In this study, an electric-arc furnace dust (EAFD) sample resulted from a pyrometallurgical ferrochrome production process was examined in detail by X-ray photoelectron spectroscopy (XPS) analysis. According to the X-ray fluorescence (XRF) results, the EAFD sample mainly consists of 40.17% MgO, 33.86% SiO2 and 19.22% Al2O3. As expected, the sample also contains 3.21% Cr2O3 and 2.89% Fe2O3 contents. The wet-sieving analysis shows that 80 and 50% cumulative passing sizes by weight were determined as approximately 143 and 79 µm, respectively. From the XPS results obtained, the EAFD sample elementally consists of 49.95% O, 17.12% Mg and 7.24% Si which are in line with the XRF results. In addition, the sample also has potentially hazardous two heavy metals, 0.99% Cr and 2.60% Zn. Specifically, the detailed XPS analysis indicates that chromium exists as two forms, hexavalent chromate (VI) and trivalent chromite (III). By comparing the Cr peaks observed, the XPS analysis also shows that the relative amount of hexavalent form is higher than immobile trivalent chromite. Considering its fine size together with the high amount of hazardous hexavalent chromate content, it can be surely said that highly mobile and toxic Cr (VI) content of the EAFD sample must be immobilized as much as possible prior to disposed in landfills.
Anahtar Kelimeler: Electric-arc furnace dust, XPS analysis, hexavalent chromate, hazardous pollutants
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