Investigation of an alternative chemical agent to recover valuable metals from anode slime

Anode slime (AS) including high content of precious metals is a by-product obtained after the electro-refining stage in copper production. In this study, it is aimed to recover Cu, Au, and Ag from the AS by using 1-butyl-3-methyl-imidazolium hydrogen sulphate ([Bmim]HSO₄) ionic liquid (IL) as a green solvent. The effects of IL concentration, temperature, reaction time and pulp density on recovery of valuable metals were statistically investigated. A high copper recovery of 87.52% was obtained under optimum condition as in 60% (v/v) [Bmim]HSO₄ at 50 °C after 2 h, pulp density at 40 g/L (1/25 solid/liquid ratio). Also, a remarkable gold recovery as 97.32% has been achieved in 80% (v/v) [Bmim]HSO₄ at 95 °C after 4 h, pulp density at 40 g/L. Temperature and IL concentration were detected as the most effective parameters for copper and gold recovery from AS, respectively. Silver could not be recovered from the AS due to the lower solubility in [Bmim]HSO₄ IL media. According to experimental results, [Bmim]HSO₄ could be offered as an alternative leaching agent, instead of conventional solvents, to recover valuable metals from copper anode slime.