Kinetic Analysis of the Iron Oxide Reduction Using Hydrogen-Carbon Monoxide Mixtures as Reducing Agent

The kinetics of the reduction of hematite pellets using hydrogen-carbon monoxide mixtures as reducing agent was described by using the “grain model”. This model involves the particle size and the porosity of the pellet as main structural parameters which affect directly the kinetics of the hematite pellets during the reduction process. The predictions of the model were compared with the experimental results. Fired hematite pellets were reduced at 850°C using hydrogen, carbon monoxide and Midrex gas. The weight loss technique was used to follow the reduction process. The reduction of iron oxide pellets using hydrogen or carbon monoxide is a mixed controlled system, where chemical reaction and internal gas diffusion are competing processes during the first stage of the reduction, while internal gas diffusion becomes controlling step at the last stage of the process. The reduction of iron oxide pellets using Midrex gas is a mixed controlled system throughout the whole reduction process.