EFFECT OF IMPURE ELEMENTS ON THE STRUCTURES OF SOLIDIFIED COPPER ANODES AND PASSIVATION BEHAVIOR DURING ELECTROREFINING - Cu-O-Vb(As, Sb or Bi SYSTEM AND Cu-S-Vb SYSTEM.

In order to investigate the effect of impure elements on the anode passivation behavior during electro-refining process, a relationship between passivation phenomena and solidified structures of synthetic ternary copper anodes, i. e. Cu-O-Vb element (As, Sb or Bi) system and Cu-S-Vb element system, has been investigated. Passivation behavior has been quantified by the passivation time under a certain electro-refining condition. The results obtained have shown that these ternary copper anodes containing two kinds of impure elements (such as oxygen plus one of Vb elements) at around stoichiometric composition ratio for compound formation have the microstructures of least eutectics and the compound tends to precipitate at grain boundaries. It has also shown that such ternary copper anodes exhibit the least tendencies for passivation. A further discussion for this relationship between passivation and microstructures has also been presented.