Method for recovering bismuth from bismuth slag

Abstract

The invention relates to a method for recovering bismuth from bismuth slag, which includes steps of: firstly, smelting silver-refining converter oxidizing slag in high-temperature restoring mode to obtain lead-bismuth alloy, performing silico-fluoric acid system lead-bismuth alloy electrolysis to obtain electric lead products and high-bismuth anode mud; secondly performing hydrochloric acid leaching on the high-bismuth anode mud, filtering to obtain bismuth-contained leaching liquid, wherein the leaching condition is that: liquid-solid ratio (weight ratio) is 3-6:1, process temperature is 40-70 DEG C, hydrochloric acid concentration is 150-200g / L, and reaction time is1.5-2.5h; and thirdly, replacing bismuth in the leaching liquid through reduced iron powder to obtain sponge bismuth and obtain refined bismuth with high purity in pyro-refining electrolysis. Sodium sulfide for sedimenting silver is added in the leaching process to obtain bismuth leaching liquid, silver can be prevented from immersing into the liquid as much as possible, when return washing liquid is used for leaching high-bismuth anode mud, a part of hydrochloric acid is refilled to maintain necessary potential of hydrogen (pH) value, concentration of Cl- is controlled to be 150-200g / L, and simultaneously bismuth ion hydrolysis can be avoided. Compared with the prior art, the method has no operations of water quenching, ball milling, hydrolysis, neutralization and the like of coarse bismuth alloy, has less procedures, is low in cost and free of pollution, simultaneously achieves double-metal electrolysis of the lead-bismuth alloy and does not influence the electric-lead main system.

Description

technical field

[0001] The invention relates to a method for recovering bismuth from bismuth-containing slag, and belongs to the technical field of nonferrous metal smelting combined with fire method and wet method. Background technique

[0002] For the lead anode slime produced by lead electrolysis, bismuth metal is oxidized into the slag during the traditional silver-fired recycling process of separating the silver converter into the slag. The traditional process of recovering bismuth metal from the slag generally adopts the combined process of fire method and wet method, or The process of pure fire refining to remove impurities and produce bismuth metal. The thermal treatment process is more direct and simple, with less process and land occupation, and no sewage treatment problem; while the wet process is difficult to solve due to environmental problems such as sewage treatment, as well as constraints such as equipment corrosion, many processes, and difficult liquid-solid...

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