A method for recovering tellurium from tellurium anode slime

Abstract

The invention relates to a method for recycling tellurium from tellurium anode slime. By adopting the technical scheme, the method comprises the steps that firstly, distilled water is used for washing tellurium anode slime, hydrogen peroxide is used for completely oxidizing uncleaned Na2TeO3 into Na2TeO4, then, sulfuric acid is slowly added into the tellurium anode slime to leach out tellurium, filtering is performed to obtain a tellurium leaching agent, Na2SO3 is used for reducing Te6+ into crude tellurium powder, then, a saltpeter solution is adopted for dissolving the crude tellurium powder, tellurium electrodeposition regularly-discharged liquid waste or tellurium anode mud washing water is added into the solution for neutralization, the pH value of the reaction endpoint is controlled to 5-6, tellurium is totally converted into tellurium dioxide, impurities are removed from the neutralized solution, finally, the tellurium dioxide is dissolved through the tellurium electrodeposition liquid waste, the solution composition is adjusted to meet the requirement of electrodeposition new liquid compositions, and the solution is returned to the electrodeposition process to produce refined tellurium. Tellurium in anode mud produced by tellurium electrodeposition can be supplemented in time for performing process production tellurium refining, the resource utilization efficiency is improved, the technology is reasonable, operation and implementation are easy, and the tellurium recovery rate is high.

Description

technical field [0001] The invention relates to a method for recycling tellurium from tellurium anode slime. Specifically, it is a method for recycling hexavalent tellurium in anode slime produced by tellurium electrowinning back to the process to produce refined tellurium, which belongs to chemical technology field. Background technique [0002] At present, the production of refined tellurium adopts the electrowinning process. First, the qualified tellurium dioxide is dissolved with sodium hydroxide and configured into Na 2 TeO 3 For electrolysis, stainless steel plates are used as cathode and anode plates, and then electrolysis is performed. The metal tellurium flakes are precipitated at the cathode, and the tellurium flakes are washed with water, dried, and cast into ingots to obtain refined tellurium; the anode reacts to precipitate oxygen. However, part of tetravalent tellurium in the electrolytic solution will also undergo side reactions at the anode and be oxidized...

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Problems solved by technology

[0003] The conventional treatment method for tellurium anode slime is as follows: leaching with sulfuric acid first, then adding hydrochloric acid or sodium chloride, using sodium sulfite to convert hexavalent tellurium into tetravalent tellurium in a high-acid and high-chlorine system, and then neutralizing it into tellurium dioxide. The disadvantage of the method is that the conversion rate of tetravalent tellurium is low, and some tellurium is converted into elemental tellurium due to over-reaction, and high acid and high chlorination are used, the working conditions are harsh, the equipment is corroded, and the cost is high

Patent CN 105399062 A mentions sulfuric acid leaching—reduction of tetravalent tellurium by iron powder—alkaline neutralization of tellurium anode slime treatment method to recycle tellurium into tellurium dioxide. Although this method can improve the conversion rate of tellurium dioxide, it introduces Impurity iron is removed, and after recovery, it needs to be purified again to meet the product purity requirements.

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