Aluminium is the most plentiful metal in the earth's crust. It is found in the form of aluminium oxide in an ore called bauxite (so called because it was first discovered in les Baux de Provence in France). Bauxite also contains titanium, silicon and iron oxides, which give it its red colour.

Alumina and bauxite are the two main raw materials in the aluminium making process.

Around one million tonnes of Australian alumina per year is shipped to Tomago Aluminium via a specially designed berth in the Port of Newcastle.

Bauxite

Chemically, bauxite consists of hydrated aluminium oxide together with oxides of iron silicon, titanium and other elements, and varying small percentages of clay and other silicates. Physically, bauxite can be as hard as rock or as soft as mud. Its colour may be buff, pink, yellow, red, white or various combinations of colours.

Bauxite is the ore that is converted to alumina and then to aluminium.

Australia is the world's leading producer of bauxite, producing 33% of the world’s bauxite production in 2007 (63 MT). Its deposits are among the largest in the world (estimated at more than seven billion tonnes of commercial grade ore),

Second only to Guinea. Bauxite is mined by open cut methods in the Northern Territory, Queensland and in Western Australia.

Alumina

Alumina is made from bauxite at refineries in the Northern Territory, Queensland and Western Australia. Around two and a half tonnes of bauxite are needed to produce one tonne of alumina. Australia is the world's leading producer of alumina, producing 30% of global output.

The majority of the world's alumina production is made by a process known as the “Bayer Process”, which was developed in 1889 by German scientist, Karl Bayer. This complex refining process produces a fine white anhydrous aluminium oxide powder, known as alumina AL203.

The “Bayer Process” begins by grinding the bauxite and mixing it with caustic soda to form slurry. The aluminium component is dissolved out of the bauxite in a series of steam-heated digesters. The liquid passes into large settling tanks where the impurities, including sand and iron oxide, settle out. The aluminate liquor is filtered, cooled and “seeded” with crystals of aluminium hydroxide to aid precipitations of alumina hydrate. The hydrate is then filtered, washed and passed through rotating calcinating kilns operating at high temperatures to produce the white powder known as alumina.

More than 90% of the world's alumina production is used to make aluminium. Small quantities are also used as an abrasive, absorptive and refractory in the chemical ceramics and glass-making industries.