U.S. patent application number 15/770546 was filed with the patent office on 2019-02-28 for method for producing seed crystal of cobalt powder.
The applicant listed for this patent is SUMITOMO METAL MINING CO., LTD.. Invention is credited to Yasuo Doi, Shin-ichi Heguri, Osamu Ikeda, Yohei Kudo, Yoshitomo Ozaki, Kazuyuki Takaishi, Ryo-ma Yamaguma.
Application Number | 20190061006 15/770546 |
Document ID | / |
Family ID | 58630124 |
Filed Date | 2019-02-28 |
United States Patent
Application |
20190061006 |
Kind Code |
A1 |
Ikeda; Osamu ; et
al. |
February 28, 2019 |
METHOD FOR PRODUCING SEED CRYSTAL OF COBALT POWDER
Abstract
Provided is a method for producing seed crystals of cobalt
powder, sequentially including: a complexing step of adding
ammonia, an ammonia compound solution, or both of ammonia and an
ammonia compound solution to a cobalt sulfate solution to obtain a
solution containing a cobalt ammine sulfate complex; a mixing step
of adding a solid to the solution containing the cobalt ammine
sulfate complex to form a mixture slurry; a reduction and
precipitation step of charging a reaction vessel with the mixture
slurry, blowing hydrogen gas into the reaction vessel and reducing
cobalt contained in the mixture slurry to obtain a cobalt powder
slurry containing cobalt precipitate with a cobalt component
precipitated on the surface of the solid as cobalt powder; and a
solid-liquid separation step of performing solid-liquid separation
on the cobalt powder slurry to obtain cobalt precipitate and a
solution after reduction.
Inventors: |
Ikeda; Osamu; (Niihama-shi,
JP) ; Yamaguma; Ryo-ma; (Niihama-shi, JP) ;
Ozaki; Yoshitomo; (Niihama-shi, JP) ; Takaishi;
Kazuyuki; (Niihama-shi, JP) ; Heguri; Shin-ichi;
(Niihama-shi, JP) ; Kudo; Yohei; (Niihama-shi,
JP) ; Doi; Yasuo; (Niihama-shi, JP) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
SUMITOMO METAL MINING CO., LTD. |
Tokyo |
|
JP |
|
|
Family ID: |
58630124 |
Appl. No.: |
15/770546 |
Filed: |
October 17, 2016 |
PCT Filed: |
October 17, 2016 |
PCT NO: |
PCT/JP2016/080690 |
371 Date: |
April 24, 2018 |
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
B22F 2999/00 20130101;
C22C 1/0433 20130101; B22F 9/26 20130101; B22F 2301/15 20130101;
B22F 2304/10 20130101; B22F 2999/00 20130101; B22F 9/24 20130101;
C22C 1/0433 20130101 |
International
Class: |
B22F 9/26 20060101
B22F009/26 |
Foreign Application Data
Date |
Code |
Application Number |
Oct 26, 2015 |
JP |
2015-210258 |
Claims
1. A method of producing seed crystals of cobalt powder,
sequentially comprising: a complexing step of adding ammonia, an
ammonia compound solution, or both of ammonia and an ammonia
compound solution to a cobalt sulfate solution to obtain a solution
containing a cobalt ammine sulfate complex; a mixing step of adding
nickel powder as a solid that is insoluble or slightly soluble in
the solution containing the cobalt ammine sulfate complex, to the
solution containing the cobalt ammine sulfate complex obtained in
the complexing step to form a mixture slurry; a reduction and
precipitation step of charging a reaction vessel with the mixture
slurry obtained in the mixing step, and blowing hydrogen gas into
the reaction vessel to reduce cobalt contained in the mixture
slurry and obtain a cobalt powder slurry containing cobalt
precipitate with a cobalt component precipitated on a surface of
the solid as cobalt powder; and a solid-liquid separation step
having a solid-liquid separation treatment for separating the
cobalt powder slurry obtained into the cobalt precipitate and a
solution after reduction, and a solid separation treatment for
separating the cobalt precipitate obtained into the nickel powder
of the solid added and the cobalt powder that is precipitated on
the surface of the nickel powder of the solid, to form the solution
after reduction, the nickel powder of the solid, and the cobalt
powder.
2. The method of producing seed crystals of cobalt powder according
to claim 1, wherein the nickel powder of the solid has an average
particle size of 0.1 to 5 .mu.m.
3. The method of producing seed crystals of cobalt powder according
to claim 2, wherein a cobalt concentration in the solution
containing the cobalt ammine sulfate complex is 75 g/L or less.
4-5. (canceled)
6. The method of producing seed crystals of cobalt powder according
to claim 1, wherein a cobalt concentration in the solution
containing the cobalt ammine sulfate complex is 75 g/L or less.
Description
BACKGROUND
Field of the Invention
[0001] The present invention relates to a method for producing
cobalt powder from a solution containing a cobalt ammine sulfate
complex, and particularly relates to a method for obtaining seed
crystals to use for crystal growth.
Description of the Related Art
[0002] Various methods for obtaining cobalt, which is used as an
electronic material or heat resistant alloys, have been known. In
recent years, a demand for cobalt salts, which become raw materials
such as battery materials, has been increased.
[0003] The cobalt salts are generally produced by dissolving a
cobalt metal in an acid. However, sheet-shaped and massive forms
such as conventionally common electrolytic cobalt are easily
handled, but are extremely slowly dissolved in an acid. Meanwhile,
the form of fine powder is easily dissolved in an acid, but has the
handling disadvantage of being easily scattered and the like. Ones
called briquets and obtained by consolidating or sintering grains
or powder are preferred to make good use of the advantages of the
both.
[0004] As a method for obtaining such a small size of cobalt grains
or powder, an atomizing method for dispersing melted cobalt in gas
or water to obtain fine powder and a dry method such as CVD for
obtaining cobalt powder by volatilizing cobalt and reducing it in a
gas phase as shown in Japanese Patent Laid-Open No. 2005-505695 are
known.
[0005] As a method for producing cobalt powder by a wet process,
there are a method for generating it using a reducing agent as
shown in Japanese Patent Laid-Open No. 2010-242143 and a spray
thermal decomposition method for obtaining cobalt powder by a
thermal decomposition reaction by spraying a cobalt solution in a
reduction atmosphere at a high temperature as shown in Japanese
Patent No. 4286220, and the like.
[0006] However, since these methods require expensive reagents and
a large amount of energy, they are not economical as methods for
industrially obtaining a large amount of material for the battery
materials or the like.
[0007] There has remained a problem that in a method for growing
using cobalt powder as seed crystals as shown in Japanese Patent
Laid-Open No. S57-54207, seed crystals and grown cobalt powder are
remelted, resulting in a decrease in the recovery since the
reaction is performed in an acidic solution having a pH of 4 or
less.
[0008] Additionally, there has remained a problem that, in a method
for adding a sodium hydroxide solution to a cobalt sulfate solution
for a raw material and performing hydrogen reduction, the hydroxide
of cobalt is generated and thereby allowing a reduction reaction
not to proceed when the pH cannot be maintained at 4 and increases,
and consequently the efficiency in the reduction reaction
decreases.
[0009] Meanwhile, a method for feeding hydrogen gas to a cobalt
ammine sulfate complex solution having cobalt in the form of an
ammonia complex to reduce cobalt ions in the complex solution and
obtain cobalt powder as shown in "The Manufacture and properties of
Metal powder produced BY the gaseous reduction of aqueous
solutions", Powder metallurgy, No. 1/2 (1958), pp 40-52 is
industrially low-priced and useful.
[0010] However, also in this method, there is a problem that many
crystal nuclei are generated heterogeneously, resulting in the
prevention of the growth in the same way as the above-mentioned
prior arts since particles are intended to be generated from a
solution and grow by a wet reaction. That is, it is essential to
control the number of the generated nuclei of the crystal in a
proper range, resulting in efficient growth.
[0011] Then, as mentioned above, a method for feeding a reducing
agent to a slurry in which a small amount of fine crystals called
seed crystals coexist, and growing objects on the surfaces of the
seed crystals to obtain powder having a predetermined particle size
is commonly used.
[0012] The seed crystals added in the above are often used by
conducting treatment such as grinding a portion of a product
repeatedly. However, there has remained a problem that the
processing also took time and effort and the yield decreased as the
processing is repeated more times and therefore this lead to an
increase in cost. There has' also remained the problem of seed
crystals having the optimal particle size and properties being
capable of necessarily being obtained stably only by grinding
simply, or the like.
[0013] That is, a method for stably obtaining seed crystals to use
for crystal growth has been required.
[0014] In such a situation, the present invention provides a
production method for obtaining cobalt powder efficiently by a way
for increasing reduction reaction efficiency to produce the cobalt
powder from a solution containing a cobalt ammine sulfate
complex.
SUMMARY
[0015] A first aspect of the present invention to solve such a
problem is a method for producing seed crystals of cobalt powder,
sequentially including: a complexing step of adding ammonia, an
ammonia compound solution, or both of ammonia and an ammonia
compound solution to a cobalt sulfate solution to obtain a solution
containing a cobalt ammine sulfate complex; a mixing step of adding
nickel powder as a solid that is insoluble or slightly soluble in
the solution containing the cobalt ammine sulfate complex, to the
solution containing the cobalt ammine sulfate complex obtained in
the complexing step to form a mixture slurry; a reduction and
precipitation step of charging a reaction vessel with the mixture
slurry obtained in the mixing step, and blowing hydrogen gas into
the reaction vessel to reduce cobalt contained in the mixture
slurry and obtain a cobalt powder slurry containing cobalt
precipitate with a cobalt component precipitated on the surface of
the solid as cobalt powder; and a solid-liquid separation step
having a solid-liquid separation treatment for separating the
obtained cobalt powder slurry into the cobalt precipitate and a
solution after reduction, and a solid separation treatment for
separating the obtained cobalt precipitate into the added nickel
powder of the solid and the cobalt powder that is precipitated on
the surface of the nickel powder of the solid, to form the solution
after reduction, the nickel powder of the solid, and the cobalt
powder.
[0016] A second aspect of the present invention is the method for
producing seed crystals of cobalt powder, wherein the nickel powder
of the solid in the first aspect has an average particle size of
0.1 .mu.m or more and 5 .mu.m or less.
[0017] A third aspect of the present invention is the method for
producing seed crystals of cobalt powder, wherein the cobalt
concentration in the solution containing the cobalt ammine sulfate
complex in the first and second aspects is 75 g/L or less.
[0018] According to the present invention, seed crystals having a
size suitable to be add to a cobalt ammine sulfate complex solution
as seed crystals to form cobalt powder can be obtained efficiently
when a cobalt ammine sulfate complex solution is reduced with
hydrogen gas to produce cobalt powder.
BRIEF DESCRIPTION OF DRAWING
[0019] FIG. 1 is a production flow chart of the method for
producing cobalt powder according to the present invention.
DETAILED DESCRIPTION
[0020] The present invention is a method for efficiently producing
seed crystals to be add when hydrogen gas is blown into a cobalt
ammine sulfate complex solution to produce cobalt powder.
[0021] Hereinafter, the method for producing cobalt powder
according to the present invention will described with reference to
the production flow chart shown in FIG. 1. In the present
invention, cobalt powder is obtained by subjecting a cobalt sulfate
solution serving as an original solution to a complexing step, a
mixing step, a reduction and precipitation step and a solid-liquid
separation step.
[0022] The reduction rate mentioned in the present invention is
defined as a rate obtained by dividing the weight (g) of the
obtained cobalt powder by the cobalt amount (g/L) contained in the
fed cobalt sulfate solution
[Complexing Step]
[0023] A cobalt sulfate solution that can be used in the present
invention is not particularly limited, but a cobalt leachate
obtained by leaching/dissolving a cobalt-containing material such
as an industrial intermediate comprising one or a mixture of two or
more selected from mixed sulfide containing cobalt, crude cobalt
sulfate, cobalt oxide, cobalt hydroxide, cobalt carbonate, cobalt
powder, and the like with sulfuric acid or ammonia can be used.
Usually, various impurities are also industrially contained in the
cobalt leachate. The leachate is generally used by removing
impurity elements in the leachate by subjecting the leachate to a
purification step such as solvent extraction, ion exchange, or
neutralization.
[0024] Next, aqueous ammonia and ammonium sulfate are added to the
cobalt leachate to obtain a cobalt ammine sulfate complex
solution.
[0025] The concentration of ammonium sulfate in the solution is
preferably in the range of 10 to 500 g/L. If the concentration is
more than 500 g/L, it is higher than the solubility, and crystals
may be precipitated. This is not preferable since an operational
trouble occurs. If the concentration is less than 10 g/L, since
ammonium sulfate is newly produced by the reaction, it is
industrially difficult to keep the concentration at a level of less
than 10 g/L.
[0026] The cobalt concentration in the cobalt ammine sulfate
complex solution is 75 g/L or less. It is because in the reaction
of a solid after the addition in later steps, if the cobalt
concentration in the cobalt ammine sulfate complex solution is too
high, the reduction rate will be decreased due to the shortage of
reaction sites.
[Mixing Step]
[0027] In this step, to the cobalt ammine sulfate complex solution
prepared as described above is added a solid that is used as a
matrix for precipitation.
[0028] The solid to be added is not particularly limited as long as
it is insoluble or sparingly soluble with a low solubility in a
cobalt ammine sulfate complex solution, an aqueous ammonium sulfate
solution, or an alkali solution.
[0029] Specifically, it is preferable to use nickel powder.
[0030] When cobalt powder is used for a solid, it is the same as
cobalt precipitate, and therefore these do not need to be
separated. Cobalt powder is thus the most suitable to be used as
seed crystals, but it is difficult to industrially obtain fine
cobalt powder at a low price stably.
[0031] Although there is an advantage of iron powder being
available at a low price easily, there is a disadvantage of iron
powder being easily dissolved in an acidic solution and hardly
serving as crystal nuclei. Because dissolved iron ions becomes a
new cause of contamination, and the like, iron powder is not
suitable.
[0032] In a method for using a slightly soluble or insoluble solid
and precipitating cobalt thereon like the present invention, the
influence of remelting is so avoidable as to be negligible and it
is not necessary to repeat some of product, differently from a
method for precipitating cobalt using seed crystals that is
generally used conventionally and forming the cobalt including the
seed crystals into a product. Therefore, there is a characteristic
that cobalt complex ions contained in an ammine complex solution
can be reduced nearly completely in a viewpoint of the balance
between the amounts of materials in the process.
[0033] It is preferable that the solid have a smooth surface so
that the precipitated cobalt powder can be separated effectively.
As mentioned above, the amount of the solid added equivalent to the
amount of cobalt existing in the solution or more is required.
Specifically, when nickel powder is used for a solid, 75 g/L or
more need to be added.
[Reduction and Precipitation Step]
[0034] Next, the reaction vessel of a pressure vessel is charged
with the slurry formed by adding nickel powder in the mixing step,
and cobalt complex ions in the slurry is reduced by blowing a
reducing agent such as hydrogen gas into the reaction vessel to
precipitate cobalt on the surface of the solid.
[0035] Here, the temperature of the mixture slurry, namely, the
reaction temperature, is preferably in the range of 150 to
200.degree. C. If the reaction temperature is less than 150.degree.
C., reduction efficiency is decreased, and even if the reaction
temperature is higher than 200.degree. C., the reaction is not
affected, but the loss of thermal energy increases.
[0036] The pressure of the gas phase part, which is a space other
than the solution in the reaction vessel, is preferably maintained
in the range of 1.0 to 4.0 MPa by feeding hydrogen gas. If the
pressure is less than 1.0 MPa, reaction efficiency is reduced since
the amount of gas migrating from the gas phase part into the
solution is little. Meanwhile, even if the pressure is higher than
4.0 MPa, there is no influence such as the reaction being enhanced,
but the loss of hydrogen gas just increases, resulting in no
advantage.
[0037] Hydrogen gas may be blown into the gas phase part in the
reaction vessel or blown directly into the slurry.
[Solid-Liquid Separation Step]
[0038] The solid having cobalt precipitate on the surface obtained
in the reduction and precipitation step is taken out of the
pressure vessel with the solution after reduction in the pressure
vessel and subjected to solid-liquid separation from the solution
after reduction.
[0039] This solid-liquid separation may be any of, for example, a
method using a nutsche and a vacuum flask, a method using a
centrifuge, a method using a filter press.
[0040] Then, when a substance other than cobalt is used for the
solid, operation of separating the cobalt precipitate on the
surface from the solid may be performed.
[0041] Specific separation method can be properly performed by
applying a shock to the solid and the cobalt precipitate, or the
like.
[0042] When the size of the cobalt precipitate still including the
solid or the cobalt precipitate after separation from the solid is
still smaller than that used for seed crystals, the size of the
cobalt precipitate can be increased by repeating the mixing step
again.
[0043] The solid collected here can be reused for the mixing step
repeatedly.
[0044] The solution after reduction can be used repeatedly as a
complexing agent in the complexing step without any treatment or by
the recycling thereof into ammonia by treatment such as heating and
distillation.
EXAMPLES
[0045] Examples for generating seed crystals for obtaining cobalt
powder of the present invention will be described below.
[0046] The average particle size was measured using a commercial
laser particle size analyzer (Microtrac).
Example 1
[0047] A solution containing a cobalt ammine sulfate complex was
prepared by adding 191 ml of 25% aqueous ammonia to cobalt sulfate
equivalent to 75 g of cobalt and 330 g of ammonium sulfate,
dissolving them and adjusting the total volume of the solution to
1000 ml.
[0048] To this solution was added 75 g of nickel powder having an
average particle size of 1 .mu.m and used as a matrix for
precipitation to obtain a mixture slurry.
[0049] Next, an inner cylinder of an autoclave having a volume of 3
L was charged with the mixture slurry, the mixture slurry was then
heated to 185.degree. C. with stirring, hydrogen gas was blown into
the mixture slurry while keeping the temperature, and hydrogen gas
was further fed so as to maintain the pressure in the inner
cylinder of the autoclave at 3.5 MPa. After a lapse of 60 minutes
from the start of the feeding of hydrogen gas, the feeding of
hydrogen gas was stopped, and the inner cylinder was cooled.
[0050] After cooling to room temperature, the mixture slurry in the
inner cylinder was filtered, and the insoluble solid having cobalt
precipitate formed on the surface was removed. Then, solid-liquid
separation was conducted by suction filtration using a vacuum flask
and a nutsche.
[0051] The reduction reaction rate of cobalt at this time was
99%.
Comparative Example 1
[0052] A solution containing a cobalt ammine sulfate complex was
prepared by obtaining a solution containing 75 g of cobalt, 330 g
of ammonium sulfate and 191 ml of 25% aqueous ammonia, adding 3.73
g of polyacrylic acid having a concentration of 40 wt % as a
dispersant instead of a solid of seed crystals of the present
invention thereto, and adjusting the total volume of the solution
to 1000 ml.
[0053] The same inner cylinder of the autoclave as Example 1 was
charged with the prepared solution, which was then heated to
185.degree. C. with stirring, hydrogen gas was blown into the
mixture slurry while keeping the temperature, and hydrogen gas was
further fed so as to maintain the pressure in the inner cylinder of
the autoclave at 3.5 MPa.
[0054] After a lapse of 60 minutes from the start of the feeding of
hydrogen gas, feeding hydrogen gas was stopped, and the inner
cylinder was cooled.
[0055] After cooling to room temperature, the solution in the inner
cylinder was filtered, and the insoluble solid having cobalt
precipitate formed on the surface was removed. Then, solid-liquid
separation was conducted by suction filtration using the vacuum
flask and the nutsche. The cobalt reduction reaction rate at this
time was 72%, and as high efficiency as that of Example of the
present invention was not obtained.
Comparative Example 2
[0056] A solution containing a cobalt ammine sulfate complex was
prepared by adding a solution containing 330 g of ammonium sulfate
to a cobalt sulfate solution containing 75 g of cobalt, adding 191
ml of 25% aqueous ammonia to the resulting solution, and adjusting
the total volume of the solution to 1000 ml.
[0057] To this solution was added 75 g of commercial iron powder
having an average particle size of 1 .mu.m as a solid soluble in
the solution to prepare a mixture slurry.
[0058] The inner cylinder of the autoclave used in Example 1 was
charged with the prepared mixture slurry, the mixture slurry was
then heated to 185.degree. C. with stirring, hydrogen gas was blown
into the mixture slurry while keeping the temperature, and hydrogen
gas was further fed so as to maintain the pressure in the inner
cylinder of the autoclave at 3.5 MPa. After a lapse of 60 minutes
from the start of the feeding of hydrogen gas, the feeding of
hydrogen gas was stopped, and the inner cylinder was cooled.
[0059] After cooling to room temperature, the mixture slurry in the
inner cylinder was filtered, and the iron powder having cobalt
precipitate formed on the surface was removed. Then, solid-liquid
separation was conducted by suction filtration using the vacuum
flask and the nutsche.
[0060] It was found that the cobalt reduction reaction rate as to
this Comparative Example 2 was 76%, which was higher than that in
the case where a conventional dispersant was used, but as high
effect as that of Example of the present invention was not obtained
even if easily soluble solid was added.
* * * * *