Reduction Kinectics of Hematite Powders in Non-Equilibrium Hydrogen Plasma

The reduction kinetics of hematite (Fe₂O₃) powders was studied using nonequilibrium hydrogen plasma as reducing agent. Reduction experiments were performed in a DC pulsed plasma reactor, hydrogen flow-rate of 300 cm³/min, at pressure of 400 Pa, reduction times in range 30-120 minutes and in temperatures range 320-380 °C. Fe₂O₃ powders after reduction experiments were characterized by X-ray diffraction, weight loss of oxygen (gravimetric analyses), optic microscope and scanning electron microscope. The results showing that the reduction temperature of 380 °C after 120 min allows obtaining α-iron with a reduction fraction of about 0.93. The powder particles are transformed into two steps: Fe₂O₃→Fe₃O₄→Fe-α. The activation energy experimentally established for the reduction of Fe₂O₃ was about 98.4 kJ/mol.

Keywords:
Hematite reduction; Hydrogen plasma; Solid-state reaction; Activation energy