DEFINITION
In the form of a simple substance vanadium gray refractory metal with a body-centered cubic lattice. Located in the fourth period of group V of the secondary (B) subgroup of the Periodic table.
Density - 6.11 g/cm3. The melting and boiling points are 1920 o C and 3400 o C, respectively. The physicochemical properties of vanadium strongly depend on the purity of the metal. Thus, pure metal is malleable, while the presence of impurities in it greatly impairs its ductility and increases its hardness. Under normal conditions it is a chemically resistant metal.
Valence of vanadium in compounds
Vanadium is in the fourth period in the VB group of the Periodic Table D.I. Mendeleev. The atomic number is 23. The nucleus of a vanadium atom contains 23 protons and 27 neutrons (mass number is 50). The vanadium atom has four energy levels containing 23 electrons (Fig. 1).
Rice. 1. Structure of the vanadium atom.
The electronic formula of the vanadium atom in the ground state is as follows:
1s 2 2s 2 2p 6 3s 2 3p 6 3d 3 4s 2 .
And the energy diagram (constructed only for electrons of the outer energy level, which are otherwise called valence):
The presence of three unpaired electrons indicates that vanadium in its compounds can exhibit valency III (V III 2 O 3, V III F 3, V III Cl 3).
The vanadium atom is capable of transitioning to an excited state: the electrons of the 4s sublevel are vaporized and one of them occupies a vacant orbital of the 3d sublevel:
The presence of five unpaired electrons indicates that vanadium also exhibits the valency V in its compounds (V V 2 O 5, V V F 5).
It is known that vanadium has valencies II (V II O) and IV (V IV O 2, V IV Cl 4).
Examples of problem solving
EXAMPLE 1
Vanadium(vanadium), v, chemical element of group V of the periodic system of Mendeleev; atomic number 23, atomic mass 50.942; metal gray-steel color. Natural V. consists of two isotopes: 51 v (99.75%) and 50 v (0.25%); the latter is weakly radioactive (half-life T 1/2 = 10 14 years). V. was discovered in 1801 by the Mexican mineralogist A. M. del Rio in Mexican brown lead ore and was named after the beautiful red color of the heated salts erythronium (from the Greek erythr o s - red). In 1830, the Swedish chemist N. G. Sefström discovered a new element in iron ore from Taberg (Sweden) and named it V. in honor of the Old Norse goddess of beauty Vanadis. In 1869, the English chemist G. Roscoe obtained powdered metal V. by reducing vcl 2 with hydrogen. V. has been mined on an industrial scale since the beginning of the 20th century.
The V content in the earth's crust is 1.5-10 -2% by weight; it is a fairly common element, but dispersed in rocks and minerals. Of the large number of V. minerals, patronite, roscoelite, decloysite, carnotite, vanadinite, and some others are of industrial importance. Important sources of V. are titanomagnetite and sedimentary (phosphorous) iron ores, as well as oxidized copper-lead-zinc ores. V. is extracted as a by-product during the processing of uranium raw materials, phosphorites, bauxites, and various organic deposits (asphaltites, oil shale).
Physical and chemical properties. V. has a body-centered cubic lattice with a period a = 3.0282 å. In its pure state, V. is forged and can be easily processed by pressure. Density 6.11 G/ cm 3 , t pl 1900 ± 25°С, t bale 3400°C; specific heat capacity (at 20-100°C) 0.120 feces/ ggrad; thermal coefficient of linear expansion (at 20-1000°C) 10.6·10 -6 hail-1, electrical resistivity at 20 °C 24.8·10 -8 ohm· m(24.8·10 -6 ohm· cm), below 4.5 K V. it goes into a state of superconductivity. Mechanical properties of high purity V. after annealing: elastic modulus 135.25 n/ m 2 (13520 kgf/ mm 2), tensile strength 120 nm/ m 2 (12 kgf/ mm 2), elongation 17%, Brinell hardness 700 pl/ m 2 (70 kgf/ mm 2). Gas impurities sharply reduce the plasticity of fiber and increase its hardness and fragility.
At ordinary temperatures, V. is not exposed to air, sea water, and alkali solutions; resistant to non-oxidizing acids, with the exception of hydrofluoric acid. In terms of corrosion resistance in hydrochloric and sulfuric acids, V. is significantly superior to titanium and stainless steel. When heated in air above 300°C, it absorbs oxygen and becomes brittle. At 600-700°C, V. is intensively oxidized with the formation of pentoxide v 2 o 5, as well as lower oxides. When V is heated above 700°C in a nitrogen stream, nitride vn ( t mp 2050°C), stable in water and acids. V. interacts with carbon at high temperatures, giving refractory carbide vc ( t pl 2800°C), which has high hardness.
V. gives compounds corresponding to valences 2, 3, 4 and 5; Accordingly, the following oxides are known: vo and v 2 o 3 (having a basic character), vo 2 (amphoteric) and v 2 o 5 (acidic). Compounds of 2- and 3-valent vitreous are unstable and are strong reducing agents. Compounds of higher valences are of practical importance. V.'s tendency to form compounds of different valencies is used in analytical chemistry and also determines the catalytic properties of v 2 o 5. V. pentoxide dissolves in alkalis to form vanadates.
Receipt and application. To extract minerals, the following is used: direct leaching of ore or ore concentrate with solutions of acids and alkalis; firing of the raw material (often with nacl additives) followed by leaching of the fired product with water or dilute acids. Hydrated V pentoxide is isolated from solutions by hydrolysis (at pH = 1-3). When vanadium-containing iron ores are smelted in a blast furnace, V is converted into cast iron, during the processing of which slag containing 10-16% v 2 o 5 is obtained into steel. Vanadium slags are roasted with table salt. The burned material is leached with water and then with dilute sulfuric acid. V 2 o 5 is isolated from solutions. The latter is used for smelting ferrovanadium(iron alloys with 35-70% V.) and obtaining metal V. and its compounds. Malleable metal V. is obtained by calcium-thermal reduction of pure v 2 o 5 or v 2 o 3; reduction of v 2 o 5 with aluminum; vacuum carbon-thermal reduction v 2 o 3; magnesium-thermal reduction vc1 3; thermal dissociation of iodide. V. is melted in vacuum arc furnaces with a consumable electrode and in electron beam furnaces.
Ferrous metallurgy is the main consumer of metal (up to 95% of all metal produced). V. is a component of high-speed steel, its substitutes, low-alloy tool steels, and some structural steels. With the introduction of 0.15-0.25% V., the strength, toughness, fatigue resistance and wear resistance of steel sharply increase. V., introduced into steel, is both a deoxidizing and carbide-forming element. V. carbides, distributed in the form of dispersed inclusions, prevent grain growth when the steel is heated. V. is introduced into steel in the form of a master alloy - ferrovanadium. V. is also used for alloying cast iron. A new consumer of titanium is the rapidly developing industry of titanium alloys; some titanium alloys contain up to 13% V. In aviation, rocket and other fields of technology, alloys based on niobium, chromium and tantalum containing V additives have been used. Heat-resistant and corrosion-resistant alloys based on V with the addition of ti, nb have been developed. , w, zr and al, the use of which is expected in aviation, rocket and nuclear technology. Of interest are superconducting alloys and V compounds with ga, si, and ti.
Pure metallic V. is used in nuclear energy (shells for fuel elements, pipes) and in the production of electronic devices.
V. compounds are used in the chemical industry as catalysts, in agriculture and medicine, in the textile, paint and varnish, rubber, ceramic, glass, photo and film industries.
V. compounds are poisonous. Poisoning is possible by inhaling dust containing compounds B. They cause irritation of the respiratory tract, pulmonary hemorrhages, dizziness, disturbances in the functioning of the heart, kidneys, etc.
V. in the body. V. is a permanent component of plant and animal organisms. The source of water is igneous rocks and shales (containing about 0.013% water), as well as sandstones and limestones (about 0.002% water). In soils, V. is about 0.01% (mainly in humus); in fresh and sea waters 1·10 7 -2·10 7%. In terrestrial and aquatic plants, the content of V. is significantly higher (0.16-0.2%) than in terrestrial and marine animals (1.5·10 -5 -2·10 -4%). V. concentrators are: the bryozoan plumatella, the mollusk pleurobranchus plumula, the sea cucumber stichopus mobii, some ascidians, from molds - black aspergillus, from mushrooms - toadstool (amanita muscaria). The biological role of V. has been studied in ascidians, in whose blood cells V. is in a 3- and 4-valent state, that is, there is a dynamic equilibrium.
The physiological role of V. in ascidians is associated not with the respiratory transfer of oxygen and carbon dioxide, but with redox processes—the transfer of electrons using the so-called vanadium system, which probably has physiological significance in other organisms.
Lit.: Meerson G. A., Zelikman A. N., Metallurgy of rare metals, M., 1955; Polyakov A. Yu., Fundamentals of vanadium metallurgy, M., 1959; Rostoker U., Vanadium Metallurgy, trans. from English, M., 1959; Kieffer p., Brown H., Vanadium, niobium, tantalum, trans. from German, M., 1968; Handbook of Rare Metals, [trans. from English], M., 1965, p. 98-121; Refractory materials in mechanical engineering. Directory, M., 1967, p. 47-55, 130-32; Kovalsky V.V., Rezaeva L.T., The biological role of vanadium in ascidians, “Advances of modern biology”, 1965, v. 60, v. 1(4); Bowen N. j. M., trace elements in biochemistry, l. - n. y., 1966.
I. Romankov. V. V. Kovalsky.
Vanadium is a chemical element symbolized by the symbol "V". The atomic mass of vanadium is 50.9415 a. e.m., atomic number - 23. It is a hard silver-gray, malleable and fusible metal, rarely found in nature. It is found in over 60 minerals and can even be found in fossil fuels.
Unrecognized discovery
The metal vanadium was first discovered by Spanish-born Mexican mineralogist Andres Manuel Del Rio in 1801. A researcher has extracted a new element from a sample of “brown” lead ore mined in Mexico. As it turns out, the metal's salts have a wide variety of colors, so Del Rio originally named it "panchromium" (from the Greek "παγχρώμιο" - "multi-colored").
The mineralogist later renamed the element erythronium (from the Greek "ερυθρός" - "red"), because most salts turned red when heated. It would seem that incredible luck smiled on a little-known scientist in Europe. The discovery of the new chemical element vanadium promised, if not fame, then at least recognition from colleagues. However, due to the lack of significant authority in the scientific world, the Mexican’s achievement was ignored.
In 1805, the French chemist Hippolyte Victor Collet-Decotils suggested that the new element studied by Del Rio was just a sample of lead chromate with impurities. Ultimately, the Mexican researcher, in order not to completely lose face in front of the scientific fraternity, accepted Collet-Decotille's statement and abandoned his discovery. However, his achievement did not fade into oblivion. Today, Andres Manuel Del Rio is recognized as the discoverer of the rare metal.
Reopening
In 1831, the Swede Nils Gabriel Sefström rediscovered the chemical element vanadium in the oxide he obtained while working with iron ore. The scientist chose the letter “V” as its designation, which has not yet been assigned to any element. Säfström named the new metal because of its beautiful and rich coloring after the Old Norse goddess of beauty Vanadis.
The news aroused increased interest in the scientific community. We immediately remembered the work of the Mexican mineralogist. In the same 1831, Friedrich Wöhler rechecked and confirmed Del Rio's previous discovery. And geologist George William Featherstonhoop even proposed calling the metal “rionium” in honor of the discoverer, but the initiative was not supported.
Elusive
Isolating vanadium metal in its pure form has proven difficult. Before this, scientists worked only with its salts. That is why the true properties of vanadium are unknown. In 1831, Berzelius reported obtaining a metallized substance, but Henry Enfield Roscoe proved that Berzelius had actually produced vanadium nitride (VN). Roscoe eventually produced the metal in 1867 by reducing vanadium chloride (VCl 2) with hydrogen. Since 1927, pure vanadium has been obtained by reducing vanadium pentoxide with calcium.
The first serial industrial use of the element dates back to 1905. The metal was added to a steel alloy to make racing car chassis and later to the Ford Model T. Vanadium's characteristics help reduce structural weight while increasing tensile strength. By the way, the German chemist Martin Henze discovered vanadium in the blood cells (or coelomic cells) of marine inhabitants - accidia - in 1911.
Physical properties
Vanadium is a malleable gray-blue metal of medium hardness with a steely luster and a density of 6.11 g/cm³. Some sources describe the material as soft, meaning its high ductility. The crystal structure of the element is more complex than most metals and steels.
Vanadium has good resistance to corrosion, alkalis, sulfuric and hydrochloric acids. It oxidizes in air at about 660°C (933K, 1220°F), although passivation of the oxide occurs even at room temperature. This material melts when the temperature reaches 1920°C, and boils at 3400°C.
Chemical properties
Vanadium, when exposed to oxygen, forms four types of oxides:
Type (II) vanadium compounds are reducing agents, and type (V) compounds are oxidizing agents. Compounds (IV) often exist as derivatives of the vanadyl cation.
Oxide
The most commercially important compound is vanadium pentoxide. It is a brownish-yellow solid, although when freshly precipitated from aqueous solution its color is dark orange.
The oxide is used as a catalyst for the production of sulfuric acid. This compound oxidizes sulfur dioxide (SO 2) into trioxide (SO 3). In this redox reaction, sulfur is oxidized from +4 to +6, and vanadium is reduced from +5 to +4. The formula for vanadium is as follows:
V 2 O 5 + SO 2 → 2VO 2 + SO 3
The catalyst is regenerated by the oxidation of oxygen:
2VO 2 + O 2 → V 2 O 5
Similar oxidation processes are used in the production of maleic anhydride, phthalic anhydride and several other bulk organic compounds.
This oxide is also used in the preparation of ferrovanadium. It is heated with iron and ferrosilicon with the addition of lime. When aluminum is used, an iron-vanadium alloy is produced along with aluminum oxide as a by-product. Due to its high coefficient of thermal resistance, vanadium(V) oxide is used as a detector material in bolometers and microbolometer arrays in thermal imaging instruments.
Characteristics
Rare metal has the following characteristics:
- Crystal structure: body-centered cubic.
- Sound conductivity: 4560 m/s (at 20°C).
- Valence of vanadium: V (less often IV, III, II).
- Thermal expansion: 8.4 µm/(m K) (at 25°C).
- Thermal conductivity: 30.7 W/(m K).
- Electrical resistance: 197 nΩ m (at 20°C).
- Magnetism: paramagnetic.
- Magnetic susceptibility: +255·10 -6 cm 3 /mol (298K).
- Elastic modulus: 128 GPa.
- Shear modulus: 47 GPa.
- Bulk modulus of elasticity: 160 GPa.
- Poisson's ratio: 0.37.
- Hardness on the Mohs scale: 6.7.
- Vickers hardness: 628-640 MPa.
- Brinell hardness: 600-742 MPa.
- Element category: transition metal.
- Electronic configuration: 3d 3 4s 2.
- Heat of fusion: 21.5 kJ/mol.
- Heat of evaporation: 444 kJ/mol.
- Molar heat capacity: 24.89 J/(mol K).
Vanadium in the periodic table is in the 5th group (vanadium subgroup), 4th period, d-block.
Spreading
Vanadium on the scale of the Universe is approximately 0.0001% of the total volume of matter. It is as common as copper and zinc. The metal was discovered in the spectral glow of the Sun and other stars.
The element is the 20th most abundant in the earth's crust. The metal vanadium is quite rare in crystalline form, but compounds of this material are found in 65 different minerals. The economically significant of them are patronite (VS 4), vanadinite (Pb 5 (VO 4) 3 Cl) and carnotite (K 2 (UO 2) 2 (VO 4) 2 3 H 2 O).
Vanadyl ions are abundant in seawater and have an average concentration of 30 nMa. Some mineral water sources also contain these ions in high concentrations. For example, springs near Mount Fuji contain up to 54 µg/l.
Production
Most of this rare metal is obtained from vanadium magnetite, found in ultramafic igneous gabbro rocks. Raw materials are mined mainly in South Africa, northwestern China and eastern Russia. In 2013, these countries produced more than 97% of all vanadium (79,000 tons by weight).
The metal is also present in bauxite and deposits of crude oil, coal, oil shale and tar sands. Concentrations up to 1200 ppm have been reported in crude oil. Due to the oxidizing properties of vanadium (some of its oxides), after combustion of such petroleum products, residues of the element can cause corrosion in engines and boilers.
An estimated 110,000 tons of the substance are released into the atmosphere each year by burning fossil fuels. Today, technologies are being developed to extract valuable substances from hydrocarbons.
Production
Vanadium is primarily used as an additive to steel alloys called ferroalloys. Ferrovanadium is produced directly by reducing a mixture of valence (V) vanadium oxide, iron oxides and pure iron in an electric furnace.
The metal is produced using a multi-step process that begins by roasting ground vanadium magnetite ore with the addition of sodium chloride (NaCl) or sodium carbonate (Na2CO3) at about 850°C to produce sodium metavanadate (NaVO3). An aqueous extract of this substance is acidified to obtain a polyvanadate salt, which is reduced with calcium metal. As an alternative to small-scale production, vanadium pentoxide is reduced with hydrogen or magnesium.
Many other methods are also used, all of which produce vanadium as a by-product of other processes. Its purification is possible using the iodide method, developed by Anton Eduard van Arkel and Jan Hendrik de Boer in 1925. It involves the formation of vanadium (III) iodide and its subsequent decomposition to produce pure metal:
2 V + 3I 2 ⇌ 2 VI 3
The Japanese came up with a rather exotic way to obtain this element. They breed ascidians (a type of chordata) in underwater plantations, which absorb vanadium from sea water. They are then collected and burned. Valuable metal is extracted from the resulting ash. By the way, its concentration in this case is much higher than in the richest deposits.
Alloys
What are vanadium alloys? Approximately 85% of the rare metal produced is used to produce ferrovanadium or as an additive to steel. At the beginning of the 20th century, it was discovered that even a small amount of vanadium significantly increases the strength of steel. This element forms stable nitrides and carbides, which leads to improved characteristics of steels and alloys.
Since that time, vanadium has been used in axles, frames, crankshafts, gears and other important components of wheeled vehicles. There are two groups of alloys:
- High carbon with a content of 0.15% to 0.25% vanadium.
- High-speed tool steels (HSS) containing from 1% to 5% of this element.
Hardnesses above HRC 60 can be achieved for HSS grade steels. They are used in surgical instruments. In powder metallurgy, alloys can contain up to 18% vanadium. The high carbide content in these alloys significantly increases wear resistance. Tools and knives are made from them.
Due to its properties, vanadium stabilizes the beta form of titanium, increases its strength and temperature stability. Mixed with aluminum in titanium alloys, it is used in jet engines, high-speed aircraft and dental implants. The most common alloy for seamless pipes is titanium 3/2.5, containing 2.5% vanadium. These materials are widely used in the aerospace, defense and bicycle industries. Another common alloy, produced primarily in sheets, is titanium 6AL-4V, which is 6% aluminum and 4% vanadium.
Several vanadium alloys exhibit superconducting properties. The first phase superconductor A15 was a vanadium compound V 3 Si, which was obtained in 1952. Vanadium gallium tape is used in superconducting magnets. The structure of the superconducting phase A15 V 3 Ga is similar to the structure of more common superconductors: triniobium stannide (Nb 3 Sn) and niobium titanium (Nb 3 Ti).
Recently, scientists have discovered that in the Middle Ages, small amounts of vanadium (from 40 to 270 parts per million) were added to some samples of Damascus and damask steel. This improved the properties of the blades. However, it is unclear where and how the rare metal was mined. Perhaps it was part of some ores.
Application
In addition to metallurgy, vanadium is used for other applications. The thermal neutron capture cross section and short half-life of the isotopes produced by neutron capture make the metal a suitable material for use inside a fusion reactor.
The most common vanadium oxide, V 2 O 5 pentoxide, is used as a catalyst in the production of sulfuric acid and as an oxidizing agent in the production of maleic anhydride. Vanadium foam is used in the manufacture of ceramic products.
The metal is an important component of mixed metal oxide catalysts used in the oxidation of propane and propylene to acrolein, acrylic acid, or the ammoxidation of propylene to acrylonitrile. Another vanadium oxide, VO 2 dioxide, is used in the production of glass coatings that block infrared radiation at certain temperatures.
A vanadium redox battery is a voltaic cell consisting of aqueous vanadium ions in various oxidation states. Batteries of this type were first proposed in the 1930s, and commercial use began in the 1980s. Vanadate can be used to protect steel from corrosion.
Vanadium is important for human health. It helps regulate carbon and lipid metabolism and is involved in energy production. It is recommended to consume 6-63 mcg per day (WHO data) of the substance from food. It is quite sufficient in cereals, legumes, vegetables, herbs, and fruits.
Vanadium(Vanadium), V, chemical element of group V of the periodic system of Mendeleev; atomic number 23, atomic mass 50.942; metal gray-steel color. Natural vanadium consists of two isotopes: 51 V (99.75%) and 50 V (0.25%); the latter is weakly radioactive (half-life T ½ = 10 14 years). Vanadium was discovered in 1801 by the Mexican mineralogist A. M. del Rio in Mexican brown lead ore and named erythronium (from the Greek erythros - red) for the beautiful red color of the heated salts. In 1830, the Swedish chemist N. G. Sefström discovered a new element in iron ore from Taberg (Sweden) and named it Vanadium in honor of the Old Norse goddess of beauty Vanadis. In 1869, the English chemist G. Roscoe obtained powdered metallic Vanadium by reducing VCl 2 with hydrogen. Vanadium has been mined on an industrial scale since the beginning of the 20th century.
The content of vanadium in the earth's crust is 1.5·10 -2% by mass; it is a fairly common element, but dispersed in rocks and minerals. Of the large number of vanadium minerals, patronite, roscoelite, decloysite, carnotite, vanadinite and some others are of industrial importance. An important source of vanadium is titanomagnetite and sedimentary (phosphorous) iron ores, as well as oxidized copper-lead-zinc ores. Vanadium is extracted as a by-product during the processing of uranium raw materials, phosphorites, bauxites and various organic deposits (asphaltites, oil shale).
Physical properties of Vanadium. Vanadium has a body-centered cubic lattice with a period a=3.0282Å. In its pure state, vanadium is malleable and can be easily worked by pressure. Density 6.11 g/cm3; melting temperature 1900°С, boiling temperature 3400°С; specific heat capacity (at 20-100°C) 0.120 cal/g deg; thermal coefficient of linear expansion (at 20-1000°C) 10.6·10 -6 deg -1; electrical resistivity at 20°C 24.8·10 -8 ohm·m (24.8·10 -6 ohm·cm); Below 4.5 K Vanadium goes into a superconducting state. Mechanical properties of high purity vanadium after annealing: elastic modulus 135.25 n/m2 (13520 kgf/mm2), tensile strength 120 n/m2 (12 kgf/mm2), elongation 17%, Brinell hardness 700 mn /m 2 (70 kgf/mm 2). Gas impurities sharply reduce the ductility of vanadium and increase its hardness and brittleness.
Chemical properties of Vanadium. At ordinary temperatures, Vanadium is not affected by air, sea water and alkali solutions; resistant to non-oxidizing acids, with the exception of hydrofluoric acid. Vanadium is significantly superior to titanium and stainless steel in terms of corrosion resistance in hydrochloric and sulfuric acids. When heated in air above 300°C, vanadium absorbs oxygen and becomes brittle. At 600-700°C Vanadium is intensively oxidized to form V 2 O 5 oxide, as well as lower oxides. When vanadium is heated above 700°C in a nitrogen stream, nitride VN is formed (bp 2050°C), stable in water and acids. Vanadium reacts with carbon at high temperatures, giving refractory carbide VC (mp 2800°C), which has high hardness.
Vanadium gives compounds corresponding to valences 2, 3, 4 and 5; Accordingly, the following oxides are known: VO and V 2 O 3 (basic in nature), VO 2 (amphoteric) and V 2 O 5 (acidic). Compounds of 2- and 3-valent vanadium are unstable and are strong reducing agents. Compounds of higher valences are of practical importance. Vanadium's tendency to form compounds of various valences is used in analytical chemistry and also determines the catalytic properties of V 2 O 5. Vanadium (V) oxide dissolves in alkalis to form vanadates.
Obtaining vanadium. To extract vanadium, the following is used: direct leaching of ore or ore concentrate with solutions of acids and alkalis; roasting of the feedstock (often with NaCl additives) followed by leaching of the roasting product with water or dilute acids. Hydrated Vanadium (V) oxide is isolated from solutions by hydrolysis (at pH = 1-3). When vanadium-containing iron ores are smelted in a blast furnace, vanadium is converted into cast iron, and when processed into steel, slag containing 10-16% V 2 O 5 is obtained. Vanadium slags are roasted with table salt. The burned material is leached with water and then with dilute sulfuric acid. V 2 O 5 is isolated from solutions. The latter is used for smelting ferrovanadium (iron alloys with 35-70% vanadium) and obtaining metallic vanadium and its compounds. Malleable metal Vanadium is obtained by the calcium-thermal reduction of pure V 2 O 5 or V 2 O 3; reduction of V 2 O 5 with aluminum; vacuum carbon-thermal reduction of V 2 O 3; magnesium-thermal reduction of VCl 3 ; thermal dissociation of vanadium iodide. Vanadium is melted in vacuum arc furnaces with a consumable electrode and in electron beam furnaces.
Application of Vanadium. Ferrous metallurgy is the main consumer of Vanadium (up to 95% of all metal produced). Vanadium is part of high-speed steel, its substitutes, low-alloy tool steels and some structural steels. With the introduction of 0.15-0.25% Vanadium, the strength, toughness, fatigue resistance and wear resistance of steel sharply increase. Vanadium introduced into steel is both a deoxidizing and carbide-forming element. Vanadium carbides, distributed in the form of dispersed inclusions, prevent grain growth when the steel is heated. Vanadium is introduced into steel in the form of a master alloy - ferrovanadium. Vanadium is also used for alloying cast iron. Vanadium's consumer is the titanium alloy industry; some titanium alloys contain up to 13% vanadium. In aviation, rocket and other fields of technology, alloys based on niobium, chromium and tantalum containing vanadium additives have found use. Various compositions of heat-resistant and corrosion-resistant alloys based on Vanadium with the addition of Ti, Nb, W, Zr and Al are being developed for use in aviation, rocket and nuclear technology. Superconducting alloys and compounds of Vanadium with Ga, Si and Ti are of interest.
Pure metallic Vanadium is used in nuclear energy (shells for fuel elements, pipes) and in the production of electronic devices. Vanadium compounds are used in the chemical industry as catalysts, in agriculture and medicine, in the textile, paint and varnish, rubber, ceramic, glass, photo and film industries.
Vanadium compounds are poisonous. Poisoning is possible by inhaling dust containing Vanadiz compounds. They cause irritation of the respiratory tract, pulmonary hemorrhages, dizziness, disturbances in the functioning of the heart, kidneys, etc.
Vanadium in the body. Vanadium is a constant component of plant and animal organisms. The source of Vanadium is igneous rocks and shales (containing about 0.013% Vanadium), as well as sandstones and limestones (about 0.002% Vanadium). In soils, Vanadium is about 0.01% (mainly in humus); in fresh and sea waters 1·10 -7 -2·10 -7%. In terrestrial and aquatic plants, the vanadium content is much higher (0.16-0.2%) than in terrestrial and marine animals (1.5·10 -5 - 2·10 -4%). Concentrators of vanadium are: the bryozoan Plumatella, the mollusk Pleurobranchus plumula, the sea cucumber Stichopus mobii, some ascidians, from molds - black aspergillus, from mushrooms - toadstool (Amanita muscaria).
