Leaching and cementation of heavy metals from electric arc furnace dust in alkaline medium

Laboratory-scale research has focused on the treatment of EAF steel making dusts by an alkaline caustic leach process, combining both hydro- and environmentally suitable metallurgical methods to recover zinc and lead. Optimum conditions were found to be: 95 °C, 1/7 solid/liquid ratio, 10 M NaOH and 2 h leaching time. Under these conditions, 85% Zn and 90% Pb were recovered. The leachate was further purified by zinc cementation at 50 °C to remove the metallic impurities (Pb, Cu, Cd, etc.) and to make it suitable for alkaline zinc electrolysis. The cementation process was chemically controlled with an activation energy of 26.7 kJ mol− 1.