Influencing factors and kinetics analysis of a new clean leaching process for producing chromate from Cr–Fe alloy

Abstract

Abstract In the traditional leaching process for producing chromate from chromite ore, large quantities of chromium-containing residues and dusts are discharged, creating serious environmental pollution. In order to solve this serious environmental problem and realize a clean production process for chromate, a new cleaning process using a Cr–Fe alloy as a raw material has been developed, in which the pollution problem of chromium-containing residues caused by the leaching process is resolved. The effects of leaching temperature, reaction time, particle size, stirring rate, and liquid-to-solid ratio in the leaching process have been investigated in this study. The experiment results show that the leaching ratio of the Cr and Fe in the alloy can be greater than 97% at a leaching temperature of 90 °C, a liquid-to-solid ratio of 3:1, an alloy powder particle size of 200 mesh, a stirring rate of 300 rpm and a leaching time of 6 h. Kinetic analysis was carried out, and the calculated activation energy for chromium leaching was 43.94 kJ/mol, indicating control of this process by a chemical reaction on the particle surface. In the proposed process for producing chromate from a Cr–Fe alloy, chromium is present in the form of Cr3+, so the pollution problem of hexavalent chromium residues can be resolved and clean production can be realized.