JP4538802B2 - Method for producing crude nickel sulfate - Google Patents

Description

The present invention relates to a method for producing crude nickel sulfate. More specifically, in the copper electrolysis process, in the method of removing nickel in the electrolyte as nickel sulfate by concentration cooling, the iron quality in the crude nickel sulfate is controlled by controlling the nickel concentration in the electrolyte. Regarding the method.

In order to remove impurities in the copper electrolyte, the electrolyte is first heated and concentrated, and then cooled to remove copper as copper sulfate. Next, impurities such as copper, arsenic, antimony, and bismuth are reduced and removed on the cathode side in an electrowinning process.
After the electrolytic collection, the solution is cooled to -15 to 0 ° C., and nickel in the solution is precipitated as crude nickel sulfate. Then, the nickel is removed from the solution by centrifugation, and the nickel concentration in the copper electrolyte is reduced. Balance.

Nickel moves from the scraps that are dissolved in the copper ore or in the copper smelting process to the copper anode and is brought into the copper electrolysis process.
Nickel in the anode is eluted into the electrolytic solution by an anodic reaction in the electrolytic purification process. The eluted nickel is removed out of the system as nickel sulfate to balance the nickel concentration in the electrolyte.

Iron behaves like nickel. That is, iron in the anode is eluted into the electrolytic solution by the anodic reaction, and is included in the crude nickel sulfate together with nickel and removed outside the system. The form at this time is considered to be iron sulfate.
On the other hand, as an open patent, for example, there is JP-A-2004-169158 (Patent Document 1), but iron is not conscious of impurities.
In Japanese Patent No. 3546911 (Patent Document 2), iron is removed by a solvent extraction method.
JP2004-169158 Patent No. 3546911

The object of the present invention is to provide a method for controlling the iron concentration in the crude nickel sulfate within a certain range by controlling the nickel concentration in the electrolytic solution.

In order to solve the above problems, the present invention
(1) In a method of removing nickel in an electrolytic solution as crude nickel sulfate by concentration cooling in a copper electrolysis process,
A method for producing crude nickel sulfate, which controls the nickel concentration in the electrolytic solution to 12 to 24 g / L, thereby suppressing the iron quality in the crude nickel sulfate to 0.5% or less.
I will provide a.

By implementing the present invention, the following effects can be obtained.
(1) The iron quality in crude nickel sulfate can be reduced by controlling the nickel concentration in the electrolytic solution.

The processing flow of the present invention will be described with reference to FIG.
The copper electrolyte is sent to the liquid purification process to remove impurities. Copper electrolyte usually contains 45-50 g / L of copper, 12-15 g / L of nickel, 0.75-1.00 g / L of iron, and 170-200 g / L of sulfuric acid. In the liquid purification process, the electrolytic solution is concentrated by heating.

The copper concentration at this time is 90 to 100 g / L, nickel is 24 to 30 g / L, iron is 1.5 to 2.0 g / L, and sulfuric acid is 340 to 400 g / L. By cooling the concentrated solution to 10 ° C., copper sulfate is precipitated. The copper sulfate, after solid-liquid separation, the product copper sulfate is separately purified.
After cooling, the liquid copper is 10 g / L, nickel is 24-30 g / L, and iron is 1.5-2.0 g / L.
Furthermore, copper, arsenic, antimony, and bismuth are removed by sending this solution to the electrowinning process.
The solution after electrolytic collection is copper 0.5 g / L, nickel 24 to 30 g / L, and iron 1.5 to 2.0 g / L.

Furthermore, nickel is deposited as crude nickel sulfate by cooling the solution after electrolytic collection to −15 to 0 ° C.
This crude nickel sulfate is called crude nickel sulfate because it contains a small amount of impurities.
Typical impurities are iron, aluminum, copper, and zinc. Part of the iron is considered to be mixed with the crude nickel sulfate in the form of iron sulfate.

In the present invention, the nickel concentration in the electrolytic solution is controlled, and the impurity quality in the crude nickel sulfate is controlled. That is, it has been found that the iron grade in the crude nickel sulfate is controlled by controlling the nickel concentration of the electrolytic solution within a certain range.

Details will be described with reference to FIGS.
FIG. 2 shows the transition of nickel and iron concentrations in the electrolytic solution and the iron quality in the crude nickel sulfate in actual operation. Although the iron concentration in electrolyte solution is between 0.75-1.0 g / L, it can confirm that the iron in rough | crude nickel sulfate is rising with the fall of the nickel concentration in electrolyte solution.
Further, it is desirable to keep the iron concentration in the electrolytic solution in the range of 0.75 to 1.0 g / L. This is to keep the iron grade in the crude nickel sulfate low.
FIG. 3 is a graph showing the relationship between the nickel concentration in the electrolytic solution and the iron quality in the crude nickel sulfate.
From FIG. 3, when the nickel concentration in the electrolytic solution decreases, the iron grade in the crude nickel sulfate increases at an accelerated rate, and when the nickel concentration in the electrolytic solution becomes 12 g / L or less, the iron grade in the crude nickel sulfate is 0. .5 or more can be confirmed.
It is estimated that when a liquid with a low nickel concentration is cooled, the nucleation of iron sulfate is promoted and iron sulfate is easily generated.

FIG. 4 shows the relationship between the nickel concentration in the electrolyte and the voltage of the electrolytic cell.
It can be confirmed that when the nickel concentration in the electrolytic solution is high, the energization resistance at the time of electrolytic refining is increased, and the voltage of the electrolytic cell is increased. Since the increase in the voltage of the electrolytic cell deteriorates the electrolysis power unit, the nickel concentration in the electrolytic solution is preferably low.

If the nickel concentration in the electrolytic solution is in the range of 12 to 24 g / L, the iron quality in the crude nickel sulfate can be controlled to 0.5% or less.
However, a high concentration of nickel serves as an energization resistance at the time of electrolytic refining, and causes a deterioration in the basic unit of electrolytic power. Therefore, the nickel concentration in the electrolytic solution is preferably in the range of 12 to 14 g / L.

Examples of methods for controlling the nickel concentration in the electrolyte include control of nickel quality in the anode and control of the amount of nickel sulfate removed outside the system.

As a result of analyzing actual operation data, a relationship as shown in FIG. 3 was found between the nickel concentration in the electrolyte and the quality of the crude nickel sulfate. The cooling temperature at this time is −15 to −10 ° C.

That is, as the nickel concentration in the electrolytic solution is lowered, the iron quality in the crude nickel sulfate increases. This is remarkable when the nickel concentration in the electrolytic solution is lower than 14 g / L, and when it is lower than 12 g / L, it can be confirmed that the iron grade in the crude nickel sulfate exceeds 0.5%.

The liquid purification process flow is shown. Changes in nickel concentration in copper electrolyte, iron concentration, and iron grade in crude nickel sulfate are shown. The relationship between the nickel concentration in the copper electrolyte and the iron quality in the crude nickel sulfate is shown. The relationship between the nickel concentration in the copper electrolyte and the electrolytic cell voltage is shown.

Claims (1)

In the copper electrolysis process, in the method of removing nickel in the electrolyte as nickel sulfate by concentrating and cooling,
A method for producing crude nickel sulfate, comprising controlling the nickel concentration in the electrolytic solution to 12 to 24 g / L, thereby suppressing the iron grade in the crude nickel sulfate to 0.5% or less.