Reduction Disintegration Behavior of Vanadium Titanomagnetite Pellets in H2–CO–CO2–N2 Mixtures

In this paper, the low–temperature disintegration behavior of vanadium titanomagnetite (VTM) pellets in H2–CO–CO2–N2 mixtures was investigated. Thermodynamic calculations indicated that pseudobrookite (Fe2TiO5) was reduced in the order Fe2TiO5 → Fe2TiO4 → FeTiO3 → FeTi2O5, and the reduction potentials of H2 and CO were mainly depended on the temperature. The experiments were carried out at temperatures of 400–700 °C with H2/(H2 + CO) of 0–1. The experimental results revealed that disintegration mainly occurred over the temperature range of 500–600 °C, because hematite/pseudobrookite was reduced to magnetite/titanomagnetite resulted in the lattice expansion. A maximum RDI−3.15mm of 45.30% was obtained at 550 °C with a H2/(H2 + CO) ratio of 0.26, and the corresponding reduction degree was 13.31%. Moreover, cracks were observed with a H2/(H2 + CO) ratio of 0.20. A certain interaction between H2 and CO reduction exists, owing to their different diffusion coefficients and reduction potentials. The reduction by individual CO gases tended to follow the topochemical reaction mode, whereas the non-topochemical reaction mode was dominant with H2–CO mixtures.