Aluminium
The history of Aluminium use
Aluminium is now one of the most widely used metals, but one of the hardest to refine due
to it's reactivity with other elements. Even as late as the turn of the century,
Aluminium was considered very valuable and in turn expensive, even more expensive than
gold. In some cultures, when a function was held (for example, a party) by wealthy
people, only the most honored guests would be given Aluminium cutlery, the others had to
make do with gold or silver cutlery.
A Description of the Aluminium ore, including a list of it's contents
Pure Aluminium oxide is known as alumina (Al2O3). This is found as corundum, a
crystalline. Aluminium can also occur as cryolite (Na3AlF6). Traces of other metal oxides
in Aluminium oxide tint it to make it form stones (often precious) for example: chronium
gives a red colour to rubies, and cobalt makes the blue in sapphires.
How Aluminium deposits are formed
Aluminium (like many other metals) is not found in it's pure form, but associated with
other elements in rocks and minerals. An aluminosilicate such as felspar
(KAlSi3O8) is the main constituent of many rocks such as granite, which is quartz and
mica cemented together with felspar. These rocks are gradually weathered and broken down
by the action of carbon-dioxide from the air dissolved in rainwater forming 'kaolin'.
This is further broken down to form other substances, ultimately resulting in the
formation of Aluminium deposits.
Where and how Aluminium is mined?
Aluminium is never found in it's pure state until it has been refined. Aluminium is made
when refining alumina, which is in turn found from the ore 'bauxite'. Bauxite is often
mined in the opencast method.
Aluminium deposits are found in many countries, but the countries with significant
deposits include: Guinea, Jamaica, Surinam, Australia and Russia.
How is Aluminium refined?
One method is the 'electrolytic process'. This is performed when a low voltage current is
passes through a bath containing alumina in the molten form. The alumina is broken down
into Aluminium metal which collects at the bottom of the bath at one electrical pole, the
cathode, and the oxygen which reacts at the other pole, the anode, to give carbon-dioxide
and some carbon-monoxide.
The uses and properties of Aluminium
Aluminium is now the second most widely used metal, after iron. Aluminium and it's
alloys, such as 'duralumin', are used as structural metals for a wide variety of products
from aircraft to cooking utensils. Aluminium foil is used to wrap food and is also being
used to replace copper wire in electrical windings. Aluminium mirrors are used in some
large astronomical telescopes. Some Aluminium ores are found in the form of gems and
precious stones. Aluminium is also used in the making of vehicles such as aircraft due to
it's strength and light weight, but is not used so much in cars due to it's cost.
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