Comparative study on reduction behaviors of low- and high-grade fired hematite iron ore pellets in coal.

This article focuses on the isothermal reduction behavior of fired low-grade (Ramallakota) and high-grade (Bolani) hematite iron ore pellets in non-coking coal at temperatures of 1123, 1173, and 1223 K. The study found that Ramallakota pellets exhibited higher reduction rates and achieved near-complete reduction faster than Bolani pellets, attributed to their higher porosity and gangue content. X-ray diffraction (XRD) analysis revealed the formation of fayalite (Fe₂SiO₄) and hercynite (FeAl₂O₄) phases in both pellet types, with greater intensities in Ramallakota pellets, while scanning electron microscopy (SEM) showed more iron fiber growth in Bolani pellets. Activation energy values for reduction by coal ranged from 13–14 kJ/mol for Ramallakota and 20–21 kJ/mol for Bolani pellets, indicating that the reduction process is governed by chemical reaction and gas diffusion mechanisms. Both pellet types exhibited normal swelling (≤20%) during reduction, with Bolani pellets showing slightly higher swelling due to increased iron whisker formation.