Deflocculation and Classification of Electric Arc Furnace Dust in Aqueous Solution

Electric arc furnace (EAF) flue dust is generated during EAF steelmaking from iron-containing scrap such as recycled automobile bodies. The relatively high level of Zn (20-30wt%) in EAF dusts provides a potentially valuable resource, even though the zinc is present as oxide phases such as zincite (ZnO) and zinc ferrite (ZnFe2O4). In this work, a method to deflocculate and disperse ZnO and ZnFe2O4 particles in aqueous suspension of EAF dust is developed and the efficiency of Zn recovery by the classification method was evaluated. Major findings of this study indicate that citric acid, a tetradendate chelating agent, demonstrates the best liberation and dispersion efficiency for EAF dust. Elutriating at 0.01 cm/min fluid velocity we recover 10wt% of EAF dust (mostly ZnO particles) at a grad of 70 wt% Zn from a well-liberated and dispersed suspension of EAF dust. About 30 wt% of Zn recovery may be achieved using only simple classification.