U.S. patent application number 16/336630 was filed with the patent office on 2020-12-10 for nickel powder manufacturing method.
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, Ryo-ma YAMAGUMA.
Application Number | 20200384542 16/336630 |
Document ID | / |
Family ID | 1000005090915 |
Filed Date | 2020-12-10 |
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United States Patent
Application |
20200384542 |
Kind Code |
A1 |
TAKAISHI; Kazuyuki ; et
al. |
December 10, 2020 |
NICKEL POWDER MANUFACTURING METHOD
Abstract
Provided is a nickel powder manufacturing method capable of
efficiently manufacturing a high-quality nickel powder using as
little ammonium gas or ammonium water as possible. The nickel
powder manufacturing method according to the present invention is
characterized by comprising: a first step for generating a
post-neutralization slurry including nickel hydroxide by mixing a
nickel sulfate aqueous solution and a neutralizing agent; a second
step for causing a complex-forming reaction by mixing an ammonium
sulfate aqueous solution with the post-neutralization slurry and
obtaining a post-complexation slurry including a nickel ammine
complex aqueous solution; and a reducing step for obtaining a
nickel powder and a post-reduction solution by contacting hydrogen
gas with the nickel ammine complex aqueous solution. Further, it is
preferable that a post-complexation solution obtained in the
reduction step be repeatedly used as the ammonium sulfate aqueous
solution to be added to the post-neutralization slurry.
Inventors: |
TAKAISHI; Kazuyuki;
(Niihama-shi, JP) ; OZAKI; Yoshitomo;
(Niihama-shi, JP) ; HEGURI; Shin-ichi;
(Niihama-shi, JP) ; YAMAGUMA; Ryo-ma;
(Niihama-shi, JP) ; DOI; Yasuo; (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: |
1000005090915 |
Appl. No.: |
16/336630 |
Filed: |
September 4, 2017 |
PCT Filed: |
September 4, 2017 |
PCT NO: |
PCT/JP2017/031757 |
371 Date: |
March 26, 2019 |
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
B22F 2301/15 20130101;
B22F 9/26 20130101 |
International
Class: |
B22F 9/26 20060101
B22F009/26 |
Foreign Application Data
Date |
Code |
Application Number |
Sep 27, 2016 |
JP |
2016-187803 |
Oct 24, 2016 |
JP |
2016-208091 |
Claims
1. A nickel powder manufacturing method, the method comprising: a
first step for generating a post-neutralization slurry containing
nickel hydroxide by mixing a nickel sulfate aqueous solution and a
neutralizing agent; a second step for causing a complex-forming
reaction by mixing an ammonium sulfate aqueous solution with the
post-neutralization slurry obtained in the first step and obtaining
a post-complexation slurry containing a nickel ammine complex
aqueous solution; and a reduction step for obtaining nickel powder
and a post-reduction solution by bringing hydrogen gas into contact
with the nickel ammine complex aqueous solution obtained in the
second step.
2. The nickel powder manufacturing method according to claim 1,
wherein in the second step, the post-reduction solution obtained in
the reduction step is used as the ammonium sulfate aqueous solution
to be mixed with the post-neutralization slurry.
3. The nickel powder manufacturing method according to claim 1, the
method further comprising a third step for subjecting the
post-complexation slurry obtained in the second step to
solid-liquid separation into a nickel ammine complex aqueous
solution and a post-complexation sediment and supplying the nickel
ammine complex aqueous solution to the reduction step.
4. The nickel powder manufacturing method according to claim 1,
wherein in the first step, slaked lime and/or sodium hydroxide is
used as the neutralizing agent.
5. The nickel powder manufacturing method according to claim 1,
wherein in the reduction step, the nickel powder is obtained by
adding ammonia water to the nickel ammine complex aqueous solution
and then bringing the hydrogen gas into contact with the nickel
ammine complex aqueous solution.
6. The nickel powder manufacturing method according to claim 2, the
method further comprising a third step for subjecting the
post-complexation slurry obtained in the second step to
solid-liquid separation into a nickel ammine complex aqueous
solution and a post-complexation sediment and supplying the nickel
ammine complex aqueous solution to the reduction step.
7. The nickel powder manufacturing method according to claim 2,
wherein in the first step, slaked lime and/or sodium hydroxide is
used as the neutralizing agent.
8. The nickel powder manufacturing method according to claim 3,
wherein in the first step, slaked lime and/or sodium hydroxide is
used as the neutralizing agent.
9. The nickel powder manufacturing method according to claim 6,
wherein in the first step, slaked lime and/or sodium hydroxide is
used as the neutralizing agent.
10. The nickel powder manufacturing method according to claim 2,
wherein in the reduction step, the nickel powder is obtained by
adding ammonia water to the nickel ammine complex aqueous solution
and then bringing the hydrogen gas into contact with the nickel
ammine complex aqueous solution.
11. The nickel powder manufacturing method according to claim 3,
wherein in the reduction step, the nickel powder is obtained by
adding ammonia water to the nickel ammine complex aqueous solution
and then bringing the hydrogen gas into contact with the nickel
ammine complex aqueous solution.
12. The nickel powder manufacturing method according to claim 4,
wherein in the reduction step, the nickel powder is obtained by
adding ammonia water to the nickel ammine complex aqueous solution
and then bringing the hydrogen gas into contact with the nickel
ammine complex aqueous solution.
13. The nickel powder manufacturing method according to claim 6,
wherein in the reduction step, the nickel powder is obtained by
adding ammonia water to the nickel ammine complex aqueous solution
and then bringing the hydrogen gas into contact with the nickel
ammine complex aqueous solution.
14. The nickel powder manufacturing method according to claim 7,
wherein in the reduction step, the nickel powder is obtained by
adding ammonia water to the nickel ammine complex aqueous solution
and then bringing the hydrogen gas into contact with the nickel
ammine complex aqueous solution.
15. The nickel powder manufacturing method according to claim 8,
wherein in the reduction step, the nickel powder is obtained by
adding ammonia water to the nickel ammine complex aqueous solution
and then bringing the hydrogen gas into contact with the nickel
ammine complex aqueous solution.
16. The nickel powder manufacturing method according to claim 9,
wherein in the reduction step, the nickel powder is obtained by
adding ammonia water to the nickel ammine complex aqueous solution
and then bringing the hydrogen gas into contact with the nickel
ammine complex aqueous solution.
Description
TECHNICAL FIELD
[0001] The present invention relates to a nickel powder
manufacturing method, and relates to a method for manufacturing
nickel powder by obtaining a nickel ammine complex aqueous solution
from nickel hydroxide and then subjecting the nickel ammine complex
aqueous solution to a hydrogen reduction treatment.
BACKGROUND ART
[0002] A nickel ammine complex aqueous solution can be used as a
useful raw material, for example, by subjecting the nickel ammine
complex aqueous solution to hydrogen reduction, fine nickel powder
can be obtained as disclosed in Patent Document 1. Such a nickel
ammine complex aqueous solution can be obtained, for example, using
ammonia gas or ammonia water in a nickel sulfate aqueous
solution.
[0003] In the method in which nickel powder is obtained by using,
as a raw material, a nickel ammine complex aqueous solution
obtained from ammonia gas or ammonia water and subjecting the
nickel ammine complex aqueous solution to hydrogen reduction,
sulfate radical generated simultaneously with the nickel powder is
bonded to ammonia to generate an ammonium sulfate aqueous solution.
Therefore, if the sulfate radical of the generated ammonium sulfate
aqueous solution is not discharged outside the system, a problem
arises in that the balance of the liquid in the reaction system is
not achieved or the sulfur grade of the nickel powder as a product
increases.
[0004] As the method of carrying out the sulfate radical outside
the system, in the related art, there is known a method of
separating and carrying out the sulfate radical as crystal powder
of ammonium sulfate using a crystallization method and newly adding
ammonia to a reaction liquid, or a method of adding a neutralizing
agent such as slaked lime or sodium hydroxide to an ammonium
sulfate aqueous solution to generate ammonia water, gypsum, and a
salt cake (sodium sulfate hydrate), discharging the sulfate radical
outside the system in the form of gypsum and a salt cake, and
recycling ammonia water in the system.
[0005] However, upon using those methods, problems arise in that
investment for facilities increases, and risk to natural
environment or working environment caused by ammonia that is a
malodorous substance increases. Further, time and effort and cost
for treating discharged water containing ammonia to be generated
are not negligible.
[0006] For this reason, a method is demanded in which a nickel
ammine complex aqueous solution is manufactured while the amount of
ammonia used is reduced as much as possible and nickel powder is
manufactured using the nickel ammine complex aqueous solution.
[0007] Patent Document 1: Japanese Unexamined Patent Application,
Publication No. 2000-063916
DISCLOSURE OF THE INVENTION
Problems to be Solved by the Invention
[0008] The present invention is proposed in view of such
circumstances, and an object thereof is to provide a nickel powder
manufacturing method by which a high-quality nickel powder can be
efficiently manufactured using as little ammonia gas or ammonia
water as possible.
Means for Solving the Problems
[0009] The present inventors have conducted intensive studies in
order to solve the aforementioned problems. As a result, they have
found that by using an ammonium sulfate aqueous solution when a
nickel ammine complex is obtained from nickel hydroxide, a
high-quality nickel powder can be efficiently obtained while the
amount of ammonia used is suppressed to the minimum, thereby
completing the present invention. Specifically, the present
invention provides the followings.
[0010] (1) A first invention of the present invention is a nickel
powder manufacturing method, the method including: a first step for
generating a post-neutralization slurry containing nickel hydroxide
by mixing a nickel sulfate aqueous solution and a neutralizing
agent; a second step for causing a complex-forming reaction by
mixing an ammonium sulfate aqueous solution with the
post-neutralization slurry obtained in the first step and obtaining
a post-complexation slurry containing a nickel ammine complex
aqueous solution; and a reduction step for obtaining nickel powder
and a post-reduction solution by bringing hydrogen gas into contact
with the nickel ammine complex aqueous solution obtained in the
second step.
[0011] (2) A second invention of the present invention is the
nickel powder manufacturing method in the first invention, in which
in the second step, the post-reduction solution obtained in the
reduction step is used as the ammonium sulfate aqueous solution to
be mixed with the post-neutralization slurry.
[0012] (3) A third invention of the present invention is the nickel
powder manufacturing method in the first or second invention, the
method further including a third step for subjecting the
post-complexation slurry obtained in the second step to
solid-liquid separation into a nickel ammine complex aqueous
solution and a post-complexation sediment and supplying the nickel
ammine complex aqueous solution to the reduction step.
[0013] (4) A fourth invention of the present invention is the
nickel powder manufacturing method in any one of the first to third
inventions, in which in the first step, slaked lime and/or sodium
hydroxide is used as the neutralizing agent.
[0014] (5) A fifth invention of the present invention is the nickel
powder manufacturing method in any one of the first to fourth
inventions, in which in the reduction step, the nickel powder is
obtained by adding ammonia water to the nickel ammine complex
aqueous solution and then bringing the hydrogen gas into contact
with the nickel ammine complex aqueous solution.
Effects of the Invention
[0015] According to the present invention, a high-quality nickel
powder can be efficiently manufactured with the amount of ammonia
used being suppressed to the minimum, and productivity can be
improved in terms of environment and cost.
BRIEF DESCRIPTION OF THE DRAWINGS
[0016] FIG. 1 is a flow diagram illustrating an example of a flow
of a nickel powder manufacturing method.
[0017] FIG. 2 is a flow diagram illustrating a flow of the nickel
powder manufacturing method when ammonia water is added in a
reduction step.
PREFERRED MODE FOR CARRYING OUT THE INVENTION
[0018] Hereinafter, a specific embodiment of the present invention
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.
[0019] The nickel powder manufacturing method according to the
present invention is a method for manufacturing nickel powder by
adding a neutralizing agent to a nickel sulfate aqueous solution to
generate nickel hydroxide, obtaining an aqueous solution of a
nickel ammine complex from the nickel hydroxide, and then
subjecting the nickel ammine complex to hydrogen reduction.
[0020] At this time, in the nickel powder manufacturing method
according to the present invention, it is characterized in that
when a nickel ammine complex is obtained from nickel hydroxide, a
complex-forming reaction of nickel is generated using an ammonium
sulfate aqueous solution.
[0021] Specifically, this nickel powder manufacturing method
includes: a first step for generating a post-neutralization slurry
containing nickel hydroxide by mixing a nickel sulfate aqueous
solution and a neutralizing agent; a second step for causing a
complex-forming reaction by mixing an ammonium sulfate aqueous
solution with the post-neutralization slurry and obtaining a
post-complexation slurry containing a nickel ammine complex aqueous
solution; and a reduction step for obtaining nickel powder and a
post-reduction solution by bringing hydrogen gas into contact with
the nickel ammine complex aqueous solution.
[0022] Further, as the ammonium sulfate aqueous solution used when
a nickel ammine complex is formed, it is preferable to use an
ammonium sulfate aqueous solution generated by subjecting the
nickel ammine complex to hydrogen reduction in the reduction step.
In this way, by repeatedly using the ammonium sulfate aqueous
solution obtained by the treatment in the reduction step in the
reaction of forming a nickel ammine complex in the second step,
nickel powder can be more efficiently manufactured.
[0023] In this way, by the nickel powder manufacturing method
according to the present invention, a high-quality nickel powder
can be manufactured while the amount of ammonium used is suppressed
to the minimum as compared to the related art. Moreover, by forming
a nickel ammine complex repeatedly using the ammonium sulfate
aqueous solution obtained in the reduction step, nickel powder can
be manufactured on the basis of the treatment that is effective in
terms of cost and industrial aspect.
[0024] Hereinafter, the nickel powder manufacturing method
according to the present invention will be described in more
detail. FIG. 1 is a flow diagram illustrating an example of a flow
of a nickel powder manufacturing method.
[0025] As illustrated in FIG. 1, the nickel powder manufacturing
method according to the present embodiment includes: a first step
for generating nickel hydroxide by adding a neutralizing agent to a
nickel sulfate aqueous solution; a second step for forming a nickel
ammine complex from the nickel hydroxide; a third step for
solid-liquid separating a nickel ammine complex aqueous solution
from the obtained slurry; and a reduction step for generating
nickel powder by subjecting the nickel ammine complex aqueous
solution to hydrogen reduction.
[First Step]
[0026] In the first step, a post-neutralization slurry containing
nickel hydroxide is generated by mixing a nickel sulfate aqueous
solution and a neutralizing agent. Incidentally, the
post-neutralization slurry is, for example, a slurry obtained by
mixing nickel hydroxide and a gypsum slurry in the case of using
slaked lime as a neutralizing agent and a slurry of nickel
hydroxide in the case of using sodium hydroxide as a neutralizing
agent.
[0027] Specifically, in the first step, a certain amount of the
nickel sulfate aqueous solution is charged, for example, in a
neutralization reaction tank and a neutralizing agent is added
thereto, so that the pH of the nickel sulfate aqueous solution is
adjusted to, for example, about 7.8 to 8.5, preferably about 8.0.
By the neutralization treatment using the neutralizing agent,
nickel hydroxide is generated from the nickel sulfate aqueous
solution and a post-neutralization slurry containing the nickel
hydroxide is obtained.
(Nickel Sulfate Aqueous Solution)
[0028] Herein, the nickel sulfate aqueous solution used in the raw
material is not particularly limited, but a sulfuric acid solution
obtained by leaching nickel can be used.
[0029] For example, it is possible to use a nickel sulfate aqueous
solution obtained by dissolving a nickel-containing material such
as an industrial intermediate consisting of one or a plurality of
mixtures selected from nickel and cobalt mixed sulfide, coarse
nickel sulfate, nickel sulfide, and the like, or scraps of nickel
metal, with sulfuric acid to obtain a nickel leachate, subjecting
the nickel leachate to a purification step such as a solvent
extraction method, an ion exchange method, or neutralization to
remove impurity elements.
[0030] Incidentally, the concentration of nickel in the nickel
sulfate aqueous solution is roughly 100 g/L to 150 g/L and is
preferably set to a value around 120 g/L, from the viewpoint that
the treatment is performed in an appropriate facility scale by
suppressing an excessively large increase in solubility or liquid
amount.
(Neutralizing Agent)
[0031] As the neutralizing agent, slaked lime (calcium hydroxide)
can be used. Incidentally, the slaked lime is preferably used in
the form of a slurry. Specifically, as the slaked lime,
commercially available products for industrial use can be used, and
there is no particular limitation. For example, commercially
available slaked lime is adjusted using water to have a slurry
concentration of about 150 g/L and used.
[0032] Incidentally, in the case of using a calcium compound as the
neutralizing agent, although not limited to slaked lime, for
example, calcium carbonate or the like can also be used.
[0033] Further, as the neutralizing agent, sodium hydroxide can
also be used. As the sodium hydroxide, commercially available
products for industrial use can be used, and there is no particular
limitation. Further, as the sodium hydroxide as the neutralizing
agent, from the viewpoint of having favorable conveying properties
and easily adjusting the added amount, the sodium hydroxide is
preferably used in the form of an aqueous solution.
[0034] Other than the sodium hydroxide, water-soluble alkali such
as potassium hydroxide, and soluble alkali such as magnesium
hydroxide or magnesium oxide may be used. These are preferable from
the viewpoint that handling is easier because, for example, time
and effort for forming a slurry can be reduced and the amount of
sediment generated is reduced.
[0035] In the first step, the reaction temperature of the
neutralization reaction is preferably set to about 40.degree. C. to
60.degree. C. and more preferably about 50.degree. C., and with
this range, thermal energy for heating in the previous or next step
is not wasteful, and the treatment can be more efficiently
performed.
[Second Step]
[0036] In the second step, a complex-forming reaction of nickel is
caused using the post-neutralization slurry containing nickel
hydroxide obtained in the first step, thereby obtaining a solution
of a nickel ammine complex. At this time, it is characterized that
an ammonium sulfate aqueous solution is used at the time of the
complex-forming reaction of nickel, and the ammonium sulfate
aqueous solution is added to the post-neutralization slurry to
obtain a solution of a nickel sulfate ammine complex as a
post-complexation slurry.
[0037] In this way, by using the ammonium sulfate aqueous solution
when a nickel ammine complex is generated, as compared to the case
of the related art where the complex-forming reaction is performed
using ammonia gas or ammonia water, facility cost and working
environment can be improved, and a high-quality nickel powder can
be efficiently manufactured.
[0038] Incidentally, the post-complexation slurry is a slurry
obtained by mixing a nickel sulfate ammine complex and a gypsum
slurry in the case of using slaked lime as a neutralizing agent in
the first step and is a slurry of a nickel sulfate ammine complex
in the case of using sodium hydroxide as a neutralizing agent.
[0039] As the ammonium sulfate aqueous solution, those having an
ammonium sulfate concentration of about 200 g/L to 500 g/L are
preferably used, and those having an ammonium sulfate concentration
of about 400 g/L are more preferably used. In the case of an
aqueous solution having an ammonium sulfate concentration of less
than 200 g/L, nickel hydroxide in the post-neutralization slurry
cannot be completely dissolved in some cases, and a double salt of
nickel may be precipitated. Further, in the case of an aqueous
solution having a concentration of more than 500 g/L, ammonium
sulfate may be precipitated beyond the solubility after the
treatment in the reduction step of the subsequent step.
[0040] The reaction temperature of the complex-forming reaction in
the second step is preferably about 40.degree. C. to 90.degree. C.
and more preferably about 60.degree. C. to 80.degree. C. When the
reaction temperature is lower than 40.degree. C., the reaction
speed is slow, which is difficult to industrially apply; on the
other hand, even when the reaction temperature is higher than
90.degree. C., the reaction speed is not changed, and the loss of
energy increases.
[0041] Herein, in the second step, when the complex-forming
reaction is caused using the ammonium sulfate aqueous solution, it
is preferable that an ammonium sulfate aqueous solution as a
post-reduction solution obtained in the reduction step described
later is recovered and repeatedly used. In this way, by repeatedly
reusing the ammonium sulfate aqueous solution obtained in the
reduction step, nickel powder can be manufactured by the treatment
that is more effective in terms of cost and industrial aspect.
[0042] Incidentally, at the time of start-up of process or in a
case where the repeatedly used amount is insufficient due to a
change in ammonia balance according to continuous operations, one
newly prepared from a separately prepared reagent or the like as
described in the related art may be complementarily used.
[Third Step]
[0043] A step for solid-liquid separating a post-complexation
slurry containing the nickel ammine complex aqueous solution
generated by the complex-forming reaction in the second step can be
provided as a third step, although this is not essential
aspect.
[0044] For example, in the case of using slaked lime as a
neutralizing agent in the first step, as described above, the
post-complexation slurry obtained in the second step is a slurry
composed of a solution having a nickel sulfate ammine complex and a
post-complexation sediment. The post-complexation sediment is a
neutralized sediment mainly containing a sulfate radical derived
from nickel sulfate as a raw material, such as gypsum based on
slaked lime as a neutralizing agent. Therefore, by providing the
step for subjecting the post-complexation slurry to a solid-liquid
separation treatment as a third step, a nickel ammine complex
aqueous solution from which the sediment is separated and removed
can be recovered, and the nickel ammine complex aqueous solution in
which such impurities are reduced can be supplied to the next step.
In this way, it can be suppressed that sulfur or the like is get
into and contained in the nickel powder generated in the reduction
step, and thus quality can be further improved.
[0045] The method for solid-liquid separation is not particularly
limited. For example, filtration under reduced pressure using a
tank filter, filtration under pressure using a filter press, and
the like are exemplified, and separation by decantation may be
performed before filtration using those filters.
[0046] Incidentally, in the case of using soluble alkali such as
sodium hydroxide or magnesium oxide as a neutralizing agent in the
first step, a neutralized sediment such as gypsum is not generated.
Therefore, the third step for the solid-liquid separation treatment
is not necessarily provided. However, since hydroxide composed of
other impurity components is generated by neutralization using
those neutralizing agents in some cases, from the viewpoint of
maintaining or improving the quality of the nickel powder generated
in the reduction step, it is preferable that the solid-liquid
separation treatment is performed to reliably supply only the
nickel ammine complex aqueous solution to the reduction step.
[Reduction Step]
[0047] In the reduction step, the hydrogen reduction is performed
by bringing hydrogen gas into contact with the obtained nickel
ammine complex aqueous solution, thereby generating nickel powder.
Specifically, first, the nickel ammine complex aqueous solution is
charged in a reaction container such as a reaction container for
high temperature and high pressure, hydrogen gas for reduction is
continuously supplied under the conditions of a predetermined
temperature and a predetermined pressure to cause hydrogen
reduction, thereby generating a slurry composed of the nickel
powder and the ammonium sulfate aqueous solution as a
post-reduction solution.
[0048] The reaction temperature in the reduction step is not
particularly limited, but is preferably about 130.degree. C. to
250.degree. C. and more preferably about 150.degree. C. to
200.degree. C. When the reaction temperature is lower than
130.degree. C., reduction efficiency may be degraded; on the other
hand, even when the reaction temperature is higher than 250.degree.
C., the reaction is not affected, and the loss of thermal energy
increases.
[0049] Further, the pressure condition inside the reaction
container at the time of the reaction is not particularly limited,
but is preferably about 1.0 MPa to 5.0 MPa and more preferably
about 2.0 MPa to 4.0 MPa. When the internal pressure is less than
1.0 MPa, reduction efficiency may be degraded; on the other hand,
even when the internal pressure is more than 5.0 MPa, the reaction
is not affected, and the loss of hydrogen gas increases.
[0050] Further, in the hydrogen reduction treatment in the
reduction step, it is preferable to add the nickel powder as seed
crystals to the nickel ammine complex aqueous solution contained in
the reaction container. By performing the hydrogen reduction
treatment in a state of the seed crystals being added in this way,
the reduction rate to the metallic nickel can be increased, and the
particle size of the nickel powder thus obtained can be
controlled.
[0051] Specifically, as the nickel powder added as seed crystals,
for example, those having an average particle size of about 0.1
.mu.m to 300 .mu.m can be used. Further, those having a particle
size of about 10 .mu.m to 200 .mu.m are more preferably used. When
the particle size of the nickel powder as seed crystals is less
than 0.1 .mu.m, the nickel powder thus obtained becomes too fine,
so that the effect of the nickel powder as seed crystals may not be
exhibited. On the other hand, when the particle size of the nickel
powder as seed crystals is more than 300 .mu.m, the nickel powder
becomes coarse, so that the nickel powder is likely to be
economically disadvantaged.
[0052] Further, as the nickel powder as seed crystals, a
commercially available nickel powder can be used, and nickel powder
chemically precipitated by a known method can be classified and
used. Furthermore, the nickel powder manufactured by the
manufacturing method may be repeatedly used. Incidentally, the
nickel powder as seed crystals may be continuously supplied to a
reaction container by using a supply device such as a slurry pump
along with the nickel ammine complex aqueous solution as a raw
material.
[0053] Further, in the hydrogen reduction treatment in the
reduction step, it is preferable to add a dispersant to the nickel
ammine complex aqueous solution. By performing the hydrogen
reduction treatment by adding a dispersant in this way, the
reduction rate to metallic nickel can be increased, and the surface
of nickel powder thus obtained can be further smoothed. Further,
aggregation or the like is prevented, and thus nickel powder having
a nearly homogeneous particle size can be manufactured.
[0054] Specifically, the dispersant is not particularly limited,
but a polymer having an anionic functional group such as sodium
polyacrylate or a polymer having a non-ionic functional group such
as polyethylene glycol or polyvinyl alcohol can be used.
[0055] Herein, in the hydrogen reduction treatment in the reduction
step, it is preferable to add ammonia water to the nickel ammine
complex aqueous solution. In this way, by adding ammonia water to
the nickel ammine complex aqueous solution and subjecting the
aqueous solution to the hydrogen reduction treatment, the reduction
rate of nickel can be increased. Specifically, FIG. 2 is a flow
diagram of a manufacturing method illustrating an aspect in which
ammonia water is added to a nickel ammine complex aqueous solution
and the nickel ammine complex aqueous solution is subjected to a
hydrogen reduction treatment.
[0056] It is known that when the nickel ammine complex aqueous
solution is subjected to the reduction treatment by using hydrogen
gas, the pH of a reduced solution (post-reduction liquid) is
gradually decreased. The present inventors have found that, due to
such a decrease in pH of the post-reduction liquid, the generated
nickel powder is dissolved again to decrease the nickel reduction
rate. From this, by adding ammonia water to the nickel ammine
complex aqueous solution and then subjecting the aqueous solution
to the hydrogen reduction treatment, a decrease in pH of the
post-reduction liquid can be suppressed, and a decrease in nickel
reduction rate, that is, a decrease in recovery amount of the
nickel powder can be suppressed.
[0057] Further, by setting the amount of ammonia water added to
small, nickel powder can be manufactured by an efficient treatment
without time and effort and cost being increased. Incidentally, it
is preferable that the amount of ammonia water added is set such
that the concentration of ammonia in the solution is, for example,
about 1 g/L to 10 g/L. When the concentration of ammonia in the
solution is less than 1 g/L, the effect of suppressing a decrease
in nickel powder recovery amount is small; on the other hand, when
the ammonia water is added at a rate exceeding 10 g/L, the loss of
the reagent is increased without the effect being improved any
more.
(Regarding Taking Out of Nickel Powder)
[0058] The reacted slurry in the reaction container which is
obtained in the reduction step is discharged, for example, to a
depressurized tank and subjected to solid-liquid separation, and
thus the nickel powder is recovered and an ammonium sulfate aqueous
solution as a post-reduction solution is taken out. The ammonium
sulfate aqueous solution taken out here is, as described above,
preferably reused as the ammonium sulfate aqueous solution for the
complex-forming reaction in the second step. Specifically, the
taken-out ammonium sulfate aqueous solution is circulated and added
to the post-neutralization slurry.
[0059] In the related art, upon recovering nickel, nickel needs to
be recovered from an unreacted nickel ammine complex aqueous
solution remaining in the ammonium sulfate aqueous solution as a
post-reduction solution. Therefore, at a stage prior to the
recovery treatment of ammonium sulfate or the treatment of
recovering ammonia water from ammonium sulfate, the treatment of
recovering nickel has to be performed, and thus a problem arises in
that facility cost or operation cost is increased. On the other
hand, by repeatedly using the total amount of the ammonium sulfate
aqueous solution generated in the reduction step as a solution for
complex-forming reaction in the second step, an operation of
preparing a separate facility to recover nickel is not necessary,
cost can be effectively reduced, and an efficient operation can be
performed.
EXAMPLES
[0060] Hereinafter, the present invention will be described in more
detail by means of Examples and Comparative Examples, but the
present invention is not limited to the following Examples.
Example 1
(First Step)
[0061] A nickel oxide ore was subjected to acid leaching under a
high temperature and a high pressure by a known method, and then
sulfuric acid was added to nickel sulfide obtained by subjecting a
nickel leachate to a sulfuration treatment while the liquid
temperature was maintained to 50.degree. C. such that the nickel
sulfide was dissolved to have a nickel concentration of 120 g/L,
thereby obtaining a nickel sulfate aqueous solution. 1 L of the
obtained nickel sulfate aqueous solution was separated, a slaked
lime slurry having a slurry concentration of 150 g/L was added
thereto, and the resultant slurry was stirred for 60 minutes and
maintained such that the pH of the slurry would be 8.0, thereby
obtaining a post-neutralization slurry. Incidentally, the final
amount of the slaked lime slurry added was 1.26 L.
(Second Step)
[0062] 1.0 L of ammonium sulfate aqueous solution having a
concentration of 1240 g/L was added to the post-neutralization
slurry containing nickel hydroxide generated in the first step.
Incidentally, the concentration of ammonium sulfate added in the
post-neutralization slurry was 400 g/L. Subsequently, stirring was
continued for 1 hour while the temperature of the aqueous solution
was maintained to 80.degree. C., and the nickel hydroxide and
ammonium sulfate in the aqueous solution was reacted with each
other to generate a nickel ammine complex. According to this, a
post-complexation slurry containing the nickel ammine complex and a
gypsum slurry was obtained.
(Third Step)
[0063] Next, the post-complexation slurry obtained in the second
step was solid-liquid separated using Nutsche and filter paper.
According to this, 2.9 L of nickel ammine complex aqueous solution
having a nickel concentration of 41 g/L was obtained as a
filtrate.
(Reduction Step)
[0064] Next, 1 L of the obtained nickel ammine complex aqueous
solution was charged in a high temperature and high pressure
reaction container, 40 g of nickel powder separately prepared as
seed crystals and sodium polyacrylate as a dispersant were added
such that the concentration would be 0.17 g/L, the temperature was
increased to 185.degree. C., and the reaction was performed for 1
hour by supplying hydrogen gas under stirring under the condition
that the internal pressure was maintained to 3.5 MPa.
[0065] After completion of the reaction, the reacted slurry was
taken out from the reaction container, the generated nickel powder
was recovered by solid-liquid separation, and the quantity thereof
was measured. As a result, it was confirmed that 90% of nickel
contained in the supplied nickel ammine complex aqueous solution
can be recovered as a metallic nickel powder.
Example 2
(First Step)
[0066] Similarly to Example 1, 1 L of nickel sulfate aqueous
solution which is dissolved under the condition of a reaction
temperature of 50.degree. C. such that the nickel concentration
would be 120 g/L was prepared. Then, 810 mL of sodium hydroxide
aqueous solution having a concentration of 200 g/L was added to the
nickel sulfate aqueous solution and mixed to obtain a
post-neutralization slurry having a pH of 8.2.
(Second Step)
[0067] To the post-neutralization slurry containing nickel
hydroxide generated in the first step, 400 g of ammonium sulfate
aqueous solution and 207 g of nickel hydroxide (in terms of Dry)
obtained in the first step and water were added so that the total
liquid amount was adjusted to 1000 mL. Subsequently, while the
temperature of the aqueous solution after the adjustment was
maintained to 80.degree. C., stirring was continued for 1 hour,
thereby generating a nickel ammine complex aqueous solution in a
state in which the total amount of nickel hydroxide and ammonium
sulfate was dissolved.
(Third Step)
[0068] In the aforementioned first step, since sodium hydroxide was
used as a neutralizing agent, sediment was not generated in the
nickel ammine complex aqueous solution discharged from the second
step. Therefore, the nickel ammine complex aqueous solution was
transferred to the reduction step without providing the third step
in which the solid-liquid separation is performed.
(Reduction Step)
[0069] Next, 1 L of the obtained nickel ammine complex aqueous
solution was charged in a high temperature and high pressure
reaction container, 40 g of nickel powder separately prepared as
seed crystals and sodium polyacrylate as a dispersant were added
such that the concentration would be 0.17 g/L, the temperature was
increased to 185.degree. C., and the reaction was performed for 1
hour by supplying hydrogen gas under stirring under the condition
that the internal pressure was maintained to 3.5 MPa.
[0070] After completion of the reaction, the reacted slurry was
taken out from the reaction container, the generated nickel powder
was recovered by solid-liquid separation, and the quantity thereof
was measured. As a result, it was confirmed that 95% of nickel
contained in the supplied nickel ammine complex aqueous solution
can be recovered as a metallic nickel powder.
Example 3
[0071] The treatment from the first step to the third step was
performed using the same method as in Example 1 to obtain 1 L of
nickel ammine complex aqueous solution.
[0072] Subsequently, 1 L of the obtained nickel ammine complex
aqueous solution was charged in a high temperature and high
pressure reaction container, and similarly to the reduction step of
Example 1, the reaction was performed for 1 hour by supplying
hydrogen gas under the conditions including a temperature of
185.degree. C. and an internal pressure of 3.5 MPa. At this time,
11.3 g of nickel powder as seed crystals and 0.5 g/L of sodium
polyacrylate as a dispersant were added to perform the reaction.
Incidentally, the pH of the post-reduction liquid was decreased to
3.8.
[0073] After completion of the reaction, the reacted slurry was
taken out from the reaction container, the generated nickel powder
was recovered by solid-liquid separation, and the quantity thereof
was measured. As a result, it was confirmed that 97.7% of nickel
contained in the supplied nickel ammine complex aqueous solution
can be recovered as a metallic nickel powder.
Example 4
[0074] The treatment from the first step to the third step was
performed using the same method as in Example 3 to obtain 1 L of
nickel ammine complex aqueous solution.
[0075] Subsequently, 15 mL of ammonia water having a concentration
of 25% was added to the obtained nickel ammine complex aqueous
solution, and the aqueous solution thereof was charged in a high
temperature and high pressure reaction container. Then, similarly
to the reduction step of Example 3, 11.3 g of nickel powder as seed
crystals and 0.5 g/L of sodium polyacrylate as a dispersant was
added and the reaction was performed for 1 hour by supplying
hydrogen gas under the conditions including a temperature of
185.degree. C. and an internal pressure of 3.5 MPa. Incidentally,
the pH of the post-reduction liquid was 7.7.
[0076] After completion of the reaction, the reacted slurry was
taken out from the reaction container, the generated nickel powder
was recovered by solid-liquid separation, and the quantity thereof
was measured. As a result, it was confirmed that 99.3% of nickel
contained in the supplied nickel ammine complex aqueous solution
can be recovered as a metallic nickel powder.
[0077] Incidentally, from the comparison with the result of Example
3, it was confirmed that the nickel reduction rate is improved by
adding a small amount of ammonia to the nickel ammine complex
aqueous solution as a target for the hydrogen reduction to suppress
a decrease in pH.
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