Production of aluminum
About 8% of the Earth’s crust is made up of aluminum, making it one of the most common elements. New aluminum is extracted from the clay soil bauxite, which is mined in open-pit mines in a belt around the equator or in Australia. Bauxite is formed by the weathering of silicate materials under tropical conditions. It is a mixture of more or less hydrated oxides of, among others, aluminium, iron and titanium.
The bauxite is crystallized in a refinery into alumina powder (alumina) which is then transported to an aluminium smelter, usually by container ship, using the Bayer method.
An aluminium smelter is very energy-intensive and is therefore often located where there is good access to electricity. In the smelter, the alumina powder is converted into aluminium through a process called electrolysis. The process is started by immersing carbon anodes in liquid alumina powder where large amounts of electricity are drawn through the cell.
The primary aluminum produced has a purity of at least 99.5%. Primary aluminum plants then produce a variety of aluminum alloys by adding different alloying elements.
Good properties increase use
Aluminum profiles are used in many different industries. In construction, for example, aluminum profiles are used in windows, doors, entrances and balconies. The reasons include corrosion resistance and low weight. High strength and low weight contribute to the use of aluminum in load-bearing structures in aircraft, for example. Solar panels also take advantage of the material’s good thermal conductivity.
Aluminum extrusions are widely used in the automotive industry, not least because their low weight means fuel savings over the life of the vehicle. The lower weight of trucks, buses and trains can be used to increase load capacity. Lightweight vehicles also reduce the risk of injury in accidents. The low weight and low maintenance requirements also contribute to an increasing number of ships being built in aluminum.
In the electronics and telecom industry, extrusions are used in base stations, antenna mounts and front panels, among other things. Low weight and good opportunities to build in many functions are natural explanations for the use of aluminum profiles in components for the telecom industry.
One kilogram of aluminum can transmit twice as much electricity as one kilogram of copper. This is why aluminum has largely replaced copper in high-voltage power lines, for example.
Hard facts about aluminum
Aluminum has a density of 2.7 kilograms per cubic decimeter. Iron is about three times heavier. Aluminum has a high conductivity for electricity and heat, about 60 percent compared to electrolytic cups. In contact with oxygen in the air, aluminum forms a protective oxide layer. If the layer is damaged, it is re-formed.
Aluminum alloys have fracture strengths in the range of 70-700 Mpa. It retains its toughness even at temperatures down to -200 degrees and has a relatively large coefficient of elongation.
