Selective separation and recovery of selenium from copper anode slime by compound leaching followed by sulfate roasting

Abstract

In this research, selenium was selectively separated and recovered from copper anode slime by a hydrometallurgical-pyrometallurgy union process. In the first compound leaching process with H2SO4, HCl and NaCl media, the pre-removal of As, Sb, and Bi was achieved, and the removal efficiencies were 85 %, 83 %, and 91 %, respectively. Selenium was effectively enriched by approximately 200 % after first compound leaching. Sulfate roasting method was used to selectively separate selenium in the second stage. In this study, more than 99.39 % of selenium was separated with concentrated sulfuric acid amount to first leaching residues ratio (H2SO4/ first compound leaching residues ratio) of 0.30 mL/g at 500 °C for 25 min, which enabled selenium to be selectively separated from the other elements. The kinetics of sulfation roasting of Se-enriched residues show that the selective separation of selenium conforms to the Avrami multiphase liquid–solid region reaction, the activation energy of the reaction is 28.118 kJ/mol, and the reaction efficiencies equation is k = 3.607e-3382/T, indicating that it is internal diffusion-controlled.