Keywords: characterisation, electric arc furnaces, flue dust, EAF dust, leaching tests, photobacterium phosphoreum, Spain, toxicity tests, environmental pollution, steel making, leachate, ecotoxicity, heavy metals, zinc oxide, lead oxide, iron oxide, chrome, nickel, manganese
Electric arc furnace flue dust: characterisation and toxicity with Photobacterium phosphoreum
During steelmaking in electric arc furnaces (EAFs), 10 to 15 kg of dust, consisting of a mixture of zinc, lead and iron oxides and to a lesser degree chrome, nickel and manganese, is generated per ton of steel product. In many countries, the disposal of EAF dust in landfill sites is regarded as an environmental hazard, since toxic metals may be leached into drinking water supplies. This work gives the results of a study of the physical, chemical, mineralogical and toxicological properties of dust produced in Spanish EAFs. EC50 concentrations (Microtox Assay) are determined by studying the incubation time of the bacteria and an exponential ratio is then established between EC50 values and the heavy metal content of the leachates which are obtained (US EPA protocol). The relationship between the pH at which the metals are extracted and their ecotoxicity is also studied. Average EC50 values of 1 250 mg 1-1 are found when the heavy metals are extracted at a pH of 4-4.5.