Cobalt Chemische Eigenschaften,Einsatz,Produktion Methoden
ERSCHEINUNGSBILD
SILBERGRAUES PULVER.
PHYSIKALISCHE GEFAHREN
Staubexplosion der pulverisierten oder granulierten Substanz in Gemischen mit Luft möglich..
CHEMISCHE GEFAHREN
Kann sich beim Kontakt mit Luft spontan entzünden. Reagiert mit starken Oxidationsmitteln unter Feuer- und Explosionsgefahr.
ARBEITSPLATZGRENZWERTE
TLV: 0.02 mg/m?(als TWA); Krebskategorie: A3; BEI vorhanden; (ACGIH 2005).
MAK: (Einatembare Fraktion) Sensibilisierung der Atemwege und der Haut; Krebserzeugend Kategorie 2; Keimzellmutagen Kategorie 3A; (DFG 2005).
AUFNAHMEWEGE
Aufnahme in den Körper durch Inhalation.
INHALATIONSGEFAHREN
Eine gesundheitsschädliche Partikelkonzentration in der Luft kann beim Dispergieren schnell erreicht werden.
WIRKUNGEN BEI KURZZEITEXPOSITION
WIRKUNGEN BEI KURZZEITEXPOSITION: Die Substanz (als Rauch oder Staub) reizt leicht die Atemwege.
WIRKUNGEN NACH WIEDERHOLTER ODER LANGZEITEXPOSITION
Wiederholter oder andauernder Hautkontakt kann zu Hautsensibilisierung führen. Wiederholte oder andauernde Inhalation kann asthmatische Beschwerden hervorrufen. Risiko der Lungenschädigung bei wiederholter oder längerer Exposition. Möglicherweise krebserzeugend für den Menschen.
LECKAGE
Verschüttetes Material in Behältern sammeln; falls erforderlich durch Anfeuchten Staubentwicklung verhindern. Reste sorgfältig sammeln. An sicheren Ort bringen. NICHT in die Umwelt gelangen lassen. Persönliche Schutzausrüstung: Atemschutzgerät, P3-Filter für giftige Partikel.
R-Sätze Betriebsanweisung:
R45:Kann Krebs erzeugen.
R23/24/25:Giftig beim Einatmen, Verschlucken und Berührung mit der Haut.
R34:Verursacht Verätzungen.
R53:Kann in Gewässern längerfristig schädliche Wirkungen haben.
R42/43:Sensibilisierung durch Einatmen und Hautkontakt möglich.
R40:Verdacht auf krebserzeugende Wirkung.
R36/37:Reizt die Augen und die Atmungsorgane.
R36/38:Reizt die Augen und die Haut.
R17:Selbstentzündlich an der Luft. Spontaneously flammable in air.
S-Sätze Betriebsanweisung:
S53:Exposition vermeiden - vor Gebrauch besondere Anweisungen einholen.
S23:Gas/Rauch/Dampf/Aerosol nicht einatmen(geeignete Bezeichnung(en) vom Hersteller anzugeben).
S26:Bei Berührung mit den Augen sofort gründlich mit Wasser abspülen und Arzt konsultieren.
S36/37/39:Bei der Arbeit geeignete Schutzkleidung,Schutzhandschuhe und Schutzbrille/Gesichtsschutz tragen.
S45:Bei Unfall oder Unwohlsein sofort Arzt zuziehen (wenn möglich, dieses Etikett vorzeigen).
S61:Freisetzung in die Umwelt vermeiden. Besondere Anweisungen einholen/Sicherheitsdatenblatt zu Rate ziehen.
S37:Geeignete Schutzhandschuhe tragen.
S24:Berührung mit der Haut vermeiden.
S22:Staub nicht einatmen.
S36/37:Bei der Arbeit geeignete Schutzhandschuhe und Schutzkleidung tragen.
S5:Unter . . . aufbewahren (geeignete Flüssigkeit vom Hersteller anzugeben).
Beschreibung
Cobalt was discovered by George Brandt in 1737. Cobalt exists
in valence states from 0 to 5, with the most stable (+2 and +3)
being the most common. Although there is only one stable
isotope of cobalt, there are a number of unstable isotopes. Two
of these, cobalt-60 and cobalt-57, are in use commercially.
Cobalt-60 is used for cancer treatment and food irradiation.
Cobalt-57 has research applications.
Chemische Eigenschaften
Cobalt is a silver-gray to black, hard, brittle, magnetic metal. It is relatively rare; the important mineral sources are the arsenides, sulfides, and oxidized forms. It is generally obtained as a by-product of other metals, particularly copper. The fume and dust of cobalt metal is odorless and black. The appearance and odor of cobalt compounds and their dusts and fumes vary with the compound. Cobalt metal in powdered form is incompatible with fused ammonium nitrate, hydrozinium nitrate, and strong oxidizing agents and should be avoided. It ignites on contact with bromide pentafl uoride. Powdered cobalt ignites spontaneously in air. Exposure to cobalt metal fume and dust can occur through inhalation, ingestion, and eye or skin contact.
Physikalische Eigenschaften
Cobalt is a bluish steel-gray metal that can be polished to a bright shine. It is brittle andis not malleable unless alloyed with other metals. It is magnetic, and when alloyed with aluminum and nickel, it is called alnico metal, which acts as a super-magnet with many uses inindustry. Chemically and physically, cobalt acts much as do its two partners, iron (Fe) andnickel (Ni), located on each side of it in period 4 on the periodic table. In particular, iron,cobalt, and nickelare unique in that they possess natural magnetic properties. Cobalt’s meltingpoint is 1,495°C, its boiling point is 2,927°C, and its density is 8.86 g/cm
3.
Isotopes
There are 33 isotopes of cobalt, ranging from Co-48 to Co-75, with half-livesranging from a few nanoseconds to 5.272 years for cobalt-60. Cobalt-59 is the onlystable isotope that constitutes almost all (roughly 100%) of the element’s natural presence on Earth. All the other isotopes are radioactive and are created artificially in nuclearreactors or nuclear explosions.
Origin of Name
Cobalt was given the name kobolds (or kolalds, or kololos) by German
miners. It means “goblin” (see “History” for more on this story).
Occurrence
Cobalt is the 32nd most abundant element on Earth even though it makes up only 0.003%of the Earth’s crust. It is not found in the free metallic state, despite being widely distributedin igneous rocks as minerals. Its two most common mineral ores are cobaltite (CoAsS) anderythrite [Co
3(AsO
4)
2]. These ores are placed in blast furnaces to produce cobalt arsenide(Co
2As), which is then treated with sulfuric acid to remove the arsenic. Finally, the productcobalt tetraoxide (Co
3O
4) is reduced by heat with carbon (Co
3O
4 + C → 3Co + 2CO
2), resulting in cobalt metal.Cobalt is also found in seawater, meteorites, and other ores such as linnaeite, chloanthite,and smaltite, and traces are found mixed with the ores of silver, copper, nickel, zinc, andmanganese. Cobalt ores are found in Canada and parts of Africa, but most of the cobalt usedin the United States is recovered as a by-product of the mining, smelting, and refining of theores of iron, nickel, lead, copper, and zinc.
Charakteristisch
Cobalt has the highest Curie point of any metal or alloy of cobalt. The Curie point is thetemperature at which an element will lose its magnetism before it reaches its melting point.Cobalt’s Curie point is 1,121°C, and its melting point is 1,495°C. About 25% of all cobaltmined in the world is used as an alloy with other metals. The most important is the alloyalnico, which consists of nickel, aluminum, and cobalt. Alnico is used to make powerful permanent magnets with many uses, such as CT, PET, and MRI medical instruments. It is alsoused for electroplating metals to give a fine surface that resists oxidation.
Verwenden
For alloys; manufacture of cobalt salts; in nuclear technology. Since 60Co can be encapsulated compactly, it has replaced radium in experimental medicine and cancer research. Cobalt is also used in the cobalt bomb, a hydrogen bomb surrounded by a cobalt metal shell. When the nuclear explosion occurs 60Co is formed from 59Co by neutron capture. Considered a "dirty bomb" because of long half-life and intense b- and g radiation. Max permissible concentration of 60Co in air: 10-7mCi/cc, Natl. Bur. Stand. Handb. 69, 31 (1959).
Definition
ChEBI: A cobalt group element atom that has atomic number 27.
Vorbereitung Methode
World sources of the metal and the oxide are chiefly from
Zaire, Belgium–Luxembourg, Norway, and Finland, in that
order, with Zaire furnishing 58% of the world’s supply.
Practically all cobalt produced is a by- or coproduct of
other metals, chiefly copper; accordingly, a description of the
mining process is omitted. The processes used in extracting
cobalt from its ores vary according to the type of ore and
locations of the ore deposit.
Arsenical ores are concentrated by hand sorting, gravity
separation, or froth flotation, and are smelted in a blast
furnace with coke and limestone to a speiss (an impure
mixture of iron, cobalt, and nickel arsenides). The speiss is
ground, roasted with salt, and leached with water. Insoluble
chlorides remaining after the leaching process are
ground with sulfuric acid, washed, and filtered, and the
washings are added to the liquid from the leaching step.
The combined solution is oxidized and then neutralized
with lime.
Basic ferric arsenate precipitates and is removed, leaving
a solution-containing cobalt and nickel. The addition of
successive portions of sodium hydroxide and sodium hypochlorite
precipitates cobalt as the hydroxide, which is
initially pure but finally admixes with nickel hydroxide.
The cobalt precipitate is dried, ground, and formed into
pellets, which are reduced by heating with charcoal to
cobalt metal.
Reaktionen
Cobalt absorbs very little hydrogen even at high temperatures and nitrogen is practically
insoluble up to 1200°C. Finely divided cobalt is pyrophoric in air, but the massive metal
is scarcely attacked below 300°C. The oxide scale on cobalt heated in air or oxygen up to
900° consists of an outside layer of CO3O4 and a layer of CoO next to the metal ; above
900°, Co3O4 decomposes and the scale consists of CoO only. Cobalt reacts with many
non-metals when heated, e.g. the halogens, boron, sulphur, phosphorus, arsenic and
antimony, the reactions often proceeding with incandescence. Fluorine forms CoF3, while
the other halogens give the cobalt(II) halide.
Weltgesundheitsorganisation (WHO)
WHO Comment(non-radioactive forms): The World Health Organization has no information further to the
above regarding preparations containing cobalt or to indicate that they are still
commercially manufactured.
Air & Water Reaktionen
Burns brilliantly when exposed to air [Mellor 14:453(1946-1947)]. Insoluble in water.
Reaktivität anzeigen
Pyrophoric Cobalt is a reducing agent. Decomposes acetylene in the cold as the metal becomes incandescent [Mellor 14:513(1946-1947]. Incompatible with oxidizing agents such as ammonium nitrate, bromine pentafluoride, and nitryl fluoride.
Hazard
Cobalt is found in most natural foods. Although a necessary trace element, it is toxic to humans if ingested in large amounts. The human body does excrete in urine excessive amounts of cobalt compounds such as found in vitamin B12.
Cobaltous chromate (CoCrO
4) is brownish-yellow to grayish-black (the color depends on its purity) is a dangerous carcinogen (causes cancer).
Some years ago, a cobalt additive was used by some beer makers to maintain a foam head on their beer. Those who imbibed excessively developed what is known as beer drinkers syndrome, which caused some deaths from enlarged and flabby hearts.
Health Hazard
Cobalt is an essential element. Its deficiencycan result in pernicious anemia. It is present invitamin B12. Excessive intake of this elementmay result in polycythemia or overproductionof erythrocytes and heart lesions. Exposure toits dusts can produce cough and respiratoryirritation. Chronic inhalation of its dusts orfumes can decrease pulmonary functions andmay cause diffuse nodular fibrosis and otherpulmonary diseases. Skin contact may inducedermal hypersensitivity reactions, producingan allergy-type dermatitis.
Co(II) ion is reported to be genotoxicin vitro and in vivo and carcinogenic inrodents (De Boeck et al. 2003) Occupationalexposure to hard metal (cemented carbide)dust is linked to an increased risk of lungcancer.
Brandgefahr
Literature sources indicate that the dust of Cobalt is flammable.
Industrielle Verwendung
Cobalt (symbol Co) is a lustrous, silvery-bluemetallic chemical element, resembling nickelbut with a bluish tinge instead of the yellow ofnickel. It is rarer and costlier than nickel andits price has varied widely in recent years.Although allied to nickel, it has distinctive differences.It is more active chemically thannickel. It is dissolved by dilute H2SO4, HNO3,or HCl acids, and is attacked slowly by alkalis.The oxidation rate of pure cobalt is 25 timesthat of nickel. Its power of whitening copperalloys is inferior to that of nickel, but smallamounts in Ni–Cu alloys will neutralize theyellowish tinge of the nickel and make themwhiter. The metal is diamagnetic like nickel, buthas three times the maximum permeability.Like tungsten, it imparts red-hardness to toolsteels. It also hardens alloys to a greater extentthan nickel, especially in the presence of carbon,and can form more chemical compoundsin alloys than nickel.
Its chemical properties resemble, in part,those of both nickel and iron. Cobalt is themetal with the highest Curie temperature(1121°C) and the lowest allotropic transformationtemperature (399°C). Below 421°C, cobaltis close-packed hexagonal; above, it is facecenteredcubic.
Biologische Aktivität
Cobalt is a vital trace element in animal nutrition. Ruminants grazing upon cobaltdeficient pastures exhibit retarded growth, loss of appetite and anaemia ; rapid recovery from these symptoms occurs upon feeding the animals with a cobalt-supplemented diet. Cobalt salts are not therefore considered to be particularly toxic to animals, but to man they can in sufficiently large doses irritate the gastro-intestinal tract and cause nausea, vomiting and diarrhoea. Small amounts of cobalt, however, are invaluable in the treatment of pernicious anaemia. The discovery in 1926 of the antipernicious anaemia factor in liver led to the discovery in 1948 of vitamin B12, which was very soon after shown to contain cobalt.
Sicherheitsprofil
Confirmed carcinogen
with experimental neoplastigenic and
tumorigenic data. Poison by intravenous,
intratracheal, and intraperitoneal routes.
Moderately toxic by ingestion. Inhalation of
the dust may cause pulmonary damage. The
powder may cause dermatitis. Ingestion of
soluble salts produces nausea and vomiting
by local irritation. Powdered cobalt igmtes
spontaneously in air. Flammable when
exposed to heat or flame. Explosive reaction
with hydrazinium nitrate, ammonium nitrate
+ heat, and 1,3,4,7-tetramethylisoindole (at
39OOC). Ignites on contact with bromine
pentafluoride. Incandescent reaction with
acetylene or nitryl fluoride. See also
COBALT COMPOUNDS.
mögliche Exposition
Possible risk of forming tumors, Suspected reprotoxic hazard. Nickel-aluminumcobalt alloys are used for permanent magnets. Alloys with nickel, aluminum, copper, beryllium, chromium, and molybdenum are used in the electrical, automobile, and aircraft industries. Cobalt is added to tool steels to improve their cutting qualities and is used as a binder in the manufacture of tungsten carbide tools. Various cobalt compounds are used as pigments in enamels, glazes, and paints; as catalysts in afterburners; and in the glass, pottery, photographic, electroplating industries. Radioactive cobalt (60Co) is used in the treatment of cancer. Cobalt has been added to beer to promote formation of foam but cobalt acts with alcohol to produce severe cardiac effects at concentrations as low as 1.2-1.5 mg/L of beer. Cobalt is part of the vitamin B12 molecule and as such is an essential nutrient. The requirement of humans for cobalt in the form of vitamin B12 is about 0.13 μg/day.
Carcinogenicity
In mammalian cells in vitro cobalt compounds
have caused DNA strand breaks, sister
chromatid exchanges, and aneuploidy, but
not chromosomal aberrations.Cobalt salts
are generally nonmutagenic in prokaryotic
assays.
Environmental Fate
Cobalt most often depresses the activity of enzymes, including
catalase, amino levulinic acid synthetase, and P-450, enzymes
involved in cellular respiration. The Krebs citric acid cycle can
be blocked by cobalt resulting in the inhibition of cellular
energy production. Cobalt can replace zinc in a number of zincrequired
enzymes such as alcohol dehydrogenase. Cobalt can
also enhance the kinetics of some enzymes, such as heme
oxidase in the liver. Cobalt interferes with and depresses iodine
metabolism, resulting in reduced thyroid activity. Reduced
thyroid activity can lead to goiter.
Lager
Cobalt metal dust (powdered metal) should be stored in a cool, dry, well-ventilated area in
tightly sealed containers that are labeled in accordance with OSHA standards. Containers
of cobalt metal dust should be protected from physical damage and ignition sources, and
should be stored separately from strong oxidizers.
Versand/Shipping
UN3189 Metal powder, self-heating, n.o.s., Hazard Class: 4.2; Labels: 4.2-Spontaneously combustible material
Waste disposal
Cobalt metal may be recovered from scrap and cobalt compounds from spent catalysts as alternatives to disposal.
Cobalt Upstream-Materialien And Downstream Produkte
Upstream-Materialien
Downstream Produkte
