Scholarlink

<p>Magnesia fluxed pellets possess advantages such as a high iron grade and a low energy consumption in smelting, making their production instrumental in increasing the ratio of pellet utilization in blast furnaces and reducing the carbon emissions of ironmaking systems. In this study, the evolution of the mineral composition and phase structure during the roasting process of magnesia fluxed pellets was investigated <i>via</i> a stage-segmentation method. Additionally, the segregation and distribution mechanism of Mg among various mineral phases was elucidated through first-principles calculations. The results indicate that the porosity of the magnesia fluxed pellets gradually decreases during roasting. The hematite content initially decreases and then increases, whereas magnetite and silicate phases begin to emerge after the roasting zone is entered. The grain size of magnetite increases during roasting, with its content first increasing and then decreasing, whereas the silicate phase gradually diminishes. The interaction of Mg atoms with Fe<sub>3</sub>O<sub>4</sub> crystal surfaces is stronger than that with calcium silicate, with an adsorption energy of − 3.84 eV for Fe<sub>3</sub>O<sub>4</sub> compared with − 2.02 eV for calcium silicate. Consequently, Mg primarily resides in the magnetite phase, with a small fraction distributed in the silicate phase. At the end of the preheating stage, the microstructure of the magnesia fluxed pellets appears granular. After the roasting stage is entered, hematite begins to decompose into magnetite under the influence of MgO. As the roasting process progresses, hematite and magnetite particles recrystallize and grow in three-dimensional space, accompanied by the generation of liquid phases and the interconnection of pores. Recrystallization and growth of hematite mainly occur during the roasting stage. During the equalization and cooling stages, some magnetite is oxidized into hematite, leading to fragmentation of the magnetite grains and a reduction in the grain size. An increase in the MgO content increases the porosity of the pellets and the magnetite phase content, which hinders recrystallization of hematite. Consequently, the pellet strength decreases as the MgO content increases.</p>

错误：搜索内容不能为空，请输入英文关键词
错误：关键词超出字数限制，请精简
高级检索

Mineral Phase Structure Evolution During the Roasting Process of Magnesia Fluxed Pellets

  • 期刊论文

  • 发表日期：

    2025年5月20日

查看全文
  • Xuheng Chen,
  • Wenkang Lin,
  • Changyu Li,
  • Yun Huang,
  • Bin Wang,
  • Shufang Lu,
  • Shijing Chen,
  • Wei Wang

摘要

Magnesia fluxed pellets possess advantages such as a high iron grade and a low energy consumption in smelting, making their production instrumental in increasing the ratio of pellet utilization in blast furnaces and reducing the carbon emissions of ironmaking systems. In this study, the evolution of the mineral composition and phase structure during the roasting process of magnesia fluxed pellets was investigated via a stage-segmentation method. Additionally, the segregation and distribution mechanism of Mg among various mineral phases was elucidated through first-principles calculations. The results indicate that the porosity of the magnesia fluxed pellets gradually decreases during roasting. The hematite content initially decreases and then increases, whereas magnetite and silicate phases begin to emerge after the roasting zone is entered. The grain size of magnetite increases during roasting, with its content first increasing and then decreasing, whereas the silicate phase gradually diminishes. The interaction of Mg atoms with Fe3O4 crystal surfaces is stronger than that with calcium silicate, with an adsorption energy of − 3.84 eV for Fe3O4 compared with − 2.02 eV for calcium silicate. Consequently, Mg primarily resides in the magnetite phase, with a small fraction distributed in the silicate phase. At the end of the preheating stage, the microstructure of the magnesia fluxed pellets appears granular. After the roasting stage is entered, hematite begins to decompose into magnetite under the influence of MgO. As the roasting process progresses, hematite and magnetite particles recrystallize and grow in three-dimensional space, accompanied by the generation of liquid phases and the interconnection of pores. Recrystallization and growth of hematite mainly occur during the roasting stage. During the equalization and cooling stages, some magnetite is oxidized into hematite, leading to fragmentation of the magnetite grains and a reduction in the grain size. An increase in the MgO content increases the porosity of the pellets and the magnetite phase content, which hinders recrystallization of hematite. Consequently, the pellet strength decreases as the MgO content increases.