Application Of Tundish Nozzle In Continuous Casting Process
2021 08/27
The formation of accretions or clogging of Tundish Nozzles in the continuous casting of steel is detrimental both to caster productivity and to eventual inclusion content of the final product. The cause of the clogging is related to a combination of operating criteria including ladle slag practice, tundish refractory, deoxidation methodology and temperature. To assess the effect of various slag components on clogging a mineralogical and rheological study was conducted on both plant and simulated accretion material. Minerals belonging to the lime-alumina-silica system such as hibonite, gehlenite, mullite, spinel and corundum, all having solidification temperatures at or above steelmaking temperatures, were most prevalent. In Mn-rich melts larnite, hibonite and a glassy phase were predominant. The rheological studies confirmed the formation of a significant solids fraction near steelmaking temperatures for basic melts whereas high (>30w/o) Mn melts were glassy. As well, the plate composition of the gating system was also deemed to contribute to the problem, with ZrO2 being preferable to Al2O3. Results are discussed with a view to designing tundish slags to minimise formation of refractory solids while maintaining reasonable compatibility with refractory and gating system practice.
