Experimental analysis of the performance of innovative circulation configurations for cleaner copper electrolysis

Abstract A series of copper electrorefining tests were performed to determine the effects of circulation configuration, as well as inlet flow rate and current density, on impurity particle behavior and cathode purity. SEM/EDS was utilized to acquire surface characteristics and impurity distributions on the harvested cathode copper and the collected anode slimes. The anode slime weight distributions under different operating conditions were analyzed to determine the effects of the three factors on anode slime behavior. ICP was used to obtain the concentrations of major impurities in the harvested cathode copper, and the results of selected impurities (As, Sb, Bi) were statistically analyzed to determine the relationship between the factors and impurities concentrations. The circulation configuration was identified as the most significant factor based on the statistical results, with the innovative configuration of two upper-inlets/one lower-outlet as the optimal configuration. Furthermore, a theoretical discussion of the effects of these factors on slime particle behavior is given, which demonstrates that these factors have significant impact on slime particle transport by influencing species distribution, electrolyte density gradient, and fluid flow field in the cell. In addition, SEM/EDS results of collected slimes show that the innovative circulation configurations have the advantage of converting more suspended slime particles to settled slimes.