Recovery of valuable metals from copper smelting open-circuit dust and its arsenic safe disposal

Abstract

In this research, an integrated hydrometallurgical process for comprehensive recovery of valued metals and safe disposal of arsenic from copper smelting open-circuit (CSO) dust was developed. By sulfuric acid leaching, Cu, As, Zn and Cd can be selectively extracted into leachate while Pb and Bi were remained in the residue. Then, iron powder cementation, iron salt precipitation and Na2CO3 neutralization precipitation were adopt to successively recover Cu as sponge copper, remove As mainly as thermodynamically stable ferric arsenate and recover Zn and Cd as basic sulfate. Afterwards, the obtained ferric arsenate residue was solidified by cement with additive fulvic acid (FA). FA had an excellent performance and it can reduce arsenic leachability to 1.5 mg/L. The zeta potential, FTIR and SEM analyses indicated that FA chemically adsorbed onto the surfaces of ferric arsenate residue and cement hydrates through carboxylate groups. FA promoted the deposition of cement or cement hydrates on the surface of ferric arsenate residue, thereby enhancing the physical encapsulation of arsenic residue. This research demonstrates the possibility of comprehensively recovering metals and safely disposing arsenic from hazardous waste CSO dust by the developed integrated hydrometallurgical process, and thus it has good industrial application prospect.