What Are the Uses of Molybdenum?

Molybdenum ^[1] (mù) is an essential trace element for the human body, animals and plants. It is silver-white metal, hard and tough. Various tissues of the human body contain molybdenum, the total amount of which is 9mg in the human body, the highest content in liver and kidney.

The biological properties of molybdenum are also important. It is an essential trace element not only for plants but also for animals. Molybdenum is one of the main components of the molybdenum protease in nitrogen-fixing bacteria in plants; it is also one of the main components of nitrate reductase in plants; it can also stimulate phosphatase activity and promote the synthesis and transportation of sugar and starch in crops; it is beneficial to early maturity . Molybdenum is one of the seven important micronutrients. Molybdenum is also one of the basic components of xanthine oxidase and aldehyde oxidase in the liver and intestines of animals, and it is also the basic component of heparin oxidase. Studies have shown that molybdenum also has a significant anti-caries effect, molybdenum has a strong inhibitory effect on the formation of urinary stones, and humans are vulnerable to kidney stones due to lack of molybdenum. A healthy person weighing 70 kg contains 9 mg of molybdenum in the body. For humans, molybdenum is the only element known to be essential to humans among the second and third types of transition elements. Compared with similar transition elements, molybdenum is extremely toxic and can even be considered to be essentially non-toxic. Of course, excessive ingestion will also accelerate the oxidation of the elastic substance-plasmalogen-in the arterial wall of the human body. Therefore, in areas where the soil contains too much molybdenum, the incidence of cancer is lower but the incidence of gout and systemic arteriosclerosis is higher. Animals that eat too much molybdenum-containing forage, especially long-horned animals, are susceptible to stomach problems.

Metabolic absorption

Molybdenum compounds in diet and drinking water are easily absorbed. Soluble for oral intake

In terms of the distribution of molybdenum ore in China, Central and South China accounted for 35.7% of the country's molybdenum reserves, ranking first. This was followed by 19.5% in Northeast China, 14.9% in Northwest China, 13.9% in East China, and 12% in North China, and only 4% in Southwest China. In terms of provinces (regions), Henan has the largest reserves, accounting for 29.9% of the country s total molybdenum reserves, followed by Shaanxi with 13.6% and Jilin with 13%. In addition, provinces (regions) with large reserves are: Shandong accounts for 6.7%, Hebei accounts for 6.6%, Jiangxi accounts for 4%, Liaoning accounts for 3.7%, and Inner Mongolia accounts for 3.6%. The total reserves of the above 8 provinces (regions) accounted for 81.1% of the total reserves of molybdenum ore in the country, of which the top three provinces of Henan, Shaanxi and Jilin accounted for 56.5%. The following table shows the main molybdenum deposits in China and their development and utilization. ^[5]

Molybdenum is a refractory rare metal like tungsten. Since the discovery of molybdenum by Swedish scientist CWSCHEELE in 1778, it took more than ten years of hard work in M.MOISSAN to obtain metal molybdenum in an electric furnace, making it possible for the first time to obtain this metal with many excellent physical, chemical and mechanical properties. The melting point of molybdenum is 2620 ° C. Due to the strong bonding between atoms, the strength is very high at room temperature and high temperature. It has a small expansion coefficient, large electrical conductivity, and good thermal conductivity. It does not react with hydrochloric acid, hydrofluoric acid and alkaline solutions at normal temperature, but is only soluble in nitric acid, aqua regia or concentrated sulfuric acid. It is also quite stable to most liquid metal, non-metal slag and molten glass. Therefore, molybdenum and its alloys have a wide range of applications and good prospects in important sectors such as metallurgy, agriculture, electricity, chemical industry, environmental protection and aerospace, and have become an important raw material and irreplaceable strategic substance in the national economy. Molybdenum reserves on the earth are relatively small, its content only accounts for 0.001% of the weight of the crust, and the total reserves of molybdenum ore are about 15 million tons, mainly distributed in the United States, China, Chile, Russia, Canada and other countries. China's proven molybdenum metal reserves are 1.72 million tons and its basic reserves are 3.34 million tons, ranking second only to the United States in the world. Molybdenum deposits are concentrated in four provinces including Shaanxi, Henan, Jilin and Liaoning. There are six super-large molybdenum ore deposits in the world with metal reserves of more than 500,000 tons. China's Henan Luanchuan, Jilin Daheishan, and Shaanxi Jinduicheng list three major molybdenum mines. Abundant molybdenum resources have provided extremely favorable conditions and a solid foundation for the development of smelting and processing of molybdenum in China and vigorously promoting the application of molybdenum. In recent years, China's molybdenum mining, smelting and processing have developed rapidly. According to the data, in 2001 China actually produced 72,000 tons of molybdenum concentrate, 33,000 tons of molybdenum oxide, 7600 tons of iron molybdenum, 9500 tons of various types of ammonium molybdate, 1183 tons of molybdenum bars, 1200 tons of molybdenum slabs, 150 tons of molybdenum plates, and molybdenum. More than 40 tons of wafers, about 50 tons of molybdenum heads and other special-shaped products, 3.15 billion meters of molybdenum wire in the electric light source industry and machining, and hundreds of tons of chemical products such as lubricants, catalysts, pigments. Not only that, China occupies an important position in the world molybdenum market. According to customs statistics, in 2001 China exported as much as 70,274 tons of molybdenum ore roasting, molybdate, ferromolybdenum and other molybdenum products, earning US $ 262 million in foreign exchange earnings. The consumption form of molybdenum is mainly industrial molybdenum trioxide, which accounts for about 70%, iron molybdenum accounts for about 20%, and metal molybdenum and molybdenum chemicals each account for 5%. Its application fields and distribution ratios are as follows: iron and steel smelting consumption accounts for about 80% (of which alloy steel is about 43%, stainless steel is about 23%, tool steel and high speed steel are about 8%, cast iron and rolls are about 6%), chemical industry Products account for about 10%, metal molybdenum products account for about 6%, high-temperature high-strength alloys and special alloys account for about 3%, and other molybdenum products account for about 1%. It can be seen from the above that the development of the steel industry plays a decisive role in the consumption of molybdenum, but with the development of science and technology, the application of molybdenum in high-tech and other fields will continue to expand and develop.

Iron and steel industry According to the molybdenum consumption statistics of countries around the world, the application of molybdenum in the steel industry still occupies the most important position. As an alloying element of steel, molybdenum can improve the strength of steel, especially high temperature strength and toughness; improve the corrosion resistance of steel in acid and alkali solutions and liquid metals; improve the wear resistance of steel and improve hardenability and weldability And heat resistance. Molybdenum is a good carbide-forming element. It does not oxidize during steelmaking. It can be used alone or in combination with other alloying elements. The molybdenum consumption of special steel is increasing regularly. At present, the molybdenum consumption per ton of special steel has reached the level of 0.201 kg.

Molybdenum and chromium, nickel, manganese and silicon can make different types of stainless steel, tool steel, high speed steel and alloy steel. The produced stainless steel has good corrosion resistance and can be used for corrosion-resistant steel pipes for oil extraction. A stainless steel with about 6% molybdenum can also replace titanium for seawater desalination equipment,

Ocean-going vessels, offshore oil and gas extraction pipelines. This type of stainless steel can also be used in car shells, sewage treatment equipment, and so on. Molybdenum-containing tool steel is twice as efficient as tungsten tools, with excellent performance, low cost, and light weight. Molybdenum series high-speed steel has the advantages of carbide non-uniformity, wear resistance, good toughness, high temperature plasticity, etc., and is suitable for manufacturing forming tools. Molybdenum alloy steel can be used to make machine tool structural parts, industrial vehicles and bulldozers. Molybdenum alloy steel with fine pearlite structure in the rolled state is an important steel in the construction of rails and bridges.

As an alloy additive of iron, molybdenum helps to form a completely pearlite matrix, which can improve the strength and toughness of cast iron, improve the uniformity of the structure of large castings, and improve the hardenability of heat-treated castings. Molybdenum gray cast iron has good wear resistance and can be used as brake wheels and brake pads of heavy vehicles.

The agricultural fertilizer molybdenum is one of the necessary "trace elements" in the plant, which accounts for about 0.5 ppm of the dry matter of the plant, which is indispensable and irreplaceable. In recent years, ammonium molybdate has been widely used as a trace element fertilizer at home and abroad, which can significantly improve the quality and yield of legumes, forages and other crops. This is mainly because molybdenum can promote the fixation of nitrogen in the air by rhizobium and other nitrogen-fixing organisms, and further transform nitrogen into protein required by plants. Molybdenum can also promote the absorption of phosphorus by plants and exert its effect in plants. Molybdenum can also accelerate the formation and transformation of sugars in plants, increase the content and stability of chlorophyll in plants, and increase the content of vitamin C. Not only that, molybdenum can improve the plant's drought and cold resistance and disease resistance.

The application of molybdenum fertilizer is characterized by small amount, large effect and low cost. It is an important measure to increase agricultural yields, especially soybean yield. The widespread application of molybdenum in agriculture has also opened a new way for the comprehensive utilization of wastewater, waste residue and low-grade ore in molybdenum production plants in China. Electronic and electrical molybdenum has good electrical conductivity and high temperature performance, especially its thermal expansion coefficient is very similar to glass. It is widely used in the manufacture of the core wire, lead wire, hook, bracket, side bar and other components of spiral filaments in light bulbs. Make grid and anode support materials. Molybdenum is used as a metal oxide semiconductor gate in very large integrated circuits. Installing the integrated circuit on molybdenum can eliminate the "bimetal effect". Ultra-thin seamless molybdenum tube (about 15m) can be used as the anode support of high-definition television picture tubes. The image scanning line of this television reaches 1125, which is twice as high as that of ordinary televisions. Molybdenum wafers can also be used as substrates and heat sinks for power transistor heat shields and silicon rectifiers.

In addition to using pure molybdenum in the modern electronics industry, Mo-Re alloys can be used as structural materials for electronic tubes and special light bulbs, and Mo-50Re and TZM alloys can also be used as thermionic cathode structural elements in high-power microwave tubes and millimeter-wave tubes. Its operating temperature can reach 1200 ° C and its current density can reach 10 amps / cm2. The pure molybdenum wire used as a lead wire has a low recrystallization temperature and is prone to embrittlement at high temperatures, which affects the service life. In recent years, some people have developed the addition of Si, k, and C to increase the recrystallization temperature and produce "high temperature Molybdenum wire". Adding rare earth elements yttrium, cerium and lanthanum in the production process of molybdenum oxide can effectively increase the recrystallization temperature and overcome the problem of high temperature embrittlement of the material. Molybdenum wires containing 0.1-0.3% zirconium and 0.1% hafnium are nitrided at 1200 ° C to disperse hafnium throughout the alloy. The tensile strength of this molybdenum wire at 20 ° C can reach 1,400 million pascals.

The rapid development of the mold industry has made EDM technology widely used. Molybdenum wire is the ideal wire for EDM machine tools. It can cut all kinds of steel and hard alloys. It has extremely complex shapes. Its electrical discharge machining. Stable, can effectively improve the accuracy of the mold. The above are the two most widely used molybdenum wires, the development of light bulb manufacturing and the rise of mold manufacturing.

Leap forward. According to statistics from the China Lighting Association, the national production of molybdenum wire reached 3.15 billion meters in 2001. The actual output is estimated to reach 4 billion meters and consume nearly 800 tons of molybdenum bars, which is a considerable amount. Among them, the output of molybdenum wire for wire cutting exceeds 2 billion meters, accounting for more than half of the total molybdenum wire, and its market development prospects are very optimistic.

Molybdenum use

Molybdenum is mainly used in the iron and steel industry, most of which are directly used in steelmaking or cast iron after industrial molybdenum oxide briquettes, and a small part is smelted into ferromolybdenum

Molybdenum foil

It is then used in steelmaking. The content of molybdenum in low alloy steel is not more than 1%, but the consumption in this area accounts for about 50% of the total consumption of molybdenum. Adding molybdenum to stainless steel can improve the corrosion resistance of steel. Adding molybdenum to cast iron can improve the strength and wear resistance of iron. A nickel-based superalloy containing 18% molybdenum has the characteristics of high melting point, low density, and small thermal expansion coefficient, and is used to manufacture various high temperature resistant parts for aviation and aerospace. Metal molybdenum is widely used in electronic devices such as tubes, transistors and rectifiers. Molybdenum oxide and molybdate are excellent catalysts in the chemical and petroleum industries. Molybdenum disulfide is an important lubricant used in the aerospace and machinery industries. In addition, molybdenum disulfide, because of its unique anti-sulfur properties, can catalyze the hydrogenation of carbon monoxide to produce alcohols under certain conditions. It is a promising C1 chemical catalyst. Molybdenum is one of the trace elements necessary for plants and is used as a trace element fertilizer in agriculture.

Molybdenum has the potential to replace graphene in the electronics industry ^[8] .

The California Institute of Nanotechnology (CNSI) successfully used MoS2 (molybdenum, molybdenum disulfide) to successfully produce a molybdenum-based flexible micro-processing chip. This MoS2-based microchip is only 20% of the size of an equivalent silicon-based chip. The power consumption is extremely low. The power consumption of a molybdenum-based transistor in standby is one hundred thousandth that of a silicon transistor, and it is cheaper than a graphene circuit of the same size. The biggest change is that the circuit is very flexible, extremely thin, and can be attached to human skin.

In 2011, scientists from the Swiss Federal Institute of Technology in Lausanne (EPFL) created the world's first molybdenite microchip (with smaller and more energy-efficient transistors on it). Molybdenum is a strong competitor to replace silicon-based chips in the future. Professor Andras Kish, who led the research, said that molybdenum is a good next-generation semiconductor material and has broad prospects for manufacturing ultra-small transistors, light-emitting diodes and solar cells.

Compared with silicon and graphene, one of the advantages of molybdenum molybdenum is its smaller size. Molybdenum monomolecular layer is two-dimensional, while silicon is a three-dimensional material. On a 0.65 nanometer thick molybdenum thin film, electron movement is as easy as on a two nanometer thick silicon thin film. Molybdenite can be processed to only 3 atoms thick!

The mechanical properties of molybdenum molybdenum have also attracted attention, and it has the potential to become a material used in flexible electronic devices such as flexible thin-layer wafers. It can be used to make a computer that can be curled or a device that can be attached to the skin. It can even be implanted in the human body.

The British "Nature · Nanotechnology" magazine pointed out that the single layer of molybdenum material shows good semiconductor characteristics. Some properties exceed the widely used silicon and research graphene, which is expected to become the next-generation semiconductor material.

Pure molybdenum wire is used for high temperature electric furnace and EDM processing and wire cutting processing; molybdenum sheet is used to make radio equipment and X-ray equipment; molybdenum is high temperature resistant

Molybdenum crucible

Ablation is mainly used in the manufacture of artillery bores, rocket nozzles, and tungsten wire supports for electric bulbs. Adding molybdenum to alloy steel can improve the elastic limit, corrosion resistance and maintain permanent magnetism. Molybdenum is one of the seven micronutrients required for plant growth and development. Without it, plants cannot survive. Animals and fish, like plants, also need molybdenum.

The application of molybdenum in other alloy fields and chemical fields is also expanding. For example, molybdenum disulfide lubricants are widely used in the lubrication of various types of machinery, and molybdenum metal is gradually used in nuclear power, new energy and other fields. Because of the importance of molybdenum, governments in various countries regard it as a strategic metal. Molybdenum was widely used in the manufacture of weapons and equipment in the early twentieth century. Modern high-end, precision, and pointed equipment have higher requirements for materials, such as molybdenum and tungsten, chromium, Vanadium alloys are used to make alloy components and parts for warships, rockets, and satellites.

Molybdenum is also widely used as a substrate for different film surfaces in thin-film solar and other coating industries.

Molybdenum

Ammonium Molybdate

Role and application: Molybdenum is a component of many enzymes. Deficiency of molybdenum can cause diseases such as dental caries, kidney stones, Keshan disease, Kashin-Beck disease, and esophageal cancer. It is mainly used for patients who are dependent on intravenous high nutrition for a long time.

The main function of molybdenum in the body is to participate in the mutual reaction between sulfur, iron and copper. Molybdenum is an essential factor for xanthine oxidase, aldehyde oxidase and sulfite oxidase to exert their biological vitality, and it has certain effects on the electron transfer, metabolism of purine substances and sulfur-containing amino acids in the body's redox process. Of these three enzymes, molybdenum is present as a co-factor derived from purine. Molybdenum can also inhibit the absorption of iron and copper by the small intestine. The mechanism may be that molybdenum can competitively inhibit the receptors on the brush border of the small intestinal mucosa, or form copper-molybdenum complexes, sulfur-molybdenum complexes, or sulfur that are not easily absorbed. Copper molybdate (Cu-MoS) prevents it from binding to copper-containing proteins such as plasma ceruloplasmin.

Dosage: Oral, the daily dosage for adults is 0.1-0.15mg.

Children need 0.03 0.1mg daily.

[Side effects]: Excessive molybdenum can cause adverse reactions.

[Precautions]: Daily intake exceeds 0.54mg, molybdenum can increase copper excretion from urine. When it exceeds 10 to 15 mg, gout syndrome may occur.

Application amount in dairy feed: 10mg / d

Molybdenum molybdenum alloy

Non-ferrous alloy formed by adding molybdenum as the base and other elements. The main alloying elements are titanium, zirconium, hafnium, tungsten and rare earth elements. Titanium, zirconium,

Molybdenum alloy

Rhenium not only plays a solid solution strengthening role for the molybdenum alloy and maintains the low-temperature ductility of the alloy, but also forms a stable, dispersedly distributed carbide phase, which improves the strength and recrystallization temperature of the alloy. Molybdenum alloy has good thermal conductivity, electrical conductivity, and low coefficient of expansion. It has high strength at high temperatures (1100 to 1650 ° C) and is easier to process than tungsten. It can be used as the grid and anode of electronic tubes, the supporting material of electric light sources, and used for making die casting and extrusion molds, parts of spacecraft, etc. The development of molybdenum alloys is limited due to their low temperature brittleness and welding brittleness, and their high temperature easily oxidizes. Industrially produced molybdenum alloys include molybdenum-titanium-zirconium-based, molybdenum-tungsten-based, and molybdenum-rare-earth-based alloys. The most widely used is the first type. The main strengthening methods of molybdenum alloy are solid solution strengthening, precipitation strengthening and work hardening. Molybdenum alloy plates, strips, foils, pipes, rods, wires and profiles can be made through plastic processing, and their strength and low-temperature plasticity can be improved.

Molybdenum is an important element in steel and alloys. The commonly used molybdenum-containing charge materials are metal molybdenum and iron molybdenum. Sometimes molybdenum oxide concentrates can be used to directly reduce and smelt molybdenum-containing steel. The natural reserves of molybdenum in the crust are 19 million tons, and the recoverable reserves are 8.6 million tons. ^[9]

Molybdenum medical imaging

Molybdenum-99 is one of the radioactive isotopes of molybdenum and is used in the hospital to prepare thorium-99. Thorium-99 is a radioactive isotope that can be used by patients for imaging of internal organs. The molybdenum-99 used for this purpose is usually absorbed in alumina powder and stored in a relatively small container. When molybdenum-99 decays, thorium-99 is formed. The thorium-99 can be removed from the container and sent to Patient ^[1] .