About UsOur productFrom bauxite to aluminium

The process of making aluminium starts with the mining of bauxite.

Bauxite is the mineral form of aluminium and is made up of approximately 50 per cent alumina. Bauxite deposits are generally found about one metre underground and are around three to four metres deep. Bauxite is mined as small red pebbles called pisolites. Following extraction, any rocks and sticks attached to the bauxite are filtered away, and the bauxite is washed. It then travels along a train or conveyor to stockpiles, ready to be loaded onto ships.

The bauxite used to produce aluminium at BSL is mined in Weipa, Cape York and shipped to Queensland Alumina Limited (QAL) in Gladstone for refining.

Alumina or aluminium oxide is extracted from bauxite through a refining process known as the Bayer process. This takes place over four main stages: digestion, clarification, precipitation and calcination. It takes approximately two tonnes of bauxite to produce one tonne of alumina.

The refining process is as follows:

  • Bauxite is finely ground in mills, then mixed with a caustic soda solution and steam under pressure at high temperatures, which dissolves the alumina content of the bauxite
  • The clarification stage separates the bauxite from the alumina and caustic soda solution. The bauxite settles at the bottom of large tanks and the alumina and caustic liquid is filtered to remove all bauxite traces. The liquid alumina and caustic soda solution is cooled and stirred in open-top tanks until alumina crystals are formed – this can take several days
  • Alumina crystals are washed filtered in precipitation before moving to calcination where they are heated to more than 1,100 degrees centigrade to remove all water content. All that remains is alumina, a fine white powder

The refined bauxite, which is now alumina, is then transported by a conveyor from QAL to BSL for smelting, which is the third stage in the aluminium production process.

The three stages, based in QLD, Australia

Bauxite is mined in Weipa, QLD, Australia.

bauxite

Bauxite is refined to alumina at Queensland Alumina Limited in Gladstone, QLD.

Alumina                                                                                                                                                                                                                                                                           Alumina is smelted into aluminium metal at Boyne Smelters, approximately 20 kms south of Gladstone.

aluminium