Thermodynamic and Kinetic Investigations of Leaching Calcined By-products of EAF Dust Waelz Process in Sodium Hydroxide Solutions

Electric-arc furnace dust (EAFD), containing Zn more than 20%, is prospective raw-material for zinc, lead, and other valuable components recovery. Pyrometallurgical EAF dust treatment has low selectivity, poor quality final products, high consumption of carbon reducing agent, and environmental hazards. The presence of high ferrite and impurities, especially halides, don’t allow wide applications of hydrometallurgical methods. To increase zinc extraction at the stage of leaching, it is necessary to develop processes of EAF dust pretreatment for the purpose of ferrite destruction and halides removal. The most rational variant is the two-stage EAF dust Waelz process, with chlorides vaporization and production of zinc-containing calcined by-products. Alkaline leaching of such material allows to selectively recover zinc into concentrated solutions. It allows to produce high-quality zinc powders. This process requires minimum capital and operating costs, and has minimum influence on the environment.