A potential industrial waste–waste co-treatment process of utilizing waste SO2 gas and residue heat to recover Co, Ni, and Cu from copper smelting slag

A potential industrial waste-waste co-treatment process was proposed and verified for the recovery of valuable metals Co, Ni, Cu from copper smelting slag by utilizing high temperature SO2 off-gas. Sulfation roasting followed water leaching under designed thermodynamic conditions conducted to facilitate selective formation sulfates while separating iron as oxide. Several parameters were studied such temperature, time, addition Na2SO4, agent. Under optimized sulfation (Gas flow: 500 mL/min, 5% + 20% O2 75% Ar; Roasting temperature: 650 °C; time: 4 h; Addition Na2SO4: 30%) (Leaching 80 Leaching 5 solid liquid ratio: 0.05 g/mL), extraction yields shown reach 95.8% 91.8%, 81.6%, respectively. Furthermore, – confirmed on lab-scale a feasible efficient way recover mechanism determined microstructural evolution. Finally, environmentally friendly in terms energy flow material presented based preliminary assessments environmental benefits, economic heat recovery.