Mechanism of Iron Powder to Enhance Solid-State Reduction of Chromite Ore

This study investigated the solid-state reduction characteristics of natural chromite ore and the effect of iron powder on the solid-state reduction characteristics of natural chromite ore under isothermal conditions below 1200°C. The enhancement mechanism of iron powder on the solid-state reduction of natural chromite ore was elucidated using optical microscopy, X-ray diffraction (XRD), and scanning electron microscopy-energy dispersive spectroscopy (SEM-EDS). The optimal reduction performance was achieved with a carbon dosage of 20% and an isothermal reduction at 1175°C for 2 hours, resulting in an iron metallization rate of 97.15%. The iron metallization rate of chromite ore exhibited a trend of initially increasing and subsequently decreasing with the addition of iron powder and the optimal iron powder addition determined to be 30%. The iron metallization rate increased from 91.31% (without iron powder) to 96.33% (with 30% iron powder, calcined at 1175°C for 1.5 hours with 20% carbon dosage). Increasing iron podwer dosage from 0 to 30% facilitates the generation of a low-melting Fe-C alloy liquid phase, the in-situ fusion of newly generated iron and the disintegration of chromite spinel particles, enhancing the solid-state reduction of chromite ore. When the iron powder dosage exceeds 30%, the reduction reaction mechanism transitions from multi step reaction to single step reaction, which reduces the disintegration of chromite spinel particles and the enhancement effect of iron powder on the solid-state reduction of chromite ore.