Comprehensive recovery of Sn-Cu bearing residue and preparation of high purity SnO2 and CuSO4·5H2O

Abstract

In the production of tin, much Sn-Cu bearing residue is yielded, and it is an important secondary resource for Sn and Cu recovery but has the disadvantages of a low metal recovery rate and low-concentration SO2 pollution. In this study, alkaline pressure oxidative leaching (APOL) was proposed to dispose of the Sn-Cu bearing residue. Tin was first dissolved as sodium stannate into the filtrate and used for SnO2 synthesis via a hydrothermal process, while copper sulfides were oxidized to copper oxide, and used for CuSO4·5H2O preparation via acid leaching-evaporative crystallization. Under the optimized leaching conditions of APOL, the leaching efficiencies of Sn, As, and S approached 93.42%, 98.82%, and 97.99%, while the leaching efficiency of copper was only 1.60%, which results in the efficient extraction of tin, desulfurization, dearsenification, and separation of tin and copper. The product SnO2 had a purity higher than 99.86%, a morphology of irregular shape, and a mean size of 2.68 μm. Meanwhile, the purity of prepared CuSO4·5H2O reached 99.98% with a morphology of irregular rods. Both valuable metals are economically and efficiently recycled by this environmentally friendly method.