Geology Reference
In-Depth Information
obtained as a byproduct of iron, uranium, phosphor, copper, lead, zinc or titanium
ores.
This element finds extensive use in the manufacture of special steels as it forms
stable carbides and nitrides that provide considerable strength. Vanadium steel
alloys (1-5% V ) are used for high speed tools in axles, crankshafts and gears. Ti-
tanium alloys with aluminium (6%) and vanadium (4%) are used for aerospace
applications.
The chemical industry profits from vanadium compounds' ability to change ox-
idation states, leading to their use as catalysts. Vanadium oxides catalyse the
production of sulphuric acid in the contact process and are also involved in the
catalytic reduction of nitrogen oxides in power plant emissions. Vanadium salts are
also used as yellow and orange pigments that can replace the ecologically dangerous
chromium pigments.
B.2.73 Wolfram (Tungsten)
Wolfram, also known as tungsten, is a transition metal, which has the highest
melting point of any metal. Hence, it is used in the filaments of incandescent light
bulbs, in electric contacts and arc-welding electrodes. It imparts great strength to
alloys including that of steel. Tungsten is also used in X-ray tubes and in microchip
technology. Its most important application though is in the manufacture of cement
carbide, since its main component is wolfram carbide (WC).
There are several minerals of wolfram, the most important ones are scheelite
and wolframite.
B.2.74 Ytterbium
Ytterbium is a rare earth element found with other REE in several rare minerals
such as gadolinite, monazite and xenotime. It is most often recovered commer-
cially from monazite sand used in certain steels for improving the grain refinement,
strength and other mechanical properties of stainless steel.
Some ytterbium alloys have been used in dentistry. Like other REE, it can
be used to dope phosphors, or for ceramic capacitors and other electronic devices.
Ytterbium increases its electrical resistivity at high stress and is thus used in stress
gauges for monitoring ground deformations such as those that occur during earth-
quakes (For more details, see Sec. B.2.68).
B.2.75 Yttrium
Yttrium is a silver-metallic rare earth metal which naturally occurs with heavy
rare earths. This is due to its chemical similarities to the lanthanides, between
gadolinium and erbium. Even if it is the 28th most abundant element in the Earth's
crust, it is widely dispersed and its current applications highly exceed its global
production.
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