Direct electrochemical conversion of metal oxides to metal by molten salt electrolysis: a review

Little over a decade ago, Professor Derek Fray's group at the University of Cambridge, UK, discovered that a solid metal oxide can be directly reduced to metal by cathodically polarising it in a molten salt electrolytic cell. The simple electrochemical process attracted worldwide attention and significant efforts have been made since then to study and develop the process for production of many metals/alloys from their oxides. The process, with necessary modifications, is being studied and adapted as a head-end step in the pyrochemical reprocessing of spent oxide nuclear fuels. This review discusses the solid-state electro-reduction process, its development and the present status in both public and nuclear domains.