During production of steel in electric arc furnaces, dust formation occurs, whereby about 15-25 kg of dust accumulate by production of 1 t of steel. The process of steel production basically includes the five steps of furnace charging, melting, refining, slag foaming and casting. During those steps, that partly involve addition of coal powder and introduction of CO gas streams, a gaseous phase is being extracted at the top of the furnace. This gas stream is combusted, cooled and cleaned from dust. The dust containing high amounts of zinc, lead and cadmium is caught in bag filters and due to its hazardous properties it has to be stored in special landfills (Guézennec et al. 2005). Generally, the dust contains mainly metal oxides (especially iron oxides), silicates, sulphates and coke whereas the composition and mineralogy of those phases can be very complex (Hagni et al. 1991; Sofilic et al. 2005).