Theoretical calculations and thermal experimental study on solid- liquid phase change processes in metallic iron via VIS-NIR spectroscopy prediction

Abstract The melting behavior of scrap steel directly influences the scrap ratio in converters, energy consumption of electric arc furnaces (EAFs), and stability of hot metal pretreatment. Investigating its melting mechanism and detection methods is of great significance for optimizing smelting processes and enhancing resource utilization efficiency. Centering on the high-temperature self-luminescence characteristics of metallic iron—the core component of scrap steel—this study proposes an in-situ measurement method based on visible-near infrared (VIS-NIR) spectroscopy to calculate and analyze the solid-liquid phase transformation process of metallic iron in the molten bath. Through theoretical derivation, the intrinsic correlation between the luminescence intensity of VIS-NIR spectra (during the melting and solidification of metallic iron) and the proportion coefficients of solid-phase and liquid-phase fractions in the molten bath was established. Additionally, a calculation method for determining the liquid-phase fraction proportion in the molten bath via VIS-NIR spectral luminescence intensity was developed, and corresponding experiments were designed to verify the feasibility and calculation accuracy of this method.