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MANFRED ANKE AN. R. ACAD. NAC. FARM.

the 60 known vanadium minerals, only patronite (V2S5), roscoelite
(K (Al, V) 2 [AlSi2 O10] (OH, F)2), carnotite (K U O2 VO4 1.5 H2O) and
vanadinite [Pb5 (VO4)3 Cl] are commercial sources of vanadium. In
none of these ores, vanadium is present with more than 3%. Vana-
dium is often obtained as a by-product of mining for other valuable
materials. One example is carnotite, a uranium-vanadium ore mined
in Australia and the United States (63, 45, 70).

Small amounts of vanadium also occur in fossil fuels from Ve-
nezuela, Angola, California, Iran, Iraq, and Kuwait (> 0.1% up to
1% V). Indonesian, Libyan and West African oils contain but negle-
gible amounts of vanadium (121). Vanadium is concentrated in the
ash when these fuels are burned.

A major commercial use of vanadium has been in steel produc-
tion. Vanadium steel which contains from 0.1-3% vanadium is tough,
strong and heat-resistant, and withstands strain, vibration and shock.

Another important use of vanadium is as a catalyst in a variety
of reactions. Vanadium pent oxide put on an inert support material
is the principal catalyst used in the oxidation of SO2 to SO3 in the
production of sulphuric acid, and for the conversion of naphthalene
into phthalic anhydride during the formation of plastics. In addition,
vanadium oxychloride, tetrachloride and triacetylacetonate are used
as polymerization catalysts in the production of soluble copolymers
of ethylene and propylene. In the reaction vessels, these polymers
are viscous liquids, which can trap the vanadium catalysts and result
in a vanadium content of as much as 500 mg/kg in products used for
the packaging of food and pharmaceuticals. Furthermore, the dispo-
sal of spent catalysts could also be a point source for a contamina-
tion of the biosphere and of food with vanadium (28, 22). Further-
more, vanadium is used for the production of yellow pigments and
ceramics.

Distribution in the Environment

The general abundance pattern of vanadium in common rocks
shows that this ultratrace element is concentrated mainly in mafic
rocks (basalt, gabbro; 200-250 mg V/kg) and shales (100-130 mg/kg).

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