How Is Aluminium Extracted from Its Ore?

Bauxite Mining

• The largest known bauxite deposits in the world are in Southern Europe and Hungary. While there are some surface deposits, most bauxite is mined underground. Hardened bauxite deposits are blasted loose and washed to remove excess clay.

The Bayer Process

• The Bayer process, a combination of chemical extraction and mechanical separation is used to extract alumina -- the base form of aluminum -- from bauxite. The process takes advantage of the chemical reactivity of aluminum in a simple and inexpensive two-stage process.

Releasing the Alumina from Bauxite

• At the extraction mill, bauxite ore is crushed and dissolved in sodium hydroxide (caustic soda). The solution travels through a series of filters and separators to remove the insoluble particles, leaving the liquified sodium aluminate.

Recovering the Alumina From Solution

• After the insoluble bauxite has been filtered out, the clear sodium aluminate is decanted into a precipitation tank. Pure powdered alumina is mixed in to jump start the chemical reaction to crystallize the alumina held in solution. As the alumina settles to the bottom, the caustic soda is pumped off and reused. The clumps of pure alumina are dried and ground to a fine white powder. The powdered alumina can be refined into metallic aluminum or used in different manufacturing processes.