Electrowinning copper from solvent extraction acid strip solution using Pb-Sb anodes

Abstract

Copper electrowinning from solvent extraction acid strip solutions was studied as a part of a more comprehensive laboratory investigation on development of a process for treating native copper ores by ammoniacal leaching-solvent extraction-electrowinning methods. Because initial electrowinning tests resulted in poor quality copper cathodes, a study was undertaken to determine the conditions necessary for producing high-quality electrowon copper before proceeding with other phases of the process development. The electrowinning tests showed that removing entrained organic from the electrolyte, maintaining a protective voltage on the anodes when electrowinning was not in progress, and adding a small amount of cobalt to the electrolyte resulted in production of copper cathodes with a low lead content when using antimonial lead anodes. After satisfying these conditions, large variations in other operating conditions were possible without materially affecting the lead content of the electrowon copper. Copper cathodes with lead contents of less than 2 ppm were consistently produced. These results were obtained with laboratory-scale equipment and quantitative extrapolation to industrial-scale operations may not be valid. However, the qualitative effects of the various processing conditions should be applicable to industrial electrowinning.