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18,900 | Rudolph Pintner proposed a set of classification terms in his 1923 book "Intelligence Testing: Methods and Results". Pintner commented that psychologists of his era, including Terman, went about "the measurement of an individual's general ability without waiting for an adequate psychological definition." Pintner retain... | https://en.wikipedia.org/wiki?curid=12940960 |
18,901 | Albert Julius Levine and Louis Marks proposed a broader set of categories in their 1928 book "Testing Intelligence and Achievement". Some of the entries came from contemporary terms for people with intellectual disability. | https://en.wikipedia.org/wiki?curid=12940960 |
18,902 | The second revision (1937) of the Stanford–Binet test retained "quotient IQ" scoring, despite earlier criticism of that method of reporting IQ test standard scores. The term "genius" was no longer used for any IQ score range. The second revision was normed only on children and adolescents (no adults), and only "America... | https://en.wikipedia.org/wiki?curid=12940960 |
18,903 | A data table published later as part of the manual for the 1960 Third Revision (Form L-M) of the Stanford–Binet test reported score distributions from the 1937 second revision standardization group. | https://en.wikipedia.org/wiki?curid=12940960 |
18,904 | David Wechsler, developer of the Wechsler–Bellevue Scale of 1939 (which was later developed into the Wechsler Adult Intelligence Scale) popularized the use of "deviation IQs" as standard scores of IQ tests rather than the "quotient IQs" ("mental age" divided by "chronological age") then used for the Stanford–Binet test... | https://en.wikipedia.org/wiki?curid=12940960 |
18,905 | In 1958, Wechsler published another edition of his book "Measurement and Appraisal of Adult Intelligence". He revised his chapter on the topic of IQ classification and commented that "mental age" scores were not a more valid way to score intelligence tests than IQ scores. He continued to use the same classification ter... | https://en.wikipedia.org/wiki?curid=12940960 |
18,906 | The third revision (Form L-M) in 1960 of the Stanford–Binet IQ test used the deviation scoring pioneered by David Wechsler. For rough comparability of scores between the second and third revision of the Stanford–Binet test, scoring table author Samuel Pinneau set 100 for the median standard score level and 16 standard ... | https://en.wikipedia.org/wiki?curid=12940960 |
18,907 | The first edition of the Woodcock–Johnson Tests of Cognitive Abilities was published by Riverside in 1977. The classifications used by the WJ-R Cog were "modern in that they describe levels of performance as opposed to offering a diagnosis." | https://en.wikipedia.org/wiki?curid=12940960 |
18,908 | The revised version of the Wechsler Adult Intelligence Scale (the WAIS-R) was developed by David Wechsler and published by Psychological Corporation in 1981. Wechsler changed a few of the boundaries for classification categories and a few of their names compared to the 1958 version of the test. The test's manual includ... | https://en.wikipedia.org/wiki?curid=12940960 |
18,909 | The Kaufman Assessment Battery for Children (K-ABC) was developed by Alan S. Kaufman and Nadeen L. Kaufman and published in 1983 by American Guidance Service. | https://en.wikipedia.org/wiki?curid=12940960 |
18,910 | The fourth revision of the Stanford–Binet scales (S-B IV) was developed by Thorndike, Hagen, and Sattler and published by Riverside Publishing in 1986. It retained the deviation scoring of the third revision with each standard deviation from the median being defined as a 16 IQ point difference. The S-B IV adopted new c... | https://en.wikipedia.org/wiki?curid=12940960 |
18,911 | The third edition of the Wechsler Adult Intelligence Scale (WAIS-III) used different classification terminology from the earliest versions of Wechsler tests. | https://en.wikipedia.org/wiki?curid=12940960 |
18,912 | The earliest terms for classifying individuals of low intelligence were medical or legal terms that preceded the development of IQ testing. The legal system recognized a concept of some individuals being so cognitively impaired that they were not responsible for criminal behavior. Medical doctors sometimes encountered ... | https://en.wikipedia.org/wiki?curid=12940960 |
18,913 | In current medical diagnosis, IQ scores alone are not conclusive for a finding of intellectual disability. Recently adopted diagnostic standards place the major emphasis on the adaptive behavior of each individual, with IQ score just being one factor in diagnosis in addition to adaptive behavior scales, and no category... | https://en.wikipedia.org/wiki?curid=12940960 |
18,914 | In the United States, the Supreme Court ruled in the case "Atkins v. Virginia", 536 U.S. 304 (2002) that states could not impose capital punishment on persons with "mental retardation", defined in subsequent cases as persons with IQ scores below 70. This legal standard continues to be actively litigated in capital case... | https://en.wikipedia.org/wiki?curid=12940960 |
18,915 | Historically, terms for intellectual disability eventually become perceived as an insult, in a process commonly known as the euphemism treadmill. The terms "mental retardation" and "mentally retarded" became popular in the middle of the 20th century to replace the previous set of terms, which included "imbecile", "idio... | https://en.wikipedia.org/wiki?curid=12940960 |
18,916 | The American Association for the Study of the Feeble-minded divided adults with intellectual deficits into three categories. "Idiot" indicated the greatest degree of intellectual disability in which a person's mental age is below three years. "Imbecile" indicated an intellectual disability less severe than idiocy and a... | https://en.wikipedia.org/wiki?curid=12940960 |
18,917 | The term "cretin" dates to 1770–80 and comes from a dialectal French word for Christian. The implication was that people with significant intellectual or developmental disabilities were "still human" (or "still Christian") and deserved to be treated with basic human dignity. Although "cretin" is no longer in use, the t... | https://en.wikipedia.org/wiki?curid=12940960 |
18,918 | "Mongolism" and "Mongoloid idiot" were terms used to identify someone with Down syndrome, as the doctor who first described the syndrome, John Langdon Down, believed that children with Down syndrome shared facial similarities with the now-obsolete category of "Mongolian race". The Mongolian People's Republic requested ... | https://en.wikipedia.org/wiki?curid=12940960 |
18,919 | "Retarded" comes from the Latin "retardare", "to make slow, delay, keep back, or hinder", so "mental retardation" meant the same as "mentally delayed". The first record of retarded in relation to being mentally slow was in 1895. The term "mentally retarded" was used to replace terms like "idiot", "moron", and "imbecile... | https://en.wikipedia.org/wiki?curid=12940960 |
18,920 | Francis Galton (1822–1911) was a pioneer in investigating both eminent human achievement and mental testing. In his book "Hereditary Genius", writing before the development of IQ testing, he proposed that hereditary influences on eminent achievement are strong, and that eminence is rare in the general population. Lewis... | https://en.wikipedia.org/wiki?curid=12940960 |
18,921 | The Terman longitudinal study in California eventually provided historical evidence on how genius is related to IQ scores. Many California pupils were recommended for the study by schoolteachers. Two pupils who were tested but rejected for inclusion in the study because of IQ scores too low for the study grew up to be ... | https://en.wikipedia.org/wiki?curid=12940960 |
18,922 | A major point of consensus among all scholars of intellectual giftedness is that there is no generally agreed upon definition of giftedness. Although there is no scholarly agreement about identifying gifted learners, there is a de facto reliance on IQ scores for identifying participants in school gifted education progr... | https://en.wikipedia.org/wiki?curid=12940960 |
18,923 | Five levels of giftedness have been suggested to differentiate the vast difference in abilities that exists between children on varying ends of the gifted spectrum. Although there is no strong consensus on the validity of these quantifiers, they are accepted by many experts of gifted children. | https://en.wikipedia.org/wiki?curid=12940960 |
18,924 | As long ago as 1937, Lewis Terman pointed out that error of estimation in IQ scoring increases as IQ score increases, so that there is less and less certainty about assigning a test-taker to one band of scores or another as one looks at higher bands. Current IQ tests also have large error bands for high IQ scores. As a... | https://en.wikipedia.org/wiki?curid=12940960 |
18,925 | Aluminium (aluminum in American and Canadian English) is a chemical element with the symbol Al and atomic number 13. Aluminium has a density lower than those of other common metals, at approximately one third that of steel. It has a great affinity towards oxygen, and forms a protective layer of oxide on the surface whe... | https://en.wikipedia.org/wiki?curid=904 |
18,926 | Chemically, aluminium is a post-transition metal in the boron group; as is common for the group, aluminium forms compounds primarily in the +3 oxidation state. The aluminium cation Al is small and highly charged; as such, it is polarizing, and bonds aluminium forms tend towards covalency. The strong affinity towards ox... | https://en.wikipedia.org/wiki?curid=904 |
18,927 | The discovery of aluminium was announced in 1825 by Danish physicist Hans Christian Ørsted. The first industrial production of aluminium was initiated by French chemist Henri Étienne Sainte-Claire Deville in 1856. Aluminium became much more available to the public with the Hall–Héroult process developed independently b... | https://en.wikipedia.org/wiki?curid=904 |
18,928 | 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. Because of the abundance of these salts, the potential for a biological role for them is of interest, and studies continue. | https://en.wikipedia.org/wiki?curid=904 |
18,929 | Of aluminium isotopes, only is stable. This situation is common for elements with an odd atomic number. 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. Nearly all aluminium on Earth is present as this isotope, which makes it... | https://en.wikipedia.org/wiki?curid=904 |
18,930 | All other isotopes of aluminium are radioactive. 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... | https://en.wikipedia.org/wiki?curid=904 |
18,931 | The remaining isotopes of aluminium, with mass numbers ranging from 22 to 43, all have half-lives well under an hour. Three metastable states are known, all with half-lives under a minute. | https://en.wikipedia.org/wiki?curid=904 |
18,932 | An aluminium atom has 13 electrons, arranged in an electron configuration of , with three electrons beyond a stable noble gas configuration. Accordingly, the combined first three ionization energies of aluminium are far lower than the fourth ionization energy alone. Such an electron configuration is shared with the oth... | https://en.wikipedia.org/wiki?curid=904 |
18,933 | A free aluminium atom has a radius of 143 pm. 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. At standard temperature and pressure, aluminium atoms (when not affected by atoms of other elements) form a face-centered cubic crystal syst... | https://en.wikipedia.org/wiki?curid=904 |
18,934 | Aluminium metal has an appearance ranging from silvery white to dull gray, depending on the surface roughness. Aluminium mirrors are the most reflective of all metal mirrors for the near ultraviolet and far infrared light, and one of the most reflective in the visible spectrum, nearly on par with silver, and the two th... | https://en.wikipedia.org/wiki?curid=904 |
18,935 | 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's low density compared to most other metals arises from the fact that its nuclei are much lighter, while difference in the unit... | https://en.wikipedia.org/wiki?curid=904 |
18,936 | Pure aluminium is quite soft and lacking in strength. In most applications various aluminium alloys are used instead because of their higher strength and hardness. The yield strength of pure aluminium is 7–11 MPa, while aluminium alloys have yield strengths ranging from 200 MPa to 600 MPa. Aluminium is ductile, with a ... | https://en.wikipedia.org/wiki?curid=904 |
18,937 | 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 is capable of superconductivity, with a superconducting critical temperature of 1.2 kelvin and a critical magnetic field of about 10... | https://en.wikipedia.org/wiki?curid=904 |
18,938 | Aluminium combines characteristics of pre- and post-transition metals. 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. Furthermore, as Al is a small ... | https://en.wikipedia.org/wiki?curid=904 |
18,939 | The underlying core under aluminium's valence shell is that of the preceding noble gas, whereas those of its heavier congeners gallium, indium, thallium, and nihonium also include a filled d-subshell and in some cases a filled f-subshell. Hence, the inner electrons of aluminium shield the valence electrons almost compl... | https://en.wikipedia.org/wiki?curid=904 |
18,940 | Aluminium has a high chemical affinity to oxygen, which renders it suitable for use as a reducing agent in the thermite reaction. 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 prote... | https://en.wikipedia.org/wiki?curid=904 |
18,941 | 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. Aqua regia also dissolves aluminium. Aluminium is corroded by dissolve... | https://en.wikipedia.org/wiki?curid=904 |
18,942 | Aluminium reacts with most nonmetals upon heating, forming compounds such as aluminium nitride (AlN), aluminium sulfide (AlS), and the aluminium halides (AlX). It also forms a wide range of intermetallic compounds involving metals from every group on the periodic table. | https://en.wikipedia.org/wiki?curid=904 |
18,943 | The vast majority of compounds, including all aluminium-containing minerals and all commercially significant aluminium compounds, feature aluminium in the oxidation state 3+. The coordination number of such compounds varies, but generally Al is either six- or four-coordinate. Almost all compounds of aluminium(III) are ... | https://en.wikipedia.org/wiki?curid=904 |
18,944 | In aqueous solution, Al exists as the hexaaqua cation [Al(HO)], which has an approximate K of 10. Such solutions are acidic as this cation can act as a proton donor and progressively hydrolyze until a precipitate of aluminium hydroxide, Al(OH), forms. This is useful for clarification of water, as the precipitate nuclea... | https://en.wikipedia.org/wiki?curid=904 |
18,945 | Aluminium hydroxide forms both salts and aluminates and dissolves in acid and alkali, as well as on fusion with acidic and basic oxides. This behavior of Al(OH) is termed amphoterism and is characteristic of weakly basic cations that form insoluble hydroxides and whose hydrated species can also donate their protons. On... | https://en.wikipedia.org/wiki?curid=904 |
18,946 | All four trihalides are well known. Unlike the structures of the three heavier trihalides, aluminium fluoride (AlF) features six-coordinate aluminium, which explains its involatility and insolubility as well as high heat of formation. Each aluminium atom is surrounded by six fluorine atoms in a distorted octahedral arr... | https://en.wikipedia.org/wiki?curid=904 |
18,947 | With heavier halides, the coordination numbers are lower. The other trihalides are dimeric or polymeric with tetrahedral four-coordinate aluminium centers. Aluminium trichloride (AlCl) has a layered polymeric structure below its melting point of but transforms on melting to AlCl dimers. At higher temperatures those inc... | https://en.wikipedia.org/wiki?curid=904 |
18,948 | Aluminium forms one stable oxide with the chemical formula AlO, commonly called alumina. It can be found in nature in the mineral corundum, α-alumina; there is also a γ-alumina phase. Its crystalline form, corundum, is very hard (Mohs hardness 9), has a high melting point of , has very low volatility, is chemically ine... | https://en.wikipedia.org/wiki?curid=904 |
18,949 | The only stable chalcogenides under normal conditions are aluminium sulfide (AlS), selenide (AlSe), and telluride (AlTe). All three are prepared by direct reaction of their elements at about and quickly hydrolyze completely in water to yield aluminium hydroxide and the respective hydrogen chalcogenide. As aluminium is ... | https://en.wikipedia.org/wiki?curid=904 |
18,950 | Four pnictides – aluminium nitride (AlN), aluminium phosphide (AlP), aluminium arsenide (AlAs), and aluminium antimonide (AlSb) – are known. They are all III-V semiconductors isoelectronic to silicon and germanium, all of which but AlN have the zinc blende structure. All four can be made by high-temperature (and possib... | https://en.wikipedia.org/wiki?curid=904 |
18,951 | 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. Preparation involves heating fixed metals together in certain proportion, followed by gradual cooling and annealing. Bonding in them is predominantly metal... | https://en.wikipedia.org/wiki?curid=904 |
18,952 | There are few compounds with lower oxidation states. 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. A stable derivative of aluminium monoiodide is the cyclic adduct formed with triethylamine, ... | https://en.wikipedia.org/wiki?curid=904 |
18,953 | A variety of compounds of empirical formula AlR and AlRCl exist. The aluminium trialkyls and triaryls are reactive, volatile, and colorless liquids or low-melting solids. They catch fire spontaneously in air and react with water, thus necessitating precautions when handling them. They often form dimers, unlike their bo... | https://en.wikipedia.org/wiki?curid=904 |
18,954 | The industrially most important aluminium hydride is lithium aluminium hydride (LiAlH), which is used in as a reducing agent in organic chemistry. It can be produced from lithium hydride and aluminium trichloride. The simplest hydride, aluminium hydride or alane, is not as important. It is a polymer with the formula (A... | https://en.wikipedia.org/wiki?curid=904 |
18,955 | Aluminium's per-particle abundance in the Solar System is 3.15 ppm (parts per million). 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. The only stable isotope of aluminium, Al, is the eighteenth most abundant nucleus ... | https://en.wikipedia.org/wiki?curid=904 |
18,956 | Overall, the Earth is about 1.59% aluminium by mass (seventh in abundance by mass). 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... | https://en.wikipedia.org/wiki?curid=904 |
18,957 | Because of its strong affinity for oxygen, aluminium is almost never found in the elemental state; instead it is found in oxides or silicates. Feldspars, the most common group of minerals in the Earth's crust, are aluminosilicates. Aluminium also occurs in the minerals beryl, cryolite, garnet, spinel, and turquoise. Im... | https://en.wikipedia.org/wiki?curid=904 |
18,958 | Although aluminium is a common and widespread element, not all aluminium minerals are economically viable sources of the metal. Almost all metallic aluminium is produced from the ore bauxite (AlO(OH)). Bauxite occurs as a weathering product of low iron and silica bedrock in tropical climatic conditions. In 2017, most b... | https://en.wikipedia.org/wiki?curid=904 |
18,959 | The history of aluminium has been shaped by usage of alum. The first written record of alum, made by Greek historian Herodotus, dates back to the 5th century BCE. The ancients are known to have used alum as a dyeing mordant and for city defense. After the Crusades, alum, an indispensable good in the European fabric ind... | https://en.wikipedia.org/wiki?curid=904 |
18,960 | The nature of alum remained unknown. Around 1530, Swiss physician Paracelsus suggested alum was a salt of an earth of alum. In 1595, German doctor and chemist Andreas Libavius experimentally confirmed this. In 1722, German chemist Friedrich Hoffmann announced his belief that the base of alum was a distinct earth. In 17... | https://en.wikipedia.org/wiki?curid=904 |
18,961 | Attempts to produce aluminium metal date back to 1760. The first successful attempt, however, was completed in 1824 by Danish physicist and chemist Hans Christian Ørsted. He reacted anhydrous aluminium chloride with potassium amalgam, yielding a lump of metal looking similar to tin. He presented his results and demonst... | https://en.wikipedia.org/wiki?curid=904 |
18,962 | As Wöhler's method could not yield great quantities of aluminium, the metal remained rare; its cost exceeded that of gold. The first industrial production of aluminium was established in 1856 by French chemist Henri Etienne Sainte-Claire Deville and companions. Deville had discovered that aluminium trichloride could be... | https://en.wikipedia.org/wiki?curid=904 |
18,963 | 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. The Hall–Héroult process converts alumina into metal. Austrian chemist Carl Joseph Bayer discovered a way of puri... | https://en.wikipedia.org/wiki?curid=904 |
18,964 | 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's ability to form hard yet light alloys with other metals provided the metal with many uses at the time. During World War I, m... | https://en.wikipedia.org/wiki?curid=904 |
18,965 | By the mid-20th century, aluminium had become a part of everyday life and an essential component of housewares. In 1954, production of aluminium surpassed that of copper, historically second in production only to iron, making it the most produced non-ferrous metal. During the mid-20th century, aluminium emerged as a ci... | https://en.wikipedia.org/wiki?curid=904 |
18,966 | 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. In the 1970s, the increased demand for aluminium made it an exc... | https://en.wikipedia.org/wiki?curid=904 |
18,967 | The real price for aluminium declined from $14,000 per metric ton in 1900 to $2,340 in 1948 (in 1998 United States dollars). Extraction and processing costs were lowered over technological progress and the scale of the economies. However, the need to exploit lower-grade poorer quality deposits and the use of fast incre... | https://en.wikipedia.org/wiki?curid=904 |
18,968 | The names "aluminium" and "aluminum" are derived from the word "alumine", an obsolete term for "alumina", a naturally occurring oxide of aluminium. "Alumine" was borrowed from French, which in turn derived it from "alumen", the classical Latin name for alum, the mineral from which it was collected. The Latin word "alum... | https://en.wikipedia.org/wiki?curid=904 |
18,969 | British chemist Humphry Davy, who performed a number of experiments aimed to isolate the metal, is credited as the person who named the element. 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 Philosophic... | https://en.wikipedia.org/wiki?curid=904 |
18,970 | One example was "Essai sur la Nomenclature chimique" (July 1811), written in French by a Swedish chemist, Jöns Jacob Berzelius, in which the name "aluminium" is given to the element that would be synthesized from alum. (Another article in the same journal issue also gives the name "aluminium" to the metal whose oxide i... | https://en.wikipedia.org/wiki?curid=904 |
18,971 | In 1812, a British scientist, Thomas Young, wrote an anonymous review of Davy's book, in which he proposed the name "aluminium" instead of "aluminum", which he thought had a "less classical sound". This name did catch on: although the ' spelling was occasionally used in Britain, the American scientific language used ' ... | https://en.wikipedia.org/wiki?curid=904 |
18,972 | The International Union of Pure and Applied Chemistry (IUPAC) adopted "aluminium" as the standard international name for the element in 1990. In 1993, they recognized "aluminum" as an acceptable variant; the most recent 2005 edition of the IUPAC nomenclature of inorganic chemistry also acknowledges this spelling. IUPAC... | https://en.wikipedia.org/wiki?curid=904 |
18,973 | The production of aluminium starts with the extraction of bauxite rock from the ground. The bauxite is processed and transformed using the Bayer process into alumina, which is then processed using the Hall–Héroult process, resulting in the final aluminium metal. | https://en.wikipedia.org/wiki?curid=904 |
18,974 | Aluminium production is highly energy-consuming, and so the producers tend to locate smelters in places where electric power is both plentiful and inexpensive. As of 2019, the world's largest smelters of aluminium are located in China, India, Russia, Canada, and the United Arab Emirates, while China is by far the top p... | https://en.wikipedia.org/wiki?curid=904 |
18,975 | 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 . Much of this is in more-developed countries ( per capita) rather than less-developed countries ( per capita). | https://en.wikipedia.org/wiki?curid=904 |
18,976 | Bauxite is converted to alumina by the Bayer process. Bauxite is blended for uniform composition and then is ground. 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... | https://en.wikipedia.org/wiki?curid=904 |
18,977 | After this reaction, the slurry is at a temperature above its atmospheric boiling point. It is cooled by removing steam as pressure is reduced. The bauxite residue is separated from the solution and discarded. The solution, free of solids, is seeded with small crystals of aluminium hydroxide; this causes decomposition ... | https://en.wikipedia.org/wiki?curid=904 |
18,978 | The conversion of alumina to aluminium metal is achieved by the Hall–Héroult process. In this energy-intensive process, a solution of alumina in a molten () mixture of cryolite (NaAlF) with calcium fluoride is electrolyzed to produce metallic aluminium. The liquid aluminium metal sinks to the bottom of the solution and... | https://en.wikipedia.org/wiki?curid=904 |
18,979 | 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. 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 pre... | https://en.wikipedia.org/wiki?curid=904 |
18,980 | The Hall–Heroult process produces aluminium with a purity of above 99%. Further purification can be done by the Hoopes process. This process involves the electrolysis of molten aluminium with a sodium, barium, and aluminium fluoride electrolyte. The resulting aluminium has a purity of 99.99%. | https://en.wikipedia.org/wiki?curid=904 |
18,981 | Electric power represents about 20 to 40% of the cost of producing aluminium, depending on the location of the smelter. Aluminium production consumes roughly 5% of electricity generated in the United States. Because of this, alternatives to the Hall–Héroult process have been researched, but none has turned out to be ec... | https://en.wikipedia.org/wiki?curid=904 |
18,982 | Recovery of the metal through recycling has become an important task of the aluminium industry. Recycling was a low-profile activity until the late 1960s, when the growing use of aluminium beverage cans brought it to public awareness. Recycling involves melting the scrap, a process that requires only 5% of the energy u... | https://en.wikipedia.org/wiki?curid=904 |
18,983 | White dross from primary aluminium production and from secondary recycling operations still contains useful quantities of aluminium that can be extracted industrially. The process produces aluminium billets, together with a highly complex waste material. This waste is difficult to manage. It reacts with water, releasin... | https://en.wikipedia.org/wiki?curid=904 |
18,984 | The global production of aluminium in 2016 was 58.8 million metric tons. It exceeded that of any other metal except iron (1,231 million metric tons). | https://en.wikipedia.org/wiki?curid=904 |
18,985 | Aluminium is almost always alloyed, which markedly improves its mechanical properties, especially when tempered. For example, the common aluminium foils and beverage cans are alloys of 92% to 99% aluminium. The main alloying agents are copper, zinc, magnesium, manganese, and silicon (e.g., duralumin) with the levels of... | https://en.wikipedia.org/wiki?curid=904 |
18,986 | The great majority (about 90%) of aluminium oxide is converted to metallic aluminium. 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 oxide is commonly ... | https://en.wikipedia.org/wiki?curid=904 |
18,987 | Several sulfates of aluminium have industrial and commercial application. Aluminium sulfate (in its hydrate form) is produced on the annual scale of several millions of metric tons. About two-thirds is consumed in water treatment. The next major application is in the manufacture of paper. It is also used as a mordant i... | https://en.wikipedia.org/wiki?curid=904 |
18,988 | Aluminizing is the process of coating a structure or material with a thin layer of aluminium. It is done to impart specific traits that the underlying substrate lacks, such as a certain chemical or physical property. Aluminized materials include: | https://en.wikipedia.org/wiki?curid=904 |
18,989 | Despite its widespread occurrence in the Earth's crust, aluminium has no known function in biology. 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 sulfate has a... | https://en.wikipedia.org/wiki?curid=904 |
18,990 | Aluminium is classified as a non-carcinogen by the United States Department of Health and Human Services. A review published in 1988 said that there was little evidence that normal exposure to aluminium presents a risk to healthy adult, and a 2014 multi-element toxicology review was unable to find deleterious effects o... | https://en.wikipedia.org/wiki?curid=904 |
18,991 | Aluminium, although rarely, can cause vitamin D-resistant osteomalacia, erythropoietin-resistant microcytic anemia, and central nervous system alterations. People with kidney insufficiency are especially at a risk. Chronic ingestion of hydrated aluminium silicates (for excess gastric acidity control) may result in alum... | https://en.wikipedia.org/wiki?curid=904 |
18,992 | During the 1988 Camelford water pollution incident people in Camelford had their drinking water contaminated with aluminium sulfate for several weeks. A final report into the incident in 2013 concluded it was unlikely that this had caused long-term health problems. | https://en.wikipedia.org/wiki?curid=904 |
18,993 | Aluminium has been suspected of being a possible cause of Alzheimer's disease, but research into this for over 40 years has found, , no good evidence of causal effect. | https://en.wikipedia.org/wiki?curid=904 |
18,994 | Aluminium increases estrogen-related gene expression in human breast cancer cells cultured in the laboratory. In very high doses, aluminium is associated with altered function of the blood–brain barrier. A small percentage of people have contact allergies to aluminium and experience itchy red rashes, headache, muscle p... | https://en.wikipedia.org/wiki?curid=904 |
18,995 | Exposure to powdered aluminium or aluminium welding fumes can cause pulmonary fibrosis. Fine aluminium powder can ignite or explode, posing another workplace hazard. | https://en.wikipedia.org/wiki?curid=904 |
18,996 | Food is the main source of aluminium. Drinking water contains more aluminium than solid food; however, aluminium in food may be absorbed more than aluminium from water. Major sources of human oral exposure to aluminium include food (due to its use in food additives, food and beverage packaging, and cooking utensils), d... | https://en.wikipedia.org/wiki?curid=904 |
18,997 | Consumption of antacids, antiperspirants, vaccines, and cosmetics provide possible routes of exposure. 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. | https://en.wikipedia.org/wiki?curid=904 |
18,998 | 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. However, this should be applied with caution as this reduces not only aluminium body levels, but also those of other metals such as co... | https://en.wikipedia.org/wiki?curid=904 |
18,999 | 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 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. | https://en.wikipedia.org/wiki?curid=904 |
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