Molybdenum and its alloys are refractory materials. For the manufacture of shells for the warheads of missiles and aircraft, refractory metals and alloys based on them are used in two versions. In one embodiment, these metals serve only as heat shields, which are separated from the main structural material by thermal insulation. In the second case, refractory metals and their alloys serve as the main structural materials. Molybdenum ranks second after tungsten and its alloys in terms of strength properties. However, in terms of specific strength at temperatures below 1350-1450°C, Mo and its alloys take first place. Thus, molybdenum and niobium and their alloys, which have greater specific strength up to 1370°C compared to tantalum, tungsten and alloys based on them, are most widely used for the manufacture of skins and frame elements of missiles and supersonic aircraft.

Mo is used to make honeycomb panels in spacecraft, heat exchangers, the shells of rockets and capsules returning to earth, heat shields, wing edge skins, and stabilizers in supersonic aircraft. Some parts of ramjet and turbojet engines (turbine blades, tail skirts, nozzle flaps, rocket engine nozzles, control surfaces in rockets with solid fuel) operate under very difficult conditions. At the same time, the material requires not only high resistance to oxidation and gas erosion, but also high long-term strength and impact resistance. At temperatures below 1370°C, molybdenum and its alloys are used to manufacture these parts.

Molybdenum is a promising material for equipment operating in sulfuric, hydrochloric and phosphoric acid environments. Due to the high resistance of this metal in molten glass, it is widely used in the glass industry, in particular for the manufacture of electrodes for glass melting. Currently, molybdenum alloys are used to make molds and cores for injection molding machines for aluminum, zinc and copper alloys. The high strength and hardness of such materials at elevated temperatures have led to their use as a tool in hot forming of steels and alloys (piercing mill mandrels, dies, press dies).

Molybdenum significantly improves the properties of steels. The Mo additive significantly increases their hardenability. Small additions of Mo (0.15-0.8%) to structural steels increase their strength, toughness and corrosion resistance so much that they are used in the manufacture of the most critical parts and products. To increase hardness, molybdenum is introduced into alloys of cobalt and chromium (stellites), which are used for surfacing the edges of parts made of ordinary steel subject to wear (abrasion). It is also part of a number of acid-resistant and heat-resistant alloys based on nickel, cobalt and chromium.

Another area of ​​application is the production of heating elements for electric furnaces operating in a hydrogen atmosphere at temperatures up to 1600°C. Molybdenum is also widely used in the electronics industry and X-ray engineering for the manufacture of various parts of electron tubes, X-ray tubes and other vacuum devices.

Molybdenum compounds - sulfide, oxides, molybdates - are catalysts for chemical reactions, dye pigments, and components of glazes. Also, this metal as a microadditive is included in fertilizers. Molybdenum hexafluoride is used in the deposition of metallic Mo onto various materials. MoSi 2 is used as a solid high-temperature lubricant. Pure single-crystal Mo 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. MoS 2 disulfide and molybdenum diselenide MoSe 2 are used as a lubricant for rubbing parts operating at temperatures from -45 to +400°C. In the paint and varnish and light industries, a number of Mo chemical compounds are used as pigments for the production of paints and varnishes and for dyeing fabrics and furs.

Molybdenum

MOLYBDENUM[de], -a; m.[lat. Molybdaenum] Chemical element (Mo), a hard, refractory metal with a silvery-white luster (used in the electrical industry and in the form of alloys in mechanical engineering). Molybdenum wire.

◁ Molybdenum, oh, oh. M ores. Mth steel. Mth wire.

molybdenum

(lat. Molybdaenum), chemical element of group VI of the periodic table. The name comes from the Greek mólybdos - lead (based on the similarity of the minerals Mo and Pb). Light gray metal, density 10.2 g/cm 3 , t pl 2623°C. Chemically resistant (oxidizes in air at temperatures above 400°C). The main mineral is molybdenite. More than 75% of molybdenum is used for alloying cast irons and steels used in the aircraft and automotive industries, in the manufacture of turbine blades, etc. Heat-resistant (for jet engines) and acid-resistant (chemical industry apparatus) alloys are very promising; Thus, the Fe-Ni-Mo alloy is resistant to all acids (except HF) up to 100°C. An important structural material in the production of filaments for electric lamps and cathodes for electric vacuum devices. Oxides MoO 2, MoO 3 are catalysts for petrochemical and other processes.

MOLYBDENUM

MOLYBDENUM (lat. Molibdaenum), Mo (read “molybdenum”), chemical element with atomic number 42, atomic mass 95.94. Natural molybdenum consists of seven stable isotopes: 92 Mo (15.86% by weight), 94 Mo (9.12%), 95 Mo (15.70), 96 Mo (16.50%), 97 Mo (9. 45%), 98 Mo (23.75) and 100 Mo (9.62% by weight). Configuration of two outer electronic layers 4 s 2 p 6 d 5 5s 1 . Oxidation states from +2 (valence II) to +6 (VI) are the most characteristic. Located in group VIB in the 5th period of the periodic table of elements.
The radius of the atom is 0.140 nm, the radius of the Mo 3+ ion is 0.083 nm, the Mo 4+ ion is 0.079 nm, the Mo 5+ ion is 0.075 nm, the Mo 6+ ion is from 0.055 nm (coordination number 4) to 0.087 (7). The sequential ionization energies are 7.10, 16.15, 27.13, 40.53, 55.6 and 71.7 eV. Electron work function 4.3 eV. Electronegativity according to Pauling (cm. PAULING Linus) 1,8.
History of discovery
Discovered in 1778 by the Swedish chemist K. Scheele (cm. SCHEELE Karl Wilhelm), who, by calcining molybdic acid, obtained the oxide MoO 3. By reducing it with coal, he obtained molybdenum. This metal was contaminated with coal and molybdenum carbide. Pure molybdenum was obtained by J. Berzelius in 1817 (cm. BERZELIUS Jens Jacob). The name of the element comes from the Greek. “molyubdos” - lead, since the mineral - molybdenum luster - is similar in appearance to lead and its mineral - lead luster
Being in nature
The content in the earth's crust is 3·10 -4% by weight. Molybdenum is not found in free form. About 20 molybdenum minerals are known. The most important of them: molybdenite (cm. MOLYBDENITE) MoS 2, powellite (cm. POWELLITE) CaMoO 4, molybdite Fe(MoO 4) 3 .nH 2 O and wulfenite (cm. WULFENITE) PbMoO4.
Receipt
The industrial production of molybdenum begins with the enrichment of ores by the flotation method. The resulting concentrate is fired until the oxide MoO 3 is formed:
2MoS 2 + 7O 2 = 2MoO 3 + 4SO 2,
which is subjected to additional purification. Next, MoO 3 is reduced by H 2 . The resulting workpieces are processed by pressure (forging, rolling, broaching).
Physical and chemical properties
Molybdenum is a light gray metal with a cubic body-centered lattice of the a-Fe type, A= 0.314 nm. Melting point 2623°C, boiling point 4800°C, density 10.2 kg/dm3. Paramagnetic Mechanical properties are determined by the purity of the metal and previous mechanical and heat treatment.
At room temperature in air, Mo is stable. Begins to oxidize at 400°C. Above 600°C it quickly oxidizes to MoO 3 trioxide. This oxide is also obtained by the oxidation of molybdenum disulfide MoS 2 and the thermolysis of ammonium molybdate (NH 4) 6 Mo 7 O 24 .4H 2 O.
Mo has molybdenum(IV) oxide MoO2 and a number of oxides intermediate between MoO3 and MoO2.
With halogens (cm. HALOGEN) Mo forms a number of compounds in different oxidation states. When molybdenum powder or MoO 3 reacts with F 2, molybdenum hexafluoride MoF 6, a colorless, low-boiling liquid, is obtained.
Mo (+4 and +5) forms solid halides MoHal 4 and MoHal 5 (Hal = F, Cl, Br). Only molybdenum diiodide MoI 2 is known with iodine.
Mo forms oxyhalides: MoOF 4, MoOCl 4, MoO 2 F 2, MoO 2 Cl 2, MoO 2 Br 2, MoOBr 3 and others.
When molybdenum is heated with sulfur (cm. SULFUR) molybdenum disulfide MoS 2 is formed, with selenium (cm. SELENIUM)- molybdenum diselenide composition MoSe 2. Molybdenum carbides Mo 2 C and MoC are known - crystalline high-melting substances and molybdenum silicide MoSi 2.
A special group of molybdenum compounds - molybdenum blues (cm. MOLYBDATES). When sulfur dioxide, zinc dust, aluminum or other reducing agents act on slightly acidic (pH 4) suspensions of molybdenum oxide, bright blue substances of variable composition are formed: Mo 2 O 5 H 2 O, Mo 4 O 11 H 2 O and Mo 8 O 23 8H 2 O.
Mo forms molybdates, salts of weak molybdic acids not isolated in the free state, X H 2 O at MoO 3 (ammonium paramolybdate 3(NH 4) 2 O 7MoO 3 z H2O; CaMoO 4, Fe 2 (MoO 4) 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 3 OH – ions are formed, then polymolybdate ions: hepta-, (para-) Mo 7 O 26 6-, tetra-(meta-) Mo 4 O 13 2-, octa-Mo 8 O 26 4- and others. Anhydrous polymolybdates are synthesized by sintering MoO 3 with metal oxides.
There are double molybdates, which contain two cations at once, for example, M +1 M +3 (MoO 4) 2, M +1 5 M +3 (MoO 4) 4. Oxide compounds containing molybdenum in lower oxidation states are molybdenum bronzes, for example, red K 0.26 MoO 3 and blue K 0.28 MoO 3. 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 heaters for high-temperature furnaces and electric current inputs in light bulbs. Molybdenum compounds - sulfide, oxides, molybdates - are catalysts for chemical reactions, dye pigments, and components of glazes. Molybdenum hexafluoride is used when applying metal Mo to various materials. MoSi 2 is used as a solid high-temperature lubricant. Mo is included in microfertilizers. Radioactive isotopes 93 Mo (T 1/2 6.95 h) and 99 Mo (T 1/2 66 h) are isotopic indicators.
Physiological significance
Micro amounts of Mo are necessary for normal plant development.

encyclopedic Dictionary. 2009 .

Synonyms:

See what “molybdenum” is in other dictionaries:

- (Greek molibdaine, from molybdos lead). A whitish metal found in molybdenite in combination with sulfur. Dictionary of foreign words included in the Russian language. Chudinov A.N., 1910. MOLYBDENUM is a shiny brittle metal; beat V. = 9.01; solution... Dictionary of foreign words of the Russian language

MOLYBDENUM- MOLYBDENUM, chem. element, symbol Mo, serial number 42, at. weight 96.0; stands in the 6th group of the periodic table. Natural compounds of M.: molybdenum luster MoS2 and yellow lead ore PbMo04. M is obtained from MoS2 by firing and subsequent... ... Great Medical Encyclopedia

- (symbol Mo), silvery white TRANSITION CHEMICAL ELEMENT, metal first discovered in 1778. Extracted from ores containing MOLYBDENITE (MoS2). The concentrated mineral is roasted to produce molybdenum trioxide, which is mixed with iron... Scientific and technical encyclopedic dictionary

- (Latin Molybdaenum), Mo, chemical element of group VI of the periodic table, atomic number 42, atomic mass 95.94; metal, melting point 2623 shC. Molybdenum is used for alloying steels, as a component of heat-resistant alloys in aviation, rocket and... ... Modern encyclopedia

Mo (Latin Molybdaenum, from Greek molybdos lead * a. molybdenum; n. Molybdan; f. molybdene; i. molybdeno), chemical. element of group VI periodic. Mendeleev system, at. n. 42, at. m. 95.94. In natural M. there are seven stable isotopes; 92Mo (15.86%) ... Geological encyclopedia

Molybdenum- (Latin Molybdaenum), Mo, chemical element of group VI of the periodic table, atomic number 42, atomic mass 95.94; metal, melting point 2623 °C. Molybdenum is used for alloying steels, as a component of heat-resistant alloys in aviation, rocket and... ... Illustrated Encyclopedic Dictionary

- (lat. Molybdaenum) Mo, chemical element of group VI of the periodic system, atomic number 42, atomic mass 95.94. The name is from the Greek molybdos lead (based on the similarity of the minerals Mo and Pb). Light gray metal, density 10.2 g/cm³, melting point 2623.C.... ... Big Encyclopedic Dictionary

- [de], molybdenum, husband. (from Greek molybdos lead) (chemical). The chemical element is a hard metal with a white sheen. Ushakov's explanatory dictionary. D.N. Ushakov. 1935 1940 … Ushakov's Explanatory Dictionary

- [de], ah, husband. The chemical element is a hard, shiny, silvery-white metal. | adj. molybdenum, oh, oh. Ozhegov's explanatory dictionary. S.I. Ozhegov, N.Yu. Shvedova. 1949 1992 … Ozhegov's Explanatory Dictionary

- (Molybdenum), Mo, chemical. element of the secondary subgroup of group VI non-riodic. systems of elements, at. number 42, at. mass 95.94. In nature it is represented by 7 stable isotopes: 92Mo (14.84%), 94Mo (9.25%), 95Mo (15.92%), 96Mo (16.68%), 97Mo (9.55%), 98Mo... ... Physical encyclopedia

Noun, number of synonyms: 2 metal (86) element (159) ASIS Dictionary of Synonyms. V.N. Trishin. 2013… Synonym dictionary

Molybdenum (Latin Molybdenum, symbol Mo) is an element with atomic number 42 and atomic weight 95.94. It is an element of a secondary subgroup of the sixth group, the fifth period of the periodic table of chemical elements of Dmitry Ivanovich Mendeleev. Together with chromium and tungsten, molybdenum forms a subgroup of chromium. The elements of this subgroup are distinguished by the fact that their outer electronic layer of atoms contains one or two electrons, this determines the metallic nature of these elements and their difference from the elements of the main subgroup. Under normal conditions, molybdenum is a transitional refractory (melting point 2620 °C) light gray metal with a density of 10.2 g/cm3. In many ways, the mechanical properties of molybdenum depend on the purity of the metal and its previous mechanical and thermal treatment.

There are 31 known isotopes of molybdenum from 83Mo to 113Mo. Stable are: 92Mo, 94Mo – 98Mo. In nature, the forty-second element is represented by seven isotopes: 92Mo (15.86%), 94Mo (9.12%), 95Mo (15.70%), 96Mo (16.50%), 97Mo (9.45%), 98Mo (23.75%) and 100Mo (9.62%) with half-life = 1.00 1019 years. The most unstable isotopes of element No. 42 have half-lives less than 150 ns. Radioactive isotopes 93Mo (half-life 6.95 hours) and 99Mo (half-life 66 hours) are isotopic indicators.

Molybdenum in the form of the mineral molybdenite (molybdenum disulfide - MoS2) was known to the ancient Greeks and Romans for a very long time. For many centuries, molybdenite, or molybdenum luster as it is also called, was not distinguished from galena (lead luster PbS) and graphite. The fact is that all these minerals are very similar in appearance, in addition, they are all capable of leaving a mark on paper. Therefore, until the 18th century, these minerals were called the same: “Molybdaena”, which means “lead” in Greek.

The first to suggest that all three of these minerals are independent substances was the Swedish chemist F. Kronstedt. 20 years later, another Swedish chemist, K. Scheele, began researching molybdenite. Having dissolved the mineral in concentrated nitric acid, he obtained a white precipitate, which he called molybdic acid. Assuming that the metal could be obtained by calcining this white precipitate with pure coal, but not having the necessary equipment (furnace), Scheele suggested that another chemist, Gjelm, who had such a furnace, conduct the experiment. The result of the experiment was the production of molybdenum carbide, which both scientists accepted as a metal, which they called molybdenum. J. Ya. Berzelius was destined to obtain a relatively pure metal, establish its atomic weight and describe some of its properties.

Most of the mined molybdenum (80-85%) is consumed as an alloying element in the production of special grades of steel. Molybdenum is a component of many stainless steels; in addition, the addition of this element helps to increase the heat resistance of these steels. Alloys alloyed with the forty-second element are used in aviation, rocket and nuclear technology, and chemical engineering. In its pure form, the metal is used in the manufacture of parts for electronic lamps and incandescent lamps (anodes, grids, cathodes, filament holders, etc.), molybdenum wire and tape are used as heaters for high-temperature furnaces. Some compounds of the forty-second element have also found widespread use. Thus, molybdenum anhydride is widely used as a positive electrode in lithium power sources, MoS2 is a lubricant for rubbing parts of mechanisms, and some molybdenum oxides are catalysts in the chemical and oil industries.

Scientists have found that molybdenum is constantly present in the body of plants, animals and humans as a trace element, participating primarily in nitrogen metabolism. The forty-second element is necessary for the activity of a number of redox enzymes necessary for metabolic processes in plants and animals.

Biological properties

The forty-second element is one of the most important microelements in the nutrition of humans, animals and plants; it is necessary for the normal development and growth of organisms, and affects reproduction in plants. The molybdenum content in the green mass of plants is about 1 mg per kilogram of dry matter. This element is necessary for the activity of a number of redox enzymes (flavoproteins), which catalyze the reduction of nitrates and nitrogen fixation in plants (there is a lot of molybdenum in legume nodules, common in bacteria and archaea). In addition, in plants, the forty-second element stimulates the biosynthesis of nucleic acids and proteins, increases the content of chlorophyll and vitamins.

With a lack of molybdenum, tomatoes, legumes, oats, lettuce and other plants develop a special type of spotting, do not bear fruit and die. For this reason, it is necessary to introduce soluble molybdates in small quantities into microfertilizers. Thus, in one of the experimental farms in New Zealand it was found that introducing small doses of molybdenum salts into the soil increases the yield of clover and alfalfa by about a third. Further agricultural studies showed that microquantities of molybdenum enhance the activity of nodule bacteria, as a result of which plants absorb nitrogen better. It was also found that molybdenum is best absorbed on acidic soils, and on red soils and brown soils rich in iron, the effectiveness of molybdenum is minimal.

The physiological effect of molybdenum on animal and human organisms was first established in 1953, with the discovery of the effect of this element on the activity of the enzyme xanthine oxidase. Molybdenum makes the work of antioxidants, including vitamin C, more effective, and it is also an important component of the tissue respiration system, enhances the synthesis of amino acids, and improves the accumulation of nitrogen. The forty-second element is a component of a number of enzymes (xanthine oxidase, aldehyde oxidase, sulfite oxidase, etc.) that perform important physiological functions, in particular, the regulation of uric acid metabolism. A lack of molybdenum in the body is accompanied by a decrease in the content of xanthine oxidase in tissues, as a result of which anabolic processes “suffer” and a weakening of the immune system is observed.

It is not absolutely certain, but it is assumed that molybdenum plays an important role in the process of incorporating fluoride into tooth enamel, as well as in stimulating hematopoiesis. When there is a lack of molybdenum in the body of animals, the ability to oxidize xanthine to uric acid is impaired, the excretion of uric acid and inorganic sulfates is reduced, and the growth rate is reduced. Animals form xanthine kidney stones. Molybdenum deficiency can lead to decreased breakdown of cellulose and excessive accumulation of copper in the body, leading to copper intoxication. All these phenomena can be eliminated by adding molybdenum to the diet. In humans, molybdenum deficiency manifests itself in the form of hypouricemia, hypermethioninemia, hyperoxypurinemia, hypouricosuria and hyposulfaturia, progressive mental disorders (up to coma).

It has been established that compounds of the forty-second element enter the body with food. During the day, 75-250 mcg of molybdenum enters the body of an adult with food, which is the required daily intake of this microelement. Molybdenum supplied with food in the form of soluble complexes is easily absorbed - 25-80% of the element supplied with food is absorbed into the human gastrointestinal tract. Further, approximately 80% of molybdenum entering the blood binds to proteins (primarily albumin) and is transported throughout the body. The concentrators of the forty-second element are the liver and kidneys. Molybdenum is excreted mainly in urine and bile. Molybdenum does not accumulate in the body of mammals. The main suppliers of molybdenum to the body are dried beans, milk and dairy products, organ meats, cruciferous vegetables, gooseberries, black currants, cereals and baked goods. Despite the fact that molybdenum is a rare element, cases of its deficiency in the human body are rare.

Excess molybdenum in the body leads to metabolic disorders and delayed bone growth. Xanthine oxidase accelerates nitrogen metabolism in the body, in particular purine metabolism. As a result of the breakdown of purines, uric acid is formed. If there is too much of this acid, then the kidneys do not have time to remove it from the body, and salts dissolved in this acid accumulate in the joints and muscle tendons. The joints begin to ache and gout develops. An excess of molybdenum in the feed of ruminants leads to chronic molybdenum toxicosis, accompanied by diarrhea, exhaustion, and impaired metabolism of copper and phosphorus. To reduce the toxic effect of molybdenum on the body, it is necessary to reduce the intake of molybdenum-rich foods, carry out symptomatic treatment, and use those drugs and dietary supplements that contain copper, as well as sulfur (methionine, unithiol, sodium thiosulfate, etc.).

It turns out that molybdenum can influence the body not only directly - as an important trace element, but also indirectly - as a soil component. So, in the north of China there is a place called Lin Xian, it is located in Honan province. This place is known as the area with the highest incidence of esophageal cancer among the local population. What is the reason for this anomaly? The answer was provided by careful soil testing. It turned out that the lands of Lin Xian are poor in the forty-second element, the presence of which is necessary for the normal functioning of nitrogen-fixing bacteria. The fact is that the restoration of nitrates introduced into the soil is carried out by them using the molybdenum-dependent enzyme nitrate reductase. A lack of molybdenum reduces the activity of the enzyme, which is only enough to reduce nitrate not to ammonia, but to nitrosamines, which are known to have high carcinogenic activity. The application of molybdenum fertilizers to the soil significantly reduced the incidence of disease in the population. Similar endemic diseases have been recorded in South Africa.

It is interesting that the molybdenum mine, developed in the 30s of the 20th century and located on one of the spurs of the Takhtarvumchorr ridge (Kola Peninsula), is now a frequently visited tourist route. The mine has only one horizon, which has three entrances at an altitude of 600 meters above sea level. A little below the entrance to the adit there is a steam engine, which once supplied steam through pipes to the miners' jackhammers. By the way, both the steam engine and the supply pipes have been preserved. The route is short, about three kilometers of drifts, and part of the mine is flooded.

Mysterious spirals made of tungsten, molybdenum and copper are a controversial and not completely explained by modern science phenomenon in the form of small (from 3 microns to 3 mm) objects discovered in the Subpolar Urals. The first such finds appeared in 1991, during geological exploration, which was carried out in the area of ​​the Naroda River in sand samples examined for the presence of gold. Later, similar finds were repeatedly found in the Subpolar Urals in the area of ​​the Naroda, Kozhim and Balbanyu rivers, as well as in Tajikistan and Chukotka. What makes the finds unusual is their age. Dating the objects is very difficult due to the fact that most of them were discovered in alluvial deposits.

An exception are two finds made in 1995 in the wall of a quarry in the area of ​​the lower reaches of the Balbanyu River. Examinations of the rocks in which molybdenum springs were found gave a vague result - from 20,000 to 318,000 years! Many hypotheses have been put forward regarding these findings: the spirals are of alien origin and may be a product of extraterrestrial nanotechnology brought to Earth several thousand years ago; mysterious springs are artificial objects, but not ancient, but modern, fallen into rocks from the surface of the earth. The generally accepted theory is the opinion of Nikolai Rumyantsev, Doctor of Geological and Mineralogical Sciences, Honored Geologist of Russia, about the natural origin of “springs” - a form of native tungsten.

Molybdenum is not a coin metal, however, the likes of “coins” (they do not have a face value) or medallions are sold by the company “Metallium”, there are other medals-tokens sold by manufacturing companies (they also mine the metal) of molybdenum.

Another fantastic hypothesis indirectly related to molybdenum is the version of the extraterrestrial origin of life on Earth. One of the arguments of this theory: “the presence of extremely rare elements in terrestrial organisms means that they are of extraterrestrial origin.” Molybdenum is found in the earth's crust in small quantities, but its role in the metabolism of earthly organisms is significant. At the same time, it is noted that so-called “molybdenum stars” with a high molybdenum content are known, which are the original “plantations” of microorganisms brought to Earth!

However, this phenomenon can be explained from the perspective of evolutionary biochemistry, for example, the earth’s crust contains very little phosphorus, and phosphorus is an essential component of nucleic acids, which, along with proteins, are essential for life; in addition, higher nervous activity is also very closely related to phosphorus. In addition, the Japanese scientist Yegani determined that the total content of molybdenum on Earth is indeed low, but its percentage in sea water is twice as high as that of chromium. On this subject, Yegani writes: “The relative abundance of this element in seawater confirms the widely accepted view that life on Earth originated in a primordial ocean.”

Story

Even the ancient Greeks noticed that some minerals can leave a gray mark on paper. Based on this fact, they combined a number of substances with completely different properties under one name - “Molybdaena”, which translated from Greek means lead, which itself is quite capable of writing on paper. The similarity of lead-gray molybdenite to galena and graphite is also to blame for this confusion. The softness of these minerals allowed them to be used as pencil leads, although if you look closely, the molybdenum sheen leaves a greenish-gray color on paper, unlike the gray color of graphite or lead sheen. These factors, plus the similarity of the Greek names for lead “ó” and galena “o”, became the reason for the misconception about the similarity of the three minerals (PbS - galena, MoS2 - molybdenite and graphite) from ancient times smoothly migrated to the Middle Ages. This situation continued until the 18th century.

The first who wanted to break the “vicious circle” was the famous Swedish chemist and mineralogist Axel Fredrik Cronstedt (1722-1765). In 1758, he suggested that in fact graphite, molybdenite (MoS2 - molybdenum luster) and galena (PbS - lead luster) are three completely independent substances. However, on this assumption the progress towards the truth was completed.

Only twenty years later - in 1778 - did people again become interested in the chemical composition of molybdenite. And again it was a Swedish chemist - Karl Wilhelm Scheele. The first thing Scheele did was to boil molybdenum luster in concentrated nitric acid, as a result of which the chemist obtained a white precipitate of “special white earth” (Wasserbleyerde). He named this earth molybdic acid (Acidum Molybdaenae). In the time of Karl Wilhelm, “earths” were called anhydrides, that is, the combination of an element with oxygen, in other words, “acid minus water.” The lack of this knowledge did not prevent the scientist from suggesting that metal from the “earth” could be obtained by calcining the latter with pure coal. However, lacking the necessary equipment (Scheele did not have a suitable furnace), the scientist was unable to conduct the experiment on his own.

Devoted only to science, Scheele, without any feelings of envy, in 1782 sent a sample of molybdic acid to another Swedish chemist, Peter Jacob Hjelm. In turn, he finally manages to restore it with coal and obtain a metal core (smelted metal obtained by fusing a mineral or ore with soda or other fluxes). However, it was only highly contaminated molybdenum carbide. The fact is that when molybdenum trioxide MoO3 is calcined with coal, it is impossible to obtain pure molybdenum, because it reacts with coal to form carbide. Nevertheless, the scientists rejoiced. Scheele congratulated his colleague: “I am glad that we now have the metal molybdenum.” Thus, in 1790, the new metal received a foreign name, because the Latin molibdaena comes from the ancient Greek name for lead - μολνβδος. This is a well-known paradox - after all, it is difficult to find metals more dissimilar than molybdenum and lead.

Relatively pure metal was obtained only in 1817 - after the death of both discoverers. The honor of this discovery belongs to another famous Swedish chemist, Jens Jakob Berzelius. He reduced molybdenum anhydride not with coal, but with hydrogen and obtained truly pure molybdenum, established its atomic weight and studied its properties in detail.

Molybdenum of industrial purity was obtained only at the beginning of the 20th century.

Being in nature

According to various sources, the content of molybdenum in the earth's crust ranges from 1.1∙10-4% to 3∙10-4% by mass. Molybdenum is not found in free form; in general, the forty-second element is poorly distributed in nature. According to the classification of the Soviet geochemist V.V. Shcherbina, elements are considered rare if they are less than 0.001% in the earth’s crust, therefore, molybdenum is a typical rare element. However, the forty-second element is distributed relatively evenly. About twenty molybdenum minerals are known in nature, most of them (various molybdates) are formed in the biosphere. Ultrabasic and carbonate rocks contain the least molybdenum (0.4 - 0.5 g/t).

It is noted that the concentration of molybdenum in rocks increases as SiO2 increases, because in magmatic processes molybdenum is associated mainly with acidic magma and granitoids. The accumulation of molybdenum is associated with deep hot waters, from which it precipitates in the form of molybdenite MoS2, forming hydrothermal deposits. The most important precipitant of the forty-second element from water is H2S. Molybdenum is found in sea and river water, plant ash, coal and oil. Moreover, the content of the forty-second element in sea water ranges from 8.9 to 12.2 μg/l - depending on the ocean and water area. The only general phenomenon that can be considered is that the waters near the shore and surface layers are much poorer in molybdenum than the deep layers of the ocean. The waters of the oceans and seas contain more of the forty-second element than river waters. The fact is that, coming with river runoff, molybdenum partially accumulates in sea water, and partially precipitates, concentrating in clayey silts.

The most important molybdenum minerals are molybdenite (MoS2), powellite (CaMoO4), molybdo-scheelite (Ca(Mo,W)O4), molybdite (xFe2O3 yMoO3 zH2O) and wulfenite (PbMoO4). Molybdenite or molybdenum luster is a mineral from the sulfide class (MoS2), it contains 60% molybdenum and 40% sulfur. A small amount of rhenium is also detected - up to 0.33%. Most often, this mineral is found in greisen, less often pegmatite deposits, in which it is associated with wolframite, cassiterite, topaz, fluorite, pyrite, chalcopyrite and other minerals. The most important accumulations of molybdenite are associated with hydrothermal formations, especially widespread in quartz veins and silicified rocks.

The average molybdenum content in ores of large deposits is 0.06-0.3%, small ones - 0.5-1%. As an associated component, the forty-second element is extracted from other ores when their molybdenum content is 0.005% or higher. In addition, molybdenum ores are distinguished by the mineral composition and shape of the ore bodies. According to the last criterion, they are divided into skarn (molybdenum, tungsten-molybdenum and copper-molybdenum), vein (quartz, quartz-sericite and quartz-molybdenite-wolframite) and veinlet-disseminated (copper-molybdenum, quartz-molybdenite-sericite, copper porphyry with molybdenum). Previously, quartz vein deposits were of primary industrial importance, but in modern times they have almost all been worked out. Therefore, veinlet-disseminated and skarn deposits have acquired paramount importance.

More recently, the United States of America was rightfully considered the world leader in reserves and production of molybdenum ores, where molybdenum-containing ores are mined in Colorado, New Mexico, Idaho and a number of other states. However, recent discoveries of new rich deposits have put China in the lead, with seven major provinces involved in production. Although the United States still remains the leader in molybdenum production, China's booming economy may soon propel this country into first place in the production of the forty-second element. Other countries with large reserves of molybdenum ores include: Chile, Canada (British Columbia territory), Russia (seven developed deposits), Mexico (La Caridad deposit), Peru (Tokepala mine), many CIS countries, etc.

Application

The main consumer of molybdenum (up to 85%) is metallurgy, where the lion's share of the mined forty-second element is spent on producing special structural steels. Molybdenum significantly improves the properties of alloyed metals. The addition of this element (0.15-0.8%) significantly increases hardenability, improves strength, toughness and corrosion resistance of structural steels, which are used in the manufacture of the most critical parts and products.

Molybdenum and its alloys are refractory materials, and this quality is simply necessary in the manufacture of the lining of the head parts of missiles and aircraft. Moreover, the use of such alloys is possible both as an auxiliary material - heat shields separated from the main material by thermal insulation, and as the main structural material. Although molybdenum is inferior to tungsten and its alloys in terms of strength characteristics, in terms of specific strength at temperatures below 1,350-1,450 °C, molybdenum and its alloys take first place, and titanium-molybdenum alloys have a service temperature limit of 1,500 °C!

It is because of this that molybdenum and niobium, as well as their alloys, which have greater specific strength up to 1,370 °C compared to tantalum, tungsten and alloys based on them, are most widely used in the manufacture of skins and frame elements of missiles and supersonic aircraft. Heat-resistant steels alloyed with the forty-second element are used to make the shells of rockets and capsules returning to earth, honeycomb panels of spacecraft, heat shields, heat exchangers, skins on the edges of wings and stabilizers in supersonic aircraft. In addition, molybdenum is used in steels intended for some parts of ramjet and turbojet engines (nozzle flaps, turbine blades, tail skirts, rocket engine nozzles, control surfaces in rockets with solid fuel). Materials operating in these conditions require not only high resistance to oxidation and gas erosion, but also high long-term strength and impact resistance. All these indicators at temperatures below 1,370 °C are met by molybdenum and its alloys.

Molybdenum and its alloys are used in parts that operate for a long time in a vacuum, as a structural material in nuclear power reactors, for the manufacture of equipment operating in aggressive environments (sulfuric, hydrochloric and phosphoric acids). To increase hardness, molybdenum is introduced into alloys of cobalt and chromium (stellites), which are used for surfacing the edges of parts made of ordinary steel subject to wear (abrasion). Since molybdenum and its alloys are stable in molten glass, it is widely used in the glass industry, for example, for the manufacture of electrodes for glass melting. Currently, molybdenum alloys are used to make molds and cores for injection molding machines for aluminum, zinc and copper alloys. A molybdenum tungsten alloy paired with pure tungsten is used to measure temperatures up to 2,900 °C in a reducing atmosphere.

In its pure form, molybdenum is used in the form of tape or wire as heating elements in high-temperature (up to 2,200 °C) induction furnaces. Molybdenum tin and wire are widely used in the radio-electronic industry (as a material for the anodes of radio tubes) and X-ray technology for the manufacture of various parts of electron tubes, X-ray tubes and other vacuum devices.

Numerous compounds of the forty-second element have also found widespread use. MoS2 disulfide and molybdenum diselenide MoSe2 are used as lubricants for rubbing parts operating at temperatures from -45 to +400 °C. In addition, molybdenum disulfide is added to engine oil, where it forms layers on metal surfaces that reduce friction. Molybdenum hexafluoride is used when applying molybdenum metal to various materials. Molybdenum disilicide MoSi2 is used in the manufacture of heaters for high-temperature furnaces, Na2MoO4 is used in the production of paints and varnishes. Molybdenum telluride is a very good thermoelectric material for the production of thermoelectric generators. Many compounds of the forty-second element (sulfides, oxides, molybdates) are good catalysts for chemical reactions, and are also included in pigment dyes and glazes.

Production

Initially, molybdenum ores are enriched, for which a flotation method is used, based on the different surface wettability of minerals with water. Finely ground ore is treated with water with the addition of a small amount of flotation reagent, which enhances the difference in wettability between the particles of the ore mineral and the gangue. Air is intensively blown through the resulting mixture; at the same time, its bubbles stick to the grains of those minerals that are less wetted. These minerals are carried along with air bubbles to the surface and are thus separated from the gangue.

A molybdenum concentrate enriched in this way contains 47-50% molybdenum itself, 28-32% sulfur, 1-9% SiO2, in addition, there are impurities of other elements: iron, copper, calcium and others. The concentrate is subjected to oxidative roasting at a temperature of 560-600 °C in multi-hearth furnaces or fluidized bed furnaces. If rhenium is present in the concentrate, volatile oxide Re2O7 is formed during firing, which is removed along with furnace gases. The product of firing is the so-called “cinder” - contaminated with MoO3 impurities.

Pure MoO3, necessary for the production of molybdenum metal, is obtained from cinder in two ways. The first is sublimation at a temperature of about 1000 ° C, the second method is chemical, in which the cinder is leached with ammonia water. In this case, molybdenum goes into solution (ammonium molybdate). The solution is purified from impurities of copper, iron and other elements, then ammonium polymolybdates are isolated by neutralization or evaporation and subsequent crystallization - mainly paramolybdate (NH4)6Mo7O244H2O. After which, by calcining ammonium paramolybdate at 450-500 °C, pure MoO3 is obtained, containing no more than 0.05% impurities.

It happens that instead of firing, molybdenum concentrate is decomposed with nitric acid, and the resulting molybdic acid MoO3∙H2O is precipitated, which is dissolved in ammonia water and ammonium paramolybdate is obtained. A certain proportion of the forty-second element remains in the primary solution, from which molybdenum is extracted by ion exchange or extraction. When processing low-grade concentrates that contain 10-20% molybdenum, the cinders are leached with Na2CO3, and CaMoO4, used in ferrous metallurgy, is precipitated from the resulting Na2MoO4 solutions. Another method, using ion exchange or liquid extraction, is to transfer the Na2MoO4 solution into a (NH4)2MoO4 solution, from which ammonium paramolybdate is then isolated.

By reducing pure MoO3 in a stream of dry hydrogen, metallic molybdenum (in powder form) is obtained. The process is carried out in tube furnaces in two stages: the first at a temperature of 550-700 °C, the second at 900-1,000 °C.

Compact molybdenum is produced mainly by powder metallurgy or smelting. The powder metallurgy method involves pressing the powder into a workpiece and sintering the workpiece. Molybdenum powder is pressed in steel molds under a pressure of 0.2-0.3 MPa (2000-3000 kgf/cm2), then sintered first at 1,000-1,200 °C in a hydrogen atmosphere - preliminary sintering, the purpose of which is to increase strength and electrical conductivity of the bars, and then at 2,200-2,400 °C - high-temperature sintering. As a result, relatively small workpieces are obtained (cross-section 2-9 cm2 and length 450-600 mm). The resulting blanks (sintered bars) are processed by pressure (forging, broaching, rolling). To obtain larger billets, arc melting is used, which makes it possible to obtain ingots weighing up to two tons. Melting in arc furnaces is carried out in a vacuum. An arc is ignited between the cathode (a package of sintered molybdenum rods) and the anode (a cooled copper crucible). The cathode metal is melted and collected in a crucible. Due to the high thermal conductivity of copper and the rapid removal of heat, molybdenum hardens.

To obtain especially pure molybdenum, melting in an electron beam (electron beam melting) is used. Heating of a metal by an electron beam is based on the conversion of most of the kinetic energy of electrons into heat when they collide with the metal surface. Melting is carried out in a high vacuum, which ensures the removal of impurities that evaporate at the melting temperature (O, N, P, As, Fe, Cu, Ni and others). After such melting, the purity of the metal exceeds 99.9%.

A promising method for the production of molybdenum is the aluminothermic reduction of MoO3; the ingots obtained by this method are refined by vacuum smelting in arc furnaces. In addition, molybdenum is obtained by the reduction of MoF6 or MoCl5 with hydrogen, as well as electrolytically in molten salts. To produce ferromolybdenum (an alloy of 55-70% Mo, the rest Fe), which serves to introduce additives of the forty-second element into steel, the reduction of calcined molybdenite concentrate (cinder) with ferrosilicon in the presence of iron ore and steel filings is used.

Physical properties

Molybdenum is a light gray metal. However, its appearance largely depends on the method of production. Compacted (sintered) molybdenum without processing (in the form of bars and blanks for rolling molybdenum) is a rather dark metal, traces of oxidation are allowed. Compact rolled metal (in the form of ingots, wire or sheets) after processing comes in a variety of colors: from dark, almost black, to silvery-faded (mirror-like). The color depends on the processing method: turning, grinding, chemical cleaning (etching) and electropolishing. Molybdenum obtained in the form of a mirror (by decomposition) is shiny, but gray. The powdery forty-second element is dark gray in color.

Molybdenum crystallizes in a cubic body-centered lattice with a period of a = 0.314 nm, z = 2. Atomic radius 1.4 A, ionic radii Mo4+ 0.68 A, Mo6+ 0.62 A. The forty-second element is a refractory metal with a melting point 2620°C and boiling point - 4639°C. Only tungsten (about 3400° C), rhenium (about 3190° C) and tantalum (3000° C) have higher melting points. The density of molybdenum is 10.2 g/cm3, which is comparable to the density of silver (10.5 g/cm3), the Mohs scale defines its hardness as 5.5 points. The specific heat capacity of molybdenum at 20-100 °C is 0.272 KJ/(kg K), that is, 0.065 cal/(g deg). The thermal conductivity at 20 °C for the forty-second element is 146.65 W/(m K), that is, 0.35 cal/(cm sec deg). Thermal coefficient of linear expansion (5.8-6.2) 10-6 at 25-700 °C. Having studied the physical properties of the forty-second element, scientists discovered that the metal has a negligible coefficient of thermal expansion (approximately 30% of the expansion coefficient of copper). When heated from 25 to 500 °C, the dimensions of the molybdenum part will increase by only 0.0000055 of the original value. Even when heated above 1,200 °C, molybdenum hardly expands. This property played a big role in electrovacuum technology.

Molybdenum is paramagnetic, its atomic magnetic susceptibility is approximately 90 10-6 (at 20 ° C). Specific electrical resistance is 5.2 10-8 Ohm m, that is, 5.2 10-6 Ohm cm; electron work function 4.37 eV. The transition temperature to the superconducting state is 0.916 K. Molybdenum is a good conductor of electricity; in this parameter it is only three times inferior to silver. However, its electrical conductivity is higher than that of iron, nickel, platinum and many other metals.

Molybdenum is a malleable and ductile metal and is a transition element. Like a number of other metals, mechanical properties are determined by the purity of the metal and previous mechanical and heat treatment (the purer the metal, the softer it is). The presence of impurities increases the hardness and brittleness of the metal. Thus, when contaminated with nitrogen, carbon or sulfur, molybdenum, like chromium, becomes brittle, hard, brittle, which significantly complicates its processing. In a completely pure state, compact molybdenum is ductile, malleable and malleable, and can be stamped and rolled quite easily. The strength characteristics of molybdenum at high temperatures (but not in an oxidizing environment) exceed the strength of most other metals. For a sintered molybdenum rod, the Brinell hardness is 1500-1600 Mn/m2, that is, 150-160 kgf/mm2. For forged rod - 2000-2300 Mn/m2; for annealed wire - 1400-1850 Mn/m2. In terms of strength, molybdenum is somewhat inferior to tungsten, but it is more ductile and easier to process both mechanically and by pressure. In addition, recrystallizing annealing does not lead to metal brittleness. The metal, like its alloys, is characterized by a high elastic modulus (285-300 GPa), a small thermal neutron capture cross section (which makes it possible to use it as a structural material in nuclear reactors), good heat resistance and a low temperature coefficient of expansion.

Despite the many advantages of the forty-second element associated with its physical and mechanical properties, it also has a number of disadvantages. These include low potassium content of molybdenum; high fragility of its connections; low ductility at low temperatures. In addition, the presence of impurities of carbon, nitrogen or sulfur makes the metal hard, brittle and brittle, which greatly complicates its processing.

Chemical properties

In air at room temperature, molybdenum is resistant to oxidation. A sluggish reaction with oxygen begins at 400 ° C (so-called tarnish colors appear); at 600 ° C the metal begins to actively oxidize with the formation of MoO3 trioxide (white crystals with a greenish tint, melting point 795 ° C, boiling point 1,155 ° C), which possibly also obtained by oxidation of molybdenum disulfide MoS2 and thermolysis of ammonium paramolybdate (NH4)6Mo7O24 4H2O.

At temperatures above 700 °C, the forty-second element intensively interacts with water vapor, forming MoO2 dioxide (dark brown). In addition to the two oxides listed above, molybdenum also forms a number of oxides intermediate between MoO3 and MoO2, which correspond in composition to the homologous series MonO3n-1 (Mo9O26, Mo8O23, Mo4O11), however, all of them are thermally unstable and decompose above 700 °C to form MoO3 and MoO2. MoO3 oxide forms simple (normal) molybdenum acids - dihydrate H2MoO4 H2O, monohydrate H2MoO4 and isopolyacids - H6Mo7O24, HMo6O24, H4Mo8O26 and others.

Molybdenum does not react chemically with hydrogen until it melts. However, when the metal is heated in hydrogen, some absorption of gas occurs (at 1000 ° C, 0.5 cm3 of hydrogen is absorbed in one hundred grams of molybdenum) with the formation of a solid solution. With nitrogen, molybdenum forms a nitride above 1,500 °C, the probable composition of which is Mo2N. Solid carbon and hydrocarbons, as well as carbon monoxide CO (II) at 1,100-1,200 °C react with the metal to form carbide Mo2C, which melts with decomposition at approximately 2,400 °C.

Molybdenum reacts with silicon, forming disilicide MoSi2 (dark gray crystals do not dissolve in water, hydrochloric acid, H2SO4, decompose in a mixture of HNO3 with hydrofluoric acid), which is highly stable in air up to 1500-1600 °C (its microhardness is 14,100 Mn /m2). When the forty-second element interacts with selenium or H2Se vapor, molybdenum diselenide with the composition MoSe2 (a dark gray substance with a layered structure) is obtained; it decomposes in a vacuum at a temperature of 900 °C, is insoluble in water, and is oxidized by HNO3. When exposed to sulfur and hydrogen sulfide vapors above 440 and 800 °C, respectively, graphite-like disulfide MoS2 is formed (virtually insoluble in water, hydrochloric acid, diluted H2SO4). MoS2 decomposes above 1200 °C to form Mo2S3.

In addition to it, molybdenum forms three more compounds with sulfur, which are obtained only artificially: MoS3, Mo2S5 and Mo2S3. Mo2S3 sesquisulfide (gray needle-shaped crystals) is formed by rapid heating of the disulfide to 1700...1800° C. Molybdenum penta- (Mo2S5) and trisulfide (MoS3) are amorphous substances of dark brown color. In addition to MoS2, only MoS3 is practically used. With halogens, the forty-second element forms a number of compounds in different oxidation states. Fluorine acts on molybdenum at ordinary temperatures, chlorine at 250° C, forming MoF6 and MoCl6, respectively. Only molybdenum diiodide MoI2 is known with iodine. Molybdenum forms oxyhalides: MoOF4, MoOCl4, MoO2F2, MoO2Cl2, MoO2Br2, MoOBr3 and others.

In sulfuric and hydrochloric acids, molybdenum is slightly soluble only at 80-100 ° C. Nitric acid, aqua regia and hydrogen peroxide slowly dissolve the metal in the cold, quickly when heated. A mixture of nitric and sulfuric acids dissolves molybdenum well. The metal dissolves in hydrogen peroxide to form peroxo acids H2MoO6 and H2MoO11. Molybdenum is stable in hydrofluoric acid, but it quickly dissolves in a mixture with nitric acid. In cold alkali solutions, molybdenum is stable, but is somewhat corroded by hot solutions. The metal is intensively oxidized by molten alkalis, especially in the presence of oxidizing agents, forming salts of molybdic acid.

Molybdenum is important for the processes occurring in the human body: this metal is part of many enzymes, without which normal metabolism is impossible. Let's figure out what it affects and why it is so important for our health.

Molybdenum is a catalyst for oxidation reactions. To make it more clear what he does, let's give a simple analogy. Let's imagine that our cell is an internal combustion engine; nutrients and oxygen enter it, which, in general, is similar to gasoline and atmospheric air for an internal combustion engine. But you all probably know that if you just spray gasoline in the air, nothing will happen: you need a spark from the spark plug for the mixture to detonate and give its energy to the engine. So in the cells of our body: oxidative enzymes, such as sulfite oxidase, perform a role similar to ignition in a car engine. They trigger the process of converting nutrients and oxygen into energy necessary to maintain the functioning of our cells and tissues. As you understand, a car without ignition in the engine will not go anywhere, and a person with non-functioning oxidative enzymes will not be healthy.

And although the participation of molybdenum in redox reactions is very important for the body, this is not its only role that it plays in the human body. Molybdenum is necessary for the normal functioning of xanthate oxidase– an enzyme that ensures the processing of nitrogenous compounds in our body. Our body regularly renews its cellular composition, as a result of which there remains a lot of waste and toxins containing excess nitrogen, which is excreted with the help of urea through the kidneys. It is the enzyme xanth oxidase that allows us to transform all this organic waste that accumulates in our body into a form convenient for excretion. To use an analogy, this enzyme can be compared to putting trash into a trash bag, allowing you to throw everything away at once rather than taking empty cans and wrappers into the trash bin one at a time.

Molybdenum enters the body with food and is absorbed quite easily, depending on the form of intake it is absorbed from 25 to 80% substance supplied with food. Absorption occurs mainly in the stomach and in the initial parts of the small intestine. The supply of molybdenum from the digestive tract is also greatly influenced by the amount of sulfur compounds contained in food; their deficiency significantly complicates the absorption of molybdenum. When molybdenum enters the bloodstream, it is transported through special transport proteins to the liver, where it is used for the synthesis of enzymes. Molybdenum is excreted primarily by the kidneys; as a result, in the human body the concentration of molybdenum is highest in the liver, where it is used for the needs of the body, and in the kidneys, through which its excess is excreted. In the blood, molybdenum is evenly distributed between the cellular and liquid parts of the blood. The human body does not accumulate excess molybdenum and removes it through the kidneys and bile.

Daily requirement

A person needs per day 75-250 mcg molybdenum, depending on physical activity and body weight.

For people over 70 years of age, the need for molybdenum is reduced by approximately 25% and does not exceed 200 mcg.

According to some experts, the need for molybdenum may be slightly higher and reach 300-400 mcg.

With a normal diet, our body gets from 50 to 100 mcg molybdenum, that is, the usual diet provides the minimum required intake of this microelement.

The largest amounts of molybdenum are found in dairy products, dried beans, cabbage, spinach, gooseberries, black currants, liver, kidneys, and baked goods. There is relatively little molybdenum in carrots, fruits, sugar, oils, fats, and fish.

Overdose

Molybdenum is relatively non-toxic. For its negative effects to manifest, it is necessary to receive a dose equal to 5000 mcg, the lethal dose is 50,000 mcg. It is quite difficult to create an overdose of molybdenum: if you inhale pure metal or eat powder, then it will practically not be absorbed. In case of an overdose of biological compounds containing molybdenum, their absorption also practically stops. Molybdenum consumption is well controlled by our body, and the more it is taken in, the less it is absorbed. To reach a toxic dose, you need to eat hundreds of times more molybdenum than the dangerous dose. Acute poisoning with molybdenum practically does not occur; chronic overdose of molybdenum is in many ways similar to the conditions that arise from copper deficiency. In such a person, growth slows down, anemia develops, nitrogenous waste begins to accumulate in the blood, and gout may develop.

Shortage

Molybdenum deficiency is a fairly rare condition, but it is quite possible in some cases. Typically, such conditions develop in people receiving intravenous nutrition for a long time, for example, in people in intensive care or in patients with gastrointestinal problems.

Other causes of molybdenum deficiency may be a strict vegetarian diet that is not balanced in microelements, and genetic defects that interfere with normal absorption from the intestines. With molybdenum deficiency, the exchange of nitrogenous bases and adequate binding and excretion of inorganic sulfate compounds suffer.

With chronic molybdenum deficiency, children develop severe congenital pathologies. Normal brain development is disrupted, mental retardation develops, and vision suffers. It has also been proven that Molybdenum deficiency significantly increases the risk of developing esophageal cancer.

Summing up

We can say that molybdenum is a significant microelement for our body and its deficiency leads to serious consequences. However, there is no need to seriously fear a molybdenum deficiency under normal conditions. Our food contains it in sufficient quantities to meet daily needs. Problems with its deficiency can arise with relatively exotic diets and in severe conditions in which a person will be forced to switch to intravenous nutrition.

Lead and vanadium poisoning can also lead to molybdenum deficiency.

There is no need to be afraid of an excess of molybdenum: it develops extremely rarely, as a rule, only in workers of metallurgical production.

By including dairy products, grains, baked goods, and bovine liver and kidneys in your diet, you can easily ensure you have the right level of molybdenum for your body to function optimally.

This fairly common microelement does not require special level control, and additional intake of drugs containing it is not necessary for a relatively healthy person who does not have heavy metal poisoning.