Effect of iron ore type on the thermal behaviour and kinetics of coal-iron ore briquettes during coking

Abstract

Effect of three iron ore types (limonite, hematite and oolitic hematite) on the thermal behaviour and reaction kinetics of coal-iron ore briquettes during coking was investigated using the thermal analysis method. The carbonized briquettes were characterized using the XRD and SEM. The results showed that all three iron ores were completely reduced to Fe at the final coking stage. The addition of iron ore to the coal briquette had little influence on the gas yield, but could significantly affect the reaction rate. A synergistic effect of iron ore and coal occurred in the later reaction stage, and the initial temperature of the synergistic effect varied with the type of iron ore in coal-iron ore briquettes. The type of iron ore hardly affected the devolatilization rate of coal-iron ore briquettes, but could greatly influence the reduction rate of iron ore, subsequently the gasification rate of coal char. In addition, the better reduction ability of iron ore could more easily lead to the cracking of coke. When the iron ore was blended into the coal briquette, the reaction kinetics at the first and third reaction stage changed. The three coal-iron ore briquettes had similar weighted average apparent activation energies of 30.67–35.52 kJ/mol.