Kinetic modeling and parameter estimation of thin-layer iron oxide reduction with hydrogen in a fixed-bed reactor

In recent years, the reduction of iron ores by hydrogen has gained increased attention, as it could significantly reduce greenhouse gas emissions from the metallurgical sector in the near future. In order to enable a rapid technological development in this direction, it is essential to start from the fundamentals of the reduction process, i.e., to investigate the intrinsic kinetics of iron oxide reduction. In this work, an in-depth kinetic investigation of the reduction of pure powdered iron oxides in a packed bed reactor-like system was carried out. The conversion of the solid reactant was followed by measuring the outlet gas composition with the help of rapidly responsive thermal conductivity, and the kinetics of the reduction were mathematically modeled. Based on the assumptions behind the shrinking core model, a mathematical model was developed for a thin fixed-bed reactor that successfully described the experimental data by accurately determining key kinetic parameters. The results show that the different reaction steps are chemically controlled, except for the first step, which is governed by a mixture of internal diffusion and chemical control.