Mineral Review

What is molybdenum in simple words?

Minerals are part of human body tissues, enzymes, and hormones. They enter the human body with food and water. Chemical elements found in very small concentrations in the body are called microelements.

To microelements, necessary for the normal functioning of our body, include iron, copper, selenium, iodine, chromium, zinc, fluorine, manganese, cobalt, molybdenum, silicon, bromine, vanadium, boron.

Hardware. The body of a healthy adult man contains about 4 g of iron, a woman – 2,8 g. Most of the iron (approximately 75%) is found in the hemoglobin of red blood cells; iron is also part of myoglobin and some enzymes. The remaining 25% of iron accumulates in the reticuloendothelial system in the liver, spleen and bone marrow. Iron in foods is present in the form of heme iron, which is found in animal products (red meat and organ meats (liver, heart)), and non-heme iron, present in plant products (wheat germ, egg yolks, legumes, dried fruits (for example, dates) ) and green vegetables). The recommended daily intake of iron is 14 mg.

Copper. The copper content of the adult human body is 70–120 mg, with approximately a third of the copper distributed evenly between the liver and brain, a third found in the muscles, and the rest distributed to other tissues. The amount of copper in plant foods varies depending on the soil in which they are grown. Green leafy vegetables, legumes, whole grains and almonds, raisins and other dried fruits, meat (especially liver), and seafood (shellfish) are rich in copper.

Zinc. The adult human body contains about 2–2,5 g of zinc, with about 70% found in the bones. In a newborn, the zinc content reaches 140 mg. High zinc content is also found in the tissues of the eye, seminal vesicles, epididymis, prostate gland and sperm. Zinc is found in proteins and metalloenzymes in all blood fractions. Good sources of zinc include meat, poultry, eggs and seafood (especially oysters), grains and legumes (however, due to the presence of phytic acid in these foods, zinc is less available than that found in animal products). The recommended daily intake of zinc is 15 mg.

Cobalt mainly found in the liver, kidneys and bones. The body uses cobalt as a component of vitamin B12. Seafood, buckwheat, and vegetables (cabbage, lettuce, spinach, beet greens and watercress) are extremely rich in cobalt. The average human cobalt intake is about 0,3 mg/day. It is well absorbed, but most of it (about 0,26 mg/day) is excreted in the urine.

Molybdenum found in all tissues and fluids of the body. The adult human body contains about 9 mg of molybdenum, mainly in the liver, kidneys, adrenal glands and bones. Molybdenum is part of various enzymes and also prevents the development of caries. Dairy products, legumes, organ meats (liver, kidneys), grain products and some green leafy vegetables are rich in molybdenum.

Selenium found in all cells and tissues of the body in concentrations. The highest concentrations of selenium in the body are in the liver and kidneys. The average selenium content in an adult is about 15 mg. Selenium affects the metabolism and toxicity of some drugs and chemicals, and the toxicity of some compounds is enhanced by selenium deficiency. The level of selenium in plant foods depends on its concentration in the soil. Cereals and cereals, offal (liver and kidneys), fish (tuna), and shellfish are rich in selenium. The recommended daily intake of selenium is 0,07 mg.

Manganese. The adult human body contains about 12–20 mg of manganese. The highest concentrations of manganese are in the bones, liver and pituitary gland. Manganese concentrations are higher in tissues rich in mitochondria because manganese is concentrated in mitochondria. Manganese is a cofactor for various enzymes in the body and is also essential for normal skeletal and connective tissue development. Sources of manganese: grains, cereals, fruits, vegetables and tea.

Iodine. In the body of an adult, the total amount of iodine is 20–50 mg and is distributed as follows: muscles – 10%; leather – 10%; skeleton – 7%; thyroid gland – 20%; the remaining 13% is distributed in other endocrine organs and the central nervous system. Iodine is an integral component of thyroid hormones, which play an important role in regulating the basic metabolism of an adult, as well as the growth and development of a child. Sources of iodine include seafood, dairy products, meat and eggs, vegetables, fruits and grains grown in iodine-rich soils. The recommended daily intake of iodine is 150 mcg.

Chromium distributed throughout the human body. The total content of this mineral in the body of an adult at the age of 30 is estimated at 6–10 mg. The main role of chromium is to maintain normal glucose tolerance, and it also plays a role in lipoprotein metabolism. The best food sources of chromium are brewer’s yeast, some spices (such as black pepper), shellfish (especially oysters), eggs, processed meats, cheeses, whole grains, and unrefined brown sugar.

Fluorine. The average adult human body contains less than 1 g of fluoride, and approximately 99% of this amount is found in bones and teeth. Fluoride has a positive effect on skeletal and dental health. Sources of fluoride can be vegetables, meat, cereals, fruits, seafood, tea (an average cup of tea contains 0,1 mg of fluoride).

Silicon present in all cells of the body, its higher concentrations are found in the aorta, trachea, tendons, bones, skin and its appendages. Silicon is essential for calcification, growth and the formation of mucopolysaccharides as a cross-linking agent. Barley and oats are rich in silicon.

Bor is an integral part of the tissues of animals and people who consume plants. The adult human body contains approximately 48 mg of boron. Boron may prevent or slow osteoporosis in women over 40 by maintaining relatively high serum estrogen levels. Plant foods, especially fruits, leafy vegetables, nuts and legumes, are rich in boron. Wine, cider and beer are also high in boron.

Vanadium. The adult human body contains about 25 mg of vanadium, most of it is present in adipose tissue, blood serum, as well as in bones and teeth. Foods rich in vanadium: shellfish, mushrooms, dill seeds, black pepper and parsley. Vanadium can affect iodine metabolism and thyroid function.

Bromine. Bromine is necessary to normalize the human nervous system. Its highest concentrations are determined in the thyroid gland, kidneys and pituitary gland. The richest in bromine are legumes – beans, lentils, peas.

Dark silver metal

Molybdenum / Molybdaenum (Mo), 42

2,16 (Pauling scale)

Mo

Molybdenum – element of the secondary subgroup of the sixth group of the fifth period of the periodic system of chemical elements of D. I. Mendeleev, atomic number 42. Denoted by the symbol Mo (lat. Molybdaenum ). Simple substance Molybdenum (CAS number: 7439-98-7) is a light gray transition metal. Its main application is in metallurgy.

History and origin of the name

Discovered in 1778 by the Swedish chemist Carl Scheele, who, by calcining molybdic acid, obtained MoO3. It was first obtained in the metallic state by P. Guelm in 1782 by reducing the oxide with coal: he obtained molybdenum contaminated with carbon and molybdenum carbide. Pure molybdenum was obtained by J. Berzelius in 1817.

The name comes from ancient Greek. μόλυβδος, meaning “lead”. It is given due to the external similarity of molybdenite (MoS2), a mineral from which molybdenum oxide with a lead luster (PbS) was first isolated. Until the 18th century. Molybdenite was not distinguished from graphite and lead luster; these minerals bore the common name “molybdenum”.

Being in nature

The content in the earth’s crust is 3·10−4% by mass. Molybdenum is not found in free form. In the earth’s crust, molybdenum is distributed relatively evenly. Ultramafic and carbonate rocks contain the least molybdenum (0,4 – 0,5 g/t). Molybdenum concentration in rocks increases as SiO increases2. Molybdenum is also found in sea and river water, in plant ash, in coal and oil. The content of molybdenum in seawater ranges from 8,9 to 12,2 μg/l [2] for different oceans and water areas. What is common is that waters near the shore and the upper layers are less enriched in molybdenum than waters at depth and away from the shore. The highest concentrations of molybdenum in rocks are associated with accessory minerals (magnetite, ilmenite, sphene), but the bulk of it is contained in feldspars and less in quartz. Molybdenum in rocks is found in the following forms: molybdate and sulfide in the form of microscopic and submicroscopic precipitation, isomorphic and dispersed (in rock-forming minerals). Molybdenum has a greater affinity for sulfur than for oxygen, and tetravalent molybdenum sulfide, molybdenite, is formed in ore bodies. A reducing environment and high acidity are most favorable for the crystallization of molybdenite. Under surface conditions, predominantly oxygen compounds Mo 6+ are formed. In primary ores, molybdenite is found in association with wolframite and bismuthin, with copper minerals (porphyry copper ores), as well as with galena, sphalerite and uranium pitch (in low-temperature hydrothermal deposits). Although molybdenite is considered a stable sulfide with respect to acidic and alkaline solvents, under natural conditions, with prolonged exposure to water and atmospheric oxygen, molybdenite is oxidized and molybdenum can migrate intensively to form secondary minerals. This can explain the increased concentrations of molybdenum in sedimentary deposits – carbonaceous and siliceous-carbonaceous shales and coals.

About 20 molybdenum minerals are known. The most important of them: molybdenite MoS2 (60% Mo), powellite CaMoO4 (48% Mo), molybdite Fe(MoO4)3· nH2O (60% Mo) and wulfenite PbMoO4.

Place of Birth

Large deposits of molybdenum are known in the USA, Mexico, Chile, Canada, Australia, Norway, and Russia [3]. More than 7% of the world’s molybdenum reserves are located in Armenia [4], with 90% of them concentrated in the Kajaran copper-molybdenum deposit.

Genetic groups and industrial types of deposits

1. Contact-metasomatic (skarns)

A. High temperature (greisen)

V. quartz-chalcopyrite-molybdenite (porphyry copper ores)

Obtaining

The industrial production of molybdenum begins with the enrichment of ores by the flotation method. The resulting concentrate is fired to form MoO oxide3:

which is subjected to additional purification. Next MoO3 reduced with hydrogen:

The resulting workpieces are processed by pressure (forging, rolling, broaching).

physical properties

Molybdenum is a light gray metal with a body-centered cubic lattice of the α-Fe type (a = 3,14 Å; z = 2; space group Im3m), paramagnetic, the Mohs scale defines its hardness as 4.5 points [5]. Mechanical properties, as with most metals, are determined by the purity of the metal and previous mechanical and thermal treatment (the purer the metal, the softer it is). Has an extremely low coefficient of thermal expansion. Molybdenum is a refractory metal with a melting point of 2620 °C and a boiling point of 4639 °C.

Chemical properties

At room temperature in air, molybdenum is stable. Begins to oxidize at 400 °C. Above 600 °C it quickly oxidizes to MoO trioxide3. This oxide is also obtained by oxidation of molybdenum disulfide MoS2 and thermolysis of ammonium molybdate (NH4)6Mo7O24· 4H2O.

Mo forms molybdenum(IV) oxide MoO2 and a number of oxides intermediate between MoO3 and MoO2.

Mo forms a number of compounds with halogens in different oxidation states. When interacting with molybdenum or MoO powder3 with F2 obtain molybdenum hexafluoride MoF6, colorless, low-boiling liquid. Mo (+4 and +5) forms solid halides MoHal4 and MoHal5 (Hal = F, Cl, Br). Only molybdenum diiodide MoI is known with iodine2. Molybdenum forms oxyhalides: MoOF4, MoOCl4,MoO2F2,MoO2Cl2,MoO2Br2,MoOBr3 and others.

When molybdenum is heated with sulfur, molybdenum disulfide MoS is formed.2, with selenium – molybdenum diselenide composition MoSe2. Known molybdenum carbides Mo2C and MoC – crystalline high-melting substances and molybdenum silicide MoSi2.

A special group of molybdenum compounds is molybdenum blues. When reducing agents – sulfur dioxide, zinc dust, aluminum or others – act on slightly acidic (pH = 4) suspensions of molybdenum oxide, bright blue substances of variable composition are formed: Mo2О5·Н2Oh Mo4О11·Н2O and Mo8О238H2О.

Mo forms molybdates, salts of weak molybdic acids not isolated in the free state, xH2About UMoO3 (ammonium paramolybdate 3(NH4)2O 7MoO3zH2O; SaMoO4Fe2(MoO4)3 – found in nature). Molybdates of metals of groups I and III contain tetrahedral groups [MoO4].

When aqueous solutions of normal molybdates are acidified, MoO ions are formed3OH − , then polymolybdate ions: hepta-, (para-) Mo7О26 6−, tetra-(meta-)Mo4О13 2−, octa-Mo8О26 4− and others. Anhydrous polymolybdates are synthesized by sintering MoO3 with metal oxides.

There are double molybdates, which contain two cations at once, for example, M +1 M +3 (MoO4)2, M +1 5M +3 (MoO4)4. Oxide compounds containing molybdenum in lower oxidation states – molybdenum bronzes, for example, red K0,26MoO3 and blue K0,28MoO3. These compounds have metallic conductivity and semiconductor properties.

Application

Molybdenum is used to alloy steels, as a component of heat-resistant and corrosion-resistant alloys. Molybdenum wire (tape) is used for the manufacture of high-temperature furnaces and electric current inputs in light bulbs. Molybdenum compounds – sulfide, oxides, molybdates – are catalysts for chemical reactions, pigments for dyes, and components of glazes. Molybdenum hexafluoride is used in the deposition of metallic Mo onto various materials, MoS2 used as a solid high-temperature lubricant. Mo is included in microfertilizers. Radioactive isotopes are isotope indicators.

Molybdenum is one of the few alloying elements that can simultaneously increase the strength, toughness properties of steel and corrosion resistance. Usually, when alloying, along with an increase in strength, the fragility of the metal also increases. There are known cases of molybdenum being used in the manufacture of edged weapons in Japan in the 6th-XNUMXth centuries [XNUMX].

Molybdenum-99 is used to produce technetium-99, which is used in medicine in the diagnosis of cancer and some other diseases. The total world production of molybdenum-99 is about 12 Curies per week (based on activity on the sixth day), the cost of molybdenum-000 is $99 million per gram ($46 per 1 Ci) [470].

In 2005, world supplies of molybdenum (in terms of pure molybdenum) amounted, according to Sojitz Alloy Division, to 172,2 thousand tons (in 2003—144,2 thousand tons). Pure single-crystal molybdenum is used to produce mirrors for high-power gas-dynamic lasers. Molybdenum telluride is a very good thermoelectric material for the production of thermoelectric generators (thermo-emf with 780 μV/K). Molybdenum trioxide (molybdenum anhydride) is widely used as a positive electrode in lithium power sources.

Molybdenum is used in high-temperature vacuum resistance furnaces as heating elements and thermal insulation. Molybdenum disilicide is used as heaters in furnaces with an oxidizing atmosphere operating up to 1800 °C.

Biological role

The physiological significance of molybdenum for the animal and human body was first shown [by whom?] in 1953, with the discovery of the influence of this element on the activity of the enzyme xanthine oxidase. Molybdenum promotes (makes it more effective) the work of antioxidants, including vitamin C. An important component of the tissue respiration system. Strengthens the synthesis of amino acids, improves nitrogen accumulation. Molybdenum is part of a number of enzymes (aldehyde oxidase, sulfite oxidase, xanthine oxidase, etc.) that perform important physiological functions, in particular, the regulation of uric acid metabolism. Molybdenum enzymes catalyze the hydroxylation of various substrates. Aldehyde oxidase oxidizes and neutralizes various pyrimidines, purines, and pteridines. Xanthine oxidase catalyzes the conversion of hypoxanthines to xanthines, and xanthines to uric acid. Sulfite oxidase catalyzes the conversion of sulfite to sulfate.

A lack of molybdenum in the body is accompanied by a decrease in the content of xanthine oxidase in tissues. With a lack of molybdenum, anabolic processes suffer, and a weakening of the immune system is observed. Ammonium thiomolybdate (soluble molybdenum salt) is a copper antagonist and disrupts its utilization in the body.

Nitrogen cycle

Molybdenum is part of the active site of nitrogenase, an enzyme for fixing atmospheric nitrogen (common in bacteria and archaea).

Microelement

Micro amounts of molybdenum are necessary for the normal development of organisms; it is used as part of microelement nutrition, in particular, for berry crops.

Affects reproduction (in plants).

Price

As of 2012, the cost of molybdenum is about $32 per ton [500].

Physiological action

Dust from molybdenum and its compounds irritates the respiratory tract.

См. также

  • Spinifex Ridge is the largest molybdenum deposit in Australia.
  • The Kajaran copper-molybdenum deposit is the largest molybdenum deposit in the territory of the former USSR.

Notes

  1. Editorial team: Knunyants I. L. (chief editor) Chemical encyclopedia: in 5 volumes – Moscow: Soviet Encyclopedia, 1992. – T. 3. – P. 125. – 639 p. — 50 copies. — ISBN 000—5—85270—039
  2. JP Riley and Skirrow G. Chemical Oceanography V. 1, 1965
  3. Molybdenum in the Chemical Encyclopedia
  4. Results of activities of Zangezur Copper-Molybdenum Combine CJSC (Armenia) in the first quarter of 2005.
  5. Povarennykh A.S. Hardness of minerals. – Academy of Sciences of the Ukrainian SSR, 1963. – P. 197-208. — 304 p.
  6. Gurevich Yu. G. The mystery of the damask pattern. – M.: Knowledge, 1985. – 192 p. pp. 15 – 19.
  7. Molybdenum-99 – current state of affairs. Report from the USA
  8. Exchange prices for molybdenum – Metal Torg.Ru – news, analytics and prices: rolled metal, ferrous and non-ferrous metals, scrap, steel, hardware, fittings, beams, pipes, channels, sheets, carbon.

references

Molybdenum on Wikimedia Commons?
  • Molybdenum at the Popular Library of Chemical Elements
  • Molybdenum at Webelements
  • Molybdenum-99 began to be produced in Dimitrovgrad
  • Production of molybdenum-99 has begun in the Ulyanovsk region
Alkali metals Alkaline earth metals Lanthanides Actinoids Transition metals Other metals Metalloids Other non-metals Halogens Noble gases

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