It is less than 200 years since the element aluminium was discovered and only approximately an aeon since a viable production process was established, and today more aluminium is produced each year than all other non-ferrous metals combined.
Aluminium is the third most abundant element of the Earth’s crust, behind that of oxygen and silicon. Of the metallic elements, it is the most abundant, 7.3% by mass of the total crust. Due to aluminium’s high affinity to bind with oxygen, it is not found in naturally occurring in its elemental state, but only in combined forms such as oxides or silicates.
Aluminium bearing compounds have been used by man from the earliest times of human history. Ancient Greeks and Romans used aluminium salts as dyeing mordants and as astringents for dressing wounds. The metal originally obtained its name from the Latin word for alum, alumen. The name alumina was proposed by L. B. G. de Moreveau in 1761 for the base in alum, which was positively shown in 1787 to be the oxide of a yet to be discovered metal. In 1808, Humphry Davy identified the existence of the metal, which he at first termed alumium and later aluminium.
The metal was first produced in 1825 (in an impure form) by Danish physicist and chemist Hans Christian Ørsted. He reacted anhydrous aluminium chloride with potassium amalgam and yielded a lump of metal looking similar to tin. Friedrich Wöhler was aware of these experiments and cited them, but after redoing the experiments of Ørsted he concluded that this metal was pure potassium. He conducted a similar experiment in 1827 by mixing anhydrous aluminium chloride with potassium and yielded aluminium.
Wöhler is generally credited with isolating aluminium, but also Ørsted can be listed as its discoverer. Further, Pierre Berthier discovered aluminium in bauxite ore and successfully extracted it. Frenchman Henri Etienne Sainte-Claire Deville improved Wöhler's method in 1846, and described his improvements in a book in 1859, chief among these being the substitution of sodium for the considerably more expensive potassium.
Before the Hall-Héroult process was developed, aluminium was exceedingly difficult to extract from its various ores. This made pure aluminium more valuable than gold. Bars of aluminium were exhibited at the Exposition Universelle of 1855, and Napoleon III was said to have reserved a set of aluminium dinner plates for his most honoured guests.
Aluminium was selected as the material to be used for the apex of the Washington Monument in 1884, a time when one ounce (30 grams) cost the daily wage of a common worker on the project; aluminium was about the same value as silver.
The Cowles companies supplied aluminium alloy in quantity in the United States and England using smelters like the furnace of Carl Wilhelm Siemens by 1886. Charles Martin Hall of Ohio in the U.S. and Paul Héroult of France independently developed the Hall-Héroult electrolytic process that made extracting aluminium from minerals cheaper and is now the principal method used worldwide.
The Hall-Héroult process cannot produce Super Purity Aluminium directly. Hall's process, in 1888 with the financial backing of Alfred E. Hunt, started the Pittsburgh Reduction Company today known as Alcoa. Héroult's process was in production by 1889 in Switzerland at Aluminium Industrie, now Alcan, and at British Aluminium, now Luxfer Group and Alcoa, by 1896 in Scotland.
The success of the Hall-Héroult process was advanced when Karl Bayer, an Austrian, invented an improved process for making aluminium oxide (alumina) from bauxite. These inventions sealed the fate of aluminium by 1890 the cost of aluminium had tumbled some 80% from Deville's prices.
Despite all the excitement and scientific successes, the pioneers quickly found that, once viable production was established, selling the output was very difficult indeed. Markets did not exist and had to be developed from scratch and the manufacturing industry, used to more traditional metals, needed to acquire specific skills to successfully fabricate aluminium end products.
The first target markets involved the substitution of copper, brass and bronze. Despite the initial difficulties, world production of aluminium soared from less than 200 tonnes in 1885 to approximately more than 35 million tonnes in 2009. The prophecies of Dickens, Verne and Richards about aluminium have come true!
Text: International Aluminium Institute, European Aluminium Association, History Of Aluminium, Wikipedia
Photos: E S F Science Blog, Construction Week Online