U.S. patent application number 16/954357 was filed with the patent office on 2020-12-03 for method for producing nickel powder.
The applicant listed for this patent is SUMITOMO METAL MINING CO., LTD.. Invention is credited to Shin-ichi Heguri, Kazuyuki Takaishi.
Application Number | 20200376564 16/954357 |
Document ID | / |
Family ID | 1000005032619 |
Filed Date | 2020-12-03 |
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United States Patent
Application |
20200376564 |
Kind Code |
A1 |
Heguri; Shin-ichi ; et
al. |
December 3, 2020 |
METHOD FOR PRODUCING NICKEL POWDER
Abstract
Provided is a method for manufacturing coarse particles of a
so-called high-purity nickel powder with a small amount of
impurities, particularly having a low sulfur grade, from a nickel
sulfate amine complex solution using a fine nickel powder. A method
for manufacturing a nickel powder includes the following treatment
steps (1) to (6) in a process for manufacturing a nickel powder
from a nickel sulfate solution: (1) a hydroxylation step; (2) a
complexation step; (3) a reduction step; (4) a solid/liquid
separation step; (5) a nickel recovery step of repeatedly supplying
the recovered nickel powder to step (2) and/or step (3),
sulfurating the recovered final reduction solution, and then
solid/liquid separating the sulfurated solution to generate nickel
sulfide and a nickel post-reduction solution; and (6) a nickel
regeneration step of oxidatively leaching the nickel sulfide
obtained in step (5) and repeatedly supplying the obtained nickel
sulfate solution to step (1).
Inventors: |
Heguri; Shin-ichi;
(Niihama-shi, JP) ; Takaishi; Kazuyuki;
(Niihama-shi, JP) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
SUMITOMO METAL MINING CO., LTD. |
Tokyo |
|
JP |
|
|
Family ID: |
1000005032619 |
Appl. No.: |
16/954357 |
Filed: |
November 22, 2018 |
PCT Filed: |
November 22, 2018 |
PCT NO: |
PCT/JP2018/043216 |
371 Date: |
June 16, 2020 |
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
C22B 3/08 20130101; C22B
23/0407 20130101; C22B 3/14 20130101; B22F 3/16 20130101; B22F
2301/15 20130101; B22F 9/26 20130101 |
International
Class: |
B22F 9/26 20060101
B22F009/26; C22B 3/00 20060101 C22B003/00; C22B 3/14 20060101
C22B003/14; C22B 3/08 20060101 C22B003/08; B22F 3/16 20060101
B22F003/16 |
Foreign Application Data
Date |
Code |
Application Number |
Dec 21, 2017 |
JP |
2017-245631 |
Claims
1. A method for manufacturing a nickel powder from a nickel sulfate
solution, comprising: (1) a hydroxylation step of adding an alkali
to the nickel sulfate solution to generate a precipitate of nickel
hydroxide; (2) A complexation step of adding a final reduction
solution obtained from a solid/liquid separation step (4) and a
nickel powder as a seed crystal to the precipitate of nickel
hydroxide generated in the hydroxylation step (1), and dissolving
the precipitate of the nickel hydroxide to form a mixed slurry
containing a nickel sulfate amine complex solution, the seed
crystal, and the nickel hydroxide; (3) a reduction step of blowing
a hydrogen gas into the mixed slurry formed in the complexation
step (2) to form a reduced slurry containing a nickel powder formed
by precipitation of a nickel component in the mixed slurry on the
seed crystal; (4) a solid/liquid separation step of solid/liquid
separating the reduced slurry formed in the reduction step (3) and
recovering a nickel powder and a final reduction solution; (5) a
nickel recovery step of repeatedly supplying the recovered nickel
powder to either or both of the complexation step (2) and the
reduction step (3), adding a sulfurizing agent to the recovered
final reduction solution, precipitating nickel sulfide, and
subjecting it to solid/liquid separation to generate nickel sulfide
and a nickel post-reduction solution; and (6) a nickel regeneration
step of oxidatively leaching the nickel sulfide obtained in the
nickel recovery step (5) and repeatedly supplying the obtained
nickel sulfate solution to the hydroxylation step (1).
2. The method for manufacturing a nickel powder according to claim
1, wherein sieving the nickel powder recovered in the solid/liquid
separation step (4) according to a particle size, selecting a
nickel powder having a smaller size than a predetermined particle
size, and adding the selected nickel powder to the complexation
step (2) and/or the reduction step (3) as a seed crystal are
repeatedly performed to obtain a nickel powder having a larger
particle size than the nickel powder as the seed crystal.
3. The method for manufacturing a nickel powder according to claim
2, wherein the seed crystal added in either or both of the
complexation step (2) and the reduction step (3) has an average
particle size of 0.1 to 100 .mu.m.
4. The method for manufacturing a nickel powder according to claim
1, wherein when the mixed slurry containing a nickel sulfate amine
complex solution, a seed crystal, and nickel hydroxide is formed in
the complexation step (2), a dispersant is further added to the
mixed slurry.
5. The method for manufacturing a nickel powder according to claim
1, wherein the seed crystal is added in an amount of 1 to 100% with
respect to a weight of nickel in the nickel sulfate amine complex
solution in the complexation step (2).
6. The method for manufacturing a nickel powder according to claim
1, wherein the reduced slurry is sieved, and the sieved nickel
powder and the sieved reduced slurry as a final reduction solution
are repeatedly used as a part of the final reduction solution and
the nickel powder as a seed crystal in the complexation step
(2).
7. The method for manufacturing a nickel powder according to claim
6, wherein the complexation step (2) includes two steps of a
dissolving step of adding a final reduction solution to obtain a
nickel sulfate amine complex solution, and a seed crystal adding
step of adding a nickel powder or a mixed slurry containing a
nickel powder and a final reduction solution.
8. The method for manufacturing a nickel powder according to claim
1, wherein the nickel sulfate solution is obtained by dissolving at
least one selected from a mixed sulfide of nickel and cobalt
recovered by leaching nickel oxide ore, nickel sulfide, crude
nickel sulfate, nickel oxide, nickel hydroxide, nickel carbonate,
and a nickel metal powder, in a sulfuric acid acidic solution.
9. The method for manufacturing a nickel powder according to claim
1, wherein the nickel sulfate solution is obtained through a
leaching step of dissolving a nickel-containing material containing
cobalt as impurities, and a solvent extraction step of adjusting a
pH of a leachate containing nickel and cobalt obtained in the
leaching step and then separating the leachate into a nickel
sulfate solution and a cobalt recovery solution by a solvent
extraction method.
10. The method for manufacturing a nickel powder according to claim
1, wherein an ammonium sulfate concentration in the nickel sulfate
amine complex solution is 100 to 500 g/L, and an ammonium
concentration is 1.9 or more in a molar ratio with respect to a
nickel concentration in the complex solution.
11. The method for manufacturing a nickel powder according to claim
1, wherein blowing of a hydrogen gas performed while a temperature
is maintained in a range of 100 to 200.degree. C. and a pressure is
maintained in a range of 0.8 to 4.0 MPa in the reduction step
(3).
12. The method for manufacturing a nickel powder according to claim
4, wherein the dispersant contains a polyacrylate.
13. The method for manufacturing a nickel powder according to claim
1, further comprising: a nickel powder briquetting step of
processing the nickel powder obtained through the reduction step
(3) into a massive nickel briquette using a briquetting machine;
and a briquette sintering step of sintering the obtained massive
nickel briquette in a hydrogen atmosphere under a holding condition
of a temperature of 500 to 1200.degree. C. to form a nickel
briquette as a sintered body.
14. The method for manufacturing a nickel powder according to claim
1, further comprising an ammonium sulfate recovery step of
concentrating the final reduction solution in the solid/liquid
separation step (4), crystallizing ammonium sulfate, and recovering
an ammonium sulfate crystal.
15. The method for manufacturing a nickel powder according to claim
1, further comprising an ammonia recovery step of adding an alkali
to the final reduction solution in the solid/liquid separation step
(4), heating the resulting mixture, volatilizing an ammonia gas,
and recovering ammonia.
Description
TECHNICAL FIELD
[0001] The present invention relates to a method for obtaining a
high-purity nickel powder having a low sulfur grade from a nickel
sulfate amine complex solution and a briquette obtained by
solidifying the nickel powder.
[0002] In particular, the present invention can be applied to a
treatment of an intermediate generating solution generated in a
step in a nickel hydrometallurgical process.
BACKGROUND ART
[0003] As a method for industrially manufacturing a nickel powder
using a hydrometallurgical process, there is a method for
manufacturing a nickel powder by dissolving a raw material in a
sulfuric acid solution, then removing impurities, adding ammonia to
the obtained nickel sulfate solution to form a nickel amine
complex, and supplying a hydrogen gas to the generated nickel
sulfate amine complex solution to reduce the nickel.
[0004] For example, Non Patent Literature 1 describes a nickel
powder manufacturing process for adding an iron compound as a seed
crystal during a reduction reaction and precipitating nickel on the
iron compound. However, this method has a disadvantage that iron
derived from the seed crystal is mixed into a product.
[0005] Furthermore, a method for obtaining a nickel powder using a
reducing agent other than a hydrogen gas has been proposed so
far.
[0006] For example, Patent Literature 1 discloses a method for
providing a nickel powder that is inexpensive, has excellent
weather resistance, has a low electric resistance in a state of
being kneaded with a resin, reduces an initial electric resistance
and an electric resistance during use, can be used stably for a
long time, and is suitable as a conductive particle for a
conductive paste and a conductive resin, and a method for
manufacturing the nickel powder.
[0007] The nickel powder disclosed in Patent Literature 1 contains
1 to 20% by mass of cobalt and the balance composed of nickel and
unavoidable impurities, is formed of secondary particles obtained
by aggregating primary particles, and contains 0.8% by mass or less
of oxygen. It is stated that cobalt is preferably contained only in
a surface layer of the secondary particles, and the cobalt content
in the surface layer is preferably 1 to 40% by mass. When this
nickel powder is to be obtained by the disclosed manufacturing
method, cobalt coexists. This method is not suitable, for example,
for an application to separate nickel and cobalt from each other
when nickel and cobalt coexist as in nickel oxide ore, and to
recover nickel and cobalt with high purity and economically.
[0008] Furthermore, Patent Literature 2 provides a method for
manufacturing a metal powder by a liquid phase reduction method.
This method has been improved such that particle aggregates are not
easily generated.
[0009] This manufacturing method includes: a first step of
preparing an aqueous solution containing metal ions derived from a
metal compound by dissolving the metal compound, a reducing agent,
a complexing agent, and a dispersant; and a second step of reducing
the metal ions with the reducing agent by adjusting the pH of the
aqueous solution to precipitate a metal powder.
[0010] However, this manufacturing method is expensive due to use
of expensive chemicals, and is not economically advantageous when
being applied to a large-scale process as the above nickel
hydrometallurgy.
[0011] As described above, various processes for manufacturing a
nickel powder have been proposed. However, a method for
manufacturing a high-purity nickel powder using an industrially
inexpensive hydrogen gas has not been proposed.
CITATION LIST
Patent Literature
[0012] Patent Literature 1: JP 2005-240164 A [0013] Patent
Literature 2: JP 2010-242143 A
Non Patent Literature
[0013] [0014] Non Patent Literature 1: POWDER METALLURGY, 1958, No.
1/2, p. 40-52.
SUMMARY OF INVENTION
Technical Problem
[0015] Under such circumstances, an object is to provide a method
for manufacturing, using an industrially inexpensive hydrogen gas,
coarse particles of a so-called high-purity nickel powder,
containing a small amount of impurities and particularly having a
low sulfur grade, from a nickel sulfate amine complex solution
using a fine nickel powder.
Solution to Problem
[0016] A first aspect of the present invention for solving the
above problems provides a method for manufacturing a nickel powder
from a nickel sulfate solution, including:
[0017] (1) a hydroxylation step of adding an alkali to the nickel
sulfate solution to generate a precipitate of nickel hydroxide;
[0018] (2) a complexation step of adding a final reduction solution
obtained from a solid/liquid separation step (4) and a nickel
powder as a seed crystal to the precipitate of nickel hydroxide
generated in the hydroxylation step (1), and dissolving the
precipitate of the nickel hydroxide to form a mixed slurry
containing a nickel sulfate amine complex solution, the seed
crystal, and the nickel hydroxide;
[0019] (3) a reduction step of blowing a hydrogen gas into the
mixed slurry formed in the complexation step (2) to form a reduced
slurry containing a nickel powder formed by precipitation of a
nickel component in the mixed slurry on the seed crystal;
[0020] (4) a solid/liquid separation step of solid/liquid
separating the reduced slurry formed in the reduction step (3) and
recovering a nickel powder and a final reduction solution;
[0021] (5) a nickel recovery step of repeatedly supplying the
recovered nickel powder to either or both of the complexation step
(2) and the reduction step (3), adding a sulfurizing agent to the
recovered final reduction solution, precipitating nickel sulfide,
and subjecting it to solid/liquid separation to generate nickel
sulfide and a nickel post-reduction solution; and
[0022] (6) a nickel regeneration step of oxidatively leaching the
nickel sulfide obtained in the nickel recovery step (5) and
repeatedly supplying the obtained nickel sulfate solution to the
hydroxylation step (1).
[0023] A second aspect of the present invention provides a method
for manufacturing a nickel powder, in which sieving the nickel
powder recovered in the solid/liquid separation step (4) in the
first aspect of the present invention according to a particle size,
selecting a nickel powder having a smaller size than a
predetermined particle size, and adding the selected nickel powder
to either or both of the complexation step (2) and the reduction
step (3) as a seed crystal are repeatedly performed to obtain a
nickel powder having a larger particle size than the nickel powder
as the seed crystal.
[0024] A third aspect of the present invention provides a method
for manufacturing a nickel powder, in which the seed crystal added
in either or both of the complexation step (2) and the reduction
step (3) in the second aspect of the present invention has an
average particle size of 0.1 to 100 .mu.m.
[0025] A fourth aspect of the present invention provides a method
for manufacturing a nickel powder, in which when the mixed slurry
containing a nickel sulfate amine complex solution, a seed crystal,
and nickel hydroxide is formed in the complexation step (2) in the
first to third aspects of the present invention, a dispersant is
further added to the mixed slurry.
[0026] A fifth aspect of the present invention provides a method
for manufacturing a nickel powder, in which the seed crystal is
added in an amount of 1 to 100% with respect to the weight of
nickel in the nickel sulfate amine complex solution in the
complexation step (2) in the first to fourth aspects of the present
invention.
[0027] A sixth aspect of the present invention provides a method
for manufacturing a nickel powder, in which the reduced slurry in
the first to fifth aspects of the present invention is sieved, and
the sieved nickel powder and the sieved reduced slurry as a final
reduction solution are repeatedly used as a part of the final
reduction solution and the nickel powder as a seed crystal in the
complexation step (2).
[0028] A seventh aspect of the present invention provides a method
for manufacturing a nickel powder, in which the complexation step
(2) in the sixth aspect of the present invention includes two steps
of a dissolving step of adding a final reduction solution to obtain
a nickel sulfate amine complex solution, and a seed crystal adding
step of adding a nickel powder or a mixed slurry containing a
nickel powder and a final reduction solution.
[0029] An eighth aspect of the present invention provides a method
for manufacturing a nickel powder, in which the nickel sulfate
solution in the first aspect of the present invention is obtained
by dissolving at least one selected from a mixed sulfide of nickel
and cobalt recovered by leaching nickel oxide ore, nickel sulfide,
crude nickel sulfate, nickel oxide, nickel hydroxide, nickel
carbonate, and a nickel metal powder, in a sulfuric acid acidic
solution.
[0030] A ninth aspect of the present invention provides a method
for manufacturing a nickel powder, in which the nickel sulfate
solution in the first aspect of the present invention is obtained
through a leaching step of dissolving a nickel-containing material
containing cobalt as impurities, and a solvent extraction step of
adjusting the pH of a leachate containing nickel and cobalt
obtained in the leaching step and then separating the leachate into
a nickel sulfate solution and a cobalt recovery solution by a
solvent extraction method.
[0031] A tenth aspect of the present invention provides a method
for manufacturing a nickel powder, in which the ammonium sulfate
concentration in the nickel sulfate amine complex solution in the
first aspect of the present invention is 100 to 500 g/L, and the
ammonium concentration is 1.9 or more in a molar ratio with respect
to the nickel concentration in the complex solution.
[0032] An eleventh aspect of the present invention provides a
method for manufacturing a nickel powder, in which blowing of a
hydrogen gas is performed, while the temperature is maintained in a
range of 100 to 200.degree. C. and the pressure is maintained in a
range of 0.8 to 4.0 MPa in the reduction step (3) in the first
aspect of the present invention.
[0033] A twelfth aspect of the present invention provides a method
for manufacturing a nickel powder, in which the dispersant in the
fourth aspect of the present invention contains a polyacrylate.
[0034] A thirteenth aspect of the present invention provides a
method for manufacturing a nickel powder, further including: a
nickel powder briquetting step of processing the nickel powder
obtained through the reduction step (3) in the first aspect of the
present invention into a massive nickel briquette using a
briquetting machine; and a briquette sintering step of sintering
the obtained massive nickel briquette in a hydrogen atmosphere
under a holding condition of a temperature of 500 to 1200.degree.
C. to form a nickel briquette as a sintered body.
[0035] A fourteenth aspect of the present invention provides a
method for manufacturing a nickel powder, further including an
ammonium sulfate recovery step of concentrating the final reduction
solution in the solid/liquid separation step (4) in the first
aspect of the present invention, crystallizing ammonium sulfate,
and recovering an ammonium sulfate crystal.
[0036] A fifteenth aspect of the present invention provides a
method for manufacturing a nickel powder, further including an
ammonia recovery step of adding an alkali to the final reduction
solution in the solid/liquid separation step (4) in the first
aspect of the present invention, heating the resulting mixture,
volatilizing an ammonia gas, and recovering ammonia.
Advantageous Effects of Invention
[0037] The present invention provides a method for manufacturing a
nickel powder from a nickel sulfate amine complex solution using a
hydrogen gas, in which a high-purity nickel powder with a small
amount of impurities can be easily obtained, and an industrially
remarkable effect is exhibited.
BRIEF DESCRIPTION OF DRAWINGS
[0038] FIG. 1 is a flowchart for manufacturing a nickel powder
according to the present invention.
DESCRIPTION OF EMBODIMENTS
[0039] The present invention provides a method for manufacturing a
nickel powder from a nickel sulfate amine complex solution, in
which by subjecting a process liquid in a hydrometallurgical
process to the following steps (1) to (6), a high-purity nickel
powder with a smaller amount of impurities is manufactured from a
nickel amine sulfate complex solution.
[0040] Hereinafter, the method for manufacturing a high-purity
nickel powder according to the present invention will be described
with reference to the flowchart for manufacturing a high-purity
nickel powder according to the present invention illustrated in
FIG. 1.
[0041] [Leaching Step]
[0042] First, a leaching step is for dissolving, with a sulfuric
acid, one selected from the group consisting of a mixed sulfide of
nickel and cobalt, crude nickel sulfate, nickel oxide, nickel
hydroxide, nickel carbonate, a nickel powder, and the like which
are starting raw materials, or a nickel-containing material such as
an industrial intermediate containing a mixture of a plurality of
substances, and for leaching nickel to generate a leachate (a
sulfuric acid solution containing nickel). This leaching step is
performed by a known method disclosed in JP 2005-350766 A or the
like.
[0043] [Solvent Extraction Step]
[0044] Next, the pH of the leachate is adjusted, and the leachate
is subjected to a solvent extraction step.
[0045] In this step, the leachate adjusted in pH after being
obtained in the leaching step is brought into contact with an
organic phase, and the components in the phases are exchanged to
increase the concentration of a certain component in the aqueous
phase and to decrease the concentration of another component.
[0046] In the present invention, by using 2-ethylhexylphosphonic
acid mono-2-ethylhexyl ester or di-(2,4,4-trimethylpentyl)
phosphinic acid as the organic phase, an impurity element in the
leachate, particularly cobalt is selectively extracted as a cobalt
recovery solution to obtain a nickel sulfate solution having a low
cobalt concentration.
[0047] Note that as ammonia water used for pH adjustment in this
step, ammonia water generated in an ammonia recovery step described
later can also be used.
[0048] (1) Hydroxylation Step
[0049] In the present invention, an alkali is added to a nickel
sulfate solution obtained, for example, through the above-described
steps to generate a precipitate of nickel hydroxide, and the
precipitate as a solid component and a liquid component are
separated from each other.
[0050] By this treatment, many of impurities contained in nickel
sulfate are separated into the liquid component. This enables to
reduce the concentration of impurities contained in the precipitate
of nickel hydroxide, which is a solid component.
[0051] As the alkali to be added, it is preferable to use one that
can be prepared industrially at low cost and in large quantities,
such as sodium hydroxide or calcium hydroxide.
[0052] (2) Complexation Step
[0053] This complexation step specifically includes two steps of a
dissolving step and a seed crystal adding step. First, in the
dissolving step, to nickel hydroxide which is the precipitate
obtained in the hydroxylation step (1), ammonia in a form of a
final reduction solution obtained by solid/liquid separation of the
reduced slurry obtained in the reduction step (3) is added to form
a mixed solution of nickel hydroxide and the final reduction
solution. The mixed solution is thereby subjected to a complexation
treatment to generate a nickel sulfate amine complex which is an
amine complex of nickel, and thus forming a nickel amine complex
solution.
[0054] At this time, an ammonia concentration can be adjusted by
adding an ammonia gas or ammonia water. At this time, ammonia is
added such that the ammonia concentration is 1.9 or more in a molar
ratio with respect to a nickel concentration in the solution. When
the ammonium concentration of ammonia added is less than 1.9,
nickel does not form an amine complex, and a precipitate of nickel
hydroxide is generated.
[0055] In addition, in order to adjust an ammonium sulfate
concentration, ammonium sulfate can be added in this step.
[0056] At this time, the ammonium sulfate concentration is
preferably 100 to 500 g/L. When the ammonium sulfate concentration
exceeds 500 g/L, the ammonium sulfate concentration exceeds a
solubility, and crystals are precipitated. It is difficult to
attain that the ammonium sulfate concentration is less than 100 g/L
due to a metal balance in the process.
[0057] Furthermore, as the ammonia gas or the ammonia water used in
this step, an ammonia gas or ammonia water generated in an ammonia
recovery step described later can be used.
[0058] Furthermore, following the dissolving step, a seed crystal
adding step is performed in which a nickel powder having an average
particle size of 0.1 to 100 .mu.m is added as a seed crystal in a
form of a nickel powder slurry to the generated nickel sulfate
amine complex solution to form a mixed slurry containing the seed
crystal, the nickel sulfate amine complex solution, and nickel
hydroxide.
[0059] The weight of the seed crystal added at this time is
preferably 1 to 100% with respect to the weight of nickel in the
nickel sulfate amine complex solution. When the above ratio is less
than 1%, reaction efficiency is significantly reduced at the time
of reduction in a subsequent step. When the above ratio exceeds
100%, the amount used is large, and manufacture of the seed crystal
is costly and not economical.
[0060] In addition, a dispersant may be added at the same time.
Since the seed crystals are dispersed by adding the dispersant, the
efficiency can be increased in a subsequent reduction step.
[0061] The dispersant used here is not particularly limited as long
as containing a sulfonate, but a lignin sulfonate is preferable
because the lignin sulfonate can be obtained industrially at low
cost.
[0062] (3) Reduction Step
[0063] In this reduction step, a hydrogen gas is blown into the
obtained mixed slurry, a nickel component in the solution is
reduced, and the nickel component is precipitated on the seed
crystal to form a reduced slurry containing a nickel powder.
[0064] At this time, the reaction temperature is preferably 100 to
200.degree. C. When the temperature is lower than 100.degree. C.,
more preferably lower than 150.degree. C., reduction efficiency
decreases. Even when the temperature is higher than 200.degree. C.,
there is no influence on the reaction, and a loss in thermal energy
or the like increases.
[0065] The pressure during the reaction is preferably 0.8 to 4.0
MPa. When the pressure is less than 0.8 MPa, reaction efficiency is
reduced. Even when the pressure exceeds 4.0 MPa, there is no
influence on the reaction, and a loss in hydrogen gas
increases.
[0066] Note that in the liquid of the obtained mixed slurry, a
magnesium ion, a sodium ion, a calcium ion, a sulfate ion, and an
ammonium ion are mainly present as impurities, but all of these
ions remain in the solution. Therefore, a high-purity nickel powder
can be generated.
[0067] In addition, nickel hydroxide in the liquid of the mixed
slurry reacts with an ammonium ion generated by the reduction
reaction, is dissolved as a nickel amine complex in the solution,
and is reduced by reacting with a hydrogen gas to precipitate
nickel on the seed crystal.
[0068] (4) Solid/Liquid Separation Step
[0069] The reduced slurry generated in the previous reduction step
(3) is solid/liquid separated to recover a high-purity nickel
powder with a small amount of impurities and a final reduction
solution. The high-purity nickel powder is repeatedly supplied to
the complexation step (2) and/or the reduction step (3), in which
the high-purity nickel powder is used as a seed crystal in the
complexation step (2), and is used as a nickel powder to be
subjected to particle growth in the reduction step (3).
[0070] Meanwhile, the recovered final reduction solution is
repeatedly supplied as a substitute for ammonia water in the
complexation step (2).
[0071] That is, out of the recovered high-purity nickel powder with
a small amount of impurities, a small-sized nickel powder or a
nickel powder having a reduced size by grinding or the like is
repeatedly supplied as a seed crystal to the complexation step (2).
Here, the nickel powder is further added to the nickel sulfate
amine complex solution obtained in the complexation step (2). In
the reduction step (3), a hydrogen gas is supplied thereto, and
nickel is thereby further reduced and precipitated on the
high-purity nickel powder. Therefore, the particles can be
grown.
[0072] In addition, by the repeated supply to the reduction step a
plurality of times, a high-purity nickel powder having a higher
bulk density and a larger particle size can also be generated.
[0073] Furthermore, the obtained high-purity nickel powder may be
processed into a briquette shape which is coarser, hardly oxidized,
and easily handled through the following nickel powder briquetting
step or briquette firing step.
[0074] An ammonia recovery step may be further provided.
[0075] [Nickel Powder Briquetting Step]
[0076] The high-purity nickel powder manufactured by the present
invention is dried and then formed into a massive nickel briquette
as a product form by a briquetting machine or the like.
[0077] In order to improve formability into the briquette, a
substance that does not contaminate a product quality, such as
water, may be added to the nickel powder as a binder in some
cases.
[0078] [Briquette Sintering Step]
[0079] The nickel briquette prepared in the briquetting step is
roasted and sintered in a hydrogen atmosphere to prepare a
briquette sintered body. This treatment increases the strength and
removes trace amounts of residual ammonia and sulfur components.
The roasting and sintering temperature is preferably 500 to
1200.degree. C. When the temperature is lower than 500.degree. C.,
sintering is insufficient. Even when the temperature is higher than
1200.degree. C., efficiency hardly changes, and a loss in energy
increases.
[0080] (5) Nickel Recovery Step
[0081] Nickel remains in the final reduction solution generated in
the solid/liquid separation step (4). When the amount of residual
nickel is large, the nickel may be mixed into an ammonium sulfate
crystal generated in a subsequent ammonium sulfate recovery step to
contaminate the quality of the ammonium sulfate crystal. Therefore,
it is necessary to remove the residual nickel in advance.
[0082] A sulfurizing agent used here may be an industrially used
sulfurizing agent such as a hydrogen sulfide gas or sodium hydrogen
sulfide, but is preferably a hydrogen sulfide gas in order to
further improve the quality of the ammonium sulfate crystal.
[0083] (6) Nickel regeneration step Nickel sulfide precipitated by
adding a sulfurizing agent is solid/liquid separated and recovered.
Thereafter, the recovered nickel sulfide can be leached again, and
repeatedly supplied to the system. In this leaching, when nickel
sulfide recovered in the previous nickel recovery step is leached
dedicatedly and singly, there are few disadvantages such as
impurities, and high efficiency is preferably obtained. In
addition, when nickel sulfide recovered in the previous nickel
recovery step is repeatedly supplied to the above [leaching step]
as one of the starting raw materials described above, equipment
saving can be achieved, which is preferable. Note that a nickel
post-reduction solution in the aqueous phase is sent to a
subsequent step.
[0084] [Ammonium Sulfate Recovery Step]
[0085] The nickel post-reduction solution generated in the above
[nickel recovery step] contains ammonium sulfate and ammonia.
[0086] Therefore, the solution after reaction is heated and
concentrated through an ammonium sulfate recovery step to
crystallize ammonium sulfate, and ammonium sulfate can be recovered
as an ammonium sulfate crystal.
[0087] [Ammonia Recovery Step]
[0088] By adding an alkali to the final reduction solution,
adjusting the pH to 10 to 13, and then heating the resulting
solution, an ammonia gas is volatilized, and ammonia can be
recovered.
[0089] The alkali used here is not particularly limited, but
caustic soda, slaked lime, and the like are industrially
inexpensive and suitable.
[0090] Furthermore, by bringing the recovered ammonia gas into
contact with water, ammonia water can be generated, and the
obtained ammonia water can be repeatedly used in a step.
EXAMPLES
[0091] Hereinafter, the present invention will be described in more
detail with reference to Examples.
Example 1
[0092] By adding 800 ml of slaked lime adjusted so as to have a
slurry concentration of 200 g/L to 1000 ml of a nickel sulfate
solution having a nickel concentration of 120 g/L, 116 g of nickel
hydroxide was obtained.
[0093] The nickel hydroxide was added to 1700 ml of a mixed
solution of a nickel sulfate solution having a nickel concentration
of 30 g/L and an ammonium sulfate solution having an ammonia
concentration of 40 g/L together with 12.8 g of nickel powder
having an average particle size of 2 .mu.m as a seed crystal, and
the resulting mixture was stirred to prepare a mixed slurry.
[0094] This mixed slurry was heated to 185.degree. C. while being
stirred in an autoclave. A hydrogen gas was blown and supplied into
the autoclave such that the pressure in the autoclave became 3.5
MPa to be subjected to the reduction step. Thereafter, the
resulting product was subjected to the solid/liquid separation step
by filtration, and a nickel powder with particle growth was
recovered.
[0095] At this time, the recovered nickel powder had an average
particle size of 65 .mu.m and a recovery amount of 119 g.
[0096] Furthermore, the recovered nickel powder was washed with
pure water, and then the impurity grade of the nickel powder was
analyzed.
[0097] Results thereof are illustrated in Table 1. Mg or Na was not
mixed into the nickel powder, and a high-purity nickel powder could
be generated.
TABLE-US-00001 TABLE 1 Ni Mg Na Example 1 -- <0.005%
<0.005%
Example 2
[0098] By adding 800 ml of slaked lime adjusted so as to have a
slurry concentration of 200 g/L to 1000 ml of a nickel sulfate
solution having a nickel concentration of 120 g/L, 116 g of nickel
hydroxide was obtained.
[0099] The 116 g of nickel hydroxide was mixed with a nickel
sulfate amine complex solution having a nickel concentration of 30
g/L, 232 ml of 25% ammonia water, and 225 g of ammonium sulfate,
and pure water was added thereto to prepare 1000 ml of mixed
slurry. To this solution, 20 g of nickel powder having an average
particle size of 1 .mu.m was added as a seed crystal to prepare a
mixed slurry.
[0100] Next, the prepared mixed slurry was heated to 120.degree. C.
while being stirred in an autoclave. A hydrogen gas was blown and
supplied into the autoclave such that the pressure in the autoclave
became 3.5 MPa to perform a nickel powder generation treatment
which is a reduction treatment.
[0101] One hour after the supply of the hydrogen gas, the supply of
the hydrogen gas was stopped, and the autoclave was cooled. The
reduced slurry obtained after cooling was subjected to the
solid/liquid separation treatment by filtration, and a high-purity
and small-size nickel powder was recovered. The recovered nickel
powder at this time was 70 g.
[0102] Next, 116 g of nickel hydroxide was added to the final
reduction solution after the solid/liquid separation to prepare a
slurry. To the slurry, the whole amount of the recovered
high-purity and small-size nickel powder was added to prepare a
mixed slurry.
[0103] The mixed slurry was heated to 120.degree. C. while being
stirred in an autoclave. A hydrogen gas was blown and supplied into
the autoclave such that the pressure in the autoclave became 3.5
MPa.
[0104] One hour after the supply of the hydrogen gas, the supply of
the hydrogen gas was stopped, and the autoclave was cooled. The
slurry obtained after cooling was solid/liquid separated by
filtration, and a high-purity nickel powder with particle growth
was recovered.
Example 3
[0105] Using the final reduction solution obtained in the
solid/liquid separation step in Example 1 as a part of an ammonia
source, a mixed slurry was prepared, subjected to the reduction
step under the same conditions as in Example 1, and subjected to
the solid/liquid separation step, and a nickel powder with particle
growth was recovered. A nickel powder similar to that in Example 1
was recovered.
Example 4
[0106] To a solution containing a nickel powder prepared under the
same conditions as in Example 1, 336 g of nickel sulfate, and 330 g
of ammonium sulfate, 191 ml of 25% ammonia water was added, and a
total liquid volume was adjusted to 1000 ml. Thereafter, the
resulting solution was again subjected to the reduction step under
the same conditions as in Example 1 and the solid/liquid separation
step to prepare a nickel powder with particle growth. Using the
nickel powder thus prepared, the same operation was repeated 10
times to cause particle growth of the nickel powder.
[0107] The average particle size of the recovered nickel powder was
111 .mu.m, and the nickel powder caused particle growth so as to be
1.7 times larger than the nickel powder in Example 1.
[0108] The nickel powder obtained by these repeated operations had
a sulfur grade of 0.04%. The amount of each of sodium and magnesium
was below a lower quantification limit as in Table 1 above.
[0109] Furthermore, the obtained nickel powder was heated to
1000.degree. C. in a 2% hydrogen atmosphere and held for 60
minutes. The nickel powder obtained after being thus held had a
sulfur grade of 0.008%, and the sulfur grade could be further
reduced by roasting.
Example 5
[0110] To 1000 ml of a nickel sulfate amine complex solution
illustrated in Table 2, 75 g of nickel powder having an average
particle size of 1 .mu.m was added as a seed crystal. Thereafter,
the resulting mixture was heated to 185.degree. C. while being
stirred in an autoclave, and a hydrogen gas was blown and supplied
into the autoclave such that the pressure in the autoclave became
3.5 MPa.
[0111] One hour after the supply of the hydrogen gas, the supply of
the hydrogen gas was stopped, and the autoclave was cooled. The
slurry obtained after cooling was solid/liquid separated by
filtration. The recovered nickel powder was washed with pure water.
Thereafter, the impurity grade of the nickel powder was
analyzed.
[0112] Results thereof are illustrated in Table 2.
[0113] Mg or Na was not mixed into the nickel powder, and a
high-purity nickel powder could be generated.
TABLE-US-00002 TABLE 2 Ni Mg Na Example 5 Nickel sulfate 75 [g/L]
0.1 [g/L] 7.0 [g/L] ammine complex solution High-purity --
<0.005% <0.005% nickel powder
Example 6
[0114] 75 g of nickel hydroxide was added to a nickel sulfate amine
complex solution prepared by mixing 135 g of nickel sulfate
hexahydrate, 191 ml of 25% ammonia water, 169 g of ammonium
sulfate, and pure water, and pure water was added thereto such that
the liquid volume became 1000 ml. 15 g of nickel powder having an
average particle size of 1 .mu.m was added thereto as a seed
crystal to prepare a mixed slurry.
[0115] The mixed slurry was heated to 100.degree. C. while being
stirred in an autoclave. A hydrogen gas was supplied into the
autoclave such that the pressure in the autoclave became 3.5 MPa to
perform a nickel powder generation treatment.
[0116] One hour after the supply of the hydrogen gas, the supply of
the hydrogen gas was stopped, and the autoclave was cooled. The
reduced slurry obtained after cooling was subjected to a
solid/liquid separation treatment by filtration, and a high-purity
and small-size nickel powder was recovered. At this time, a nickel
reduction ratio was 58%.
Example 7
[0117] Using the same mixed slurry as in Example 6, the same
operation as in Example 6 was performed under the conditions of a
temperature of 100.degree. C. and a pressure in the autoclave of
0.8 MPa. At this time, a nickel reduction ratio was 56%.
Example 8
[0118] Using the same mixed slurry as in Example 6, the same
operation as in Example 6 was performed under the conditions of a
temperature of 120.degree. C. and a pressure in the autoclave of
3.5 MPa. At this time, a nickel reduction ratio was 74%.
Example 9
[0119] Using the same mixed slurry as in Example 6, the same
operation as in Example 6 was performed under the conditions of a
temperature of 120.degree. C. and a pressure in the autoclave of
2.0 MPa. At this time, a nickel reduction ratio was 74%.
Example 10
[0120] Using the same mixed slurry as in Example 6, the same
operation as in Example 6 was performed under the conditions of a
temperature of 120.degree. C. and a pressure in the autoclave of
1.5 MPa. At this time, a nickel reduction ratio was 74%.
[0121] As can be seen from the results of Examples 6 to 10
illustrated in Table 3, high-purity nickel was generated in all the
cases, and it is found that the reduction ratio is not
significantly affected by the pressure and is significantly reduced
due to a temperature decrease.
TABLE-US-00003 TABLE 3 Ni Temperature Pressure reduction [.degree.
C.] [MPa] ratio [%] Example 6 100 3.5 58 Example 7 100 0.8 56
Example 8 120 3.5 74 Example 9 120 2.0 74 Example 10 120 1.5 74
Comparative Example 1
[0122] A nickel powder was prepared under the same conditions as in
Example 1 except that without performing the hydroxylation step in
Example 1, 7.5 g of nickel powder having an average particle size
of 1 .mu.m was added, as a seed crystal, to a solution prepared by
adding 191 ml of 25% ammonia water to a solution containing a
nickel sulfate solution containing 75 g of nickel and 330 g of
ammonium sulfate, and adjusting the total liquid volume to 1000 ml,
to prepare a mixed slurry.
[0123] The recovered nickel powder was washed with pure water, and
then the impurity grade of the nickel powder was analyzed.
[0124] Results thereof are illustrated in Table 4. The amount of Mg
or Na mixed into the nickel powder was larger than that in Example
1. Note that the average particle size and the recovery amount were
almost the same as those in Example 1.
TABLE-US-00004 TABLE 4 Ni Mg Na Comparative Example 1 -- 0.02%
0.02%
Comparative Example 2
[0125] Using the same method as in Comparative Example 1, a nickel
powder was prepared without performing the hydroxylation step. The
operation was performed on the nickel powder repeatedly 10 times in
the same manner as in Example 3 to particle growth. The nickel
powder obtained by these repeated operations had a sulfur grade of
0.1%. It was not possible to obtain such a high-purity nickel
powder having a sulfur grade of about 0.04% as obtained in Example
3 of the present invention.
Example 11
[0126] According to a component analysis of the final reduction
solution generated in Example 1, it is found that 1 g/L of nickel
remained in the final reduction solution.
[0127] Therefore, the final reduction solution was put in an
airtight vessel, heated to 60.degree. C., and sulfurated by blowing
a hydrogen sulfide gas thereinto in a total volume of 1.0 L while
being stirred. Thereafter, the resulting solution was solid/liquid
separated to obtain nickel sulfide and a nickel post-reduction
solution. The nickel concentration in the obtained nickel
post-reduction solution was reduced to 0.01 g/L, and it is found
that that most of nickel was recovered as nickel sulfide.
* * * * *