Sequential leaching of copper from mill tailings with aqueous solutions of hydrochloric acid and sodium hypochlorite

This work presents an investigation of kinetics of copper leaching from mill tailings with hydrochloric acid and sodium hypochlorite at room temperature in filtration mode. The concentration of hydrochloric acid and sodium hypochlorite varied from 0.05 to 0.5 M and 0.025 to 0.1 M respectively. When the samples were leached in the sequence of five-hour leaching with solutions of hydrochloric acid, and then six-hour with sodium hypochlorite, the maximum degree of copper extraction into the solution was 32.62 %. And in case of leaching samples in the inverse direction, with a solution of sodium hypochlorite for two hours, and then with hydrochloric acid for seven hours, 87.10 % of copper was extracted, which is 2.67 times more than in the previous case. It has been shown that the sequence of using reagents in leaching has a significant impact on the efficiency of copper extraction from the tailings