Recycling process of nickel,copper and chromium from the electroplating sludge

The electroplating sludge was treated for the comprehensive recovery of copper, chromium and nickel with procedures including sulfuric acid leaching, copper precipitation, chromium removal by two-stage neutralization, and nickel carbonate concentrating. Various processing factors were studied and the optimum conditions were obtained as follows:0.5 h, 50℃, and 0. 8 times of stoichiometric sulfuric acid addition for sulfuric acid leaching; 1 h, 85℃, and 1.2 times of stoichiometric copper precipitator addition for copper precipitation; the two-stage chromium removal method decreases nickel loss in the precipitation process. More than 98% of copper, 99% of chromium and 94% of nickel originally contained in the sludge were successfully recovered by using this process.