Reduction Mechanisms During the Recovery of Mo and Fe via Molten-Bath Smelting of Copper Slag and Waste MoSi2

Molybdenum (Mo) finds extensive applications in the steel industry, and the recycling of secondary molybdenum resources is crucial for the green development of the molybdenum sector. Meanwhile, the large-scale stockpiling of copper slag, a bulk industrial solid waste, poses severe environmental and resource-related challenges. Addressing the common issues of the refractory nature of waste molybdenum disilicide (MoSi2) and the underutilization of iron resources in copper slag, this study proposes a synergistic smelting approach using copper slag and waste MoSi2, aiming to realize the coordinated treatment of these two solid wastes and the simultaneous, efficient recovery of valuable metals (Mo and Fe). Under non-isothermal conditions, this work elucidates the phase evolution of copper slag and the decomposition–reduction behavior of MoSi2; clarifies the dual role of coke as the primary reductant at the initial reaction stage and as a maintainer of a reducing atmosphere during smelting; and systematically investigates the effects of smelting temperature, slag basicity, and coke dosage on metal recovery. The results demonstrate that, under optimized process conditions, the recovery efficiencies of molybdenum and iron can reach 98.97% and 98.46%, respectively. This study provides a new strategy for the enrichment and extraction of metallic elements from waste MoSi2 and copper slag.