Integrated hydrometallurgical process for production of zinc from electricarc furnace dust in alkaline medium

In this study, a novel and integrated hydrometallurgical process for the pr oduction of zinc powder from electric are furnace (EAF) dust in alkaline me dium is reported. The dust is firstly hydrolysed in water, and then fused i n caustic soda at 350 degreesC for Ih, followed by leaching in alkaline sol ution in which both zinc and lead are effectively extracted. Zinc powder is then produced by electrowinning from the leach solution after the lead is selectively removed by precipitation using sodium sulphide as precipitant. The EAF dust tested contained 25% Zn, 1.8% Pb and 33% Fe. It was found that 38% of zinc and 68% of lead could be extracted from the dust when leached directly in caustic soda solution. Leaching of zinc increased to 80% when d ust was directly fused with caustic soda followed by alkaline leaching. How ever, the leaching further increased to 95% when the dust was hydrolysed fi rst with water before fusion. Zinc powder with a purity of 99.95% was then produced by electrowinning from the lead depleted solution. Stainless elect rodes were used as both anode and cathode. (C) 2000 Elsevier Science B.V. A ll rights reserved.