Study on the relation between passivation behavior and microstructure of copper anode: Cu-O-S-Vb (As, Sb, or Bi) system

This study has investigated the microstructures of copper anodes of quaternary systems, i.e., Cu-O-S-Vb element (As, Sb or Bi), at several different levels of oxygen, sulfur and an impurity element and their reductive effects on passivation behavior during the electrorefining process. The results show that by the addition of a Vb element and subsequent compound formation at grain boundaries, one of the causes of passivation has been eliminated, by decreasing the eutectic area from the anode surface. This result gives an indication that passivation may be reduced, thus making a higher current density operation possible, by properly controlling the impure element content levels matched by oxygen and sulfur contents.