Generally, reactions and forming phases during ironmaking can be thermodynamically predicted using equilibrium phase diagram. However, at low temperature it will likely to be different from predicted phases and deviate from equilibrium. Hence, knowledge of solid state reaction at low temperature is required to control the melting behavior of slag phase in blast furnace. Formation of 2CaO·SiO2 by the reaction between gangue SiO2 and liquid CaO-FeO phase will give negative effect to molten slag formation during ironmaking process, and enhancing the dissolution of SiO2 into CaO-FeO liquid phase is crucial. It was found that 2CaO·SiO2 phase layer formed at the interface between SiO2 and CaO-FeO melt by rapidly heating the sample to 1 423 K. Dissolution of SiO2 into CaO-FeO melt was enhanced by Al2O3 addition to the CaO-FeO melt. When the sample was rapidly heated to 1 473 K, formation of 2CaO·SiO2 was not observed and the dissolution of SiO2 into CaO-FeO liquid phase was significant. Rapid heating to 1 473 K will avoid formation of 2CaO·SiO2 phase and enhance melting of gangue minerals to form liquid slag.
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|Published - 2020