Analysis of refractory thermal properties affecting energy demand in secondary steelmaking using transient numerical modelling and ANOVA

Secondary steelmaking involves multiple ladle-based stages in which the steel is subjected to a series of treatments. The ladle consists of an external carpentry, a middle refractory layer, and an inner refractory layer. While the middle layer remains mostly intact, the inner layer, being in contact with the molten steel, gradually thins over time and must be periodically restored. The ladle experiences fluctuating temperatures throughout the process due to heating and cooling. Since the heat transfer through the ladle wall, and the energy demand along the process, is controlled by thermal conductivity ( k ), volumetric heat capacity ( C ), and lining thickness ( s ) the present study aims to evaluate how these variables affect the energy demand ( E ). The analysis of variance has been employed to assess the impact of above-mentioned variables using a transient numerical model covering the complete ladle operating cycle. Although numerical models have been developed for secondary steelmaking, the relative importance of refractory thermal properties on energy demand has not been systematically quantified. The results show that thermal conductivity is the dominant factor affecting energy demand, while volumetric heat capacity and lining thickness also exert statistically significant linear, quadratic, and interaction effects. In addition, the transient simulations reveal that refractory properties govern the number of production cycles required to reach cyclic thermal equilibrium, which varies between three and seven cycles across the investigated design space. The resulting quadratic regression model accurately predicts the steady-state energy demand across the investigated design space, providing a practical tool for refractory material selection and energy optimization in secondary steelmaking.