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Fe2O3辅助造粒改性强化钛铁矿流态化氢还原

Enhanced fluidized bed hydrogen reduction of ilmenite through granulation modification with Fe2O3

  • 摘要: 为开发钛铁矿高效直接还原技术,本研究创新性地提出采用Fe2O3造粒改性强化其流态化氢还原。通过系统的流态化氢还原试验,揭示了改性对钛铁矿还原行为的作用机制。研究结果表明,Fe2O₃造粒改性具有双重强化效果,既能有效抑制高温下的失流现象,又能显著提高还原速率。改性后的钛铁矿颗粒在940 ℃下氢气中可稳定流化60 min以上,并且还原产物金属化率从12%提升至97%。机制研究表明,在物理效应层面,造粒改性破坏了原始钛铁矿表面新生成的致密铁壳层,同时引入的非黏性组分材料作为物理阻隔层,有效降低了颗粒表面黏性,从而避免了失流的发生。在化学效应层面,造粒改性通过原料微细化,彻底消除了FexMg1-xO·TiO2固溶体形成的“化学屏障效应”。动力学研究表明,造粒改性样品的还原过程符合二维成核与晶粒生长模型。添加的Fe2O3在还原初期即被转化为微小铁晶粒,这些晶粒作为形核位点,极大地促进了FeO·TiO2中铁的析出,使成核速率显著加快。还原反应的表观活化能计算结果显示,Fe2O₃改性样品的活化能(80.47 kJ/mol)低于未改性样品的活化能(94.80 kJ/mol),这证实了其对还原的催化促进作用。通过对不同来源钛铁矿的适用性评估,验证了Fe2O3造粒改性强化还原方法的普适性。本研究为解决钛铁矿流态化氢还原中的失流与还原停滞难题提供了新思路,为实现钛铁矿高效利用奠定了理论基础。

     

    Abstract: To develop efficient direct reduction technology for ilmenite, this study innovatively proposed the use of Fe2O3 granulation modification to enhance its fluidized bed hydrogen reduction. Systematic fluidized bed hydrogen reduction experiments were conducted to investigate the mechanism of modification on the reduction behavior of ilmenite. The results demonstrated that Fe2O3 granulation modification exhibited a dual enhancement effect, as it can effectively inhibited defluidization at high temperatures and significantly increasing the reduction rate. The modified ilmenite particles could be stably fluidized in hydrogen at 940 ℃ for over 60 minutes, and the metallization degree of reduction product is increased from 12% to 97%. Mechanistic studies indicated that, at the level of physical effects, the granulation modification destroyed the dense iron shell newly formed on the surface of raw ilmenite particles. Simultaneously, the introduced non-sticky component materials acted as physical barriers, effectively reducing particle surface stickiness and thereby preventing the occurrence of defluidization. At the level of chemical effects, the granulation modification, through raw material refinement, completely eliminated the "chemical barrier effect" formed by the FexMg1-xO·TiO2 solid solution. Kinetic studies revealed that the reduction process of the granulation-modified samples followed the 2D nucleation and grain growth model. The added Fe2O3 is converted into fine iron grains in the initial reduction stage. These grains acted as nucleation sites, greatly promoting the precipitation of iron from FeO·TiO2 and significantly accelerating the nucleation rate. Calculation of the apparent activation energy for the reduction reaction showed that the activation energy for the Fe2O3-modified samples (80.47 kJ/mol) is lower than that of the unmodified samples (94.80 kJ/mol), confirming its catalytic promoting effect on the reduction. Evaluation of the applicability to ilmenite from different sources verified the universal applicability of the Fe2O3 granulation modification method for enhancing reduction. This study provided a new approach to solving the challenges of defluidization and reduction stagnation in the fluidized bed hydrogen reduction of ilmenite and laid a theoretical foundation for the efficient utilization of ilmenite.

     

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