Physical and mathematical modelling to study the effect of ladle shroud mis-alignment on liquid metal quality in a tundish

Abstract

The present work involves the use of physical and mathematical modelling in order to study the effect of slight mis-alignments of the ladle shroud on liquid steel quality output from a delta shaped, four strand, continuous casting tundish. For the physical modelling, a full scale water model was used to observe the effects of ladle shroud alignment on steel quality in terms of "slag" entrainment into the individual moulds. The ladle shroud was purposefully biased by about 4 to 5 degrees off-vertical, and the number of "slag particles" entering individual strands of the 4 strand billet caster were measured during a ladle change, and compared with the "no bias" condition. A one third scale water model was also used to perform tracer dispersion experiments and to help visualize the effects of the biased shroud. Finally, a 3D mathematical model was developed and contours of velocity and/or turbulence were examined under a "biased shroud" condition. In the mathematical model, the shroud was biased in all directions. The mathematical predictions were in good agreement with physical modelling results. Given the great sensitivity of liquid metal quality to this slight misalignment during a ladle change, with the tundish "furniture" used, possible remedial measures are discussed for equivalent steel plant operations. © 2011 ISIJ.