Chemistry is the foundation of our lives. All household items consist of compounds of elements of the periodic table. Every minute in the human body, complex transformations occur, in which chemicals participate. This article will talk about a metal such as molybdenum: where applicable, its properties and role in the human body.
Delve into history
Minerals containing molybdenum were known in ancient Greece. These natural compounds had a structure similar to graphite. Therefore, they were often used along with it to create leads. MoS₂ molybdenite had a gray-green hue when writing on paper. For its characteristic brilliance, he was given the name molybdaena - “lead-like”.
Karl Wilhelm Scheele carried out studies due to which he synthesized MoO₃ trioxide, but due to the lack of a suitable furnace he could not isolate the metal in its pure form. Jöns Jacob Berzelius managed to obtain molybdenum in 1817 by reducing oxide not with coal, but with hydrogen. The synthesized chemical element was thoroughly investigated and described in the works of a scientist.
Physical properties
What is molybdenum? This is a light gray metal, which in its pure form is resistant to oxidation (under normal conditions). With increasing temperature to 400-600 degrees, this ability decreases, and MoO₃ trioxide is formed.
Molybdenum is ductile and forging, easy to stamp. The density of the metal is 10.2 g / cm 3 , the melting point is 2620 ° C, and the boiling point is 4800 ° C. From these indicators it can be seen that it is quite refractory. The presence of carbon, nitrogen or sulfur contaminants affects the physical properties, in particular, the substance becomes brittle and brittle. Molybdenum is a paramagnet. With increasing temperature, its strength increases significantly.
Natural Molybdenum Compounds Getting
You should know that in its pure form molybdenum does not occur, it is present in nature exclusively in compounds with other elements. The approximate metal content in the earth's crust is 3 ∙ 10 -4 %. There are about 15 minerals, of which the most common are:
- MoS 2 disulfide - molybdenite;
- CaMoO 4 - command;
- PbMoO 4 - Wulfenite.
The main deposits of these compounds are closely related to the deposition processes in hydrothermal sources.
For industrial purposes, the molybdenum element disulfide is mined. Its use to obtain pure metal is very important. This happens with the help of ore dressing by flotation. Thus, a concentrate is obtained, which is subsequently calcined.
2MoS 2 + 7O 2 = 2MoO 3 + 4SO 2
The isolated oxide is purified and reduced with a dry stream of hydrogen at a temperature of 700 degrees. The reaction product is molybdenum powder. In the future, it can be used in pure form or as a material for the creation of rolled and stamped products.
Alloy Steel Production
Ferrous metallurgy uses molybdenum powder. Where is it used? For alloying steels and cast irons. Adding this element to the composition of the alloys significantly improves their quality. Increases elasticity, wear resistance, resistance to shock. About 0.5% of molybdenum is added to structural steels, from which their structure becomes fine-grained and more uniform, the fragility of the final products is reduced.
Adding other substances allows you to get special compositions that are widely used in various industries. Alloys containing cobalt and nickel (50-60%), as well as chromium (about 20-28%) are alloyed by adding molybdenum. Where is such material used? The answer lies in its special properties - high heat resistance. It is used in the manufacture of skin parts for aircraft and missiles.
The use of alloys with molybdenum
When niobium, titanium and other heavy-duty metals are added to molybdenum, the heat resistance of alloys increases. Such a composition can be used to create parts for gas turbines and combustion chambers in rocket science.
In alloys containing a large amount of molybdenum (17–28%), corrosion resistance increases. They are not afraid even of interaction with any acid (except hydrofluoric).
The refractory properties of molybdenum and its use in the creation of special pipes are of great importance in nuclear energy. Such products can withstand molten lithium. It acts as a coolant in uranium reactors. In addition, molybdenum itself in the form of the Mo-99 isotope has found application as an indicator in the nuclear industry.
Due to the refractoriness of molybdenum, molds are created from it for casting parts from copper, aluminum and zinc. The high strength of the metal allows processes to be carried out under high pressure.
Hire and stamping, application
Of the blanks obtained by powder smelting, rolling products are created - rods and wire. They are made of pure metal called molybdenum. Where are such products used? Most often it is used in the manufacture of thermocouples, which are used to measure temperatures above 2000 ⁰C. Hooks and cores for winding tungsten filament in an incandescent lamp are also made of molybdenum wire. Inputs of cathodes and focusing electrodes in X-ray tubes and generator lamps must be reliable and meet the requirements of high refractory metal. Molybdenum rental is excellent for these purposes.
Rods and plates are used instead of electrodes in high-temperature melting furnaces. They must be in a special environment consisting of argon, hydrogen or vacuum. Due to the fact that molybdenum does not enter into chemical reactions with glass, it is used for the manufacture of parts of a melting furnace.
Application in other industries
Molybdenum has found application in the oil industry. There it is used as a catalyst capable of purifying products from sulfur impurities. Lubricants are made from aluminum disulfide. They stabilize the operation of various devices and protect surfaces from mechanical stress at high temperatures. This lubricant also has anti-corrosion properties.
In the manufacture of paints and varnishes, where molybdenum and its oxides are used, stable pigments of yellow-orange tones are obtained. Synthesis of artificial fibers also does not pass without this substance. To increase the nitrogen content in the soil, microfertilizers are used, which include molybdenum.
The role of molybdenum in the body
Molybdenum has a significant role in the human body. He is involved in the synthesis of hemoglobin, nitrogen and purine metabolism. Responsible for the absorption of iron and vitamin C, is a powerful antioxidant. The trace element has an oncoprotective, anti-aging effect.
Foods rich in molybdenum include legumes and cereals, leafy vegetables. The necessary amount of a microelement daily enters the body if you eat right. Its shortage can be made up using mineral complexes.