Method for preparing pure gold from silver anode mud through potential control

Abstract

Provided is a method for preparing pure gold from silver anode mud through potential control. The silver anode mud is leached out in a nitric acid solution, after nitric acid leaching residue is immersed and digested in concentrated sulfuric acid, coarse gold powder is obtained, hydrogen peroxide is added into a hydrochloric acid solution containing the coarse gold powder to conduct potential controlling and gold leaching by chlorination, slurry is subjected to solid-liquid separation after being cooled, gold leaching liquid is added into sodium hydroxide and sodium sulfite to conduct potential controlling and reduction, and reduction gold powder is obtained, and after the reduction gold powder is subjected to concentrated sulfuric acid refining, pure gold powder is obtained. According to the method for preparing the pure gold from the silver anode mud through potential control, a potential control mode is adopted to achieve adjustment and controllability of the process for preparing the pure gold from the silver anode mud, the gold powder with the purity being 99.99% is prepared, the direct recovery rate of gold reaches to over 99.9%, the method has the advantages of being high in gold direct recovery rate, stable in technological process and high in product purity, and the environmental pollution problem existing in a traditional aqua regia dissolution method is 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 adopting a controlled potential method to prepare Sijiu gold from silver anode slime. Background technique [0002] Gold is a rare strategic precious metal widely used in gold jewelry, currency reserves and high-tech industries. The main resources of gold extraction are gold mines, 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 gold extraction in my country. [0003] Usually, copper concentrate or lead concentrate is produced through pyromelting-electrolytic refining process to produce the main metal, while the precious metal in the raw material is enriched in the anode slime produce...

AI Technical Summary

Problems solved by technology

The second is secondary electrolysis, that is, the silver anode slime is cast into an anode plate by fire method and then subjected to secondary electrolysis in nitric acid solution. However, there is a serious backlog of gold, which limits the application of the secondary electrolysis method

However, the recovery rate of gold and the quality of gold powder are greatly affected by raw materials, especially the problem of exceeding the standard of impurity metals Cu, Ag and Pb is more prominent

Among them, the dissolution of aqua regia is the most classic dissolution process, but it has the disadvantages of long time, incomplete removal of nitrate, generation of harmful gases such as NO, and poor working conditions, and the purity of the reduced gold powder is greatly affected by the raw materials; in addition, this method also requires coarse The silver content in the gold powder should be less than 8% to prevent the formation of AgCl inclusions and cover the surface of the gold powder to hinder the progress of the gold dissolution reaction

[0008] The extraction method is that the coarse gold powder is dissolved in aqua regia and extracted with an extractant, and the loaded organic phase is directly reduced and back-extracted to produce high-quality gold powder. The extractants used include DBC (dibutyl carbitol), MIBK (methyl isobutyl base ketone), DIBK (diisobutyl ketone) and ether, the stripping agent used is an acidic solution containing oxalic acid or sodium sulfite, the extraction method has relatively low requirements on raw materials, strong adaptability, fast production speed, short production cycle, The process has no backlog of gold, high direct recovery rate, and simple operation, but the disadvantages are large investment, high cost and long process, and the product quality is greatly affected by the quality of raw materials

[0009] It can be seen that the gold refining process uses the dissolution-purification-reduction process to achieve gold purification, but there are two common problems. One is that the reagent consumption in the dissolution process cannot be accurately measured, resulting in a large amount of reagent consumption and blind operation. The other is the reduction process. The process cannot effectively control the amount of reagent added, resulting in large consumption of reagents and poor product quality

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