Method for evaporation-free preparation of zinc sulfate from brass slag material

Abstract

A method for evaporation-free preparation of zinc sulfate from a brass slag material is characterized by comprising the steps: taking a light ash material of the brass slag material, adding water according to the solid-liquid mass ratio of 1:14-16, carrying out pulp conditioning, and carrying out neutral leaching with concentrated sulfuric acid; then extracting by a P204 extraction agent, and washing with a dilute sulfuric acid solution with the pH value of 2.0-2.5; next carrying out first-class cross-flow back extraction by a sulfuric acid solution with the concentration of 350-450 g/L, carrying out repeated back extraction, and then separating out zinc sulfate; carrying out second-class cross-flow back extraction of a zinc-containing P204 oily liquid left in the first-class back extraction with a sulfuric acid solution, and when the zinc concentration reaches about 95+/-10 g/L, supplementing the second-class back extraction solution to the first-class back extraction solution; allowing the P204 oily liquid obtained after second-class back extraction to anew return to the step 2), and carrying out extraction; and finally carrying out cycle operation of feeding, leaching, extracting, washing, first-class cross-flow back extraction and second-class cross-flow back extraction, and separating out zinc sulfate heptahydrate crystals. The method has the advantages of simple process, low energy consumption and high production efficiency; and the prepared zinc sulfate is granular in shape, is bright white in color, and has the quality better than zinc sulfate produced by a concentration distillation method.

Description

technical field [0001] The invention belongs to the technical field of metallurgy and chemical industry, and specifically relates to a method for preparing zinc sulfate by freeing evaporation and crystallization of brass slag. Background technique [0002] Brass slag mainly refers to the slag produced during the smelting of brass, which is re-selected to remove the residue of metallic elements. Brass slag is mostly used to recover zinc. The recovery methods are divided into two categories: wet method and fire method, and wet method has two kinds of direct recovery of metal zinc and recovery of zinc sulfate. [0003] In the crystallization process in the wet leaching process, the solvent is usually evaporated to make the solution from unsaturated to saturated, and if the evaporation continues, the excess solute will be precipitated in the form of crystals; the concentration of zinc sulfate in the solution is low, and it will not occur at room temperature Crystallization occu...

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Problems solved by technology

Since the brass slag also contains a large amount of other metals, such as lead, iron, tin, nickel, etc., some of them will enter the solution during the leaching process, and the impurity removal determines the quality of the zinc sulfate product. There are obvious deficiencies

And Chinese Patent No. 20111010179313.4 discloses a kind of technology that evaporative crystallization method prepares zinc sulfate, although avoided the complex and loaded down with trivial details problem of process step, its evaporative concentration process energy consumption is bigger and speed is slow, and production cost is on the high side, and production efficiency is low; In the process of evaporation and concentration, some impurities are also mixed in the concentrated mother liquor, which will reach supersaturation and precipitate out, which will affect the quality of zinc sulfate products.

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