Kinetics analysis of direct reduction of iron ore by hydrogen in fluidized bed based on response surface methodology

Abstract

The present research investigates the efficacy of fluidized bed direct reduction of hematite ore using H2 as a metallurgical technology. The study uses response surface methodology (RSM) to obtain the optimal kinetics system for fluidized H2 reduction of hematite ore. The interaction of independent parameters, including reduction time, reduction temperature, fluidizing velocity, and H2 concentration with dependent variables comprising the reduction degree are explored. The final equation for the reduction degree can be established according to RSM analysis. Additionally, for the hematite reduction using H2 in a fluidized, the study investigates the mechanisms and kinetics of isothermal reduction. The result demonstrates that the reduction degree increases with the reduction temperature, fluidizing velocity, and H2 concentration, as well as the reduction mechanisms change with reduction conditions. For instance, an increase in fluidizing velocity and H2 content promotes the transformation of the kinetics model from D3 to D3+F1 and R3+F1 mixed control, respectively. The activation energy for the fluidized H2 reduction of hematite ore to metallic iron Fe ranges from 23.76 to 54.89 kJ/mol.