Effect of SO2 & air sparging in electrowinning of copper

Abstract

Electrodeposition of copper was carried out in an acidic medium with compressed air and SO, in an electrolytic cell with continuous solution flow. The effect of copper, sulfuric acid and ferrous iron concentrations in the electrolyte on the nature of the deposit, current efficiency, and cell voltage were investigated. Copper concentration was varied from 5 to 50 g/L, sulfuric acid, 0 to 200 g/L and ferrous iron from 0 to 10 g/L. Current density was varied from 100 to 300 A/m(2). Cell voltage was reduced by about 0.2 V in the case of copper variation and about 1.0 V in the case of sulfuric acid variation. With increase of current density from 100 to 300 A/m(2), cell voltage increased by 0.4 V. With increase of ferrous iron, however, there was scarcely any change in cell voltage up to 5 g/L, but marked difference was observed at 10 g/L. At a current density of 300 A/m(2), the reduction in cell voltage was 0.25 V because of the presence of sulfur dioxide and air. The deposit morphology is compared on the basis of SEM photographs.