Vanadium pentoxide

tion capacity in 1994 from all sources, it has been estimated that the world’s production

of vanadium was split as follows: South Africa, 43%; USA, 17%; the Russian Federation,

15%; China, 13%; Venezuela, 4%; Chile, 4%; and others, 4% (Perron, 1994). In 2001,

vanadium production capacity was estimated as follows: South Africa, 44%; the Russian

Federation, 21%; Australia, 10%; USA, 8%; China, 8%; New Zealand, 4%; Kazakhstan,

2%; Japan, 1%; and others, 4% (Perron, 2001).

Available information indicates that vanadium pentoxide is produced by 12 companies

in China, seven companies in the USA, six companies in India, five companies in Japan,

four companies in the Russian Federation, two companies each in Germany and Taiwan,

China, and one company each in Austria, Brazil, France, Kazakhstan, South Africa and

Spain (Chemical Information Services, 2003).

1.2.2

Use

The major use of vanadium pentoxide is in the production of metal alloys. Iron–vana-

dium and aluminium–vanadium master alloys (e.g. for automotive steels, jet engines and

airframes) are produced preferably from vanadium pentoxide fused flakes because of the

low loss on ignition, low sulfur and dust contents, and high density of the molten oxide

compared with powder.

Vanadium pentoxide is also used as an oxidation catalyst in heterogeneous and homo-

geneous catalytic processes for the production of sulfuric acid from sulfur dioxide, phthalic

anhydride from naphthalene or ortho-xylene, maleic anhydride from benzene or n-butane/

butene, adipic acid from cyclohexanol/cyclohexanone, acrylic acid from propane and

acetaldehyde from alcohol. Minor amounts are used in the production of oxalic acid from

cellulose and of anthraquinone from anthracene. Vanadium pentoxide has not found any

significant uses in microelectronics but does have some applications in cathodes in primary

and secondary (rechargeable) lithium batteries and in red phosphors for high-pressure

mercury lamps and television screens. Vanadium pentoxide is used in the industries of

enamelling, electrics and electronics, metallurgy, glass, catalysts, petrochemistry, and paint

and ceramics. It is also used as a corrosion inhibitor in industrial processes for the produc-

tion of hydrogen from hydrocarbons, as a coating for welding electrodes, as ultraviolet

absorbent in glass, as depolariser, for glazes, for yellow and blue pigments, as a photo-

graphic developer, and in colloidal solution for anti-static layers on photographic material.

It is also used as starting material for the production of carbides, nitrides, carbonitrides,

silicides, halides, vanadates and vanadium salts (Woolery, 1997; O’Neil, 2001; ACGIH

Worldwide

®

, 2003; Bauer et al., 2003).

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1.3

Occurrence and exposure

1.3.1

Natural occurrence

Vanadium is widely but sparsely distributed in the earth’s crust at an average concen-

tration of 150 mg/kg and is found in about 80 different mineral ores, mainly in phosphate

rock and iron ores. The concentration of vanadium measured in soil appears to be closely

related to that of the parent rock from which it is formed and a range of 3–300 mg/kg has

been recorded, with shales and clays exhibiting the highest concentrations (200 mg/kg and

300 mg/kg, respectively) (Byerrum et al., 1974; Waters, 1977; WHO, 1988; Nriagu, 1998).

Vanadium is also found in fossil fuels (oil, coal, shale). It is present in almost all coals,

in concentrations ranging from extremely low to 10 g/kg. It is found in crude oil and resi-

dual fuel oil, but not in distillate fuel oils. Venezuelan crude oils are thought to have the

highest vanadium content, reaching 1400 mg/kg. Flue-gas deposits from oil-fired furnaces

have been found to contain up to 50% vanadium pentoxide. In crude oil, residual fuel oil

and asphaltenes, the most common form of vanadium is the +4 oxidation state (Byerrum

et al., 1974; Lagerkvist et al., 1986; WHO, 1988; Nriagu, 1998).

1.3.2

Occupational exposure

Exposure to vanadium pentoxide in the workplace occurs primarily during the pro-

cessing and refining of vanadium-rich ores and slags, during production of vanadium and

vanadium-containing products, during combustion of fossil fuels (especially oil), during

the handling of catalysts in the chemical industry, and during the cleaning of oil-fuelled

boilers and furnaces (Plunkett, 1987). Data on vanadium concentrations in workplace air

and the urine of workers exposed to vanadium in various industries are summarized in

Table 2.

The processing of metals containing vanadium includes chemical treatment and high-

temperature operations. However, only moderate concentrations of vanadium have been

recorded in air in the breathing zone of workers engaged in these operations:

0.006–0.08 mg/m

3

during the addition of vanadium to furnaces, 0.004–0.02 mg/m

3

during

tapping, 0.008–0.015 mg/m

3

during oxyacetylene cutting and 0.002–0.006 mg/m

3

during

arc-welding (WHO, 1988).

In the main work areas of vanadium pentoxide production facilities where vanadium

slag is processed, Roshchin (1968) recorded vanadium concentrations in dust of

20–55 mg/m

3

(reported to be mainly vanadium trioxide) and < 0.17 mg/m

3

vanadium

pentoxide (cited by WHO, 1988). In another study in a vanadium pentoxide production

plant, Kucera et al. (1998) recorded the highest concentration of total air particulates of

271 mg/m

3

at a pelletizer, with a corresponding vanadium concentration of 0.5 mg/m

3

; the

highest concentrations of vanadium were detected in air at a vibratory conveyer and

reached 4.9 mg/m

3

. Similarly high concentrations of vanadium (4.7 mg/m

3

) were reported

in air in the breathing zone of workers in the steel industry (Kiviluoto et al., 1979).

VANADIUM PENTOXIDE

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