<p>To advance green ironmaking and expand the utilization of magnetite with complex gangues, the hydrogen reduction behavior and mechanisms of barite-containing magnetite pellets were investigated. The findings revealed that increasing barite led to the increased amount of Ba<sub><i>x</i></sub>Fe<sub>3−<i>x</i></sub>O<sub>4</sub> and Ba-containing silicates in oxidized pellets, which hindered the continuous crystallization of Fe<sub>2</sub>O<sub>3</sub>. During the reduction process, the reduction of Ba<sub><i>x</i></sub>Fe<sub>3−<i>x</i></sub>O<sub>4</sub> to Ba and Fe by H<sub>2</sub> was challenging, resulting in the formation of BaFeO<sub>2.64</sub>. Furthermore, Ba<sub><i>x</i></sub>Fe<sub>3−<i>x</i></sub>O<sub>4</sub> impeded the reaction between Fe<sub>2</sub>O<sub>3</sub> and H<sub>2</sub>, decreasing the reduction degree and metallization ratio of the pellets. Ba<sup>2+</sup> diffused into the Fe<sub>2</sub>O<sub>3</sub> lattice during oxidation, stabilizing the crystal structure during the initial reduction stage (Fe<sub>2</sub>O<sub>3</sub> to Fe<sub>3</sub>O<sub>4</sub>). In the third reduction stage (Fe<sub><i>x</i></sub>O to Fe), BaFeO<sub>2.64</sub> inhibited the rapid precipitation of metallic iron, thus preventing the abnormal growth of iron whiskers. Consequently, BaSO<sub>4</sub> reduced the reduction swelling index of barite-containing magnetite pellets in hydrogen. These findings offer a theoretical basis for the future implementation of barite-containing pellets in the hydrogen-based shaft furnace direct reduction process.</p>

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Reduction behavior of barite-containing magnetite pellets in hydrogen

  • Ke Ma,
  • Xiao-guang Bai,
  • Zi-jian Su,
  • Yuan-bo Zhang

摘要

To advance green ironmaking and expand the utilization of magnetite with complex gangues, the hydrogen reduction behavior and mechanisms of barite-containing magnetite pellets were investigated. The findings revealed that increasing barite led to the increased amount of BaxFe3−xO4 and Ba-containing silicates in oxidized pellets, which hindered the continuous crystallization of Fe2O3. During the reduction process, the reduction of BaxFe3−xO4 to Ba and Fe by H2 was challenging, resulting in the formation of BaFeO2.64. Furthermore, BaxFe3−xO4 impeded the reaction between Fe2O3 and H2, decreasing the reduction degree and metallization ratio of the pellets. Ba2+ diffused into the Fe2O3 lattice during oxidation, stabilizing the crystal structure during the initial reduction stage (Fe2O3 to Fe3O4). In the third reduction stage (FexO to Fe), BaFeO2.64 inhibited the rapid precipitation of metallic iron, thus preventing the abnormal growth of iron whiskers. Consequently, BaSO4 reduced the reduction swelling index of barite-containing magnetite pellets in hydrogen. These findings offer a theoretical basis for the future implementation of barite-containing pellets in the hydrogen-based shaft furnace direct reduction process.