Research on the separation of antimony-bismuth alloy by circulating gasification-directional condensation

Antimony and bismuth are critical minerals, which their alloys hold significant strategic value in semiconductors, aerospace, and electromagnetic materials. However, conventional hydrometallurgical recycling routes suffer from long processing times and severe environmental pollution. Here, we propose a circulating gasification-directional condensation method as a green alternative for Sb-Bi separation. Thermodynamic analysis reveals that the vapor pressure ratio of Sb to Bi decreases with increasing temperature, and a condensation temperature difference of approximately 200 K between the two elements provides the thermodynamic basis for directional condensation. Using a multistage condensation-reflux setup at 5 Pa and 1223 K for 4 hours, we obtain crude Sb and Bi with purities of 99.75 wt% and 95.81 wt%, and direct recovery rates of 99.45% and 74.13%, respectively. Cluster simulation results show that the diffusion coefficient of Sb atoms is higher than that of Bi atoms, and Sb-Bi preferentially form stable heterogeneous clusters, leading to the overlap of condensation temperature ranges. This study offers both mechanistic insights and practical guidance for the sustainable recovery of critical metals.