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For the alloys of aluminium, see aluminium alloy. Aluminium_sentence_0

Aluminium (aluminum in American and Canadian English) is a chemical element with the symbol Al and atomic number 13. Aluminium_sentence_1

It is a silvery-white, soft, non-magnetic and ductile metal in the boron group. Aluminium_sentence_2

By mass, aluminium is the most abundant metal in the Earth's crust and the third most abundant element (after oxygen and silicon). Aluminium_sentence_3

The abundance of aluminium decreases relative to other elements at greater depths into Earth's mantle and beyond. Aluminium_sentence_4

The chief ore of aluminium is bauxite. Aluminium_sentence_5

Aluminium metal is highly reactive, so native specimens are rare and limited to extreme reducing environments. Aluminium_sentence_6

Instead, it is found combined in over 270 different minerals. Aluminium_sentence_7

Aluminium is remarkable for its low density and its ability to resist corrosion through the phenomenon of passivation. Aluminium_sentence_8

Aluminium and its alloys are vital to the aerospace industry and important in transportation and building industries, such as building facades and window frames. Aluminium_sentence_9

The oxides and sulfates are the most useful compounds of aluminium. Aluminium_sentence_10

Despite its prevalence in the environment, no living organism is known to use aluminium salts metabolically, but aluminium is well tolerated by plants and animals. Aluminium_sentence_11

Because of these salts' abundance, the potential for a biological role for them is of continuing interest, and studies continue. Aluminium_sentence_12

Physical characteristics Aluminium_section_0

Isotopes Aluminium_section_1

Main article: Isotopes of aluminium Aluminium_sentence_13

Of aluminium isotopes, only Al is stable. Aluminium_sentence_14

This is consistent with aluminium having an odd atomic number. Aluminium_sentence_15

It is the only primordial aluminium isotope, i.e. the only one that has existed on Earth in its current form since the formation of the planet. Aluminium_sentence_16

Nearly all aluminium on Earth is present as this isotope, which makes it a mononuclidic element and means that its standard atomic weight is virtually the same as that of the isotope. Aluminium_sentence_17

The standard atomic weight of aluminium is low in comparison with many other metals, which has consequences for the element's properties (see below). Aluminium_sentence_18

This makes aluminium very useful in nuclear magnetic resonance (NMR), as its single stable isotope has a high NMR sensitivity. Aluminium_sentence_19

All other isotopes of aluminium are radioactive. Aluminium_sentence_20

The most stable of these is Al: while it was present along with stable Al in the interstellar medium from which the Solar System formed, having been produced by stellar nucleosynthesis as well, its half-life is only 717,000 years and therefore a detectable amount has not survived since the formation of the planet. Aluminium_sentence_21

However, minute traces of Al are produced from argon in the atmosphere by spallation caused by cosmic ray protons. Aluminium_sentence_22

The ratio of Al to Be has been used for radiodating of geological processes over 10 to 10 year time scales, in particular transport, deposition, sediment storage, burial times, and erosion. Aluminium_sentence_23

Most meteorite scientists believe that the energy released by the decay of Al was responsible for the melting and differentiation of some asteroids after their formation 4.55 billion years ago. Aluminium_sentence_24

The remaining isotopes of aluminium, with mass numbers ranging from 22 to 43, all have half-lives well under an hour. Aluminium_sentence_25

Three metastable states are known, all with half-lives under a minute. Aluminium_sentence_26

Electron shell Aluminium_section_2

An aluminium atom has 13 electrons, arranged in an electron configuration of Ne 3s 3p, with three electrons beyond a stable noble gas configuration. Aluminium_sentence_27

Accordingly, the combined first three ionization energies of aluminium are far lower than the fourth ionization energy alone. Aluminium_sentence_28

Such an electron configuration is shared with the other well-characterized members of its group, boron, gallium, indium, and thallium; it is also expected for nihonium. Aluminium_sentence_29

Aluminium can relatively easily surrender its three outermost electrons in many chemical reactions (see below). Aluminium_sentence_30

The electronegativity of aluminium is 1.61 (Pauling scale). Aluminium_sentence_31

A free aluminium atom has a radius of 143 pm. Aluminium_sentence_32

With the three outermost electrons removed, the radius shrinks to 39 pm for a 4-coordinated atom or 53.5 pm for a 6-coordinated atom. Aluminium_sentence_33

At standard temperature and pressure, aluminium atoms (when not affected by atoms of other elements) form a face-centered cubic crystal system bound by metallic bonding provided by atoms' outermost electrons; hence aluminium (at these conditions) is a metal. Aluminium_sentence_34

This crystal system is shared by many other metals, such as lead and copper; the size of a unit cell of aluminium is comparable to that of those other metals. Aluminium_sentence_35

It is however not shared by the other members of its group; boron has ionization energies too high to allow metallization, thallium has a hexagonal close-packed structure, and gallium and indium have unusual structures that are not close-packed like those of aluminium and thallium. Aluminium_sentence_36

Since few electrons are available for metallic bonding, aluminium metal is soft with a low melting point and low electrical resistivity, as is common for post-transition metals. Aluminium_sentence_37

Bulk Aluminium_section_3

Aluminium metal has an appearance ranging from silvery white to dull gray, depending on the surface roughness. Aluminium_sentence_38

A fresh film of aluminium serves as a good reflector (approximately 92%) of visible light and an excellent reflector (as much as 98%) of medium and far infrared radiation. Aluminium_sentence_39

The density of aluminium is 2.70 g/cm, about 1/3 that of steel, much lower than other commonly encountered metals, making aluminium parts easily identifiable through their lightness. Aluminium_sentence_40

Aluminium's low density compared to most other metals arises from the fact that its nuclei are much lighter, while difference in the unit cell size does not compensate for this difference. Aluminium_sentence_41

The only lighter metals are the metals of groups 1 and 2, which apart from beryllium and magnesium are too reactive for structural use (and beryllium is very toxic). Aluminium_sentence_42

Aluminium is not as strong or stiff as steel, but the low density makes up for this in the aerospace industry and for many other applications where light weight and relatively high strength are crucial. Aluminium_sentence_43

Pure aluminium is quite soft and lacking in strength. Aluminium_sentence_44

In most applications various aluminium alloys are used instead because of their higher strength and hardness. Aluminium_sentence_45

The yield strength of pure aluminium is 7–11 MPa, while aluminium alloys have yield strengths ranging from 200 MPa to 600 MPa. Aluminium_sentence_46

Aluminium is ductile, with a percent elongation of 50-70%, and malleable allowing it to be easily drawn and extruded. Aluminium_sentence_47

It is also easily machined and cast. Aluminium_sentence_48

Aluminium is an excellent thermal and electrical conductor, having around 60% the conductivity of copper, both thermal and electrical, while having only 30% of copper's density. Aluminium_sentence_49

Aluminium is capable of superconductivity, with a superconducting critical temperature of 1.2 kelvin and a critical magnetic field of about 100 gauss (10 milliteslas). Aluminium_sentence_50

It is paramagnetic and thus essentially unaffected by static magnetic fields. Aluminium_sentence_51

The high electrical conductivity, however, means that it is strongly affected by alternating magnetic fields through the induction of eddy currents. Aluminium_sentence_52

Chemistry Aluminium_section_4

Main article: Compounds of aluminium Aluminium_sentence_53

Aluminium combines characteristics of pre- and post-transition metals. Aluminium_sentence_54

Since it has few available electrons for metallic bonding, like its heavier group 13 congeners, it has the characteristic physical properties of a post-transition metal, with longer-than-expected interatomic distances. Aluminium_sentence_55

Furthermore, as Al is a small and highly charged cation, it is strongly polarizing and bonding in aluminium compounds tends towards covalency; this behaviour is similar to that of beryllium (Be), and the two display an example of a diagonal relationship. Aluminium_sentence_56

The underlying core under aluminium's valence shell is that of the preceding noble gas, whereas those of its heavier congeners gallium and indium, thallium, and nihonium also include a filled d-subshell and in some cases a filled f-subshell. Aluminium_sentence_57

Hence, the inner electrons of aluminium shield the valence electrons almost completely, unlike those of aluminium's heavier congeners. Aluminium_sentence_58

As such, aluminium is the most electropositive metal in its group, and its hydroxide is in fact more basic than that of gallium. Aluminium_sentence_59

Aluminium also bears minor similarities to the metalloid boron in the same group: AlX3 compounds are valence isoelectronic to BX3 compounds (they have the same valence electronic structure), and both behave as Lewis acids and readily form adducts. Aluminium_sentence_60

Additionally, one of the main motifs of boron chemistry is regular icosahedral structures, and aluminium forms an important part of many icosahedral quasicrystal alloys, including the Al–Zn–Mg class. Aluminium_sentence_61

Aluminium has a high chemical affinity to oxygen, which renders it suitable for use as a reducing agent in the thermite reaction. Aluminium_sentence_62

A fine powder of aluminium metal reacts explosively on contact with liquid oxygen; under normal conditions, however, aluminium forms a thin oxide layer (~ 5 nm at room temperature) that protects the metal from further corrosion by oxygen, water, or dilute acid, a process termed passivation. Aluminium_sentence_63

Because of its general resistance to corrosion, aluminium is one of the few metals that retains silvery reflectance in finely powdered form, making it an important component of silver-colored paints. Aluminium_sentence_64

Aluminium is not attacked by oxidizing acids because of its passivation. Aluminium_sentence_65

This allows aluminium to be used to store reagents such as nitric acid, concentrated sulfuric acid, and some organic acids. Aluminium_sentence_66

In hot concentrated hydrochloric acid, aluminium reacts with water with evolution of hydrogen, and in aqueous sodium hydroxide or potassium hydroxide at room temperature to form aluminates—protective passivation under these conditions is negligible. Aluminium_sentence_67

Aqua regia also dissolves aluminium. Aluminium_sentence_68

Aluminium is corroded by dissolved chlorides, such as common sodium chloride, which is why household plumbing is never made from aluminium. Aluminium_sentence_69

The oxide layer on aluminium is also destroyed by contact with mercury due to amalgamation or with salts of some electropositive metals. Aluminium_sentence_70

As such, the strongest aluminium alloys are less corrosion-resistant due to galvanic reactions with alloyed copper, and aluminium's corrosion resistance is greatly reduced by aqueous salts, particularly in the presence of dissimilar metals. Aluminium_sentence_71

Aluminium reacts with most nonmetals upon heating, forming compounds such as aluminium nitride (AlN), aluminium sulfide (Al2S3), and the aluminium halides (AlX3). Aluminium_sentence_72

It also forms a wide range of intermetallic compounds involving metals from every group on the periodic table. Aluminium_sentence_73

Inorganic compounds Aluminium_section_5

The vast majority of compounds, including all aluminium-containing minerals and all commercially significant aluminium compounds, feature aluminium in the oxidation state 3+. Aluminium_sentence_74

The coordination number of such compounds varies, but generally Al is either six- or four-coordinate. Aluminium_sentence_75

Almost all compounds of aluminium(III) are colorless. Aluminium_sentence_76

In aqueous solution, Al exists as the hexaaqua cation [Al(H2O)6], which has an approximate pKa of 10. Aluminium_sentence_77

Such solutions are acidic as this cation can act as a proton donor and progressively hydrolyse until a precipitate of aluminium hydroxide, Al(OH)3, forms. Aluminium_sentence_78

This is useful for clarification of water, as the precipitate nucleates on suspended particles in the water, hence removing them. Aluminium_sentence_79

Increasing the pH even further leads to the hydroxide dissolving again as aluminate, [Al(H2O)2(OH)4], is formed. Aluminium_sentence_80

Aluminium hydroxide forms both salts and aluminates and dissolves in acid and alkali, as well as on fusion with acidic and basic oxides. Aluminium_sentence_81

This behaviour of Al(OH)3 is termed amphoterism, and is characteristic of weakly basic cations that form insoluble hydroxides and whose hydrated species can also donate their protons. Aluminium_sentence_82

One effect of this is that aluminium salts with weak acids are hydrolysed in water to the aquated hydroxide and the corresponding nonmetal hydride: for example, aluminium sulfide yields hydrogen sulfide. Aluminium_sentence_83

However, some salts like aluminium carbonate exist in aqueous solution but are unstable as such; and only incomplete hydrolysis takes place for salts with strong acids, such as the halides, nitrate, and sulfate. Aluminium_sentence_84

For similar reasons, anhydrous aluminium salts cannot be made by heating their "hydrates": hydrated aluminium chloride is in fact not AlCl3·6H2O but [Al(H2O)6]Cl3, and the Al–O bonds are so strong that heating is not sufficient to break them and form Al–Cl bonds instead: Aluminium_sentence_85


  • 2[Al(H2O)6]Cl3 heat→  Al2O3 + 6 HCl + 9 H2OAluminium_item_0_0

All four trihalides are well known. Aluminium_sentence_86

Unlike the structures of the three heavier trihalides, aluminium fluoride (AlF3) features six-coordinate aluminium, which explains its involatility and insolubility as well as high heat of formation. Aluminium_sentence_87

Each aluminium atom is surrounded by six fluorine atoms in a distorted octahedral arrangement, with each fluorine atom being shared between the corners of two octahedra. Aluminium_sentence_88

Such {AlF6} units also exist in complex fluorides such as cryolite, Na3AlF6. Aluminium_sentence_89

AlF3 melts at 1,290 °C (2,354 °F) and is made by reaction of aluminium oxide with hydrogen fluoride gas at 700 °C (1,292 °F). Aluminium_sentence_90

With heavier halides, the coordination numbers are lower. Aluminium_sentence_91

The other trihalides are dimeric or polymeric with tetrahedral four-coordinate aluminium centers. Aluminium_sentence_92

Aluminium trichloride (AlCl3) has a layered polymeric structure below its melting point of 192.4 °C (378 °F) but transforms on melting to Al2Cl6 dimers. Aluminium_sentence_93

At higher temperatures those increasingly dissociate into trigonal planar AlCl3 monomers similar to the structure of BCl3. Aluminium_sentence_94

Aluminium tribromide and aluminium triiodide form Al2X6 dimers in all three phases and hence do not show such significant changes of properties upon phase change. Aluminium_sentence_95

These materials are prepared by treating aluminium metal with the halogen. Aluminium_sentence_96

The aluminium trihalides form many addition compounds or complexes; their Lewis acidic nature makes them useful as catalysts for the Friedel–Crafts reactions. Aluminium_sentence_97

Aluminium trichloride has major industrial uses involving this reaction, such as in the manufacture of anthraquinones and styrene; it is also often used as the precursor for many other aluminium compounds and as a reagent for converting nonmetal fluorides into the corresponding chlorides (a transhalogenation reaction). Aluminium_sentence_98

Aluminium forms one stable oxide with the chemical formula Al2O3, commonly called alumina. Aluminium_sentence_99

It can be found in nature in the mineral corundum, α-alumina; there is also a γ-alumina phase. Aluminium_sentence_100

Its crystalline form, corundum, is very hard (Mohs hardness 9), has a high melting point of 2,045 °C (3,713 °F), has very low volatility, is chemically inert, and a good electrical insulator, it is often used in abrasives (such as toothpaste), as a refractory material, and in ceramics, as well as being the starting material for the electrolytic production of aluminium metal. Aluminium_sentence_101

Sapphire and ruby are impure corundum contaminated with trace amounts of other metals. Aluminium_sentence_102

The two main oxide-hydroxides, AlO(OH), are boehmite and diaspore. Aluminium_sentence_103

There are three main trihydroxides: bayerite, gibbsite, and nordstrandite, which differ in their crystalline structure (polymorphs). Aluminium_sentence_104

Many other intermediate and related structures are also known. Aluminium_sentence_105

Most are produced from ores by a variety of wet processes using acid and base. Aluminium_sentence_106

Heating the hydroxides leads to formation of corundum. Aluminium_sentence_107

These materials are of central importance to the production of aluminium and are themselves extremely useful. Aluminium_sentence_108

Some mixed oxide phases are also very useful, such as spinel (MgAl2O4), Na-β-alumina (NaAl11O17), and tricalcium aluminate (Ca3Al2O6, an important mineral phase in Portland cement). Aluminium_sentence_109

The only stable chalcogenides under normal conditions are aluminium sulfide (Al2S3), selenide (Al2Se3), and telluride (Al2Te3). Aluminium_sentence_110

All three are prepared by direct reaction of their elements at about 1,000 °C (1,832 °F) and quickly hydrolyse completely in water to yield aluminium hydroxide and the respective hydrogen chalcogenide. Aluminium_sentence_111

As aluminium is a small atom relative to these chalcogens, these have four-coordinate tetrahedral aluminium with various polymorphs having structures related to wurtzite, with two-thirds of the possible metal sites occupied either in an orderly (α) or random (β) fashion; the sulfide also has a γ form related to γ-alumina, and an unusual high-temperature hexagonal form where half the aluminium atoms have tetrahedral four-coordination and the other half have trigonal bipyramidal five-coordination. Aluminium_sentence_112

Four pnictidesaluminium nitride (AlN), aluminium phosphide (AlP), aluminium arsenide (AlAs), and aluminium antimonide (AlSb) – are known. Aluminium_sentence_113

They are all III-V semiconductors isoelectronic to silicon and germanium, all of which but AlN have the zinc blende structure. Aluminium_sentence_114

All four can be made by high-temperature (and possibly high-pressure) direct reaction of their component elements. Aluminium_sentence_115

Aluminium alloys well with most other metals (with the exception of most alkali metals and group 13 metals) and over 150 intermetallics with other metals are known. Aluminium_sentence_116

Preparation involves heating fixed metals together in certain proportion, followed by gradual cooling and annealing. Aluminium_sentence_117

Bonding in them is predominantly metallic and the crystal structure primarily depends on efficiency of packing. Aluminium_sentence_118

There are few compounds with lower oxidation states. Aluminium_sentence_119

A few aluminium(I) compounds exist: AlF, AlCl, AlBr, and AlI exist in the gaseous phase when the respective trihalide is heated with aluminium, and at cryogenic temperatures. Aluminium_sentence_120

A stable derivative of aluminium monoiodide is the cyclic adduct formed with triethylamine, Al4I4(NEt3)4. Aluminium_sentence_121

Al2O and Al2S also exist but are very unstable. Aluminium_sentence_122

Very simple aluminium(II) compounds are invoked or observed in the reactions of Al metal with oxidants. Aluminium_sentence_123

For example, aluminium monoxide, AlO, has been detected in the gas phase after explosion and in stellar absorption spectra. Aluminium_sentence_124

More thoroughly investigated are compounds of the formula R4Al2 which contain an Al–Al bond and where R is a large organic ligand. Aluminium_sentence_125

Organoaluminium compounds and related hydrides Aluminium_section_6

Main article: Organoaluminium compound Aluminium_sentence_126

A variety of compounds of empirical formula AlR3 and AlR1.5Cl1.5 exist. Aluminium_sentence_127

The aluminium trialkyls and triaryls are reactive, volatile, and colorless liquids or low-melting solids. Aluminium_sentence_128

They catch fire spontaneously in air and react with water, thus necessitating precautions when handling them. Aluminium_sentence_129

They often form dimers, unlike their boron analogues, but this tendency diminishes for branched-chain alkyls (e.g. Pr, Bu, Me3CCH2); for example, triisobutylaluminium exists as an equilibrium mixture of the monomer and dimer. Aluminium_sentence_130

These dimers, such as trimethylaluminium (Al2Me6), usually feature tetrahedral Al centers formed by dimerization with some alkyl group bridging between both aluminium atoms. Aluminium_sentence_131

They are hard acids and react readily with ligands, forming adducts. Aluminium_sentence_132

In industry, they are mostly used in alkene insertion reactions, as discovered by Karl Ziegler, most importantly in "growth reactions" that form long-chain unbranched primary alkenes and alcohols, and in the low-pressure polymerization of ethene and propene. Aluminium_sentence_133

There are also some heterocyclic and cluster organoaluminium compounds involving Al–N bonds. Aluminium_sentence_134

The industrially most important aluminium hydride is lithium aluminium hydride (LiAlH4), which is used in as a reducing agent in organic chemistry. Aluminium_sentence_135

It can be produced from lithium hydride and aluminium trichloride. Aluminium_sentence_136

The simplest hydride, aluminium hydride or alane, is not as important. Aluminium_sentence_137

It is a polymer with the formula (AlH3)n, in contrast to the corresponding boron hydride that is a dimer with the formula (BH3)2. Aluminium_sentence_138

Natural occurrence Aluminium_section_7

See also: List of countries by bauxite production Aluminium_sentence_139

In space Aluminium_section_8

Aluminium's per-particle abundance in the Solar System is 3.15 ppm (parts per million). Aluminium_sentence_140

It is the twelfth most abundant of all elements and third most abundant among the elements that have odd atomic numbers, after hydrogen and nitrogen. Aluminium_sentence_141

The only stable isotope of aluminium, Al, is the eighteenth most abundant nucleus in the Universe. Aluminium_sentence_142

It is created almost entirely after fusion of carbon in massive stars that will later become Type II supernovas: this fusion creates Mg, which, upon capturing free protons and neutrons becomes aluminium. Aluminium_sentence_143

Some smaller quantities of Al are created in hydrogen burning shells of evolved stars, where Mg can capture free protons. Aluminium_sentence_144

Essentially all aluminium now in existence is Al. Aluminium_sentence_145

Al was present in the early Solar System with abundance of 0.005% relative to Al but its half-life of 728,000 years is too short for any original nuclei to survive; Al is therefore extinct. Aluminium_sentence_146

Unlike for Al, hydrogen burning is the primary source of Al, with the nuclide emerging after a nucleus of Mg catches a free proton. Aluminium_sentence_147

However, the trace quantities of Al that do exist are the most common gamma ray emitter in the interstellar gas; if the original Al were still present, gamma ray maps of the Milky Way would be brighter. Aluminium_sentence_148

On Earth Aluminium_section_9

Overall, the Earth is about 1.59% aluminium by mass (seventh in abundance by mass). Aluminium_sentence_149

Aluminium occurs in greater proportion in the Earth's crust than in the Universe at large, because aluminium easily forms the oxide and becomes bound into rocks and stays in the Earth's crust, while less reactive metals sink to the core. Aluminium_sentence_150

In the Earth's crust, aluminium is the most abundant (8.23% by mass) metallic element and the third most abundant of all elements (after oxygen and silicon). Aluminium_sentence_151

A large number of silicates in the Earth's crust contain aluminium. Aluminium_sentence_152

In contrast, the Earth's mantle is only 2.38% aluminium by mass. Aluminium_sentence_153

Aluminium also occurs in seawater at a concentration of 2 μg/kg. Aluminium_sentence_154

Because of its strong affinity for oxygen, aluminium is almost never found in the elemental state; instead it is found in oxides or silicates. Aluminium_sentence_155

Feldspars, the most common group of minerals in the Earth's crust, are aluminosilicates. Aluminium_sentence_156

Aluminium also occurs in the minerals beryl, cryolite, garnet, spinel, and turquoise. Aluminium_sentence_157

Impurities in Al2O3, such as chromium and iron, yield the gemstones ruby and sapphire, respectively. Aluminium_sentence_158

Native aluminium metal can only be found as a minor phase in low oxygen fugacity environments, such as the interiors of certain volcanoes. Aluminium_sentence_159

Native aluminium has been reported in cold seeps in the northeastern continental slope of the South China Sea. Aluminium_sentence_160

It is possible that these deposits resulted from bacterial reduction of tetrahydroxoaluminate Al(OH)4. Aluminium_sentence_161

Although aluminium is a common and widespread element, not all aluminium minerals are economically viable sources of the metal. Aluminium_sentence_162

Almost all metallic aluminium is produced from the ore bauxite (AlOx(OH)3–2x). Aluminium_sentence_163

Bauxite occurs as a weathering product of low iron and silica bedrock in tropical climatic conditions. Aluminium_sentence_164

In 2017, most bauxite was mined in Australia, China, Guinea, and India. Aluminium_sentence_165

History Aluminium_section_10

Main article: History of aluminium Aluminium_sentence_166

The history of aluminium has been shaped by usage of alum. Aluminium_sentence_167

The first written record of alum, made by Greek historian Herodotus, dates back to the 5th century BCE. Aluminium_sentence_168

The ancients are known to have used alum as a dyeing mordant and for city defense. Aluminium_sentence_169

After the Crusades, alum, an indispensable good in the European fabric industry, was a subject of international commerce; it was imported to Europe from the eastern Mediterranean until the mid-15th century. Aluminium_sentence_170

The nature of alum remained unknown. Aluminium_sentence_171

Around 1530, Swiss physician Paracelsus suggested alum was a salt of an earth of alum. Aluminium_sentence_172

In 1595, German doctor and chemist Andreas Libavius experimentally confirmed this. Aluminium_sentence_173

In 1722, German chemist Friedrich Hoffmann announced his belief that the base of alum was a distinct earth. Aluminium_sentence_174

In 1754, German chemist Andreas Sigismund Marggraf synthesized alumina by boiling clay in sulfuric acid and subsequently adding potash. Aluminium_sentence_175

Attempts to produce aluminium metal date back to 1760. Aluminium_sentence_176

The first successful attempt, however, was completed in 1824 by Danish physicist and chemist Hans Christian Ørsted. Aluminium_sentence_177

He reacted anhydrous aluminium chloride with potassium amalgam, yielding a lump of metal looking similar to tin. Aluminium_sentence_178

He presented his results and demonstrated a sample of the new metal in 1825. Aluminium_sentence_179

In 1827, German chemist Friedrich Wöhler repeated Ørsted's experiments but did not identify any aluminium. Aluminium_sentence_180

(The reason for this inconsistency was only discovered in 1921.) Aluminium_sentence_181

He conducted a similar experiment in the same year by mixing anhydrous aluminium chloride with potassium and produced a powder of aluminium. Aluminium_sentence_182

In 1845, he was able to produce small pieces of the metal and described some physical properties of this metal. Aluminium_sentence_183

For many years thereafter, Wöhler was credited as the discoverer of aluminium. Aluminium_sentence_184

As Wöhler's method could not yield great quantities of aluminium, the metal remained rare; its cost exceeded that of gold. Aluminium_sentence_185

The first industrial production of aluminium was established in 1856 by French chemist Henri Etienne Sainte-Claire Deville and companions. Aluminium_sentence_186

Deville had discovered that aluminium trichloride could be reduced by sodium, which was more convenient and less expensive than potassium, which Wöhler had used. Aluminium_sentence_187

Even then, aluminium was still not of great purity and produced aluminium differed in properties by sample. Aluminium_sentence_188

The first industrial large-scale production method was independently developed in 1886 by French engineer Paul Héroult and American engineer Charles Martin Hall; it is now known as the Hall–Héroult process. Aluminium_sentence_189

The Hall–Héroult process converts alumina into the metal. Aluminium_sentence_190

Austrian chemist Carl Joseph Bayer discovered a way of purifying bauxite to yield alumina, now known as the Bayer process, in 1889. Aluminium_sentence_191

Modern production of the aluminium metal is based on the Bayer and Hall–Héroult processes. Aluminium_sentence_192

Prices of aluminium dropped and aluminium became widely used in jewelry, everyday items, eyeglass frames, optical instruments, tableware, and foil in the 1890s and early 20th century. Aluminium_sentence_193

Aluminium's ability to form hard yet light alloys with other metals provided the metal many uses at the time. Aluminium_sentence_194

During World War I, major governments demanded large shipments of aluminium for light strong airframes. Aluminium_sentence_195

By the mid-20th century, aluminium had become a part of everyday life and an essential component of housewares. Aluminium_sentence_196

During the mid-20th century, aluminium emerged as a civil engineering material, with building applications in both basic construction and interior finish work, and increasingly being used in military engineering, for both airplanes and land armor vehicle engines. Aluminium_sentence_197

Earth's first artificial satellite, launched in 1957, consisted of two separate aluminium semi-spheres joined together and all subsequent space vehicles have used aluminium to some extent. Aluminium_sentence_198

The aluminium can was invented in 1956 and employed as a storage for drinks in 1958. Aluminium_sentence_199

Throughout the 20th century, the production of aluminium rose rapidly: while the world production of aluminium in 1900 was 6,800 metric tons, the annual production first exceeded 100,000 metric tons in 1916; 1,000,000 tons in 1941; 10,000,000 tons in 1971. Aluminium_sentence_200

In the 1970s, the increased demand for aluminium made it an exchange commodity; it entered the London Metal Exchange, the oldest industrial metal exchange in the world, in 1978. Aluminium_sentence_201

The output continued to grow: the annual production of aluminium exceeded 50,000,000 metric tons in 2013. Aluminium_sentence_202

The real price for aluminium declined from $14,000 per metric ton in 1900 to $2,340 in 1948 (in 1998 United States dollars). Aluminium_sentence_203

Extraction and processing costs were lowered over technological progress and the scale of the economies. Aluminium_sentence_204

However, the need to exploit lower-grade poorer quality deposits and the use of fast increasing input costs (above all, energy) increased the net cost of aluminium; the real price began to grow in the 1970s with the rise of energy cost. Aluminium_sentence_205

Production moved from the industrialized countries to countries where production was cheaper. Aluminium_sentence_206

Production costs in the late 20th century changed because of advances in technology, lower energy prices, exchange rates of the United States dollar, and alumina prices. Aluminium_sentence_207

The BRIC countries' combined share in primary production and primary consumption grew substantially in the first decade of the 21st century. Aluminium_sentence_208

China is accumulating an especially large share of world's production thanks to abundance of resources, cheap energy, and governmental stimuli; it also increased its consumption share from 2% in 1972 to 40% in 2010. Aluminium_sentence_209

In the United States, Western Europe, and Japan, most aluminium was consumed in transportation, engineering, construction, and packaging. Aluminium_sentence_210

Etymology Aluminium_section_11

Aluminium is named after alumina, a naturally occurring oxide of aluminium, and the name alumina comes from alum, the mineral from which it was collected. Aluminium_sentence_211

The word alum derives from the Latin word alumen, meaning "bitter salt". Aluminium_sentence_212

The word alumen stems from the Proto-Indo-European root *alu- meaning "bitter" or "beer". Aluminium_sentence_213

Coinage Aluminium_section_12

British chemist Humphry Davy, who performed a number of experiments aimed to isolate the metal, is credited as the person who named the element. Aluminium_sentence_214

The first name proposed for the metal to be isolated from alum was alumium, which Davy suggested in an 1808 article on his electrochemical research, published in Philosophical Transactions of the Royal Society. Aluminium_sentence_215

This suggestion was criticized by contemporary chemists from France, Germany, and Sweden, who insisted the metal should be named for the oxide, alumina, from which it would be isolated. Aluminium_sentence_216

A January 1811 summary of one of Davy's lectures at the Royal Society proposed the name aluminium —this is the earliest known published writing to use either of the modern spellings. Aluminium_sentence_217

However, the following year, Davy published a chemistry textbook in which he settled on the spelling aluminum. Aluminium_sentence_218

Both spellings have coexisted since; however, their usage has split by region: aluminum is in use in the United States and Canada while aluminium is in use elsewhere. Aluminium_sentence_219

Spelling Aluminium_section_13

Davy's spelling aluminum is consistent with the Latin naming of metals, which end in -um, e.g. aurum (gold), argentum (silver), ferrum (iron), naming newly discovered elements by replacing a -a or -ite suffix in the oxide's name with -um: lanthanum was named for its oxide lanthana, magnesium for magnesia, tantalum for tantalite, molybdenum for molybdenite (also known as molybdena), cerium for ceria, and thorium for thoria, respectively. Aluminium_sentence_220

As aluminium's oxide is called alumina, not aluminia, the -ium spelling does not follow this pattern. Aluminium_sentence_221

However, other newly discovered elements of the time had names with a -ium suffix, such as potassium, sodium, calcium, and strontium. Aluminium_sentence_222

In 1812, British scientist Thomas Young wrote an anonymous review of Davy's book, in which he proposed the name aluminium instead of aluminum, which he felt had a "less classical sound". Aluminium_sentence_223

This name did catch on: while the -um spelling was occasionally used in Britain, the American scientific language used -ium from the start. Aluminium_sentence_224

Most scientists used -ium throughout the world in the 19th century; it still remains the standard in many other Latin-based languages where the name has the same origin. Aluminium_sentence_225

In 1828, American lexicographer Noah Webster used exclusively the aluminum spelling in his American Dictionary of the English Language. Aluminium_sentence_226

In the 1830s, the -um spelling started to gain usage in the United States; by the 1860s, it had become the more common spelling there outside science. Aluminium_sentence_227

In 1892, Hall used the -um spelling in his advertising handbill for his new electrolytic method of producing the metal, despite his constant use of the -ium spelling in all the patents he filed between 1886 and 1903. Aluminium_sentence_228

It was subsequently suggested this was a typo rather than intended. Aluminium_sentence_229

By 1890, both spellings had been common in the U.S. overall, the -ium spelling being slightly more common; by 1895, the situation had reversed; by 1900, aluminum had become twice as common as aluminium; during the following decade, the -um spelling dominated American usage. Aluminium_sentence_230

In 1925, the American Chemical Society adopted this spelling. Aluminium_sentence_231

The International Union of Pure and Applied Chemistry (IUPAC) adopted aluminium as the standard international name for the element in 1990. Aluminium_sentence_232

In 1993, they recognized aluminum as an acceptable variant; the most recent 2005 edition of the IUPAC nomenclature of inorganic chemistry acknowledges this spelling as well. Aluminium_sentence_233

IUPAC official publications use the -ium spelling as primary but list both where appropriate. Aluminium_sentence_234

Production and refinement Aluminium_section_14

See also: List of countries by primary aluminium production Aluminium_sentence_235


World's top producers of primary aluminium, 2016Aluminium_table_caption_0
CountryAluminium_header_cell_0_0_0 Output


ChinaAluminium_cell_0_1_0 31,873Aluminium_cell_0_1_1
RussiaAluminium_cell_0_2_0 3,561Aluminium_cell_0_2_1
CanadaAluminium_cell_0_3_0 3,208Aluminium_cell_0_3_1
IndiaAluminium_cell_0_4_0 2,896Aluminium_cell_0_4_1
United Arab EmiratesAluminium_cell_0_5_0 2,471Aluminium_cell_0_5_1
AustraliaAluminium_cell_0_6_0 1,635Aluminium_cell_0_6_1
NorwayAluminium_cell_0_7_0 1,247Aluminium_cell_0_7_1
BahrainAluminium_cell_0_8_0 971Aluminium_cell_0_8_1
Saudi ArabiaAluminium_cell_0_9_0 869Aluminium_cell_0_9_1
United StatesAluminium_cell_0_10_0 818Aluminium_cell_0_10_1
BrazilAluminium_cell_0_11_0 793Aluminium_cell_0_11_1
South AfricaAluminium_cell_0_12_0 701Aluminium_cell_0_12_1
IcelandAluminium_cell_0_13_0 700Aluminium_cell_0_13_1
World totalAluminium_cell_0_14_0 58,800Aluminium_cell_0_14_1

Aluminium production is highly energy-consuming, and so the producers tend to locate smelters in places where electric power is both plentiful and inexpensive. Aluminium_sentence_236

As of 2012, the world's largest smelters of aluminium are located in China, Russia, Bahrain, United Arab Emirates, and South Africa. Aluminium_sentence_237

In 2016, China was the top producer of aluminium with a world share of fifty-five percent; the next largest producing countries were Russia, Canada, India, and the United Arab Emirates. Aluminium_sentence_238

According to the International Resource Panel's Metal Stocks in Society report, the global per capita stock of aluminium in use in society (i.e. in cars, buildings, electronics, etc.) is 80 kg (180 lb). Aluminium_sentence_239

Much of this is in more-developed countries (350–500 kg (770–1,100 lb) per capita) rather than less-developed countries (35 kg (77 lb) per capita). Aluminium_sentence_240

Bayer process Aluminium_section_15

Main article: Bayer process Aluminium_sentence_241

Bauxite is converted to aluminium oxide by the Bayer process. Aluminium_sentence_242

Bauxite is blended for uniform composition and then is ground. Aluminium_sentence_243

The resulting slurry is mixed with a hot solution of sodium hydroxide; the mixture is then treated in a digester vessel at a pressure well above atmospheric, dissolving the aluminium hydroxide in bauxite while converting impurities into relatively insoluble compounds: Aluminium_sentence_244

After this reaction, the slurry is at a temperature above its atmospheric boiling point. Aluminium_sentence_245

It is cooled by removing steam as pressure is reduced. Aluminium_sentence_246

The bauxite residue is separated from the solution and discarded. Aluminium_sentence_247

The solution, free of solids, is seeded with small crystals of aluminium hydroxide; this causes decomposition of the [Al(OH)4] ions to aluminium hydroxide. Aluminium_sentence_248

After about half of aluminium has precipitated, the mixture is sent to classifiers. Aluminium_sentence_249

Small crystals of aluminium hydroxide are collected to serve as seeding agents; coarse particles are converted to aluminium oxide by heating; excess solution is removed by evaporation, (if needed) purified, and recycled. Aluminium_sentence_250

Hall–Héroult process Aluminium_section_16

Main articles: Hall–Héroult process and Aluminium smelting Aluminium_sentence_251

The conversion of alumina to aluminium metal is achieved by the Hall–Héroult process. Aluminium_sentence_252

In this energy-intensive process, a solution of alumina in a molten (950 and 980 °C (1,740 and 1,800 °F)) mixture of cryolite (Na3AlF6) with calcium fluoride is electrolyzed to produce metallic aluminium. Aluminium_sentence_253

The liquid aluminium metal sinks to the bottom of the solution and is tapped off, and usually cast into large blocks called aluminium billets for further processing. Aluminium_sentence_254

Anodes of the electrolysis cell are made of carbon—the most resistant material against fluoride corrosion—and either bake at the process or are prebaked. Aluminium_sentence_255

The former, also called Söderberg anodes, are less power-efficient and fumes released during baking are costly to collect, which is why they are being replaced by prebaked anodes even though they save the power, energy, and labor to prebake the cathodes. Aluminium_sentence_256

Carbon for anodes should be preferably pure so that neither aluminium nor the electrolyte is contaminated with ash. Aluminium_sentence_257

Despite carbon's resistivity against corrosion, it is still consumed at a rate of 0.4–0.5 kg per each kilogram of produced aluminium. Aluminium_sentence_258

Cathodes are made of ; high purity for them is not required because impurities leach only very slowly. Aluminium_sentence_259

Cathode is consumed at a rate of 0.02–0.04 kg per each kilogram of produced aluminium. Aluminium_sentence_260

A cell is usually a terminated after 2–6 years following a failure of the cathode. Aluminium_sentence_261

The Hall–Heroult process produces aluminium with a purity of above 99%. Aluminium_sentence_262

Further purification can be done by the Hoopes process. Aluminium_sentence_263

This process involves the electrolysis of molten aluminium with a sodium, barium, and aluminium fluoride electrolyte. Aluminium_sentence_264

The resulting aluminium has a purity of 99.99%. Aluminium_sentence_265

Electric power represents about 20 to 40% of the cost of producing aluminium, depending on the location of the smelter. Aluminium_sentence_266

Aluminium production consumes roughly 5% of electricity generated in the United States. Aluminium_sentence_267

Because of this, alternatives to the Hall–Héroult process have been researched, but none has turned out to be economically feasible. Aluminium_sentence_268

Recycling Aluminium_section_17

Main article: Aluminium recycling Aluminium_sentence_269

Recovery of the metal through recycling has become an important task of the aluminium industry. Aluminium_sentence_270

Recycling was a low-profile activity until the late 1960s, when the growing use of aluminium beverage cans brought it to public awareness. Aluminium_sentence_271

Recycling involves melting the scrap, a process that requires only 5% of the energy used to produce aluminium from ore, though a significant part (up to 15% of the input material) is lost as dross (ash-like oxide). Aluminium_sentence_272

An aluminium stack melter produces significantly less dross, with values reported below 1%. Aluminium_sentence_273

White dross from primary aluminium production and from secondary recycling operations still contains useful quantities of aluminium that can be extracted industrially. Aluminium_sentence_274

The process produces aluminium billets, together with a highly complex waste material. Aluminium_sentence_275

This waste is difficult to manage. Aluminium_sentence_276

It reacts with water, releasing a mixture of gases (including, among others, hydrogen, acetylene, and ammonia), which spontaneously ignites on contact with air; contact with damp air results in the release of copious quantities of ammonia gas. Aluminium_sentence_277

Despite these difficulties, the waste is used as a filler in asphalt and concrete. Aluminium_sentence_278

Applications Aluminium_section_18

Metal Aluminium_section_19

See also: Aluminium alloy Aluminium_sentence_279

The global production of aluminium in 2016 was 58.8 million metric tons. Aluminium_sentence_280

It exceeded that of any other metal except iron (1,231 million metric tons). Aluminium_sentence_281

Aluminium is almost always alloyed, which markedly improves its mechanical properties, especially when tempered. Aluminium_sentence_282

For example, the common aluminium foils and beverage cans are alloys of 92% to 99% aluminium. Aluminium_sentence_283

The main alloying agents are copper, zinc, magnesium, manganese, and silicon (e.g., duralumin) with the levels of other metals in a few percent by weight. Aluminium_sentence_284

The major uses for aluminium metal are in: Aluminium_sentence_285


  • Transportation (automobiles, aircraft, trucks, railway cars, marine vessels, bicycles, spacecraft, etc.). Aluminium is used because of its low density;Aluminium_item_1_1
  • Packaging (cans, foil, frame etc.). Aluminium is used because it is non-toxic, non-adsorptive, and splinter-proof;Aluminium_item_1_2
  • Building and construction (windows, doors, siding, building wire, sheathing, roofing, etc.). Since steel is cheaper, aluminium is used when lightness, corrosion resistance, or engineering features are important;Aluminium_item_1_3
  • Electricity-related uses (conductor alloys, motors and generators, transformers, capacitors, etc.). Aluminium is used because it is relatively cheap, highly conductive, has adequate mechanical strength and low density, and resists corrosion;Aluminium_item_1_4
  • A wide range of household items, from cooking utensils to furniture. Low density, good appearance, ease of fabrication, and durability are the key factors of aluminium usage;Aluminium_item_1_5
  • Machinery and equipment (processing equipment, pipes, tools). Aluminium is used because of its corrosion resistance, non-pyrophoricity, and mechanical strength.Aluminium_item_1_6

Compounds Aluminium_section_20

The great majority (about 90%) of aluminium oxide is converted to metallic aluminium. Aluminium_sentence_286

Being a very hard material (Mohs hardness 9), alumina is widely used as an abrasive; being extraordinarily chemically inert, it is useful in highly reactive environments such as high pressure sodium lamps. Aluminium_sentence_287

Aluminium oxide is commonly used as a catalyst for industrial processes; e.g. the Claus process to convert hydrogen sulfide to sulfur in refineries and to alkylate amines. Aluminium_sentence_288

Many industrial catalysts are supported by alumina, meaning that the expensive catalyst material is dispersed over a surface of the inert alumina. Aluminium_sentence_289

Another principal use is as a drying agent or absorbent. Aluminium_sentence_290

Several sulfates of aluminium have industrial and commercial application. Aluminium_sentence_291

Aluminium sulfate (in its hydrate form) is produced on the annual scale of several millions of metric tons. Aluminium_sentence_292

About two-thirds is consumed in water treatment. Aluminium_sentence_293

The next major application is in the manufacture of paper. Aluminium_sentence_294

It is also used as a mordant in dyeing, in pickling seeds, deodorizing of mineral oils, in leather tanning, and in production of other aluminium compounds. Aluminium_sentence_295

Two kinds of alum, ammonium alum and potassium alum, were formerly used as mordants and in leather tanning, but their use has significantly declined following availability of high-purity aluminium sulfate. Aluminium_sentence_296

Anhydrous aluminium chloride is used as a catalyst in chemical and petrochemical industries, the dyeing industry, and in synthesis of various inorganic and organic compounds. Aluminium_sentence_297

Aluminium hydroxychlorides are used in purifying water, in the paper industry, and as antiperspirants. Aluminium_sentence_298

Sodium aluminate is used in treating water and as an accelerator of solidification of cement. Aluminium_sentence_299

Many aluminium compounds have niche applications, for example: Aluminium_sentence_300


Biology Aluminium_section_21

Despite its widespread occurrence in the Earth's crust, aluminium has no known function in biology. Aluminium_sentence_301

At pH 6–9 (relevant for most natural waters), aluminium precipitates out of water as the hydroxide and is hence not available; most elements behaving this way have no biological role or are toxic. Aluminium_sentence_302

Aluminium salts are remarkably nontoxic, aluminium sulfate having an LD50 of 6207 mg/kg (oral, mouse), which corresponds to 435 grams for an 70 kg (150 lb) person. Aluminium_sentence_303

Toxicity Aluminium_section_22

In most people, aluminium is not as toxic as heavy metals. Aluminium_sentence_304

Aluminium is classified as a non-carcinogen by the United States Department of Health and Human Services. Aluminium_sentence_305

There is little evidence that normal exposure to aluminium presents a risk to healthy adult, and there is evidence of no toxicity if it is consumed in amounts not greater than 40 mg/day per kg of body mass. Aluminium_sentence_306

Most aluminium consumed will leave the body in feces; most of the small part of it that enters the bloodstream, will be excreted via urine. Aluminium_sentence_307

Effects Aluminium_section_23

Aluminium, although rarely, can cause vitamin D-resistant osteomalacia, erythropoietin-resistant microcytic anemia, and central nervous system alterations. Aluminium_sentence_308

People with kidney insufficiency are especially at a risk. Aluminium_sentence_309

Chronic ingestion of hydrated aluminium silicates (for excess gastric acidity control) may result in aluminium binding to intestinal contents and increased elimination of other metals, such as iron or zinc; sufficiently high doses (>50 g/day) can cause anemia. Aluminium_sentence_310

During the 1988 Camelford water pollution incident people in Camelford had their drinking water contaminated with aluminium sulfate for several weeks. Aluminium_sentence_311

A final report into the incident in 2013 concluded it was unlikely that this had caused long-term health problems. Aluminium_sentence_312

Aluminium has been suspected of being a possible cause of Alzheimer's disease, but research into this for over 40 years has found, as of 2018, no good evidence of causal effect. Aluminium_sentence_313

Aluminium increases estrogen-related gene expression in human breast cancer cells cultured in the laboratory. Aluminium_sentence_314

In very high doses, aluminium is associated with altered function of the blood–brain barrier. Aluminium_sentence_315

A small percentage of people have contact allergies to aluminium and experience itchy red rashes, headache, muscle pain, joint pain, poor memory, insomnia, depression, asthma, irritable bowel syndrome, or other symptoms upon contact with products containing aluminium. Aluminium_sentence_316

Exposure to powdered aluminium or aluminium welding fumes can cause pulmonary fibrosis. Aluminium_sentence_317

Fine aluminium powder can ignite or explode, posing another workplace hazard. Aluminium_sentence_318

Exposure routes Aluminium_section_24

Food is the main source of aluminium. Aluminium_sentence_319

Drinking water contains more aluminium than solid food; however, aluminium in food may be absorbed more than aluminium from water. Aluminium_sentence_320

Major sources of human oral exposure to aluminium include food (due to its use in food additives, food and beverage packaging, and cooking utensils), drinking water (due to its use in municipal water treatment), and aluminium-containing medications (particularly antacid/antiulcer and buffered aspirin formulations). Aluminium_sentence_321

Dietary exposure in Europeans averages to 0.2–1.5 mg/kg/week but can be as high as 2.3 mg/kg/week. Aluminium_sentence_322

Higher exposure levels of aluminium are mostly limited to miners, aluminium production workers, and dialysis patients. Aluminium_sentence_323

Consumption of antacids, antiperspirants, vaccines, and cosmetics provide possible routes of exposure. Aluminium_sentence_324

Consumption of acidic foods or liquids with aluminium enhances aluminium absorption, and maltol has been shown to increase the accumulation of aluminium in nerve and bone tissues. Aluminium_sentence_325

Treatment Aluminium_section_25

In case of suspected sudden intake of a large amount of aluminium, the only treatment is deferoxamine mesylate which may be given to help eliminate aluminium from the body by chelation. Aluminium_sentence_326

However, this should be applied with caution as this reduces not only aluminium body levels, but also those of other metals such as copper or iron. Aluminium_sentence_327

Environmental effects Aluminium_section_26

High levels of aluminium occur near mining sites; small amounts of aluminium are released to the environment at the coal-fired power plants or incinerators. Aluminium_sentence_328

Aluminium in the air is washed out by the rain or normally settles down but small particles of aluminium remain in the air for a long time. Aluminium_sentence_329

Acidic precipitation is the main natural factor to mobilize aluminium from natural sources and the main reason for the environmental effects of aluminium; however, the main factor of presence of aluminium in salt and freshwater are the industrial processes that also release aluminium into air. Aluminium_sentence_330

In water, aluminium acts as a toxiс agent on gill-breathing animals such as fish by causing loss of plasma- and hemolymph ions leading to osmoregulatory failure. Aluminium_sentence_331

Organic complexes of aluminium may be easily absorbed and interfere with metabolism in mammals and birds, even though this rarely happens in practice. Aluminium_sentence_332

Aluminium is primary among the factors that reduce plant growth on acidic soils. Aluminium_sentence_333

Although it is generally harmless to plant growth in pH-neutral soils, in acid soils the concentration of toxic Al cations increases and disturbs root growth and function. Aluminium_sentence_334

Wheat has developed a tolerance to aluminium, releasing organic compounds that bind to harmful aluminium cations. Aluminium_sentence_335

Sorghum is believed to have the same tolerance mechanism. Aluminium_sentence_336

Aluminium production possesses its own challenges to the environment on each step of the production process. Aluminium_sentence_337

The major challenge is the greenhouse gas emissions. Aluminium_sentence_338

These gases result from electrical consumption of the smelters and the byproducts of processing. Aluminium_sentence_339

The most potent of these gases are perfluorocarbons from the smelting process. Aluminium_sentence_340

Released sulfur dioxide is one of the primary precursors of acid rain. Aluminium_sentence_341

A Spanish scientific report from 2001 claimed that the fungus Geotrichum candidum consumes the aluminium in compact discs. Aluminium_sentence_342

Other reports all refer back to that report and there is no supporting original research. Aluminium_sentence_343

Better documented, the bacterium Pseudomonas aeruginosa and the fungus Cladosporium resinae are commonly detected in aircraft fuel tanks that use kerosene-based fuels (not avgas), and laboratory cultures can degrade aluminium. Aluminium_sentence_344

However, these life forms do not directly attack or consume the aluminium; rather, the metal is corroded by microbe waste products. Aluminium_sentence_345

See also Aluminium_section_27


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