Mechanism and kinetics of synergistic decopperization from copper anode slime by ultrasound and ozone

Abstract

Copper anode slime is a typical hazardous waste that is rich in precious metals, rare metals and other valuable metals. Decopperization is the first step to recycle rare and precious metals from copper anode slime. In this work, the synergistic effect of ultrasound and ozone on copper leaching from copper anode slime was studied to develop an efficient and clean decopperization process. The effects of the reaction time, temperature, initial sulfuric acid concentration, ultrasound power and ozone flow rate were investigated. The results show that the dissolution fraction of copper can reach 98.46% under the optimum ultrasound and ozone reaction conditions. However, the leaching efficiency of copper under ozone is only 50.99% at 30 min. The kinetics analysis shows that the leaching reaction follows the classical unreacted-core shrinking model. The apparent Ea value and reaction orders were estimated to be 10.37 kJ/mol and 0.34, respectively. Meanwhile, the leaching kinetic equation under ultrasound and ozone was established using quadratic regression. Surface analyses indicated that the copper compound leached under ultrasound and ozone exposure. The higher leaching efficiency of copper results because copper and its compounds are transformed into soluble copper sulfate under the combination of ozone and ultrasound. The concentration of precious metals in the leaching residue under ultrasound and ozone is the highest, indicating that the synergistic effect of ultrasound and ozone can effectively enrich valuable precious metals. Synergistic decopperization from copper anode slime by ultrasound and ozone offers wide application prospects in transforming harmful anode slime waste into valuable materials.