Ž . Hydrometallurgy 59 2001 55–67 www.elsevier.nlrlocaterhydromet Electrowinning of copper from sulfate electrolyte in presence of sulfurous acid B. Panda, S.C. Das ) Council of Scientific and Industrial Research, Regional Research Laboratory, Bhubaneswar 751 013, Orissa, India Received 16 January 2000; received in revised form 21 July 2000; accepted 27 July 2000 Abstract The electrowinning of copper from acidic sulfate solution in the presence of sulfurous acid using a graphite anode was investigated. The effects of operating variables including sulfur dioxide concentration, copper concentration, sulfuric acid concentration, current density and temperature on the cell voltage, anode potential, power consumption, current efficiency, deposit quality, surface morphology, crystallographic orientations and polarisation characteristics were studied. Other anode materials such as PbrSb, PbrAg, Ti and Ti–IrO were also used to examine their effects on electrocatalytic activity for 2 oxidation of SO and deposit quality. A rectangular stainless steel cathode of length 8 cm, width 5 cm and thickness 2 mm 2 was used for copper electrowinning. Increases in SO concentration, copper concentration, sulfuric acid concentration and 2 temperature lower the power consumption. These variables have no effect on the current efficiency of copper deposition. The presence of SO in the copper electrolyte affects both the cathodic and anodic polarisation curves. In addition, it causes 2 Ž .Ž .Ž .Ž . Ž .Ž .Ž .Ž . shifting of preferred orientations from 220 111 200 311 to 111 200 220 311 . Changes in crystallographic orientation are also seen in the surface morphology of deposited copper. It is found that minimum power consumption together with maximum current efficiency and improved surface morphology can be achieved using a graphite anode. q 2001 Elsevier Science B.V. All rights reserved. Keywords: Electrowinning; Copper; Sulfate electrolyte 1. Introduction Copper extraction has undergone many develop- ments in the past 20 years. Both pyro- and hydromet- allurgical processes have been improved and totally ) Corresponding author. Tel.: q 91-674-581750; fax: q 91-674- 581750. Ž . E-mail address: director@csrrlbhu.ren.mc.in S.C. Das . wx new processes have been reported 1 . The techno- economic problem associated with the SO 2 emissions from copper smelting in pyrometallurgical processes has prompted the development of hy- drometallurgical processes for recovery of copper from sulfide concentrates. The unit operations gener- ally involved in these hydrometallurgical processes are roasting, leaching and electrowinning. In recent years, there has been a marked increase in the pro- duction of copper by electrowinning. A major draw- back is the high energy requirement associated with 0304-386Xr01r$ - see front matter q 2001 Elsevier Science B.V. All rights reserved. Ž . PII: S0304-386X 00 00140-7