A Multistage Process for Copper and Gold Leaching from “Dust Unit of Sarcheshmeh Copper Complex” Residue

This paper presents a novel multistage hydrometallurgical process for copper and gold leaching from Sarcheshmeh Copper Complex (in Kerman, Iran) dust unit residue. To this end, 95.4% of copper and 90.2% of iron were leached in a three-step process using sulfuric acid in the presence of hydrogen peroxide, as the pretreatment. The solid residue from sulfuric acid pretreatment was applied to extract gold into the solution using acidic Thiourea leaching. To better understand the influence of different parameters on gold leaching using Thiourea and to reach maximum extraction, central composite design (CCD) was used through response surface methodology (RSM). The optimum conditions for gold leaching are as follows: Thiourea concentration = 20 g/L; temperature of leaching = 80 ˚C; and leaching time = 8 h. Under these conditions, the experimental leaching efficiency of gold was 44.2%. The presented mathematical model in the current study well explained the experimental data with the correlation coefficient value of 92.11% (R^2).