Selective separation of copper and zinc from high acid leaching solution of copper dust using a sulfide precipitation-pickling approach

Abstract

Herein, a new approach for direct separation of Cu and Zn from high acid leaching solution was proposed. The approach includes two steps, Cu and part of Zn first precipitated with H2S, then the Zn in the residue was re-leached using the original leaching solution. Thermodynamics calculation indicates that CuS and As2S3 will generate even the acid concentration is over 8 mol/L, while ZnS is easier to dissolve in acid solution. Therefore, it is possible to selective separate Cu and Zn using H2S under high acid concentration. Key parameters which will affecting the precipitation of Cu and the pickling of Zn are systematically investigated. Under the optimal conditions, the precipitation efficiency of Cu can reach over 99%, and the loss of Zn was only 3.15%. Moreover, more than 96% of As in the leaching solution will also be precipitated. The concentrations of Cu, As, and Zn in the leachate are 0.0722, 0.0893, 48.73 g/L, respectively. The content of Cu in the residue can reach over 57% which could be used for extraction of Cu. XRD results showed that Cu and As were existed as CuS and As2S3 in the residue.