Pure aluminum is a relatively soft, silvery white metal with a dull lustre that is caused by a thin coating of aluminum oxide. It is this coating, which forms almost instantly when the metal is exposed to air, that accounts for its resistance to oxidation. Aluminium's great versatility stems from its excellent properties. It is exceptionally light with a density of 2.7g/ccm (by comparison steel has a density of 7.75g/ccm); has great strength when alloyed; is impervious to rust; and possesses a high degree of conductivity. Aluminium is also ductile, that is, it can be drawn into wires or pressed into sheets or foil making the metal exceptionally versatile.
Aluminium is the most abundant metallic element and the third most abundant of all elements in the Earth's crust, making up 8% of the crust by weight. Only silicon and oxygen are more plentiful.
Today, aluminium outstrips all other nonferrous metals in terms of volume used. Aluminium has numerous applications in the home and industry and is a familiar metal to nearly everyone.
About 85% of all the bauxite mined worldwide is used to produce alumina for refining into aluminium metal. The remaining 15% is used in chemicals, abrasives, refractory products and materials, and aluminium compounds.
The lightness, strength and corrosion resistance of aluminium are important considerations in its application. Metallic aluminium is used in a variety of applications that include transportation, packaging such as beverage cans, building construction and electrical applications.
How is Aluminium made?
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Source: International Aluminium Institute
Aluminium metal is refined from alumina, usually in industrialised countries having good supplies of hydroelectric power. The refining process is known as the Hall-Heroult Process, named after Charles Hall of the U.S. and Paul L.T. Heroult of France, who each independently invented the process in 1866. In this process, alumina (aluminium oxide) is dissolved in molten cryolite (cryolite is an aluminium fluoride mineral, Na3AlF6). The alumina is then separated into its elements by electrolysis.
The largest producers of aluminium metal are Russia, China, the United States and Canada; countries which have abundant hydroelectric power. More than 40 other countries also produce aluminium, including Norway, Iceland, Switzerland, Tajikistan and New Zealand. Other areas of the world with access to abundant and cheap electricity, such as the Middle East, are also expanding their metal production capacities.