Separation and recovery of arsenic from As, Cu, and Zn rich leaching liquor using a reduction-crystallization approach

Abstract

As, Cu, and Zn rich leaching liquor is generated in the leaching process of copper dust, which contains various metals with high recovery value. Herein, an approach for the direct separation and recovery of arsenic from As, Cu, and Zn rich leaching liquor was proposed. The approach includes two steps, namely SO₂ reduction and arsenic crystallization. The factors affecting the reduction of As(V) to As(III) were investigated, including the pH, SO₂ dosage, and reduction temperature. In the crystallization stage, the impacts of sulfuric acid consumption and temperature on the crystallization of arsenic (As₂O₃) were studied. The results show that the optimal H⁺ concentration, temperature, and SO₂ input for the arsenic reduction were 3.95 mol L⁻¹, 45 °C, and 1.14 L g⁻¹ As(V), respectively. While the optimal temperature and sulfuric acid dosage in As recovery process were 5 °C and 0.1 L L⁻¹ leaching liquor, respectively. Under these conditions, the As₂O₃ recovery percentage reached 96.53%, and the losses of Cu and Zn were only 3.12% and 0.75%, respectively. The precipitate contained 96.72% of As₂O₃, 0.83% of Cu, and 0.13% Zn. Compared with the traditional technologies, this new method can improve the recovery efficiency of As₂O₃ and reduce the loss percentage of other valuable metals (Cu and Zn).