Oxygen-assisted zinc recovery from electric arc furnace dust using magnesium chloride

Electric arc furnace (EAF) dust is an important secondary resource containing metals like zinc (Zn) and iron (Fe). Recovering Zn from EAF dust can contribute to resource recycling and reduces environmental impacts. However, the high chemical stability of ZnFe2O4 in EAF dust poses challenges to Zn recovery. To address this, a facile approach of oxygen-assisted chlorination using molten MgCl2 is proposed. This work focuses on elucidating the role of O2 in the reaction between ZnFe2O4 and molten MgCl2. The results demonstrate that MgCl2 effectively breaks down the structure of ZnFe2O4 and a high O2 atmosphere significantly enhances the separation of Zn as ZnCl2 from other components. The presence of O2 facilitates the formation of MgFe2O4, which stabilizes Fe and prevents its chlorination. Furthermore, the study reveals that excessive use of MgCl2 results in increased evaporation losses, while higher temperatures promote the rapid separation of Zn. Building on these findings, the successful extraction of ZnCl2-enriched volatiles from practical EAF dust through oxygen-assisted chlorination is demonstrated. Under optimized conditions, this method achieves an exceptional Zn chlorination percentage of over 97mass% within a short period, while Fe chlorination remains below 1mass%. The resulting volatiles contain 85mass% of ZnCl2, which can be further processed to produce metallic Zn. These findings provide valuable guidance for the selective recovery of valuable metals, particularly from solid wastes like EAF dust.