Aluminium is the third most common element on earth, after oxygen and silicon. As an oxide, it exists everywhere around us: on land, sea, and water. Up to 8% of the earth’s crust is aluminium. Industrial aluminium is enriched from bauxite, which has an aluminium concentration of approx. 25%. Bauxite deposits are found on both sides of the equator. The world has an immeasurable supply of bauxite, and it is increased further by the erosion of rock.
Aluminium has a specific weight of 2.7 kg/dm3, which is less than a third of steel’s specific weight. A steel bar that has similar strength is approx. twice as heavy as an aluminium bar. The lightness and strength of aluminium create significant savings in the transport industry, for example. The use of aluminium in cars, trains, boats, aircraft, and other vehicles creates savings in operating costs and allows for transporting loads.
Aluminium has excellent corrosion resistance, as it forms a hard, dense oxide layer when it comes to contact with the oxygen in the air, thereby preventing further oxidation. This allows aluminium structures to have a long operating life and low need for maintenance. Corrosion resistance can be further improved by anodising, which will also give aluminium a beautiful surface appearance.
It does take a lot of electric energy, approx. 16,000 kWh per tonne, to create aluminium from bauxite. However, new methods are constantly under development, and test facilities have been able to reduce the consumption to
10,000 kWh per tonne. Furthermore, the energy used to produce primary aluminium is “stored” in the aluminium. Melting secondary aluminium only takes 5% of the amount of energy that is required to melt primary aluminium. Aluminium is also a valuable recycled metal that can be easily separated from other metals and used over and over again. Three fourths of all aluminium waste is reused; this is a significant figure in terms of the national economy.