Evaluating Plasma Torches as a Low‐Decarburization Preheating Method for MgO–C Refractory Linings

Magnesia–carbon refractories are widely used as ladle lining materials in steelmaking due to their excellent thermal and chemical stability. Carbon retention is critical for extending refractory lifespan, as carbon loss significantly accelerates wear. Preheating‐induced decarburization typically occurs in oxygen‐rich atmospheres and in the presence of combustion byproducts from hydrocarbon fuels. This study investigates plasma heating as an alternative preheating method to mitigate initial decarburization. Full‐scale industrial trials are conducted using 0.7 and 1.5 MW plasma torches with nitrogen as primary gas. For comparison, a ladle is also preheated using a conventional natural gas burner. Although all samples experience some decarburization, the plasma‐heated samples demonstrate the lowest rate, at 0.14 mm h −1 , compared to 0.20 mm h −1 for the gas‐heated sample. The unexpectedly elevated decarburization in the plasma‐treated bricks is attributed to residual oxygen within the ladle during the trials. Additionally, the plasma‐heated bricks exhibit reduced surface disintegration and superior structural integrity, attributed to partial sintering at temperatures exceeding 1400 °C and enhanced retention of calcium silicates in intergranular regions. These findings indicate that plasma heating provides improved structural preservation of MgO–C linings, even under partially oxidizing conditions, compared to traditional preheating methods.