Hydrogen Plasma Reduction of Iron Oxides

Abstract

We present a study about the reduction of hematite ores by hydrogen plasma. The transformation kinetics and chemical composition are studied over several intermediate states. We find that the reduction kinetics depends on the balance between the input mass and arc powder. For an optimized input mass-arc power ratio, the reduction is obtained within 15 min exposure to the hydrogen plasma. Micro- and nanoscale chemical and microstructure analysis show that the gangue elements partition to the slag oxides, revealed by energy dispersive spectroscopy and atom probe tomography. Si-enrichment was observed in the interdendritic fayalite domains, at the wustite/iron hetero-interfaces and in the oxide particles inside iron. With proceeding reduction, however, such elements are gradually removed from the samples so that the final iron product is nearly free of gangue-related impurities.