How is Aluminium made?
How is Aluminium made? About aluminium Aluminium is a soft, non-magnetic metal, which was discovered in 1827. It is strong, lightweight and can be recycled indefinitely. Aluminium is the third most abundant element and the most abundant metal, in the Earth's crust. Its chemical symbol is Al and its atomic number is 13. Mining aluminium Aluminium production begins with bauxite; a clay like soil which is mined from a few metres below the ground. Bauxite is a reddish-brown ore named after Les Baux in France, where it was first discovered. The bauxite is transported to plants where the clay is washed off and the bauxite is passed through a grinder. Alumina, or aluminium oxide, is then separated from the bauxite with a hot solution of lime and caustic soda. This mixture is heated and filtered and the remaining alumina is dried leaving a white powder. Aluminium production The refined alumina is finally transformed into aluminium. Three different raw materials are needed for this process; aluminium oxide, electricity and carbon. Electricity is run between a positive anode and a negative cathode, both made of carbon. The anode reacts with the oxygen in the alumina and forms CO2. The result is liquid aluminium. This liquid aluminium can now be cast into extrusion ingots, sheet ingots or foundry alloys, depending on what it will be used for: • In the aluminium extrusion process, the ingot is heated and pressed through a shaped cutting tool called a die. A basic example of this would be aluminium tubing. • As aluminium is very ductile, it can be rolled in to sheets from 60 cm to 2-6 mm, and the final foil product can be as thin as 0.006 mm. It still will not let light, smell or taste through. Sheet ingots are used to make products including plates, strip and foil. • Aluminium foundry alloys can be cast in different shapes. It is melted and made into, for example, wheel rims or other car parts. The content in foundry alloys can be customised to fit their further use. Recycling scrap aluminium Aluminium can be recycled over and over again with 100 percent efficiency and requires only 5 percent of the energy used to make new aluminium. None of its natural qualities are lost in the recycling process. In theory, there could be a time when we have mined all we need and can just keep re-using the aluminium we already have. Interesting facts: The statue of Anteros in Piccadilly Circus, London, made in 1893, was one of the first statues cast in aluminium. Anteros was the Greek god of requited love. The Rio 2016 Olympic Torch has been made from recycled aluminium. It was used to make the torch lightweight and to improve the experience of the torchbearers. In 1989, just 2% of aluminium cans were recycled. Today, the recycling rate for all aluminium packaging stands at 48% and for aluminium drinks cans, it has reached 60%.