Ann: SRK concludes High-Grade Vanadium Mineralisation at Nelly, page-70

Vanadium Pricing- Bushveld Minerals​

"Vanadium is sold in many different forms - Vanadium Pentoxide, FerroVanadium and Nitrides of Vanadium, such as the trademarked Nitrovan which Vametco produces, all of which can be directly added to steel during production melting.
Vanadium Pentoxide is a specific crystalline compound with the specific formula (V2O5) whilst FerroVanadium is a metal alloy (eg like pewter or brass) that can contain any percentage of Vanadium - typically 35% to 80% for commercial FerroVanadium feedstock for steel strengthening.
Vanadium Pentoxide always contains 56% Vanadium by mass, whilst the Vanadium content of FerroVanadium is indicated in the description, eg FeV(80%). V2O5 is conventionally priced in USD/lb of compound, whilst FerroVanadium is usually priced in USD per Kg of contained Vanadium - (USD/KgV) - so that the prices of FeV(30%) and FeV(80%) can be compared directly.
As a result you might expect the FeV price to be at least 2.2 * 1/0.56 = 3.9 more than the V2O5 one - in practise the ratio appears almost exactly 5, presumably a result of the easier processing of the already steel-like FeV alloy. Nitrovan sells at a premium to FeV because the both the nitrogen and nitrides of Vanadium that it produces appear to be more efficient at strengthening steel than standard FeV.