Modelling of the Steel/Slag Interface in a Continuous Casting Tundish

It is very important to understand the underlying physical phenomena at the steel/slag interface in a continuous casting tundish in order to control reoxidation and deoxidation phenomena that can occur. Aiming to investigate probable sources of exogenous inclusions originating from the covering slag, an existing mathematical model of the tundish was augmented to include key physical parameters needed for the prediction of the physical behaviour of steel/slag mixing phenomena. Results showed a recirculation flow in the inlet region to be responsible for both the entrainment of steel drops into the slag and slag fragments into the steel. The highest concentration of slag in the steel was found to be in the area behind the inlet where slag fragment sizes are smaller due to a high degree of turbulent energy dissipation. Likewise, higher concentrations of steel in the slag, consisting of smaller steel droplets, were only found in the inlet region and along the walls. The results indicate that only small slag fragments of approximately 10-50 microns from the covering slag reach the outlet.