Selective Separation Mechanism of Arsenic and Antimony in Lead-Zinc Smelting Dust

Abstract

The smelting process of lead (Pb) and zinc (Zn) affords various types of dusts, which often contain high concentrations of arsenic (As) and antimony (Sb) introduced into the system from raw materials. These dusts also contain economically valuable elements such as bismuth, tin and tellurium. Herein, we explored an efficient As removal method to facilitate the comprehensive recovery of valuable metals from dusts produced during Pb and Zn smelting. As- and Sb-bearing dust produced during the Pb-Zn smelting process was subjected to alkaline oxidative pressure leaching. The total leaching efficiency of As (measured from both the leaching and washing solutions) increased to 98.26%, whereas that of Sb was < 0.5%. During the reaction, trivalent As was oxidised to pentavalent As, which transformed into sodium arsenate (Na₃AsO₄·10H₂O). As the solubility of Na₃AsO₄·10H₂O reduces in highly alkaline solutions, this led to its precipitation and a corresponding reduction in the leaching efficiency of As. However, after washing, the alkalinity of the solution changed, facilitating the dissolution of Na₃AsO₄·10H₂O. In addition, under high alkalinity, Sb converts to sodium antimonate. Furthermore, at low alkalinity, the solubility behaviours of Na₃AsO₄·10H₂O and sodium antimonate are inversely related, facilitating their effective separation.