Combined flotation-oxygen pressure leaching process for treatment of copper smelting slag with a high oxidation rate and its kinetic study

Abstract

A process route combining flotation for recovering easily floatable sulfide copper minerals and oxygen pressure acid leaching (OPAL) was employed to comprehensively recover valuable metals (Cu, Mo, Fe, etc.) from copper smelting slag with a high oxidation degree. The oxidative leaching process selectively dissolved and recovered Cu and Mo while transforming Fe into leach residue, rendering it suitable as a raw material for iron and steel smelting. Under optimal conditions, the leaching recoveries for Cu and Mo reached 96.87% and 95.39%, respectively, with over 90% of Fe in the residue phase. Kinetic studies revealed that the OPAL process conforms to the shrinking core model without a solid product layer. The leaching rate was initially controlled by the chemical reaction, transitioned to mixed control during the intermediate stage, and was finally governed by diffusion through the solid product layer in the later stage. Based on this, the kinetic equations for Cu and Mo leaching during the chemically controlled stage were fitted and calculated, and the reaction model was established.