An environmentally-friendly method to recover silver, copper and lead from copper anode slime by carbothermal reduction and super-gravity

In the present study, an effective and green method to recover silver, copper and lead from copper anode slime by carbothermal reduction and super-gravity separation was investigated. During the pretreatment process, 99.9% of selenium was removed from copper anode slime after sulphation roasting, and the valuable metals of lead, copper and silver were concentrated as the lead-silver-copper multiphase complex by carbothermal reduction. The influence of temperature on the reduction efficiency was studied and the results obtained were supported by thermodynamic analysis. Under the optimal super-gravity separation conditions of G = 600, T = 1423 K and t = 5 min, the filtrated lead-silver-copper multiphase complex and residual phases were obtained. Results showed that the yield of the filtrated Pb-Ag-Cu phase was about 83% and the recovery efficiencies of lead, silver and copper exceeded 98%, 96% and 89%, respectively. These residues could be recycled to the pretreatment processes. Finally, based on the phase diagram analysis and equilibrium calculations, the lead-silver and copper-silver phases can be obtained and this was demonstrated after super-gravity enrichment. This work confirmed that super-gravity technology was a feasible approach in the recovery of valuable metals from copper anode slime due to its significant advantages of high efficiency, simple operation, and being more environmentally-friendly.