JPS60121236A - Treatment of extracting solvent containing zinc as impurity - Google Patents

Abstract

PURPOSE:To reduce the amount of a solvent to be drawn and neutralized by removing zinc from a solvent drawn to remove zinc and by bringing the zinc-free solvent into contact with an aqueous soln. after back extraction to remove zinc from the aqueous soln. and to lower the concn. of zinc. CONSTITUTION:An aqueous soln. contg. Ni and Co is subjected to solvent extraction with tertiary amine as a solvent to obtain an aqueous soln. contg. Ni and an extracting solvent contg. Co. The extracting solvent is subjected to back extraction with water to obtain an aqueous soln. contg. Co and a solvent. Part of this solvent is drawn, and Zn contained in the solvent as an impurity is removed by neutralization to regenerate the Co extracting power of the solvent. The Zn-free solvent is then circulated to the solvent extraction stage together with the remaining solvent. At this time, the drawn solvent after the regeneration is brought into contact with the aqueous soln. contg. Co obtd. in the back extraction stage, and the solvent is circulated to the solvent extraction stage.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for treating a solvent comprising an 8th class amine containing zinc as an impurity.

A mixed sulfate solution of nickel and cobalt containing magnesium and zinc as the main impurities can be
Using an organic solvent having hydrogen atoms that can be exchanged with metal ions, such as Versatic acid (trade name of Shell Chemical Company), nickel and cobalt are transferred into the solvent, and then the nickel and cobalt in the extraction solvent are removed. By back-extracting with concentrated hydrochloric acid, a mixed chloride solution of nickel and cobalt that does not contain magnesium can be obtained. However, in solvent extraction using Versatic acid, only zinc is extracted into the solvent along with nickel and cobalt, and then back extracted, so only zinc is contained as an impurity. Solvent extraction is performed on such a solution using an 8th class amine such as tri-normal octylamine as a solvent, and cobalt is extracted as a complex salt of (11gH) 20o (Jl) in the extraction solvent to separate cobalt from nickel. Then, a cobalt-containing aqueous solution is obtained by back-extracting the nickel-containing aqueous solution and the cobalt extracted into the solvent with water. During this solvent extraction, the impurity zinc is converted into R24 of (RNH) Znal, which is more stable than cobalt. To form a complex salt, it is extracted into a solvent. During back-extraction, cobalt, which forms a more unstable complex salt, is preferentially extracted, but zinc is also contained in the solvent. It is back-extracted according to the concentration.

However, since the solvent is usually used in cycles between the extraction process and the back-extraction process, when treating a mixed chloride solution of nickel and cobalt containing zinc as an impurity, which is supplied to the extraction process, the zinc is removed from the system. Unless removed, the concentration of zinc in the solvent will gradually increase. Accordingly, the zinc concentration in the cobalt-containing aqueous solution obtained in the back extraction step also increases. When cobalt is electrolytically extracted from a cobalt-containing aqueous solution, zinc as an impurity precipitates in the electrodeposit and reduces the quality of the electrodeposited cobalt. Therefore, the zinc concentration in the aqueous solution is reduced to 0.001 g/ need to be reduced to below.

Therefore, the zinc concentration in the circulating solvent was reduced to 1 g/
In order not to exceed 1, a portion of the solvent is withdrawn in the process from back extraction to extraction, and after removing the zinc contained therein, this solvent is repeated in the extraction step.

Conventionally, to remove zinc contained in the extracted solvent, an alkali such as sodium hydroxide is added,
The following reaction is carried out to precipitate zinc as hydroxide and separate and remove it. (RNu)Zn0t+4NaOH-2RN-4-Zn
(OH) +4NaOj82 4 8 2 +2H2Q In that case, after regenerating the extraction capacity by treating the solvent thus obtained with a hydrochloric acid solution, (R3N+HO7-R2H-HG
/) The extraction process was repeated.

However, such a method involves an extremely uneconomical reaction (RN -Hol +NaOH-RIJ +NaO/
Since the dezincing reaction takes precedence over the dezincing reaction, if this reaction is carried out so that the zinc concentration in the cobalt-containing aqueous solution is 0.001 g/l or less, not only the amount of alkali used but also There is a problem in that the amount of hydrochloric acid solution required to regenerate the extraction ability of the solvent obtained by neutralization and removal becomes unnecessarily large. The amount of alkali needed to neutralize and remove the zinc and the amount of hydrochloric acid needed to subsequently regenerate the extractive capacity of the solvent can be minimized, in other words, The object of the present invention is to provide an economical and efficient method that can reduce the amount of solvent used for neutralization.

The present invention comprises a step of solvent extraction of cobalt from an aqueous solution containing nickel and cobalt using an 8th class amine as a solvent;
In order to remove the zinc in the solvent used by circulating the process of back-extracting cobalt from this extraction solvent with water, a portion is extracted from the solvent that is repeated from the back-extraction process to the solvent extraction process, and an alkali is added to this. The method consists in neutralizing and removing zinc, regenerating the cobalt extraction ability, and then contacting it with the cobalt-containing aqueous solution obtained in the back extraction step, and then repeating the solvent extraction step.

Next, an embodiment of the present invention will be described along with a conventional example according to the steps in the drawings.

A mixed sulfate solution of nickel and conolt containing impurities is purified by demanganization, iron removal, and copper removal, and then brought into contact with an organic solvent containing Versatic Acid F,
Next, a mixed chloride solution of nickel and co/(rut) obtained by contacting this organic solvent with concentrated hydrochloric acid was used as an aqueous solution containing N1.00.

The components and composition of this aqueous solution are shown in Table 1.

Table 1 Tri-normal octylamine (T
NOA) diluted with xylene at a volume ratio of 4:6 was used.

The N1, aO-containing aqueous solution is brought into contact with the solvent in three countercurrent stages at a rate of 100 cc/company to solvent extract cobalt,
Add 110 cc of warm water to the solvent used to extract this cobalt.
Cobalt was back-extracted from the solvent in three stages of countercurrent flow at a rate of /min.

During solvent extraction of cobalt, when the concentration of cobalt and zinc in the resulting solvent increases, cobalt is likely to be contained as an impurity in the nickel-containing aqueous phase (extraction residue) obtained by this solvent extraction. The concentrations of cobalt and zinc in this solvent are preferably maintained such that the cobalt concentration and zinc concentration X0.90 (atomic weight of cobalt/atomic weight of zinc) is 13 g/l or less.

A part of the solvent after back extraction was extracted, and the remaining part was repeated for solvent extraction of cobalt. A part of the extracted solvent was used to remove the zinc contained therein as a Zn (OH) cake using 50 g/l of aqueous sodium hydroxide solution, and the resulting Zn-free solvent was treated with 50 g of hydrochloric acid. After treatment with a solution to regenerate the extraction capacity, the regenerated solvent is directly used for cobalt solvent extraction, as shown in the conventional method shown in FIG. The method of the present invention shown in FIG. 2 was carried out by absorbing most of the zinc contained as an impurity in the extract and repeating the solvent extraction of cobalt as a Zn-containing solvent.

When Zn cleaning is performed by bringing this Zn-removed solvent into contact with the back-extraction aqueous solution, if the amount of regenerated solvent is smaller than the amount of the back-extraction aqueous solution, phase separation becomes difficult due to emulsification. Adjust the volume ratio between the amount of regenerated solvent and the amount of back-extracted aqueous solution by preparing a circulating solvent, etc.
: It is preferable to perform Zn cleaning so that the value becomes 15 or more.

Tests include solvent extraction of cobalt, Ni, and O.

The solvent to be brought into contact with the containing aqueous solution is 550 (conventional example), 60
0 (Example, same below), 660.770 cc/m
In addition, the amount of a part of the solvent to be extracted from the solvent after 00 back extraction is 24 (conventional example), 11 (example, the same applies hereinafter), 8 .5
．． It was carried out at a rate of 5 cc/-. Among these, in the test where the amount of extracted solvent was set at a rate of 5.5 cc/min, in order to maintain good phase separation, new solvent was added at a rate of 2.5 Cc/min in the contact step with the back extraction aqueous solution. Only used in circulation.

The solvent circulation process continues as described above, and after the system reaches equilibrium, the cobalt and zinc concentrations in the solvent and aqueous solution obtained, as well as the solvent extracted after reaching the equilibrium, are
Solid NaOHj! , converted to the amount of 1ONHOt and shown in Table 2.

According to the present invention, the solvent extracted to remove zinc is brought into contact with a back-extraction aqueous solution after removing zinc, and zinc is also removed from the back-extraction aqueous solution to reduce the zinc concentration in the back-extraction aqueous solution. However, in order to keep the zinc concentration in the back-extracted aqueous solution below the desired level, it is necessary to lower the zinc concentration in the circulating solvent as compared to the conventional method. As it is eliminated, the amount of solvent to be extracted can be reduced, and as is clear from Table 2,
Not only can the amount of alkali needed to remove the zinc contained as an impurity and the amount of hydrochloric acid needed to regenerate the extraction capacity significantly reduced, but the processing of the extraction solvent can also be improved. Can be done with light load.

[Brief explanation of the drawing]

FIG. 1 is a diagram of the extraction solvent circulation process according to the conventional method, and FIG. 2 is a diagram of the extraction solvent circulation process to which the method of the present invention is applied. Fan 1 figure Oni figure 2

Claims (1)

[Claims] (1) Perform solvent extraction from an aqueous solution containing nickel and cobalt using a tertiary amine as a solvent to obtain an aqueous solution containing nickel and an extraction solvent containing cobalt, and then back-extract the extraction solvent with water. A cobalt-containing aqueous solution and a solvent are obtained, and a part of this solvent is extracted, and zinc contained as an impurity is removed by neutralization treatment, and the cobalt extraction ability is regenerated. In the method of circulating the extracted solvent to the extraction process, the extracted solvent is recycled to the solvent extraction process after regenerating its cobalt extraction ability and being brought into contact with the cobalt-containing aqueous solution obtained in the back extraction process. A method for treating an extraction solvent containing zinc as an impurity.