Extraction technology of rare and precious metals from selenium-removed residues

For extracting rare and precious metals in the selenium-removed residues produced by vacuum distillation of crude selenium, the alkaline oxidation roasting/sulfation roasting−hydrometallurgy combined cascade treatment processes were developed, and the effects of different treatment methods on the leaching efficiencies of rare and precious metals in selenium-removed residues were compared and studied. The results show that, when the alkaline oxidation roasting−hydrometallurgy combined process is used to treat selenium-removed residues, the leaching efficiencies of Au, Ag, Pt and Pd are 53.18%, 18.32%, 96.64% and 98.14%, respectively, the leaching efficiency of Se is more than 99%, and the leaching efficiencies of Te and Cu are 74.66% and 83.55%, respectively. When the sulfated roasting−hydrometallurgy combined process is used to treat Se-removed selenium-removed residues in cascade, the leaching efficiencies of Au, Ag, Pt and Pd are 99.33%, 99.95%, 96.49% and 95.26%, respectively, the leaching efficiency of Se is 99.97%, and the leaching efficiencies of Te and Cu are 98.52% and 99.98%, respectively. The alkaline oxidation roasting−hydrometallurgy combined cascade treatment process has serious corrosion on equipment and containers, and is difficult to operate. The sulfation roasting− hydrometallurgy combined cascade treatment process has better recoveries of Au, Ag, Te, and Cu than the alkaline oxidation roasting process. It is easy to operate and can be directly grafted onto the existing production line. It has broad application prospects. © 2023 Central South University of Technology. All rights reserved.