The Chemical Purification Of Copper Electrolyte Technology

With the rapid development of copper smelting industry, the circumstances of copper concentrate resources are in short supply in China becomes increasingly evident, which induce the increase of impurities in raw material and especially the critical accumulation of arsenic, antimony and bismuth in the electrolytes. This work aims to search a novel technology with fine purification performance, low cost and convenient technique in purification for the copper electrolytes.The technological conditions of evaporation crystallization of copper electrolyte to separate copper was studied. When the amount of evaporation of copper electrolyte(800mL) is 380mL, the concentration of sulfuric acid is 295 g·L-1 and the cooling temperature is 20℃, the removal rate of CuSO4 is 58.79%, and the concentration of As and Sb in the electrolyte crystallized respectively are 15.38 g·L-1 and 0.64 g·L-1.Impurities were removed when hypophosiphite was added into copper electrolyte. The removal rates of Cu, As, Bi are 40.7%,26% and 50.4% respectively when the volume ratio of hydrochloric acid to electrolyte is 9:300, the dosage of hypophosiphite to electrolyet is 12g:300ml, the the concentration of copper ion is 22 g·L-1, the concentration of sulfuric acid is 530 g·L-1, the reaction temperature is 60℃and the reaction time is 6h. There were Cu2Cl2 and CuSO4·5H2O in the precipitate. But antimony and bismuth were not removed when hypophosiphite was added into copper electrolyte.Impurities, such as arsenic, antimony and bismuth were removed when hydrazine hydrate was added into copper electrolyte. The removal rates of Cu, As, Sb and Bi are 97.04%,5.28%,37.92%and 94.40% respectively when the volume ratio of hydrazine hydrate to electrolyte is 1:20, copper ion is 22 g·L-1, sulfuric acid is 203 g·L-1, the reaction temperature is 42℃, the reaction time is 1h and As, Sb and Bi were 8.80 g·L-1,0.36 g·L-1,0.20 g·L-1 respectively. The removal rate of As increase under the action of halide. There were Cu4SO4(OH)6·H2O, Cu2(OH)3NO3 and Cu3(AsO4)(OH)3 in the precipitate after hydrazine hydrate was added into copper electrolyte. Under the above conditions, the copper sulfate solution can be purified up to the requirements of the industrial practice in the copper plant.