JP2017014593A - Cobalt powder production method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a cobalt powder production method which can obtain high reaction efficiency by controlling the amount of added seed crystal when producing a cobalt powder from a solution containing a cobalt sulfate ammine complex.SOLUTION: In a cobalt powder production method, a cobalt powder is produced by sequentially performing: a mixing step of adding, as a seed crystal, ground cobalt, in an amount of 1.5 times or more and 3.0 times or less to the amount of cobalt contained in a solution containing a cobalt sulfate ammine complex, to the solution and then adding a dispersing agent in an amount of 1.5% to 3.0% by weight of the added seed crystal so as to form mixed slurry; and a reduction and precipitation step of, after charging the mixed slurry into a reaction vessel, blowing hydrogen gas into the mixed slurry to reduce cobalt complex ions contained in the mixed slurry so as to form a cobalt precipitate on the surface of the seed crystal.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a method for producing cobalt powder having a high reaction efficiency when producing cobalt powder from a solution containing a cobalt sulfate ammine complex. In particular, the present invention relates to an intermediate product solution in a process generated from a wet cobalt smelting process. Applicable to processing.

As a method for producing a fine cobalt powder, an atomizing method in which molten cobalt is dispersed in gas or water to obtain a fine powder, or cobalt disclosed in Patent Document 1 is volatilized and reduced in a gas phase to thereby reduce cobalt. A dry method such as a CVD method for obtaining powder is known.
Moreover, as a method of producing cobalt powder by a wet process, a method of producing using a reducing agent disclosed in Patent Document 2 or a spraying of a cobalt solution in a reducing atmosphere at a high temperature disclosed in Patent Document 3 Thus, there is a spray pyrolysis method for obtaining cobalt powder by a pyrolysis reaction.

  However, these methods are expensive because they require expensive reagents and a large amount of energy.

On the other hand, as shown in Non-Patent Document 1, a method of supplying cobalt gas to a cobalt sulfate ammine complex solution to reduce cobalt ions in the complex solution to obtain cobalt powder is industrially inexpensive and useful. . However, in this method, there is a problem that the cobalt powder particles obtained are easily coarsened.
In particular, when generating and growing particles from an aqueous solution, a small amount of fine crystals called seed crystals coexist in a small amount, a reducing agent is supplied thereto, and seed crystals are grown to obtain a powder having a predetermined particle size. The method is used.

In this method, depending on the cobalt concentration in the aqueous solution to be used, the type of seed crystal, etc., high reaction efficiency cannot be obtained, and the yield decreases, leading to an increase in cost.
Generally, in such a case, it is possible to improve the reaction efficiency by reducing the seed crystal particle size and increasing the reaction field, but it takes time and effort to reduce the seed crystal particle size. In the case of using a seed crystal of a dissimilar metal, there is a problem that the purity of the product is lowered due to the seed crystal component remaining.

  Therefore, there has been a demand for a method having high reaction efficiency without using a dissimilar metal as a seed crystal and without using a seed crystal having a small particle size.

JP-A-2005-505695 Japanese Patent No. 5407495 Japanese Patent No. 4286220

“The Manufacture and properties of Metal powder produced by the gaseous reduction of aquatic solutions”, Powder metallurgy. 1/2 (1958), PP40-52.

  Under such circumstances, the present invention obtains high reaction efficiency by controlling the amount of seed crystals added when producing cobalt powder from a solution containing a cobalt sulfate ammine complex, and produces cobalt powder. A method is provided.

  In order to solve such a problem, the first invention of the present invention provides a solution containing a cobalt sulfate ammine complex at least 1.5 times the amount of cobalt contained in the starting solution as a seed crystal. A mixing step of adding cobalt powder in an amount of 0 times or less and then adding a dispersant of 1.5 wt% to 3.0 wt% of the added seed crystal to form a mixed slurry, and the mixed slurry in a reaction vessel Then, hydrogen gas is blown into the mixed slurry, and cobalt complex ions contained in the mixed slurry are reduced to form cobalt precipitates on the seed crystal surface. It is a manufacturing method of the cobalt powder characterized by producing powder.

  2nd invention of this invention is a manufacturing method of cobalt powder characterized by the ammonium sulfate density | concentration in the solution containing the cobalt sulfate ammine complex in 1st invention being the range of 10-500 g / L.

  A third invention of the present invention is a method for producing cobalt powder, wherein the temperature of the mixed slurry when hydrogen gas is blown in the reduction step of the first and second inventions is 150 to 200 ° C. .

  The fourth invention of the present invention is characterized in that the pressure in the gas phase part in the reaction tank when hydrogen gas is blown in the reduction process of the first to third inventions is in the range of 1.0 to 4.0 MPa. It is a manufacturing method of cobalt powder made into.

  According to the present invention, a cobalt powder can be produced with high reaction efficiency in a method of producing a cobalt powder by adding a dispersant to a cobalt ammine complex solution and performing hydrogen reduction under high temperature and pressure.

It is a manufacturing flow figure of the manufacturing method of cobalt powder concerning the present invention. 2 is an SEM image showing an appearance of cobalt powder generated in Example 1. FIG.

The high purity cobalt powder production method of the present invention uses a high pressure vessel such as an autoclave to add a seed crystal to a cobalt sulfate ammine complex solution, and performs a hydrogen reduction treatment with hydrogen at a high temperature and high pressure. Add 1.5 times or more and 10.0 times or less, preferably 1.5 times or more and 3.0 times or less, more preferably 2.0 times as much cobalt powder as the seed solution cobalt amount. It is a manufacturing method of cobalt powder characterized by manufacturing cobalt powder.
Hereinafter, the manufacturing method of the cobalt powder of this invention is demonstrated with reference to the manufacturing flowchart shown in FIG.

[Cobalt sulfate ammine complex solution]
The cobalt sulfate ammine complex solution used in the present invention is not particularly limited, but one or a mixture selected from cobalt and cobalt mixed sulfide, crude cobalt sulfate, cobalt oxide, cobalt hydroxide, cobalt carbonate, cobalt powder and the like. Cobalt leachate (solution containing cobalt) obtained by dissolving cobalt-containing materials such as industrial intermediates composed of sulfuric acid or ammonia, and subjecting it to liquid purification processes such as solvent extraction, ion exchange, and neutralization A solution obtained by removing the impurity elements in the solution and adding ammonia to form a cobalt ammine sulfate complex solution is suitable, and cobalt is contained in the form of cobalt complex ions.

[Mixing process]
In this step, seed crystals are added to the cobalt sulfate ammine complex solution prepared above, and a dispersant according to the amount of the added seed crystals is added to obtain a mixed slurry.
Cobalt powder is used for the seed crystal added here.
As the cobalt powder used for the seed crystal, a commercial product may be used, but it is more preferable to use a part of the product obtained by the production method of the present invention repeatedly.

The cobalt powder preferably has an average particle size of about 0.1 to 5 μm, and particularly preferably has a size of about 1 μm and a uniform particle size.
If it is too fine, the cobalt powder obtained by the reaction is too fine and difficult to handle, which is not preferable. On the other hand, if it is too large, there is a problem that it is easy to settle during stirring, and it becomes difficult to obtain uniform cobalt powder.

In order to keep the reaction efficiency high, the amount added is 1.5 times or more and 3.0 times or less, preferably 2.0 times the amount of cobalt contained in the original solution. Is preferred.
If the addition amount is less than 1.5 times, the number of seed crystals is insufficient and the reaction field decreases, so that high reaction efficiency cannot be obtained. Also. Even if it exceeds 3.0 times, the reaction efficiency is not improved, and the efficiency is not improved although it takes too much time and cost. On the contrary, the growth of cobalt powder obtained by too many seed crystals is insufficient and the particle size becomes small, so when using it as a product, problems such as handling and handling are likely to occur, In addition, it is not preferable because of problems in characteristics such as easy melting and oxidation.

  Furthermore, the amount of the dispersant added is more added by including the concentration in the range of 1.5 wt% or more and 3.0 wt% or less with respect to the seed crystal amount added to the cobalt sulfate ammine complex solution. This is desirable because the seed crystals are uniformly dispersed and the desired nickel powder is easily obtained.

The ammonium sulfate concentration in the solution is preferably in the range of 10 to 500 g / L.
If it is 500 g / L or more, the solubility is exceeded and crystals are deposited. The lower limit is difficult to achieve less than 10 g / L because ammonium sulfate is newly generated by the reaction.

[Reduction / precipitation process]
Next, the slurry added with seed crystals in the previous step is charged into a reaction vessel of a high pressure resistant high temperature vessel, and hydrogen gas is blown into the slurry stored in the reaction vessel, and cobalt complex ions in the slurry are added. To deposit cobalt on the contained seed crystals.

  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 efficiency will fall, and even if it is 200 degreeC or more, there is no influence on reaction, rather, since loss, such as a heat energy, increases, it is not suitable.

Furthermore, the pressure of the gas phase part in the reaction tank at the time of reaction (referring to the space part in the reaction tank remaining after storing the solution in the reaction tank) controls the supply amount of hydrogen gas to 1.0 to 4. It is preferable to maintain in the range of 0 MPa. If the pressure is less than 1.0 MPa, the reaction efficiency is lowered, which is not preferable. Moreover, even if it exceeds 4.0 Mpa, there is no influence on reaction efficiency and the loss of hydrogen gas increases.
In addition, blowing hydrogen gas into the mixed slurry can reduce cobalt complex ions in the slurry by blowing directly into the liquid in the reaction tank or blowing into the gas phase portion.

  By the reduction / precipitation treatment of the present invention, a cobalt precipitate is formed on the seed crystal, and the cobalt contained in the solution can be recovered and used repeatedly as a fine powdery cobalt precipitate.

  By preparing a seed crystal of fine powdery cobalt powder that can be used as a seed crystal as described above and repeating hydrogen reduction, particles having cobalt precipitates formed on the seed crystal surface are formed. Can be grown to produce high purity cobalt metal.

  Hereinafter, the present invention will be described with reference to examples.

[Mixing process]
A solution obtained by adding 465 g of ammonium sulfate to a cobalt sulfate solution containing 75 g of cobalt and further adding 191 ml of 25% ammonia water is used as a base solution. Add 150g, which is 2.0 times the amount of the liquid, and add 40wt% polyacrylic acid as a dispersant to the amount of 2.0% by weight of the seed crystal, and adjust the liquid volume to 1000ml. Thus, a mixed slurry containing a cobalt sulfate ammine complex containing seed crystals was produced.

[Reduction / precipitation process]
Next, the mixed slurry was charged into an inner cylinder can of the autoclave, sealed and heated to 185 ° C. while being stirred, and after being held, hydrogen gas was blown into the mixed slurry, Hydrogen gas was supplied from the cylinder so as to maintain the pressure in the inner cylinder can 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, the cobalt slurry collected by filtering the mixed slurry in the inner cylinder can was observed using an electron microscope (SEM), and it was confirmed that fine cobalt powder was produced as shown in FIG.
Further, the cobalt powder production reaction rate obtained by subtracting the amount of precipitated cobalt obtained by subtracting the amount of seed crystals from the amount of cobalt recovered by the amount of cobalt contained in the original solution, that is, the reduction production rate was 72%. .

(Comparative Example 1)
A base solution containing cobalt was prepared under the same conditions and method as in Example 1 above, 75 g of cobalt powder as a seed crystal was added 1.0 g of the original solution as a seed crystal, and the liquid volume was 1000 ml. Thus, a mixed slurry according to Comparative Example 1 was prepared. Next, after charging the prepared solution into the inner cylinder can of the autoclave, hydrogen gas was blown in the 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 to 3. Hydrogen gas was supplied to maintain the pressure at 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, when the solution in the inner cylinder can was filtered, fine cobalt powder was generated.
However, the production reaction rate of cobalt powder was only 36%, and the efficiency as high as Example 1 of the present invention was not obtained.

Claims (4)

To the solution containing the cobalt sulfate ammine complex, 1.5 times or more and 3.0 times or less of the amount of cobalt contained in the solution is added as a seed crystal, and then 1.5% of the added seed crystal amount is added. A mixing step of adding a weight percent to 3.0 weight percent dispersant to form a mixed slurry;
After charging the mixed slurry into a reaction tank, hydrogen gas is blown into the mixed slurry to reduce cobalt complex ions contained in the mixed slurry, thereby forming a cobalt precipitate on the seed crystal surface.・ Precipitation process
A method for producing cobalt powder, characterized in that cobalt powder is produced in order.   The method for producing cobalt powder according to claim 1, wherein the ammonium sulfate concentration in the solution containing the cobalt sulfate ammine complex is in the range of 10 to 500 g / L.   The method for producing cobalt powder according to claim 1 or 2, wherein the temperature of the mixed slurry when hydrogen gas is blown in the reduction step is 150 to 200 ° C.   Cobalt according to any one of claims 1 to 3, wherein the pressure in the gas phase portion in the reaction tank when hydrogen gas is blown in the reduction step is in the range of 1.0 to 4.0 MPa. Powder manufacturing method.