Phase and Morphology Transformations in Sulfur-Fixing and Reduction Roasting of Antimony Sulfide

Metallurgical extraction of antimony (Sb) currently has the limitations of high energy consumption and adverse environmental impact. In this study, we proposed a cleaning process to extract Sb by metallurgy and beneficiation based on S-fixing and reduction roasting of Sb2S3. Metallic Sb can be obtained directly by using zinc oxide (ZnO) and carbon as sulfur-fixing and reducing agents, respectively, at 600–1000 °C, wherein S is fixed in the form of ZnS. The thermodynamic feasibility of the roasting process and the effects of a range of process parameters on Sb generation were investigated comprehensively. The optimum conditions for metallic Sb generation were determined to be as follows: temperature of 800 °C, C powder size of 100–150 mesh, ZnO content of 1.1 times its stoichiometric requirement, and a reaction time of 2 h. Under these conditions, the proportion of Sb distributed in the metal phase reached 90.44%, and the S-fixing rate reached 94.86%. The phase transformation of Sb progressed as follows: Sb2S3 → Sb2O3 → Sb. The Sb particles exhibited mainly spherical and hexahedral morphologies after quenching and furnace cooling, showing minimal bonding with ZnS. This research is potentially beneficial for the further design process of Sb powder and ZnS recovery by mineral separation.