U.S. patent application number 15/759356 was filed with the patent office on 2018-09-13 for method for manufacturing nickel powder, and method for operating reaction facility.
This patent application is currently assigned to SUMITOMO METAL MINING CO., LTD.. The applicant listed for this patent is SUMITOMO METAL MINING CO., LTD.. Invention is credited to Yasuo Doi, Shin-Ichi Heguri, Yoshitomo Ozaki, Kazuyuki Takaishi, Ryoma Yamaguma.
Application Number | 20180257143 15/759356 |
Document ID | / |
Family ID | 58427431 |
Filed Date | 2018-09-13 |
United States Patent
Application |
20180257143 |
Kind Code |
A1 |
Doi; Yasuo ; et al. |
September 13, 2018 |
METHOD FOR MANUFACTURING NICKEL POWDER, AND METHOD FOR OPERATING
REACTION FACILITY
Abstract
A method for manufacturing nickel powder whereby a reduction in
production efficiency due to abrasion of a flash vessel connected
to a pressurized container can be suppressed when nickel powder is
generated using the pressurized container and subsequently
recovered. The method for manufacturing nickel powder comprises
charging a pressurized container with a nickel sulfate ammine
complex solution and seed crystals, adding hydrogen gas to the
pressurized container, and reducing the nickel included in the
nickel sulfate ammine complex solution, wherein, when a nickel
powder slurry obtained in the pressurized container is extracted to
a flash vessel connected to the pressurized container, the slurry
is extracted to the flash vessel while the supply rate of the
nickel ammine complex solution to the pressurized container and/or
the extraction rate of the nickel slurry from the pressurized
container is controlled so the liquid level in the pressurized
container is in a fixed range.
Inventors: |
Doi; Yasuo; (Niihama-shi,
JP) ; Takaishi; Kazuyuki; (Niihama-shi, JP) ;
Yamaguma; Ryoma; (Niihama-shi, JP) ; Ozaki;
Yoshitomo; (Niihama-shi, JP) ; Heguri; Shin-Ichi;
(Niihama-shi, JP) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
SUMITOMO METAL MINING CO., LTD. |
Tokyo |
|
JP |
|
|
Assignee: |
SUMITOMO METAL MINING CO.,
LTD.
Tokyo
JP
|
Family ID: |
58427431 |
Appl. No.: |
15/759356 |
Filed: |
July 11, 2016 |
PCT Filed: |
July 11, 2016 |
PCT NO: |
PCT/JP2016/070398 |
371 Date: |
March 12, 2018 |
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
C22B 3/06 20130101; Y02P
10/234 20151101; B22F 2999/00 20130101; C22B 23/0415 20130101; C22B
3/44 20130101; B22F 9/26 20130101; B22F 2301/15 20130101; C22B
23/0446 20130101; Y02P 10/20 20151101; B22F 9/24 20130101; B22F
2999/00 20130101; B22F 9/26 20130101; B22F 2201/013 20130101 |
International
Class: |
B22F 9/24 20060101
B22F009/24; C22B 3/00 20060101 C22B003/00; C22B 3/06 20060101
C22B003/06 |
Foreign Application Data
Date |
Code |
Application Number |
Sep 28, 2015 |
JP |
2015-190478 |
Claims
1. A method for manufacturing nickel powder, the method comprising:
charging a nickel sulfate ammine complex solution and seed crystals
in a pressurized container; adding hydrogen gas to the pressurized
container; and reducing nickel included in the nickel sulfate
ammine complex solution to manufacture nickel powder, wherein when
a slurry containing the nickel powder obtained in the pressurized
container is extracted to a flash vessel connected to the
pressurized container, the slurry is extracted to the flash vessel
while a supply rate of the nickel ammine complex solution to the
pressurized container and/or an extraction rate of the slurry from
the pressurized container is controlled so that a liquid volume in
the pressurized container is in a fixed range.
2. The method for manufacturing nickel powder according to claim 1,
wherein reduction reaction is performed in the pressurized
container by using nickel powder with a particle size of 0.1 .mu.m
to 300 .mu.m as the seed crystals and controlling a pressure in the
pressurized container to a range of 2.5 MPa to 3.5 MPa and a
temperature to a range of 150.degree. C. to 185.degree. C.
3. The method for manufacturing nickel powder according to claim 1,
wherein the nickel powder is recovered by solid-liquid separation
in the flash vessel after the slurry containing the nickel powder
reaches ordinary pressure and 100.degree. C. or lower.
4. The method for manufacturing nickel powder according to claim 1,
wherein the flash vessel has a structure in which an acid-resistant
brick is pasted to an inner surface.
5. The method for manufacturing nickel powder according to claim 1,
wherein, when the slurry containing the nickel powder is extracted
to the flash vessel, a certain amount of the slurry is caused to
remain in the flash vessel.
6. A method for operating a reaction facility used in a method for
manufacturing nickel powder, the manufacturing method including:
charging a nickel sulfate ammine complex solution and seed crystals
in a pressurized container; adding hydrogen gas to the pressurized
container; and reducing nickel included in the nickel sulfate
ammine complex solution, wherein the reaction facility includes:
the pressurized container; and a flash vessel connected to the
pressurized container, extracting a slurry containing the nickel
powder obtained in the pressurized container, and reducing the
slurry in pressure, and when the slurry is extracted from the
pressurized container to the flash vessel, the slurry is extracted
to the flash vessel while a supply rate of the nickel ammine
complex solution to the pressurized container and/or an extraction
rate of the slurry from the pressurized container is controlled so
that a liquid volume in the pressurized container is in a fixed
range.
7. The method for manufacturing nickel powder according to claim 2,
wherein the nickel powder is recovered by solid-liquid separation
in the flash vessel after the slurry containing the nickel powder
reaches ordinary pressure and 100.degree. C. or lower.
8. The method for manufacturing nickel powder according to claim 2,
wherein the flash vessel has a structure in which an acid-resistant
brick is pasted to an inner surface.
9. The method for manufacturing nickel powder according to claim 3,
wherein the flash vessel has a structure in which an acid-resistant
brick is pasted to an inner surface.
10. The method for manufacturing nickel powder according to claim
7, wherein the flash vessel has a structure in which an
acid-resistant brick is pasted to an inner surface.
11. The method for manufacturing nickel powder according to claim
2, wherein, when the slurry containing the nickel powder is
extracted to the flash vessel, a certain amount of the slurry is
caused to remain in the flash vessel.
12. The method for manufacturing nickel powder according to claim
3, wherein, when the slurry containing the nickel powder is
extracted to the flash vessel, a certain amount of the slurry is
caused to remain in the flash vessel.
13. The method for manufacturing nickel powder according to claim
4, wherein, when the slurry containing the nickel powder is
extracted to the flash vessel, a certain amount of the slurry is
caused to remain in the flash vessel.
14. The method for manufacturing nickel powder according to claim
7, wherein, when the slurry containing the nickel powder is
extracted to the flash vessel, a certain amount of the slurry is
caused to remain in the flash vessel.
15. The method for manufacturing nickel powder according to claim
8, wherein, when the slurry containing the nickel powder is
extracted to the flash vessel, a certain amount of the slurry is
caused to remain in the flash vessel.
16. The method for manufacturing nickel powder according to claim
9, wherein, when the slurry containing the nickel powder is
extracted to the flash vessel, a certain amount of the slurry is
caused to remain in the flash vessel.
17. The method for manufacturing nickel powder according to claim
10, wherein, when the slurry containing the nickel powder is
extracted to the flash vessel, a certain amount of the slurry is
caused to remain in the flash vessel.
Description
TECHNICAL FIELD
[0001] The present invention relates to a method for manufacturing
nickel powder, and more specifically, to a method for manufacturing
nickel powder by which nickel powder can be stably recovered from a
flash vessel provided at an outlet of a pressurized container in a
method for obtaining nickel powder from a nickel sulfate ammine
complex solution in the pressurized container by a reduction
treatment using hydrogen gas and a method for operating a reaction
facility at this time.
BACKGROUND ART
[0002] As a method for recovering nickel, a method for dissolving
sulfide ore or oxide ore containing nickel in a high-temperature
furnace and recovering nickel as a form of ferronickel, or a method
for obtaining a sulfide (nickel matte), then separating impurities
from a solution in which the sulfide is dissolved in an acid, and
then electrowinning the solution to obtain electric nickel has been
performed. However, these methods have a problem in that a
large-scaled facility is necessary.
[0003] Further, in recent years, it has been difficult to obtain a
relatively high-grade nickel-containing raw material suitable for
the aforementioned treatment, and a nickel recovery method
including a hydrometallurgical method in which a low grade nickel
oxide ore is acid leached under a high temperature and a high
pressure and nickel is recovered from the obtained leachate has
been used.
[0004] Furthermore, in recent years, as the industrial application
of nickel, other than stainless steel or a special alloy that has
been used previously, application of batteries, electronic
materials, or the like has been rapidly increased, and thus, for
use of these applications, a demand for readily soluble briquettes
obtained by sintering nickel powder has been increased.
[0005] In this regard, as a method for industrially manufacturing
nickel powder, which is necessary for manufacturing briquettes, by
using a hydrometallurgical process, for example, a method as
disclosed in Patent Document 1 is mentioned.
[0006] Specifically, the method disclosed in Patent Document 1 is a
method for producing nickel powder from a nickel sulfate ammine
complex solution, the method performing a treatment including: (1)
a seed crystal production step of mixing a nickel sulfate solution
and hydrazine to produce nickel powder having an average particle
size of 0.1 .mu.m to 5.0 .mu.m serving as seed crystals; (2) a seed
crystal addition step of adding the obtained nickel powder as seed
crystals to the nickel sulfate ammine complex solution to form a
mixed slurry; (3) a reduction step of blowing hydrogen gas into the
mixed slurry obtained in the seed crystal addition step to form a
reduced slurry containing nickel powder formed by precipitation of
a nickel component in the mixed slurry on the seed crystals; and
(4) a growth step of subjecting the reduced slurry obtained in the
reduction step to solid-liquid separation to separate and recover
the nickel powder as a solid phase component and then blowing
hydrogen gas into a solution prepared by adding the nickel sulfate
ammine complex solution to the recovered nickel powder to grow the
nickel powder to form high purity nickel powder. According to this
method, it is possible to easily obtain high purity nickel powder
necessary for batteries and electronic materials.
[0007] However, in a case where nickel powder is industrially
obtained by the method of Patent Document 1 described above, there
is no special problem in terms of quality, but there is a problem
in that a facility operation rate is reduced.
[0008] That is, in the aforementioned method, the treatment in the
reduction step or the growth step is performed under a high
temperature and a high pressure by charging a mixed slurry in a
pressurized container such as an autoclave; however, for example,
as described in Patent Document 2, an operation is performed in
many cases in which an ordinary pressure container called a flash
vessel is connected to the pressurized container, a
high-temperature and high-pressure slurry discharged from the
pressurized container is reduced to a degree of temperature or
pressure at which the slurry can be handled. However, abrasion of
the flash vessel is quick, and it is necessary to perform
maintenance and repair while operations are periodically stopped or
a complicated operation, for example, in which a plurality of flash
vessels are prepared and alternately used in order to avoid the
stop of the operation. Therefore, costs accordingly increase and
this causes a reduction in production efficiency.
[0009] A reduction in efficiency due to abrasion of the flash
vessel becomes a significant problem when nickel powder is obtained
using a pressurized container by a reduction treatment by hydrogen
gas. Incidentally, in the technique disclosed in Patent Document 2,
abrasion is not particularly regarded as a problem.
[0010] Patent Document 1: Japanese Unexamined Patent Application,
Publication No. 2015-140480
[0011] Patent Document 2: Japanese Unexamined Patent Application,
Publication No. 2010-59489
DISCLOSURE OF THE INVENTION
Problems to be Solved by the Invention
[0012] The present invention is proposed in view of such
circumstances, and an object thereof is to provide a method for
manufacturing nickel powder by which a reduction in production
efficiency due to abrasion of a flash vessel connected to a
pressurized container is suppressed when nickel powder is produced
using the pressurized container and then recovered.
Means for Solving the Problems
[0013] The present inventors have conducted intensive studies in
order to solve the aforementioned problems. As a result, they have
found that, when a slurry containing nickel powder produced in a
pressurized container is discharged to a flash vessel, by
maintaining a liquid volume in the pressurized container in a fixed
range, abrasion in the flash vessel can be effectively suppressed,
thereby completing the present invention.
[0014] (1) A first invention of the present invention is a method
for manufacturing nickel powder, the method including: charging a
nickel sulfate ammine complex solution and seed crystals in a
pressurized container; adding hydrogen gas to the pressurized
container; and reducing nickel included in the nickel sulfate
ammine complex solution to manufacture nickel powder, in which,
when a slurry containing the nickel powder obtained in the
pressurized container is extracted to a flash vessel connected to
the pressurized container, the slurry is extracted to the flash
vessel while a supply rate of the nickel ammine complex solution to
the pressurized container and/or an extraction rate of the slurry
from the pressurized container is controlled so that a liquid
volume in the pressurized container is in a fixed range.
[0015] (2) A second invention of the present invention is the
method for manufacturing nickel powder in the first invention, in
which reduction reaction is performed in the pressurized container
by using nickel powder with a particle size of 0.1 .mu.m to 300
.mu.m as the seed crystals and controlling a pressure in the
pressurized container to a range of 2.5 MPa to 3.5 MPa and a
temperature to a range of 150.degree. C. to 185.degree. C.
[0016] (3) A third invention of the present invention is the method
for manufacturing nickel powder in the first or second invention,
in which the nickel powder is recovered by solid-liquid separation
in the flash vessel after the slurry containing the nickel powder
reaches ordinary pressure and 100.degree. C. or lower.
[0017] (4) A fourth invention of the present invention is the
method for manufacturing nickel powder in any one of the first to
third inventions, in which the flash vessel has a structure in
which an acid-resistant brick is pasted to an inner surface.
[0018] (5) A fifth invention of the present invention is the method
for manufacturing nickel powder in any one of the first to fourth
inventions, in which, when the slurry containing the nickel powder
is extracted to the flash vessel, a certain amount of the slurry is
caused to remain in the flash vessel.
[0019] (6) A sixth invention of the present invention is a method
for operating a reaction facility used in a method for
manufacturing nickel powder, the manufacturing method including:
charging a nickel sulfate ammine complex solution and seed crystals
in a pressurized container; adding hydrogen gas to the pressurized
container; and reducing nickel included in the nickel sulfate
ammine complex solution, in which the reaction facility includes:
the pressurized container; and a flash vessel connected to the
pressurized container, extracting a slurry containing the nickel
powder obtained in the pressurized container, and reducing the
slurry in pressure, and, when the slurry is extracted from the
pressurized container to the flash vessel, the slurry is extracted
to the flash vessel while a supply rate of the nickel ammine
complex solution to the pressurized container and/or an extraction
rate of the slurry from the pressurized container is controlled so
that a liquid volume in the pressurized container is in a fixed
range.
Effects of the Invention
[0020] According to the present invention, when nickel powder is
produced using a pressurized container and then recovered, abrasion
of the inside of a flash vessel connected to the pressurized
container and extracting a slurry containing the obtained nickel
powder can be prevented, and a reduction in production efficiency
due to the abrasion of the flash vessel can be effectively
suppressed.
BRIEF DESCRIPTION OF THE DRAWINGS
[0021] FIG. 1 is a process diagram illustrating an example of the
flow of a method for manufacturing nickel powder from a nickel
sulfate ammine complex solution.
PREFERRED MODE FOR CARRYING OUT THE INVENTION
[0022] Hereinafter, a specific embodiment of the present invention
(hereinafter, referred to as "the present embodiment") will be
described in detail. Incidentally, the present invention is not
limited to the following embodiment, and various modifications can
be made within the range that does not change the spirit of the
present invention. Further, in the present specification, the
description "x to y" (x and y are arbitrary numerical values) means
"x or more and y or less" unless otherwise specified.
<<1. Outline of Method for Manufacturing Nickel
Powder>>
[0023] A method for manufacturing nickel powder according to the
present embodiment is a method for manufacturing nickel powder by
charging a nickel sulfate ammine complex solution and seed crystals
in a pressurized container and reducing nickel included in the
nickel sulfate ammine complex solution while hydrogen gas is added,
in the pressurized container.
[0024] Specifically, in this manufacturing method, for example,
reduction reaction is performed by using nickel powder with a
particle size of 0.1 .mu.m to 300 .mu.m as the seed crystals and
controlling a pressure in the pressurized container to a range of
2.5 MPa to 3.5 MPa and a temperature to a range of 150.degree. C.
to 185.degree. C., thereby obtaining nickel powder. A slurry
containing the obtained nickel powder (hereinafter, referred to as
"nickel powder slurry") is extracted to the flash vessel connected
to the pressurized container, and the high-pressure nickel powder
slurry is reduced in pressure and the temperature is decreased in
the flash vessel.
[0025] At this time, in the manufacturing method according to the
present embodiment, the slurry is extracted to the flash vessel
while a supply rate of the nickel ammine complex solution to the
pressurized container and/or an extraction rate of the nickel
powder slurry from the pressurized container is controlled so that
a liquid volume in the pressurized container is in a fixed
range.
[0026] Herein, abrasion of the flash vessel used in the
manufacturing method in which nickel is produced from the nickel
sulfate ammine complex solution by reduction by the hydrogen gas is
quick, and a treatment such as maintenance and repair while
operations are periodically stopped is necessary. Thus, production
efficiency is reduced. Such abrasion of the flash vessel is
significant even when compared with, for example, abrasion
occurring in a flash tank conventionally used in a
hydrometallurgical method for nickel oxide ore based on a high
pressure acid leaching treatment called a HPAL method. This is
caused by the fact that the nickel powder produced from the nickel
sulfate ammine complex solution by reduction reaction by hydrogen
gas is extremely hard as compared with a residue (leaching residue)
produced by the hydrometallurgical method for nickel oxide ore and,
according to this, abrasion easily occurs.
[0027] More specifically, the slurry obtained by acid leaching the
nickel oxide ore under a high temperature and a high pressure is
one obtained by precipitating a component such as iron, which is
subjected to acid dissolution once, as a form of ferric oxide or
the like, and since the slurry is a fine and soft substance like
clay, occurrence of abrasion does not almost cause a problem.
Comparing to this, the nickel powder produced from the nickel
sulfate ammine complex solution by reduction reaction using
hydrogen gas is a metal having a high hardness, also has a
non-uniform form, and is formed in a form having a convexo-concave
structure like a file. For this reason, in such a flash vessel
extracting the nickel powder, occurrence of abrasion is considered
to be significant. Further, when such high hardness nickel powder
is extracted into the flash vessel, a large impact is also applied
thereto, and thus durability of a facility is also reduced.
[0028] As a result of the studies of the present inventors, it has
been found that when the nickel powder slurry produced in the
pressurized container is extracted to the flash vessel, the liquid
level (liquid volume) in the pressurized container is maintained in
a fixed range, and thus the abrasion in the flash vessel can be
effectively suppressed.
[0029] Maintaining of the liquid volume in the pressurized
container to be constant indicates, namely, that the supply rate of
the nickel sulfate ammine complex solution to the pressurized
container and the discharged amount of the nickel powder slurry
produced in the pressurized container (the extraction rate to the
flash vessel) are controlled in a fixed range, and accordingly,
retention time is controlled in a fixed range.
[0030] When the retention time is too short, the growth of the
nickel powder in the pressurized container is not sufficient so
that a large amount of fine nickel powder is produced, and nickel
powder like an extremely fine abrasive is produced, which results
in an increase in abrasion of the flash vessel to which the nickel
powder is extracted. On the other hand, when the retention time is
extremely long, coarse nickel powder having a size larger than a
desired size is produced so that this nickel powder causes the
clogging of pipes or an impact power due to collision to the flash
vessel when the nickel powder is discharged is increased, which may
affect facility life. Further, extremely coarse nickel powder also
tends to easily precipitate in the pressurized container to cause
non-uniform nickel powder to be produced, for example, to form
further coarser nickel powder, which is not preferable.
[0031] In this regard, in the manufacturing method according to the
present embodiment, the slurry is extracted to the flash vessel
while the supply rate of the nickel sulfate ammine complex solution
to the pressurized container and/or the extraction rate of the
nickel powder slurry from the pressurized container is controlled
so that the liquid volume in the pressurized container is in a
fixed range.
[0032] In this way, by controlling the extraction rate of the
nickel powder slurry to the flash vessel so that the liquid volume
in the pressurized container is maintained in a fixed range, the
abrasion in the flash vessel can be effectively suppressed. Then,
according to this, an efficient operation can be realized and there
is no need for facility maintenance and repair and complicated
operation using a plurality of facilities, and thus a reduction in
production efficiency can be suppressed.
<<2. Regarding Method for Manufacturing Nickel Powder from
Nickel Sulfate Ammine Complex Solution>>
[0033] Hereinafter, an operation of discharging the nickel powder
slurry produced in the pressurized container to the flash vessel
will be described in detail, but prior to the description thereof,
a method for manufacturing nickel powder from a nickel sulfate
ammine complex solution by a reduction treatment using hydrogen gas
will be described.
[Regarding Each Step of Manufacturing Method]
[0034] FIG. 1 is a process diagram illustrating an example of the
flow of the manufacturing method. As illustrated in FIG. 1, the
method for manufacturing nickel powder from a nickel sulfate ammine
complex solution includes (1) a seed crystal production step of
producing seed crystals, (2) a seed crystal addition step of adding
the seed crystals to a nickel sulfate ammine complex solution, (3)
a reduction step of performing reduction by hydrogen gas, and (4) a
growth step of growing small-diameter nickel powder produced by
reduction and separating and recovering nickel powder.
(1) Seed Crystal Production Step
[0035] The seed crystal production step is, for example, to produce
fine nickel powder as seed crystals by mixing hydrazine as a
reducing agent with the high purity nickel sulfate solution with
less impurities.
[0036] Specifically, to the nickel sulfate solution, hydrazine is
added in an amount about 0.5 to 2.5 times the amount of nickel in
the solution in a molar ratio to cause the reduction reaction to
occur, thereby producing nickel powder with an average particle
size of 0.1 .mu.m to 300 .mu.m. The nickel powder is used as seed
crystals for reaction in a reduction step described below.
Incidentally, when the amount of hydrazine added is less than 0.5
time the amount of nickel in a molar ratio, nickel does not
completely react; on the other hand, even when the amount exceeds
2.5 times in a molar ratio, reaction efficiency is not affected but
the loss of chemicals increases.
[0037] Incidentally, in the seed crystal production reaction, an
alkaline compound such as ammonia may be added. In a case where
ammonia is used as the alkaline compound, regarding the amount of
ammonia added, the ammonia can be added, for example, in an amount
twice or more the amount of nickel in the nickel sulfate solution
in a molar ratio. Incidentally, at this time, the pH of the
solution is preferably adjusted to 7 to 12 by using caustic soda or
the like.
[0038] Further, a small amount of a surfactant may be added. The
particle size of the nickel powder to be produced can be reduced by
adding the surfactant into the solution and performing the
reaction.
[0039] The reaction temperature is preferably set to about
25.degree. C. to 80.degree. C. When the reaction temperature is
lower than 25.degree. C., reaction time increases, and the
industrial application of the long reaction time is not realistic.
On the other hand, when the reaction temperature exceeds 80.degree.
C., the material of a reaction tank is limited to increase the cost
of a facility.
[0040] When the nickel powder with an average particle size of 0.1
.mu.m to 300 .mu.m is produced in this way, the nickel powder is
subjected to solid-liquid separation and supplied to the next step
as a nickel powder slurry in a slurry state.
(2) Seed Crystal Addition Step
[0041] In the seed crystal addition step, the nickel powder with an
average particle size of 0.1 .mu.m to 300 .mu.m produced in the
seed crystal production step is added as seed crystals to the
nickel sulfate ammine complex solution serving as the raw material
solution in the method for manufacturing nickel powder. The seed
crystals are added in the form of the nickel powder slurry to form
a mixed slurry containing the seed crystals.
[0042] The weight of the seed crystals added at this time is not
particularly limited, but is preferably set to 1% to 100% with
respect to the weight of nickel in the nickel sulfate ammine
complex solution. When the weight of the seed crystals is less than
1% with respect to the weight of nickel, the reaction efficiency
during the reduction reaction in the next reduction step is
significantly reduced. On the other hand, when the weight of the
seed crystals exceeds 100% with respect to the weight of nickel,
the amount of the seed crystals used becomes large, which requires
much cost for producing seed crystals and is not economical.
[0043] Further, a dispersant may be added at the same time in the
seed crystal addition step. When the dispersant is added to the
nickel sulfate ammine complex solution together with the seed
crystals, the seed crystals are efficiently dispersed in the
solution, and thus the reaction efficiency in the next reduction
step can be improved. Incidentally, the dispersant is not
particularly limited, and for example, sulfonate is preferable, and
particularly, lignin sulfonate that can be industrially
inexpensively obtained is preferable.
(3) Reduction Step
[0044] In the reduction step, a nickel powder production treatment
of producing nickel powder and a solid-liquid separation treatment
of separating and recovering nickel powder from a slurry containing
the produced nickel powder are performed.
[0045] Specifically, in the nickel powder production treatment in
the reduction step, hydrogen gas is blown to the mixed slurry
obtained in the seed crystal addition step to reduce nickel in the
slurry and precipitate nickel on the seed crystals.
[0046] This nickel powder production treatment is performed in a
pressurized container such as an autoclave. Specifically, the
inside of the pressurized container is controlled under the
conditions of a pressure of 2.5 MPa to 3.5 MPa and a temperature of
150.degree. C. to 185.degree. C. to cause the reduction reaction to
occur.
[0047] Regarding the condition in the pressurized container, as
described above, the pressure condition during the reaction is set
to 2.5 MPa to 3.5 MPa. When the pressure is less than 2.5 MPa,
reduction reaction efficiency is reduced. Further, even when the
pressure exceeds 4.0 MPa, the effect of improvement in reaction
efficiency is not obtained any more; meanwhile, the loss of
hydrogen gas increases to reduce the production efficiency.
[0048] Further, as described above, the reaction temperature is set
to 150.degree. C. to 185.degree. C. When the reaction temperature
is lower than 150.degree. C., the reduction reaction efficiency is
reduced. On the other hand, even when the reaction temperature
exceeds 200.degree. C., the effect of improvement in reaction
efficiency is not obtained any more; meanwhile, the loss of thermal
energy or the like increases.
[0049] Incidentally, for example, even in a case where impurities
such as magnesium ions, sodium ions, sulfate ions, and ammonium
ions are present in the mixed slurry, since all the ions remain in
the solution, high purity nickel powder can be produced.
[0050] When the reduced slurry containing nickel powder is produced
through the nickel powder production treatment, the solid-liquid
separation treatment is then performed, and high purity nickel
powder is separated and recovered from the reduced slurry.
Incidentally, the solid-liquid separation treatment can be
performed by a general method, and for example, can be performed by
using a solid-liquid separation device such as a thickener.
Further, when the solid-liquid separation is performed, the
solid-liquid separation is preferably performed while the nickel
powder slurry is in a state of ordinary pressure and 100.degree. C.
or lower, and such pressure-reducing and temperature-lowering
treatments are performed in a flash vessel connected to a
pressurized container.
(4) Growth Step
[0051] In the growth step, the nickel sulfate ammine complex
solution is further added to the high purity nickel powder obtained
in the reduction step and hydrogen gas is supplied thereto, and
nickel is reduced and precipitated on the high purity nickel powder
to grow particles.
[0052] Specifically, in the growth step, as described above, a
particle growth treatment of reducing and precipitating nickel on
the high purity nickel powder to grow particles and a solid-liquid
separation treatment of recovering the obtained nickel powder by
solid-liquid separation are performed.
[0053] The particle growth treatment in the growth step can be
performed by using a pressurized container similarly to the nickel
powder production treatment in the reduction step, and can be
performed under the treatment condition similar to that in the
reduction step described above. Further, the solid-liquid
separation treatment of separating and recovering the obtained
nickel powder can be also performed by a general method using a
thickener or the like.
[0054] High purity nickel powder having a higher bulk density and a
higher particle size can be produced by repeatedly performing such
treatments in the growth step a plurality of times.
[Regarding Productization of Nickel Powder]
[0055] The nickel powder obtained by the aforementioned
manufacturing method can be productized, for example, by subjecting
the nickel powder to a nickel powder briquetting treatment and a
briquette calcination treatment to form the nickel powder in a
briquette form that is coarser and difficult to oxidize and easy to
handle.
(Nickel Powder Briquetting Treatment)
[0056] As a product form of high purity nickel powder, a nickel
briquette form is mentioned. In order to obtain a nickel briquette,
first, the nickel powder after being dried is processed for shaping
with a briquetting machine or the like to obtain nickel briquettes
in a block form. Further, at this time, in order to improve the
processability to form the briquettes, a material that does not
impair the product quality such as water can be added as a binder
to the nickel powder.
(Briquette Sintering Treatment)
[0057] The nickel briquettes prepared in the aforementioned
briquetting treatment are subjected to roasting and sintering in a
hydrogen atmosphere to prepare a briquette sintered compact. This
treatment is performed for increasing the strength of the
briquettes and removing ammonia and a sulfur component remaining in
a trace amount. The temperature in the roasting and sintering is,
for example, preferably set to 500.degree. C. to 1200.degree. C.
When the temperature is lower than 500.degree. C., the sintering is
not sufficient; on the other hand, even when the temperature
exceeds 1200.degree. C., the efficiency hardly changes but the loss
of energy increases.
<<3. Extraction of Nickel Powder Slurry to Flash
Vessel>>
[0058] As described above, in the method for manufacturing nickel
powder from a nickel sulfate ammine complex solution, at least in
the nickel powder production treatment in the reduction step and
the particle growth treatment in the growth step, production
reaction of nickel powder is caused to occur using a reaction
facility provided with a pressurized container such as an autoclave
and a flash vessel connected to the pressurized container.
[0059] In the pressurized container such as an autoclave, under the
high-temperature and high-pressure condition of a pressure of 2.5
MPa to 3.5 MPa and a temperature of 150.degree. C. to 185.degree.
C., hydrogen gas is added to the slurry containing the nickel
sulfate ammine complex solution, and nickel in the solution is
reduced to produce nickel powder. According to this nickel powder
production reaction, a nickel powder slurry is produced in the
pressurized container.
[0060] The state of the nickel powder slurry produced in the
pressurized container is maintained to be a high-temperature and
high-pressure state. Therefore, the nickel powder slurry is
extracted from the pressurized container to the flash vessel, a
pressure-reducing treatment is performed on the nickel powder
slurry in the flash vessel to have a pressure state of ordinary
pressure. Further, at the same time, in the flash vessel, the
high-temperature nickel powder slurry is naturally cooled to be a
nickel powder slurry set to, for example, a temperature of
100.degree. C. or lower.
[0061] At this time, in the present embodiment, when the nickel
powder slurry is extracted from the pressurized container to the
flash vessel, the nickel powder slurry is extracted while the
supply rate of the nickel ammine complex solution to the
pressurized container and/or the amount of the nickel powder slurry
discharged from the pressurized container is controlled so that a
liquid volume in the pressurized container is in a fixed range.
[0062] Herein, the method for controlling the liquid volume in the
pressurized container is not particularly limited, but for example,
the liquid volume can be controlled by installing a valve, a
metering pump, or the like in a supply pipe for the nickel sulfate
ammine complex solution to be supplied to the pressurized
container, and then performing adjustment of opening/closing
(ON/OFF) and opening degree of the valve, adjustment of the flow
rate by the metering pump, and the like. Further, extraction of the
nickel powder slurry to the flash vessel may be controlled by
installing a valve, a metering pump, or the like in a discharge
pipe for connecting the pressurized container and the flash vessel
and discharging the nickel powder slurry, and similarly, performing
adjustment of opening/closing and opening degree of the valve and
adjustment of the flow rate by the metering pump.
[0063] Incidentally, the liquid volume in the pressurized
container, that is, the liquid volume that is maintained in a fixed
range is not particularly limited. It is preferable to
appropriately adjust the liquid volume depending on the size of the
device, a desired amount of production, or the like.
[0064] In this way, by controlling the amount discharged to the
flash vessel so that the liquid volume in the pressurized container
is maintained in a fixed range, the abrasion in the flash vessel
can be effectively suppressed. Then, according to this, an
efficient operation can be realized, there is no need for facility
maintenance and repair and complicated operation using a plurality
of facilities, a reduction in production efficiency can be
suppressed.
[0065] Further, as the flash vessel, a flash vessel may have a
structure in which an acid-resistant brick is pasted to the inner
surface thereof. By lining the brick to the inner surface of the
flash vessel in this way, abrasion can be suppressed more
effectively.
[0066] Further, when the nickel powder slurry is extracted from the
pressurized container to the flash vessel, in a state where a
certain amount of the nickel powder slurry remains in the flash
vessel, it is preferable to sequentially extract the nickel powder
slurry from the pressurized container to the flash vessel in this
state. As described above, when a certain amount of the nickel
powder slurry remains at all times without the total amount of the
nickel powder slurry in the flash vessel being discharged and the
inside of the flash vessel being made empty, an impact of the
nickel powder slurry to be subsequently discharged to the inside of
the flash vessel can be alleviated, abrasion can be suppressed more
effectively, and durability can be improved.
[0067] When the nickel powder slurry is extracted to the inside of
the flash vessel while the extraction rate of the nickel powder
slurry is controlled so that the liquid volume in the pressurized
container is maintained in a fixed range in this way, the
pressure-reducing treatment or the temperature-lowering treatment
is performed on the nickel powder slurry in the flash vessel.
Specifically, in the flash vessel, the nickel powder slurry is set
to be in a state of a pressure of ordinary pressure and a state a
temperature of 100.degree. C. or lower. Further, after the nickel
powder slurry is in a state of ordinary pressure and 100.degree. C.
or lower, the nickel powder slurry is transferred from the flash
vessel to a solid-liquid separation device such as a thickener and
then subjected to the solid-liquid separation treatment of
separating and recovering the nickel powder. In the manufacturing
method according to the present embodiment, since the abrasion of
the flash vessel can be effectively suppressed, the
pressure-reducing treatment or the temperature-lowering treatment
is appropriately carried out in the flash vessel, and thus the
nickel powder can be efficiently recovered.
EXAMPLES Hereinafter, the present invention will be described in
more detail by means of Operation Examples, but the present
invention is not limited to the following Examples at all.
Operation Example 1
[0068] In a pressurized container with an inner capacity of 190 L
equipped with a stirrer, 90 L of a solution containing 362 g/L of
ammonium sulfate and 100 g/L of nickel powder with a particle size
of 10 .mu.m was charged. Then, the temperature of the pressurized
container was increased to 185.degree. C. and maintained, and then
hydrogen gas was supplied from a cylinder so that the internal
pressure of the pressurized container was maintained to 2.5
MPa.
[0069] Subsequently, a solution (reaction starting solution)
containing a nickel sulfate ammine complex solution (75 g/L as a
nickel component) and 330 g/L of ammonium sulfate was supplied to
the pressurized container at a flow rate of 1 L/min using a
metering pump, and 150 g/L of nickel powder slurry was further
added quantitatively at a flow rate of 0.5 L/min. Incidentally, at
this time, the hydrogen gas was blown from the cylinder so that the
pressure in the pressurized container was maintained to a range of
2.5 MPa to 3.5 MPa.
[0070] Regarding the liquid in the pressurized container, while the
liquid volume was controlled by a timer so that the liquid volume
in the container was maintained to a range of 90.+-.5 L, the supply
rate of the reaction starting solution to the pressurized container
and the amount of the nickel powder slurry discharged from the
pressurized container were managed by operation of a valve, and
then the obtained nickel powder slurry was extracted to a flash
vessel. In the flash vessel, the accommodated nickel powder slurry
was reduced in pressure to ordinary pressure and cooled. After
completion of the operation for 45 minutes, the nickel powder
slurry was recovered from the bottom outlet of the flash vessel.
The temperature of the recovered nickel powder slurry was
56.degree. C.
[0071] Incidentally, before the treatment, air in the flash vessel
was replaced with nitrogen by blowing nitrogen gas in advance into
the flash vessel. Further, in the flash vessel, as an abrasion
resistance countermeasure, a structure in which an acid-resistant
brick was pasted to an inner surface of the flash vessel was
employed. Furthermore, in a connection portion of the flash vessel
with the pressurized container, a flow rate adjustment valve called
a flash valve or a let-down valve was installed, and a nozzle
called a blast tube (or a blast spool) which alleviates an impact
when the nickel powder slurry is discharged to the flash vessel was
installed from the valve toward the inside of the flash vessel main
body.
[0072] Further, during the operation, the level of the nickel
powder slurry in the flash vessel was maintained to be constant,
and thus the impact due to the discharging of the nickel powder
slurry from the pressurized container was alleviated. Incidentally,
the level of the slurry in the flash vessel may be a depth enough
to alleviate the impact of the nickel powder slurry, and the level
thereof was appropriately determined while the operation was
performed. The nickel powder slurry was recovered from the bottom
outlet of the flash vessel.
[0073] According to such an operation, the amount of the nickel
powder slurry recovered in the flash vessel was 65.5 L in total by
the operation for 45 minutes, and the concentration of the nickel
powder slurry was 53 g/L.
Operation Example 2
[0074] The operation was performed continuously for 96 hours using
the same facility and operation condition as those in Operation
Example 1 described above.
[0075] After completion of the operation, when the inside of the
flash vessel was visually observed using a magnifying glass,
abrasion or damage of the flash vessel main body was not confirmed
at all.
Comparative Operation Example 1
[0076] The operation was performed using the facility and liquid
condition similar to those in Operation Example 1 described above;
however, the liquid was extracted from the inside of the
pressurized container every time the operation was performed, and
the liquid level in the pressurized container changed in a range of
20 L to 130 L and was not maintained to be constant. Such an
operation was performed continuously for 96 hours.
[0077] After completion of the operation, when the inside of the
flash vessel was visually observed using a magnifying glass, a
large number of impact traces or scratches were confirmed and the
facility was in a state in which maintenance and repair are
necessary sooner or later.
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