Cooling and phase evolution of a molten blast furnace slag particle

Abstract

In the dry centrifugal granulation process to treat liquid blast furnace slag, it is critical to clarify the cooling and crystallization characteristics of slag particles, which greatly determine their subsequent reutilization and waste heat recovery. Here, we investigated the cooling characteristics of a single slag particle by simulation in terms of crystal phase content variation, temperature and velocity distributions, average cooling rate, etc. The most influential operating parameter was demonstrated to be the particle size and the dimensionless average cooling rate was determined, thereby helping regulate the cooling process more effectively. Moreover, the exploration in the slag composition indicated that reducing the corrected optical basicity was extremely beneficial to promote the particle quality. In the selection of thermophysical parameters, we concluded that constant viscosity was feasible, while density, conductivity and heat capacity should keep temperature-dependent. These results are expected to provide guidance for the application of dry centrifugal granulation technology.