Technology for recovering silver from zinc hydrometallurgy leaching residue

Abstract

Disclosed is a technology for recovering silver from a zinc hydrometallurgy leaching residue. The technology comprises the following steps that (1) primary leaching is conducted, wherein silver in the leaching residue is leached through a leaching agent; (2) circulation is conducted, wherein part of primary leaching liquid returns to the primary leaching self-circulation working procedure, and part of the primary leaching liquid enters a replacement working procedure; (3) replacement is conducted, wherein the primary leaching liquid is replaced with metal zinc; (4) secondary leaching is conducted, wherein liquid formed after replacement is used for leaching a primary leaching residue so as to conduct secondary leaching; and (5) secondary leaching liquid returns to the primary leaching residue working procedure. According to the invention, due to the dissolution feature of silver chloride in water, namely, due to the facts that silver chloride is matter insoluble in water, but when the concentration of chloride ions is quite high, coordination ions are formed, and the solubility is sharply improved, silver in the zinc leaching residue with low-grade silver is leached through a calcium chloride solution, the leaching rate of silver is 88.7% to the maximum extent, the leaching rate of silver chloride and silver sulfate can be 99%, the technology is simple in process and easy to operate, the leaching agent is low in price, and the technology cost is low. The recovery rate of silver is high, and the extensive popularization is facilitated.

Description

technical field [0001] The invention belongs to the technical field of non-ferrous metal smelting, and in particular relates to a process for recovering silver from zinc leaching slag in a hydrometallurgy process. Background technique [0002] Domestic zinc smelting enterprises will produce millions of tons of zinc leaching slag every year, and the silver content in the leaching slag is generally 200-300g / t. It has important economic and social significance. [0003] At present, there are two main types of silver recovery from zinc leaching slag: fire method and wet method: fire method recovery, high energy consumption, will generate soot, flue gas and slag during the recovery process, which is not environmentally friendly; wet method recovery mainly includes flotation cyanide method, thiourea method, sodium thiosulfate method, etc.; the flotation method has a simple process flow and low production cost, but the recovery rate is closely related to the properties of the leac...

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Problems solved by technology

[0003] At present, there are two main types of silver recovery from zinc leaching slag: fire method and wet method: fire method recovery, high energy consumption, smoke, smoke and slag will be generated during the recovery process, which is not environmentally friendly; wet method recovery mainly includes flotation method, cyanide method, thiourea method, sodium thiosulfate method, etc.; the flotation method has a simple process and low production costs, but the recovery rate is closely related to the properties of the leaching residue, mainly for silver sulfide, while the hydrometallurgy zinc leaching The main component in the slag is silver chloride, the recovery rate of the flotation method is low, and the effect is not ideal; the cyanidation method uses highly toxic cyanide, which causes serious pollution, and the recovery rate of silver is low. Generally, silver concentrates cannot be processed. Large-scale promotion; although the thiourea method is non-toxic and has a fast leaching speed, thiourea is expensive, and the cost for reclaiming low-grade silver slag is too high, so it is not suitable for large-scale application; the sodium thiosulfate method is very unstable because the reagent Too much consumption is also difficult for industrialized production;

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