Solvent extraction of copper from zinc sulphate leach solutions using LIX 622 and the effect of organic contamination on zinc electrowinning

摘要

A study has been carried out on the use of solvent extraction, instead of the traditional zinc dust cementation process, to remove copper from concentrated zinc sulphate leach solutions. In a series of experiments using plant solution containing1.9 g/L Cu, 2 g/L Fe, 173 g/L Zn, 7.9 g/L H{sub}2SO{sub}4, 0.25 g/L Cd, 15 mg/L Co etc. and LIX 622 in SX-1, upto about 97-98 % of copper present in the zinc sulphate leach solution was extracted with negligible co-extractions of zinc, iron, cadmium,cobalt, etc. pH modification was not required for this reagent. The copper loaded organic was almost completely stripped using 150 g/L sulphuric acid. Investigations into the effect of any possible organic/extractant contamination on zinc electrowinningshowed (if any) little effect on current efficiency if the organic contamination is less than 45 ppm; current efficiencies of 95-97 % were obtained. At organic contaminations higher than 45 ppm, the current efficiency dropped to about 92-94 %. Visually,the organic-contaminated cathode sheets had rough surface morphology, becoming more intense with increasing organic concentration, compared to the non-contaminated cathode sheets.