs than a conventional recycling system can be established.
REFERENCE SIGNS LIST
[0059] 10: Aluminum smelting plant, 11: Melting furnace, 17:
Opening-and-closing door, 12: Aluminum fresh ingot, 13: Melting
furnace, 14: Aluminum rolling mill, 15: Slot, 16: Aluminum sheet
made from 100% fresh ingots, 17: Opening-and-closing door, 18:
Lithographic printing plate manufacturing factory, 19: Burner, 21:
Flame, 23: Piping, 25: Air-fuel ratio control device, 27: Chimney,
29: Damper, 30: Lithographic printing plate, 31: Controller, 32:
Printing company, 33: Scraps, 34: Recycling plant, 35: Collected
printing plates (used lithographic printing plates and scraps), 36:
Used lithographic printing plates, 37: Fresh ingot.
* * * * *