Aluminum
Copper, lead, and tin have been used by man for thousands of years. Aluminum, on the other hand, was not discovered until 1808 (over 200 years ago) although early civilizations used aluminum-bearing clays to make pottery, and aluminum salts were used in making dyes and medicines. In 1854, we learned how to produce aluminum commercially. Today, we can't live without it!
Aluminum is a metallic element with the symbol Al. For more information about its atomic structure, weight and more, see our Periodic Chart of the elements. The primary ore of aluminum is bauxite (Note: Bauxite specimens are available on our minerals page). It is plentiful and occurs mainly in tropical and sub-tropical areas such as Africa, the West Indies, South American and Australia. Bauxite contains all kinds of impurities - primarily metals such as iron - but consists of 45 percent to 60 percent aluminum oxide or alumina. Bauxite and alumina used in the US are imported primarily from Jamaica and Australia.
Aluminum, in its metallic form, does not exist naturally. It is found only in combination with other minerals in the form of silicate and oxide compounds which make up about 8 per cent of the earth's crust. Aluminum is the third most common crustal element and the most common crustal metal on earth. These mineral compounds are very stable and it took many years of research to find a way to remove the metal from the ore minerals in which it is found.
Aluminum can be very strong, light (less than one third the specific gravity of steel, copper or brass), ductile and malleable. And, it is an excellent conductor of heat and electricity. Polished aluminum has the highest reflectivity of any material, even more than mirror glass. It can be cast, rolled or extruded into an infinite variety of shapes. It has unique barrier properties as a packaging material, it resists corrosion and it can be recycled-again and again and again, with no loss of quality or properties.
Mixing aluminum with small, often minute, quantities of other materials such as iron, silicon, zinc, copper, magnesium, tin, titamium, lithium, chromium, tungsten, manganese, nickel, and zirconium, it is possible to produce an array of alloys with very different physical properties.
How Aluminum is Produced
Producing aluminum is basically a two stage process consisting of several intermediate steps. First, using several mechanical and chemical stages, bauxite is refined to recover the alumina present using the Bayer Process named after Henry Bayer.
Once the alumina, aluminum oxide trihydrate, is recovered, it can be electrolytically reduced (transformed by electrochemical means) into metallic aluminum. Our Producing Aluminum page has a more detailed look at the process of recovering alumina from bauxite and converting it to aluminum.
The History of Aluminum
The following are important dates in the history of the discovery of aluminum and in the progress of our knowledge and use of this important metal we depend on every day.
- 1808: Sir Humphrey Davy (Britain) discovered the existence of the shiny metal we are so dependent on today and gave it a name - Aluminum.
- 1821: P. Berthier (France) discovered a hard, reddish, clay-like material containing 52 per cent aluminum oxide near the village of Les Baux in southern France. He called it bauxite - after the village. Today, we recognize bauxite as the most common ore of aluminum.
- 1825: Hans Christian Oersted (Denmark) produced very small quantities of aluminum metal by mixing dilute potassium amalgam with anhydrous aluminum chloride. When the two were allowed to react chemically, a residue of slightly impure aluminum was produced.
- 1827: Freidrich Wohler (Germany) developed a method for producing aluminum powder through a chemical reaction between potassium and anhydrous aluminum chloride.
- 1845: Wohler determined the specific gravity of aluminum (2.7) which illustrated one of its unquie physical properties - it was extremely light in weight compared to most metals known at the time.
- 1854: Henri Sainte-Claire Deville (France) create the first commercial process for producing aluminum which - at that time - was more valuable than gold.
- 1855: A bar of aluminum was exhibited alongside the Crown Jewels at the Paris Exhibition.
- 1885: Hamilton Y. Cassner (USA) improved on Deville's process for producing aluminum and 15 tons were produced that year!
- 1886: Two unknown young scientists, Paul Louis Toussaint Heroult (France) and Charles Martin Hall (USA), working separately and unaware of each other's work, simultaneously invented a new electrolytic process (eventually called the Hall-Heroult process) which is the basis for all aluminum production today. They discovered that if they dissolved aluminum oxide (alumina) in a bath of molten cryolite and passed a powerful electric current through it, molten aluminum would be deposited at the bottom.
- 1888: The first aluminum companies were founded in France, Switzerland and the USA
- 1889: Freidrich Bayer (Austria), son of the founder of the Bayer chemical company, invented the Bayer Process for the large scale production of alumina from bauxite.
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