JPH0696455B2 - Method for producing high-purity cobalt sulfate - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a method for producing high-purity cobalt sulfate which is useful for building a cobalt plating bath, replenishing, magnetic material, electronic material and the like.

[Prior Art] Conventionally, as a method for producing high-purity cobalt sulfate, (a) a method in which iron powder and sulfide are allowed to act on a solution of metallic cobalt or cobalt powder dissolved in sulfuric acid to precipitate impurities.

B) A method in which sodium sulfide or sodium hydrosulfide is added to a solution of metallic cobalt or cobalt powder dissolved in sulfuric acid to precipitate impurities.

C) A method of removing impurities by pouring a solvent has been put into practical use.

However, the high-purity cobalt sulfate obtained by the above methods (a), (b), and (c) has a drawback that it is difficult to remove impurities up to an extremely low concentration, especially nickel, and the production efficiency is poor.

[Problems to be solved by the invention]

An object of the present invention is to solve the above problems and provide a method for efficiently producing a highly pure cobalt sulfate aqueous solution or a crystal.

[Means for solving problems]

In order to achieve this object, the inventors of the present application added cobalt powder to an aqueous solution of cobalt sulfate containing impurities, and added sodium hydrosulfide, sodium sulfide or hydrogen sulfide to the reaction to cause a reaction. The inventors have found that nickel, iron, copper, etc., which are present as impurities, can be precipitated and removed to an extremely low concentration by adding a small amount of sodium hypochlorite or hydrogen peroxide to the method of the present invention.

That is, the method of the present invention uses, for example, 0.03 to 0.1 g of nickel and 0.005 to 0.0 g of iron as impurities in the cobalt sulfate aqueous solution 1.
1 to 10 g of cobalt fine powder is added per 1 of the above aqueous solution containing 8 g and pH of 2 to 5 and sodium hydrosulfide, sodium sulfide or hydrogen sulfide is added to 2 to 10 per 1 of the above aqueous solution with stirring.
Add g and react with stirring.

Nickel and copper contained as impurities in this process are precipitated and removed from the cobalt sulfate aqueous solution. Next, the above aqueous solution is suctioned and the above aqueous solution 1 is stirred while stirring the solution.
For example, 5 to 20 ml of sodium hypochlorite or hydrogen peroxide solution is added to separate the formed precipitate containing impurities such as iron and manganese.

In the method of the present invention, the aqueous solution of cobalt sulfate can be produced, for example, by dissolving electric cobalt in sulfuric acid or electrolytically dissolving it, but after removing impurities, it is crystallized or electric cobalt is electrowinned. From
It is advantageous to keep the cobalt sulfate concentration relatively high, and the method of the present invention can be applied when the cobalt concentration of the cobalt sulfate aqueous solution is 50 g / l or more. When the cobalt concentration is lower than this, the actual yield of cobalt is lowered, which is disadvantageous.

Nickel 0.03 ~ 0.1g / l of impurities in the above aqueous solution, iron 0.005
~ 0.08g / l comes from electric cobalt, and the cobalt powder to be added is obtained by thermal decomposition of oxalate or hydrogen reduction of carbonate or hydroxide.
It is preferably 200 mesh (0.074 mm) under. The amount of cobalt powder added is 1 to 10 g per 1 of the above aqueous solution.
The reason is that if the amount is less than 1 g, the effect of the addition is not sufficient, and even if the amount exceeds 10 g, there is no difference with the result of 10 g or less.

Sodium hydrosulfide is added to the above aqueous solution containing cobalt powder,
Adding 2 to 10 g / l of one or more kinds of sodium sulfide or hydrogen sulfide is an impurity contained in the above aqueous solution (nickel,
(Copper) is a preferable addition amount for separating to an extremely low concentration. If it is less than 2 g / l, a sufficient effect cannot be obtained and 10 g / l
If it is added in excess, the removal efficiency will no longer be improved, and the coprecipitation amount of cobalt will also increase, only degrading the yield of cobalt. At this time, if the reaction is performed while keeping the liquid temperature at 50 ° C or higher,
The reaction time can be shortened. It takes 30 minutes or longer at 50 ° C or higher to reach equilibrium. Sodium hypochlorite or a hydrogen peroxide solution was added to remove impurities such as iron and manganese, and the like, and the cobalt sulfate aqueous solution contained 0.
Although it is contained in an amount of about 04 g / l, it can be relatively easily lowered to 0.005 g / l or less by re-dissolving and re-crystallizing operations after crystallization by evaporation and concentration.

[Action]

In the method of the present invention, the purpose of adding cobalt powder to the cobalt sulfate aqueous solution is to lower the redox potential of the cobalt sulfate aqueous solution and to make a catalytic action that facilitates the separation of nickel as impurities as sulfides. .

Next, the addition of sodium hydrosulfide, sodium sulfide, or hydrogen sulfide to the above aqueous solution is intended to separate nickel, copper, etc. contained in the aqueous solution from the above aqueous solution as sulfides, but the addition amount is The amount that is significantly higher than the amount required to sulfurize the impurities contained in the above aqueous solution (0.06 to 0.13 g / l) is significantly exceeded by coprecipitating some of the cobalt in the above aqueous solution with the impurities. This is because an attempt is made to obtain a cobalt sulfate aqueous solution having an extremely low concentration of impurities.

Subsequently, a small amount of sodium hypochlorite or hydrogen peroxide solution is added for the purpose of oxidizing and removing iron and manganese contained in the aqueous solution.

〔Example〕

Example 1 5 l of cobalt sulfate aqueous solution having a cobalt concentration of 127 g / l and a pH of 3.5
Was taken in a beaker, kept at 60 ° C. in a constant temperature bath, and 25 g of cobalt powder obtained by thermally decomposing cobalt oxalate was added to the above aqueous solution while stirring. Next, 200 cc of an aqueous solution of sodium hydrosulfide adjusted to 200 g / l was added to the above aqueous solution of cobalt sulfate while stirring and reacted for 30 minutes while stirring. After this aqueous solution was suction-separated, 5 cc of sodium hypochlorite (effective chlorine 12%) was added to the solution, and the mixture was reacted for 30 minutes while stirring. Table 1 shows the analysis results of crystals obtained by immersing the beaker containing the above-mentioned aqueous solution in a reaction-terminated liquid in which the generated precipitate was separated by suction and a constant temperature bath, and evaporating, concentrating and cooling.

Example 2 Table 2 shows the results of an implementation test conducted under the same conditions as in Example 1 on an aqueous cobalt sulfate solution having a cobalt concentration of 78 g / l and a pH of 3.5.

Example 3 The addition amount of starting solution and cobalt powder, temperature, etc. were the same as in Example 1, and the addition amount of sodium hydrosulfide adjusted to 200 g / l was 100 cc.
Table 3 shows the results of (1/2 of Example 1) and the same operations as in Example 1 except for the above.

Example 4 The result of performing the same procedure as in Example 1 except that 200 cc of the starting solution and the amount of cobalt powder added, the temperature, etc. were the same as those in Example 1, 200 cc of sodium sulfide was adjusted to 200 g / l, and the other operations were performed The fourth
Shown in the table.

Example 5 The starting solution and the amount of cobalt powder added, the temperature, etc. were the same as in Example 1, and the same procedure was carried out for the times when hydrogen sulfide was blown through the glass tube. The blowing amount was 26 normal l in 60 minutes, and the operation after the same procedure as in Example 1 was carried out. The results are shown in Table 5.

(Effect of the invention) The cobalt sulfate aqueous solution produced according to the method of the present invention has a cobalt concentration of 60 to 120 g / l, nickel, iron, and copper contents of less than 0.002 g / l, and the actual yield of cobalt is 90. % Or more, and the cobalt sulfate crystals obtained by evaporating and concentrating the above cobalt sulfate aqueous solution and cooling are cobalt 20.0 to 20.6%,
Nickel is less than 0.0002%, iron is less than 0.0002%, copper is less than 0.0001%, and zinc is less than 0.001%. Sodium in the cobalt sulfate aqueous solution by recrystallization operation can be relatively easily less than 0.005 g / l, cobalt sulfate crystals by the conventional method nickel 0.01 ~ 0.05%, iron 0.0005 ~ 0.0005%,
Compared with containing 0.0003 to 0.0005% copper, the present invention is suitable as a method for producing high-purity cobalt sulfate,
It is extremely useful as a bath for cobalt plating baths, as a replenisher, as a magnetic material, and as an electronic material.

Claims (1)

[Claims] 1. A cobalt sulfate aqueous solution containing 50 g / l or more of cobalt, to which 1 to 10 g of cobalt powder per 1 aqueous solution is added, and then one or more of sodium hydrosulfide, sodium sulfide, and hydrogen sulfide are added to the aqueous solution. 2 to 1 per the above aqueous solution
After adding 10 g and reacting with stirring, a small amount of sodium hypochlorite or hydrogen peroxide is added to the liquid from which the formed precipitate has been separated, and the formed precipitate is separated. Manufacturing method.