Research On Novel Ultrasonic And Microwave Assisted Pretreatment Of Copper Anode Slime With High Lead Content

Copper anode slime is an important by-product in the process of copper electrolytic refining, which contains large amounts of precious metals and rare metals, thus it becomes an important source of extracting rare and precious metals materials.The study was based on the raw material of copper anode slime with high lead content. Atmospheric pressure acid leaching, ultrasonic-assisted acid leaching and microwave-assisted acid leaching pretreatment were carried out respectively, with their dynamics analyzed. The optimal pretreatment process was determined by comparing the leaching efficiencies of copper, selenium and tellurium in each process.Test results show that, the optimal conditions of atmospheric pressure acid leaching pretreatment process were:acid concentration 1.0 mol-L-1, leaching temperature 80 ℃, solid-liquid ratio 0.20 g·mL-1, leaching time 90 min, ventilation rate 0.3 L·min-1 and concentration of hydrogen peroxide 0.2 mol·L-1. Under the optimal conditions, the leaching efficiencies of copper, selenium and tellurium were 95.63%,15.33% and 30.78%, respectively. The apparent activation energy of atmospheric pressure acid leaching was 54.55 kJ·mol-1, which was controlled by chemical reaction.The optimal conditions of ultrasonic-assisted acid leaching pretreatment process were: ultrasonic power 500 W, leaching time 90 min, leaching temperature 80℃, solid-liquid ratio 0.25 g·mL-1, acid concentration 1.0 mol·L-1 and concentration of hydrogen peroxide 0.3 mol·L-1. Under the optimal conditions, the leaching efficiencies of copper, selenium and tellurium were 97.13%,34.23% and 43.98%, respectively. The apparent activation energy of ultrasonic-assisted acid leaching was 41.62 kJ·mol-1, it shows that ultrasound-assisted acid leaching can reduce the activation energy of the reaction, which makes reaction easier, and promotes the leaching of copper, selenium, tellurium further.The optimal conditions of microwave-assisted acid leaching pretreatment process were: microwave power 700 W, leaching time 40 min, solid-liquid ratio 0.30 g·mL-1, acid concentration 1.5 mol·L-1, concentration of hydrogen peroxide 0.4 mol·L-1 and target temperature 90℃. Under the optimal conditions, the leaching efficiencies of copper, selenium and tellurium were 99.37%,76.12% and 77.38%, respectively. The apparent activation energy of ultrasonic-assisted acid leaching was 53.49 kJ·mol-1, which shows that microwave heats system simply and does not change the activation energy.Microwave-assisted acid leaching has many advantages, such as high efficiency, large capacity and less pollution. Moreover, the leaching efficiencies of selenium and tellurium increase significantly. Therefore, microwave-assisted acid leaching is the optimal pretreatment process.