Abstract:Cu, As, Sb and Bi in copper electrolyte could be efficiently removed by reducing with SO₂ followed by evaporative crystallization. As₂O₃ and CuSO₄·5H₂O were obtained after crystallized product was treated by dissolution, oxidation, neutralization, sedimentation, filtration and evaporative crystallization. The removal rates of Cu, As, Sb and Bi are 87.1%, 83.9%, 21.0% and 84.7%, respectively, when As (V) in copper electrolyte is fully reduced to As (III) by SO₂, and the H₂SO₄ in concentrated copper electrolyte is 645 g/L. The removal rate of As is 92.81% when 65 g crystallized product is dissolved in 200 mL water at 30 °C. The CuSO₄·5H₂O content is 98.8% when the filtrate is purified under the conditions that n(Fe):n(As) is 1.2, the dosage of H₂O₂ is 19 times the stoichiometric needed, temperature is 45 °C, time is 40 min, pH is 3.7, and then is evaporation crystallized.

Key words: copper electrolyte; sulfur dioxide; purification; copper sulfate; arsenic trioxide