Cobalt is a chemical element; it has symbolCo 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.[9] 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, some cobalt is produced specifically from one of a number of metallic-lustered ores, such as cobaltite (CoAsS). The element is more usually produced as a by-product of copper and nickel mining. 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 tonnes (114,000 long tons; 128,000 short tons) (according to Natural Resources Canada), and the DRC alone accounted for more than 50%.[10]
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.[11]
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
A block of electrolytically refined cobalt (99.9% purity) cut from a large plate
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[Co(H 2O) 6]2+ in water. Addition of chloride gives the intensely blue [CoCl 4]2− .[7] In a borax bead flame test, cobalt shows deep blue in both oxidizing and reducing flames.[20]
The reduction potential for the reaction Co3+ + e− → Co2+ 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.[18]
Coordination compounds
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).[18]
Cobalt(II) forms a wide variety of complexes, but mainly with weakly basic ligands. The pink-colored cation hexaaquocobalt(II)[Co(H2O)6]2+ 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 CoCl2−4, which is tetrahedral.
Softer ligands like triphenylphosphine form complexes with Co(II) and Co(I), examples being bis- and tris(triphenylphosphine)cobalt(I) chloride, CoCl2(PPh3)2 and CoCl(PPh3)3. These Co(I) and Co(II) complexes represent a link to the organometallic complexes described below.
Cobaltocene is a structural analog to ferrocene, with cobalt in place of iron. Cobaltocene is much more sensitive to oxidation than ferrocene.[26] Cobalt carbonyl (Co2(CO)8) is a catalyst in carbonylation and hydrosilylation reactions.[27] Vitamin B12 (see below) is an organometallic compound found in nature and is the only vitamin that contains a metal atom.[28] 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,[29] in accord with Bredt's rule. The cobalt(III) and cobalt(V) complexes [Li(THF) 4]+ [Co(1-norb) 4]− and [Co(1-norb) 4]+ [BF 4]− are also known.[30]
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.[31]
The isotopes of cobalt range in atomic weight from 50 u (50Co) to 73 u (73Co). The primary decay mode for isotopes with atomic mass unit values 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 59 atomic mass units is beta decay. The primary decay products below 59Co are element 26 (iron) isotopes; above that the decay products are element 28 (nickel) isotopes.[31]
Many different stories about the origin of the word "cobalt" have been proposed. In one version the element cobalt was named after "kobelt", 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.[32][33] 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. § History below).[34]
The authority on such kobelt ore (Latinized as cobaltum or cadmia[35][36]) at the time was Georgius Agricola.[32][34] He was also the oft-quoted authority on the mine spirits called "kobel" (Latinized as cobalus or pl. cobali) in a separate work.[37][38][39]
Agricola did not make an connection between the similarly named ore and spirit. However, a causal connection (ore blamed on "kobel") was made by a contemporary,[41] and a word origin connection (word "formed" from cobalus) made by a late 18th century writer.[42] Later, Grimms' dictionary (1868) noted the kobalt/kobelt ore was blamed on the mountain spirit (Bergmännchen [de][b]) which was also held responsible for "stealing the silver and putting out an ore that caused poor mining atmosphere (Wetter[43]) and other health hazards".[33]
Grimms' dictionary entries equated the word "kobel" with "kobold", and listed it as a mere variant diminutive,[45] but the latter is defined in it as a household spirit.[44] Whereas some of the more recent commentators prefer to characterize the ore's namesake kobelt (recté kobel) as a gnome.[46][49]
The early 20th century Oxford English Dictionary (1st edition, 1908) had upheld Grimm's etymology.[c][50] 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.[51][52]
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.[53] 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.[54]
Joseph William Mellor (1935) also stated that cobalt may derive from kobalos (κόβαλος), though other theories had been suggested.[55]
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 Kübel, a bucket used in mining, frequently mentioned by Agricola,[51] namely the kobel/köbel (Latinized as modulus).[56]
Another theory given by the Etymologisches Wörterbuch derives the term from kōbathium[54] or rather cobathia (κωβάθια, "arsenic sulfide"[57]) which occurs as noxious fumes.[34]
W. W. Skeat and J. Berendes construed κόβαλος as "parasite", i.e. as an ore parasitic to nickel,[55] but this explanation is faulted for its anachronism since nickel was not discovered until 1751.[59][60]
History
Early Chinese blue and white porcelain, manufactured c. 1335
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).[61]
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.[62][63] 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.[64]
The word cobalt is derived from the 16th century German "kobelt", 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.[65]Paracelsus, Georgius Agricola, and Basil Valentine all referred to such silicates as "cobalt".[66]
Swedish chemist Georg Brandt (1694–1768) is credited with discovering cobalt c. 1735, showing it to be a previously unknown element, distinct from bismuth and other traditional metals. Brandt called it a new "semi-metal",[67][68] naming it for the mineral from which he had extracted it.[69]: 153 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.[70]
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.[71][72] 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.[65] When the Shaba conflict started in 1978, the copper mines of Katanga Province nearly stopped production.[73][74] 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.[73][74]
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.[78] An adequate supply of the ore was found in Idaho near Blackbird canyon. Calera Mining Company started production at the site.[79]
Cobalt demand has further accelerated in the 21st century as an essential constituent of materials used in rechargeable batteries, superalloys, and catalysts.[78] 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.[80]
Occurrence
The stable form of cobalt is produced in supernovae through the r-process.[81] 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.[82] 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.[83]
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.[92]
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.[93][94]
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.[95]
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.[18]
The United States Geological Survey estimates world reserves of cobalt at 7,100,000 metric tons.[96] 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.[97]
Changes that Congo made to mining laws in 2002 attracted new investments in Congolese copper and cobalt projects.[98] 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.[99]
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.[100] 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.[101]
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.[102] 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.[103][104]
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.[98][105] 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.[92]
On March 9, 2018, President Joseph Kabila updated the 2002 mining code, increasing royalty charges and declaring cobalt and coltan "strategic metals".[107][108] The 2002 mining code was effectively updated on December 4, 2018.[109]
Artisanal mining supplied 17% to 40% of the DRC production as of 2016.[110] 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.[111] 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.[112]
Child labor is used in mining cobalt from African artisanal mines.[110][113] Human rights activists have highlighted this and investigative journalism reporting has confirmed it.[114][115] This revelation prompted cell phone maker Apple Inc., on March 3, 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.[116][117] In 2023, Apple announced it would convert to using recycled cobalt by 2025.[118]
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[119] and Cobalt for Development[120] 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.[121]
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.[122]
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.[123] The companies in question denied their involvement in child labour.[124] 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.[125] The book Cobalt Red[126][127] 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.[128]
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.[129]
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.[130]
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.[131]
Applications
In 2016, 116,000 tonnes (128,000 short tons) of cobalt was used.[10] Cobalt has been used in the production of high-performance alloys.[90][91] It is also used in some rechargeable batteries.
Alloys
Cobalt-based superalloys have historically consumed most of the cobalt produced.[90][91] 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.[132] 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.[133] Special cobalt-chromium-molybdenum alloys like Vitallium are used for prosthetic parts (hip and knee replacements).[134] Cobalt alloys are also used for dental prosthetics as a useful substitute for nickel, which may be allergenic.[135] 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.[136] It is also alloyed with 95% platinum for jewelry, yielding an alloy suitable for fine casting, which is also slightly magnetic.[137]
Batteries
Lithium cobalt oxide (LiCoO2) is widely used in lithium-ion battery cathodes. The material is composed of cobalt oxide layers with the lithium intercalated. During discharge (i.e. when not actively being charged), the lithium is released as lithium ions.[138]Nickel–cadmium[139] (NiCd) and nickel metal hydride[140] (NiMH) batteries also include cobalt to improve the oxidation of nickel in the battery.[139] Transparency Market Research estimated the global lithium-ion battery market at $30 billion in 2015 and predicted an increase to over US$75 billion by 2024.[141]
Although in 2018 most cobalt in batteries was used in a mobile device,[142] a more recent application for cobalt is rechargeable batteries for electric cars. This industry has increased five-fold in its demand for cobalt, which makes it urgent to find new raw materials in more stable areas of the world.[143] Demand is expected to continue or increase as the prevalence of electric vehicles increases.[144] Exploration in 2016–2017 included the area around Cobalt, Ontario, an area where many silver mines ceased operation decades ago.[143] 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.[145][146]
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[147] 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.[148] After oversupply, the price dropped to a more normal $15 in 2019.[149][150] 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.[151][152]
Research is being conducted by the European Union into the possibility of eliminating cobalt requirements in lithium-ion battery production.[153][154] 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.[155][156] In September 2020, Tesla outlined their plans to make their own, cobalt-free battery cells.[157]
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.[158]
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.[159][138] However, their use is being phased out due to toxicity concerns.[160] 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.[161][162][163]
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.[166] Smalt was widely used to color glass and as pigment for paintings.[167] In 1780, Sven Rinman discovered cobalt green, and in 1802 Louis Jacques Thénard discovered cobalt blue.[168] 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.[169][170]
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.[31][171]
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.[175]Cobalt-57 (Co-57 or 57Co) is a cobalt radioisotope most often used in medical tests, as a radiolabel for vitamin B12 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.[176][177]
Due to the ferromagnetic properties of cobalt, it is used in the production of various magnetic materials.[180] It is used in creating permanent magnets like Alnico magnets, known for their strong magnetic properties used in electric motors, sensors, and MRI machines.[181][182] It is also used in production of magnetic alloys like cobalt steel, widely used in magnetic recording media such as hard disks and tapes.[183]
Cobalt's ability to maintain magnetic properties at high temperatures makes it valuable in magnetic recording applications, ensuring reliable data storage devices.[184] 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.[185]
Other uses
Cobalt is used in electroplating for its attractive appearance, hardness, and resistance to oxidation.[186]
Cobalt is essential to the metabolism of all animals. It is a key constituent of cobalamin, also known as vitamin B12, the primary biological reservoir of cobalt as an ultratrace element.[188][189]Bacteria in the stomachs of ruminant animals convert cobalt salts into vitamin B12, 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 B12.[190]
Proteins based on cobalamin use corrin to hold the cobalt. Coenzyme B12 features a reactive C-Co bond that participates in the reactions.[191] In humans, B12 has two types of alkylligand: 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.[192]
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.[193]
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.[194][195] 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.[clarification needed][196][195][197]
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.[201][202]
It causes respiratory problems when inhaled.[204] It also causes skin problems when touched; after nickel and chromium, cobalt is a major cause of contact dermatitis.[205]
Notes
^The thermal expansion of cobalt is anisotropic: the coefficients for each crystal axis are (at 20 °C): αa = 10.9×10−6/K, αc = 17.9×10−6/K, and αaverage = αV/3 = 12.9×10−6/K.
^Grimm's dictionary more specifically calls it "spectral mountain manikin" (gespenstisches Bergmännchen), elsewhere ("Kobold" II) it is notes kobold also refers to Berggeist in bergmännisch (miners' lingo).
^Grimm derived and kobold from Greek kobalos, as aforestated; the OED concurred that kobold, kobelt (ore), kobel (mine spirit) were the same word.
^ abArblaster, John W. (2018). Selected Values of the Crystallographic Properties of Elements. Materials Park, Ohio: ASM International. ISBN978-1-62708-155-9.
^Co(–3) is known in Na3Co(CO)3; see John E. Ellis (2006). "Adventures with Substances Containing Metals in Negative Oxidation States". Inorganic Chemistry. 45 (8). doi:10.1021/ic052110i.
^Lee, B.; Alsenz, R.; Ignatiev, A.; Van Hove, M.; Van Hove, M. A. (1978). "Surface structures of the two allotropic phases of cobalt". Physical Review B. 17 (4): 1510–1520. Bibcode:1978PhRvB..17.1510L. doi:10.1103/PhysRevB.17.1510.
^Cobalt. Brussels: Centre d'Information du Cobalt. 1966. p. 45.
^ abcdeHolleman, A. F.; Wiberg, E.; Wiberg, N. (2007). "Cobalt". Lehrbuch der Anorganischen Chemie (in German) (102nd ed.). de Gruyter. pp. 1146–1152. ISBN978-3-11-017770-1.
^Housecroft, C. E.; Sharpe, A. G. (2008). Inorganic Chemistry (3rd ed.). Prentice Hall. p. 722. ISBN978-0-13-175553-6.
^Krebs, Robert E. (2006). The history and use of our earth's chemical elements: a reference guide (2nd ed.). Greenwood Publishing Group. p. 107. ISBN0-313-33438-2.
^Byrne, Erin K.; Richeson, Darrin S.; Theopold, Klaus H. (January 1, 1986). "Tetrakis(1-norbornyl)cobalt, a low spin tetrahedral complex of a first row transition metal". Journal of the Chemical Society, Chemical Communications (19): 1491. doi:10.1039/C39860001491. ISSN0022-4936.
^Byrne, Erin K.; Theopold, Klaus H. (February 1, 1987). "Redox chemistry of tetrakis(1-norbornyl)cobalt. Synthesis and characterization of a cobalt(V) alkyl and self-exchange rate of a Co(III)/Co(IV) couple". Journal of the American Chemical Society. 109 (4): 1282–1283. doi:10.1021/ja00238a066. ISSN0002-7863.
^Agricola, Georgius (1546) [1530]. "Bermannus, sive de re metallica dialogus". Georgii Agricolae De ortu & causis subterraneorum lib. 5. De natura eorum quae effluunt ex terra lib. 4. De natura fossilium lib. 10. De ueteribus & nouis metallis lib. 2. Bermannus, siue De re metallica dialogus lib.1. Interpretatio Germanica uocum rei metallicæ, addito Indice fœcundissimo. Basel: Froben. pp. 441–442. cobaltum nostri uocant, Græci cadmiam; Cf. index under "cobaltum".
^Agricola, Georgius (1614) [1549]. "37". In Johannes Sigfridus (ed.). Georgii Agricolae De Animantibus subterraneis. Witebergæ: Typis Meisnerianis. pp. 78–79.
^ abAgricola, Georgius (1657) [1530]. "Animantium nomina latina, graega, q'ue germanice reddita, quorum author in Libro de subterraneis animantibus meminit". Georgii Agricolae Kempnicensis Medici Ac Philosophi Clariss. De Re Metallica Libri XII.: Quibus Officia, Instrumenta, Machinae, Ac Omnia Denique Ad Metallicam Spectantia, Non Modo Luculentissime describuntur; sed & per effigies, suis locis insertas ... ita ob oculos ponuntur, ut clarius tradi non possint. Basel: Sumptibus & Typis Emanuelis König. p. [762]. Dæmonum: Dæmon subterraneus trunculentus: bergterufel; mitis bergmenlein/kobel/guttel
^This passage from the separate work, de animantibus is translated in footnote by the Agricola & Hoovers trr. (1912), p. 217, n26: "the Germans as well as the Greeks call cobalos".
^Lutheran reformist theologian Johannes Mathesius's sermon (1652) on the nuisance kobelt ore believed caused by a demon known to the masses as kobel. Quoted in English by the Hoovers,[40] excerpted by Wothers.[34]
^Johann Beckmann (Eng. tr. 1797), who did explicitly comment on the derivation of the word for "cobalt" ore as formed from kobel (Agricola's cobalus) has been cited by chemist Peter Wothers on this topic.[34]
^"New and complete dictionary of the German language for Englishmen" s.v. "Das Wetter": "4. Air and vapours, damps, steams... among Miners", Küttner, Carl Gottlob; Nicholson, William, edd. (1813), vol. 3.
^Grimms dictionary states that kobalt and kobold are "the same word at its original source (ursprünglich)".[33] Also, Grimm's entry in "kobold", III. ursprung, nebenformen, 3) a) lists kobel as a diminutive Nebenname.[44]
^The kobel was aka "bergmenlin" (mod. standard spelling Bergmännlein, Bergmännchen) according to Agricola's gloss.[38] Grimms dictionary also says the ores are caused by Bergmännchen sprites, but it thinks the miners call this "kobold", not distinguishable from "kobel". Whereas Lecouteux's dictionary defines "Bergmännchen" as "mine spirit" and admits "kobel" but not "kobld" as synonym.[47] More recently, literature is found that does not hesitate to call the Bergmännchen a "gnome".[48]
^ abMüller-Fraureuth, Karl (1906). "Kap. 14". Sächsische Volkswörter: Beiträge zur mundartlichen Volkskunde. Dresden: Wilhelm Baensch. pp. 25–26. ISBN978-3-95770-329-3.
^Glasenapp, Carl Friedrich[in German] (1911). "III. Der Kobold". Siegfried Wagner und seine Kunst: gesammelte Aufsätze über das dramatische Schaffen Siegfried Wagners vom "Bärenhäuter" bis zum "Banadietrich". Illustrated by Franz Stassen. Leipzig: Breitkopf & Härtel. p. 134.
^Liddell and Scott (1940). A Greek–English Lexicon. s.v. "kwba/qia". Revised and augmented throughout by Sir Henry Stuart Jones with the assistance of Roderick McKenzie. Oxford: Clarendon Press. ISBN0-19-864226-1. Online version retrieved 29 August 2024.
^Merck, Emanuel (1902). "Cobaltum metall". Airy Nothings: Imagining the Otherworld of Faerie from the Middle Ages to the Age of Reason: Essays in Honour of Alasdair A. MacDonald (2 ed.). Darmstadt: E. Merck. p. 75.
^Pulak, Cemal (1998). "The Uluburun shipwreck: an overview". International Journal of Nautical Archaeology. 27 (3): 188–224. doi:10.1111/j.1095-9270.1998.tb00803.x.
^Georg Brandt first showed cobalt to be a new metal in: G. Brandt (1735) "Dissertatio de semimetallis" (Dissertation on semi-metals), Acta Literaria et Scientiarum Sveciae (Journal of Swedish literature and sciences), vol. 4, pages 1–10. 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) "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.
^ abWesting, Arthur H; Stockholm International Peace Research Institute (1986). "cobalt". Global resources and international conflict: environmental factors in strategic policy and action. Oxford University Press. pp. 75–78. ISBN978-0-19-829104-6.
^Wróblewski, A. K. (2008). "The Downfall of Parity – the Revolution That Happened Fifty Years Ago". Acta Physica Polonica B. 39 (2): 251. Bibcode:2008AcPPB..39..251W. S2CID34854662.
^Ptitsyn, D. A.; Chechetkin, V. M. (1980). "Creation of the Iron-Group Elements in a Supernova Explosion". Soviet Astronomy Letters. 6: 61–64. Bibcode:1980SvAL....6...61P.
^Kara, Siddharth (2023). Cobalt red: how the blood of the Congo powers our lives (First ed.). New York, NY: St. Martin's Press. ISBN978-1-250-28429-7.
^Aikins, Matthieu. "How Is Your Phone Powered? Problematically". The New York Times. Retrieved November 9, 2024. Siddharth Kara's "Cobalt Red" takes a deep dive into the horrors of mining the valuable mineral – and the many who benefit from others' suffering.
^Michel, R.; Nolte, M.; Reich M.; Löer, F. (1991). "Systemic effects of implanted prostheses made of cobalt-chromium alloys". Archives of Orthopaedic and Trauma Surgery. 110 (2): 61–74. doi:10.1007/BF00393876. PMID2015136. S2CID28903564.
^Luborsky, F. E.; Mendelsohn, L. I.; Paine, T. O. (1957). "Reproducing the Properties of Alnico Permanent Magnet Alloys with Elongated Single-Domain Cobalt-Iron Particles". Journal of Applied Physics. 28 (344): 344. Bibcode:1957JAP....28..344L. doi:10.1063/1.1722744.
^ abArmstrong, R. D.; Briggs, G. W. D.; Charles, E. A. (1988). "Some effects of the addition of cobalt to the nickel hydroxide electrode". Journal of Applied Electrochemistry. 18 (2): 215–219. doi:10.1007/BF01009266. S2CID97073898.
^Zhang, P.; Yokoyama, Toshiro; Itabashi, Osamu; Wakui, Yoshito; Suzuki, Toshishige M.; Inoue, Katsutoshi (1999). "Recovery of metal values from spent nickel–metal hydride rechargeable batteries". Journal of Power Sources. 77 (2): 116–122. Bibcode:1999JPS....77..116Z. doi:10.1016/S0378-7753(98)00182-7.
^Weatherhead, R. G. (1980), Weatherhead, R. G. (ed.), "Catalysts, Accelerators and Inhibitors for Unsaturated Polyester Resins", FRP Technology: Fibre Reinforced Resin Systems, Dordrecht: Springer Netherlands, pp. 204–239, doi:10.1007/978-94-009-8721-0_10, ISBN978-94-009-8721-0
^Khodakov, Andrei Y. Khodakov; Chu, Wei & Fongarland, Pascal (2007). "Advances in the Development of Novel Cobalt Fischer-Tropsch Catalysts for Synthesis of Long-Chain Hydrocarbons and Clean Fuels". Chemical Reviews. 107 (5): 1692–1744. doi:10.1021/cr050972v. PMID17488058.
^Hebrard, Frédéric & Kalck, Philippe (2009). "Cobalt-Catalyzed Hydroformylation of Alkenes: Generation and Recycling of the Carbonyl Species, and Catalytic Cycle". Chemical Reviews. 109 (9): 4272–4282. doi:10.1021/cr8002533. PMID19572688.
^Mandeville, C.; Fulbright, H. (1943). "The Energies of the γ-Rays from Sb122, Cd115, Ir192, Mn54, Zn65, and Co60". Physical Review. 64 (9–10): 265–267. Bibcode:1943PhRv...64..265M. doi:10.1103/PhysRev.64.265.
^Mohapatra, Jeotikanta; Xing, Meiying (2020). "Hard and semi-hard magnetic materials based on cobalt and cobalt alloys". Journal of Alloys and Compounds. 824. doi:10.1016/j.jallcom.2020.153874.
^Davis, Joseph R; Handbook Committee, ASM International (May 1, 2000). "Cobalt". Nickel, cobalt, and their alloys. ASM International. p. 354. ISBN978-0-87170-685-0.
^Committee on Technological Alternatives For Cobalt Conservation, National Research Council (U.S.); National Materials Advisory Board, National Research Council (U.S.) (1983). "Ground–Coat Frit". Cobalt conservation through technological alternatives. p. 129.
^Yamada, Kazuhiro (2013). "Chapter 9. Cobalt: Its Role in Health and Disease". In Sigel, Astrid; Sigel, Helmut; Sigel, Roland K. O. (eds.). Interrelations between Essential Metal Ions and Human Diseases. Metal Ions in Life Sciences. Vol. 13. Springer. pp. 295–320. doi:10.1007/978-94-007-7500-8_9. ISBN978-94-007-7499-5. PMID24470095.
^Schwarz, F. J.; Kirchgessner, M.; Stangl, G. I. (2000). "Cobalt requirement of beef cattle – feed intake and growth at different levels of cobalt supply". Journal of Animal Physiology and Animal Nutrition. 83 (3): 121–131. doi:10.1046/j.1439-0396.2000.00258.x.
^Smith, David M.; Golding, Bernard T.; Radom, Leo (1999). "Understanding the Mechanism of B12-Dependent Methylmalonyl-CoA Mutase: Partial Proton Transfer in Action". Journal of the American Chemical Society. 121 (40): 9388–9399. doi:10.1021/ja991649a.
^"Cobalt 356891". Sigma-Aldrich. October 14, 2021. Retrieved December 22, 2021.
^Donaldson, John D. and Beyersmann, Detmar (2005) "Cobalt and Cobalt Compounds" in Ullmann's Encyclopedia of Industrial Chemistry, Wiley-VCH, Weinheim. doi:10.1002/14356007.a07_281.pub2
Jefferson, J. A.; Escudero, E.; Hurtado, M. E.; Pando, J.; Tapia, R.; Swenson, E. R.; Prchal, J.; Schreiner, G. F.; Schoene, R. B.; Hurtado, A.; Johnson, R. J. (2002). "Excessive erythrocytosis, chronic mountain sickness, and serum cobalt levels". Lancet. 359 (9304): 407–8. doi:10.1016/s0140-6736(02)07594-3. PMID11844517. S2CID12319751.
Løvold, T. V.; Haugsbø, L. (1999). "Cobalt mining factory--diagnoses 1822-32". Tidsskrift for den Norske Laegeforening. 119 (30): 4544–6. PMID10827501.
Bird, G. A.; Hesslein, R. H.; Mills, K. H.; Schwartz, W. J.; Turner, M. A. (1998). "Bioaccumulation of radionuclides in fertilized Canadian Shield lake basins". The Science of the Total Environment. 218 (1): 67–83. Bibcode:1998ScTEn.218...67B. doi:10.1016/s0048-9697(98)00179-x. PMID9718743.
Kerfoot, E. J.; Fredrick, W. G.; Domeier, E. (1975). "Cobalt metal inhalation studies on miniature swine". American Industrial Hygiene Association Journal. 36 (1): 17–25. doi:10.1080/0002889758507202. PMID1111264.
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