Processing of copper dust for tolerable iron containing electrolyte

Copper dust from the Indian Copper Complex, Ghatsila is water leached and the residue is subjected to leaching by sulphuric acid solution. Effects of various parameters on H2SO4 leachings of water leached residue (WLR) and as received copper dust have been investigated to obtain optimum conditions for leaching. Under optimum conditions, bulk leachings of WLR and as received copper dust by H2SO4 solutions have been carried out. Leaching of 150 g WLR by 1 dm3 of 15% (v/v) H2SO4 at 353 K for 4 h under reflux yields 1 dm3 leached solution containing 43·12, 16·20, 22·14, 0·40, 0·02, 0·04 and 0·12 g dm−3 Cu2+, Fe2+, Fe3+, Zn2+, Co2+, Ni2+ and Al3+ respectively, together with 0·90M unreacted H2SO4. Also, leaching of 160 g as received copper dust by 1 dm3 of 10% (v/v) H2SO4 at 353 K for 4 h under reflux yields a leach solution containing 44·30, 9·00, 15·70, 0·40, 0·15, 0·03 and 0·11 g dm−3 Cu2+, Fe2+, Fe3+, Zn2+, Co2+, Ni2+ and Al3+ respectively, together with 0·90M free H2SO4. The iron contents of these solutions have been reduced to the levels of <0·5 g dm−3 by applying D2EHPA extraction–oxalic acid stripping technique so that the solutions can be used as electrolytes in electrorefining, electrowinning or hydrogen reduction of copper.