Resource utilization of hazardous materials: Highly efficient separation and recovery of tin and copper of the tin refining sulfur slag

Tin refining sulfur slag (TRSS) is a typical hazardous materials generated during the crude tin refining process, which has a high economic utilization value due to rich in tin and copper etc. strategic metal. This paper proposes a process strategy for the efficient separation and recovery of tin and copper from TRSS using chalcopyrite and TRSS synergistic smelting-vacuum volatilization to reduce the stockpiling of hazardous materials and to achieve high value utilization of TRSS. The reaction mechanism of chalcopyrite to promote the separation of tin and copper in TRSS was investigated using thermodynamic calculations, TG-DSC, XRD, SEM and vacuum volatilization experiments of Sn and CuFeS2. The results show that CuFeS2 can convert tin into volatile SnS, while the Cu2S and FeS produced by the reaction improve the efficiency of SnS generation. Under the optimized process conditions of 1373 K, 70% chalcopyrite addition, 10 Pa, and 3 h, the recovery rates of Cu and Fe in the residue reached 99.64% and 99.44%, respectively, and the recovered Cu2S and FeS could still be used as sulfurizing agents, and the recovery rate of tin in the volatiles reached 99.87%, and the purity of SnS could reach more than 93 %. The process provides a new method for recovering tin and copper from TRSS with high efficiency, simple operation and excellent environmental benefits.