Method for extracting tellurium from tellurium copper slags

Abstract

The invention provides a method for extracting tellurium from tellurium copper slags. The method includes the following steps of (1) sulfating calcination at a high temperature, grinding the tellurium copper slags, mixing ground tellurium copper slags with a concentrated sulfuric acid to calcine, enabling the mass ratio between the concentrated sulfuric acid and the tellurium copper slags to be (1.2-1.5):1, maintaining the calcination temperature in a range from 450 DEG C to 600 DEG C and maintaining the calcination time in a range from 3 hours to 5 hours; (2) alkaline leaching to separate the tellurium, leaching obtained calcination slags by a sodium hydroxide alkaline liquor, and then filtering to obtain a tellurium containing alkali leaching liquid and alkali leaching slags; (3) oxidizing the alkali leaching liquid, oxidizing the tellurium containing alkali leaching liquid by sodium hypochlorite of an oxidant and then filtering to obtain sodium tellurate filtered slags; and (4) acid dissolution reduction, dissolving the sodium tellurate filtered slags by a chloridion containing acidic system, adding a reducing agent to achieve reduction and then filtering to obtain tellurium powders. According to the method for extracting the tellurium from the tellurium copper slags, a complete separation of copper, selenium and tellurium can be fully achieved, a comprehensive recovery of the copper, selenium and tellurium can be achieved, the technological process is simple, tellurium dioxide of an intermediate product is not required, the tellurium powders with a high purity can be directly produced, and the tellurium powders can serve as raw materials of 6N high purity tellurium.

Description

technical field [0001] The invention relates to the technical field of nonferrous metal smelting, in particular to a method for extracting tellurium from tellurium copper slag. Background technique [0002] With the development of science and technology, the rare element tellurium has become an important material required for the development of electronic computers, communications, aerospace, energy, medicine and health industries. The content of tellurium in nature is very low, there are few separate mines, and it is mainly associated with chalcopyrite. Copper anode mud fire refining soda slag (commonly known as soda slag) is the main raw material for extracting tellurium in traditional industries. In the copper anode slime refining process, sodium carbonate and telluride are combined to form soda slag, and the main component of soda slag is Na 2 CO 3 , NaO, Na 2 TeO 3 , due to Na 2 TeO 3 It is easily soluble in water, and generally uses water leaching + alkali leach...

AI Technical Summary

Problems solved by technology

But this process is not suitable for the treatment of tellurium-copper slag described in the text, the main reasons: one, this process can not solve the problem of separation of selenium and tellurium-copper, because the roasting temperature of this process (maximum temperature is 250 ℃) is lower than selenium oxide volatilization The lowest temperature is 335°C, and it is impossible to separate selenium and tellurium-copper; 2. The roasting effect of the tellurium-copper slag is poor, and the tellurium in the tellurium-copper slag exists in the form of cuprous telluride. Copper accounts for a relatively high proportion of the total weight of the material, and the oxidation degree of sulfated roasting under low temperature conditions is not enough. According to the inventor's experimental results, the leaching rate of tellurium after sulfated roasting of tellurium-copper slag is lower than 50% when the temperature is lower than 400 ° C.

The patent application No. 201110344761.5 proposes a process of oxidation and reduction treatment of tellurium alkali immersion solution to obtain tellurium dioxide. This process uses hydrogen peroxide as an oxidant. Hydrogen peroxide is easy to decompose under alkaline conditions, resulting in low oxidation efficiency and large consumption of chemicals. In practical applications, the consumption of hydrogen peroxide is generally 6-8 times the theoretical amount; the process of reducing and producing tellurium dioxide is difficult to control in practical applications. A small amount of sodium sulfite will lead to a decrease in the recovery rate of tellurium, and a large amount of sodium sulfite will produce elemental tellurium and affect the dioxide quality of tellurium

The above two patents use soda slag as the processing object, extract tellurium in the form of tellurium dioxide, and then follow the conventional process of alkali dissolution, impurity removal, and electrowinning to extract tellurium. This kind of process is complicated and the cycle is long.

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