Aluminum CAS 7429-90-5
Introduction：Basic information about Aluminum CAS 7429-90-5, including its chemical name, molecular formula, synonyms, physicochemical properties, and safety information, etc.
Aluminum Basic informationDescription Production Methods
| Product Name: | Aluminum |
| Synonyms: | ALUMINIUM(WELDINDFUMES);ALMINIUM(PYROPOWDER);Aluminum slug, 3.175mm (0.125in) dia x 6.35mm (0.25 in) length, Puratronic|r, 99.9998% (metals basis);Aluminum slug, 3.175mm (0.125in) dia x 3.175mm (0.125in) length, Puratronic|r, 99.9999% (metals basi;Aluminum wire, 1.5mm (0.059in) dia, annealed, Puratronic, 99.999% (metals basis);Aluminum wire, 2.0mm (0.08in) dia, annealed, Puratronic, 99.9995% (metals basis);Aluminum slug, 3.175mm (0.125in) dia x 3.175mm (0.125in) length, Puratronic, 99.9995% (metals basis);Aluminum slug, 3.175mm (0.125in) dia x 6.35mm (0.25in) length, Puratronic, 99.999% (metals basis) |
| CAS: | 7429-90-5 |
| MF: | Al |
| MW: | 26.98 |
| EINECS: | 231-072-3 |
| Product Categories: | Inorganics;Industrial/Fine Chemicals;Analytical Reagents;Replacement Kit Items;Water Test;AluminumOrganic Electronics and Photonics;Electrode Materials;Substrates and Electrode Materials;A;AA to ALCertified Reference Materials (CRMs);Alphabetic;Application CRMs;Industrial Raw MaterialsReference/Calibration Standards;IRMM/BCR Certified Reference Materials;Matrix CRMs;Reactor DosimetryCertified Reference Materials (CRMs);Reactor Neutron Dosimetry;Reactor Neutron DosimetryCertified Reference Materials (CRMs);ACS GradeChemical Synthesis;Essential Chemicals;Routine Reagents;13: Al;AluminumMaterials Science;Nanomaterials;Nanoparticles: Metals and Metal AlloysNanomaterials;Nanopowders and Nanoparticle Dispersions;metal or element;Films and Foils;Labware;Aluminum;AluminumMetal and Ceramic Science;Catalysis and Inorganic Chemistry;Chemical Synthesis;Metals;Metal and Ceramic Science |
| Mol File: | 7429-90-5.mol |
Aluminum Chemical Properties
| Melting point | 660.37 °C (lit.) |
| Boiling point | 2460 °C (lit.) |
| bulk density | 0.77g/cm3 |
| density | 2.7 g/mL at 25 °C (lit.) |
| vapor pressure | 0.13-1300Pa at 974℃ |
| Fp | 400°C |
| storage temp. | Flammables area |
| solubility | insoluble in H2O; soluble in acid solutions, alkaline solutions |
| form | wire |
| color | Yellow |
| Specific Gravity | 2.702 (Water=1) |
| Odor | Odorless |
| PH | 0.5 (H2O, 20°C) |
| Flame Color | Silvery-white |
| biological source | goat |
| resistivity | 2.6548 μΩ-cm |
| Water Solubility | Insoluble in water. |
| Sensitive | Moisture Sensitive |
| Merck | 13,321 / 13,321 |
| Exposure limits | TLV-TWA 10 mg/m3 (Al dust), 5 mg/m3(pyrophoric Al powder and welding fumes),2 mg/m3 (soluble Al salts and alkyls)(ACGIH). |
| Dielectric constant | 1.6-1.8（0.0℃） |
| Stability: | Stable. Powder is flammable. Reacts very exothermically with halogens. Moisture and air sensitive. Incompatible with strong acids, caustics, strong oxidizing agents, halogenated hydrocarbons. |
| Major Application | battery manufacturing |
| Cosmetics Ingredients Functions | COLORANT |
| InChI | 1S/Al |
| InChIKey | XAGFODPZIPBFFR-UHFFFAOYSA-N |
| SMILES | [Al] |
| Shear Modulus | 25.0 GPa |
| Poissons Ratio | 0.36, calculated |
| Modulus of Elasticity | 68.0 GPa |
| Hardness, Vickers | 15, Annealed |
| CAS DataBase Reference | 7429-90-5(CAS DataBase Reference) |
| NIST Chemistry Reference | Aluminum(7429-90-5) |
| EPA Substance Registry System | Aluminum (7429-90-5) |
Safety Information
| Hazard Codes | F,Xi,Xn,N |
| Risk Statements | 17-15-36/38-10-67-65-62-51/53-48/20-38-11-50 |
| Safety Statements | 7/8-43A-43-26-62-61-36/37-33-29-16-9 |
| RIDADR | 1396 |
| OEB | B |
| OEL | TWA: 10 mg/m3 (total) |
| WGK Germany | 3 |
| RTECS | BD0330000 |
| Autoignition Temperature | 400 °C |
| TSCA | TSCA listed |
| HazardClass | 8 |
| PackingGroup | III |
| HS Code | 76032000 |
| Storage Class | 11 - Combustible Solids |
| Hazardous Substances Data | 7429-90-5(Hazardous Substances Data) |
| Toxicity | An element that isabundant (about 8%) in the crust of the earth. Aluminumappears to have no biological function and, from the point ofview of acute toxicity, is essentially non-toxic. Because it isprimarily eliminated by excretion, people with compromisedkidney function may accumulate the metal. In kidney dialysispatients, this is a particular problem because the dialyzingsolution may contain high concentrations of aluminum. Thiscondition (dialysis encephalopathy or dialysis dementia) hassymptoms that include impaired memory, EEG changes,dementia, aphasia, ataxia, and convulsions.One possiblemechanism of toxicity may be inhibition of hexokinases in thebrain. The chelating agent deferoxamine has been used successfullyin treating this condition.Aluminum is one of the primary toxicants leachedinto surface water (and, therefore, water supplies) by aciddeposition. The connection between aluminum and Alzheimersdisease is controversial and many investigators believe there isno connection. |
| Description | Aluminum is the third most abundant element in the crust of the earth, accounting for 8.13% by weight. It does not occur in free elemental form in nature, but is found in combined forms such as oxides or silicates. It occurs in many minerals including bauxite, cryolite, feldspar and granite. Aluminum alloys have innumerable application; used extensively in electrical transmission lines, coated mirrors, utensils, packages, toys and in construction of aircraft and rockets. aluminum powder |
| Production Methods | Most aluminum is produced from its ore, bauxite, which contains between 40 to 60% alumina either as the trihydrate, gibbsite, or as the monohydrate, boehmite, and diaspore. Bauxite is refined first for the removal of silica and other impurities. It is done by the Bayer process. Ground bauxite is digested with NaOH solution under pressure, which dissolves alumina and silica, forming sodium aluminate and sodium aluminum silicate. Insoluble residues containing most impurities are filtered out. The clear liquor is then allowed to settle and starch is added to precipitate.The residue, so-called “red-mud”, is filtered out. After this “desilication,” the clear liquor is diluted and cooled. It is then seeded with alumina trihydrate (from a previous run) which promotes hydrolysis of the sodium aluminate to produce trihydrate crystals. The crystals are filtered out, washed, and calcined above 1,100°C to produce anhydrous alumina. The Bayer process, however, is not suitable for extracting bauxite that has high silica content (>10%). In the Alcoa process, which is suitable for highly silicious bauxite, the “red mud” is mixed with limestone and soda ash and calcined at 1,300°C. This produces “lime-soda sinter” which is cooled and treated with water. This leaches out water-soluble sodium alumnate, leaving behind calcium silicate and other impurites. Alumina may be obtained from other minerals, such as nepheline, sodium potassium aluminum silicate, by similar soda lime sintering process.Metal aluminum is obtained from the pure alumina at 950 to 1000°C electrolysis (Hall-Heroult process). Although the basic process has not changed since its discovery, there have been many modifications. Aluminum is also produced by electrolysis of anhydrous AlCl3. Also, the metal can be obtained by nonelectrolytic reduction processes. In carbothermic process, alumina is heated with carbon in a furnace at 2000 to 2500°C. Similarly, in “Subhalide” process, an Al alloy, Al-Fe-Si-, (obtained by carbothermic reduction of bauxite) is heated at 1250°C with AlCl vapor. This forms the subchloride (AlCl), the vapor of which decomposes when cooled to 800°C. |
| Description | Although aluminum was one of the last metals to be commercialized,it has been recognized for centuries. Aluminum wasfirst recognized by the Romans as an astringent substance, andthey called it ‘alum.’ By the middle ages it was manufactured as‘alum stone,’ a subsulfate of alumina and potash. In 1825, HansC. ?ersted was able to isolate a few drops of the raw material,and by 1886 it had patents from both Charles Martin Hall of theUnited States and Paul-Louis-Toussaint Heroult of France.Aluminum was commercialized in industry by the end of thenineteenth century. |
| Chemical Properties | Aluminum metallic powder is a light, silvery-white to gray, odorless powder. Aluminum metallic powder is reactive and flammable. Aluminum is normally coated with a layer of aluminum oxide unless the particles are freshly formed. There are two main types of aluminum powder: the “fl ake” type made by stamping the cold metal and the “granulated” type made from molten aluminum. Pyro powder is an especially fi ne type of “fl ake” powder. Aluminum powders are used in paints, pigments, protective coatings, printing inks, rocket fuel, explosives, abrasives, and ceramics; the production of inorganic and organic aluminum chemicals; and as catalysts. Pyro powder is mixed with carbon and used in the manufacture of fi reworks. The coarse powder is used in aluminothermics. |
| Physical properties | Emissivity of Al Clean polished foil: 0.04 (300 K), 0.02 (78 K), 0.011 (2 K, λ: 14 mm) Electrolytic polished Al after annealing: 0.07 (1000 K), 0.04 (500 K), 0.03 (300 K) Commercial products: 0.09 (373 K) |
| Physical properties | Pure metallic aluminum is not found in nature. It is found as a part of compounds,especially compounded with oxygen as in aluminum oxide (Al2O3). In its purified form, aluminumis a bluish-white metal that has excellent qualities of malleability and ductility. Purealuminum is much too soft for construction or other purposes. However, adding as little as1% each of silicon and iron will make aluminum harder and give it strength. Its melting point is 660.323°C, its boiling point is 2,519°C, and its density is 2.699 g/cm3. |
| Isotopes | There are 23 isotopes of aluminum, and only one of these is stable. The singlestable isotope, Al-27, accounts for 100% of the element’s abundance in the Earth’scrust. All the other isotopes are radioactive with half-lives ranging from a few nanosecondsto 7.17×10+15 years. |
| Origin of Name | From the Latin word alumen, or aluminis, meaning “alum,” which is abitter tasting form of aluminum sulfate or aluminum potassium sulfate. |
| Occurrence | Aluminum is the third most abundant element found in the Earth’s crust. It is found inconcentrations of 83,200 ppm (parts-per-million) in the crust. Only the nonmetals oxygenand silicon are found in greater abundance. Aluminum oxide (Al2O3) is the fourth mostabundant compound found on Earth, with a weight of 69,900 ppm. Another alum-typecompound is potassium aluminum sulfate [KAl(SO4)2?12H2O]. Although aluminum is notfound in its free metallic state, it is the most widely distributed metal (in compound form) onEarth. Aluminum is also the most abundant element found on the moon. Almost all rocks contain some aluminum in the form of aluminum silicate minerals foundin clays, feldspars, and micas. Today, bauxite is the major ore for the source of aluminummetal. Bauxite was formed eons ago by the natural chemical reaction of water, which thenformed aluminum hydroxides. In addition to the United States, Jamaica and other Caribbeanislands are the major sources of bauxite. Bauxite deposits are found in many countries, butnot all are of high concentration. |
| Characteristics | Alloys of aluminum are light and strong and can easily be formed into many shapes—thatis, it can be extruded, rolled, pounded, cast, and welded. It is a good conductor of electricityand heat. Aluminum wires are only about 65% as efficient in conducting electricity as arecopper wires, but aluminum wires are significantly lighter in weight and less expensive thancopper wires. Even so, aluminum wiring is not used in homes because of its high electricalresistance, which can build up heat and may cause fires. Aluminum reacts with acids and strong alkali solutions. Once aluminum is cut, the freshsurface begins to oxidize and form a thin outer coating of aluminum oxide that protects themetal from further corrosion. This is one reason aluminum cans should not be discarded inthe environment. Aluminum cans last for many centuries (though not forever) because atmosphericgases and soil acids and alkalis react slowly with it. This is also the reason aluminumis not found as a metal in its natural state. |
| History | The ancient Greeks and Romans used alum in medicineas an astringent, and as a mordant in dyeing. In 1761 deMorveau proposed the name alumine for the base in alum,and Lavoisier, in 1787, thought this to be the oxide of a stillundiscovered metal. Wohler is generally credited with havingisolated the metal in 1827, although an impure form was preparedby Oersted two years earlier. In 1807, Davy proposedthe name alumium for the metal, undiscovered at that time,and later agreed to change it to aluminum. Shortly thereafter,the name aluminium was adopted to conform with the “ium”ending of most elements, and this spelling is now in use elsewherein the world. Aluminium was also the accepted spellingin the U.S. until 1925, at which time the American ChemicalSociety officially decided to use the name aluminum thereafterin their publications. The method of obtaining aluminummetal by the electrolysis of alumina dissolved in cryolite wasdiscovered in 1886 by Hall in the U.S. and at about the sametime by Heroult in France. Cryolite, a natural ore found inGreenland, is no longer widely used in commercial production,but has been replaced by an artificial mixture of sodium,aluminum, and calcium fluorides. Bauxite, an impure hydratedoxide ore, is found in large deposits in Jamaica, Australia,Suriname, Guyana, Russia, Arkansas, and elsewhere. TheBayer process is most commonly used today to refine bauxiteso it can be accommodated in the Hall–Heroult refiningprocess used to make most aluminum. Aluminum can nowbe produced from clay, but the process is not economicallyfeasible at present. Aluminum is the most abundant metal tobe found in the Earth’s crust (8.1%), but is never found freein nature. In addition to the minerals mentioned above, it isfound in feldspars, granite, and in many other common minerals.Twenty-two isotopes and isomers are known. Naturalaluminum is made of one isotope, 27Al. Pure aluminum, a silvery-white metal, possesses many desirable characteristics.It is light, nontoxic, has a pleasing appearance, can easily beformed, machined, or cast, has a high thermal conductivity,and has excellent corrosion resistance. It is nonmagnetic andnonsparking, stands second among metals in the scale of malleability,and sixth in ductility. It is extensively used for kitchenutensils, outside building decoration, and in thousands of industrialapplications where a strong, light, easily constructedmaterial is needed. Although its electrical conductivity is onlyabout 60% that of copper, it is used in electrical transmissionlines because of its light weight. Pure aluminum is soft andlacks strength, but it can be alloyed with small amounts ofcopper, magnesium, silicon, manganese, and other elementsto impart a variety of useful properties. These alloys are ofvital importance in the construction of modern aircraft androckets. Aluminum, evaporated in a vacuum, forms a highlyreflective coating for both visible light and radiant heat. Thesecoatings soon form a thin layer of the protective oxide and donot deteriorate as do silver coatings. They have found applicationin coatings for telescope mirrors, in making decorativepaper, packages, toys, and in many other uses. The compoundsof greatest importance are aluminum oxide, the sulfate, andthe soluble sulfate with potassium (alum). The oxide, alumina,occurs naturally as ruby, sapphire, corundum, and emery, andis used in glassmaking and refractories. Synthetic ruby andsapphire have found application in the construction of lasersThe Elements 4-3for producing coherent light. In 1852, the price of aluminumwas about $1200/kg, and just before Hall’s discovery in 1886,about $25/kg. The price rapidly dropped to 60￠ and has beenas low as 33￠/kg. The price in December 2001 was about 64￠/lb or $1.40/kg. |
| Uses | As pure metal or alloys (magnalium, aluminum bronze, etc.) for structural material in construction, automotive, electrical and aircraft industries. In cooking utensils, highway signs, fencing, containers and packaging, foil, machinery, corrosion resistant chemical equipment, dental alloys. The coarse powder in aluminothermics (thermite process); the fine powder as flashlight in photography; in explosives, fireworks, paints; for absorbing occluded gases in manufacture of steel. In testing for Au, As, Hg; coagulating colloidal solutions of As or Sb; pptg Cu; reducer for determining nitrates and nitrites; instead of Zn for generating hydrogen in testing for As. Forms complex hydrides with lithium and boron, such as LiAlH4, which are used in preparative organic chemistry. |
| Uses | Aluminum is a very versatile metal with many uses in today’s economy, the most common ofwhich are in construction, in the aviation-space industries, and in the home and automobile industries.Its natural softness is overcome by alloying it with small amounts of copper or magnesium thatgreatly increase its strength. It is used to make cans for food and drinks, in pyrotechnics, for protectivecoatings, to resist corrosion, to manufacture die-cast auto engine blocks and parts, for homecooking utensils and foil, for incendiary bombs, and for all types of alloys with other metals. Aluminum does not conduct electricity as well as copper, but because it is much lighter inweight, it is used for transmission lines, though not in household wiring. A thin coating ofaluminum is spread on glass to make noncorroding mirrors. Pure oxide crystals of aluminumare known as corundum, which is a hard, white crystal and one of the hardest substancesknown. Corundum finds many uses in industry as an abrasive for sandpaper and grindingwheels. This material also resists heat and is used for lining high-temperature ovens, to formthe white insulating part of spark plugs, and to form a protective coating on many electronicdevices such a transistors.Aluminum oxide is used to make synthetic rubies and sapphires for lasers beams. It hasmany pharmaceutical uses, including ointments, toothpaste, deodorants, and shaving creams. |
| Uses | Aluminum finds wide applications for industrialand domestic purposes. Fine powder isused in explosives, in fireworks, as flashlightsin photography, and in aluminumpaints. It is commonly used in alloys withother metals and is nonhazardous as alloys. |
| Production Methods | Aluminum production involves four main steps: bauxitemining,refining of bauxite to yield alumina; electrolyticreduction of alumina to yield aluminum; and aluminumcasting into ingots. |
| Definition | aluminium: Symbol Al. A silverywhitelustrous metallic element belongingto group 3 (formerly IIIB) ofthe periodic table; a.n. 13; r.a.m.26.98; r.d. 2.7; m.p. 660°C; b.p.2467°C. The metal itself is highly reactivebut is protected by a thintransparent layer of the oxide, whichforms quickly in air. Aluminium andits oxide are amphoteric. The metalis extracted from purified bauxite(Al2O3) by electrolysis; the mainprocess uses a Hall–Heroult cell butother electrolytic methods are underdevelopment, including conversionof bauxite with chlorine and electrolysisof the molten chloride. Pure aluminiumis soft and ductile but itsstrength can be increased by workhardening.A large number of alloysare manufactured; alloying elementsinclude copper, manganese, silicon,zinc, and magnesium. Its lightness,strength (when alloyed), corrosion resistance,and electrical conductivity(62% of that of copper) make it suitablefor a variety of uses, includingvehicle and aircraft construction,building (window and door frames),and overhead power cables. Althoughit is the third most abundantelement in the earth’s crust (8.1% byweight) it was not isolated until 1825by H. C. Oersted. |
| General Description | Aluminum metal held above melting point of 1220°F (660°C) for ease in handling. Cools and solidifies if released. Contact causes thermal burns. Plastic or rubber may melt or lose strength upon contact. Protective equipment designed for chemical exposure only is not effective against direct contact. Take care walking on the surface of a spill to avoid stepping into a pocket of molten aluminum below the crust. Do not attempt to remove aluminum impregnated clothing because of the danger of tearing flesh if there has been a burn. |
| Air & Water Reactions | Violent reaction with water; contact may cause an explosion or may produce a flammable gas (hydrogen). Moist air produces hydrogen gas. Does not burn on exposure to air. |
| Reactivity Profile | ALUMINUM , MOLTEN, is a reducing agent. Coating moderates or greatly moderates its chemical reactivity compared to the uncoated material. Reacts exothermically if mixed with metal oxides and heated (thermite process). Heating a mixture with copper oxides caused a strong explosion [Mellor 5:217-19 1946-47]. Reacts with metal salts, mercury and mercury compounds, nitrates, sulfates, halogens, and halogenated hydrocarbons to form compounds that are sensitive to mechanical shock [Handling Chemicals Safely 1980. p. 135]. A number of explosions in which ammonium nitrate and powdered aluminum were mixed with carbon or hydrocarbons, with or without oxidizing agents, have occurred [Mellor 5:219 1946-47]. A mixture with powdered ammonium persulfate and water may explode [NFPA 491M 1991]. Heating a mixture with bismuth trioxide leads to an explosively violent reaction [Mellor 9:649 (1946-47)]. Mixtures with finely divided bromates(also chlorates and iodates) of barium, calcium, magnesium, potassium, sodium or zinc can explode by heat, percussion, and friction, [Mellor 2:310 (1946-47]. Burns in the vapor of carbon disulfide, sulfur dioxide, sulfur dichloride, nitrous oxide, nitric oxide, or nitrogen peroxide, [Mellor 5:209-212,1946-47]. A mixture with carbon tetrachloride exploded when heated to 153° C and also by impact, [Chem. Eng. News 32:258 (1954)]; [UL Bull. Research 34 (1945], [ASESB Pot. Incid. 39 (1968)]. Mixing with chlorine trifluoride in the presence of carbon results in a violent reaction [Mellor 2 Supp. 1: 1956]. Ignites in close contact with iodine. Three industrial explosions involving a photoflash composition containing potassium perchlorate with aluminum and magnesium powder have occurred [ACS 146:210 1945], [NFPA 491M 1991]. Is attacked by methyl chloride in the presence of small amounts of aluminum chloride to give flammable aluminum trimethyl. Give a detonable mixture with liquid oxygen [NFPA 491M 1991]. The reaction with silver chloride, once started, proceeds with explosive violence [Mellor 3:402 1946-47]. In an industrial accident, the accidental addition of water to a solid mixture of sodium hydrosulfite and powdered aluminum caused the generation of SO2, heat and more water. The aluminum powder reacted with water and other reactants to generate more heat, leading to an explosion that killed five workers [Case Study, Accident Investigation: Napp Technologies, 14th International Hazardous Material Spills Conference]. |
| Hazard | Aluminum dust and fine powder are highly explosive and can spontaneously burst intoflames in air. When treated with acids, aluminum chips and coarse powder release hydrogen.The heat from the chemical reaction can then cause the hydrogen to burn or explode. Purealuminum foil or sheet metal can burn in air when exposed to a hot enough flame. Fumesfrom aluminum welding are toxic if inhaled. |
| Health Hazard | Exposures to aluminum metallic powder have been known to cause health effects with symptoms such as irritation, redness, and pain to the eyes, coughing, shortness of breath, irritation to the respiratory tract, nausea, and vomiting in extreme cases. In prolonged periods of inhalation exposures, as in occupational situations, aluminum metallic powder is known to cause pulmonary fi brosis, numbness in fi ngers, and (in limited cases) brain effects. Workers with pre-existing skin disorders, eye problems, or impaired respiratory function are known to be more susceptible to the effects of aluminum metallic powder. |
| Fire Hazard | Substance is transported in molten form at a temperature above 705°C (1300°F). Violent reaction with water; contact may cause an explosion or may produce a flammable gas. Will ignite combustible materials (wood, paper, oil, debris, etc.). Contact with nitrates or other oxidizers may cause an explosion. Contact with containers or other materials, including cold, wet or dirty tools, may cause an explosion. Contact with concrete will cause spalling and small pops. |
| reaction suitability | reagent type: catalyst core: aluminum |
| Agricultural Uses | Aluminum, the third most abundant element in the earth’scrust, is a silvery-white lustrous metal belonging toGroup 13 of the Periodic Table. The metal ishighly reactive and is protected by a thick transparentoxide layer that gets formed quickly in air. Aluminumand its oxides are amphoteric. Pure aluminum, which exists in a large number ofalloys, is extracted from purified bauxite by electrolysis.Its lightness, strength (when alloyed), corrosionresistance and electrical conductivity make aluminumsuitable for a variety of uses, including in theconstruction of vehicles, aircrafts, buildings andoverhead power cables. Aluminum (Al) is an important soil constituent. It istoxic to most plants at a soil pH below 6.0. Aluminum ion forms octahedral coordination withwater molecules and hydroxyl ions. If soil is not stronglyacidic, one (or more) of the water molecules ionizes,releasing the hydrogen ion (H+)in to the solution andincreasing the soil acidity. The toxic level of soluble and exchangeablealuminum can be substantially reduced by first raising thesoil pH in the range of 5.2 to 5.5 and by further liming tomake it in the range of 6.0 to 6.5. In acidic soils, aluminum may compete for uptakewith copper and make the soil copper deficient.Molybdenum is adsorbed strongly by oxides ofaluminum and iron, thereby making the molybdenumunavailable to plants. Increasing aluminum in the soilsolution also restricts the uptake of calcium andmagnesium by plants. Aluminum ions are toxic to the roots of many plantssuch as cotton, tomato, alfalfa, celery, barley, corn,sorghum, and sugar beets. Aluminum toxicity isprobably the most important growth limiting factor inmany acid soils. The symptoms of aluminum toxicity causedby excess soluble aluminum are not easily recognizein crop plants. White-yellow interveinal blotchesform on leaves causing them to dry out and die.Aluminum toxicity also reduces the growth of both shootsand roots. An excess of aluminum interferes with cell division inplant roots, inhibits nodule initiation (by fixing the soilphosphorus to forms that are less available to plant roots),and decreases root respiration. Aluminum interferes withenzymes controlling the deposition of polysaccharides incell walls and increases cell wall rigidity by cross-linkingwith pectins. It reduces the uptake, transport, and use ofnutrients and water by the plant. Aluminum-injured roots are characteristically stubbyand brittle. The root tips and lateral roots thicken andturn brown. The root system as a whole, appearscoralline, with many stubby lateral roots but no finebranching. The toxicity problem of aluminum is noteconomically correctable with conventional limingpractices. A genetic approach has the potential to solvethe problem of aluminum toxicity in acid soils. |
| Industrial uses | Alloying aluminum with various elementsmarkedly improves mechanical properties,strength primarily, at only a slight sacrifice indensity, thus increasing specific strength, orstrength-to-weight ratio. Traditionally, wroughtalloys have been produced by thermomechanicallyprocessing cast ingot into mill productssuch as billet, bar, plate, sheet, extrusions, andwire. For some alloys, however, such mill productsare now made by similarly processing“ingot” consolidated from powder. Such alloysare called PM (powder metal) wrought alloysor simply PM alloys. To distinguish the traditionaltype from these, they are now sometimesreferred to as ingot-metallurgy (IM) alloys oringot-cast alloys. Another class of PM alloysare those used to make PM parts by pressingand sintering the powder to near-net shape.There are also many cast alloys. All told, thereare about 100 commercial aluminum alloys. |
| Safety Profile | Although aluminum is not generally regarded as an industrial poison, inhalation of finely dwided powder has been reported to cause pulmonary fibrosis. It is a reactive metal and the greatest industrial hazards are with chemical reactions. As with other metals the powder and dust are the most dangerous forms. Dust is moderately flammable and explosive by heat, flame, or chemical reaction with powerful oxidizers. To fight fire, use special mixtures of dry chemical. following dangerous interactions: explosive reaction after a delay period with KClO4 + Ba(NO3)2 + mo3 + H20, also with Ba(NO3)2 + mo3 + sulfur + vegetable adhesives + H2O. Wxtures with powdered AgCl, NH4NO3 or NH4NO3 + Ca(NO3)2 + formamide + H20 are powerful explosives. Murture with ammonium peroxodisulfate + water is explosive. Violent or explosive "thermite" reaction when heated with metal oxides, oxosalts (nitrates, sulfates), or sulfides, and with hot copper oxide worked with an iron or steel tool. Potentially explosive reaction with ccl4 during ball milling operations. Many violent or explosive reactions with the following halocarbons have occurred in industry: bromomethane, bromotrifluoromethane, ccl4, chlorodfluoromethane, chloroform, chloromethane, chloromethane + 2methylpropane, dchlorodifluoromethane, 1,2-dichloroethane, dichloromethane, 1,2dichloropropane, 1,2-difluorotet
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