photocourtesy of ABC Rural
Bauxite was first discovered in 1821 by Pierre Berthier in Les Baux, France. It is named for named for Les Baux and was once known as beauxite.
Photo courtesy Arkansas Roadside Travelouge
Bauxite loading Jetty in Weipa, Australia
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1998, 1999, 2000 & 2001 Lighthouse Computer Training & Development
The largest bauxite mine in the world is located in Weipa, Australia. In 1955 geologist Henry Evans realized that the red cliffs in the area were composed of pure bauxite. The mining town of Weipa was built by Comalco and the state government shortly afterwards in order to exploit this area.
Bauxite Mining facilities in Alcan Gove, Arnhem Land, Australia
19 Kilometer conveyor belt takes the bauxite to be processed into alumina.
Photos courtesy of ABC Rural
Photo courtesy Prof. Robert Lancashire, Dept. of Chemistry, University of the West Indies
Bayer Plant in Jamacia
Photo courtesy Professor Jenny Edwards, University of Technology, Sydney. http://www-staff.it.uts.edu.au/~jenny/
Bauxite crusher at Nhunbuy
Bauxite converyor at Nhulunbuy, Australia. Photo courtesy Professor Jenny Edwards, University of Technology, Sydney. http://www-staff.it.uts.edu.au/~jenn
Bauxite Conveyor at Nuhunbuy
photo courtesty Global Alumina
Pipeline in Guinea, Africa.
photo courtesty Global Alumina
Pipeline in Guinea, Africa
photo courtesty Global Alumina
Reclamation Area, Guinea, Africa.
Bauxite is a naturally occuring heterogenous material.
Bauxite photo Courtesy Minerals in Your World! and Pisolitic bauxite photocourtesy of ABC Rural
Bauxite is sometimes thought be a mineral, but it is actually a rock. Bauxite is the primary ore of aluminum. It is formed in tropical climates as the result of chemical weathering; the leaching of silica in aluminum-bearing rocks. It consists of one or more of three aluminum hydroxides minerals, gibbsite, bohmite, diaspore, in varying proportions. Gibbisite is true aluminum hydroxide while bohmite and diaspore are aluminum-oxide hydroxides. Diaspore differs from bohmite in its crystalline structure and necessitates higher temperatures for rapid dehydration. Bauxite also contains varying amounts of iron oxide, silicon oxide, titanium, and small amounts of clay and other silicates.
Bauxite can be very hard, but
is generally fairly soft and clay-like. It comes in a few different
including, brown, tan, yellow, red, white and various
combinations. More often than not it has something of a reddish tint to it
according to amount of iron oxide present. Bauxite
exists in three forms: loose pisolitic, with small and rounded marble-size
grains, cemented pisolitic, with small grains are cemented together, and tubular,
larger chunks with erratic cavities. (Mineral Information
Institute, USGS, 2005, World-Aluminum, 2000.)
Areas with Bauxite
Bauxite mining in Nhulunbuy, Australia. Photo courtesy Professor Jenny Edwards, University of Technology, Sydney. http://www-staff.it.uts.edu.au/~jenny/
One hundred million tons of bauxite are mined each year. Bauxite very easily mined and processed. It generally requires no drilling or blasting because of its relative softness. Bauxite predominantly exists naturally in an acceptable grade, unlike many other metal ores. Enhancing unacceptable grade bauxite by removing clay is also an easy and cheap process. As 80% of the world’s bauxite is gathered from blanket deposits, which are relatively shallow, surface mining is used. The remaining 20% comes from underground pocket deposits located in Southern Europe and Hungary, which require more destructive and problematic excavation techniques.
Bauxite mining in Nhulunbuy, Australia. Photos courtesy Professor Jenny Edwards, University of Technology, Sydney. http://www-staff.it.uts.edu.au/~jenny/
Alumina and Aluminum Production
Aluminum is the second most used metal in the
world. Call for aluminum is high as it suited for many purposes.
It is a strong, resilient
and lightweight material able to conduct heat well. Many materials
in everyday life are made from aluminum, and most materials used
for transportation are made from aluminum. Cars, trucks, boats,
aircrafts, and high voltage power lines are contain aluminum.
Aluminum is also
easily recycled, and loses none of its quality in the recycling
process. About 85% of the world's bauxite goes to make alumina,
to then create aluminum, the remaining percentage is used to create
chemcial, abrasive and refractory products. (Mineral Information
Institute, " date unknown)
The Bayer process is the manner in which bauxite is converted into alumina. Alumina is anhydrous aluminum oxide, a fine white powder. Alumina is a valuble commodity because from alumina one can produce aluminum; 90% of the world’s alumina goes to produce aluminum. The Bayer Process was developed in 1888 by Karl Joseph Bayer. The process was relatively cheap, and caused a substantial boost in aluminum production, making it an everyday commodity. Today the Bayer process is still the most inexpensive method.
Photo courtesy Prof. Robert Lancashire,
Dept. of Chemistry, University of the West Indies
Copied by permission from the "Electrochemistry Encyclopedia" (http://electrochem.cwru.edu/ed/encycl/) on December 4, 2005. The original material is subject to periodical changes and updates.
The process takes place in carbon-lined steel containers and uses the DC, direct current. The average voltage is 5.25 volts and the amperage is high,100,000 to 150,000 amperes. The current flows between a positively charged anode composed of petroleum cake and pitch, and a negatively charged cathode, created by the carbon container. The reaction between the carbon and the oxygen of the alumina produces carbon dioxide and metallic aluminum are produced. Aluminum settles to the bottom and pumped out. (Rocks and Minerals.com, 1999, Lancashire, 1982, Beck, 2001.)
Mining Pollution and Rehabilitation
There are not infinite amounts of bauxite in
an area and thus mining is a temporary process. Once an area has
been mined it is possible
to restore it to some degree. When an area is ready to be rehabilitated,
overburden is first removed from the pit floor, and topsoil returned.
The mining process, however, reduces the water retention ability of
soil, and so even when the topsoil is replaced it is less able to retain
water. Many times rehabilitation efforts cannot restore the total former
diversity of plant and animal life. Great strides, however, can be
made. Past mining operations, predating environmental laws, have devastated
many environments, betraying a lack of scientific knowledge and great
carelessness. There are a great number of abandoned mines. But today,
nearly all mining companies have a rehabilitation plan before they
begin to mine. Additionally most mining companies attempt to preserve
topsoil, so they can return it when the area is done being mined, and
many have their own nursery facilities. (Bergland,
Johanson, 2004, International Council on Mining and Minerals, 2005,
World Aluminum, 2000, Nichols and Nichols, 2003,The European Aluminum
Association, Azom.com, date
unknown, Gardner, date unknown)
Because bauxite mines can be so disruptive to the environment, and also causes large amounts of noise pollution, it is not surprising that many people wouldn't want a bauxite mine in their area. But there are also additional reasons why people have fought to prevent mining. In many of the areas where bauxite is found, there is a history of oppression. In Jamacia, Africa and Australia exploitaton of land and people have become major issues. When bauxite was discovered on sacred Aboriginal land in Australia, for example, it caused great controversy over land rights. But because bauxite mines make money and are economically benefical, their social and religious injuries tend to be overlooked.
Bark Petition 1963
Photo courtesy enair.org
When Europeans first arrived on the shores of Australia they declared the land to be terra nullius, a land of nothing. The Indigenous inhabitants had no rights whatsoever under that concept law, and in most areas were abused and exploited by white settlers, forced into missionary systems and separated from their families. In the remote area of Yolngu in northeastern Arnhem Land, however, although a European mission was established, the Yolngu people had not been “conquered,” and lived in relative peace with the Europeans. In 1960s, however, the Yolngu people discovered French prospectors on their land, who wanted to exploit the bauxite deposits in the area. But under the law of terra nullius, the Aboriginal people had no say in stopping them. In 1963 they petitioned the House of Representatives in Canberra. The petition, written in Gumatj, one of the Yolngu languages as well as English uses their own cultural language of symbols and tradition of bark painting. There a two petitions, one for each of the two Dhuwa and Yirritja moieties. The white government, however, let the company mine the bauxite. The Yolngu took them to court in 1968 and lost. But eventually gained ground with the Aboriginal Land Rights (Northern Territory) Act of 1976, which gave them ownership and land title to lands reserved for them. And the bark petition did succeed in garnering national attention and forcing the white government to recognize the Aboriginal people on their own cultural terms. (Morphy,1998)
Photo courtesy enair.org
USGS, "Bauxite and Alumina Statistics and Information," September
International Council on Mining and Minerals, "Reforesting
After a Bauxite Mine," 2005.
Berglund, Christie, Johanson, Tommy, "Jamaican Deforestation and Bauxite Mining--The Role of Negotiations for Sustainable Resource Use," Minerals & Energy, September 2004, Vol 19 Issue 3, p. 2-14.
Nichols, Owen G., Nichols, Flora M., Restoration Ecology
Beck, Theodore, Electrochemistry Encyclopedia, "Electrolytic Production of Aluminum," October 2001 http://electrochem.cwru.edu/ed/encycl/art-a01-al-prod.htm
World-Aluminum, "Bauxite Mine Rehabilitation",
and "Bauxite Geology," 2000.
Rocks and Minerals.com, "How Aluminum is Produced," May
Morphy, Howard, Aboriginal Art London: Phaidon Press, 1998
Prof. Robert Lancashire,
Dept. of Chemistry, University of the West Indies, "The
Chemistry of Processing Jamaican Bauxite," 1982.
The European Aluminum Association, Azom.com, "Bauxite
Mining and the Environment," date unknown,
FAO Document Repository, Gardner, John, "Rehabilitating
Mines to Meet Land Use Objectives: Bauxite
Mineral Information Institute, "Aluminum and Bauxite," date
Young, B.S., "Jamacia's Bauxite and Aluminum Insdustries," Annals of the Association of American Geographers, September 65, Vol 55, Issue 3, p. 449-464.
Author: Caitlin Lamb
Creation/revision date: December 6, 2005
Copyright © 2005 Earlham College. Revised December 6, 2005 . Send corrections or comments to email@example.com