Interface interaction between SiO₂ and magnetite under high temperature: particle migration and inhibition mechanism

Silicon is one of the main gangue components in iron ore, usually in the form of quartz and olivine. Numerous studies have shown that SiO2 has a two-sided effect on the consolidation of pellets during high-temperature oxidation roasting of magnetite. However, it is very difficult to capture the structural evolution and migration mechanisms during high-tem-perature roasting process by existing experimental methods. Therefore, the influence of SiO2 on the consolidation behavior of magnetite was studied through a series of roasting experiments and molecular dynamic simulation. The results show that the consolidation index and particle growth index decrease with the increase in SiO2 content in the particles. At 1573 K, the liquid phase promotes the recrystallization growth of hematite at high temperature. Molecular dynamic study shows that it is difficult for quartz SiO2 to form sintering neck with Fe2O3. When the calcination temperature is higher than 1400 K, the Fe2O3-Fe2SiO4 system produces a considerable sintering neck structure after relaxation. The atomic migration ability of Fe2SiO4 is much higher than that of Fe2O3. The higher atomic migration ability of Fe2SiO4 is the main reason for the formation of the sintering neck.