Abstract
• The crystallization ability of blast furnace slag is weakened with an increase in BaO content. • One-dimension growth of crystals at low temperature is identified. • A high BaO content induces a phase transformation from melilite to merwinite. Investigating the crystallization behavior of BaO-bearing blast furnace slag (BFs) is of great significance for the dry granulation technology to guide the production of glassy slag with high hydration activity, and simultaneously collect the waste heat of hot slag. In this study, the influence of BaO content on the crystallization behavior was investigated through in-situ observation using a confocal laser scanning microscope (CLSM). The theoretical calculations by FactSage 8.0 and X-ray diffraction (XRD) analysis of the quenched slag were carried out for the crystalline phases characterization. The results showed that the incubation time increased in the isothermal crystallization process and the initial crystallization temperature decreased in the continuous cooling process with the increasing BaO concentration, indicating that the crystallization ability of the slag was weakened. BaO existence had little effect on the crystal morphology during the isothermal crystallization process at 1200℃. Furthermore, the crystallization kinetics analysis of the JMA model showed the Avrami index n close to 1.5, indicating the one-dimension growth of crystals at low temperature. The akermanite (Ca 2 MgSi 2 O 7 ) and gehlenite (Ca 2 AlSi 2 O 7 ) were the main crystalline phases, and their precipitation was restrained to a certain extent as the BaO content increased.
Published Version
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