Deep Electrochemical Purification of High Arsenic-Bearing Copper Refined Electrolyte

Traditional electro-deposition techniques turn out ineffective in removing excessive arsenic (As) impurities and may result in the disqualification of high-purity copper (Cu) products while dealing with high As-bearing Cu electrolytes. This study focused on the following two aspects: First, the cryogenic cooling crystallization and acid supplementation for purified copper were investigated; second, the factors affecting the removal of As impurities from the electrolyte were studied in combination with electrolysis at the optimal copper-to-arsenic mass concentration (Cu/As) ratio. Below are the optimal conditions determined for electrolysis of As, with Cu as the cathode material: The Cu/As ratio of the electrolyte can be lowered to 0.25 by increasing the acid concentration to 370 g/l and crystallizing Cu precipitation by cooling down to 10 °C. During electrolysis, optimal Cu/As ratio of 0.01–0.05, sulfuric acid (H 2 SO 4 ) concentration of 230 g/l, and current density of 500 A/m 2 , the maximum removal rate of arsenic is up to 45%, the Cu-As alloy gradually took shape, with the main species being Cu 3 As, achieving high efficiency arsenic removal. A cryogenic crystallization and Cu reduction procedure was proposed coupled with multipoint feeding electrorefining and As removal. Graphical Abstract