Selective and Multi-Step Leaching of Valuable Metals from Scrap Copper-Smelting Sludge

Abstract

Valuable metals in smelting sludge from smelting industry have a recovery value. In this work, for realizing waste recycling effectively, selective and multi-step leaching of valuable metals was investigated with scrap copper-smelting sludge as research object. The effect of the concentration of sulphuric acid on leaching rates of valuable metals was investigated first. The results showed that the leaching rates of Cu, Zn and Ni were 6.1%, 59.4% and 63.3% at the acid concentration of 65g/L. Then, the results of the selective and multi-step leaching indicated that the leaching rates of Cu, Zn and Ni were over 90% after two-step leaching. In third step, the content of Cu in leached residue was 6.68%, which was higher than origin sludge. Repeat three-step leaching process above, Zn and Ni were leached selectively and Cu was accumulated in leached residue continually.