The Methodology Development for Improving Energy Utilization and Reducing Fluoride Pollution of the Electroslag Remelting Process: A Review

Traditional electroslag remelting (ESR) technology using the slag with a high CaF2 content is faced with a high specific power consumption and fluoride pollution. Under double pressure, it is therefore very important to have a good understanding of the ESR process. The energy utilization, η, of the ESR depends on both the electrical, ηE, and thermal efficiency, ηH. Tailoring slag composition is one of the useful techniques to enhance energy utilization, because slag is very important to generate Joule heat for melting electrodes, control horizontal heat transfer, and maintain uniform distribution of alloy elements from the bottom to top of the remelted ingots in the ESR process. Therefore, herein, the aim is to review the effects of slag composition, especially CaF2 content, and temperature on the electrical conductivity and thermal conductivity, which further influence the heat balance during the ESR process. The volatilization mechanism of the liquid fluoride‐containing slag at an elevated temperature is introduced from the perspective of thermodynamics and kinetics. Meanwhile, some of the recent advances and technology improvements in energy utilization and productivity enhancements for the ESR process are summarized, which provide benefits to achieve sustainable development for the ESR process. Improvement of the physicochemical properties, such as electrical conductivity and thermal conductivity, by adjusting the composition of electroslag remelting (ESR) type slag is one of the direct and effective methods to reduce the energy consumption of the ESR process. Meanwhile, the technological parameters, new electroslag technologies and the methods to improve yield rate of remelted ingots are systemically reviewed.