Retention of Arsenic During the Roasting Process of Antimony Sulfide Concentrate: Alleviate Environmental Pollution Caused by Arsenic-Alkali Residue

Arsenic is removed in the refining process of crude antimony in traditional antimony smelting, which produces a lot of arsenic-alkali-residue (AAR). This study proposes a two-stage roasting process to retain arsenic during volatile roasting of antimony sulfide concentrates. Calcium oxide was employed to retain arsenic in the calcine at low temperature, while antimony was volatilized into the fume as antimony trioxide at high temperature. The feasibility was verified by thermodynamic calculations. The effects of different factors on the volatilization efficiency of antimony and the retention efficiency of arsenic were investigated. Moreover, the leaching toxicity of arsenical calcine was tested. The volatilization efficiency of antimony and retention efficiency of arsenic were 93.06 and 70.12 pct at optimized conditions, respectively. The leaching concentration of arsenic in the arsenic retention calcine (below 5 mg·L −1 ) was far less than the leaching concentration of arsenic in AAR (915 mg·L −1 ).