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= Cobalt =
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Introduction
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Cobalt is a chemical element; it has symbol Co and atomic number 27.
As with nickel, cobalt is found in the Earth's crust only in a
chemically combined form, save for small deposits found in alloys of
natural meteoric iron. The free element, produced by reductive
smelting, is a hard, lustrous, somewhat brittle, gray metal.
Cobalt-based blue pigments (cobalt blue) have been used since
antiquity for jewelry and paints, and to impart a distinctive blue
tint to glass. The color was long thought to be due to the metal
bismuth. Miners had long used the name 'kobold ore' (German for
'goblin ore') for some of the blue pigment-producing minerals. They
were so named because they were poor in known metals and gave off
poisonous arsenic-containing fumes when smelted. In 1735, such ores
were found to be reducible to a new metal (the first discovered since
ancient times), which was ultimately named for the 'kobold'.
Today, cobalt is usually produced as a by-product of copper and nickel
mining, but sometimes also from one of a number of metallic-lustered
ores such as cobaltite (CoAsS). The Copperbelt in the Democratic
Republic of the Congo (DRC) and Zambia yields most of the global
cobalt production. World production in 2016 was 116,000 t according to
Natural Resources Canada, and the DRC alone accounted for more than
50%. In 2024, production exceeded 300,000 tons, of which DRC accounted
for more than 80%.
Cobalt is primarily used in lithium-ion batteries, and in the
manufacture of magnetic, wear-resistant and high-strength alloys. The
compounds cobalt silicate and cobalt(II) aluminate (CoAl2O4, cobalt
blue) give a distinctive deep blue color to glass, ceramics, inks,
paints and varnishes. Cobalt occurs naturally as only one stable
isotope, cobalt-59. Cobalt-60 is a commercially important
radioisotope, used as a radioactive tracer and for the production of
high-energy gamma rays. Cobalt is also used in the petroleum industry
as a catalyst when refining crude oil. This is to purge it of sulfur,
which is very polluting when burned and causes acid rain.
Cobalt is the active center of a group of coenzymes called cobalamins.
Vitamin B, the best-known example of the type, is an essential vitamin
for all animals. Cobalt in inorganic form is also a micronutrient for
bacteria, algae, and fungi.
The name cobalt derives from a type of ore considered a nuisance by
16th century German silver miners, which in turn may have been named
from a spirit or goblin held superstitiously responsible for it; this
spirit is considered equitable to the kobold (a household spirit) by
some, or, categorized as a gnome (mine spirit) by others.
Characteristics
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Cobalt is a ferromagnetic metal with a specific gravity of 8.9. The
Curie temperature is 1115 C and the magnetic moment is 1.6-1.7 Bohr
magnetons per atom. Cobalt has a relative permeability two-thirds that
of iron. Metallic cobalt occurs as two crystallographic structures:
hcp and fcc. The ideal transition temperature between the hcp and fcc
structures is 450 C, but in practice the energy difference between
them is so small that random intergrowth of the two is common.
Cobalt is a weakly reducing metal that is protected from oxidation by
a passivating oxide film. It is attacked by halogens and sulfur.
Heating in oxygen produces Co3O4 which loses oxygen at 900 C to give
the monoxide CoO. The metal reacts with fluorine (F2) at 520 K to give
CoF3; with chlorine (Cl2), bromine (Br2) and iodine (I2), producing
equivalent binary halides. It does not react with hydrogen gas (H2) or
nitrogen gas (N2) even when heated, but it does react with boron,
carbon, phosphorus, arsenic and sulfur. At ordinary temperatures, it
reacts slowly with mineral acids, and very slowly with moist, but not
dry, air.
Compounds
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Cobalt tool tip
Common oxidation states of cobalt include +2 and +3, although
compounds with oxidation states ranging from −3 to +5 are also known.
A common oxidation state for simple compounds is +2 (cobalt(II)).
These salts form the pink-colored metal aquo complex in water.
Addition of chloride gives the intensely blue . In a borax bead flame
test, cobalt shows deep blue in both oxidizing and reducing flames.
Oxygen and chalcogen compounds
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Several oxides of cobalt are known. Green cobalt(II) oxide (CoO) has
rocksalt structure. It is readily oxidized with water and oxygen to
brown cobalt(III) hydroxide (Co(OH)3). At temperatures of 600-700 °C,
CoO oxidizes to the blue cobalt(II,III) oxide (Co3O4), which has a
spinel structure. Black cobalt(III) oxide (Co2O3) is also known.
Cobalt oxides are antiferromagnetic at low temperature: CoO (Néel
temperature 291 K) and Co3O4 (Néel temperature: 40 K), which is
analogous to magnetite (Fe3O4), with a mixture of +2 and +3 oxidation
states.
The principal chalcogenides of cobalt are the black cobalt(II)
sulfides, CoS2 (pyrite structure), (spinel structure), and CoS
(nickel arsenide structure).
Halides
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Four dihalides of cobalt(II) are known: cobalt(II) fluoride (CoF2,
pink), cobalt(II) chloride (CoCl2, blue), cobalt(II) bromide (CoBr2,
green), cobalt(II) iodide (CoI2, blue-black). These halides exist in
anhydrous and hydrated forms. Whereas the anhydrous dichloride is
blue, the hydrate is red.
The reduction potential for the reaction + e− → is +1.92 V, beyond
that for chlorine to chloride, +1.36 V. Consequently, cobalt(III)
chloride would spontaneously reduce to cobalt(II) chloride and
chlorine. Because the reduction potential for fluorine to fluoride is
so high, +2.87 V, cobalt(III) fluoride is one of the few simple stable
cobalt(III) compounds. Cobalt(III) fluoride, which is used in some
fluorination reactions, reacts vigorously with water.
Coordination compounds
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The inventory of complexes is very large. Starting with higher
oxidation states, complexes of Co(IV) and Co(V) are rare. Examples are
found in caesium hexafluorocobaltate(IV) (Cs2CoF6) and potassium
percobaltate (K3CoO4).
Cobalt(III) forms a wide variety of coordination complexes with
ammonia and amines, which are called ammine complexes. Examples
include , (chloropentamminecobalt(III)), and 'cis'- and 'trans'-. The
corresponding ethylenediamine complexes are also well known.
Analogues are known where the halides are replaced by nitrite,
hydroxide, carbonate, etc. Alfred Werner worked extensively on these
complexes in his Nobel-prize winning work. The robustness of these
complexes is demonstrated by the optical resolution of
tris(ethylenediamine)cobalt(III) ().
Cobalt(II) forms a wide variety of complexes, but mainly with weakly
basic ligands. The pink-colored cation hexaaquocobalt(II) is found
in several routine cobalt salts such as the nitrate and sulfate. Upon
addition of excess chloride, solutions of the hexaaquo complex
converts to the deep blue , which is tetrahedral.
Softer ligands like triphenylphosphine form complexes with Co(II) and
Co(I), examples being bis- and tris(triphenylphosphine)cobalt(I)
chloride, and . These Co(I) and Co(II) complexes represent a link to
the organometallic complexes described below.
Organometallic compounds
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Cobaltocene is a structural analog to ferrocene, with cobalt in place
of iron. Cobaltocene is much more sensitive to oxidation than
ferrocene. Cobalt carbonyl (Co2(CO)8) is a catalyst in carbonylation
and hydrosilylation reactions. Vitamin B12 (see below) is an
organometallic compound found in nature and is the only vitamin that
contains a metal atom. An example of an alkylcobalt complex in the
otherwise uncommon +4 oxidation state of cobalt is the homoleptic
complex tetrakis(1-norbornyl)cobalt(IV) (Co(1-norb)4), a transition
metal-alkyl complex that is notable for its resistance to β-hydrogen
elimination, in accord with Bredt's rule. The cobalt(III) and
cobalt(V) complexes and are also known.
Isotopes
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59Co is the only stable cobalt isotope and the only isotope that
exists naturally on Earth. Twenty-two radioisotopes have been
characterized: the most stable, 60Co, has a half-life of 5.2714 years;
57Co has a half-life of 271.8 days; 56Co has a half-life of 77.27
days; and 58Co has a half-life of 70.86 days. All the other
radioactive isotopes of cobalt have half-lives shorter than 18 hours,
and in most cases shorter than 1 second. This element also has 4 meta
states, all of which have half-lives shorter than 15 minutes.
The isotopes of cobalt range in atomic mass from (50Co) to (73Co).
The primary decay mode for isotopes with atomic masses less than that
of the only stable isotope, 59Co, is electron capture and the primary
mode of decay in isotopes with atomic mass greater than is beta
decay. The primary decay products below 59Co are element 26 (iron)
isotopes; above that the decay products are element 28 (nickel)
isotopes.
Because 59Co is a nucleus of spin 7/2 and 100% abundancy, it is
possible to detect it using nuclear magnetic resonance spectroscopy.
The nucleus has a magnetic quadrupole moment. Among all NMR active
nuclei, 59Co has the largest chemical shift range and the chemical
shift can be correlated with the spectrochemical series. Resonances
are observed over a range of 20000 ppm, the width of the signals being
up to 20 kHz. A widely used standard is potassium hexacyanocobaltate
(0.1M in ), which, due to its high symmetry, has a rather small line
width. Systems of low symmetry can yield broadened signals to an
extent that renders the signals unobservable in fluid phase NMR, but
still observable in solid state NMR.
Etymology
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Many different stories about the origin of the word "cobalt" have been
proposed. In one version the element 'cobalt' was named after "", the
name which 16th century German silver miners had given to a nuisance
type of ore which occurred that was corrosive and issued poisonous
gas. Although such ores had been used for blue pigmentation since
antiquity, the Germans at that time did not have the technology to
smelt the ore into metal (cf. below).
The authority on such 'kobelt' ore (Latinized as 'cobaltum' or
'cadmia') at the time was Georgius Agricola. He was also the
oft-quoted authority on the mine spirits called "" (Latinized as
'cobalus' or pl. 'cobali') in a separate work.
Agricola did not make a connection between the similarly named ore and
spirit. However, a causal connection (ore blamed on "kobel") was made
by a contemporary, and a word origin connection (word "formed" from
'cobalus') made by a late 18th century writer. Later, Grimms'
dictionary (1868) noted the 'kobalt/kobelt' ore was blamed on the
mountain spirit () which was also held responsible for "stealing the
silver and putting out an ore that caused poor mining atmosphere
('Wetter') and other health hazards".
Grimms' dictionary entries equated the word "kobel" with "kobold", and
listed it as a mere variant diminutive, but the latter is defined in
it as a household spirit. Whereas some of the more recent commentators
prefer to characterize the ore's namesake 'kobelt' (recté 'kobel') as
a gnome.
The early 20th century 'Oxford English Dictionary' (1st edition, 1908)
had upheld Grimm's etymology. However, by around the same time in
Germany, the alternate etymology not endorsed by Grimm ('kob/kof'
"house, chamber" + 'walt' "power, ruler") was being proposed as more
convincing.
Somewhat later, Paul Kretschmer (1928) explained that while this
"house ruler" etymology was the proper one that backed the original
meaning of kobold as household spirit, a corruption later occurred
introducing the idea of "mine demon" to it. The present edition of the
'Etymologisches Wörterbuch' (25th ed., 2012) under "kobold" lists the
latter, not Grimm's etymology, but still persists, under its entry for
"kobalt", that while the cobalt ore may have got its name from "a type
of mine spirit/demon" ('daemon metallicus') while stating that this is
"apparently" the kobold.
Joseph William Mellor (1935) also stated that cobalt may derive from
'kobalos' (), though other theories had been suggested.
Alternate theories
====================
Several alternative etymologies that have been suggested, which may
not involve a spirit (kobel or kobold) at all. Karl Müller-Fraureuth
conjectured that 'kobelt' derived from ', a bucket used in mining,
frequently mentioned by Agricola, namely the 'kobel/köbel' (Latinized
as 'modulus').
Another theory given by the 'Etymologisches Wörterbuch' derives the
term from or rather (, "arsenic sulfide") which occurs as noxious
fumes.
An etymology from Slavonic ' was suggested by Emanuel Merck (1902).
W. W. Skeat and J. Berendes construed as "parasite", i.e. as an ore
parasitic to nickel, but this explanation is faulted for its
anachronism since nickel was not discovered until 1751.
History
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Cobalt compounds have been used for centuries to impart a rich blue
color to glass, glazes, and ceramics. Cobalt has been detected in
Egyptian sculpture, Persian jewelry from the third millennium BC, in
the ruins of Pompeii, destroyed in 79 AD, and in China, dating from
the Tang dynasty (618-907 AD) and the Ming dynasty (1368-1644 AD).
Cobalt has been used to color glass since the Bronze Age. The
excavation of the Uluburun shipwreck yielded an ingot of blue glass,
cast during the 14th century BC. Blue glass from Egypt was either
colored with copper, iron, or cobalt. The oldest cobalt-colored glass
is from the eighteenth dynasty of Egypt (1550-1292 BC). The source for
the cobalt the Egyptians used is not known.
The word 'cobalt' is derived from the 16th century German "", a type
of ore, as aforementioned. The first attempts to smelt those ores for
copper or silver failed, yielding simply powder (cobalt(II) oxide)
instead. Because the primary ores of cobalt always contain arsenic,
smelting the ore oxidized the arsenic into the highly toxic and
volatile arsenic oxide, adding to the notoriety of the ore.
Paracelsus, Georgius Agricola, and Basil Valentine all referred to
such silicates as "cobalt".
Swedish chemist Georg Brandt (1694-1768) is credited with discovering
cobalt , showing it to be a previously unknown element, distinct from
bismuth and other traditional metals. Brandt called it a new
"semi-metal",See also: (1) G. Brandt (1746) "Rön och anmärkningar
angäende en synnerlig färg--cobolt" (Observations and remarks
concerning an extraordinary pigment--cobalt), 'Kongliga Svenska
vetenskapsakademiens handlingar' (Transactions of the Royal Swedish
Academy of Science), vol. 7, pp. 119-130; (2) G. Brandt (1748)
"Cobalti nova species examinata et descripta" (Cobalt, a new element
examined and described), 'Acta Regiae Societatis Scientiarum
Upsaliensis' (Journal of the Royal Scientific Society of Uppsala), 1st
series, vol. 3, pp. 33-41; (3) James L. Marshall and Virginia R.
Marshall (Spring 2003)
[
https://web.archive.org/web/20100703175508/http://www.chem.unt.edu/Rediscovery/Riddarhyttan.pdf
"Rediscovery of the Elements: Riddarhyttan, Sweden"]. 'The Hexagon'
(official journal of the Alpha Chi Sigma fraternity of chemists), vol.
94, no. 1, pages 3-8. naming it for the mineral from which he had
extracted it.Weeks, M. E. (1968). Discovery of the elements. (H. M.
Leicester, Ed.; 7th ed.). Journal of chemical education.
He showed that compounds of cobalt metal were the source of the blue
color in glass, which previously had been attributed to the bismuth
found with cobalt. Cobalt became the first metal to be discovered
since the pre-historical period. All previously known metals (iron,
copper, silver, gold, zinc, mercury, tin, lead and bismuth) had no
recorded discoverers.
During the 19th century, a significant part of the world's production
of cobalt blue (a pigment made with cobalt compounds and alumina) and
smalt (cobalt glass powdered for use for pigment purposes in ceramics
and painting) was carried out at the Norwegian Blaafarveværket. The
first mines for the production of smalt in the 16th century were
located in Norway, Sweden, Saxony and Hungary. With the discovery of
cobalt ore in New Caledonia in 1864, the mining of cobalt in Europe
declined. With the discovery of ore deposits in Ontario, Canada, in
1904 and the discovery of even larger deposits in the Katanga Province
in the Congo in 1914, mining operations shifted again. When the Shaba
conflict started in 1978, the copper mines of Katanga Province nearly
stopped production. The impact on the world cobalt economy from this
conflict was smaller than expected: cobalt is a rare metal, the
pigment is highly toxic, and the industry had already established
effective ways for recycling cobalt materials. In some cases, industry
was able to change to cobalt-free alternatives.
In 1938, John Livingood and Glenn T. Seaborg discovered the
radioisotope cobalt-60. This isotope was famously used at Columbia
University in the 1950s to establish parity violation in radioactive
beta decay.
After World War II, the US wanted to guarantee the supply of cobalt
ore for military uses (as the Germans had been doing) and prospected
for cobalt within the US. High purity cobalt was highly sought after
for its use in jet engines and gas turbines. An adequate supply of the
ore was found in Idaho near Blackbird canyon. Calera Mining Company
started production at the site.
Cobalt demand has further accelerated in the 21st century as an
essential constituent of materials used in rechargeable batteries,
superalloys, and catalysts. It has been argued that cobalt will be one
of the main objects of geopolitical competition in a world running on
renewable energy and dependent on batteries, but this perspective has
also been criticised for underestimating the power of economic
incentives for expanded production.
Occurrence
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The stable form of cobalt is produced in supernovae through the
r-process. It comprises 0.0029% of the Earth's crust. Except as
recently delivered in meteoric iron, free cobalt (the native metal) is
not found on Earth's surface because of its tendency to react with
oxygen in the atmosphere. Small amounts of cobalt compounds are found
in most rocks, soils, plants, and animals. In the ocean cobalt
typically reacts with chlorine.
In nature, cobalt is frequently associated with nickel. Both are
characteristic components of meteoric iron, though cobalt is much less
abundant in iron meteorites than nickel. As with nickel, cobalt in
meteoric iron alloys may have been well enough protected from oxygen
and moisture to remain as the free (but alloyed) metal.
Cobalt in compound form occurs in copper and nickel minerals. It is
the major metallic component that combines with sulfur and arsenic in
the sulfidic cobaltite (CoAsS), safflorite (CoAs2), glaucodot (), and
skutterudite (CoAs3) minerals. The mineral cattierite is similar to
pyrite and occurs together with vaesite in the copper deposits of
Katanga Province. When it reaches the atmosphere, weathering occurs;
the sulfide minerals oxidize and form pink erythrite ("cobalt glance":
Co3(AsO4)2·8H2O) and spherocobaltite (CoCO3).
Cobalt is also a constituent of tobacco smoke. The tobacco plant
readily absorbs and accumulates heavy metals like cobalt from the
surrounding soil in its leaves. These are subsequently inhaled during
tobacco smoking.
Production
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Cobalt mine production (2022) and reserves in tonnes according to USGS
Country data-sort-type="number" | Production data-sort-type="number"
| Reserves
| 130,000 4,000,000
| 10,000 600,000
| 8,900 250,000
| 5,900 1,500,000
| 3,900 220,000
| 3,800 500,000
| 3,800 260,000
| 3,000 100,000
| 3,000 47,000
| 2,700 36,000
| |2,300 |13,000
| |2,200 |140,000
| 800 69,000
Other countries 5,200 610,000
| **World total**
| **190,000**
| **8,300,000**
The main ores of cobalt are cobaltite, erythrite, glaucodot and
skutterudite (see above), but most cobalt is obtained by reducing the
cobalt by-products of nickel and copper mining and smelting.
Since cobalt is generally produced as a by-product, the supply of
cobalt depends to a great extent on the economic feasibility of copper
and nickel mining in a given market. Demand for cobalt was projected
to grow 6% in 2017.
Primary cobalt deposits are rare, such as those occurring in
hydrothermal deposits, associated with ultramafic rocks, typified by
the Bou-Azzer district of Morocco. At such locations, cobalt ores are
mined exclusively, albeit at a lower concentration, and thus require
more downstream processing for cobalt extraction.
Several methods exist to separate cobalt from copper and nickel,
depending on the concentration of cobalt and the exact composition of
the used ore. One method is froth flotation, in which surfactants bind
to ore components, leading to an enrichment of cobalt ores. Subsequent
roasting converts the ores to cobalt sulfate, and the copper and the
iron are oxidized to the oxide. Leaching with water extracts the
sulfate together with the arsenates. The residues are further leached
with sulfuric acid, yielding a solution of copper sulfate. Cobalt can
also be leached from the slag of copper smelting.
The products of the above-mentioned processes are transformed into the
cobalt oxide (Co3O4). This oxide is reduced to metal by the
aluminothermic reaction or reduction with carbon in a blast furnace.
Extraction
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The United States Geological Survey estimates world reserves of cobalt
at 11,000,000 metric tons.
The Democratic Republic of the Congo (DRC) currently produces 63% of
the world's cobalt. This market share may reach 73% by 2025 if planned
expansions by mining producers like Glencore Plc take place as
expected. Bloomberg New Energy Finance has estimated that by 2030,
global demand for cobalt could be 47 times more than it was in 2017.
Democratic Republic of the Congo
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Changes that Congo made to mining laws in 2002 attracted new
investments in Congolese copper and cobalt projects. In 2005, the top
producer of cobalt was the copper deposits in the Democratic Republic
of the Congo's Katanga Province. Formerly Shaba province, the area had
almost 40% of global reserves, reported the British Geological Survey
in 2009.
The Mukondo Mountain project, operated by the Central African Mining
and Exploration Company (CAMEC) in Katanga Province, may be the
richest cobalt reserve in the world. It produced an estimated
one-third of the total global cobalt production in 2008. In July 2009,
CAMEC announced a long-term agreement to deliver its entire annual
production of cobalt concentrate from Mukondo Mountain to Zhejiang
Galico Cobalt & Nickel Materials of China.
In 2016, Chinese ownership of cobalt production in the Congo was
estimated at over 10% of global cobalt supply, forming a key input to
the Chinese cobalt refining industry and granting China substantial
influence over the global cobalt supply chain. Chinese control of
Congolese cobalt has raised concern in Western nations which have
sought to reduce supply chain reliance upon China and have expressed
concern regarding labor and human rights violations in cobalt mines in
the DRC.
Glencore's Mutanda Mine shipped 24,500 tons of cobalt in 2016, 40% of
Congo DRC's output and nearly a quarter of global production. After
oversupply, Glencore closed Mutanda for two years in late 2019.
Glencore's Katanga Mining project is resuming as well and should
produce 300,000 tons of copper and 20,000 tons of cobalt by 2019,
according to Glencore.
In February 2018, global asset management firm AllianceBernstein
defined the DRC as economically "the Saudi Arabia of the electric
vehicle age", due to its cobalt resources, as essential to the
lithium-ion batteries that drive electric vehicles.
On 9 March 2018, President Joseph Kabila updated the 2002 mining code,
increasing royalty charges and declaring cobalt and coltan "strategic
metals". The 2002 mining code was effectively updated on 4 December
2018.
In February 2025, the DRC implemented a four-month suspension of
cobalt exports, citing an oversupply of the metal amid a price decline
to its lowest level in 21 years. Cobalt, a key byproduct of copper
mining, is an essential material in battery technology. The DRC
accounts for approximately 75 percent of the global supply. Within the
country, the China Molybdenum Company (CMOC) dominates the industry,
contributing roughly 40 percent of the world's cobalt production. Over
the past year, CMOC has significantly increased its output, doubling
production from two of its mines in the DRC from 56,000 tonnes to
114,000 tonnes.
Labor conditions
==================
Artisanal mining supplied 17% to 40% of the DRC production as of 2016.
Some 100,000 cobalt miners in Congo DRC use hand tools to dig hundreds
of feet, with little planning and fewer safety measures, say workers
and government and NGO officials, as well as 'The Washington Post'
reporters' observations on visits to isolated mines. The lack of
safety precautions frequently causes injuries or death. Mining
pollutes the vicinity and exposes local wildlife and indigenous
communities to toxic metals thought to cause birth defects and
breathing difficulties, according to health officials.
Child labor is used in mining cobalt from African artisanal mines.
Human rights activists have highlighted this and investigative
journalism reporting has confirmed it. This revelation prompted cell
phone maker Apple Inc., on 3 March 2017, to stop buying ore from
suppliers such as Zhejiang Huayou Cobalt who source from artisanal
mines in the DRC, and begin using only suppliers that are verified to
meet its workplace standards.
In 2023, Apple announced it would convert to using recycled cobalt by
2025.
There is a push globally by the EU and major car manufacturers (OEM)
for global production of cobalt to be sourced and -produced
sustainably, responsibly and traceability of the supply chain. Mining
companies are adopting and practising ESG initiatives in line with
OECD Guidance and putting in place evidence of zero to low carbon
footprint activities in the supply chain production of lithium-ion
batteries. These initiatives are already taking place with major
mining companies, artisanal and small-scale mining companies (ASM).
Car manufacturers and battery manufacturer supply chains: Tesla, VW,
BMW, BASF and Glencore are participating in several initiatives, such
as the Responsible Cobalt Initiative and Cobalt for Development study.
In 2018 BMW Group in partnership with BASF, Samsung SDI and Samsung
Electronics have launched a pilot project in the DRC over one pilot
mine, to improve conditions and address challenges for artisanal
miners and the surrounding communities.
The political and ethnic dynamics of the region have in the past
caused outbreaks of violence and years of armed conflict and displaced
populations. This instability affected the price of cobalt and also
created perverse incentives for the combatants in the First and Second
Congo Wars to prolong the fighting, since access to diamond mines and
other valuable resources helped to finance their military goals--which
frequently amounted to genocide--and also enriched the fighters
themselves. While DR Congo has in the 2010s not recently been invaded
by neighboring military forces, some of the richest mineral deposits
adjoin areas where Tutsis and Hutus still frequently clash, unrest
continues although on a smaller scale and refugees still flee
outbreaks of violence.
Cobalt extracted from small Congolese artisanal mining endeavors in
2007 supplied a single Chinese company, Congo DongFang International
Mining. A subsidiary of Zhejiang Huayou Cobalt, one of the world's
largest cobalt producers, Congo DongFang supplied cobalt to some of
the world's largest battery manufacturers, who produced batteries for
ubiquitous products like the Apple iPhones. Because of accused labour
violations and environmental concerns, LG Chem subsequently audited
Congo DongFang in accordance with OECD guidelines. LG Chem, which also
produces battery materials for car companies, imposed a code of
conduct on all suppliers that it inspects.
In December 2019, International Rights Advocates, a human rights NGO,
filed a landmark lawsuit against Apple, Tesla, Dell, Microsoft and
Google company Alphabet for "knowingly benefiting from and aiding and
abetting the cruel and brutal use of young children" in mining cobalt.
The companies in question denied their involvement in child labour. In
2024 the court ruled that the suppliers facilitate force labor but the
US tech companies are not liable because they don't operate as a
shared enterprise with the suppliers and that the "alleged injuries
are not fairly traceable" to any of the defendants' conduct. The book
'Cobalt Red' alleges that workers including children suffer injuries,
amputations, and death as the result of the hazardous working
conditions and mine tunnel collapses during artisanal mining of cobalt
in the DRC.
Since child and slave labor have been repeatedly reported in cobalt
mining, primarily in the artisanal mines of DR Congo, technology
companies seeking an ethical supply chain have faced shortages of this
raw material and the price of cobalt metal reached a nine-year high in
October 2017, more than US$30 a pound, versus US$10 in late 2015.
After oversupply, the price dropped to a more normal $15 in 2019. As a
reaction to the issues with artisanal cobalt mining in DR Congo a
number of cobalt suppliers and their customers have formed the Fair
Cobalt Alliance (FCA) which aims to end the use of child labor and to
improve the working conditions of cobalt mining and processing in the
DR Congo. Members of FCA include Zhejiang Huayou Cobalt, Sono Motors,
the Responsible Cobalt Initiative, Fairphone, Glencore and Tesla, Inc.
Canada
========
In 2017, some exploration companies were planning to survey old silver
and cobalt mines in the area of Cobalt, Ontario, where significant
deposits are believed to lie.
Cobalt mined in Canada is a by-product of nickel mining. Even so, in
2023 the country produced more than 5,000 tons of cobalt (43% is mined
in Newfoundland and Labrador, the rest in Ontario, Manitoba and
Quebec). Exports of cobalt and cobalt products totaled $568 million in
2023.
Cuba
======
Canada's Sherritt International processes cobalt ores in nickel
deposits from the Moa mines in Cuba, and the island has several others
mines in Mayarí, Camagüey, and Pinar del Río. Continued investments by
Sherritt International in Cuban nickel and cobalt production while
acquiring mining rights for 17-20 years made the communist country
third for cobalt reserves in 2019, before Canada itself.
Indonesia
===========
Starting from smaller amounts in 2021, Indonesia began producing
cobalt as a byproduct of nickel production. By 2022, the country had
become the world's second-largest cobalt producer, with Benchmark
Mineral Intelligence forecasting Indonesian output to make up 20
percent of global production by 2030. Cobalt production increased from
1,300 tons to 20,500 tons between 2015 and 2024 due to the Indonesian
government's strategic initiative to develop a robust domestic supply
chain for electric vehicles. An export ban in 2020 has ensured an
influx of foreign investment in nickel and cobalt processing in the
country.
Applications
======================================================================
In 2016, 116000 t of cobalt was used. Cobalt has been used in the
production of high-performance alloys. It is also used in some
rechargeable batteries.
Alloys
========
Cobalt-based superalloys have historically consumed most of the cobalt
produced. The temperature stability of these alloys makes them
suitable for turbine blades for gas turbines and aircraft jet engines,
although nickel-based single-crystal alloys surpass them in
performance. Cobalt-based alloys are also corrosion- and
wear-resistant, making them, like titanium, useful for making
orthopedic implants that do not wear down over time. The development
of wear-resistant cobalt alloys started in the first decade of the
20th century with the stellite alloys, containing chromium with
varying quantities of tungsten and carbon. Alloys with chromium and
tungsten carbides are very hard and wear-resistant. Special
cobalt-chromium-molybdenum alloys like Vitallium are used for
prosthetic parts (hip and knee replacements). Cobalt alloys are also
used for dental prosthetics as a useful substitute for nickel, which
may be allergenic. Some high-speed steels also contain cobalt for
increased heat and wear resistance. The special alloys of aluminium,
nickel, cobalt and iron, known as Alnico, and of samarium and cobalt
(samarium-cobalt magnet) are used in permanent magnets. It is also
alloyed with 95% platinum for jewelry, yielding an alloy suitable for
fine casting, which is also slightly magnetic.
In addition to structural and magnetic roles, cobalt alloys are
critical in aerospace-grade electrical components. They are used in
connectors, thermal switches, and microsensors that must endure
extreme temperatures, vibration, and radiation--conditions typical in
satellites, fighter aircraft, and hypersonic systems. These alloys
maintain conductivity and mechanical integrity even under fluctuating
mission-critical loads.
Batteries
===========
Lithium cobalt oxide (LiCoO2, aka "LCO"), first sold commercially in
1991 by Sony, was widely used in lithium-ion battery cathodes until
the 2010s. The material is composed of cobalt oxide layers with the
lithium intercalated. These LCO batteries continue to dominate the
market for consumer electronics. Batteries for electric cars however
have shifted to lower cobalt technologies.
In 2018 most cobalt in batteries was used in a mobile device, a more
recent application for cobalt is rechargeable batteries for electric
cars. This industry increased five-fold in its demand for cobalt from
2016 to 2020, which made it urgent to find new raw materials in more
stable areas of the world. Demand is expected to continue or increase
as the prevalence of electric vehicles increases. Exploration in
2016-2017 included the area around Cobalt, Ontario, an area where many
silver mines ceased operation decades ago. Cobalt for electric
vehicles increased 81% from the first half of 2018 to 7,200 tonnes in
the first half of 2019, for a battery capacity of 46.3 GWh.
As of August 2020 battery makers have gradually reduced the cathode
cobalt content from 1/3 (NMC 111) to 1/5 (NMC 442) to currently 1/10
(NMC 811) and have also introduced the cobalt free lithium iron
phosphate cathode into the battery packs of electric cars such as the
Tesla Model 3.
Research was also conducted by the European Union into the possibility
of eliminating cobalt requirements in lithium-ion battery production.
In September 2020, Tesla outlined their plans to make their own,
cobalt-free battery cells.
Nickel-cadmium (NiCd) and nickel metal hydride (NiMH) batteries also
included cobalt to improve the oxidation of nickel in the battery.
Lithium iron phosphate batteries officially surpassed ternary cobalt
batteries in 2021 with 52% of installed capacity. Analysts estimate
that its market share will exceed 60% in 2024.
Catalysts
===========
Several cobalt compounds are oxidation catalysts. Cobalt acetate is
used to convert xylene to terephthalic acid, the precursor of the bulk
polymer polyethylene terephthalate. Typical catalysts are the cobalt
carboxylates (known as cobalt soaps). They are also used in paints,
varnishes, and inks as "drying agents" through the oxidation of drying
oils. However, their use is being phased out due to toxicity concerns.
The same carboxylates are used to improve the adhesion between steel
and rubber in steel-belted radial tires. In addition they are used as
accelerators in polyester resin systems.
Cobalt-based catalysts are used in reactions involving carbon
monoxide. Cobalt is also a catalyst in the Fischer-Tropsch process for
the hydrogenation of carbon monoxide into liquid fuels.
Hydroformylation of alkenes often uses cobalt octacarbonyl as a
catalyst. The hydrodesulfurization of petroleum uses a catalyst
derived from cobalt and molybdenum. This process helps to clean
petroleum of sulfur impurities that interfere with the refining of
liquid fuels.
Pigments and coloring
=======================
Before the 19th century, cobalt was predominantly used as a pigment.
It has been used since the Middle Ages to make smalt, a blue-colored
glass. Smalt is produced by melting a mixture of roasted mineral
smaltite, quartz and potassium carbonate, which yields a dark blue
silicate glass, which is finely ground after the production. Smalt was
widely used to color glass and as pigment for paintings. In 1780, Sven
Rinman discovered cobalt green, and in 1802 Louis Jacques Thénard
discovered cobalt blue. Cobalt pigments such as cobalt blue (cobalt
aluminate), cerulean blue (cobalt(II) stannate), various hues of
cobalt green (a mixture of cobalt(II) oxide and zinc oxide), and
cobalt violet (cobalt phosphate) are used as artist's pigments because
of their superior chromatic stability.
Radioisotopes
===============
Cobalt-60 (Co-60 or 60Co) is useful as a gamma-ray source because it
can be produced in predictable amounts with high activity by
bombarding cobalt with neutrons. It produces gamma rays with energies
of 1.17 and 1.33 MeV.
Cobalt is used in external beam radiotherapy, sterilization of medical
supplies and medical waste, radiation treatment of foods for
sterilization (cold pasteurization), industrial radiography (e.g. weld
integrity radiographs), density measurements (e.g. concrete density
measurements), and tank fill height switches. The metal has the
unfortunate property of producing a fine dust, causing problems with
radiation protection. Cobalt from radiotherapy machines has been a
serious hazard when not discarded properly, and one of the worst
radiation contamination accidents in North America occurred in 1984,
when a discarded radiotherapy unit containing cobalt-60 was mistakenly
disassembled in a junkyard in Juarez, Mexico.
Cobalt-60 has a radioactive half-life of 5.27 years. Loss of potency
requires periodic replacement of the source in radiotherapy and is one
reason why cobalt machines have been largely replaced by linear
accelerators in modern radiation therapy. Cobalt-57 (Co-57 or 57Co) is
a cobalt radioisotope most often used in medical tests, as a
radiolabel for vitamin B uptake, and for the Schilling test. Cobalt-57
is used as a source in Mössbauer spectroscopy and is one of several
possible sources in X-ray fluorescence devices.
Nuclear weapon designs could intentionally incorporate 59Co, some of
which would be activated in a nuclear explosion to produce 60Co. The
60Co, dispersed as nuclear fallout, is sometimes called a cobalt bomb.
Magnetic materials
====================
Due to the ferromagnetic properties of cobalt, it is used in the
production of various magnetic materials. It is used in creating
permanent magnets like Alnico magnets, known for their strong magnetic
properties used in electric motors, sensors, and MRI machines. It is
also used in production of magnetic alloys like cobalt steel, widely
used in magnetic recording media such as hard disks and tapes.
Cobalt's ability to maintain magnetic properties at high temperatures
makes it valuable in magnetic recording applications, ensuring
reliable data storage devices. Cobalt also contributes to specialized
magnets such as samarium-cobalt and neodymium-iron-boron magnets,
which are vital in electronics for components like sensors and
actuators.
Other uses
============
* Cobalt is used in electroplating for its attractive appearance,
hardness, and resistance to oxidation.
* It is also used as a base primer coat for porcelain enamels.
Biological role
======================================================================
Cobalt is essential to the metabolism of all animals. It is a key
constituent of cobalamin, also known as vitamin B, the primary
biological reservoir of cobalt as an ultratrace element. Bacteria in
the stomachs of ruminant animals convert cobalt salts into vitamin B,
a compound which can only be produced by bacteria or archaea. A
minimal presence of cobalt in soils therefore markedly improves the
health of grazing animals, and an uptake of 0.20 mg/kg a day is
recommended, because they have no other source of vitamin B.
Proteins based on cobalamin use corrin to hold the cobalt. Coenzyme
B12 features a reactive C-Co bond that participates in the reactions.
In humans, B12 has two types of alkyl ligand: methyl and adenosyl.
MeB12 promotes methyl (−CH3) group transfers. The adenosyl version of
B12 catalyzes rearrangements in which a hydrogen atom is directly
transferred between two adjacent atoms with concomitant exchange of
the second substituent, X, which may be a carbon atom with
substituents, an oxygen atom of an alcohol, or an amine. Methylmalonyl
coenzyme A mutase (MUT) converts MMl-CoA to Su-CoA, an important step
in the extraction of energy from proteins and fats.
Although far less common than other metalloproteins (e.g. those of
zinc and iron), other cobaltoproteins are known besides B12. These
proteins include methionine aminopeptidase 2, an enzyme that occurs in
humans and other mammals that does not use the corrin ring of B12, but
binds cobalt directly. Another non-corrin cobalt enzyme is nitrile
hydratase, an enzyme in bacteria that metabolizes nitriles.
Cobalt deficiency
===================
In humans, consumption of cobalt-containing vitamin B12 meets all
needs for cobalt. For cattle and sheep, which meet vitamin B12 needs
via synthesis by resident bacteria in the rumen, there is a function
for inorganic cobalt. In the early 20th century, during the
development of farming on the North Island Volcanic Plateau of New
Zealand, cattle suffered from what was termed "bush sickness". It was
discovered that the volcanic soils lacked the cobalt salts essential
for the cattle food chain. The "coast disease" of sheep in the Ninety
Mile Desert of the Southeast of South Australia in the 1930s was found
to originate in nutritional deficiencies of trace elements cobalt and
copper. The cobalt deficiency was overcome by the development of
"cobalt bullets", dense pellets of cobalt oxide mixed with clay given
orally for lodging in the animal's rumen.
File:Cobalamin.svg |alt=chemical diagram of cobalamin
molecule|Cobalamin
File:CSIRO ScienceImage 10487 Cobalt deficient sheep.jpg |alt=two
cobalt-deficient sheep facing away from camera|Cobalt-deficient sheep
Health issues
======================================================================
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The LD50 value for soluble cobalt salts has been estimated to be
between 150 and 500 mg/kg. In the US, the Occupational Safety and
Health Administration (OSHA) has designated a permissible exposure
limit (PEL) in the workplace as a time-weighted average (TWA) of 0.1
mg/m3. The National Institute for Occupational Safety and Health
(NIOSH) has set a recommended exposure limit (REL) of 0.05 mg/m3,
time-weighted average. The IDLH (immediately dangerous to life and
health) value is 20 mg/m3.
However, chronic cobalt ingestion has caused serious health problems
at doses far less than the lethal dose. In 1966, the addition of
cobalt compounds to stabilize beer foam in Canada led to a peculiar
form of toxin-induced cardiomyopathy, which came to be known as 'beer
drinker's cardiomyopathy'.
Furthermore, cobalt metal is suspected of causing cancer (i.e.,
possibly carcinogenic, IARC Group 2B) as per the International Agency
for Research on Cancer (IARC) Monographs.
It causes respiratory problems when inhaled. It also causes skin
problems when touched; after nickel and chromium, cobalt is a major
cause of contact dermatitis.
References
======================================================================
{{Reflist|refs=
electronic-book electronic-.
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External links
======================================================================
*
* [
http://www.periodicvideos.com/videos/027.htm Cobalt] at 'The
Periodic Table of Videos' (University of Nottingham)
* [
https://www.cdc.gov/niosh/topics/cobalt/ Centers for Disease and
Prevention - Cobalt]
License
=========
All content on Gopherpedia comes from Wikipedia, and is licensed under CC-BY-SA
License URL:
http://creativecommons.org/licenses/by-sa/3.0/
Original Article:
http://en.wikipedia.org/wiki/Cobalt
