Improved hydrometallurgical extraction of zinc and iron from electric arc furnace (EAF) dust waste using hydrochloric acid

Abstract

In electric arc furnace (EAF) steelmaking process, a high amount of flue dust called EAF dust is generated. To date, approximately 7.5 million tons of EAF dusts are generated annually around the world. EAF dust has been classified as hazardous by-product due to its heavy metal compositions such as iron, zinc, manganese, nickel and lead. Disposal of EAF dust by landfilling causes environmental pollution problems. Zinc and iron which constitute the greatest compositions of EAF dust (~ 8 to 40 wt% & ~ 16 to 60 wt%, respectively) are commercially valuable. They can be extracted and recycled to steel industry. Nevertheless, zinc and iron primarily exist in zinc ferrite (ZnFe2O4) form. The formation of ZnFe2O4 has impeded zinc and iron extractions. Thus, an improved hydrometallurgical process for the extraction of zinc and iron from EAF dust was investigated in current project. The leaching agent used was hydrochloric acid (HCl). Parameters investigated were acid concentration, leaching temperature and leaching time. Results showed that zinc and iron extractions have been improved as compared to previous work. The highest zinc and iron extractions were 94% and 93%, respectively using 10M HCl at 25 °C with solid-to-liquid (S/L) ratio of 1:3 after 15 minutes of leaching. This project demonstrates that zinc and iron are feasible to be extracted from EAF dust via hydrometallurgical process using HCl as leaching agent.