A New EAF Dust Treatment Using a Nitric Acid Solution

摘要

Electric Arc Furnace (EAF) dust, defined as special industrial waste in Japan, is treated through pyrometallurgical processes in which crude ZnO powder is recovered. However, a new on-site type process is desired to reduce treatment cost and cost of transportation of the dust. Although many EAF dust treatment processes have been proposed, most of them are not good for on-site treatment because they need a large scale operation. A hydrometallurgical process is considered to be suitable for such an on-site treatment. Many hydrometallurgical processes have been proposed but no commercial applications are currently employed in Japan. A new hydrometallurgical process for EAF dust is proposed in this study. Nitric acid solution is used for the extraction of ZnO from the dust. Some characteristics of the process are as follows: (1) Recovery of Zn from zinc ferrite in EAF dust is the target, while the dissolution of Fe is limited by controlling the pH of the solution. (2) Zn is recovered as metallic Zn by electrowinning from the solution and nitric acid is regenerated in the anode.