POSSIBILITIES OF PROCESSING DIOXIN CONTAI NING FLUE DUSTS FROM SECONDARY ALUMINUM SMELTERS

Remelting of contaminated oxidised aluminium scrap in rotary furnaces under a salt slag leads to a flue dust which consists of sublimed alka line metal chlorides and fluorides, lime (which is added to the flue g as for adsorption purposes) and alumina. Beside minor amounts of heavy metals it contains free and organic carbon (e.g. in form of PCDD and PCDF) and metallic aluminium. A combined process is proposed in which the toxic organic compounds are destroyed by a pyrometallurgical treat ment either at low or high temperatures. The valuable substances are r eclamated in form of industrial salt by hydrometallurgical process met hods.