The extraction of vanadium from titanomagnetites and other sources

The commercialisation of vanadium redox flow batteries for large scale electric energy storage and power grid stabilisation is expected to increase the global demand for vanadium in the coming years. Currently most of the vanadium is used in the production of steel alloys and this amount is expected to remain consistent in the years to come. Much of the new demand is expected to come in the form of electrolytes for the application of vanadium to energy storage in the vanadium redox flow batteries and in the form of ultrapure vanadium salts for use a precursor reagents in the production of cathodes for lithium ion batteries. Unlike other metals such as copper, nickel or zinc, vanadium does not form concentrated deposits. Owing to the similarities between the V3+ and Fe3+ cations, vanadium is often found as a minor component of iron minerals. The vanadium mineral coulsonite, FeV2O4 forms series with chromite, FeCr2O4 and magnetite, Fe3O4. Most of the vanadium is produced from titanomagnetites either directly from titanomagnetite ores/concentrates or indirectly from the slag left from smelting titanomagnetite ores. Titanomagnetite ores are associated with mafic igneous rock and have been found in large quantities in Russia, China, South Africa and other countries. Vanadium can also be produced from vanadiferous sandstone, shale and vanadate deposits, though these are of lesser industrial importance compared to titanomagnetites. Vanadium is usually extracted from ores, concentrates and slags by roasting with sodium carbonate or another sodium salt to convert vanadium into water soluble sodium vanadates. This review summarises the established and proven processes for vanadium production as well as some newer processes which have yet to be commercialised.