The Deville–Pechiney process, also known as the Le Châtelier process, was the first industrial process used to produce

alumina Aluminium oxide (or aluminium(III) oxide) is a chemical compound of aluminium and oxygen with the chemical formula . It is the most commonly occurring of several aluminium oxides, and specifically identified as aluminium oxide. It is commonly ...

from

bauxite Bauxite () is a sedimentary rock with a relatively high aluminium content. It is the world's main source of aluminium and gallium. Bauxite consists mostly of the aluminium minerals gibbsite (), boehmite (γ-AlO(OH)), and diaspore (α-AlO(OH) ...

. The Frenchman

Henri Sainte-Claire Deville Henri is the French form of the masculine given name Henry, also in Estonian, Finnish, German and Luxembourgish. Bearers of the given name include: People French nobles * Henri I de Montmorency (1534–1614), Marshal and Constable of France * ...

invented the process in 1859, in collaboration with Louis Le Châtelier. In 1860, Deville sold his aluminium interests to Henri Merle, a founder of Compagnie d'Alais et de la Camargue, later known as

Pechiney Pechiney SA was a major aluminium conglomerate based in France. The company was acquired in 2003 by the Alcan Corporation, headquartered in Canada. In 2007, Alcan itself was taken over by mining giant Rio Tinto Alcan. Prior to its acquisitio ...

. It is based on the extraction of alumina with

sodium carbonate Sodium carbonate (also known as washing soda, soda ash, sal soda, and soda crystals) is the inorganic compound with the formula and its various hydrates. All forms are white, odourless, water-soluble salts that yield alkaline solutions in water ...

. The first stage is the calcination of the bauxite at 1200 °C with

and coke. The alumina is converted in

sodium aluminate Sodium aluminate is an inorganic chemical that is used as an effective source of aluminium hydroxide for many industrial and technical applications. Pure sodium aluminate (anhydrous) is a white crystalline solid having a formula variously given as ...

. Iron oxide remains unchanged and silica forms a polysilicate. In the second stage

sodium hydroxide Sodium hydroxide, also known as lye and caustic soda, is an inorganic compound with the formula . It is a white solid ionic compound consisting of sodium cations and hydroxide anions . Sodium hydroxide is a highly corrosive base (chemistry), ...

solution is added, which dissolves the sodium aluminate, leaving the impurities as a solid residue. The amount of sodium hydroxide solution needed depends upon the amount of silica present in the raw material. The solution is filtered off;

carbon dioxide Carbon dioxide is a chemical compound with the chemical formula . It is made up of molecules that each have one carbon atom covalent bond, covalently double bonded to two oxygen atoms. It is found in a gas state at room temperature and at norma ...

is bubbled through the solution, causing

aluminium hydroxide Aluminium hydroxide, , is found as the mineral gibbsite (also known as hydrargillite) and its three much rarer polymorphs: bayerite, doyleite, and nordstrandite. Aluminium hydroxide is amphoteric, i.e., it has both basic and acidic propert ...

precipitate In an aqueous solution, precipitation is the "sedimentation of a solid material (a precipitate) from a liquid solution". The solid formed is called the precipitate. In case of an inorganic chemical reaction leading to precipitation, the chemic ...

, leaving a solution of sodium carbonate. The latter can be recovered and reused in the first stage. The aluminium hydroxide is

calcined Calcination is thermal treatment of a solid chemical compound (e.g. mixed carbonate ores) whereby the compound is raised to high temperature without melting under restricted supply of ambient oxygen (i.e. gaseous O2 fraction of air), generally fo ...

to produce alumina. The process was used in France at Salindres until 1923 and in Germany and Great Britain until the outbreak of the Second World War. While it has largely been replaced by the

Bayer process The Bayer process is the principal industrial means of refining bauxite to produce alumina (aluminium oxide) and was developed by Carl Josef Bayer. Bauxite, the most important ore of aluminium, contains only 30–60% aluminium oxide (Al2O3), the ...

, an updated version is still in use for processing high-silica bauxite.

References

{{reflist Translated from the French Wikipedia article "Extraction de l'alumine". Industrial processes Aluminium industry fr:Extraction de l'alumine

Further reading

See also

References