INFLUENCE OF MAIN COMPONENTS ON SOLIDIFICATION BEHAVIORS OF BLAST FURNACE SLAG DROPLET IN VARIABLE COOLING CONDITIONS
Centrifugal granulation is the most feasible technique for heat recovery from molten blast furnace (BF) slag. The granulated slag droplet experiences a complex cooling process to achieve glassy phase for cement clinker. Moreover, the chemical components of BF slag are intrinsic factors of crystallization characteristics. In the present study, an enthalpy-based model is established to explore the solidification behaviors of a melting slag droplet cooled in the complex cooling process. Furthermore, the influence of the main components (corrected optical basicity) is discussed on the temperature distribution and the crystal phase content evolution inside the droplet in the variable cooling process. The results show that the decrease in the corrected optical basicity limits the growth rate of crystal phase, giving rise to the reduction of the crystal phase content of the BF slag droplet. The BF slag with the crystal phase content below 10% is qualified for cement clinker. Accordingly, to meet this demand, the equivalent heat transfer coefficient in the fluidized bed reduces about 60% with the corrected optical basicity declining from 0.681 to 0.656. That means, the BF slag with a low corrected optical basicity value is easier to satisfy the multiple goals of low crystal phase content and high quality heat recovery.