Reduction kinetics of pure and industrial hematite samples with hydrogen in a small fixed bed system

The steel industry is one of the most important industries in the world for manufacturing. Production relies on fossil-based processes mainly conducted in blast furnaces (BF), which use carbon monoxide to reduce the iron oxides in the ores. Globally, the industrial production of iron is responsible for about two gigatons of CO₂ emissions on an annual basis. It is therefore imperative to reduce emissions to make the process more environmentally benign. Using hydrogen instead of carbon monoxide represents a promising solution for reducing greenhouse gas emissions. The present work studies the kinetics and mass transfer phenomena during the reduction of pure and industrial hematite materials with hydrogen in a fixed-bed reactor. The overall reaction displays a complex behavior, which depends on the gas phase used, temperature, surface, and solid-phase phenomena. Significantly different behavior was observed for the different materials studied. To support the interpretation of the reduction data, morphological and chemical-physical characterization was performed on the solid phase at different stages of the reduction process. The information gathered contributes to the understanding of the complex overall reduction kinetics and the differences in the hematite materials of different origins.