Re-calcination and extraction process for the detoxification and comprehensive utilization of chromic residues

Abstract

A re-calcination and extraction process for the detoxification and comprehensive utilization of chromic residues, comprising adding small amount of residue ore powder, sodium carbonate, or additionally, a certain amount of coke powder to the poisonous chromic residues, and calcining the mixture in a re-calcinating apparatus at 1000.degree.-1200.degree. C., for 30-60 minutes. The re-calcined grog is extracted with water, to obtain an extractive liquor containing sodium chromate. The extractive liquor can be used to produce chromium oxide, basic chromium sulfate or medium chrome yellow; while the extracted residues can be sintered at high temperatures with iron ore powder and coke to obtain a massive self-melting sintered iron, which can be further converted to a low-chromium cast iron. This process can thoroughly detoxify the chromic residues, effectively recover Cr2O3 and remove water-soluble Cr+6, whereby various important industrial materials are produced. The method brings very good economical and environmental benefits.

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