Synergistic mechanism and decopperization kinetics for copper anode slime via an integrated ultrasound-sodium persulfate process

Abstract

An eco-friendly synergistic decopperization method via ultrasound and sodium persulfate was developed from copper anode slime (CAS), a hazardous solid waste. The advanced oxidation process was applied to the field of metal leaching/enrichment in hydrometallurgy. Electron paramagnetic resonance (EPR) spectroscopy was used to trace the free-radical quenching mechanism in the leaching experiment. The influence of different conditions on copper leaching efficiency was studied. A total of 98.11% of copper was removed by the synergistic process from CAS. By comparison, the leaching efficiency of copper by persulfate leaching under the same conditions was only 66.64%. The kinetics model fitting results indicate that ultrasound reduced the threshold of the leaching reaction. The leaching reaction order values of the H2SO4 and Na2S2O8 concentrations are 0.11 and 0.69, respectively, which shows that persulfate plays a major role in leaching efficiency in the decopperization process. Mineralogical analysis demonstrated that the insoluble copper was effectively transformed into copper sulfate via ultrasound and sodium persulfate. In addition, hazardous solid waste was converted to valuable high-grade metallurgical stock through the enrichment of rare noble metals in CAS using a cooperative process. The novel decopperization method via integrated ultrasound/sodium persulfate has wide application prospects in waste management and recycling in a clean and economical hydrometallurgical process.