Effect of B₂O₃ addition on mineralogical phases and leaching behavior of synthetic CaO–SiO₂–MgO–Al₂O₃–CrOₓ slag
Lin, Yong; Luo, Qingyun; Yan, Baijun; Fabritius, Timo; Shu, Qifeng (2020-03-18)
Lin, Y., Luo, Q., Yan, B. et al. Effect of B₂O₃ addition on mineralogical phases and leaching behavior of synthetic CaO–SiO₂–MgO–Al₂O₃–CrOₓ slag. J Mater Cycles Waste Manag 22, 1208–1217 (2020). https://doi.org/10.1007/s10163-020-01015-4
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https://urn.fi/URN:NBN:fi-fe2020091069232
Tiivistelmä
Abstract
Boron oxide is frequently applied in modification of stainless steelmaking slag to mitigate the disintegration of slag. In this work, the effect of B₂O₃ on mineralogical phases and hexavalent chromium leaching behavior of synthetic CaO–SiO₂–MgO–Al₂O₃–CrOx slag was investigated. Di-calcium silicate, merwinite, spinel, akermanite, and matrix phase were observed as main minerals in slags by scanning electron microscope (SEM) equipped with energy-dispersive spectrometry (EDS) and X-ray diffraction (XRD) techniques. It was found that 2% B₂O₃ addition is sufficient to eliminate the disintegration of synthetic slag by suppressing the phase transition to γ-Ca₂SiO₄. The size of spinel phase increases with increasing B₂O₃, which could be well interpreted by enhanced Ostwald ripening. The amount of Ca₂SiO4 phase in slag was reduced by addition of B₂O₃; however, excess B₂O₃ (> 2%) addition would significantly increase chromium concentration and overall chromium distribution in Ca₂SiO₄ phase. Leaching results according to US-EPA-3060A method indicated that excess boron oxide addition (> 2%) leads to a significant increase of hexavalent chromium leaching concentrations and should be avoided for stabilizing stainless steel slag.
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