Abstract
A high current density operation is desired to improve the productivity in copper electrorefining. It is known that an agitation of the electrolyte has a potential to overcome the problems such as the passivation of anode and dendritic deposition at cathode in the high current density operation. In this paper, effects of the fluid motion on the behaviors of arsenic, antimony and bismuth were investigated under high current density conditions. The concentrations of impurities in the deposition increased with increasing the current density without the forced convection. An increase in the fluid velocity suppressed the increase in impurity concentrations. The impurity concentrations were high especially in the initial stage of the deposition without the forced convection. It corresponded to the decrease in the cathode potential measured in the period. It means that the enrichment of impurities was induced electrochemically. The reason of the decrease in the cathode potential was low concentration of the copper ion on the electrode surface due to the consumption of the ion with the electrolysis. The forced convection of the electrolyte enhanced the ionic mass tranfer and thus suppressed the polarization and deposition of the impurities. It was made clear that the fluid motion is effective for the achievement of the electrolysis under the high current density.
