Method for extracting silver from gold separating residues

Abstract

The invention discloses a method for extracting silver from gold separating residues. The method comprises the following steps that firstly, reductive dechlorination is carried out on the gold separating residues in an alkaline system by using a reducing agent, so that silver chloride and impurity metals are reduced and converted into elementary substances; secondly, reducing slag is oxidized and dissolved with hydrogen peroxide in a nitric acid-sulfuric acid mixed system, so that silver enters the solution in the form of silver nitrate, and lead enters silver separating residues in the form of lead sulfate; thirdly, hydrochloric acid is added into the silver nitrate solution for precipitation to produce a pure silver chloride intermediate product, and regenerated nitric acid is returned for oxidation and silver separation; and finally, pure silver chloride is reduced into elemental silver powder in an alkaline system by using the reducing agent, and the silver powder is subjected to ingot casting after being washed and dried. The method has the advantages that the essence lies in that efficient recovery of silver in the gold separating residues is realized in a reductive dechlorination and oxidation silver separation mode, the silver direct recovery rate is high, the technological process is stable, the product purity is high, and the problem of environmental pollution existing in a traditional nitric acid dissolution method can be solved.

Description

technical field [0001] The invention relates to a precious metal extraction metallurgical process in the field of nonferrous metallurgy, in particular to a hydrometallurgical method for effectively extracting silver from gold separation slag. Background technique [0002] Gold and silver are rare strategic precious metals, widely used in jewelry, currency reserves and high-tech industries. The main resources for gold and silver extraction are ore, heavy metal smelting by-products and secondary resources. In recent years, with the substantial increase in the production of heavy metals in my country, the by-products of heavy metal smelting have become one of the indispensable resources for the extraction of gold and silver in my country. [0003] No matter what kind of raw materials are used to extract precious metals, the principle of continuous enrichment is usually followed, and the precious metal enrichment is obtained by pyrometallurgy or hydrometallurgy, and finally fur...

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Problems solved by technology

[0006] The advantage of these two processes is that they can directly use reagents to selectively dissolve silver, but there are disadvantages respectively: sodium sulfite leaching-formaldehyde reduction process, first, the concentration of reagents in the leaching process is too high, and the concentration of sodium sulfite reaches 252g/L. Crystallization precipitates and blocks the pipeline; second, the silver concentration in the solution is only about 30g/L, requiring a large liquid-solid ratio, result

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