Hydrogen Reduction of Iron Oxide Powder in Thin Layers

Abstract

The steel industry is responsible for a very large environmental impact because more than 70% of the production of iron is done in blast furnaces, where the reduction of iron oxides (ore) is performed with carbon monoxide obtained from coke and coal. Their partial oxidation produces CO used to reduce the iron oxides, simultaneously yielding huge amounts (approximately 2GT/a) of CO₂. It is necessary to find new alternatives to decarbonize the steelmaking process. The present work studies the reduction kinetics of iron oxides using hydrogen as a reductant. The overall reaction displays complex behavior that explains the versatile and partly contradictory interpretations found in the literature on hydrogen reduction of iron oxides. Experiments in thin layers of powder were performed under various experimental conditions to investigate the kinetics with both pure iron oxide and an industrial feedstock. To support the interpretation of the data, morphological and chemical-physical characterization was performed, and a comparison between pure hematite and commercial ironmaking pellets was reported.