Abstract

The secondary metallurgy is a high energy-intensive step in steelmaking process as it requires an accurate adjustment of the composition and temperature of the molten metal during the ladle refining. In this context, the steel ladle lining plays an important role on the process energy consumption, as the refractory thermal properties are strictly related to the ladle ability to keep the molten metal temperature constant. Aiming to improve the process energy efficiency, reducing both the costs and the environmental effects, many studies have been recently carried out, using numerical simulation tools, analytical models and experimental data, to predict the heat transfer mechanisms in the ladle operational cycle. Nevertheless, few of them highlight the refractory role on those mechanisms. Based on a transient numerical analysis using temperature dependent refractory properties, the present work proposes a holistic process view in order to help the refractory design of steel ladles, according to their saving energy capability. The numerical model was developed using a commercial software (Abaqus) to simulate one ladle cycle (pre-heating, holding and waiting steps). Distinct working layer materials and the presence of an insulating one were considered and investigated. The temperatures of molten metal and ladle shell were compared to evaluate the energy efficiency of the different lining configurations. The numerical simulation results indicated that the configurations containing an insulating layer significantly reduced the energy needed for reheating the molten bath. The distinct refractory working layer materials also had a great impact in the process energy consumption due to their different thermal conductivity and heat capacity. In summary, saving energy in steelmaking is a key factor to improve the process efficiency and, when supported by a thermal and energy balance tool, new materials and optimized lining configurations could be explored, leading to a higher performance of the steel plants.