Critical analysis of variable atmosphere gaseous reduction of iron oxides pellets

The paper deals with the analyses of the direct reduction kinetics of industrial iron oxide pellets. Various types of pellets were reduced at different temperatures and pressure (700–1100°C and 1–6 bar) in various atmospheres with different contents of hydrogen and carbon monoxide. The reduction behaviour was described in terms of time to reduction, rate of reduction, and kinetics constant. For those pellets reduced in presence of carbon monoxide, also the carbon percentage in the reduced pellets was taken into account. All the obtained results were analysed through the employment of a commercial multi-objective optimisation tool (modeFrontier) in order to precisely define the weight that each single parameter has on the reduction behaviour of the pellets. The performed analyses allowed also to correlate the different processing parameters and the pellets properties in order to define the kinetics conditions as well as the factors limiting the reduction process.