Reduction behavior of barite-containing magnetite pellets in hydrogen

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_xFe_3-xO₄ and Ba-containing silicates in oxidized pellets, which hindered the continuous crystallization of Fe₂O₃. During the reduction process, the reduction of Ba_xFe_3-xO₄ to Ba and Fe by H₂ was challenging, resulting in the formation of BaFeO_2.64. Furthermore, Ba_xFe_3-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 (Fe_xO to Fe), BaFeO_2.64 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.