An efficient and affordable hydrometallurgical process for co-treatment of copper smelting dust and arsenic sulfide residue

We developed a novel method for comprehensive treatment of copper smelting dust (CSD) and arsenic sulfide residue (ASR) using three processes: leaching CSD by sulfuric acid, Cu precipitation with ASR, and FeSO4 & sdot;7H2O/ O2 co-oxidizing and precipitating As. The novel method not only realizes the recovery of valuable metals from dust, but also removes and solidifies As in CSD and ASR in the form of scorodite to achieve harmless treatment. With sulfuric acid as leaching agent, the leaching efficiencies of Cu, Zn and As reached 87.23%, 93.07% and 95.21%, respectively, under the optimum conditions. Subsequently, Cu in CSD leaching solution was precipitated in the form of CuS by ASR, and the Cu precipitation percentage reached 97.39% and 94.86 wt. % of As in ASR entered the solution under the optimum conditions. Finally, FeSO4 & sdot;7H2O/O2 was used to co-oxidize As(III) and simultaneously precipitate the As in the form of scorodite. The oxidation percentage and precipitation percentage of arsenic reached 98.73% and 96.77%, respectively. The leaching concentration of As in the arsenic precipitate residue (APR) was only 0.17 mg/L in the toxicity characteristic leaching procedure (TCLP). The arsenic precipitate solution can be directly used to recover Zn.