A novel slag cleaning method to recover copper from molten copper converter slag

Abstract

To recover copper from copper slag, a novel slag cleaning method was proposed. The thermodynamics and binary phase diagram of FeO–SiO2 were calculated first. Then, the effects of experimental parameters on the reduction of Fe3O4, recovery of copper, and slag cleaning mechanism were investigated. The results showed that the addition of SiO2 significantly reduced the initial reduction temperature of magnetite and pyrite. The contents of Fe3O4 and copper decreased to 2.45 wt.% and 0.39 wt.%, respectively, with copper recovery of 92.52% under the optimum conditions. More than 94% silver and 99% gold subsided into the copper matte after slag cleaning. Approximately 72% of zinc and 75% of lead volatilized in the flue gas. The viscosity of the copper slag decreased from 0.68 to 0.12 Pa·s due to the reduction of magnetite. The sedimentation of copper matte droplets could be enhanced by mechanical stirring.