Dissolution behavior and kinetics of copper slag under oxidative conditions

Abstract

This study investigates the extraction and leaching kinetics of metals from slag, a by-product in pyrometallurgical copper production, under atmospheric leaching conditions in the presence of HCl-H2O2.The optimum leaching conditions were determined as follows: 0.1M HCl concentration, 3M H2O2 concentration, 60minutes leaching time, 318K leaching temperature, 400rpm stirring speed, and 25:1 liquid-solid ratio. Under these conditions, 76% Cu, 2.8% Fe, and 23.6% Zn were successfully extracted. The selection of these optimum conditions aimed to achieve a selective leaching outcome by considering the Cu/Fe ratio.The leaching kinetics were found to be in agreement with a mixed control model based on reactant concentrations, as described by the equation (15(1−∝)−53−141−∝−43+120=kt). The shrinking core model was used to represent the leaching process. The activation energy was determined to be 55.35kJ/mol, and the reaction degree with respect to H2O2 and HCl was found to be 0.90 and 0.58, respectively.SEM-EDX, XRD, and particle size analysis were conducted on the leach residue. The results revealed the presence of Fe2SiO4 and Mg0.2Fe2.6Al0.2O4 phases in the leach balance, while the particle size was determined to be D(50)= 52.5µm.