Study of slag formation behavior in iron ore pellets based on thermodynamic calculations and experiments

To investigate the mechanism of slag formation during pellet consolidation, we combined thermodynamic calculations and experimental methods to study the effects of roasting temperature, basicity, and SiO₂ content on slag formation. The results indicate that as the temperature increases, the solid phases clinopyroxene, orthopyroxene, and melilite transform into slag within the pellet. The roasting temperature and basicity of slags formed by different particles varied considerably. At 1250 °C, the slag content is less than 5 % in low-silica fluxed pellets, less than 15 % in medium-silica fluxed pellets, and up to approximately 20 % in high-silica fluxed pellets. Phase diagram analysis showed that CaFe₂O₄ and Ca₂Fe₂O₅ formed in the pellet due to basicity differences SEM-EDS analysis showed that the slag in fluxed pellets primarily comprises the silicates Ca₃Fe₂(SiO₄)₃ and (Mg, Fe)₂SiO₄, as well as ferrate. The slag is distributed in a reticulated pattern within the pellets, with some quartz remaining undissolved in the slag phase and existing independently in pores.