Reduction behavior and multiphase reaction mechanism of antimony oxide using representative biomass

The traditional reduction smelting process for antimony oxide relies on coal-based reductants, which not only cause severe environmental pollution but also exhibit low reduction efficiency. This study systematically investigates the use of biomass as a reducing agent for antimony oxide reduction and elucidates its underlying reaction mechanism. In this study, five representative biomass types were first characterized, and their pyrolysis behavior was evaluated. Subsequently, the effects of biomass, biochar, and biomass pyrolysis gas on the reduction of antimony oxide were examined separately. Finally, the mechanism of antimony oxide reduction by biomass was revealed. The results indicate that pine sawdust exhibits the best reduction performance due to its high volatile content (71.47%), low ash content (0.96%), and well-developed porous structure. Additionally, at 1073 K with a reaction time of approximately 15 min, a high direct yield of antimony can be achieved. The synergistic interaction between gaseous reducing agents from biomass pyrolysis and biochar establishes a gas-liquid-solid three-phase reaction system, significantly enhancing the reduction process. This study clarifies the multiphase synergistic mechanism of antimony oxide reduction by biomass, providing theoretical insights to support the advancement of green and low-carbon metallurgical technologies.