A novel hydrothermal method for zinc extraction and separation from zinc ferrite and electric arc furnace dust

Abstract

A novel hydrothermal process was developed to extract zinc from pure zinc ferrite (ZnFe2O4) nanopowder and zinc-containing electric arc furnace (EAF) dust using hexahydrated ferric chloride (FeCl3·6H2O) as a decomposing agent. The effects of solid FeCl3·6H2O to ZnFe2O4 ratio by mass (RF/Z), hydrothermal reaction temperature, and time on zinc extraction were systematically investigated. In the results, when the hydrothermal reaction is conducted at 150°C for 2 h with RF/Z of 15:20, the efficiency of zinc extraction from ZnFe2O4 reaches 97.2%, and the concentration of ferric ions (Fe3+) in the leaching solution is nearly zero, indicating a high selectivity for zinc. In addition, the zinc extraction efficiency from the EAF dust reaches 94.5% in the case of the hydrothermal reaction performed at 200°C for 10 h with the solid FeCl3·6H2O to EAF dust ratio by mass (RF/EAF dust) of 15:10. Zinc and iron separation is achieved by adjusting the pH value of the leaching solution according to the different precipitation pH values of metal hydroxides.