Characteristics of the process of electric arc furnace dust roasting with calcium and magnesium oxides

Electric arc furnace dust (EAFD) has a significant content of zinc exceeding considerably its content in ore materials. The main phase of zinc in the dust is hardly soluble ferrite ZnFe2O4. In this work, the process of EAFD roasting with calcium and magnesium oxides was investigated to transform ferrite to highly soluble oxide form and to remove halogens and lead. The elemental and phase composition of the dust of two Russian plants were studied. Thermodynamic calculations and laboratory experiments were carried out in ZnFe2O4-CaO and ZnFe2O4-MgO systems using pure components at 900-1000°C. Thermodynamic modelling were also carried out for EAFD in the presence of calcium and magnesium oxides. It has been found out that in the two different samples of dust from different plants quantities of valuable components varies considerably, but the mineralogical composition is similar. Zinc is detected in the dust samples not only in ferritic form; some of the zinc is also present in the form of ZnO...