Abstract:The crystallization of molten blast furnace (BF) slag can increase its viscosity and reduce its liquidity, which can affect the quality of slag fibers during BF slag direct fibrosis process. The chemical composition is one of the main factor which impacts on the crystallization behavior of molten BF slag. FactSage thermodynamics simulation, X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), energy dispersive spectroscopy (EDS) and hot thermocouple technique (HTT) were performed to investigate the effect of Al2O3 mass fraction (11%-19%)on the crystallization behavior of BF slag during cooling process. It was found that the main crystallized minerals of BF slag were melilite, anorthite, clinopyroxene and wollastonite during the cooling process. The critical cooling rates of BF slag with Al2O3 mass fraction of 11%, 13%, 15% and 17% were 60, 50, 15, 15 ℃/min, respectively. The crystallization of molten BF slag was not observed when Al2O3 mass fraction was increased to 19% and the cooling rate was higher than 3 ℃/min. Increase of Al2O3 content decreased the initial crystallization temperature and the critical cooling rate of BF slag, which would benefit the production of slag fiber using BF slag. This work aims at investigating the influence of Al2O3 content on the crystallization behavior of molten BF slag, which would lay a theoretical and experimental foundation for the direct production of slag fiber using molten BF slag.
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