Flake V2O5 98%: Properties, Ferrovanadium Feed and Battery Uses

Flake vanadium pentoxide at 98% minimum purity is the standard commercial form of V2O5 for most industrial buyers. It is a bright orange-yellow to red-brown flake, produced from vanadium-bearing slag or from spent catalyst streams, and it sits at the start of the vanadium value chain: the same material is fed to aluminothermic furnaces to make ferrovanadium, dissolved to make battery electrolyte, and used as a catalyst and a colouring agent.

Composition and Physical Properties

At 98% minimum V2O5, the flake carries roughly 56% vanadium by mass, because vanadium makes up about 56.0% of the mass of pure V2O5. That vanadium figure is the one that should be used in process calculations; the oxide percentage alone does not tell the buyer how much vanadium is being purchased.

Because the melting point is far below steelmaking temperatures, the flake fuses easily and must not be exposed to hot surfaces. Impurity limits, particularly iron, silicon, sulphur and phosphorus, vary with the source of the feedstock and should be stated on the certificate rather than assumed.

Feedstock for Ferrovanadium Production

The largest single use of the flake is as the oxide feed for ferrovanadium. In the aluminothermic process the flake is blended with aluminium and iron-bearing additions, ignited, and reduced to a vanadium-iron alloy that settles into a dense button under an alumina slag. The purity of the flake matters here because the impurity load has to be absorbed by the slag; higher iron and silicon in the feed mean more slag, more aluminium consumption and a lower grade alloy. Suppliers of the FeV50, FeV60 and FeV80 grades described in GB/T 4139 therefore buy flake against tight impurity limits rather than against the oxide percentage alone.

Vanadium Redox Flow Battery Electrolyte

In energy storage, vanadium pentoxide is dissolved to produce the electrolyte for vanadium redox flow batteries, where the same element is used in two oxidation states on either side of an ion-selective membrane. The property that makes the chemistry work is that the electrolyte on both sides is a vanadium solution, so cross-contamination through the membrane does not destroy the cell, and capacity fade from mixing is recoverable by rebalancing the tanks. Electrolyte manufacture is sensitive to impurity levels, and battery grade material is normally specified with tighter limits on iron, silicon, aluminium and chromium than metallurgical grade flake.

Catalyst and Chemical Uses

Vanadium pentoxide is the active phase in the catalyst used to oxidise sulphur dioxide to sulphur trioxide in sulphuric acid plants, and in catalysts for the oxidation of other organic feedstocks. It is also used in the production of vanadium chemicals, in glass and ceramic colouring, and in some oxidation reactions in fine chemicals. In these duties the physical form is less important than the impurity profile, because catalyst poisons such as arsenic and alkalis deactivate the active phase and shorten the catalyst life.

Handling, Packaging and Safety

Vanadium pentoxide dust is toxic if inhaled and irritating to skin, eyes and respiratory tract, so handling areas need local exhaust ventilation, respiratory protection for dusty operations and impermeable gloves. Flake is packed in steel drums lined with a moisture barrier, usually 25 kg or 200 kg net, with an inner liner sealed against humidity because the material is hygroscopic and takes up moisture during storage. The store should be dry, segregated from acids and reducing agents, and clearly marked. Spillages are collected dry and never washed into drains, since dissolved vanadium is mobile in water and is a controlled pollutant in many jurisdictions.

Buying Points for 98% Flake

The purchase specification should carry V2O5 minimum, vanadium content, impurity limits for iron, silicon, aluminium, chromium, sulphur and phosphorus, moisture, and the packing. A certificate of analysis for each lot, backed by periodic independent check analysis, is standard practice for battery and catalyst users, while metallurgical users typically check the vanadium figure and the impurity load that affects slag volume. Because the flake price tracks the vanadium content rather than the oxide content, quotations should always be compared on a per-unit-of-vanadium basis.

Frequently Asked Questions

Q: What is flake V2O5 98% used for?
A: Its main uses are the production of ferrovanadium, vanadium redox flow battery electrolyte, sulphuric acid catalysts, vanadium chemicals, and colouring agents for glass and ceramics.

Q: How much vanadium does 98% V2O5 contain?
A: About 56.0% vanadium by mass, which is the theoretical share of vanadium in pure V2O5, so one tonne of 98% flake delivers roughly 550 kg of contained vanadium.

Q: At what temperature does vanadium pentoxide melt?
A: About 690 C, which is far below steelmaking temperatures, so the flake must be kept away from hot surfaces and process equipment that runs above that level.

Q: Why is flake preferred over powder for battery electrolyte?
A: The flake form generates less airborne dust during handling and dissolves readily in acid, which lowers dust exposure for operators and reduces material loss during electrolyte preparation.

Q: How should the flake be stored?
A: In sealed, moisture-barrier lined drums in a dry store, away from acids and reducing agents, because the material is hygroscopic and takes up moisture that changes the assay and the handling behaviour.

Q: Is vanadium pentoxide hazardous?
A: Yes. Dust is toxic if inhaled and irritates skin, eyes and the respiratory tract, so local exhaust ventilation, suitable gloves and respiratory protection are required for dusty operations, and spills are cleaned up dry.