High-Efficiency Oxidant-Free Leaching of Rhenium from Arsenic–Rhenium Filter Cake

Arsenic–rhenium filter cake, one of the main wastes produced by copper smelting systems, is a vital source of rhenium (Re). Using traditional hydrometallurgy methods, rhenium can be leached by sulfuric acid solution with the help of oxidants. However, the residual oxidants can seriously affect the efficiency and lifetime of the extractants and ion-exchange resins. We herein propose a novel method to leach rhenium through a displacement reaction using copper sulfate solution, thereby avoiding the use of oxidants. The results show that Re element exists in the arsenic–rhenium filter cake in two forms: Re2S7 and (As,Re)S amorphous. The rhenium leaching efficiency can reach 93.18%, and the kinetic data fit the shrinking core model. The leaching rate is controlled first by chemical reaction, with an apparent activation energy of 78.46 kJ mol−1. Afterwards, the leaching kinetics of rhenium fits an internal diffusion model. The results provide theoretical guidance on how to make full use of waste residues from copper smelting systems.