Electro-reduction of hematite using water as the redox mediator

Abstract

The primary production of iron from its oxides, about 1.6 billion tons per annum, alone is several times greater than the production capacity of all other metals together. This massive production is conventionally achieved by carbothermal reduction causing several million tons of greenhouse CO₂ emissions every year, with catastrophic environmental consequences. Here, we present a green, efficient and economical molten salt route for the electrolytic production of iron from iron oxide (hematite, Fe₂O₃). The dissolution of water in molten LiCl causes the formation of hydrogen cations in the melt, which can be discharged on cathodically polarized solid iron oxide pellets immersed in the melt, leading to the reduction of Fe₂O₃ of metallic iron and the regeneration of water. The Fe₂O₃ pellet was thoroughly reduced to iron under 1.4 V within 5 h, considerably faster and more energy efficient than the current electro-deoxidation methods available. The feasibility of the water induced electrochemical reduction of metal oxides is confirmed using Fe₂O₃, but this novel methodology should be applicable to a broad range of metal oxides.