<p>Electric arc furnace from steelmaking in China generates substantial quantities of Zn-laden dust annually. The accumulation and disposal of electron arc furnace dust cause environmental contamination and resource waste. The phase-change behaviour of the ZnO-Fe₂O₃ system during vacuum carbon thermal reduction remains ambiguous, necessitating a comprehensive investigation. This study investigate the phase-change behaviours of a ZnO-Fe₂O₃ system during vacuum carbon thermal reduction experiments, with varying carbon contents, reaction temperatures, and holding durations. The reduction sequence for iron follows Fe₂O₃(s) → Fe₃O₄(s) → FeO(s) → Fe(s), while for zinc it progresses as ZnO(s) → Zn(s) → Zn(g). Four distinct stages were identified. At temperatures below 1000 °C, reductions of ZnO and Fe₂O₃, are minimal with a slow reaction rate. The medium temperature stage (1000 °C-1050 °C) intensifies reactions, with Zn(g), CO, and CO₂ transitioning to the gas phase, and partial reduction of Fe₂O₃ to Fe, resulting in increased sample weight loss and Zn volatility. In the high-temperature stage (1050 °C-1150 °C), Zn volatility rate peaks at 99.36%, while FeO continues to react with C and CO to yield Fe, leaving residual C. In the final reaction stage ≥ 1150 °C, Zn is almost completely volatilised, and FeO is reduced to Fe. These findings indicate that the vacuum carbon thermal reduction of ZnO-Fe₂O₃ integrates solid–solid and gas–solid reactions, driving Zn volatilisation and Fe enrichment.</p> Graphic Abstract <p></p>