Bauxite and aluminum oxide

The production process for aluminum is different to that of other metals. Gold, lead, zinc and iron are all metals based on ore, as can be seen in traditional mining operations in Greenland.

Aluminum, on the other hand, is based on an earth metal called bauxite. It is technically possible, but not profitable, to produce aluminum from clay, anorthosite or other minerals.

Bauxite is recovered in open mines, and is commonly occurring, especially in Equatorial regions. The known bauxite reserves are sufficient to sustain at least a further 100 years of mining. Bauxite is either excavated or blasted out, before being transported away via rail, ship or truck.

Bauxite will as a rule be found in a layer below the topsoil. Earlier, the mining of bauxite left considerable scars in the landscape when recovery operations were complete. Today, responsible operators are much better at planning the rehabilitation of the areas in which mining operations will be taking place.

Flora and fauna is surveyed so that later rehabilitation can ensure that the site is returned as close as possible to its original condition. The topsoil with its flora and nutrients is removed and stored, after which the mining of bauxite can begin.

Bauxite is converted at a refinery to aluminum oxide (known as ‘alumina' in the industry) in a chemical process called the "Bayer process". Aluminum oxide is a white powder which is shipped by large vessels to aluminum plants all over the world, where it is used to produce aluminum.

A by-product of the refinery process is so-called "red mud". This is alkaline and has no immediate applications. After being neutralized and dried, it can be used as landfill - in some cases at the same site at which the bauxite was originally removed. The topsoil, which was removed and stored before the mining of the bauxite began, is then laid on top. New vegetation is then planted in this soil, and after just a few years it can be difficult to distinguish this vegetation from the original vegetation in the area.  

The first picture is from 1980 with the bauxite mine in operation. The second picture was taken in 2001 after new forest had been planted. (South Dandalup dam in Australia) (Pic. by Alcoa)

Find mere information om udvinding af bauxit på nedenstående links:

Genanvendelse af bauxit og rehabilitering:
http://www.alupro.org.uk/mining%20and%20production.htm

Rehabilitationsproces brugt af Alcoa i Australien:
http://www.alcoa.com/australia/en/info_page/Mine_rehab.asp

Forbedringer i udvinding af bauxit:
http://www.environment.gov.au/settlements/industry/corporate/eecp/case-s...

Program for rehabilitering:
http://www.doir.wa.gov.au/documents/investment/Bauxite_Mine_Rehabilitati...