Integrated process for recycling copper anode slime from electronic waste smelting

Electronic waste (e-waste) is one of the fastest growing and most valuable waste. In industry, the final disposal of e-waste is usually through copper smelting and followed by electro-refining. Compared to the conventional copper anode slime, the anode slime from e-waste smelting is much more valuable and complicated. The major components are gold, silver, tin, lead and antimony. In this paper, an integrated process has been put forward to recycle these metals. To decrease the dissolution of impurities and enhance gold recovery rate, NaClO3-NaCl-H2SO4 solution was chosen as leaching agent for gold recovery. The concentration of Cl− and H+ can be controlled by the leaching system. After selective extraction of gold and silver, the residue mainly consists of PbSO4, SnO2 and Sb2O5. Then PbSO4 was dissolved and removed in HCl-NaCl-CaCl2 solution at 95 °C. SnO2 and Sb2O5 were transformed into soluble materials via alkali smelting with NaOH. The Na2SnO3 was recovered by washing, evaporation and crystallization. The insoluble matter, mainly containing NaSbO3, was leached by the HCl-NaCl solution, followed by hydrolysis and aging. The results showed that, under the optimum conditions, the direct recovery ratio of Au, Pb, Sn, and Sb was 98.1%, 99.1%, 92.3% and 97.1%, respectively. Moreover, the wastewater was reused as much as possible. This integrated process is highly efficient and environmental conservation.