Aluminium (Al) – part of a series on metals commonly alloyed with stainless steel to form varying grades of material
Aluminium is a chemical element with an atomic weight of 26.981. On the periodic table, aluminium sits between magnesium and silicon – atomic number 13. It is a silver-coloured metal that is corrosion resistant and very pliable with a melting point of 660 degrees centigrade.
Discovery of aluminium
Scientists in the late 1700s suspected that an unknown metal existed in a salt called alum. They didn’t have a way to extract the metal until a Danish chemist, Hans Christian Oersted, was able to produce a tiny amount of aluminium for the first time in 1824.
The German chemist Friedrich Wöhler developed a more efficient way to refine aluminium, and in 1845 was able to produce small pieces of the metal that allowed him to determine some of the element’s properties.
In 1856, Wöhler’s process was improved upon by the Frenchman Henri Étienne Sainte-Claire Deville. Deville’s new method allowed the first industrial production of aluminium, however, it was challenging to produce and supply was scarce.
Aluminium as status symbol
If you were a head of state in the 1860s and you were considered important enough to receive a dinner invitation from the French Emperor Napoleon III, when you arrived at court, you would have been amazed and honoured to see your food was being served on aluminium plates. If you were a mere Duke, you would have had to make do with gold plates!
Aluminium plates were worth far more than gold plates as gold you could dig up in lumps but aluminium involved a much more complex process of production.
Modern industrial processes have reduced the cost dramatically, but aluminium is still not very efficient to produce and requires a lot of electricity to power the production process. The average aluminium smelting plant, producing around 110 tons per year, uses the same amount of electrical power as a small town.
Global production of aluminium
Most aluminium is extracted from bauxite ore and there are large deposits in China, India, Brazil, Russia and Australia. Australia is one of the world’s largest producers, refining approximately 2 million tons of aluminium per year. This massive output comes at an enormous cost in energy, using 12% of the country’s total electricity supply. The population of Australia is approximately 25 million people, which means aluminium production uses as much power as 3 million people!
The energy cost of aluminium makes it a fantastic material to recycle. Every time we recycle an aluminium car wheel or drinks can we save 95% of the energy required to make the same amount of aluminium from bauxite.
The processes used to produce aluminium are also responsible for various types of waste products. In the United States alone, aluminium plants create a colossal five million metric tons of carbon dioxide each year.
Applications of aluminium
Aluminium’s appeal to industry comes not only from its tensile strength, but also the fact that it is one third as dense as steel making it ideal for the production of lightweight products. Add to this the metal’s incredible resistance to corrosion, and you have an almost perfect material.
For these reasons, aluminium is everywhere today. It is used in the construction of planes, cars, bikes, drink cans and even as a foil for cooking.
A Boeing 777 has a maximum empty operating weight of approximately 304,000 lbs or 137.8 metric tonnes. Over 70 per cent of the aeroplane is made from aluminium and who knows if it would be able to be manufactured with the added weight of other metals.
Aluminium is also used in the PVD industry. Amongst other uses, aluminium can be applied as a thin film to the surface of glass sheets to make mirrors.