Recovery of Copper and Cobalt from Converter Slags via Reduction–Sulfurization Smelting Using Spent Pot Lining as the Reductant

Abstract

Large amounts of solid wastes are produced in copper and aluminum smelting processes, which not only cause losses of valuable resources but also threaten the ecology and environment. In this study, a reduction–sulfurization smelting method was used for recovering Cu and Co from converter slags by using spent pot lining (SPL) as the reductant. CaO was added to fix the fluorine from SPL into the cleaned slag. Thermodynamic analysis and experiments were performed to verify the feasibility and determine the optimal conditions of this smelting process. The optimum reductant addition of spent cathode carbon block (SCCB) and spent SiC side block (SSCB) was 8–12 wt %, and the copper and cobalt recovery reached more than 98 and 96%, respectively. The addition of 10 wt % CaO for SCCB improved slag viscosity and promoted the separation between slag and matte/alloy and fixed fluorine in the cleaned slag in the form of insoluble calcium fluoride. The metallized Cu–Co matte was obtained, in which Cu mainly existed in the form of sulfide and Co mainly existed in the form of an iron cobalt alloy.