Effect of nano-SiO₂ addition on the apparent viscosity of Fe₂O₃ particles

With the depletion of high-quality ore resources at home and abroad, the supply of domestic coking coal resources has become increasingly tense, and research on the non-blast furnace ironmaking technology has become even more necessary. The fluidized ironmaking technology can directly utilize powder ore, does not need to consume coke, and has good prospects for development. However, the sticking problem limits the fluidized ironmaking technology. Therefore, the sticking mechanism of particles must be explored, and inhibition measures must be put forward. Although many researchers at home and abroad have performed numerous studies on the influencing factors and inhibiting technologies of the sticking problem, the quantitative characterization and analysis of the sticking degree have rarely been studied. Similar to the fluid viscosity, the apparent viscosity of solid particles was introduced herein to characterize the interaction force between particles. The apparent viscosity of Fe₂O₃ particles with nano-SiO₂ were measured by a rotational viscometer based on the principle of energy dissipation. The results indicate that the apparent viscosity of Fe₂O₃ particles increases with the increasing temperature and significantly decreases when nano-SiO₂ is added. This result could be explained by the nanoSiO 2 coating on the particles inhibiting the agglomeration and sintering among particles. Sticking occurred during the fluidization process. The reduction of Fe₂O₃ particles was investigated by a micro-fluidized bed to verify the effect of nano-SiO₂ on the apparent viscosity of Fe₂O₃ particles. Consequently, the results show that adding nano-SiO₂ to the Fe₂O₃ particles can effectively improve the metallization rate and prolong the sticking time in the reduction process. Furthermore, the scanning electron microscopy analysis exhibits that the nano-SiO 2 coating on Fe₂O₃ particles reduces the diffusion activity of the iron atoms, blocks the contact between fresh iron, and inhibits the sintering of fresh iron, thereby making it difficult to form sticking points. In conclusion, adding nano-SiO₂ to Fe₂O₃ particles can effectively inhibit sticking in the reduction process of the fluidized bed.