Leaching and recovery of selenium from Sar-cheshmeh copper anode slimes

Leaching and recovery parameters controlling the releasing of selenium from Sar-Cheshmeh copper anode slimes are studied and determined.

Copper anode slimes is produced during the production of cathodic copper at the bottom of electrolyte cells, which is composed of insoluble anode components in the electrolyte. The copper anode slimes are made up of those components of the anodes, which are not soluble in the electrolyte. They contain varying quantities of precious metals like gold, silver, selenium and tellurium, and other precious metals in the anodic copper. They are being extracted as a by-product in the copper production process. Due to the fact that the main source of selenium is sulfur deposits such as copper and nickel. Copper anodic slimes is currently the only source of selenium in the world. In this study, the extraction of selenium from anodic copper slimes has been feasible. To do this, acid leaching has been used. Copper anodic sludge is the raw material for the production of more than 90% of the world selenium and is the main source of selenium production.[1-3]

In this paper, the effect of operational parameters such as acid concentration, temperature, process time and liquid to solid ratio on selenium recovery through copper slimes leaching was investigated. The optimum conditions of batch leaching For maximum selenium extraction from anodic copper slimes are attained at 3 mol L-1 of HNO3 concentration, 0.01 (W/V) solid to liquid ratio for 60 min contact time at 70 º C. Under the optimized conditions, the selenium leaching efficiency was 99%. The thermodynamic data showed positive values of both ΔH and ΔS which indicates that the leaching process is indeed endothermic and random while the obtained negative values of ΔG show that selenium dissolution process is spontaneous in nature.