The Deville process was the first industrial process used to produce alumina 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 (Al(OH)3), boehmite (γ-AlO(OH)) and diaspore (α-AlO(O ...

. The Frenchman

Henri Sainte-Claire Deville Henri is an Estonian, Finnish, French, German and Luxembourgish form of the masculine given name Henry. People with this given name ; French noblemen :'' See the ' List of rulers named Henry' for Kings of France named Henri.'' * Henri I de Mon ...

invented the process in 1859. It is sometimes called the Deville- Pechiney process. It is based on the extraction of alumina with

sodium carbonate Sodium carbonate, , (also known as washing soda, soda ash and soda crystals) is the inorganic compound with the formula Na2CO3 and its various hydrates. All forms are white, odourless, water-soluble salts that yield moderately alkaline solutions ...

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

and coke. The alumina is converted in sodium aluminate. 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 NaOH. It is a white solid ionic compound consisting of sodium cations and hydroxide anions . Sodium hydroxide is a highly caustic base and alkali ...

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 (chemical formula ) is a chemical compound made up of molecules that each have one carbon atom covalently double bonded to two oxygen atoms. It is found in the gas state at room temperature. In the air, carbon dioxide is transpar ...

is bubbled through the solution, causing

aluminium hydroxide Aluminium hydroxide, Al(OH)3, is found in nature 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 ...

to precipitate, leaving a solution of sodium carbonate. The latter can be recovered and reused in the first stage. The aluminium hydroxide is calcined to produce alumina. The process was used in France at

Salindres Salindres () is a commune in the Gard department in southern France. The composer and conductor Roger Dumas (1897–1951) was born, in Salindres. Geography Climate Salindres has a hot-summer Mediterranean climate (Köppen climate classificati ...

until 1923 and in Germany and Great Britain until the outbreak of the Second World War. It has now 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 ...

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