Reduction disintegration behavior of vanadium titanomagnetite pellets in H2–CO–CO2–N2 mixtures

Abstract

In this paper, the low–temperature disintegration behavior of vanadium titanomagnetite (VTM) pellets in H 2 –CO–CO 2 –N 2 mixtures was investigated. Thermodynamic calculations indicated that pseudobrookite (Fe 2 TiO 5 ) was reduced in the order Fe 2 TiO 5 → Fe 2 TiO 4 → FeTiO 3 → FeTi 2 O 5 , and the reduction potentials of H 2 and CO were mainly depended on the temperature. The experiments were carried out at temperatures of 400–700 °C with H 2 /(H 2 + 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 H 2 /(H 2 + CO) ratio of 0.26, and the corresponding reduction degree was 13.31%. Moreover, cracks were observed with a H 2 /(H 2 + CO) ratio of 0.20. A certain interaction between H 2 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 H 2 –CO mixtures. • Thermodynamically, the reduction of pseudobrookite (Fe2TiO5) by H2 and CO is studied. • The disintegration behavior under different conditions is investigated. • The effect of different parameters on disintegration is obtained, and the reason is revealed. • The reaction modes named topochemical and non–topochemical under different gas mixtures are discussed.