Wet detoxification method for chromium slag and chromium-containing pollutants

Abstract

The invention relates to a wet detoxification method for chromium slag and chromium-containing pollutants. The wet detoxification method comprises the following steps: screening and crushing the chromium slag and the chromium-containing pollutants, performing wet milling on the chromium slag and the chromium-containing pollutants in a ball mill, adding a filtrate containing sulfate ions, leaching out acid-soluble calcium chromate in chromium slag slurry, adding the chromium slag slurry and a first reducing agent sequentially into a reaction tank, stirring and mixing the chromium slag slurry with the first reducing agent to perform reduction reaction, reducing the acid-soluble calcium chromate in chromium slag slurry to trivalent chromium, adding concentrated sulfuric acid and to stirring and mixing for regulating, adjusting pH value of the chromium slag slurry to be 7+/-0.5, then adding a second reducing agent into the reaction tank and stirring and mixing for reducing, stirring the reduced slag slurry to cure the reduced slag slurry, and converting hexavalent chromium in the chromium slag slurry to chromic hydroxide sediment; and separating solid and liquid of the cured chromium slag slurry. The wet detoxification method has the characteristics of low cost, no waste liquid, no slag returning phenomenon, good detoxification effect and capability of being applicable to the large-scale industrial production.

Description

technical field [0001] The invention relates to a wet detoxification method for chromium slag and chromium-containing pollutants, and belongs to the technical field of chromium pollution restoration treatment. Background technique [0002] Chromium slag and chromium-containing pollutants mainly refer to the residues produced in the production process of metal chromium and chromium salt production enterprises, especially the production enterprises with calcium roasting production process, and the soil, rocks, construction waste, etc. polluted by such residues , belongs to heavy metal hazardous waste, among which, the toxicity of hexavalent chromium is much greater than that of trivalent chromium. Hexavalent chromium has strong carcinogenic and mutagenic properties, and is one of the 129 key pollutants confirmed by EPA. Hazardous treatment will seriously affect the health of the surrounding people. [0003] At present, there are mainly two harmless treatment processes for chr...

AI Technical Summary

Problems solved by technology

However, due to the presence of a certain amount of ferrous ions in the circulating water used by wet ball milling, this detoxification method will react with sodium sulfide to produce ferrous sulfide precipitation, resulting in extra loss of sodium sulfide, which not only increases the cost of detoxification, but also reduces the effective rate. Reduction effect of ferrous ions on chromium

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