Insights into Non-free Opening of Ladles: Filler Sand Chemistry Modifications for High Mn Steel Billet Casting

Ladle well filler sand plays a significant role in ensuring the free opening of ladles at the caster. Free opening is essential for preventing productivity losses due to abrupt interruptions during casting. Plant data analysis, thermodynamic and experimental assessments were carried out to identify the main causes of non-free opening. Plant data analysis revealed that the casting of high Mn (> 0.8%) steel grades (increase by ~ 42% (2019–2022)) has a direct impact on non-free opening (increase by ~ 1.1%). The reason was found to be the formation of MnO during the reaction between liquid steel and filler sand, which increased the rate of sintering. Based on further investigations, it was recommended to modify the chemistry of filler sand by optimizing its SiO₂ and Fe₂O₃ content for casting of high Mn grade steels. Plant trials with the recommended filler sand showed improvement in free opening performance which increased from 98.5% to ~ 99.1%.