Production of zinc oxide by ammonia water circulation method

Abstract

The invention relates to a production process of zinc oxide by the ammonia water circulation method, which comprises eight procedures of (1) sulfuric acid leaching; (2) removing iron and manganese byoxidation; (3) removing heavy metals by replacement; (4) synthesizing basic zinc carbonate; (5) filtering and drying; (6) calcining and smashing; (7) treating waste liquid of ammonium sulfate; and (8)absorbing ammonia gas, wherein, the treatment of the waste liquid of the ammonium sulfate (7) comprises the steps of adding calcium hydroxide in the waste liquid of the ammonium sulfate, the ammoniagas produced by reaction is introduced into the ammonia gas absorption procedure (8) for generating ammonia water, introducing carbon dioxide into the ammonia water, then returning to the synthesis procedure (4) and continuing the reaction with solution of zinc sulfate, thereby realizing circulation and reutilization of the ammonia water. The production process can avoid the process of concentration and crystallization or heating and steaming of ammonia, be characterized by simple and easy process and low production cost, simultaneously avoid the production of a large number of byproducts of the ammonium sulfate, have no emission of waste water and reduce environmental pollution.

Description

technical field [0001] The invention belongs to a preparation process of zinc oxide, in particular to a process for producing zinc oxide by an ammonia water circulation method. Background technique [0002] At present, the wet production process of zinc oxide at home and abroad can be roughly divided into several types such as zinc hydroxide method, zinc carbonate method and basic zinc carbonate method. The basic zinc carbonate method can be divided into two types: sodium carbonate method and ammonium bicarbonate method. The former is the main process route for the production of active zinc oxide internationally in the 1970s and 1980s, and the latter is a low-cost process route that has only been industrialized in recent years. The typical process is: using cheap zinc calcine or zinc fume as the main Raw materials are first leached with sulfuric acid, and then filtered, washed and purified to obtain pure zinc sulfate solution. Then neutralize with sodium hydroxide, sodium ...

AI Technical Summary

Problems solved by technology

[0012] Although the above process no longer needs to concentrate and crystallize ammonium sulfate, it still needs to waste a lot of heat energy to distill ammonia by heating

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