Non-ferrous metal smelting high-arsenic contaminated acid arsenic fixing process

Abstract

The invention relates to a non-ferrous metal smelting high-arsenic contaminated acid arsenic fixing process which sequentially includes the steps: pre-neutralization, to be specific, mixing iron-containing slag or iron-containing reagents and smelting contaminated acid, controlling Fe/As molar mole ratio, throwing mixed slurry and the contaminated acid into a pre-neutralization tank, performing reaction, controlling the pH (potential of hydrogen) value of solution, thickening pre-neutralization slag slurry to obtain bottom flow, supernate and gypsum slag, and using the gypsum slag as a cementretarder for sales; oxidation, to be specific, supplementing iron sulfate serving as an iron source reagent as required, heating the pre-neutralized supernate, adding hydrogen peroxide serving as an oxidizing agent for oxidation, controlling oxidation-reduction potential, and completely oxidizing trivalent arsenic into pentavalent arsenic; crystal form iron arsenate precipitation arsenic fixing, to be specific, controlling reaction temperature, adding seed crystals, controlling reaction endpoint pH values by adding lime milk, and conveying bottom flow subjected to two-stage arsenic precipitating reaction to a landfill through filter-pressed crystal form iron arsenate solids. The arsenic fixing process has the advantages of simple process, low cost, good treatment effects, low environmentalpollution risk and the like and is applicable to non-ferrous metal metallurgy industries.

Description

technical field [0001] The invention relates to an arsenic-fixing process for nonferrous metal smelting high-arsenic polluted acid, which is suitable for application in the nonferrous metal metallurgy industry. Background technique [0002] Non-ferrous metals are important resources needed for industrial development. my country is rich in mineral deposits. Due to the high content of arsenic in non-ferrous metal ores, it is inevitable to produce A large amount of acidic wastewater, the acidic wastewater industry is called dirty acid. The polluted acid system is complex, with many components and high concentration. It mainly contains high concentrations of arsenic, sulfate ions, fluoride ions, and chloride ions, as well as copper, zinc, lead, cadmium and other metals. With the continuous development of non-ferrous smelting technology, many problems about the treatment of dirty acid and the reduction, stabilization and harmless treatment of arsenic-containing waste residues nee...

AI Technical Summary

Problems solved by technology

At present, there have been many reports on the synthesis method of scorodite: First, Outotec’s authorized patent CN102307813B discloses “a method for removing arsenic as scorodite”, which uses an oxidant to oxidize iron to trivalent and arsenic to pentavalent. valence, and precipitate iron and arsenic into amorphous ferric arsenate under normal pressure, then send the formed ferric arsenate precipitate to 150-200°C for hydrothermal conversion, and process it into crystalline scorodite. The shortcoming of this method is to first enrich ferric arsenate, and then transform it into crystalline scorodite through high temperature and high pressure. Arsenic treatment method", firstly add calcium oxide to arsenic-containing polluted acid, separate solid-liquid to obtain gypsum, then add iron salt and oxidant to the supernatant after solid-liquid separation, at a lower Fe/As molar ratio of 0.8- Under the conditions of 1.2:1 and a certain pH value of 1.8~4, the arsenic in the dirty acid is first formed into amorphous iron arsenate precipitation, and then the acid is added to dissolve and heated (80~95°C), and the solid and liquid are separated to obtain gypsum and odor. Mixed precipitation of allionite, the supernatant after solid-liquid separation is added with ferric salt and calcium oxide for deep arsenic removal to meet the discharge standard. This method has ferric arsenate and acid back-dissolution. The pH value control and the addition of crystal seeds are not disclosed. problem, and there should be problems of low conversion efficiency and incomplete conversion at a temperature of 80-95°C, plus the two arsenic precipitation processes require two solid-liquid separations, and the supernatant after solid-liquid separation is still Deep arsenic removal treatment is required, the whole process is complicated, and the problem of scorodite conver...

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