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Heng Zheng, Oday Daghagheleh, Thomas Wolfinger, Bernd Taferner, Johannes Schenk, and Runsheng Xu, Fluidization behavior and reduction kinetics of pre-oxidized magnetite-based iron ore in a hydrogen-induced fluidized bed, Int. J. Miner. Metall. Mater., 29(2022), No. 10, pp.1873-1881. https://dx.doi.org/10.1007/s12613-022-2511-7
Heng Zheng, Oday Daghagheleh, Thomas Wolfinger, Bernd Taferner, Johannes Schenk, and Runsheng Xu, Fluidization behavior and reduction kinetics of pre-oxidized magnetite-based iron ore in a hydrogen-induced fluidized bed, Int. J. Miner. Metall. Mater., 29(2022), No. 10, pp.1873-1881. https://dx.doi.org/10.1007/s12613-022-2511-7
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预氧化磁铁矿颗粒在氢基流化床中的流化行为及还原动力学研究

摘要: 欧盟(EU)的目标是在2050年实现碳中和,目前,炼钢行业仍然是欧洲主要的二氧化碳排放行业之一,其排放量占欧盟二氧化碳排放总量的4%。因此,为了避免二氧化碳的产生,使用氢气还原铁矿石生产直接还原铁(DRI)受到了越来越多的关注。我们之前的研究显示,在还原过程中由于磁铁矿颗粒表面会形成致密的铁壳,使其表现出较差的流化性和还原性。磁铁矿预氧化处理后,会显著改善它的流化性。本文探究了不同预氧化温度和预氧化程度对磁铁矿颗粒在氢基流化床内流化和还原行为的影响。通过光学显微镜和电子扫描显微镜(SEM)表征了还原后颗粒的显微结构和形貌,并探究了还原过程中的动力学反应机理。结果表明,较高预氧化温度(1000°C)处理后的磁铁矿颗粒表面较为平坦,表现出较好的流化行为。较低预氧化温度(800°C)处理后的磁铁矿颗粒表面形成显著的赤铁矿晶须,其流化性有所降低;但其表现出更好的还原性,特别是在还原后期。磁铁矿的预氧化程度对流化和还原行为没有明显影响。动力学分析表明,较高预氧化温度处理后的磁铁矿颗粒,在还原后期,其还原速率受铁离子扩散速率影响。较低的预氧化温度能改善铁离子的扩散,进而提高还原后期的反应速率。

 

Fluidization behavior and reduction kinetics of pre-oxidized magnetite-based iron ore in a hydrogen-induced fluidized bed

Abstract: The influence of different pre-oxidation temperatures and pre-oxidation degrees on the reduction and fluidization behaviors of magnetite-based iron ore was investigated in a hydrogen-induced fluidized bed. The raw magnetite-based iron ore was pre-oxidized at 800 and 1000°C for a certain time to reach a partly oxidation and deeply oxidation state. The structure and morphology of the reduced particles were analyzed via optical microscope and scanning electron microscopy (SEM). The reaction kinetic mechanism was determined based on the double-logarithm analysis. The results indicate that the materials with higher oxidation temperature and wider particle size range show better fluidization behaviors. The lower oxidation temperature is more beneficial for the reduction rate, especially in the later reduction stage. The pre-oxidation degree shows no obvious influence on the fluidization and reduction behaviors. Based on the kinetic analysis, the reduction progress can be divided into three stages. The reduction mechanism was discussed combing the surface morphology and phase structure.

 

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