A New Process of Chlorine Deep Removal in Zinc Sulfate by Highly Active Copper from Copper Slag

Chloride concentration is one of the important factors that seriously affect the electrolysis of zinc sulfate. The copper slag used in the copper slag dechlorination method has low activity due to long-term storage, resulting in an unstable dechlorination effect. Therefore, a highly active copper deep dechlorination process is proposed to achieve the purpose of stable and deep dechlorination. In this study, the copper slag was pre-oxidized, and high-activity copper was obtained by adding an appropriate amount of zinc powder. The experimental results show that the dechlorination rate reaches 90.41% when the initial solution acidity is 30 g/L and the ratio of copper slag to zinc powder is 7:6; the solution was treated at room temperature (20°C) for 30 min. When the amount of zinc powder was increased 8 times, the removal of chloride ions reached 95.43% and the content of chloride ions in the solution was reduced to 20 mg/L. The dechlorination effect is much lower than the standard of chlorine (< 100 mg/L) in the zinc electrolysis process, realizing deep dechlorination. The process ensures the smooth progress of zinc electrolysis and has great application prospects.