Solidification behaviors of a molten blast furnace slag droplet cooled by air

Aiming at the heat recovery of BF slag by dry granulation technology, a heat transfer model based on the enthalpy method is promoted to analyze the solidification behaviors of a molten BF slag droplet cooled by air. In this model, a temperature range instead of a constant temperature for solidification and variable physical properties during the cooling process are taken into consideration. Furthermore, both convective and radiative heat transfer are employed as the boundary conditions. With the finite difference method, the temperature distribution, movement of phase change interfaces, cooling rate and solidification time are obtained for the air cooling of a molten BF slag droplet. The effects of phase change temperature range, variable thermal conductivity, droplet diameter, air velocity and initial air temperature are discussed on the solidification process. The results suggest that solidification occurred in a temperature range as well as the variable thermal conductivity have an opposite effect on the heat transfer and solidification process. The decrease of the slag droplet diameter and increase in the air velocity fasten the cooling rate and shorten the solidification time.