A combined hydro-pyrometallurgical process for zinc oxide and iron oxide extraction from electric arc furnace dust waste

Abstract

Electric arc furnace (EAF) dust waste is generated during EAF steelmaking process. Zinc and iron which comprise the highest composition in EAF dust are secondary resources for making steel products. They mainly present in the form of stable zinc ferrite (ZnFe2O4), leading to the extraction process difficult. In this study, a combined hydro-pyrometallurgical process was developed to extract both zinc oxide and iron oxide from EAF dust. Initially, hydrometallurgical leaching was used to leach zinc and iron from EAF dust. Results show that 10 M of hydrochloric acid (HCl) at 25°C can achieve zinc and iron leaching of 92% and 91%, respectively. The liquid solution post leaching was subjected to pyrometallurgical process to form Fe2O3 mixture at 250°C while retaining zinc chloride (ZnCl2) as solid residue. Then, the obtained ZnCl2 was treated with sodium hydroxide (NaOH) and nitric acid (HNO3) to form ZnO. The Fe2O3 and ZnO extraction were 2.5 g and 1.5 g, respectively out of 10 g of EAF dust with their respective purity of 87% and 98%. The developed process can provide new insight into recovering zinc oxide and iron oxide simultaneously from EAF dust, thereby paving the way to circular economy development and sustainable steel dust waste management for steel industries.