CHARACTERIZATION OF STEEL MILL ELECTRIC-ARC FURNACE DUST

摘要

EAF dust is a complex material consisting mostly of metal oxides. Since electric arc furnaces typically rely on scrap metal for their charge and the composition of the dust is directly associated with the chemistry of the metallic charge used, increased use of galvanized steel to manufacture automobile bodies and paneling has increased the zinc content in the dust over the years. When galvanized steel scrap is melted in a steel making furnace, most of the zinc vaporizes and ends up in the dust as zinc oxide and zinc ferrite. In addition, trace quantities of precious metals such as gold are also found in EAFD.In order to make a complete characterization of electric-arc furnace (EAF) dust, as hazardous industrial waste, and to solve its permanent disposal and/or recovery, bearing in mind both the volumes formed in the steel industry and experiences of developed industrial countries, a study of its properties was undertaken. For this purpose, samples of EAF dust, taken from the regular production process in more Integrated iron and steel works were subjected to a series of tests. The chemical composition of EAF dust samples was investigated by means of a several different analytical methods. The results from the chemical analysis show that the approximate order of abundance of major elements in EAF dusts is as follows: Fe, Zn, Mn, Ca, Mg, Si, Pb, S, Cr, Cu, Al, C, Ni, Cd, As and Hg. Granular-metric composition of single samples was determined by applying sieve separation. Scanning electron micro-structural examination of EAF dust microstructure was performed and results indicated that all twelve EAF dusts were composed of solid spherical agglomerates with Fe, Zn, Pb, O, Si and Ca as the principal element. The investigation of grain morphology and the mineralogical composition of EAF dust were taken by combination of high resolution Auger electron spectroscopy (HR AES), X-ray photoelectron spectroscopy (XPS) and X-ray powder diffraction analysis. The analysis of XPS-spectra determined the presence of zinc in the form of ZnO phase and the presence of lead in the form of PbO phase, i.e. PbSO_3/PbSO_4 forms. The results of the X-ray diffraction phase analysis show that the basis of the examined EAF dust samples is made of a mixture of metal oxides, silicates and sulphates.