Vanadium

History

(Scandinavian goddess, Vanadis) Vanadium was first discovered by del Rio in 1801. Unfortunately, a French chemist incorrectly declared that del Rio's new element was only impure chromium. Del Rio thought himself to be mistaken and accepted the French chemists' statement.

The element was rediscovered in 1830 by Sefstrom, who named the element in honor of the Scandinavian goddess, Vanadis, because of its beautiful multicolored compounds. It was isolated in nearly pure form by Roscoe, who in 1867 reduced the chloride with hydrogen.

Vanadium of 99.3 to 99.8% purity was not produced until 1922.[1]

Sources

Vanadium is found in about 65 different minerals among which are carnotite, roscoelite, vanadinite, and patronite, important sources of the metal. Vanadium is also found in phosphate rock and certain iron ores, and is present in some crude oils in the form of organic complexes. It is also found in small percentages in meteorites.

Commercial production from petroleum ash holds promise as an important source of the element. High-purity ductile vanadium can be obtained by reduction of vanadium trichloride with magnesium or with magnesium-sodium mixtures.

Much of the vanadium metal being produced is now made by calcium reduction of V2O5 in a pressure vessel, an adaption of a process developed by McKechnie and Seybair.[1]

Properties

General
Name : vanadium
Symbol : V
Atomic Number : 23
Chemical Series : Transition Metal
Block, Period : 5, 4
Appearance : silvery gray metallic
Atomic Properties
Atomic Weight : 50.9415
Covalent Radius (pm) : 125
Physical Properties
Matter : solid
Density (kg/) : 6110
Hardness (Mohs): 7.0
Melting Point (K) : 2175
Boiling Point (K) : 3682
Evaporation Heat (kJ/mol) : 0.452
Fusion Heat (kJ/mol) : 20.9
Specific Heat (J/(kg*K) ) : 490
Miscellaneous
Electrical Conductivity (/m ohm) : 4.89
Thermal Conductivity (W/(m*K) ) : 30.7

Pure vanadium is a bright white metal, and is soft and ductile. It has good corrosion resistance to alkalis, sulfuric and hydrochloric acid, and salt water, but the metal oxidizes readily above 660oC.

The metal has good structural strength and a low fission neutron cross section, making it useful in nuclear applications.[1]

Isotopes

Natural vanadium is a mixture of two isotopes, 50V (0.24%) and 51V (99.76%). 50V is slightly radioactive, having a half-life of > 3.9 x 1017 years. Nine other unstable isotopes are recognized.[1]

Uses

Vanadium is used in producing rust resistant and high speed tool steels. It is an important carbide stabilizer in making steels.

About 80% of the vanadium now produced is used as ferrovanadium or as a steel additive. Vanadium foil is used as a bonding agent in cladding titanium to steel. Vanadium pentoxide is used in ceramics and as a catalyst.

It is also used to produce a superconductive magnet with a field of 175,000 gauss.[1]

Handling

Vanadium and its compounds are toxic and should be handled with care. The maximum allowable concentration of V2O5 dust in air is about 0.05 (8-hour time-weighted average - 40-hour week).[1]

Notes

[1] From Los Alamos National Laboratory's Chemistry Division Website