Method for purifying zinc sulfate aqueous solution to remove nickel, cobalt and germanium

Abstract

The invention relates to a method for purifying a zinc sulfate aqueous solution. In a supernatant, a zinc powder is used to remove copper and cadmium. At a temperature of 80 to 95 DEG C, the zinc powder and a copper antimony activator are added to purify to remove cobalt, nickel and germanium. According to the cobalt concentration of the solution, the copper antimony activator, the zinc powder anda small amount of sulfuric acid or electrolytic waste liquid are added. For a section of waste solution after copper and cadmium removal, containing 2-120 mg / l of cobalt, 0.02-0.3 mg / l of germanium,0.02-4 mg / l of nickel, and 5-120 mg / l of cadmium, the purifying effect of the waste solution containing 0.1 mg / l of cobalt, 0.02 mg / l of germanium, and 0.1 mg / l of nickel can be realized after 90-150minutes. Various zinc powders are used to realize deep purification of the solution. The method is suitable for a purification system of an electrolytic zinc plant.

Description

technical field [0001] The invention belongs to the field of metallurgy of non-ferrous metals, and mainly relates to a method for purifying and removing nickel, cobalt and germanium by hydrometallurgy, in particular to a method for purifying and removing nickel, cobalt and germanium after a section of copper and cadmium removal The method, aiming at the deficiency of traditional purification and removal of cobalt, has been improved. Background technique [0002] The classic wet electrolytic production of zinc metal consists of the following process: a first step of leaching, in which the oxides of zinc containing impurities are leached with sulfuric acid recovered from electrolysis. [0003] The end point of the leaching solution is around pH 5.4, so that an appropriate amount of Fe 3+ Co-precipitate with arsenic, iron, germanium and some other elements, and by such a method, a neutral zinc sulfate leaching solution containing impurities is obtained. [0004] However, the ...

AI Technical Summary

Problems solved by technology

The second type is to add other metal elements to the zinc powder to improve the activity or replacement capacity of the zinc powder, but the law of cobalt removal has not been fully grasped so far, which leads to the adaptability of purification to raw materials in the production practice of zinc hydrometallurgy Poor, high consumption of zinc powder

The second-stage temperature is 75°C, but the cadmium-cobalt slag produced by this method is easy to oxidize. The characteristic of this method is that cobalt can be removed without adding copper and only a small amount of antimony, but the cadmium concentration required for cobalt removal is relatively high, making a large amount of Cadmium is cycled in the process

[0026] In 2000, Russian patent 2186131C2 proposed the use of zinc alloy zinc powder containing 0.6-0.9% lead and 0.003-0.5% iron to remove cobalt and nickel, and achieved the effect of reducing zinc powder, but obviously the iron in the solution will increase

The inventor believes that when antimony oxide and antimony potassium tartrate are added in a large amount, antimony may exceed the antimony content control standard of the electrolytic purification solution

[0035] 2. Antimony salts use different compounds, mainly antimony potassium tartrate and antimony oxide, but no patents have been found to compare the two. Most of the antimony compounds used in patents are antimony oxide, and the rest are antimony potassium tartrate. There is only one article The patent (Canadian patent 1122229) proposes the use of pentavalent antimony salts to remove cobalt

However, it is obvious that since this first-stage purification slag contains almost all impurity elements, the treatment process is relatively difficult, especially the need for secondary cobalt removal

[0042] 6. In terms of equipment, reactors with special structures are used to improve the efficiency of cobalt removal and reduce the consumption of zinc powder. However, these special tank types are inconvenient to use and most of them have not been applied in industry; or use high pressure to increase the rate of cobalt removal. Obviously, the complexity of high-pressure equipment limit its industrial application

[0062] In 2018, Toni Karlsson et al. [9] studied the kinetics of the cobalt removal process and the morphology of the purified product in an attempt to reveal the form of cobalt in the product, but the research results showed that only cobalt hydroxide was found in the slag, not cobalt. Discovery of the metal cobalt

[0064] 1. There is a lack of adjustment methods for the addition of zinc powder and copper antimony activator when the solution of different components, especially when the cobalt content changes,

[0065] 2. Lack of control of the amount of acid added in the process of acid adjustment and detection methods for related parameters in the solution

[0066] 3. Lack of targeted preventive measures based on the mechanism of cobalt redissolution

[0067] 4. Lack of reliable cobalt replacement mechanism theory

[0068] 5. There is a lack of research on the difference between the two commonly used antimony compounds as activators for purification and removal of cobalt, and it is not easy to adjust according to production changes in production practice

[0069] The existence of these problems leads to the inability to quickly adjust when the solution composition changes drastically during the production process, resulting in fluctuations in the impurity concentration of the purified solution, which in turn affects the normal operation of electrolysis

Obviously, the existence of this problem is the result of the above-mentioned complex reasons, and these intertwined factors all have an adverse effect on the cobalt removal process

[0070] The change of cobalt concentration in production also makes this problem more complicated. Obviously, relying on a single solution cannot solve this problem. The unclear mechanism of cobalt removal makes these improvements more difficult. The main difficulties encountered in purification in production

Images