Effect of slag cover on heat loss and liquid steel flow in ladles before and during teeming to a continuous casting tundish

Mathematical modeling of transient fluid flow and heat transfer of melt in the ladle has been carried out, both before and during teeming of the melt to a tundish. The model involves solution of the transient, two-dimensional form of the turbulent Navier-Stokes' equation along with the equations of turbulence energy, energy dissipation rate of turbulence energy, and thermal energy conservation in the cylindrical coordinate system. Two different heat loss conditions have been assumed to occur from the top free surface of the melt in the ladle. When the ladle has an insulating layer of slag, temperature stratification occurs within the melt with the coolest melt in contact with the ladle bottom. The degree of temperature stratification increases with the increase in holding time. Pouring of the melt from such a ladle to the tundish, however, results in near uniform ladle stream temperature during the 47 minutes of pouring period considered in the present study. This is especially true if the melt in the ladle is held for a period of 20 minutes prior to teeming. When the melt in the ladle loses an appreciable amount of heat from the top due to a thin layer of slag, the average temperature of the melt drops considerably during the holding period although there is no temperature stratification. Pouring from such a ladle results in a continuous decline of the ladle stream temperature, even though the pouring starts after a holding period of 5 minutes. Formerly Graduate Student, Department of Materials Science and Engineering, Ohio State University