Melting and crystallization behavior of silico-ferrite of calcium and aluminum (SFCA) in iron ore sintering: Roles of varying Fe/Al molar ratio and cooling rate

Increasing Fe/Al molar ratio promoting better assimilation of iron ore powder. • The inter-particle bonding ability of SFCA can be evaluated by osmotic pressure. • Lower Fe/Al ratios coupled with slower cooling promote dendritic SFCA formation. • Higher crystallization rate enhances hardness but reduces elastic modulus of SFCA. • Optimizing SFCA micromechanical properties through Fe/Al ratio and cooling rate. Iron ore sintering represents a critical agglomeration process wherein the silico-ferrite of calcium and aluminum (SFCA) phase governs the consolidation behavior and final product quality. In this study, the effects of Fe/Al molar ratio (4.53 to 12.27) and cooling rate (50 to 200 °C/min) on SFCA characteristics in Fe 2 O 3 -CaO-SiO 2 -Al 2 O 3 systems were systematically investigated by using X-ray diffraction, in situ thermal analysis platform, Raman spectroscopy, Scanning electron microscope (SEM) and nanoindentation. Increasing Fe/Al ratio could reduce the liquid phase formation temperature and enhance the melt fluidity, promoting better assimilation of iron ore powder. Meanwhile, optimal inter-particle bonding occurred with optimal osmotic pressure achieved at 300 to 350 s of high-temperature maintenance. Higher cooling rates significantly accelerated crystallization kinetics, leading to refined microstructures with dispersed crystalline phases. Notably, lower Fe/Al ratios coupled with slower cooling promoted dendritic SFCA formation, while accelerated crystallization enhanced hardness but compromised elastic modulus. The influence of slower cooling rates on crystallization rate and micromechanical properties was more pronounced in sintered liquid phases with lower Fe/Al molar ratios. These findings provide crucial insights into the fundamental mechanisms governing SFCA formation in iron ore sintering, offering practical strategies for optimizing sintering parameters through precise regulation of chemical composition and thermal conditions. Download: Download high-res image (126KB) Download: Download full-size image