Effect of nano-SiO2 addition on the apparent viscosity of Fe2O3 particles
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摘要: 借鑒流體黏性的表征方式,引入粉體顆粒表觀黏度的概念表征粉體顆粒間的相互作用力,基于能量耗散原理,利用旋轉黏度計測定了含SiO2納米添加劑的Fe2O3顆粒在不同溫度條件下的表觀黏度.實驗結果表明,Fe2O3顆粒表觀黏度隨溫度升高而增大,納米SiO2的加入使顆粒表觀黏度明顯降低,主要原因是納米SiO2對Fe2O3顆粒形成了包覆,抑制了顆粒間的團聚和燒結.此外,本研究利用微型流化床研究了含納米SiO2的Fe2O3顆粒在流化還原過程中發生黏結失流的過程,進一步驗證了納米SiO2對Fe2O3顆粒表觀黏度的影響.結果表明,加入納米SiO2顯著提高了還原樣品的金屬化率,延長了還原過程中的黏結時間;掃描電鏡分析表明納米SiO2有效包覆在Fe2O3顆粒表面,降低了鐵原子的擴散活性,并充分阻隔新鮮鐵之間的接觸,抑制新鮮鐵的燒結,從而導致Fe2O3顆粒之間難以形成黏結點,由此證明納米SiO2對流化床內Fe2O3顆粒的還原過程中的黏結失流具有明顯抑制作用.Abstract: 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.
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Key words:
- nano-silica /
- iron oxide /
- apparent viscosity /
- fluidized reduction /
- sticking
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參考文獻
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