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Bauxite

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This article is about the ore. For the town in Arkansas, seeBauxite, Arkansas.
Reddish-brown bauxite
Bauxite withUS pennyfor comparison
QEMSCANmineral maps of bauxite ore-formingpisoliths

Bauxite(⫽ˈbɔːksaɪt⫽) is asedimentary rockwith a relatively highaluminiumcontent. It is the world's main source ofaluminiumandgallium.Bauxite consists mostly of the aluminiummineralsgibbsite(Al(OH)3),boehmite(γ-AlO(OH)) anddiaspore(α-AlO(OH)),mixedwith the twoiron oxidesgoethite(FeO(OH)) andhaematite(Fe2O3), the aluminiumclay mineralkaolinite(Al2Si2O5(OH)4) and small amounts ofanatase(TiO2) andilmenite(FeTiO3orFeO·TiO2).[1][2] Bauxite appears dull inlusterand is reddish-brown, white, or tan.[3]

In 1821, theFrenchgeologistPierre Berthierdiscovered bauxite near the village ofLes BauxinProvence,southernFrance.[4][5]

Bauxite extraction and refining has numerous negative consequences to the environment and to people. The negative impacts are well documented and there are many examples from all over the world. These impacts include the destruction of the environment, water, and airsoil pollutionand soil degradation.[6][7]

Formation[edit]

Bauxite with core of unweathered rock

Numerous classification schemes have been proposed for bauxite but, as of 1982,there was no consensus.[8]

Vadász (1951) distinguishedlateriticbauxites (silicate bauxites) fromkarstbauxiteores(carbonate bauxites):[8]

In the case ofJamaica,recent analysis of the soils showed elevated levels ofcadmium,suggesting that the bauxite originates fromMiocenevolcanic ashdeposits from episodes of significant volcanism in Central America.[9]

Production and reserves[edit]

Main article:List of countries by bauxite production
World bauxite production in 2005
One of the world's largest bauxite mines inWeipa,in northernQueensland,Australia

Australia is the largest producer of bauxite, followed byGuineaandChina.[10]Bauxite is usuallystrip minedbecause it is almost always found near the surface of theterrain,with little or nooverburden.Increasedaluminium recycling,which requires lesselectric powerthan producing aluminium from ores, may considerably extend the world's bauxite reserves.

2023 Bauxite production and reserves (thousandtons)[11]
Country Production Reserves
World 327,000 30,000,000
Australia 110,000 3,500,000
Guinea 82,000 7,400,000
China 60,000 710,000
Brazil 35,000 2,700,000
Indonesia 23,000 1,000,000
India 22,000 650,000
Jamaica 7,700 2,000,000
Russia 6,100 480,000
Kazakhstan 5,800 160,000
Vietnam 4,000 5,800,000
Saudi Arabia 4,000 180,000
Greece 1,800 Undisclosed
Guyana 1,700 850,000
Other countries 9,000 4,570,000

Aluminium production[edit]

See also:Aluminium § Production and refinement
Bauxite being loaded at Cabo Rojo,Dominican Republic,to be shipped elsewhere for processing; 2007
Bauxite being digested by washing with a hot solution of sodium hydroxide at 175 °C (347 °F) under pressure at National Aluminium Company, Nalconagar, India.

As of 2010,approximately 70% to 80% of the world's dry bauxite production is processed first intoaluminaand then into aluminium byelectrolysis.[12]Bauxite rocks are typically classified according to their intended commercial application: metallurgical, abrasive, cement, chemical, and refractory.[13][14]

Bauxite ore is usually heated in a pressure vessel along with asodium hydroxidesolution at a temperature of 150 to 200 °C (300 to 390 °F). At these temperatures, thealuminiumis dissolved assodium aluminate(theBayer process). The aluminium compounds in the bauxite may be present asgibbsite(Al(OH)3),boehmite(AlOOH) ordiaspore(AlOOH); the different forms of the aluminium component will dictate the extraction conditions. The undissolved waste,bauxite tailings,after the aluminium compounds are extracted containsiron oxides,silica,calcia,titaniaand some un-reactedalumina.After separation of the residue by filtering, pure gibbsite is precipitated when the liquid is cooled, and then seeded with fine-grainedaluminium hydroxide.The gibbsite is usually converted intoaluminium oxide,Al2O3,by heating in rotary kilns or fluid flash calciners to a temperature in excess of 1,000 °C (1,830 °F). This aluminium oxide is dissolved at a temperature of about 960 °C (1,760 °F) in moltencryolite.Next, this molten substance can yield metallic aluminium by passing anelectric currentthrough it in the process of electrolysis, which is called theHall–Héroult process,named after its American and French discoverers.

Prior to the invention of this process, and prior to theDeville process,aluminium ore was refined by heating ore along with elementalsodiumorpotassiumin avacuum.The method was complicated and consumed materials that were themselves expensive at that time. This made early elemental aluminium more expensive thangold.[15]

Maritime safety[edit]

As abulk cargo,bauxite is a Group A cargo that may liquefy if excessively moist.[16]Liquefactionand thefree surface effectcan cause the cargo to shift rapidly inside the hold and make the ship unstable, potentially sinking the ship. One vessel suspected to have been sunk in this way was theMSBulk Jupiterin 2015.[17]One method which can demonstrate this effect is the "can test", in which a sample of the material is placed in a cylindrical can and struck against a surface many times.[18]If a moistslurryforms in the can, then there is a likelihood for the cargo to liquefy; although conversely, even if the sample remains dry it does not conclusively prove that it will remain that way, or that it is safe for loading.

Source of gallium[edit]

Bauxite is the main source of the rare metalgallium.[19]

During the processing of bauxite toaluminain theBayer process,gallium accumulates in thesodium hydroxideliquor. From this it can be extracted by a variety of methods. The most recent is the use ofion-exchange resin.[20]Achievable extraction efficiencies critically depend on the original concentration in the feed bauxite. At a typical feed concentration of 50 ppm, about 15 percent of the contained gallium is extractable.[20]The remainder reports to thered mudandaluminium hydroxidestreams.[21]

Bauxite is also a potential source forvanadium.[22]

Socio-ecological impacts[edit]

Mineração Rio do Norte (MRN) Bauxite Mine

The social and environmental impacts of bauxite extraction are well documented. Most of the world's bauxite deposits can be found within 1 to 20 metres (3 ft 3 in to 65 ft 7 in) of the earths surface.[6][23]Strip miningis the most common technique used for extracting shallow bauxite.[23]This process involves removing the vegetation, top soil, andoverburdento expose the bauxite ore.[23]The overlying soil is typically stockpiled in order torehabilitatethe mine once operations have finished.[23]During the strip mining process, the biodiversity and habitat once present in the area is completely lost and the hydrological and soil characteristics in the region are permanently altered.[23]Other environmental impacts of bauxite mining includesoil degradation,air pollution,andwater pollution.[6]

Red mud[edit]

Main article:Red mud

Red mud is a highlyalkalinesludge, with a high pH around 13, that is a byproduct of theBayer process.[24]It contains several elements such assodium aluminoscilicate,calcium titanate,monohydrate aluminium, and trihydrate aluminium that do not break down in nature. When improperly stored, red mud can contaminate soil and water, which can result inlocal extinctionof all life. Red mud was responsible for killing all life in the Marcal River in Hungary after a spill occurred in 2010. When red mud dries, it turns into dust that can cause lung disease, cancer and birth defects.[24]

Conflicts[edit]

In the tropical regions of Asia, central Africa, South America and northern Australia, there has been an increase of bauxite mines on traditional and indigenous lands.[23]This has resulted in a number of negative social impacts on local and indigenous peoples.[7]In theBokéRegion of Guinea, there has been a significant increase in bauxite mining pressure on the local population. This has resulted in potable water issues, air pollution, food contamination, and landexpropriationdisputes due to improper compensation.[7]

Bauxite mining has led to protests, civil unrest, and violent conflicts in Guinea, Ghana, Vietnam, and India.[24]

Guinea[edit]

Guinea has a long history of mining related conflicts between communities and mining companies.[citation needed]Between 2015 and 2018, new bauxite mining operations in theBokéRegion of Guinea have caused in 35 conflicts which include movements of revolts and road blockades. These conflicts have resulted in the loss of human life, the destruction of heavy machinery, and damage to government buildings.[citation needed]

Ghana[edit]

TheAtewarange in Ghana, classified as an ecologically important forest reserve with an area of 17,400 hectares (43,000 acres), has been is a recent site of conflict and controversy surrounding baxuite mining.[25]The forest reserve is one of the only two upland evergreen forests in Ghana, and makes up a significant portion of the remaining 20% of forested habitat left in Ghana. The Atewa range falls under the jurisdiction ofAkyem AbuakwaTraditional Area and is overseen by the king known as Okyenhene.[25]In 2013, an NGO called A Rocha Ghana held a summit with the forestry and water resource commission, the minister of lands, the minister of the environment, and other important stakeholders. They came to the conclusion that no future government should mine bauxite in the region because the reserve is environmentally and culturally significant.[25]In 2016, the government along with NGO's began the process of upgrading the reserved to a national park. However, that year an election took place, and before it became official, the newly elected National Patriotic Party (NPP) rejected the plan.[25]In 2017, the government of Ghana signed aMemorandum of Understandingwith China to develop new bauxite mining infrastructure in Ghana. Although there was no official plan to mine the Atewa Forest Reserve, tensions between local communities, NGO and the government began to rise. In 2019, tensions began to reach a peak when the government presented theGhana Integrated Bauxite and Aluminium Development Authority Actthat would create the legal framework required to develop and establish an integrated bauxite industry.[25]In may of that year, the government began drilling deep holes in the reserve. These actions sparked several protests, including a 95-kilometre (59 mi) march from the reserve to the presidential palace, an informational billboard campaign led by A Rocha Ghana, and a youth march.[25]In 2020, A Rocha Ghana also sued the government over the drilling in the reserve after they failed to provide a statement explaining their actions.[25]

Vietnam[edit]

In early 2009, the Vietnamese Government proposed a plan to mine remote regions of the central highlands.[24]This proposal was highly controversial and sparked a nationwide debate and the most significant domestic conflict since theVietnam War.Government scientists, journalists, religious leaders, retired high level state officials, andGeneral Võ Nguyên Giáp,the military leader of anti-colonial revolution, were among the many people across Vietnamese society who opposed the governments plans.[24]In an attempt to stop the spread of information across the globe, the government banned domestic reporters from reporting on bauxite mining. However, reporters turned to Vietnamese language websites and blogs where the reporting and discussion continued. On April 12, 2009, several well-respected Vietnamese scholars started a petition against the mining of bauxite that was signed by 135 accomplished and well known "Intellectuals".[24]This petition helped unite the scattered anti-bauxite movement into a unified opposition against the state. These acts of governmental defiance were met with repressive state actions. Many domestic online reporters were arrested, and legislative action was taken to repress scientific research.[24]

India[edit]

Most of India's bauxite ore reserves, which are among the top ten largest in the world, are located on tribal land.[26]These tribal lands are densely populated and home to over 100 million Indigenous Indian peoples. The mountain summits located on these lands act as a source of water and greatly contribute to the regions fertility.[26]The Indian bauxite industry is interested in developing this land for aluminum production, which poses great risk to the terrestrial and aquatic ecosystems. Historically, the Indigenous peoples living on these lands have shown resistance to development, and oppose any new bauxite mining projects in the area. This has led to violent conflicts between Indigenous communities and police.[26]On December 16, 2000, police killed three Indigenous protestors and wounded over a dozen more during a protest over a bauxite project in the Kashipur region.[26]

See also[edit]

References[edit]

  1. ^Geological Survey (U.S.) (1986).Geological Survey Professional Paper.U.S. Government Printing Office. p. 2-PA20.
  2. ^"The Clay Minerals Society Glossary for Clay Science Project".Archived fromthe originalon April 16, 2016.
  3. ^"Aluminum".Minerals Education Coalition.
  4. ^P. Berthier (1821)"Analyse de l'alumine hydratée des Beaux, département des Bouches-du-Rhóne"(Analysis of hydrated alumina from Les Beaux, department of the Mouths-of-the-Rhone),Annales des mines,1st series,6:531-534. Notes:
    • In 1847, in the cumulative index of volume 3 of his series,Traité de minéralogie,French mineralogistArmand Dufrénoylisted the hydrated alumina from Les Beaux as "beauxite". (See: A. Dufrénoy,Traité de minéralogie,volume 3 (Paris, France: Carilian-Goeury et Vor Dalmont, 1847),p. 799.)
    • In 1861, H. Sainte-Claire Deville credits Berthier with naming "bauxite", on p. 309, "Chapitre 1. Minerais alumineux ou bauxite" of: H. Sainte-Claire Deville (1861)"De la présence du vanadium dans un minerai alumineux du midi de la France. Études analytiques sur les matières alumineuses."(On the presence of vanadium in an alumina mineral from the Midi of France. Analytical studies of aluminous substances.),Annales de Chimie et de Physique,3rd series,61:309-342.
  5. ^Burgess, N. (October 26, 2015)."March 23, 1821: Bauxite Discovered".Earth.RetrievedJuly 31,2021.
  6. ^abcKy, Lee; Ly, Ho; Kh, Tan; Yy, Tham; Sp, Ling; Am, Qureshi; T, Ponnudurai; R, Nordin (December 1, 2017). "Environmental and Occupational Health Impact of Bauxite Mining in Malaysia: A Review".IIUM Medical Journal Malaysia.16(2).doi:10.31436/imjm.v16i2.346.ISSN2735-2285.
  7. ^abcDibattista, Ilaria; Camara, Abdoul Rachid; Molderez, Ingrid; Benassai, Edoardo Maria; Palozza, Francesco (2023). "Socio-environmental impact of mining activities in Guinea: The case of bauxite extraction in the region of Boké".Journal of Cleaner Production.387:135720.Bibcode:2023JCPro.38735720D.doi:10.1016/j.jclepro.2022.135720.
  8. ^abBárdossy, G. (1982).Karst Bauxites.Amsterdam: Elsevier. p. 16.ISBN978-0-444-99727-2.
  9. ^Muhs, Daniel R.; Budahn, James R. (2009). "Geochemical evidence for African dust and volcanic ash inputs to terra rossa soils on carbonate reef terraces, northern Jamaica, West Indies".Quaternary International.196(1–2): 15.Bibcode:2009QuInt.196...13M.doi:10.1016/j.quaint.2007.10.026.
  10. ^"Bauxite and Alumina 2020 Annual Publication"(PDF).U.S. Geological Survey.January 2020.Archived(PDF)from the original on October 9, 2022.RetrievedJune 29,2020.
  11. ^"Bauxite and Alumina 2023 Annual Publication"(PDF).U.S. Geological Survey.January 2024.RetrievedMarch 20,2024.
  12. ^"BBC - GCSE Bitesize: Making aluminium".Archived fromthe originalon February 25, 2018.RetrievedApril 1,2018.
  13. ^Australia, Geoscience (December 19, 2023)."Bauxite".Geoscience Australia.RetrievedMarch 6,2024.
  14. ^"Bauxite and Alumina Statistics and Information | U.S. Geological Survey".www.usgs.gov.RetrievedFebruary 8,2024.
  15. ^Michael Quinion (January 23, 2006)."Aluminium versus aluminum".Worldwidewords.org.RetrievedDecember 19,2011.
  16. ^"IMSBC CODE GROUP A CARGOES".Baltic and International Maritime Council.RetrievedNovember 21,2021.
  17. ^"Bulk Jupiter sinking: A stark reminder of bauxite cargo risks".Safety4Sea.September 20, 2019.RetrievedNovember 21,2021.
  18. ^"What a Can Test Can Do".February 8, 2021.RetrievedNovember 21,2021.
  19. ^"Compilation of Gallium Resource Data for Bauxite Deposits Author: USGS"(PDF).Archived(PDF)from the original on October 9, 2022.RetrievedDecember 1,2017.
  20. ^abFrenzel, Max; Ketris, Marina P.; Seifert, Thomas; Gutzmer, Jens (March 2016). "On the current and future availability of gallium".Resources Policy.47:38–50.Bibcode:2016RePol..47...38F.doi:10.1016/j.resourpol.2015.11.005.
  21. ^Moskalyk, R. R. (2003). "Gallium: the backbone of the electronics industry".Minerals Engineering.16(10): 921–929.Bibcode:2003MiEng..16..921M.doi:10.1016/j.mineng.2003.08.003.
  22. ^Cusack, Patricia B.; Courtney, Ronan; Healy, Mark G.; O'Donoghue, Lisa; Ujaczki, Eva (2019). "An evaluation of the general composition and critical raw material content of bauxite residue in a storage area over a twelve-year period".Journal of Cleaner Production.208(20): 393.Bibcode:2019JCPro.208..393C.doi:10.1016/j.jclepro.2018.10.083.hdl:10379/14624– via Elsevier Science Direct.
  23. ^abcdefAnnandale, Mark; Meadows, John; Erskine, Peter (2021). "Indigenous forest livelihoods and bauxite mining: A case-study from northern Australia".Journal of Environmental Management.294:113014.Bibcode:2021JEnvM.29413014A.doi:10.1016/j.jenvman.2021.113014.PMID34144319.
  24. ^abcdefgMorris, Jason (2013).The Vietnamese Bauxite Mining Controversy: the Emergence of a New Oppositional Politics(PhD thesis). University of California, Berkeley – via ProQuest.
  25. ^abcdefgPurwins, Sebastian (2022)."Bauxite mining at Atewa Forest Reserve, Ghana: a political ecology of a conservation-exploitation conflict".GeoJournal.87(2): 1085–1097.doi:10.1007/s10708-020-10303-3.ISSN0343-2521.PMC7512217.PMID32989342.
  26. ^abcdPadel, F. (2015). "The Bauxite-Aluminium Industry and India's Adivasis".Mining, the Aluminium Industry and Indigenous Peoples(PDF).pp. 101–112.

Further reading[edit]

  • Bárdossy, G. (1982):Karst Bauxites: Bauxite deposits on carbonate rocks.Elsevier Sci. Publ. 441 p.
  • Bárdossy, G. and Aleva, G.J.J. (1990):Lateritic Bauxites.Developments in Economic Geology 27, Elsevier Sci. Publ. 624 p.ISBN0-444-98811-4
  • Grant, C.; Lalor, G. and Vutchkov, M. (2005)Comparison of bauxites from Jamaica, the Dominican Republic and Suriname.Journal of Radioanalytical and Nuclear Chemistry p. 385–388 Vol.266, No.3
  • Hanilçi, N. (2013).Geological and geochemical evolution of the Bolkardaği bauxite deposits, Karaman, Turkey: Transformation from shale to bauxite.Journal of Geochemical Exploration

External links[edit]

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