Leaching behavior and occurrence of metal elements in copper slag: The key to recycling metals in copper slag

Abstract

Recovering of metals from Copper Slag (CS) is important to alleviate the resource shortage of metals and eliminate environmental pollution. Thus, this study aimed to propose information on leaching behavior and a full image of CS's main element occurrence phases in order to further improve the efficiency of metal recovery. The pH-dependent leaching experiments with the help of geochemical modeling showed that 99.66 % undissolved Fe exists in fayalite, magnetite, and calcium-iron silicates, and 97.14 % undissolved Zn exists in fayalite and sphalerite. The mineral liberation analysis (MLA) results confirm that 80.92 % Fe and 83.75 % Zn are present in fayalite. It was found that 52.71 % calcium-iron silicate and 65.60 % iron oxide were associated with fayalite, so in the future, the recovery of Fe and Zn should not only target fayalite but also pay attention to the influence of calcium-iron silicate and iron oxide on the recovery. At the same time, when leaching elements such as Fe and Zn from fayalite in CS, the environmental risks associated with the subsequent leaching of Pb should be considered. Overall, the results of this study provide comprehensive information on the leaching behavior of significant metal elements and the associated mineral characterization of CS and thus, provide the basis for the metal recovery of CS in the future.