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 was
first recognized by the Romans as an astringent substance, and
they called it ‘alum.’ By the middle ages it was manufactured as
‘alum stone,’ a subsulfate of alumina and potash. In 1825, Hans
C. ?ersted was able to isolate a few drops of the raw material,
and by 1886 it had patents from both Charles Martin Hall of the
United States and Paul-Louis-Toussaint Heroult of France.
Aluminum was commercialized in industry by the end of the
nineteenth 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
Pure metallic aluminum is not found in nature. It is found as a part of compounds,especially compounded with oxygen as in aluminum oxide (Al
2O
3). 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/cm
3.
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)
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 a
bitter 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 (Al
2O
3) is the fourth mostabundant compound found on Earth, with a weight of 69,900 ppm. Another alum-typecompound is potassium aluminum sulfate [KAl(SO
4)
2?12H
2O]. 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 medicine
as an astringent, and as a mordant in dyeing. In 1761 de
Morveau proposed the name alumine for the base in alum,
and Lavoisier, in 1787, thought this to be the oxide of a still
undiscovered metal. Wohler is generally credited with having
isolated the metal in 1827, although an impure form was prepared
by Oersted two years earlier. In 1807, Davy proposed
the 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 elsewhere
in the world. Aluminium was also the accepted spelling
in the U.S. until 1925, at which time the American Chemical
Society officially decided to use the name aluminum thereafter
in their publications. The method of obtaining aluminum
metal by the electrolysis of alumina dissolved in cryolite was
discovered in 1886 by Hall in the U.S. and at about the same
time by Heroult in France. Cryolite, a natural ore found in
Greenland, 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 hydrated
oxide ore, is found in large deposits in Jamaica, Australia,
Suriname, Guyana, Russia, Arkansas, and elsewhere. The
Bayer process is most commonly used today to refine bauxite
so it can be accommodated in the Hall–Heroult refining
process used to make most aluminum. Aluminum can now
be produced from clay, but the process is not economically
feasible at present. Aluminum is the most abundant metal to
be found in the Earth’s crust (8.1%), but is never found free
in nature. In addition to the minerals mentioned above, it is
found in feldspars, granite, and in many other common minerals.
Twenty-two isotopes and isomers are known. Natural
aluminum 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 be
formed, machined, or cast, has a high thermal conductivity,
and has excellent corrosion resistance. It is nonmagnetic and
nonsparking, stands second among metals in the scale of malleability,
and sixth in ductility. It is extensively used for kitchen
utensils, outside building decoration, and in thousands of industrial
applications where a strong, light, easily constructed
material is needed. Although its electrical conductivity is only
about 60% that of copper, it is used in electrical transmission
lines because of its light weight. Pure aluminum is soft and
lacks strength, but it can be alloyed with small amounts of
copper, magnesium, silicon, manganese, and other elements
to impart a variety of useful properties. These alloys are of
vital importance in the construction of modern aircraft and
rockets. Aluminum, evaporated in a vacuum, forms a highly
reflective coating for both visible light and radiant heat. These
coatings soon form a thin layer of the protective oxide and do
not deteriorate as do silver coatings. They have found application
in coatings for telescope mirrors, in making decorative
paper, packages, toys, and in many other uses. The compounds
of greatest importance are aluminum oxide, the sulfate, and
the soluble sulfate with potassium (alum). The oxide, alumina,
occurs naturally as ruby, sapphire, corundum, and emery, and
is used in glassmaking and refractories. Synthetic ruby and
sapphire have found application in the construction of lasers
The Elements 4-3
for producing coherent light. In 1852, the price of aluminum
was about $1200/kg, and just before Hall’s discovery in 1886,
about $25/kg. The price rapidly dropped to 60￠ and has been
as low as 33￠/kg. The price in December 2001 was about 64￠/
lb or $1.40/kg.
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.
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.
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(Al
2O
3) 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.
Production Methods
Aluminum production involves four main steps: bauxite
mining,refining of bauxite to yield alumina; electrolytic
reduction of alumina to yield aluminum; and aluminum
casting into ingots.
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.
Agricultural Uses
Aluminum, the third most abundant element in the earth’s
crust, is a silvery-white lustrous metal belonging to
Group 13 of the Periodic Table. The metal is
highly reactive and is protected by a thick transparent
oxide layer that gets formed quickly in air. Aluminum
and its oxides are amphoteric.
Pure aluminum, which exists in a large number of
alloys, is extracted from purified bauxite by electrolysis.
Its lightness, strength (when alloyed), corrosion
resistance and electrical conductivity make aluminum
suitable for a variety of uses, including in the
construction of vehicles, aircrafts, buildings and
overhead power cables.
Aluminum (Al) is an important soil constituent. It is
toxic to most plants at a soil pH below 6.0.
Aluminum ion forms octahedral coordination with
water molecules and hydroxyl ions. If soil is not strongly
acidic, one (or more) of the water molecules ionizes,
releasing the hydrogen ion (H
+)in to the solution and
increasing the soil acidity.
The toxic level of soluble and exchangeable
aluminum can be substantially reduced by first raising the
soil pH in the range of 5.2 to 5.5 and by further liming to
make it in the range of 6.0 to 6.5.
In acidic soils, aluminum may compete for uptake
with copper and make the soil copper deficient.
Molybdenum is adsorbed strongly by oxides of
aluminum and iron, thereby making the molybdenum
unavailable to plants. Increasing aluminum in the soil
solution also restricts the uptake of calcium and
magnesium by plants.
Aluminum ions are toxic to the roots of many plants
such as cotton, tomato, alfalfa, celery, barley, corn,
sorghum, and sugar beets. Aluminum toxicity is
probably the most important growth limiting factor in
many acid soils.
The symptoms of aluminum toxicity caused
by excess soluble aluminum are not easily recognize
in crop plants. White-yellow interveinal blotches
form on leaves causing them to dry out and die.
Aluminum toxicity also reduces the growth of both shoots
and roots.
An excess of aluminum interferes with cell division in
plant roots, inhibits nodule initiation (by fixing the soil
phosphorus to forms that are less available to plant roots),
and decreases root respiration. Aluminum interferes with
enzymes controlling the deposition of polysaccharides in
cell walls and increases cell wall rigidity by cross-linking
with pectins. It reduces the uptake, transport, and use of
nutrients and water by the plant.
Aluminum-injured roots are characteristically stubby
and brittle. The root tips and lateral roots thicken and
turn brown. The root system as a whole, appears
coralline, with many stubby lateral roots but no fine
branching.
The toxicity problem of aluminum is not
economically correctable with conventional liming
practices. A genetic approach has the potential to solve
the 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-difluorotetrafluoroethane, fluorotrichloroethane, hexachloroethane + alcohol, polytrifluoroethylene oils and greases, tetrachloroethylene, tetrafluoromethane, 1,1,1trichloroethane, trichloroethylene, 1,1,2trichlorotrifluoro-ethane, and trichlorotrifluoroethane-dchlorobenzene. Potentially explosive reaction with chloroform amidinium nitrate. Ignites on contact with vapors of AsCl3, SC4, Se2Cl2, and PCl5. Reacts violently on heating with Sb or As. Ignites on heating in SbCl3 vapor. Ignites on contact with barium peroxide. Potentially violent reaction with sodium acetylide. Mixture with sodum peroxide may ignite or react violently. Spontaneously igmtes in CS2 vapor. Halogens: ignites in Powdered aluminum undergoes the
chlorine gas, foil reacts vigorously with liquid Br2, violent reaction with H20 + 12. Violent reaction with hydrochloric acid, hydro-fluoric acid, and hydrogen chloride gas. Violent reaction with disulfur dbromide. Violent reaction with the nonmetals phosphorus, sulfur, and selenium. Violent reaction or ignition with the interhalogens: bromine pentafluoride, chlorine fluoride, iodne chloride, iodine pentafluoride, and iodne heptafluoride. Burns when heated in CO2. Ignites on contact with O2, and mixtures with O2 + H20 ignite and react violently. Mixture with picric acid + water ignites after a delay period. Explosive reaction above 800°C with sodium sulfate. Violent reaction with sulfur when heated. Exothermic reaction with iron powder + water releases explosive hydrogen gas. Aluminum powder also forms sensitive explosive mixtures with oxidants such as: liquid Cl2 and other halogens, N2O4, tetranitromethane, bromates, iodates, NaClO3, KClO3, and other chlorates, NaNO3, aqueous nitrates, KClO4 and other perchlorate salts, nitryl fluoride, ammonium peroxodisulfate, sodium peroxide, zinc peroxide, and other peroxides, red phosphorus, and powdered polytetrafluoroethylene (PTFE).
following dangerous interactions: exothermic reaction with butanol, methanol, 2-propanol, or other alcohols, sodium hydroxide to release explosive hydrogen gas. Reaction with dborane forms pyrophoric product. Ignition on contact with niobium oxide + sulfur. Explosive reaction with molten metal oxides, oxosalts (nitrates, sulfates), sulfides, and sodium carbonate. Reaction with arsenic trioxide + sodum arsenate + sodium hydroxide produces the toxic arsine gas. Violent reaction with chlorine trifluoride. Incandescent reaction with formic acid. Potentially violent alloy formation with palladium, platinum at mp of Al, 600℃. Vigorous dssolution reaction in Bulk aluminum may undergo the
ALUMINUM CHLORIDE HYDROXIDE AHAOOO 45
methanol + carbon tetrachloride. Vigorous amalgamation reaction with mercury(Ⅱ) salts + moisture. Violent reaction with molten silicon steels. Violent exothermic reaction above 600℃ with sodium diuranate.
Potential Exposure
Most hazardous exposures to aluminum occur in smelting and refining processes. Aluminum is mostly produced by electrolysis of Al2O3 dissolved in molten cryolite (Na3AlF6). Aluminum is alloyed with copper, zinc, silicon, magnesium, manganese, and nickel; special additives may include chromium, lead, bismuth, titanium, zirconium, and vanadium. Aluminum and its alloys can be extruded or processed in rolling mills, wire works, forges, or foundries; and are used in the shipbuilding, electrical, building, aircraft, automobile, light engineering, and jewelry industries. Aluminum foil is widely used in packaging. Powdered aluminum is used in the paints and pyrotechnic industries. Alumina, emery, and corundum has been used for abrasives, refractories, and catalysts; and in the past in the first firing of china and pottery.
Carcinogenicity
Most animal studies have failed to demonstrate carcinogenicity
attributable to aluminum administered by various
routes in rats, rabbits, mice, and guinea pigs. Some of
these studies even suggested some antitumor activity.
However, aluminum was found to cause cancer in a few
experimental studies such as sarcomas in rats when
implanted subcutaneously. This observation was attributed
to the dimensions of the implants rather than the
chemical composition.
Significantly increased incidence of gross tumors was
reported in male Long Evans rats and lymphoma leukemia
in female Swiss mice given aluminum potassium sulfate in
drinking water respectively for 2–2.5 years. A
dose–response relationship could not be determined for
either species because only one dose of aluminum was
used and the type of tumors and organs in which they
were found were not specified.
Environmental Fate
Aluminum binds diatomic phosphates and possibly depletes
phosphate, which can lead to osteomalacia. High aluminum
serum values and high aluminum concentration in the bone
interfere with the function of vitamin D. The incorporation of
aluminum in the bone may interfere with deposition of
calcium; the subsequent increase of calcium in the blood may
inhibit release of parathyroid hormones by the parathyroid
gland. The mechanism by which aluminum concentrates in the
brain is not known; it may interfere with the blood brain barrier.
storage
Aluminum metallic powder should be kept stored in a tightly closed container, in a cool, dry, ventilated area, protected against physical damage and isolated from sources of heat, ignition, smoking areas, and moisture. Aluminum metallic powder should be kept away from acidic, alkaline, combustible, and oxidizing materials and separate from halogenated compounds.
Shipping
UN1309 Aluminum powder, coated, Hazard Class: 4.1; Labels: 4.1-Flammable solid. UN1383 Pyrophoric metals, n.o.s. or Pyrophoric alloys, n.o.s., Hazard Class: 4.2; Labels: 4.2-Spontaneously combustible material, Technical Name Required. UN1396 Aluminum powder, uncoated, Hazard Class: 4.3; Labels: 4.3-Dangerous when wet material. NA9260 (North America) Aluminum, molten, Hazard class: 9; Labels: 9-Miscellaneous hazardous material.
Structure and conformation
The space lattice of Al belongs to the cubic system, and its face centered cubic lattice has a lattice constant of a=0.404145 nm (25 ℃).
Toxicity evaluation
Aluminum cannot be degraded in the environment in its
elemental state, but can undergo various precipitation or
ligand exchange reactions. The solubility of aluminum in the
environment depends on the ligands present and the pH.
Long-range transport
The major feature cycle of aluminum include leaching of
aluminum from geochemical formations and soil particulates
to aqueous environments, adsorption onto soil or
sediment particulates, and wet and dry deposition from the
air to land and surface water.
Bioaccumulation and biomagnification
Aluminum does not bioaccumulate to a significant extent.
Thus, certain plants can accumulate high concentrations of
aluminum. Plant matter like tea leaves may contain
>5000 mg kg
-1 of aluminum. Lycopodium, some fern
species, and members of genera Symplocos or Orites may
contain high levels of aluminum. It does not appear to
accumulate to any significant degree in cow’s milk or beef
tissue, and it is therefore not expected to undergo
biomagnification in terrestrial food chains.
Incompatibilities
Aluminum powder forms an explosive mixture with air and is a strong reducing agent that reacts violently with oxidizers, strong bases; strong acids; somehalogenated hydrocarbons; nitrates, sulfates, metal oxides and many other substances. Keep away from combustible materials.
Waste Disposal
Consult with environmental regulatory agencies for guidance on acceptable disposalpractices. Generators of waste containing this contaminant (≥100 kg/mo) must conform with EPA regulations governing storage, transportation, treatment, and waste disposal of Aluminum Oxide-Disposal in a sanitary landfill. Mixing of industrial process wastes and municipal wastes at such sites is not encouraged however. Aluminum powder may be recovered and sold as scrap. Recycling and recovery is a viable option to disposal for aluminum metal and aluminum fluoride (A-57).
Precautions
The dry powder is stable but the damp or moist bulk dust may heat spontaneously and
form flammable hydrogen gas. Moist aluminum powder may ignite in air, with the formation of flammable hydrogen gas and a combustible dust. Powdered material may form
explosive dust-air mixtures. Contact with water, strong acids, strong bases, or alcohols
releases flammable hydrogen gas. The dry powder can react violently or explosively with
many inorganic and organic chemicals
