Vanadium is the 22nd most abundant element in the earth’s crust, occurring more than 65 minerals . Vanadium resources globally are estimated at
63 million metric tons with the majority located in China, Russia, South Africa and Australia . North America, Canada, Brazil, Finland and Madagascar also have vanadium deposits.
World vanadium reserves (that form part of the identified vanadium resource that meets specified minimum physical and chemical criteria related to current mining and production practices) are estimated at about 15 million metric tons and it is likely sufficient to meet vanadium needs into the next century at the present rate of consumption. More than 95% of global Reserves are in China, Russia, South Africa and Australia.
Titaniferous magnetite is the most important source for vanadium presently accounting about 85% of the current world V2O5 production. This iron ore typically contains 1.0% to 1.5% V2O5.
Titaniferous magnetite ore is mined in South Africa and China and processed for vanadium extraction. Tianiferous magnetite ore is also processed in steelmaking operations in China, Russia and South Africa. A duplex BOF process in the steelmaking shop yields a vanadium rich slag that can be converted into V2O5 via hydrometallurgical processing.
Vanadium is present in crude oil in the Caribbean basin, parts of the Middle East and Russia, as well as in tar sands in western Canada. Coal in parts of China and the USA contains vanadium. During the refining or burning of these energy sources a vanadium bearing ash, slag, spent catalyst or residue is generated which can be processed for vanadium recovery.
Other minor contributors to vanadium production today include roscoelite – a mineral processed in alumina production primarily in India which yields a vanadium bearing sludge, carnotite – a vanadium bearing uranium mineral mined in the western USA, and V bearing iron sands used in steelmaking in New Zealand.
Primary titaniferous magnetite mines account for about 26% of global vanadium production. Coproduct steelmaking slag resulting from the processing of titaniferous magnetite ore supports about 59% of global vanadium. Secondary sources supply about 15% of today’s vanadium production.Ref:  Byron Capital Markets Industry Report – Vanadium: the Supercharger, November 12 2009;  US Geological Survey, Minerals Commodity Summaries, Vanadium January 2010
In addition to the extensive reserves of titaniferous magnetite containing vanadium in Australia, China, Russia and South Africa there are several other deposits of magnetite and other materials containing vanadium from which it could be extracted in the future.
There are magnetite deposits in Brazil, Chile, Canada, Australia, Madagascar and Malaysia. Shale oil and tar sands containing vanadium are present in North America and Queensland, Australia. Vanadium coproduct production from uranium mining in North America and Australia will contribute to vanadium supplies in the future.
Vanadium from the titaniferous magnetite ores of Russia and China and South Africa is extracted as a co-product in steelmaking. In China and Russia the iron is produced in a blast furnace but in South Africa the iron is produced by a process involving the pre-reduction of the magnetite with powdered coal in a rotary kiln followed by reduction in a submerged arc electric furnace. Vanadium bearing coproduct slag is generated during steel production from iron sands in New Zealand in a process similar to the South African process.
The iron from these operations contains about 1.5% vanadium which is removed as slag by low temperature treatment with oxygen. In China this is carried out by spray refining, while in South Africa it is done in a shaking ladle and in Russia a special oxygen steel converter is used.
The slag from South Africa contains up to 25% V2O5 whereas the slag from China and Russia contains between 14% and 22%. The V2O5 is extracted from the slags by a roast-leach process in which the slags are roasted in kilns or in multi-hearth furnaces with sodium carbonate, chloride or sulphate (or lime in Russia). This produces sodium vanadates which are leached into an aqueous phase with water. Ammonium vanadates are precipitated from this solution by addition of ammonia and sulphuric acid to control the pH.
The ammonia is removed and the vanadate converted to various oxides by heating under controlled conditions which are varied according to the oxide required. Fused flake V2O5 is produced by decomposing the vanadates in a furnace and melting the resulting V2O5 to liquid phase and then casting onto a chilling wheel. Vanadium oxide powders are produced by the solid state decomposition of the vanadates in a controlled environment. In some cases liquid-liquid ion exchange/solvent extraction processes are utilized to produce high purity vanadium oxide powders.
Vanadium oxides are used for the production of ferrovanadium and vanadium-aluminium alloys required for the addition of vanadium to steel and titanium respectively. Ammonium vanadates and high purity vanadium oxide powders are used for the production of downstream vanadium chemicals.
Vanadium from the Colorado carnotite ore is extracted as a co-product during uranium production. The ore is treated with sulphuric acid to dissolve the vanadium and uranium. The uranium and vanadium are separated from the liquid by solvent extraction followed by a liquid-liquid ion exchange process which separates the uranium leaving the vanadium in the acid solution. This is subsequently oxidised and removed from the organic salts with soda ash. Vanadium polyvanadate is precipitated by the addition ammonium sulphate.
Vanadium, from oils in which it is present, is obtained by various routes. It is present in the coke produced in the Flexicoke process used in Venezuela for the upgrading of heavy crude oils. Vanadium from this coke leached into solution with sulphuric acid and ammonium vanadates are precipitated.
Vanadium bearing oil based fuels are burnt in the boilers of electric power generating plant and vanadium is left in the fly ash and boiler slags. Vanadium in these ashes and slags is recovered by the same process as for vanadium coming from Flexicoke. Ashes and slag are also converted directly to ferrovanadium (40%V grade) via silicon reduction in an electric furnace.
Spent nickel-molybdenum and cobalt-molybdenum catalysts are treated pyrometallurgically to solubilise the metals present (V, Co, Ni, Mo), separate the metals and precipitate them as salts (including vanadates) before converting to oxides.
Vanadium is added to steel as a ferroalloy. Ferrovanadium is available in alloys containing 40%, 60% or 80% vanadium. The 60% and 80% grades are mostly produced by the aluminothermic reduction of vanadium oxides in the presence of steel scrap or by direct reduction in an electric furnace. The 40% grade is produced from slag and other vanadium products by the silicon reduction process.
Vanadium additions to titanium alloys are made with aluminium-vanadium master alloys which are also produced by aluminothermic reduction of high purity vanadium oxides.
Acknowledgement to Vanitec.