Method for extracting electrolytic zinc from oxide material containing less than 20% of zinc by using waste acid in titanium white plant

Abstract

The invention discloses a method for producing electrolytic zinc, which comprises the following steps: (1) producing the electrolytic zinc from oxide material containing less than 20% of zinc serving as a raw material and by taking waste acid in a titanium white plant as a leaching agent, namely by using two wastes; (2) grinding the oxide material to obtain 80 to 100-mesh material and leaching zinc in the material by using the waste acid for about 3 to 4 h so as to obtain soluble zinc sulfate; (3) filtering and adding lime milk to regulate the pH value to 5.4 and hydrolyze impurities and rare metals in the solution to be separated out in the form of precipitate; (4) adding zinc powder into the solution without the impurities so that copper and cadmium in the solution perform replacement reaction to generate cooper and cadmium-containing precipitates which are commonly called 'copper and cadmium slag'; (5) separating the zinc from ferrous iron in the solution without cobalt, namely, hydrolyzing zinc sulfate in the solution by using lime milk as a precipitant to generate white zinc hydroxide precipitate; (6) filtering the zinc hydroxide precipitate, heating the obtained solution to about 70 DEG C and introducing air to oxidize the ferrous iron to ferric iron; and adding a proper amount of oxidant so as to oxidize the ferrous iron in the solution to the ferric iron and separate out the ferric iron in the form of precipitate, namely, removing iron by a 'goethite process'; (7) dissolving the precipitate by the electrolyzed solution and filtering, wherein the filter residue is used for preparing 'gypsum', the solution is subjected to impurity removal, evaporation, concentration and crystallization, the crystallization mother solution is returned to the leaching process, and the crystal is dissolved by water and used for preparing electrolyte; and (8) electrolyzing, stripping, melting and casting into a zinc ingot.

Description

Technical field: [0001] The invention relates to a method for producing electrolytic zinc from oxidized materials with a zinc content below 20% by using waste acid from a titanium dioxide factory. technical background: [0002] Because the waste acid in the titanium dioxide factory cannot be effectively utilized, the current treatment method is mainly to adopt the method of concentration, that is, to concentrate the waste acid with a sulfuric acid content of about 20% into concentrated sulfuric acid with a content of 80%, and then return it as titanium concentrate acid for leaching. Due to the low content, the calorific value during leaching cannot reach the required temperature for dissolving titanium concentrate, and the harmful elements calcium and magnesium contained in titanium dioxide product quality are relatively high, thus affecting product quality. The cost of concentration is relatively high, and it takes four tons of waste acid to concentrate one ton of concentr...

AI Technical Summary

Problems solved by technology

[0003] As an oxidized material with a zinc content below 20%, due to the limitation of production cost, it is impossible to use industrial grade sulfuric acid to produce electrolytic zinc, so it is basically discarded

Images