Molten salt electrochemical production and in situ utilization of hydrogen for iron production

The low voltage electrochemical extraction of iron from iron oxide powder is reported. Hydrogen gas can be generated in molten LiCl at 660 °C by the electrochemical decomposition of steam at a voltage as low as only 0.97 V. Interestingly, individual submicrometer-sized iron oxide particles simply immersed in the melt can directly be reduced to semi-spherical metallic iron particles with a particle size of about 5 μm under the influence of hydrogen gas generated in-situ in the molten salt. The direct reduction of Fe 2 O 3 powder, instead of sintered Fe 2 O 3 pellets, which are commonly used as the cathode in the conventional molten salt electro-deoxidation processes, enhances the simplicity, energy consumption and the reaction kinetics of the molten salt hydrogen reduction process. In this method, the bottom surface of the graphite crucible acts as the cathode, resulting in a high rate of hydrogen cations discharge, hence a high current. The high temperature and low voltage characteristics of this method offer a scalable strategy for direct reduction of metal oxide particles in a green and low-cost way, where there is no requirement for the compaction of metal oxide powders into pellets. The mechanism involved in this hydrogen production and utilization methodology is discussed.