WO2017073392A1

WO2017073392A1 - Method for producing seed crystal of cobalt powder

Info

Publication number: WO2017073392A1
Application number: PCT/JP2016/080690
Authority: WO
Inventors: 修池田; 龍馬山隈; 佳智尾崎; 高石　和幸; 伸一平郡; 陽平工藤; 安夫土居
Original assignee: 住友金属鉱山株式会社
Priority date: 2015-10-26
Filing date: 2016-10-17
Publication date: 2017-05-04
Also published as: EP3369499A4; PH12018500896A1; CN108349011A; EP3369499A1; US20190061006A1; AU2016345951B2; JP2017082270A; AU2016345951A1; CA3003239C; CA3003239A1; JP6350830B2; PH12018500896B1

Abstract

Provided is a production method for efficiently obtaining a cobalt powder by means of a process which increases the reduction reaction efficiency during the production of the cobalt powder from a solution that contains a sulfuric acid cobalt ammine complex. A method for producing a seed crystal of a cobalt powder, which is characterized by sequentially performing: a complexing step for obtaining a solution containing a sulfuric acid cobalt ammine complex by adding ammonia and/or a solution of an ammonia compound into a cobalt sulfate solution; a mixing step for obtaining mixed slurry by adding a solid material into the solution containing a sulfuric acid cobalt ammine complex obtained in the complexing step; a reduction/deposition step for obtaining a cobalt powder slurry containing a cobalt deposit, in which the cobalt component is deposited, as a cobalt powder, on the solid material surface, by introducing the mixed slurry obtained in the mixing step into a reactor and reducing cobalt contained in the mixed slurry by blowing a hydrogen gas into the reactor; and a solid-liquid separation step for obtaining the cobalt deposit and the liquid after the reduction by subjecting the cobalt powder slurry obtained in the reduction/deposition step to solid-liquid separation.

Description

Method for producing seed crystal of cobalt powder

The present invention relates to a method for producing cobalt powder from a solution containing a cobalt sulfate ammine complex. In particular, the present invention relates to a method for obtaining a seed crystal used for crystal growth.

Various methods for obtaining cobalt used as electronic materials and heat-resistant alloys are known. In recent years, the demand for cobalt salts as raw materials for battery materials and the like has increased.
These cobalt salts are generally produced by dissolving cobalt metal in an acid, but the conventional sheet and block form such as general electric cobalt are easy to handle, but dissolution in acid is extremely slow, On the other hand, the shape of the fine powder is difficult to handle because it is easy to dissolve in acid, but it is difficult to handle, and in order to take advantage of both, it is preferable to obtain a powder or powder obtained by compacting or sintering briquettes. It is rare.

As a method for obtaining such small-sized cobalt particles and powder, an atomizing method in which molten cobalt is dispersed in gas or water to obtain a fine powder, or cobalt is volatilized as disclosed in Patent Document 1, and a gas phase is obtained. A dry method such as a CVD method is known in which cobalt powder is obtained by reduction in the inside.

Further, as a method for producing cobalt powder by a wet process, a method using a reducing agent as shown in Patent Document 2 or a cobalt solution sprayed in a reducing atmosphere at a high temperature as shown in Patent Document 3 Thus, there is a spray pyrolysis method for obtaining cobalt powder by a thermal decomposition reaction.
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 materials such as the battery materials described above.

Further, in the method of growing by using cobalt powder as a seed crystal as shown in Patent Document 4, the seed crystal and the grown cobalt powder are re-dissolved in order to react in an acidic solution having a pH of 4 or less. There was a problem that the actual yield was lowered.

Furthermore, in the method in which a sodium hydroxide aqueous solution is added to the raw material cobalt sulfate solution and hydrogen reduction is performed, if the pH rises without being able to maintain pH 4, cobalt hydroxide is generated and the reduction reaction proceeds. As a result, there was a problem that the efficiency in the reduction reaction was reduced.

On the other hand, as shown in Non-Patent Document 1, a method of obtaining cobalt powder by supplying hydrogen gas to a cobalt sulfate ammine complex solution in which cobalt is in the form of an ammonia complex to reduce cobalt ions in the complex solution. Industrially inexpensive and useful.
However, even in this method, since particles are generated and grown from an aqueous solution by a wet reaction, a large number of crystal nuclei are generated non-uniformly and the growth is hindered in the same manner as each of the prior arts described above. There is. In other words, it is indispensable to control the number of derived crystal nuclei within an appropriate range for efficient growth.
Therefore, as described above, a method is generally used in which a reducing agent is supplied to a slurry in which a small amount of fine crystals called seed crystals coexist and a target product is grown on the surface of the seed crystals to obtain a powder having a predetermined particle size. .

The seed crystals added in the above are often used after being subjected to a treatment such as pulverizing a part of the product repeatedly. However, it takes time and effort for processing, and the yield decreases as much as it is repeated. Furthermore, there has been a problem that the optimum grain size and properties of the seed crystal cannot always be obtained simply by pulverization.
That is, a method for stably obtaining a seed crystal used for crystal growth has been demanded.

JP 2005-505695 A JP 2010-242143 A Japanese Patent No. 4286220 JP-A-57-54207

Under such circumstances, the present invention provides a production method for efficiently obtaining cobalt powder by a method for increasing the reduction reaction efficiency in producing cobalt powder from a solution containing a cobalt ammine sulfate complex.

The first invention of the present invention that solves such problems is to add a solution containing a cobalt sulfate ammine complex by adding ammonia, an ammonia compound solution, or both ammonia and an ammonia compound solution to a cobalt sulfate solution. A complexing step to be obtained, a mixing step in which a solid is added to the solution containing the cobalt ammine sulfate complex obtained in the complexing step to form a mixed slurry, and the mixed slurry obtained in the mixing step are placed in a reaction vessel. A reduction / precipitation step of obtaining a cobalt powder slurry containing cobalt precipitates in which hydrogen gas is blown into the reaction vessel to reduce cobalt contained in the mixed slurry and the cobalt component is deposited on the solid surface as cobalt powder; Next, the obtained cobalt powder slurry is subjected to a solid-liquid separation process to obtain a cobalt precipitate and a post-reduction liquid in order. A method for producing a seed crystal of cobalt powder to.

In the second invention of the present invention, the solid material in the first invention is made of a material insoluble or hardly soluble in the solution containing the cobalt ammine sulfate complex, and the average particle size thereof is 0.1 μm or more and 5 μm or less. It is the manufacturing method of the seed crystal of cobalt powder characterized by these.

According to a third aspect of the present invention, there is provided a method for producing a seed crystal 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. It is.

The fourth invention of the present invention is a method for producing a seed crystal of cobalt powder, characterized in that the solid material in the first to third inventions is nickel powder.

In the fifth invention of the present invention, the solid-liquid separation step in the first to fourth inventions comprises a solid-liquid separation process for separating the cobalt deposit and the post-reduction liquid from the cobalt powder slurry, and the obtained cobalt deposit. A seed of cobalt powder characterized by having a solids separation treatment for separating the added solids and cobalt powder deposited on the surface of the solids, and forming the post-reduction liquid and solids and cobalt powders It is a manufacturing method of a crystal.

According to the present invention, when producing a cobalt powder by reducing a cobalt sulfate ammine complex solution with hydrogen gas, a seed of an appropriate size is added to the cobalt sulfate ammine complex solution as a seed crystal to form the cobalt powder. Crystals can be obtained efficiently.

It is a manufacturing flow figure of the manufacturing method of cobalt powder concerning the present invention.

The present invention is a method for efficiently producing a seed crystal to be added when producing cobalt powder by blowing hydrogen gas into a cobalt sulfate ammine complex solution.

Hereinafter, the manufacturing method of the cobalt powder of this invention is demonstrated with reference to the manufacturing flowchart shown in FIG. In this invention, cobalt powder is obtained by passing the cobalt sulfate solution used as an original liquid through a complexing process, a mixing process, a reduction / precipitation process, and a solid-liquid separation process.
In addition, the reduction rate as used in the field of this invention was defined by the ratio which remove | divided the weight (g) of the obtained cobalt powder by the cobalt substance amount (g / L) contained in the supplied cobalt sulfate solution (L).

[Complexing process]
The cobalt sulfate solution that can be used in the present invention is not particularly limited, but is a kind selected from cobalt and cobalt-containing mixed sulfide, crude cobalt sulfate, cobalt oxide, cobalt hydroxide, cobalt carbonate, cobalt powder, and the like, Alternatively, a cobalt leaching solution obtained by leaching and dissolving a cobalt-containing material such as an industrial intermediate composed of a plurality of mixtures with sulfuric acid or ammonia can be used. In addition, industrially, the cobalt leachate generally contains various impurities, and the leachate described above is contained in the leachate by performing a liquid purification process such as solvent extraction, ion exchange, and neutralization. In general, it is used after removing the impurity element.

Next, aqueous ammonia or ammonium sulfate is added to the cobalt leaching solution to obtain a cobalt sulfate ammine complex solution.
The ammonium sulfate concentration in the solution is preferably in the range of 10 to 500 g / L. If the concentration is 500 g / L or more, the solubility may be exceeded and crystals may be deposited, which may cause operational troubles. Moreover, since ammonium sulfate newly produces | generates by reaction by the density | concentration of less than 10 g / L, industrially less than 10 g / L is difficult.
The cobalt concentration in the cobalt sulfate ammine complex solution is 75 g / L or less. This is because, when adding and reacting a solid in the subsequent step, if the cobalt concentration in the cobalt sulfate ammine complex solution is too high, the reaction field is insufficient and the reduction rate is lowered.

[Mixing process]
In this step, a solid substance that serves as a base material for precipitation is added to the cobalt sulfate ammine complex solution prepared above.
The solid substance to be added is not particularly limited as long as it is insoluble in the cobalt sulfate ammine complex solution, the ammonium sulfate aqueous solution, or the alkali solution, or is hardly soluble and has low solubility.

Specifically, it is preferable to use nickel powder.
When cobalt powder is used as a solid substance, it is the same as cobalt precipitate, so it is not necessary to peel them off in the subsequent process and is optimal for use as a seed crystal, but industrially fine cobalt powder is inexpensive and stable. It is difficult to obtain.

Iron powder has the advantage of being inexpensive and easily available, but has the disadvantage of being easily dissolved in an acidic solution and difficult to form crystal nuclei. Also, the dissolved iron ion is not suitable because it causes new contamination.
Also, in the method of depositing cobalt on a hardly soluble or insoluble solid as in the present invention, a method of depositing cobalt using a seed crystal that has been conventionally used to produce a product together with the seed crystal. Unlike the process, the effect of redissolving is negligibly avoided and there is no need to repeat a part of the product, so that the cobalt complex ions contained in the ammine complex solution can be reduced almost completely in terms of the process quantity balance. There are features that can be done.

In addition, it is preferable that the solid has a gentle shape so that the precipitated cobalt powder can be effectively separated, and the amount added is an amount that is equal to or more than the amount of cobalt present in the solution, as described above. More specifically, when nickel powder is used as a solid material, 75 g / L or more must be added.

[Reduction / precipitation process]
Next, the slurry formed by adding nickel powder in the mixing step is charged into a reaction vessel of a pressure vessel, a reducing agent such as hydrogen gas is blown into the reaction vessel, and cobalt complex ions in the slurry are injected. Reduce to deposit cobalt on the surface of the solid.

The temperature of the mixed slurry at this time, that is, the reaction temperature is preferably in the range of 150 to 200 ° C. If it is less than 150 degreeC, reduction | restoration efficiency will fall, and even if it is 200 degreeC or more, there is no influence on reaction, rather, loss, such as a heat energy, increases.

In addition, the pressure in the gas phase, which is a gap with the solution in the reaction vessel, is preferably maintained in the range of 1.0 to 4.0 MPa by supplying hydrogen gas. When the pressure is less than 1.0 MPa, the reaction efficiency is lowered because the amount of gas mixed into the solution from the gas phase is small. On the other hand, even if the pressure exceeds 4.0 MPa, there is no influence such as that the reaction is promoted. Rather, the loss of hydrogen gas only increases, which is not advantageous.
The hydrogen gas may be blown into the gas phase portion in the reaction tank or directly into the slurry.

[Solid-liquid separation process]
The solid matter having cobalt precipitates on the surface obtained in the reduction / precipitation step is taken out from the pressure vessel together with the post-reduction liquid in the pressure vessel, and solid-liquid separated from the post-reduction solution.
This solid-liquid separation may be any method such as a method using Nutsche and a filter bottle, a method using a centrifuge, or a method using a filter press.

Next, when using a substance other than cobalt as the solid, an operation of separating the solid and the cobalt deposit on the surface may be performed.
The method of specifically separating can be appropriately performed by giving an impact to the solid and the cobalt precipitate.

In addition, if the size of the cobalt precipitate containing the solid matter and the cobalt precipitate after being separated from the solid matter is too small for the use to be used as a seed crystal, repeat the above mixing step again to precipitate cobalt. The size of the object can be increased.
Moreover, the solid substance collect | recovered here can be repeatedly used for the said mixing process again.
The solution after reduction can be regenerated to ammonia as it is or by treatment such as heating / distillation and repeatedly used as a complexing agent in the complexing step.

The Example which produces | generates the seed crystal for obtaining the cobalt powder of this invention below is demonstrated.
The average particle size was measured using a commercially available laser diffraction / scattering particle size distribution measuring device (Microtrack).

A solution containing a cobalt sulfate ammine complex was obtained by adding 191 ml of 25% aqueous ammonia to 330 g of cobalt sulfate and 75 g of cobalt corresponding to 75 g of cobalt and dissolving the solution, and adjusting the total liquid volume to 1000 ml.
To this solution, 75 g of nickel powder having a particle size of 1 μm serving as a precipitation matrix was added to obtain a mixed slurry.

Next, after charging the above mixed slurry into an inner can of an autoclave having a capacity of 3 liters, with stirring and raising the temperature to 185 ° C., hydrogen gas was blown into the mixed slurry, and the inner can of the autoclave Hydrogen gas was supplied so as to maintain the internal pressure at 3.5 MPa. After 60 minutes had passed since the supply of hydrogen gas, the supply of hydrogen gas was stopped and the inner cylinder can was cooled.

After cooling to room temperature, the mixed slurry in the inner cylinder can was filtered to take out an insoluble solid having a cobalt precipitate formed on the surface, and then solid-liquid separation was performed by suction filtration using a filter bottle and Nutsche.
The reduction reaction rate of cobalt at this time was 99%.

(Comparative Example 1)
A solution containing 75 g of cobalt, 330 g of ammonium sulfate, and 191 ml of 25% aqueous ammonia was obtained. To this, 3.73 g of polyacrylic acid having a concentration of 40 wt% was added as a dispersant in place of the solid of the seed crystal of the present invention. The liquid volume was adjusted to 1000 ml to prepare a solution containing a cobalt sulfate ammine complex.
To this solution, 75 g of cobalt powder as a precipitation matrix was added to prepare a mixed slurry.

After the prepared mixed slurry was charged into the inner cylinder can of the same autoclave as in Example 1, the hydrogen gas was blown in a state where the temperature was raised and maintained at 185 ° C. while stirring, and the pressure in the inner cylinder can of the autoclave was changed. Hydrogen gas was supplied so as to maintain the pressure at 3.5 MPa.
After 60 minutes had passed since the supply of hydrogen gas, the supply of hydrogen gas was stopped and the inner cylinder can was cooled.

After cooling to room temperature, the mixed slurry in the inner cylinder can was filtered to take out an insoluble solid with a cobalt precipitate formed on the surface, and then solid-liquid separation was performed by suction filtration using a filter bottle and Nutsche. At this time, the cobalt reduction reaction rate was 72%, which was not as efficient as the examples of the present invention.

(Comparative Example 2)
A solution containing cobalt sulfate ammine complex was prepared by adjusting 191 ml of 25% aqueous ammonia to a solution containing 330 g of ammonium sulfate in a cobalt sulfate solution of 75 g of cobalt to a total liquid volume of 1000 ml.
To this solution, 75 g of commercially available iron powder having an average particle diameter of 1 μm was added as a solid substance dissolved in this solution to prepare a mixed slurry.

After the prepared mixed slurry was charged into the inner can of the autoclave used in Example 1, the temperature was raised to 185 ° C. while being stirred, and hydrogen gas was blown into the autoclave so that the pressure in the inner can of the autoclave was increased. Hydrogen gas was supplied so as to maintain the pressure at 3.5 MPa. After 60 minutes had passed since the supply of hydrogen gas, the supply of hydrogen gas was stopped and the inner cylinder can was cooled.

After cooling to room temperature, the mixed slurry in the inner cylinder can was filtered to take out iron powder with cobalt precipitates formed on the surface, and then solid-liquid separation was performed by suction filtration using a filter bottle and Nutsche.

Although the cobalt reduction reaction rate according to Comparative Example 2 is 76%, which is higher than in the case of using a conventional dispersant, the effect as in the examples of the present invention cannot be obtained even when a solid substance that is easily dissolved is added. I understood it.

Claims

A complexing step of adding ammonia, an ammonia compound solution, or both of the ammonia and ammonia compound solution to a cobalt sulfate solution to obtain a solution containing a cobalt sulfate ammine complex;
A mixing step in which a solid is added to the solution containing the cobalt ammine sulfate complex obtained in the complexing step to form a mixed slurry;
The mixed slurry obtained in the mixing step is charged into a reaction vessel, and hydrogen gas is blown into the reaction vessel to reduce cobalt contained in the mixed slurry, whereby a cobalt precipitate is deposited on the solid surface as cobalt powder. Reduction / precipitation step to obtain a cobalt powder slurry containing
Then, the obtained cobalt powder slurry is subjected to a solid-liquid separation process to obtain a cobalt precipitate and a post-reduction liquid in order.
The solid material is made of a material that is insoluble or hardly soluble in a solution containing the cobalt sulfate ammine complex,
The said average particle diameter is 0.1 micrometer or more and 5 micrometers or less, The manufacturing method of the seed crystal | crystallization of the cobalt powder of Claim 1 characterized by the above-mentioned.
The method for producing a seed crystal of cobalt powder according to claim 1 or 2, wherein a cobalt concentration in the solution containing the cobalt sulfate ammine complex is 75 g / L or less.
The method for producing a seed crystal of cobalt powder according to any one of claims 1 to 3, wherein the solid matter is nickel powder.
The solid-liquid separation step is a solid-liquid separation process for separating a cobalt deposit and a post-reduction liquid from a cobalt powder slurry;
A solid separation process for separating the obtained cobalt precipitate into the added solid and the cobalt powder deposited on the surface of the solid, and forming the post-reduction liquid, the solid and cobalt powder. The method for producing a seed crystal of cobalt powder according to any one of claims 1 to 4.