Effects of Acid Pretreatment on Purity of Copper Foil Recovered by Electrolytic Refining from Waste Printed Circuit Board

In order to extend the duration of the electrolyte solution in which copper granules recovered from waste printed circuit board are refined through electrolysis to obtain copper foil with high purity and which is contaminated by the accumulation of metallic impurities along with the refinery of waste printed circuit board, the leaching and electrowinning processes are used to pretreat the copper granules. The effects of impurities of copper granules as well as H 2 SO 4 mole ratio, leaching temperature, liquid-solid ratio, and operation time on the removing efficiencies of Zn, Sn, Fe and Al, were studied. The results showed that more than 95% of impurities can be removed when the mole ratio of impurities to H 2 SO 4 was 1:4, the temperature was 70 °C, the liquid-solid ratio was 20 mL/g, along with the leaching time of 180 min. After 1440 min electrolysis of the pretreated granules with the electric current density of 40 mA/cm 2 , the purity of refined copper foil maintained at 99% in contrast with 95% which copper granules are without pretreatment. The maximal concentration of the accumulated ions of impurities is less than 60 mg/L, which suggests that sulfuric acidic pretreatment is a promising approach to increase the duration of the electrolyte solution.