Effect of Aqueous Antimony Species on Corrosion of Pb­Sn­Ca Alloy in Copper Electrowinning

Copper electrowinning is a crucial process for producing primary copper from copper oxide minerals and for recycling copper through smelting, leaching, and electrowinning. This study investigates the effect of aqueous antimony species on the corrosion of a Pb­Sn­Ca alloy in copper electrowinning using galvanostatic electrolysis, X-ray diffractometry, scanning electron microscopy-energy dispersive X-ray spectroscopy, and inductively coupled plasma-optical emission spectrometry analyses. Conducted at varying current densities in a synthetic copper electrolyte at 65°C, the results indicate that without antimony species, the anode surface is covered with a slow-growing PbO2 scale. In contrast, the presence of Sb(III) leads to the formation of a laminated Sb2O5-PbO2 scale on the anode surface, which grows significantly faster. Subsequently, flakes from this scale detach, thereby accelerating the corrosion of the Pb­Sn­Ca alloy anode. The oxidation of Sb(III) to Sb2O5 is primarily due to an anode reaction rather than interaction with oxygen on the anode surface. The presence of Sb2O5 in the copper electrolyte results in a considerable decrease in aqueous antimony, proving effective for enhancing electrowinning processes aimed at producing pure copper cathodes and reducing antimony levels in the electrolyte.