Enhanced Cadmium Extraction from Zinc Neutral Leaching Residue Using Sulfur Dioxide

Enhanced reductive leaching of cadmium from zinc neutral leaching residue, along with zinc and iron, was conducted using sulfur dioxide as reductant. Cadmium mainly exists as cadmium-bearing zinc ferrite (CdxZn(1-x)Fe2O4) (x = 0 similar to 1). The influence of variables on the extraction rates of cadmium, zinc, and iron was studied. The results showed the maximum extraction of cadmium, zinc, and iron reached 99.11%, 93.43%, and 93.38% under the optimum conditions. The raw and the reductive leaching residue were characterized by XRD, ICP, and SEM-EDX analysis. Lead sulfate, zinc, and cadmium sulfide are the main phases contained in the reductive leaching residue.