Evolution of Group 15 Elements in Electrolyte during Laboratory Electrorefining of Primary Copper Anodes

Three primary copper anodes obtained from commercial operations were used to conduct laboratory scale electrorefining experiments. The purpose of these experiments was to study the deportment of arsenic, antimony, and bismuth from the anodes to the electrolyte and slimes. The concentrations of As, Bi, and Sb were monitored in a recirculating electrolyte over multiple months. Using mass balance calculations, the deportment of these elements was assessed. An anode with a molar ratio of As/(Sb+Bi) of 0.27 resulted in tube clogging and experimental difficulties. An anode rich in bismuth with a As/(Sb+Bi) molar ratio of 2.94 achieved supersaturation and then precipitation of BiAsO 4 . All three anodes experienced declines in antimony concentration to lower values as compared to commercial electrolytes, agreeing with previous observations regarding synthetic electrolytes. The formation of arsenato antimonic acid and the precipitation of arsenato antimonates is hypothesized to account for the decrease in antimony concentration with time. Complex oxidative phase slime particles rich in antimony and arsenic were observed in all three anodes’ slimes. This laboratory data further explores the complex behaviors of the Group 15 elements during dissolution and slimes formation in copper electrorefining.