Preparations containing cobalt

Indications for the appointment of a macroelement are preventive and restorative. Doctors practice prescribing drugs for diseases of the joints, painful menstruation, menopause, memory impairment, stomach ulcers, varicose veins, and convulsions.

As a rule, cobalt preparations are prescribed for anemia and hematopoietic disorders. These dosage forms include:

  • Koamid;
  • Ferkoven.

Cobalt is also included in the composition of multivitamin complexes:

  • Compliment. Contains 100 micrograms of cobalt as sulfate.
  • Oligovite. Contains 50 mcg of the element as cobalt sulfate.

Taking drugs containing cobalt, as well as vitamin and mineral complexes, should be carried out only on the recommendation of the attending physician.

Cobalt coamide (Coamidum)- a complex preparation of cobalt and nicotinic acid amide. It is produced in the form of a powder of lilac color, odorless with a bitter taste.

The drug dissolves in water in a ratio of 1:10. Poorly soluble in organic solvents. Aqueous solutions are sterilized by conventional methods.

The drug is prescribed to stimulate hematopoiesis, the absorption of iron and the processes of its transformation (formation of protein complexes, hemoglobin synthesis, etc.).

Indications: hypochromic anemia, Addison-Birmer anemia (pernicious anemia malignant), anemia with sprue. With iron deficiency anemia, iron preparations are prescribed simultaneously. The drug is injected under the skin in the form of a 1% aqueous solution of 1 ml daily.

The duration of treatment depends on the course of the disease and the results. Average duration treatment - 3-4 weeks.

Ferkoven (Fercovenum). Release form - 5 ml ampoules. Transparent liquid of reddish-brown color, sweetish taste; pH 11.0-12.0.

Active ingredients: iron saccharate, cobalt gluconate.

Pharmacological action - a stimulant of hematopoiesis.

Ingredients: cobalt gluconate and carbohydrate solution. The content of iron in 1 ml is about 0.02 g, cobalt - 0.00009 g.

Indications for use:

  • hypochromic anemia (decreased hemoglobin content in the blood);
  • poor tolerance and insufficient absorption of iron preparations;
  • elimination of iron deficiency.

Mode of application. Intravenously once a day. Apply daily for 10-15 days: the first two injections - 2 ml, then - 5 ml. Enter slowly (within 8-10 minutes). Avoid contact of the solution with the skin.

Apply only in a hospital (hospital).

In case of iron deficiency, the dosage of the drug is calculated according to the formula. Iron deficiency in mg is equal to: the patient's weight in kg × 2.5 ×.

To maintain the effect achieved by the introduction of Ferkoven, iron preparations are used orally.

Side effects. With the first injections into the vein of Ferkoven and with an overdose of the drug, the following are possible:

  • hyperemia (redness) of the face, neck;
  • feeling of constriction in the chest;
  • lower back pain.

Side effects are eliminated with the help of an anesthetic (injected under the skin) 0.5 ml of a 0.1% solution of Atropine.

Contraindications:

  • hemochromatosis (impaired metabolism of iron-containing pigments);
  • liver disease;
  • coronary insufficiency (a discrepancy between the heart's need for oxygen and its delivery);
  • hypertension stage II-III (persistent increase in blood pressure).

Compliment. Vitamin-mineral complex, compensates for the deficiency of vitamins and minerals.

Release form - 365 tablets for vitamin and mineral support throughout the year.

The composition includes 11 vitamins and 8 minerals. Of them:

  • ascorbic acid, folic acid, riboflavin;
  • tocopherol acetate (alpha form), calcium pantothenate;
  • thioctic acid, rutoside, nicotinic acid;
  • copper, nicotinamide, cyanocobalamin, pyridoxine;
  • zinc, thiamine, cobalt, iron, calcium, manganese, magnesium.

Additional components:

  • magnesium carbonate, starch, methylcellulose;
  • talc, titanium dioxide pigment, flour;
  • wax, calcium stearate, povidone, sucrose, gelatin.

Release form: biconvex tablets white with a specific smell.

Indications for use:

  • prevention and replenishment of deficiency of vitamins and minerals;
  • increased physical and mental stress;
  • the period of recovery after prolonged and / or severe diseases, including infectious ones;
  • complex treatment with antibiotic therapy.

Oligovite. Indications for use:

  • prevention and treatment of hypo- and avitaminosis and mineral deficiency in case of inadequate and unbalanced nutrition;
  • the period of recovery after past illnesses, increased physical and mental stress, during intensive sports.

Contraindications:

  • hypersensitivity to the components of the drug;
  • pregnancy and breastfeeding period;
  • hypervitaminosis A, E, D;
  • thyrotoxicosis, decompensated heart failure;
  • peptic ulcer of the stomach and duodenum in the acute stage;
  • high calcium levels (hypercalcemia).

Cobalt is a hard metal that exists in two modifications. At temperatures from room temperature to 427 °C, the b-modification is stable. At temperatures from 427 °C to the melting point (1494 °C), the β-modification of cobalt is stable (face-centered cubic lattice). Cobalt is a ferromagnetic, Curie point 1121 °C.

It is a shiny iron-like metal with a specific gravity of 8.8. Its melting point is slightly higher than that of nickel. Cobalt is very malleable. It has greater hardness and strength than steel. It is ferromagnetic and only above 10,000 goes into a modification that does not have the ability to be magnetized.

A thin layer of oxides gives it a yellowish tint.

At ordinary temperature and up to 417 °C, the crystal lattice of Cobalt is hexagonal close-packed (with periods a = 2.5017E, c = 4.614E), above this temperature the Cobalt lattice is face-centered cubic (a = 3.5370E). Atomic radius 1.25E, ionic radii Co 2+ 0.78E and Co 3+ 0.64E. Density 8.9 g / cm 3 (at 20 ° C); t pl 1493°C, t bp 3100°C. Heat capacity 0.44 kJ/(kg K), or 0.1056 cal/(g °C); thermal conductivity 69.08 W / (m K), or 165 cal / (cm sec ° C) at 0-100 ° C. Electrical resistivity 5.68 10 -8 ohm m, or 5.68 10 -6 ohm cm (at 0 °C). Cobalt is ferromagnetic, and retains ferromagnetism from low temperatures to the Curie point, U = 1121 °C. The mechanical properties of Cobalt depend on the method of mechanical and thermal processing. Tensile strength 500 MN / m 2 (or 50 kgf / mm 2) for forged and annealed Cobalt; 242-260 MN/m 2 for cast; 700 MN/m 2 for wire. Brinell hardness 2.8 Gn / m 2 (or 280 kgf / mm 2) for work-hardened metal, 3.0 Gn / m 2 for electrolysis deposited; 1.2-1.3 Gn / m 2 for annealed.

Chemical properties of cobalt

The configuration of the outer electron shells of the Cobalt atom is 3d 7 4s 2 . In compounds, Cobalt exhibits a variable valence. In simple compounds, Co(II) is the most stable; in complex compounds, Co(III). For Co(I) and Co(IV), only a few complex compounds have been obtained. At ordinary temperatures compact Cobalt is resistant to water and air. Finely crushed Cobalt, obtained by reduction of its oxide with hydrogen at 250 °C (pyrophoric Cobalt), ignites spontaneously in air, turning into CoO. Compact Cobalt begins to oxidize in air above 300°C; at red heat, it decomposes water vapor: Co + H 2 O \u003d CoO + H 2. Cobalt easily combines with halogens when heated, forming COX 2 halides. When heated, Cobalt interacts with S, Se, P, As, Sb, C, Si, B, and the composition of the resulting compounds sometimes does not satisfy the above valence states (for example, Co 2 P, Co 2 As, CoSb 2, Co 3 C, CoSi 3). In dilute hydrochloric and sulfuric acids, Cobalt slowly dissolves with the release of hydrogen and the formation of CoCl 2 chloride and CoSO 4 sulfate, respectively. Dilute nitric acid dissolves Cobalt with the release of nitrogen oxides and the formation of nitrate Co(NO 3) 2 . Concentrated HNO 3 passivates Cobalt. These Co(II) salts are highly soluble in water [at 25°C, 100 g of water dissolve 52.4 g of CoCl 2 , 39.3 g of CoSO 4 , 136.4 g of Co(NO 3) 2 ]. Caustic alkalis precipitate blue hydroxide Co (OH) 2 from solutions of Co 2+ salts, which gradually turns brown due to oxidation by atmospheric oxygen to Co (OH) 3. Heating in oxygen at 400-500 ° C converts CoO into black oxide-oxide Co 3 O 4, or CoO · Co 2 O 3 - a spinel-type compound. A compound of the same type CoAl 2 O 4 or CoO Al 2 O 3 blue (thenar blue, discovered in 1804 by L. J. Tenard) is obtained by calcining a mixture of CoO and Al 2 O 3 at a temperature of about 1000 ° C

Of the simple Co(III) compounds, only a few are known. Under the action of fluorine on powder Co or CoCl 2 at 300-400 ° C, brown fluoride CoF 3 is formed. Complex compounds of Co (III) are very stable and easily obtained. For example, KNO 2 precipitates yellow sparingly soluble potassium hexanitrocobaltate (III) K 3 from solutions of Co (II) salts containing CH 3 COOH. Cobaltammines (the former name of cobaltiacs) are very numerous - complex compounds of Co (III) containing ammonia or some organic amines.

Water and air at ordinary temperatures have no effect on compact cobalt, but in a finely divided state it has pyrophoric properties. In dilute acids, such as hydrochloric or sulfuric, cobalt dissolves much more difficult, which corresponds to its position in the electrochemical series of voltages to the right of iron (its normal potential is -0.28 V). Dilute nitric acid readily dissolves cobalt, while it is passivated by the action of concentrated HNO3. It forms compounds most often in the +2 oxidation state, less often in the +3 oxidation state, and very rarely in the +1, +4 and +5 oxidation states.

When heated in air, Co oxidizes, and at white heat it burns to Co 3 O 4 . When heated, cobalt combines with many other substances, and its reaction with S, P, As, Sb, Sn and Zn is often accompanied by ignition. When fused with silicon, Co forms a variety of compounds. At high temperatures, it also combines with boron, but does not react with nitrogen. Cobalt readily forms compounds with halogens. With iron and nickel, as well as with chromium and manganese, it forms solid solutions in any ratio. In relation to carbon, cobalt behaves in the same way as iron; however, when carbonaceous melts are cooled, carbide Co 3 C is never released (although, according to Ruff, its existence in the melt is probable); if the carbon content exceeds the limits of solid solution existence, the excess carbon is always precipitated as graphite. Under the action of CH4 or CO on finely ground metallic cobalt at low heating (below 225°), according to Bar, the compound Co2C is formed, which decomposes at more high temperatures. The catalytic decomposition of CH 4 and CO under the action of cobalt occurs only at such temperatures when the carbide becomes unstable

Co + 2HCl (razb.) + t \u003d CoCl 2 + H 2

Co + H 2 SO 4 (razb.) + t \u003d CoSO 4 + H 2

3Co + 8HNO 4 (razb.) + t \u003d 3Co (NO 3) 2 + 2NO + 4H 2 O

4Co + 4NaOH + 3O 2 +t= 4NaCoO2 + 2H 2 O

2Co + O2 +t=2CoO

Receipt

Cobalt is a relatively rare metal, and the deposits rich in it are now practically exhausted. Therefore, cobalt-containing raw materials (often these are nickel ores containing cobalt as an impurity) are first enriched, and a concentrate is obtained from it.

This alloy is then leached with sulfuric acid. Sometimes, to extract cobalt, sulfuric acid "heap" leaching of the original ore is carried out (crushed ore is placed in high heaps on special concrete platforms and these heaps are poured with a leaching solution from above).

Extraction is increasingly being used to purify cobalt from accompanying impurities.

The most difficult task in the purification of cobalt from impurities is the separation of cobalt from the cobalt closest to it. chemical properties nickel.

2CoCl 2 + NaClO + 4NaOH + H 2 O \u003d 2Co (OH) 3 v + 5NaCl

The black precipitate Co(OH) 3 is calcined to remove water, and the resulting oxide Co 3 O 4 is reduced with hydrogen or carbon. Metallic cobalt containing up to 2-3% impurities (nickel, iron, copper) can be purified by electrolysis.

Formation of cobalt compounds

· When heated, cobalt reacts with halogens, and cobalt (III) compounds are formed only with fluorine. 2Co + 3F 2 > CoF 3, but, Co + Cl 2 > CoCl 2

· With sulfur, cobalt forms 2 different modifications of CoS. Silver-gray b-form (when powders are fused) and black b-form (precipitates from solutions).

When CoS is heated in an atmosphere of hydrogen sulfide, complex sulfide Co 9 S 8 is obtained

· With other oxidizing elements such as carbon, phosphorus, nitrogen, selenium, silicon, boron. cobalt also forms complex connections, which are mixtures where cobalt is present with oxidation states 1, 2, 3.

Cobalt is able to dissolve hydrogen without forming chemical compounds. Two stoichiometric cobalt hydrides CoH 2 and CoH were synthesized indirectly.

· Solutions of cobalt salts CoSO 4 , CoCl 2 , Co (NO 3) 2 give the water a pale pink color. Solutions of cobalt salts in alcohols are dark blue. Many cobalt salts are insoluble.

· Cobalt creates complex compounds. Most often based on ammonia.

The most stable complexes are yellow luteosalts 3+.

History of cobalt

Many legends and legends are connected with the history of the discovery of cobalt. In the Middle Ages, people were sure that it could not have done without the intervention of evil spirits. After all, no wonder the name cobalt comes from German Kobolt - a malicious dwarf, a little dwarf who built all sorts of intrigues, preventing the miners of Saxony from mining and smelting metal. Some of the ores mined in Saxony were silver in color and were at first thought to be silver. But the metal obtained from these ores gave off poisonous fumes, with which the miners (calorizator) were repeatedly poisoned. In 1735, the Swedish chemist Georg Brandt isolated a silvery-pinkish metal from the "ore of evil spirits", which was named kobold Subsequently, the name was transformed into a well-known and familiar to us.

Cobalt is an element of the IX group of the IV period of the periodic system chemical elements DI. Mendeleev, with atomic number 27 and atomic mass 58.9332. The recognized designation for cobalt is co(from the Latin Cobaltum).

Being in nature

Cobalt is not a very common metal, rather it can be classified as rare, it is present in the earth's crust in minimal quantities. There are no more than 30 minerals, which contain cobalt. The largest cobalt deposit is located in the Democratic Republic of the Congo, there are deposits in the USA, France, Canada and Russia.

Physical and chemical properties

Cobalt is a silvery-white hard metal with a slightly pinkish (rarely blue) tint. When interacting with air, oxidation occurs at high temperatures (300˚С and above).

Daily requirement for cobalt

The daily requirement for cobalt is very small, usually 0.1 - 0.8 mg for a healthy adult. Usually, a person receives the daily norm of cobalt from food.

Main sources of cobalt:

  • and oily fish
  • , green leafy vegetables
  • , some types of bread
  • , cheeses.


Signs of Cobalt Deficiency

Signs of a lack of cobalt in the human body are more frequent diseases of the circulatory and endocrine systems. The cause of cobalt deficiency is usually chronic diseases of the digestive system (gastritis, duodenal ulcer).

The use of cobalt in life

Cobalt has found wide application in the form of alloys - in the metallurgical industry to increase the heat resistance of steel, in the production of magnets, as a composition of dyes - in the manufacture of glass and ceramics.

Cobalt is one of the vital trace elements, its presence in the human body is mandatory. Cobalt is part of, takes part in the synthesis of DNA and amino acids, in the breakdown of proteins, fats and carbohydrates. Actively affects the metabolic processes of the body, plays a special role in hematopoiesis - stimulates the growth and development of red blood cells. Cobalt supports the normal activity of the pancreas and the regulation of adrenaline activity.

Cobalt(lat. Cobaltum), Co, a chemical element of the first triad of group VIII of Mendeleev's periodic system; atomic number 27, atomic mass 58.9332; heavy metal of silver color with a pinkish tint. In nature, the element is represented by one stable isotope 59 Co; of the artificially obtained radioactive isotopes, the most important is 60 Co.

Historical reference. Cobalt oxide was used in ancient Egypt, Babylon, and China to color glass and enamel blue. For the same purpose, in the 16th century in Western Europe they began to use cafra, or safflower, a gray earthy mass, which was obtained by roasting certain ores called "kobold". These ores emitted abundant poisonous smoke during roasting, and it was not possible to smelt metal from their roasting product. Medieval miners and metallurgists considered this to be the tricks of mythical creatures - kobolds (from German Kobold - brownie, dwarf). In 1735, the Swedish chemist G. Brandt, heating a mixture of cafer with coal and flux in a furnace with blowing, obtained a metal, which he called "kobold king". This name was soon changed to "cobolt" and then to "cobalt".

Distribution of cobalt in nature. The content of Cobalt in the lithosphere is 1.8·10 -3% by weight. In the earth's crust, it migrates in magmas, hot and cold waters. During magmatic differentiation, Cobalt accumulates mainly in the upper mantle: its average content in ultramafic rocks is 2·10 -2%. The formation of so-called segregation deposits of cobalt ores is associated with magmatic processes. Concentrating from hot groundwater, Cobalt forms hydrothermal deposits; in them, Co is bound to Ni, As, S, Cu. About 30 Cobalt minerals are known.

In the biosphere, Cobalt is predominantly dispersed, however, in areas where there are plants - Cobalt concentrators, cobalt deposits are formed. At the top earth's crust there is a sharp differentiation of Cobalt - in clays and shales, on average, contains 2·10 -3% Cobalt, in sandstones 3·10 -5, in limestones 1·10 -5. The sandy soils of forest areas are the poorest in Cobalt. IN surface waters There is little cobalt, it is only 5·10 -8% in the World Ocean. Being a weak water migrant, Cobalt easily passes into sediments, being adsorbed by manganese hydroxides, clays, and other highly dispersed minerals.

Physical properties of cobalt. At ordinary temperature and up to 417 °C, the Cobalt crystal lattice is hexagonal close-packed (with periods a = 2.5017Å, c = 4.614Å), above this temperature the Cobalt lattice is face-centered cubic (a = 3.5370Å). Atomic radius 1.25Å, ionic radii Co 2+ 0.78Å and Co 3+ 0.64Å. Density 8.9 g / cm 3 (at 20 ° C); t pl 1493°C, t bp 3100°C. Heat capacity 0.44 kJ/(kg K), or 0.1056 cal/(g °C); thermal conductivity 69.08 W / (m K), or 165 cal / (cm sec ° C) at 0-100 ° C. Electrical resistivity 5.68 10 -8 ohm m, or 5.68 10 -6 ohm cm (at 0 °C). Cobalt is ferromagnetic, and retains ferromagnetism from low temperatures to the Curie point, Θ = 1121 °C. The mechanical properties of Cobalt depend on the method of mechanical and thermal processing. Tensile strength 500 MN / m 2 (or 50 kgf / mm 2) for forged and annealed Cobalt; 242-260 MN/m 2 for cast; 700 MN/m 2 for wire. Brinell hardness 2.8 Gn / m 2 (or 280 kgf / mm 2) for work-hardened metal, 3.0 Gn / m 2 for electrolysis deposited; 1.2-1.3 Gn / m 2 for annealed.

Chemical properties of cobalt. The configuration of the outer electron shells of the Cobalt atom is 3d 7 4s 2 . In compounds, Cobalt exhibits a variable valence. In simple compounds, Co(II) is the most stable; in complex compounds, Co(III). For Co(I) and Co(IV), only a few complex compounds have been obtained. At ordinary temperatures compact Cobalt is resistant to water and air. Finely crushed Cobalt, obtained by reduction of its oxide with hydrogen at 250 °C (pyrophoric Cobalt), ignites spontaneously in air, turning into CoO. Compact Cobalt begins to oxidize in air above 300°C; at red heat, it decomposes water vapor: Co + H 2 O \u003d CoO + H 2. Cobalt easily combines with halogens when heated, forming COX 2 halides. When heated, Cobalt interacts with S, Se, P, As, Sb, C, Si, B, and the composition of the resulting compounds sometimes does not satisfy the above valence states (for example, Co 2 P, Co 2 As, CoSb 2, Co 3 C, CoSi 3). In dilute hydrochloric and sulfuric acids, Cobalt slowly dissolves with the release of hydrogen and the formation of CoCl 2 chloride and CoSO 4 sulfate, respectively. Dilute nitric acid dissolves Cobalt with the release of nitrogen oxides and the formation of nitrate Co(NO 3) 2 . Concentrated HNO 3 passivates Cobalt. The named salts of Co (P) are highly soluble in water [at 25 ° C, 100 g of water dissolve 52.4 g of CoCl 2, 39.3 g of CoSO 4, 136.4 g of Co(NO 3) 2]. Caustic alkalis precipitate blue hydroxide Co (OH) 2 from solutions of Co 2+ salts, which gradually turns brown due to oxidation by atmospheric oxygen to Co (OH) 3. Heating in oxygen at 400-500 ° C converts CoO into black oxide-oxide Co 3 O 4, or CoO · Co 2 O 3 - a spinel-type compound. A compound of the same type CoAl 2 O 4 or CoO Al 2 O 3 of blue color (thenar blue, discovered in 1804 by L. J. Tenar) is obtained by calcining a mixture of CoO and Al 2 O 3 at a temperature of about 1000 ° C.

Of the simple compounds of Co (IP), only a few are known. Under the action of fluorine on powder Co or CoCl 2 at 300-400 ° C, brown fluoride CoF 3 is formed. The Co(III) complex compounds are very stable and easily obtained. For example, KNO 2 precipitates yellow sparingly soluble potassium hexanitrocobaltate (III) K 3 from solutions of Co (P) salts containing CH 3 COOH. Cobaltammines (the former name of cobaltiacs) are very numerous - complex compounds of Co (III) containing ammonia or some organic amines.

Getting cobalt. Cobalt minerals are rare and do not form significant ore accumulations. The main source of industrial production of Cobalt are nickel ores containing Cobalt as an impurity. The processing of these ores is very complex, and its method depends on the composition of the ore. Finally, a solution of chlorides of Cobalt and Nickel is obtained, containing impurities of Cu 2+ , Pb 2+ , Bi 3+ . The action of H 2 S precipitates sulfides of Cu, Pb, Bi, after which Fe (II) is transferred to Fe (III) by passing chlorine and Fe (OH) 3 and CaHAsO 4 are precipitated by adding CaCO 3 . Cobalt is separated from nickel by the reaction: 2CoCl 2 + NaClO + 4NaOH + H 2 O = 2Co(OH) 3 ↓ + 5NaCl. Almost all of the nickel remains in solution. The black precipitate of Co(OH) 3 is calcined to remove water; the obtained oxide Co 3 O 4 is reduced with hydrogen or carbon. Metal Cobalt containing up to 2-3% impurities (Ni, Fe, Cu and others) can be purified by electrolysis.

The use of cobalt. Cobalt is used mainly in the form of alloys; such are cobalt alloys, as well as alloys based on other metals, where cobalt serves as an alloying element. Cobalt alloys are used as heat-resistant and heat-resistant materials, in the manufacture of permanent magnets, cutting tools, and others. Powdered Cobalt, as well as Co 3 O 4 serve as catalysts. Fluoride CoF 3 is used as a strong fluorinating agent, thenar blue and especially cobalt and potassium silicate - as paints in the ceramic and glass industries. Cobalt salts are used in agriculture as microfertilizers, as well as for feeding animals.

From artificially radioactive isotopes Cobalt highest value has 60 Co with a half-life of T ½ = 5.27 years, widely used as a gamma emitter. In technology, it is used for gamma flaw detection. In medicine - mainly for radiation therapy of tumors and for the sterilization of medicines. It also serves to kill insects in grains and vegetables and to preserve food. Other radioactive isotopes - 56 Co (T ½ \u003d 77 days), 57 Co (270 days) and 58 Co (72 days) as less dangerous (short half-life) are used as isotope indicators in the study of metabolism, in particular to study the distribution Cobalt in the body of animals (with the help of radioactive Cobalt, the permeability of the placenta was studied, etc.).

Cobalt in the body. Constantly present in the tissues of animals and plants, Cobalt is involved in metabolic processes. In the animal organism, the content of Cobalt depends on its level in fodder plants and soils. The concentration of Cobalt in plants of pastures and meadows averages 2.2·10 -3 - 4.5·10 -3% per dry matter. The ability to accumulate Cobalt in legumes is higher than that of cereals and vegetable plants. In connection with the high ability to concentrate Cobalt, seaweeds differ little from terrestrial plants in its content, although there is much less Cobalt in sea water than in soils. The daily human need for Cobalt is approximately 7-15 mcg and is met by its intake with food. The need of animals for Cobalt depends on their species, age and productivity. Ruminants need Cobalt the most, for which it is necessary for the development of symbiotic microflora in the stomach (mainly in the rumen). The daily requirement for Cobalt in dairy cows is 7-20 mg, in sheep - about 1 mg. With a lack of Cobalt in the diet, the productivity of animals decreases, metabolism and hematopoiesis are disturbed, and endemic diseases - acobaltoses occur in ruminants. The biological activity of Cobalt is determined by its participation in the construction of the vitamin B 12 molecule and its coenzyme forms, the transcarboxylase enzyme. Cobalt is necessary for the manifestation of the activity of a number of enzymes. It affects the metabolism of protein and the synthesis of nucleic acids, the metabolism of carbohydrates and fats, redox reactions in the animal body. Cobalt is a powerful activator of hematopoiesis and the synthesis of erythropoietins. Cobalt is involved in the enzyme systems of nodule bacteria that fix atmospheric nitrogen; stimulates the growth, development and productivity of legumes and plants of a number of other families.

Cobalt (Co) is a chemical element with atomic number 27. Atomic mass cobalt equals 58.9332. Cobalt, common in nature, consists of 2 stable nuclides: 57Co (0.17% by mass) and 59Co (99.83% by mass). IN periodic system chemical elements of Dmitry Ivanovich Mendeleev, cobalt is in group VIIIB, and also, together with nickel and iron, forms in the fourth period in this group a triad of transition metals with similar properties. The cobalt atom has the configuration of two outer electron layers 3s2p6d74s2. Cobalt forms compounds for the most part in the +2 oxidation state (second valency), and less often forms compounds in the +3 oxidation state (third valence), and very rarely forms compounds in the +5, +4, and +1 oxidation states (respectively , fifth, fourth and first valencies).

Among the three main ferromagnetic metals, i.e. iron, cobalt and nickel - cobalt has the highest Curie point, that is, the temperature at which a metallic substance loses its magnetic properties. For nickel, the Curie point is only 358°C, for iron it is 770°C, and only for cobalt does this point reach 1130°C. Because magnets are used in a wide variety of conditions, incl. at very high temperatures, cobalt was destined to become an essential component of the composition of magnetic steels.

Cobalt metal is industrially produced by the reduction of cobalt oxide with coal, in rare cases with carbon monoxide or hydrocarbons.

Most of the industrially obtained cobalt is spent on the preparation of various alloys. Like tungsten, cobalt is indispensable in metalworking. Metal is the most important part of high-speed tool steels. Titanium or tungsten carbide, i.e. the main component of the superhard alloy, sintered together with cobalt powder. Cobalt attaches grains of carbides, while it gives the alloy greater viscosity and reduces the sensitivity of the alloy to shocks and shocks.

Biological properties

Cobalt is mineral substance, which is an integral part of vitamin B12. As a rule, the content of cobalt is measured in μg (micrograms). Cobalt is indispensable for blood, namely for red blood cells. The intake of metal in the body should come exclusively from food sources. The body of a healthy average person (with a body weight of 70 kilograms) contains approximately 14 mg of cobalt. The daily human need for cobalt is 40-70 mcg. The metal usually accumulates in the blood, bone tissue, spleen, liver, ovaries, pituitary gland. Cobalt is found in bread and baked goods, milk, legumes, liver, and vegetables.

For a living organism, it has been clarified the main role salts of cobalt. They take part in the formation of vitamin B12. Recently, this vitamin has become a common remedy in medical practice; it is injected into the muscles of a patient who, for some reason, does not have enough cobalt in the body.

This requirement is much higher in ruminants, for example, in ordinary dairy cows it is about 20 mg. The trace element cobalt is also involved in the enzymatic processes of fixing atmospheric nitrogen by nodule bacteria. Cobalt compounds in without fail included in microfertilizers. The absence of cobalt contributes to the development of acobaltosis.

Excess cobalt is harmful to humans. The MPC of cobalt dust in the air is 0.5 mg/m³, the permissible content of cobalt salts in drinking water is 0.01 mg/l. Extremely toxic vapors of cobalt octacarbonyl - Co2 (CO) 8. An excess of cobalt can sometimes create a disturbance in the metabolism of iodine within the thyroid gland. Excess cobalt is eliminated with the help of chelating drugs that contain cysteine-N, acetyl-L, symptomatic agents.

Cobalt is used in medicine, in the treatment of malignant tumors with radioactive radiation. On this moment for irradiation of tissues affected by cancer, the radioactive isotope of cobalt 60Co is used, which gives the most homogeneous radiation (in cases where such treatment is possible).

Evaluation of the level of cobalt in the human body is based on the results of urine and blood tests. On average, the content of cobalt in the blood plasma of a healthy person is 0.05-0.1 μg / l, and in the urine - about 0.1-1.0 μg / l.

Causes of cobalt deficiency:

  • - Worm infestation.
  • - Decreased function of the pancreas.
  • - Decreased acidity of gastric juice.
  • - Violation of the exchange of cobalt.
  • - Vitamin B12 deficiency.
  • - Insufficient intake of cobalt.
  • The increased content of iron and protein in food slows down the absorption of cobalt, while copper and zinc, on the contrary, enhance this process.

In the treatment of patients with B12 deficiency anemia, cyanocobalamin and coamide are used. IN Lately Cobalt deficiency correction tools have been developed based on its asparaginate. In case of mild anemia, a diet enriched with vitamin B 12 (heart, liver, kidneys, black pudding, leafy greens) can sometimes be effective.

Scientists have found an Egyptian glass jar, painted with cobalt salts, which dates back to the 15th century BC, as well as glassy blue bricks that also contain cobalt.

Inside the tomb of the Egyptian pharaoh Tutankhamun, they found a huge number of objects made of blue glass. Oddly enough, only one of the objects was painted with cobalt, and all the rest were painted with copper.

All deposits rich in cobalt are almost completely exhausted today.

Cobalt was mentioned by Paracelsus, Biringuccio, Vasily Valentine and other authors of the mid-15th - late 17th centuries. Ruland's "Lexicon of the Alchemists" (dated 1612) says about cobalt something like this: "Cobol cobalt (from Koboltum, Kobaltum) or collet (from Colletum) is a metallic matter that is blacker than iron and lead, stretching when heated. Cobalt - this is a black matter, somewhat similar in color to ash. It can be cast and forged, at the same time it does not have a metallic luster, it is a harmful impurity, which, when smelted, removes good ore along with smoke. " As you might guess, we are talking about metallic cobalt.

In the 60s. cobalt salts have been used by some brewing companies to stabilize foam. Those who drank more than 4 liters of beer a day regularly got strong side effects heart, and, in some cases, this has led to death. There have been cases of so-called cobalt cardiomyopathy associated with beer consumption. Such cases from 64 to 66 years. took place in Minneapolis (Minnesota), Omaha (Nebraska), Quebec (Canada) and Leuven (Belgium). Since that time, the use of cobalt in brewing has been phased out, and it is now illegal to add cobalt to beer.

Cobalt is essential for the human body to absorb vitamin B12. The metal is involved in the regeneration of muscles and hematopoiesis.

Story

Several centuries ago, German Saxony was a large center for the extraction of copper, silver and other non-ferrous metals at that time. In the local mines, ore was found that, according to its external features, was silver, but during the smelting it was not possible to obtain the precious metal. During the roasting of the ore, poisonous gas was released, which poisoned the workers. The Saxons explained these troubles by the intervention dark force, the treacherous dwarf kobold. He was also the cause of other dangers lying in wait in the dungeons of the miners. At that time in Germany, even prayers were read in churches for salvation from the spirit of the kobold miners. And over time, when the miners learned to distinguish dangerous ore from silver, it became known as "kobold".

In 1735, the Swedish chemist Georg Brandt isolated an unknown gray metal with a faint pink tint from "impure" ore. The name "kobold", or "cobalt", remained behind the metal.

In Brandt's dissertation, it was said that safra can be made from cobalt, i.e. paint that gives the glass a very beautiful and deep blue color. Even in ancient Egypt, blue glass was made according to carefully concealed recipes.

In the Middle Ages, the Republic of Venice was the European leader in glass production. In order to protect the secrets of making colored glass from prying ears, in the XII century. The government of Venice legally transferred all existing glass factories to the island of Murano. There are real legends about the confidentiality of Murano glass production technologies. Once, an apprentice Giorgio Belerino escaped from the island of Murano, and soon a glass workshop burned down in a German town. The owner's name was Belerino, he was stabbed to death with a dagger.

Still, the secrets of making colored glass spread to other states. In Germany in 1520, Weidenhammer found a method for making blue glass paint and sold it "at a high price" to the Venetian government. 20 years later, Schürer, a Bohemian glassmaker, also began to produce blue paint from an ore known only to him. After such paint began to be made in Holland. They wrote that the glass was stained with "zaffer", but this product consisted of cheo - it was a secret. Only a century later, the famous scientific chemist Johann Kunkel in 1679 described in detail the production of paint, but it still remained a mystery what kind of ore it was made from, where to look for this ore, and what part of the ore has a coloring property.

Only Brandt's research found that zaffer or saffron is a product obtained by calcining cobalt-rich ore, which contains cobalt oxides, as well as oxides of other metals. Then zaffer fused with potash and sand formed smalt, which is glass paint. Smalt contained a little cobalt - no more than 2-7%. But the coloring property of cobalt oxide turned out to be great: even 0.0001% of it in the mixture gives a bluish tint to the glass.

One French chemist in 1737 discovered the property of cobalt salts to be colored as a result of heating. He used the salts as a sympathetic ink. Now this feature is of practical importance in technology. Using a solution of cobalt salts, porcelain crucibles are labeled. As a result of heating, the mark begins to clearly appear on the surface of the porcelain.

Glasses colored with cobalt oxide have no rivals in terms of transparency. For photochemical studies, glasses are sometimes needed that do not transmit yellow and orange rays. This condition is 100% met by cobalt-ruby glasses. To do this, a heated glass, colored red with copper compounds, is applied to blue glass dyed with cobalt. Known use of cobalt oxide to give a beautiful color to enamel and porcelain products.

Being in nature

The content of cobalt in the composition of the earth's crust is an insignificant fraction, approximately 0.003% by weight. But a huge part of cobalt is located in the very center of the Earth's core, where the chemical elements of the iron group mainly predominate. Cobalt in the lithosphere is on average about 0.003% by weight, cobalt compounds are found in iron meteorites (about 0.6%) and stone meteorites (about 0.08%). Negligibly small amounts of cobalt are contained in the water of the world's oceans ((1-7) 10-10% cobalt.), As well as in mineral springs.

Cobalt is found in more than thirty minerals, which include linneite Co3S4, carrolite CuCo2SO4, cobaltite CoAsS, smaltite CoAs2, spherocobaltite CoCO3, skutterudite CoAs3, schmaltinhloanthin (Co, Ni, Fe) As3, safflorite (Co, Fe) As2 and many others . As a rule, in nature, cobalt is accompanied by its neighbors, elements of the fourth period - copper, nickel, manganese and iron. Sea water contains about (1-7) 10-10% cobalt.

Using spectral analysis, scientists have established the presence of cobalt in the atmosphere of the Sun, as well as in the atmospheres of various stars. In nature, there are two stable isotopes of cobalt: 57Co and 59Co. The exact content of cobalt in the earth's crust is 4 * 10-3%. occasionally cobalt

In negligible amounts, cobalt is found in the tissues of plants and animals, in particular, cobalt is part of such a vitamin as B12 (C63H88O14N14PCo).

Cobalt metal is obtained by reduction of oxides, complex compounds (Cl2, CO3), salts, carbon monoxide, hydrogen, carbon or methane (during heating), silicon or aluminothermic reduction of cobalt oxides, thermal decomposition by electrolysis of aqueous solutions of CoSO4 * 7H2O salts, Co4(CO)12, and carbonyls Co2(CO)8, or (NH4)2SO4*CoSO4*6H2O.

In the earth's crust, cobalt migrates in magmas, cold and hot waters. During magmatic differentiation, cobalt accumulates in its bulk in the upper mantle; the average content of cobalt in ultramafic rocks is 2·10-2%. The formation of segregation deposits of cobalt ores, as they are commonly called, is also associated with magmatic processes. Cobalt, in the process of concentration from hot groundwater, is able to form hydrothermal deposits. In such deposits, cobalt is associated with Cu, Ni, S and As.

Cobalt is predominantly dispersed in the biosphere, however, in areas where plants are present - Cobalt concentrators, cobalt deposits can form. In the uppermost part of the earth's crust of our planet, Cobalt differentiation is observed: in shales and clays, cobalt contains an average of 2 10-3%, in limestones 1 10-5, in sandstones 3 10-5. Sandy soils in forested areas are the poorest in cobalt. There is little cobalt in surface waters, its content in the world ocean is only 5·10-8%. Because cobalt is a weak water migrant, the metal tends to easily pass into sediments, while being adsorbed by manganese hydroxides, as well as clays and other highly dispersed minerals.

Application

Most of the industrially obtained cobalt is spent on the preparation of various alloys. Like tungsten, cobalt is indispensable in metalworking. Metal is the most important part of high-speed tool steels. Titanium or tungsten carbide, i.e. the main component of the superhard alloy, sintered together with cobalt powder. Cobalt attaches grains of carbides, while it gives the alloy greater viscosity and reduces the sensitivity of the alloy to shocks and shocks.

Such hard alloys serve not only for the manufacture of special cutting tools. In some cases, carbide has to be welded onto parts that are subject to heavy wear during machine operation. Such a cobalt-based alloy can increase the life of a steel part by 4 to 8 times. Additives of cobalt make it possible to increase the heat resistance of the alloy, improve the mechanical and other properties of steel.

Only a few metals, including cobalt, have such an ability as the preservation of magnetic properties after repeated magnetization. Alloys and steels from which magnets are made are subject to particularly important technical requirements: they must have a large coercive force, or, in other words, resistance to demagnetization. Manufactured magnets must be stable and in relation to temperature effects, resistant to vibration (this is especially important in various motors), must be machined.

When exposed to heat, a magnetized metal usually loses its ferromagnetic properties. This happens when different temperature(Curie point): for iron, the threshold is T = 769°C, for nickel, T = 358°C, and for cobalt, the temperature reaches 1121°C. Back in 1917, a steel alloy with high magnetic properties was patented in Japan. The main component of the updated steel, which was called "Japanese", is cobalt in huge number, up to 60%. Chromium tungsten or molybdenum give high hardness to magnetic steel, while cobalt increases the coercive force of the alloy by 3.5 times. Magnets made from this steel are 3 to 4 times smaller and shorter. There is another very important property: tungsten steel loses its magnetic properties by about 1/3 under the action of vibrations, and cobalt steels by only 2-3.5%.

In automation, cobalt magnetic devices are used at every turn. The best magnetic materials are cobalt alloys and steels. The property of non-demagnetization of cobalt under the action of high temperatures and vibrations plays an important role in both space and rocket technology.

Cobalt alloys are used in the production of electric motor cores, they are used in transformers, as well as in other electrical devices. In the manufacture of magnetic recording heads, magnetically soft cobalt alloys are used. Hard magnetic cobalt alloys like PrCo5, SmCo5, and others with high magnetic energy are used in instrumentation. In the manufacture of permanent magnets, alloys are used with a content of 52% cobalt, as well as 5-14% vanadium or chromium (vicalloy).

Cobalt, like some metal compounds, serves as a catalyst. Cobalt compounds, when introduced into glass during melting, give a beautiful cobalt (blue) color to glass products. Cobalt compounds are used as pigments in many dyes. In the production of lithium batteries, lithium cobaltate is used, which serves as a highly effective positive electrode. Cobalt silicide is an excellent thermoelectric material; it allows the production of thermoelectric generators with very high efficiency.

Cobalt is also used in medicine, in the treatment of malignant tumors with radioactive radiation. Currently, the radioactive isotope of cobalt 60Co is used to irradiate tissues affected by cancer, which gives the most homogeneous radiation (in cases where such treatment is possible).

Production

Cobalt is a relatively rare metal, and all rich deposits of cobalt today are almost completely exhausted. That is why raw materials containing cobalt (mainly nickel ores that contain cobalt as an impurity, but cobalt minerals are extremely rare, they usually do not form significant for industrial production ore accumulations) are initially enriched, then a concentrate is obtained from this raw material. After that, in order to extract cobalt, the resulting concentrate is either treated with a solution of sulfuric acid or an ammonia solution, or the concentrate is processed into a metal or sulfide alloy by pyrometallurgy. This alloy after production is leached with sulfuric acid.

In some cases, to extract cobalt, sulfuric acid, or as it is called "heap", leaching of the original ore can be carried out (in this case, the crushed ore is placed in high heaps, which are installed on special concrete platforms, and all this is poured over with a leaching solution). In the process of purification of cobalt from undesirable impurities accompanying it, extraction is increasingly being used.

Most challenging task when separating cobalt from accompanying impurities, it is the separation of cobalt from another metal, which is as close as possible to the metal in its chemical properties - nickel. In the process of purification of cobalt from undesirable impurities accompanying it, extraction is increasingly being used. A solution that contains these two metal cations is often treated with powerful oxidizing agents, such as chlorine dibo sodium hypochlorite NaOCl. Reaction:

2CoCl2 + NaOCl + 4NaOH + H2O 2Co(OH)3v + 5NaCl

The final stage of cobalt purification (the so-called refining) is carried out by electrolysis of a sulfate aqueous solution of cobalt, to which boric acid H3BO3.

Co(OH)3, which is a black precipitate, is calcined to remove water, and the oxide Co3O4 obtained during the purification process is reduced with carbon or hydrogen. Cobalt metal, which contains up to 2% to 3% impurities (usually nickel, copper, iron among them), can be easily purified by electrolysis.

Cobalt metal is industrially produced by the reduction of cobalt oxide with coal, in rare cases with carbon monoxide or hydrocarbons. For all this, it is necessary to prepare a mass of 2 parts of molasses, 4 parts of charcoal, 95 parts of CoO, and also enough a large number water. This mass is mixed with a kneading machine, pressed in metal molds, and then, after preliminary drying, cut into cubes and dried again. After that, the cubes are sprinkled with coal powder and heated to a temperature of 1220 ° C in a reducing flame, while the metals are carburized and reduced. In the end, the metal is alloyed in crucibles with the presence of cobalt oxide and borax at a temperature of 1800 to 2000 ° in order to decarburize the metal. In white-hot heat, the resulting cobalt is welded with steel, while iron, which is coated on both sides with cobalt, is rolled out into extremely thin sheets.

The use of metallic cobalt is rather limited. It is used for the preparation of ferrocobalt, as well as for the production of steel with an admixture of cobalt, and for the production of various alloys with copper. Cobalt is also used to cobalt metals. The main area of ​​use of cobalt is the manufacture of paints.

Physical Properties

Cobalt is a hard metal that exists in only two modifications. At temperatures from room temperature up to 427 °C, the α-modification is more stable. And at a temperature from 427 ° C up to reaching the melting point (namely 1494 ° C), the β-modification is stable (cubic lattice, face-centered). Cobalt is a ferromagnet with a Curie point of 1121°C. The metal has a yellowish tint, which gives it the thinnest layer of oxides.

Cobalt. Common in nature, it consists of 2 stable nuclides: 57Co (0.17% by mass) and 59Co (99.83% by mass). In the periodic system of chemical elements of Dmitry Ivanovich Mendeleev, cobalt is in group VIIIB, and together with nickel and iron forms in the fourth period in this group a triad of transition metals with similar properties. The cobalt atom has the configuration of two outer electron layers 3s2p6d74s2. Cobalt forms compounds for the most part in the +2 oxidation state (second valency), and less often forms compounds in the +3 oxidation state (third valence), and very rarely forms compounds in the +5, +4, and +1 oxidation states (respectively , fifth, fourth and first valencies).

A neutral cobalt atom has a radius of 0.125 nm, and the radius of ions (which have a coordination number of 6) is Co4+ - 0.064 nm, Co3+ - 0.069 nm and Co2+ - 0.082 nm. The successive ionization energies of an atom of the element cobalt are 7.865, 17.06, 33.50, 53.2 and 82.2 eV. The electronegativity of cobalt on the Pauling scale is 1.88. Cobalt is a heavy, silvery white, lustrous metal with a pinkish tint.

Cobalt chloride is the cobalt salt of hydrochloric (hydrochloric) acid.

Cobalt chloride belongs to the class of cobalt halides. Salt has the appearance of paramagnetic hygroscopic brilliant blue hexagonal crystals, the color of which becomes blue when dehydrated.

Cobalt chloride has a boiling point of 1049°C and a melting point of 735°C (some other sources state 724°C). The molar electrical conductivity of cobalt chloride at infinite dilution and at a temperature of 25 °C is 260.7 cm cm²/mol. The relative density of the substance (for comparison, water = 1) is 3.356.

At a temperature of 770°C, the vapor pressure of cobalt chloride is 5.33 kPa. Chloride is highly soluble in water, ethyl and methyl alcohols, as well as in acetone. Cobalt chloride does not dissolve in methyl acetate and pyridine. Solubility in water: at room temperature 20 °C solubility 52.9 g / 100 ml, and at a reduced temperature of 7 °C solubility is already 45.0 g / 100 ml

Chemical properties

Compact cobalt is stable in air; when heated above 300°C, the metal is covered with an oxide film, which is a highly dispersed pyrophoric cobalt. Cobalt does not interact with water, water vapor in the air, solutions of carboxylic and alkali acids. The surface of cobalt is passivated by concentrated nitric acid, as is the surface of iron.

Cobalt is located between nickel and iron in the electrochemical series of voltages of various metals. It interacts with almost all other elements. When heated, cobalt combines with halogens to form halides. When exposed to fluorine on powdered cobalt or CoCl2, cobalt is reduced to trivalent cobalt and forms CoF3 fluoride. When heated, cobalt acts with phosphorus, sulfur, selenium, carbon, arsenic, antimony, boron and silicon, and valences from +1 to +6 appear. As a result of the reaction of freshly reduced cobalt powder with H2S, sulfides are formed. At T = 400 °C, Co3S4 is formed; at T = 700 °C, CoS is formed. Sulfide is also formed in the interaction of cobalt and sulfur dioxide at T = 800 °C.

In dilute hydrochloric or sulfuric acid, cobalt dissolves slowly, releasing hydrogen and forming CoCl2 chloride or CoSO4 sulfate. Diluted nitric acid is capable of dissolving cobalt and releasing nitrogen oxides and forming Co(NO3)2 nitrate. Concentrated nitric acid simply passivates the cobalt. Cobalt salts are soluble in water. Alkalis are precipitated from an aqueous solution of salts hydroxide Co (OH) 2 .

There are several oxides of cobalt. CoO - cobalt (II) oxide has the most important properties. It exists in 2 polymorphic modifications: the a- form (cubic lattice), is stable at temperatures from room temperature up to 985 ° C, and the b- form (cubic lattice) exists at high temperatures. Cobalt oxide can be obtained either by heating cobalt hydroxorcarbonate Co(OH)2CoCO3 in an inert atmosphere, or by careful reduction of Co3O4.

If cobalt hydroxide Co(OH)2, its nitrate Co(NO3)2, or hydroxocarbonate are calcined in air at Т = ~700°C, Co3O4(CoO·Co2O3) cobalt oxide is formed. This oxide is similar in its chemical behavior to Fe3O4. These oxides are relatively easily reduced to free metals with the help of hydrogen:

Co3O4 + 4H2 = 3Co + 4H2O.

When calcining Co (OH) 2, Co (NO3) 2, etc. at T = 300 ° C, one more cobalt oxide is obtained - this is Co2O3. When an alkali solution is added to a cobalt(II) salt solution, an easily oxidized Co(OH)2 precipitate is formed. When heated in air at temperatures slightly above 100°C, Co(OH)2 transforms into CoOOH.

If you act with alkali on aqueous solutions of salts of 2-valent cobalt with strong oxidizing agents, Co (OH) 3 is formed.

When heated, cobalt reacts with fluorine to form CoF3 trifluoride. If CoO or CoCO3 is exposed to gaseous HF, one more cobalt fluoride is formed, i.e. CoF2. When cobalt is heated, it reacts with bromine and chlorine, forming CoBr2 dibromide and CoCl2 dichloride. In the reaction of metallic cobalt and gaseous HI at a temperature of 400-500°C, cobalt diiodide CoI2 can be produced.

Fusion of sulfur and cobalt powder gives cobalt sulfide CoS of silver-gray color (b-modification). And if an electric current of hydrogen sulfide H2S is passed through a solution of cobalt (II) salt, CoS - black cobalt sulfide (a-modification) will precipitate:

CoSO4 + H2S = CoS + H2SO4

There are cobalt salts that are soluble in water - CoCl2 chloride, Co(NO3)2 nitrate, CoSO4 sulfate, etc. Dilute aqueous solutions of these salts have a pale pink color. When these salts are dissolved in acetone or alcohol, a dark blue solution is produced. If you add water to this solution, its color turns into a pale pink.