JPS5943535B2 - Method for removing manganese from acidic solutions containing nickel and cobalt - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for removing manganese from acidic solutions of nickel and cobalt containing manganese as an impurity.

An acidic solution of nickel and cobalt containing manganese as an impurity is produced, for example, in the process of hydrometallurgical nickel refining by making a slurry of a mixture of nickel sulfide and cobalt sulfide, charging it into an autoclave, and extracting it by oxidation under pressure by blowing air into it. Obtainable.

Conventionally, as a method for removing manganese from a sulfuric acid solution of nickel and cobalt containing manganese as an impurity, chlorine gas is blown into the solution as an oxidizing agent, and the pH of the solution is adjusted by using a suitable neutralizing agent, For example, a method has been used in which manganese is precipitated and separated as manganese dioxide by adjusting it with nickel carbonate.

However, since this method deals with toxic chlorine gas, there are problems such as preservation of the working environment, corrosion of surrounding materials, and complicated work, as well as the use of expensive chemicals such as chlorine gas and neutralizing agents. There was a pharmaceutical problem of increased costs due to this.

In order to solve the above-mentioned problems, the present inventors conducted intensive research and arrived at the present invention by focusing on the following points.

That is, the acidic sulfuric acid solution of nickel and cobalt that has been conventionally used for demanganization includes, for example, the solution (1) obtained by pressurized oxidation extraction of the nickel sulfide and cobalt sulfide mixture, and metallic nickel or nickel matte. Electrolytic waste liquid containing impurities generated in the electrolytic refining process (
In order to remove cobalt from the anolyte (anolyte), the electrolytic waste solution is oxidized with chlorine gas and neutralized with nickel carbonate to precipitate most of the cobalt, and some of the nickel co-precipitates as a main component. takes the nickel-containing cobalt dispersion in the form of nickel hydroxide and cobalt hydroxide, which is further reduced to a slurry by the addition of sulfuric acid and sodium sulfite in order to recover nickel and cobalt. There was also a product (2) obtained by dissolving it, which was combined and subjected to demanganization treatment.

In other words, the latter solution (2) undergoes an inefficient process in which it undergoes oxidation and reduction steps and then undergoes a similar oxidation step in the next step.

Therefore, demanganization should be carried out more efficiently by adding the nickel-containing and cobalt precipitates obtained in the first oxidation step to obtain the solution (2) above to the solution (1) above. I focused on one thing.

That is, the present invention provides a method for precipitating and separating manganese as manganese dioxide from a sulfuric acid acidic solution containing nickel and cobalt as main components and manganese as an impurity, while maintaining the liquid temperature of the solution at 40 to 80°C, and While adjusting the pH of the solution to 0.8-1.8 with sulfuric acid, the solution was given a redox potential of 800-1100 mV (VS
.

The main components of the sulfuric acid acidic solution of nickel and cobalt to which the present invention is applied are nickel sulfate and cobalt sulfate, so adding oxidizing agents that contain metal elements other than nickel and cobalt may contaminate the solution. Although this is not preferable, as long as it can be separated and removed in a step after the solution is demanganized, such as iron, it may be contained within an appropriate range.

There are various oxidizing agents that satisfy these conditions, but the most preferable one is the electrolytic waste liquid (containing the impurities mentioned above).
It is a nickel-containing and cobalt precipitate whose main components are precipitated in the form of nickel hydroxide and cobalt hydroxide, which are obtained by subjecting the anolyte (anolyte) to oxidation with chlorine gas and neutralization with nickel carbonate.

This is because the material satisfies the above-mentioned conditions as an oxidizing agent, and in addition to containing almost no manganese, the material also contains high-grade nickel and cobalt. Although dissolution and recovery treatment is absolutely necessary,
This is because this treatment can be performed simultaneously with the demanganization treatment.

The quality of the nickel-containing and cobalt precipitate obtained by the above treatment is Ni: 20-40, Co: 5-20, Fe: 5.
~15, Mn: 0.1 or less.

The reactions in which manganese in a sulfuric acid solution is precipitated and separated as manganese dioxide by the oxidizing agents, nickel hydroxide and cobalt hydroxide, are as follows.

MnSO4+ 2Ni (OH)3+H2SO4→Mn
O2↓+2NiSo +4H20 MnSO4+2CO(OH)3+H2SO4-+MnO
□↓+2CO8O+4H20 In order to allow the above reaction to proceed at an actual operational level, the treatment solution should be prepared at a temperature of 40 to 80°C, a pH of 8 to 1.8, and an oxidation-reduction potential of 800 to 1100 mV (vs. S.

This is what is meant by C, E, hereinafter written as mV.

).

If any of these conditions is lower than the liquid temperature of 40°C, pH of 1.8 or higher, or redox potential of 800 mV or lower, the reaction will take time. , it is necessary to take measures to ensure the heat resistance and corrosion resistance of equipment materials such as pumps.

In addition, below p) lo, s, the reaction will not proceed sufficiently and the purpose of demanganization will not be achieved sufficiently. This is not a good idea as it will increase the amount used.

Furthermore, at a redox potential of 1100 mV or more, too much oxidizing agent is added, and unreacted nickel and cobalt increase in the precipitated manganese precipitate. Since treatment is required, any value outside the above range is economically unfavorable.

If the reaction proceeds under the above conditions, the manganese concentration in the liquid can be reduced to 0.01 in 1 to 4 hours continuously using a relatively small device.
g/2 or less.

Examples will be described below along with comparative examples.

In order to remove manganese from a sulfuric acid solution of nickel and cobalt containing manganese as an impurity, 38.10.9% by weight of each of Ni and Co SFe was added to the solution.
Approximately 150 g/A of nickel-containing and cobalt precipitates
The oxidizing agent as a slurry and concentrated sulfuric acid for pH adjustment are continuously supplied to a reaction tank equipped with a stirrer, and the overflow liquid is received in another reaction tank and concentrated as before. The demanganization reaction is completed by adjusting the pH with sulfuric acid.

The final reaction solution is also recovered from this reaction vessel by overflow.

Table 1 shows the composition and reaction conditions of the acidic solution tested on each side, and Table 2 shows the concentration of the final reaction solution and the quality of the demanganized product corresponding to each side in Table 1.

As is clear from Tables 1 and 2, the manganese concentrations in the final reaction solutions of Examples 1.2 and 3 obtained under preferable reaction conditions were all below 0.01 g/, indicating that manganese was sufficiently removed. has been done.

However, in Comparative Example 1, since the amount of nickel-containing and cobalt precipitates added was small, the oxidation-reduction potential did not increase sufficiently, and therefore the manganese concentration of the final solution was high.

On the other hand, in Comparative Example 2, the amount of nickel-containing and cobalt precipitates added was too large, so the final solution was sufficiently demanganized.
It can be seen that unreacted nickel-containing and cobalt precipitates are mixed into the demanganized material.

The above example describes the case where an oxidizing agent containing nickel and cobalt is applied to a sulfuric acid acidic solution containing nickel and cobalt, but the same conditions apply to an oxidizing agent containing only either nickel or cobalt. can be reacted with.

Similar conditions can also be applied to hydrochloric acid solutions containing nickel and cobalt.

As is clear from the above, the present invention does not require a toxic and difficult-to-handle oxidizing agent such as chlorine gas or a large amount of neutralizing agent, and in particular, the nickel-containing and cobalt sludge produced in the previous process is used as the oxidizing agent. In addition to the above, if the oxidizing agent is used, the process of reducing the oxidizing agent as described above becomes unnecessary, and the sulfuric acid used in the demanganization reaction is not only inexpensive but
Only H adjustment is required, and it is of extremely high economic value.

Claims (1)

[Claims] 1 In a method of precipitating and separating manganese as manganese dioxide from a sulfuric acid acidic solution containing nickel and cobalt as main components and manganese as an impurity, the temperature of the solution is maintained at 40 to 80°C, and the pH of the solution is The solution has a redox potential of 800-1100 mV (vs, s, c), adjusted to 0.8-1.8 with sulfuric acid.
. How to remove.