Effect of B 2 O 3 on stability of magnetite oxidation process and hematite reduction process

Abstract

Ludwigite is usually introduced into iron ore concentrate as an additive to enhance the quality of pellets. It is widely accepted that the addition of B₂O₃ can facilitate the growth of hematite grains and enhance the compressive strength of pellets. However, there is currently no consensus regarding the influence of B₂O₃ on the stability of hematite reduction process. This study employed X-ray diffraction, X-ray photoelectron spectroscopy, scanning electron microscopy-energy-dispersive X-ray spectroscopy and Raman spectroscopy to analyse the impact of B₂O₃ contents (0–8 wt.%) and roasting times (10–40 min) on the stability of magnetite oxidation process and hematite reduction process. The results indicate that the growth and crystallisation of hematite are facilitated with the increase of B₂O₃ content and roasting time. The addition of B₂O₃ induced crystal defects in Fe₂O_3. However, the properties in question exhibited a downward trend when B₂O₃ content exceeds 6 wt.%. Furthermore, the reduction degree exhibited a notable decline with an increase of B₂O₃ content. Fe₂O₃ particles are tightly enveloped by a liquid phase rich in boron element, hindering their reduction. Nonetheless, the discovery of the effect of B₂O₃ on hematite reduction process has contributed to the application of ludwigite in pellets.