The reduction of iron oxides by volatiles in a rotary hearth furnace process: Part III. The simulation of volatile reduction in a multi-layer rotary hearth furnace process

For reduction of iron oxides by volatiles from coal, the major reductant was found to be H ₂, and it can affect the overall reduction of iron oxides. In this study, the reduction by actual volatiles of composite pellets at 1000 °C was studied. The volatile reduction of the hand-packed Fe ₂O ₃/coal composite pellet as it is devolatilizing out of the pellet was found to be negligible. However, the reduction of iron oxide pellets at the top layer by volatiles from the bottom layers of a three-layer pellet geometry was observed to be about 15 pet. From the morphological observations of partially reduced pellets and the computed rates of bulk mass transfer, volatile reduction appears to be controlled by a mixed-controlled mechanism of bulk gas mass transfer and the limited-mixed control reduction kinetics. Using the reduction rate obtained from the single pellet experiments with pure hydrogen and extrapolating this rate to an H ₂ partial pressure corresponding to the H ₂ from the volatiles, an empirical relationship was obtained to approximately predict the amount of volatile reduction up to 20 pet.