The Role of Lead in Suppressing Passivation of High Silver―Containing Copper Anodes During Electrorefining

Passivation behavior of high silver containing copper anodes was investigated using slowly cooled Cu- 1%Ag different lead (Pb) concentrations. The addition Pb distributes in the phase and reduces amount that is solidly soluble and, thus, generates a fine powder on anode surface which main contributing factor passivation. Electrorefining experiments were conducted synthetic electrolyte 40 g/L Cu2+ 180 H2SO4, at 60°C. SEM-EDS analysis used to study resulting slime showed increasing content altered structure from compact porous less adherent surface. Utilizing Cu-1%Ag0.2%Pb yielded longest passivation time with low stable cell voltage 0.1V. morphology characterized by precipitated metallic particles either as inclusion or loosely present abundant complex Cu-Ag-Pb sulfate type compounds. Because economic importance recovery slime, understanding its during electrorefining will enable operating impurity especially secondary processing where impurities can result e-waste alloy scrap.