Study of flow modification and inclusion removal in slab tundish due to bottom gas injection.

Abstract

In order to quantify inclusion removal the role of flow pattern inside the tundish is assessed. Also mathematical models of inclusion separation including the influence of inclusion coalescence are discussed. This analysis suggest that as far as small size inclusions are concerned, operational parameters such as piston flow fraction are not important since for them the probability of separation is negligible. However, techniques such as gas curtains are to be considered for better inclusion control. Mathematical and physical modeling results are presented considering association of a porous dam and a ring shaped injection plug positioned around the strand. The results confirm the theoretical expectations as the flow modification, revealed by the mathematical simulation, allows the imprisonment of particles in the reactor and so the fraction of small inclusions leaving the tundish stays under 3% for the gas-assisted strand.