ORIGINAL PAPER Reduction of Tundish Skull and Yield Improvement in Steel Plants Through Physical Modeling of Steelmaking Tundish Systems Dipak Mazumdar • O. P. Singh • Joy Dutta • Shaktimoy Ghosh • D. Satish • S. Chakraborty Received: 28 February 2011 / Accepted: 11 October 2011 / Published online: 8 December 2011 Ó Indian Institute of Metals 2011 Abstract New types of furniture (also termed as flow modifiers or baffles) were incorporated in industrial scale, slab and bloom casting tundish systems with an aim to reduce residual metal loss (i.e., tundish skull) at the end of sequence casting. To this end, water model experiments were carried out in which, slag vortexing phenomena during emptying of tundish was studied embodying different types of furniture into existing tundish designs. These in general indicate that a wedge shaped bottom together with an embedded pouring box applied in conjunction have the potential to reduce tundish skull and improve yield losses significantly. In addition, limited residence time distribution measurement experiments were made to investigate met- allurgical performance of modified design tundish systems. These indicate that deployment of new furniture with minor design modifications, despite contributing to a reduction in tundish capacity (10–12%), do not influence metallurgical performance of steelmaking tundish systems to any signif- icant extent. Accordingly, designs of currently employed slab (32 and 37 tonnes capacity respectively) and bloom casting tundish (10 and a 17 tonnes capacity respectively) systems were modified in four different steel mills and plant trials conducted to assess the extent of yield improvement. Significant improvements in yield losses, to the extent of 50–60%, have been confirmed by the industry during sequence casting. Keywords Steelmaking  Tundish skull  Continuous casting  Physical modeling  Yield improvement 1 Introduction Considerable amount of steel is lost from tundish in the form of solidified skull at the end of sequence casting. This is so, as the presence of an upper slag phase prohibits complete drainage of melt present in a tundish. Thus, towards the end of a casting campaign, as a tundish is being continuously emptied out and the bath level reaches a threshold, a vortex forms above the drainage nozzle and starts entraining the deleterious upper slag phase into the mold. This affects product quality and induces many operational hazards including, buldging and break out. In the caster shop, the operator therefore routinely terminates casting before any significant slag entrainment results into continuous casting mold. As a consequence, some residual steel is left behind in a tundish at the end of sequence casting and this ultimately manifests as a solidified mass that is customarily referred to in the industry as ‘‘tundish skull’’. Significant amount of high quality steel is thus regularly downgraded or lost in every sequence affecting plant productivity adversely. The extent of skull loss gen- erally depends on tundish size, types of tundish furniture, casting rate, tundish nozzle dimension and so on. This is illustrated in Fig. 1 for two different slab casting tundish D. Mazumdar (&) Department of Materials Science and Engineering, Indian Institute of Technology, Kanpur 208016, India e-mail: dipak@iitk.ac.in O. P. Singh Hospet Steel, Hospet, Karnataka, India J. Dutta  S. Ghosh JSPL, Raigarh, India D. Satish JSW, Torangallu, Karnataka, India S. Chakraborty RINL, Vishakhapattnam, India 123 Trans Indian Inst Met (December 2011) 64(6):593–605 DOI 10.1007/s12666-011-0067-8