Influence of Al2O3-induced MnO2–SiO2 smelting on silicate phase and consolidation behavior of manganese ore sinters

Abstract

Melting of MnSiO3 and Mn2SiO4 in the liquid phase at temperatures above 1250 °C is crucial for the consolidation of low-Al manganese ore. This study examines the influence of Al2O3 content on the sintering consolidation behavior of manganese ore fines, particularly the phase and micromorphological changes in silicate. The low- and high-Al manganese ore fines were compared, and the results suggest that the high-Al manganese ore fines (1.70 wt% Al2O3) obtained sinters with higher strength with lower fuel consumption. Thermodynamic calculations, X-ray diffraction, and scanning electron microscopy/energy-dispersive X-ray spectroscopy analysis reveal that Al2O3, MnO2, and SiO2 reacted to form Mn3Al2Si3O12 during the calcination process. This new phase induced the existing MnSiO3 and Mn2SiO4 eutectic to form a more liquid phase at 1135 °C, which tightly binds the solid particles and strengthens the consolidation of the sinter. Further investigations suggest that above 1100 °C, Mn3Al2Si3O12 can be formed, either in an oxidizing or reducing atmosphere. The higher the Al content, the more silicate liquid phase is found in the sintering system.