Progressive low-temperature volatilization control: Efficient separation of arsenic and antimony from smelter dust.

ABSTRACT

Given the high toxicity of arsenic (As) and the strategic importance of antimony (Sb), the separation of As and Sb has become a pivotal concern in the disposal of arsenic­antimony flue dust and other arsenic­antimony hazardous wastes. In this study, we propose a controlled roasting process employing anthracite and sulfuric acid additives to efficiently separate As and Sb at relatively low temperatures. Thermodynamic calculations revealed that the interactive reactions between arsenic and antimony oxides in conventional pyrometallurgical processes were the primary hindrance to their effective separation. However, the synergistic effect of anthracite and sulfuric acid not only disrupted the interactive reactions but also promoted the high-efficiency volatilization of As at low temperatures, thereby creating favorable conditions for the separation of As and Sb. Furthermore, a series of comparative experiments and comprehensive analyses regarding the evolution of phase composition, valence state, and morphology were conducted, revealing the underlying mechanisms of the effects of temperature and carbon addition. Through optimization, 91.24 % of As was successfully volatilized, while the volatilization efficiency of Sb was significantly reduced to 9.43 % under optimal conditions, involving a roasting temperature of 400 °C, anthracite addition of 1.6 %, sulfuric acid dosage of 0.135 mL/g, and a roasting duration of 3 h.