Heat and Mass Transfer in the Reduction of Single Hematite Pellet by Hydrogen

Abstract

The weight-loss and the variations in temperature at the center and the surface of a spherical hematite pellet were measured during H₂ gas reduction in the bulk gas temperature range of 800°-1050°C.
Two step temperature drop in the center of a pellet was observed in the reduction. It was proved by X ray diffraction that the first step mainly corresponds to the reduction of Fe₂O₃ to Fe_xO, and the second step corresponds to the reduction of Fe_xO to Fe. The surface temperature did not agree with the center temperature during the reduction.
Applying the isothermal model and the non isothermal semi-unsteady model to the measured values, the applicability of the models was investigated. The reduction curves, which were calculated by both models, agreed with the measured values closely. The temperature variation predicted by non isothermal semi-unsteady model agreed with the measured value except the first step.