Type: Economically
significant examples include patronite (VS4),vanadinite
(Pb5(VO4)3Cl), and carnotite (K2(UO2)2(VO4)2·3H2O).
Much of the world's vanadium production is sourced from vanadium-bearing magnetite
found in ultramafic
gabbro bodies.
Listing description
Vanadium (pronounced /vəˈneɪdiəm/, və-NAY-dee-əm) is the chemical
element with the symbol V and atomic
number 23. It is a soft, silvery gray, ductile transition
metal. The formation of an oxide layer stabilizes the metal against
oxidation. Andrés Manuel del Río discovered vanadium in
1801 by analyzing the mineral vanadinite, and named it erythronium. Four years
later, however, he was convinced by other scientists that erythronium was
identical to chromium. The element was rediscovered in 1831 by Nils Gabriel Sefström, who named it vanadium
after the Scandinavian goddess of beauty and fertility, Vanadis (Freya).
Both names were attributed to the wide range of colors found in vanadium
compounds.
Detailed
description:
Vanadium (pronounced /vəˈneɪdiəm/, və-NAY-dee-əm) is the chemical
element with the symbol V and atomic
number 23. It is a soft, silvery gray, ductile transition
metal. The formation of an oxide layer stabilizes the metal against
oxidation. Andrés Manuel del Río discovered vanadium in
1801 by analyzing the mineral vanadinite, and named it erythronium. Four years
later, however, he was convinced by other scientists that erythronium was
identical to chromium. The element was rediscovered in 1831 by Nils Gabriel Sefström, who named it vanadium
after the Scandinavian goddess of beauty and fertility, Vanadis (Freya).
Both names were attributed to the wide range of colors found in vanadium
compounds.
The
element occurs naturally in about 65 different minerals and in fossil
fuel deposits. It is produced in China and Russia from steel smelter slag; other countries
produce it either from the flue dust of heavy oil, or as a byproduct of uranium
mining. It is mainly used to produce specialty steel alloys such as high
speed tool steels. The compound vanadium pentoxide is used as a catalyst for the
production of sulfuric acid. Vanadium is found in many organisms,
and is used by some life forms as an active center of enzymes.
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History
Vanadium
was originally discovered by Andrés Manuel del Río, a Spanish-born Mexican
mineralogist, in 1801. Del Río extracted the element from a sample of Mexican
"brown lead" ore, later named vanadinite.
He found that its salts exhibit a wide variety of colors, and as a result he
named the element panchromium (Greek: παγχρώμιο "all colors").
Later, Del Río renamed the element erythronium (Greek: ερυθρός
"red") as most of its salts turned red upon heating. In 1805, the
French chemist Hippolyte Victor Collet-Descotils,
backed by del Río's friend, Baron Alexander von Humboldt, incorrectly declared
that del Río's new element was only an impure sample of chromium. Del
Río accepted the Collet-Descotils' statement, and retracted his claim.[1]
In
1831, the Swedish chemist, Nils Gabriel Sefström, rediscovered the
element in a new oxide he found while working with iron ores.
Later that same year, Friedrich Wöhler confirmed del Río's earlier work.[2]
Sefström chose a name beginning with V, which had not been assigned to any
element yet. He called the element vanadium after Old Norse Vanadís
(another name for the Norse Vanr goddess Freyja, whose
facets include connections to beauty and fertility), because of the many
beautifully colored chemical compounds it produces.[2]
In 1831, the geologist George William Featherstonhaugh
suggested that vanadium should be renamed "rionium" after del
Río, but this suggestion was not followed.[3]
The
isolation of vanadium metal proved difficult. In 1831, Berzelius reported the production of the
metal, but Henry Enfield Roscoe showed that
Berzelius had in fact produced the nitride, vanadium
nitride (VN). Roscoe eventually produced the metal in 1867 by reduction of vanadium(II) chloride, VCl2, with hydrogen.[4]
In 1927, pure vanadium was produced by reducing vanadium pentoxide with calcium.[5]
The first large scale industrial use of vanadium in steels was found in
the chassis of the Ford Model T, inspired by French race cars. Vanadium
steel allowed for reduced weight while simultaneously increasing tensile
strength.[6]
Creation
The
stable form of vanadium is created in supernovas
via the r-process.[7]
Characteristics
Vanadium
is a soft, ductile,
silver-gray metal. It has good resistance to corrosion and
it is stable against alkalis, sulfuric and hydrochloric
acids.[8]
It is oxidized
in air at about 933 K (660 °C, 1220 °F), although an oxide layer forms
even at room temperature.
Isotopes
Main article: Isotopes of vanadium
Naturally
occurring vanadium is composed of one stable isotope 51V
and one radioactive isotope 50V. The latter has a half-life of
1.5×1017 years and a natural abundance 0.25%. 51V has a nuclear
spin of 7/2 which is useful for NMR
spectroscopy.[9]
A number of 24 artificial radioisotopes have been characterized, ranging in mass
number from 40 to 65. The most stable of these isotopes are 49V
with a half-life of 330 days, and 48V with a half-life of 16.0 days.
All of the remaining radioactive isotopes have half-lives shorter than an
hour, most of which are below 10 seconds. At least 4 isotopes have metastable
excited states.[9]
Electron capture is the main decay mode
for isotopes lighter than the 51V. For the heavier ones, the most
common mode is beta decay. The electron capture reactions lead to the
formation of element 22 (titanium) isotopes, while for beta decay, it leads to
element 24 (chromium)
isotopes.
Occurrence
Metallic
vanadium is not found in nature, but is known to exist in about 65 different minerals.
Economically significant examples include patronite (VS4),[18]
vanadinite
(Pb5(VO4)3Cl), and carnotite (K2(UO2)2(VO4)2·3H2O).
Much of the world's vanadium production is sourced from vanadium-bearing magnetite
found in ultramafic
gabbro bodies.
Vanadium is mined mostly in South Africa, north-western China, and eastern Russia. In 2007
these three countries mined more than 95 % of the 58,600 tonnes of produced
vanadium.[19]
Vanadium
is also present in bauxite and in fossil
fuel deposits such as crude oil, coal, oil shale and tar sands. In crude oil, concentrations up to 1200 ppm have
been reported. When such oil products are burned, the traces of vanadium may
initiate corrosion
in motors and boilers.[20]
An estimated 110,000 tonnes of vanadium per year are released into the
atmosphere by burning fossil fuels.[21]
Vanadium has also been detected spectroscopically in light from the Sun and some other stars.[22]
Production
Most
vanadium is used as an alloy called ferrovanadium
as an additive to improve steels. Ferrovanadium is produced directly by reducing a
mixture of vanadium oxide, iron oxides and iron in an electric furnace.
Vanadium-bearing magnetite iron ore is the main source for the production of
vanadium.[23]
The vanadium ends up in pig iron produced from vanadium bearing magnetite. During steel production, oxygen is blown into the
pig iron, oxidizing the carbon and most of the other impurities, forming slag. Depending on the
used ore, the slag contains up to 25% of vanadium.[23]
Vanadium
metal is obtained via a multistep process that begins with the roasting of
crushed ore with NaCl or Na2CO3
at about 850 °C to give sodium metavanadate (NaVO3). An
aqueous extract of this solid is acidified to give "red cake", a
polyvanadate salt, which is reduced with calcium metal. As
an alternative for small scale production, vanadium pentoxide is reduced with hydrogen or magnesium.
Many other methods are also in use, in all of which vanadium is produced as a byproduct of
other processes.[23]
Applications
Alloys
Approximately
85% of vanadium produced is used as ferrovanadium
or as a steel
additive.[23]
The considerable increase of strength in steel containing small amounts of
vanadium was discovered in the beginning of the 20th century. Vanadium forms
stable nitrides and carbides, resulting in a significant increase in the
strength of the steel.[25]
From that time on vanadium steel was used for applications in axles, bicycle frames, crankshafts,
gears, and other critical components. There are two groups of vanadium
containing steel alloy groups. Vanadium high-carbon steel alloys containing
0.15 to 0.25% vanadium and high
speed tool steels (HSS) with a vanadium content ranges from 1 % to
5 %. For high speed tool steels, a hardness above HRC 60 can be achieved. HSS steel is
used in surgical instruments and tools.[26]
Other uses
Vanadium(V) oxide is a catalyst in the contact
process for producing sulfuric acid
Vanadium
is compatible with iron and titanium, therefore vanadium foil is used in cladding
titanium to steel.[28]
The moderate thermal neutron-capture cross-section and the short
half-life of the isotopes produced by neutron capture makes vanadium a suitable
material for the inner structure of a fusion
reactor.[29][30]
Several vanadium alloys show superconducting behavior. The first A15 phase
superconductor was a vanadium compound, V3Si, which was discovered
in 1952.[31]
Vanadium-gallium
tape is used in superconducting magnets (17.5 teslas
or 175,000 gauss). The structure of the superconducting
A15 phase of V3Ga is similar to that of the more common Nb3Sn
and Nb3Ti.[32]
Safety
All
vanadium compounds should be considered to be toxic. Tetravalent VOSO4
has been reported to be over 5 times more toxic than trivalent V2O3.[59]
The Occupational Safety and
Health Administration (OSHA) has set an exposure limit of 0.05 mg/m3
for vanadium pentoxide dust and 0.1 mg/m3 for vanadium
pentoxide fumes in workplace air for an 8-hour workday, 40-hour work week.[60]
The National
Institute for Occupational Safety and Health (NIOSH) has recommended that
35 mg/m3 of vanadium be considered immediately dangerous to
life and health. This is the exposure level of a chemical that is likely to
cause permanent health problems or death.[60]
Vanadium
compounds are poorly absorbed through the gastrointestinal system. Inhalation
exposures to vanadium and vanadium compounds result primarily in adverse
effects on the respiratory system. Quantitative data are, however, insufficient to derive a subchronic or chronic
inhalation reference dose. Other effects have been reported after oral or
inhalation exposures on blood parameters, on liver, on neurological development in rats, and other organs.
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