REDUCTION OF ELECTRIC-ARC FURNACE DUST WITH SOLID IRON-POWDER

Electric arc Furnace (EAF) dust contains, on average, about 19 mass% z inc and 3 mass% lead. Due to the presence of this lead, as well as sma ll amounts of cadmium and hexavalent chromium, EAF dust has been class ified as a hazardous waste by various government regulatory agencies. Currently, most dust treatment processes employ carbon as a reducing a gent for the zinc oxide in the EAF dust. The zinc vapour that is produ ced can be condensed. In the present work, the reaction of EAF dust wi th iron was studied in an argon atmosphere using a thermogravimetric t echnique. First, a thermodynamic study was performed using the FA*C*T computational system. Then, the effects of briquetting pressure, argo n flowrate, briquette aspect ratio (1/d), iron particle size, amount o f iron added, as well as additions such as lime, sodium chloride and z irconium oxide on the kinetics of the reduction reaction were investig ated. It was found that, initially, the reaction was chemically contro lled with an activation energy of 159 kJ/mol. Then, after a product la yer had formed on the outer surface of the briquette, the reaction was controlled by the transport of the zinc vapour away from the reaction interface.