Reduction of electric arc furnace dust with solid iron powder

Electric arc Furnace (EAF) dust contains, on average, about 19 mass% zinc and 3 mass% lead. Due to the presence of this lead, as well as small amounts of cadmium and hexavalent chromium, EAF dust has been classified as a hazardous waste by various government regulatory agencies. Currently, most dust treatment processes employ carbon as a reducing agent for the zinc oxide in the EAF dust. The zinc vapour that is produced can be condensed. In the present work, the reaction of EAF dust with iron was studied in an argon atmosphere using a thermogravimetric technique. First, a thermodynamic study was performed using the F*A*C*T computational system. Then, the effects of briquetting pressure, argon flowrate, briquette aspect ratio (1/d), iron particle size, amount of iron added, as well as additions such as lime, sodium chloride and zirconium oxide on the kinetics of the reduction reaction were investigated. It was found that, initially, the reaction was chemically controlled with an activation energy of 159 kJ/mol. Then, after a product layer 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.