More aluminium is produced each year than any other non-ferrous metal. For this reason, it is difficult to believe that aluminium was only discovered some 200 years ago and has been produced in industrial quantities for only the last 120+ years. Aluminium is the third most abundant element in the earth’s crust. So, why has it not been used for centuries, as has gold or copper? The main answer is that it is never found in its natural form as a pure metal. Aluminium is always locked in, or mixed with, other elements. Aluminium occurs in most rocks, vegetation, soils etc., in this combined form as very stable chemical compounds such as alumino-silicates. The Ten Most Naturally Abundant Elements Element Chemical Symbol % Natural Abundance Oxygen O 47.3 Silicon Si 27.7 Aluminium Al 7.9 Iron Fe 4.5 Calcium Ca 3.5 Sodium Na 2.5 Potassium K 2.5 Magnesium Mg 2.2 Titanium Ti 0.5 Hydrogen H 0.1 Some aluminium-bearing compounds were used by man from the earliest times. Primitive man made pottery from clays containing hydrated aluminium silicate. The Egyptians and Babylonians used aluminium salts for the preparation of dyes and medicines. In 1807, Sir Humphrey Davy, the British scientist, established the existence of the element aluminium. Incidentally he called his elusive element “Aluminum”, the spelling which is still used in the USA. Following Davy’s work, H C Oersted of Denmark isolated small lumps of the metal by heating potassium amalgam with aluminium chloride. By 1845 Wohler, a German scientist, had established a range of properties, including the determination of aluminium’s specific gravity, the property which paved the way for the industrial development of aluminium, its lightness! In France between 1855 and 1886, Henri SainteClaire Deville developed a chemical production process for aluminium production, which together with some other subtle variations in other European countries, formed the basis for production of aluminium as a high-cost, luxury metal in limited quantities. In 1886, “the great leap forward” for the aluminium industry occurred. In this year, Charles Martin Hall in the United States of America and Paul L T Heroult in France, each perfected, quite independently, the electrolytic method for producing aluminium from aluminium oxide (alumina). Their success was compounded in 1888 by the German Karl Bayer improving a cheap production method for alumina from bauxite ore. Almost overnight the price of aluminium plunged from $18 to $4.50 per kg. Aluminium and its attractive properties were now well within the reach of any interested industrialist. Using the new processes every advanced industrial country had established a fledgling industry by the end of the nineteenth century. The Properties Aluminium has been termed “The Magic Metal” or “The Wonder Metal”. The reasons for these accolades lie in the very diverse range of physical, chemical and mechanical properties enjoyed by the metal and its alloys in both cast or wrought forms:- • A key property is low density. Aluminium is only one-third the weight of steel. • Aluminium, and most of its alloys, is highly resistant to most forms of corrosion. The metal’s natural coating of aluminium oxide provides a highly effective barrier to the ravages of air, temperature, moisture and chemical attack, making aluminium a useful construction material. • Aluminium is a superb conductor of electricity. This property, allied with other intrinsic qualities, has ensured the replacement of copper by aluminium in many electrical applications. • Aluminium is non-magnetic and noncombustible, properties invaluable in advanced industries such as electronics or in offshore structures. • Aluminium is non-toxic and impervious, qualities that have established its use in the food and packaging industries since the earliest times.