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Rare metals and rare earths
Rare earths of a lanthanum subset, or lanthanides, are applied in production of permanent magnets, in iron and steel industry and non-ferrous metallurgy, in nuclear, electronic, chemical and other industries. |
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Non-metals
Non-metals are chemical elements that form simple elements with no
metal-specific qualities. Non-metals typically include 22 elements: gases - hydrogen,
nitrogen,
oxygen, fluor, chlorine and inert gases; liquids - bromine; solids - boron, carbon,
silicon, phosphorus,
arsenic, sulphur,
selenium, tellurium, iodine, astatine. |
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Lanthanum is a silver-white metal covered with a greyish oxide layer. Its
physical properties: a melting point is 920, a boiling point is
3469°C; lanthanum
occupies a middle position in tables as for his lasting quality, hardness, electrical
conductivity and other character features. It does not react in the dry air – an
oxide layer protects it safely from oxidation en masse.
It burns down in oxygen if heated up to 450°C with a bright flame (setting
free a lot of warmth). It is being calcinated in a nitric atmosphere with a
resulting black nitride. In chlorine burns lanthanum at room temperature
already, and reacts with à bromine and iodide at heating. Dissolves easily in
mineral acids, does not reacts with alkali liquors. Lanthanum shows valence 3+
in all compounds. Its characteristical feature is how lanthanum reacts with
hydrogen. They start to react at room temperature and set free warmth. They form
non-permanent hydrids, as lanthanum captures hydrogen at the same – the
stronger, the higher the temperature.
Lanthanides react with hydrogen in the same manner. One of them – cerium – is
used as a getter in electro-vacuum industry and in metallurgy.
Pure lanthanum as an alloy component is almost not used, as cheaper and more
available cerium or mischmetal – lanthanum and lanthanides have a similar
alloying effect. Liquated lanthanum is used to extract plutonium out of liquid
uranium
- another point of contact between nuclear and rare earths industries.
Lanthanum oxide La2O3 is more widely used. This white amorphous powder does
not dissolve in water but in acids and has become an important optical glasses
component. Famous Kodak camera objectives contain from 20 to 40% La2O3. Thanks
to the lanthanum additions the camera lens got smaller in size with identical
rapidity, thus providing for a better quality of a colour shooting. It is known,
that lanthanum glasses were applied in the field optical instruments during the
WWII. Best Russian camera objectives, for example «Industar-61ËÇ», are also made
out of lanthanum glass. And one of the best Russian amateur movie cameras is
called simply «Lanthanum»... Recently more and more lab glassware is made of
lanthanum glass. Lanthanum oxide imparts in glasses not only useful optical
properties, but also high thermal stability and acid-resistance. back |
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