What is molybdenum?

Not many people know that molybdenum is a chemical element of the sixth group of the periodic table related to transition metals. In the classification structure, it is adjacent to chromium and tungsten. It features a rich gray color and a specific metallic sheen. This refractory element is widely used in the metallurgical industry.

A brief history of the discovery

Not much information has been preserved to this day about the discovery of molybdenum. This is because the item is not too common. However, the first mention of it was made in 1778, when analytical chemistry had not yet had time to enter the era of maturity. First, the substance was isolated as oxide.

Despite the discovery of the chemical element in 1778, the name currently used appeared much earlier. It was often mentioned for minerals with a lead sheen, back in the Middle Ages.

Environmental presence

Although molybdenum is not a very common element, it is distributed relatively evenly in the earth's crust. In free form, he does not occur. The smallest amounts of this metal include carbonate and ultrabasic rocks. A certain proportion of the substance is contained in river and sea water. In the upper layers there is much less metal than in the depths.

There are two forms of occurrence:

• sulfide;
• molybdate.

They appear in the form of microscopic secretions. Crystallization of molybdenite occurs with increased acidity and the presence of a reducing environment. Oxygen compounds are usually formed on the surface. As for primary ores, molybdenite can be found in them together with the minerals of copper, bismuthine, and tungsten. In large volumes, metal is found in sedimentary deposits.

Large deposits in Russia

In the Russian Federation, the use of molybdenum is carried out in many fields of activity. The country has one of the largest mineral resources in the world for the extraction of this metal. The main share of enterprises is concentrated in the southern part of Siberia.

In terms of reserves, Russia is second only to three states - the United States, China and Chile. The bulk of the mineral resource base is represented by stockwork deposits containing more than 87% of proven resources. However, Russian deposits are characterized by not very high quality ores.

The table shows the largest deposits.

Practical use

In its pure form, the use of molybdenum is carried out in the manufacture of wires or tapes designed to withstand high temperatures. Such products can act as heating elements for electric furnaces, electron tubes or x-ray tubes.

The presented metal significantly improves the performance of steels. After its introduction into the composition, their strength properties and corrosion resistance increase, which is necessary in the manufacture of important parts. Often with the addition of molybdenum, heat-resistant alloys are produced , which are also distinguished by acid resistance.

Compounds with this metal are actively used in the manufacture of the front skin of aircraft and missiles. Based on alloys, honeycomb panels for aircraft and thermal screens are produced. Resistance to high temperatures allows the use of products with the introduction of molybdenum for steel processing. Many compounds act as catalysts for chemical reactions.

Physical and chemical properties

Molybdenum is a light gray metal with a cubic lattice with volume centering. Its mechanical properties are determined by the purity of the material itself, as well as by preliminary and heat treatment. Physical properties are discussed in more detail in the table below.

Under normal conditions, the component of the periodic table is resistant to many substances. The oxidation process begins to occur at temperatures above 400 degrees. Alkaline solutions on molybdenum have a slow effect. Resistance to moisture without aeration is quite high.

Compounds with other metals

The quality of the obtained molybdenum alloys largely depends on the proportion, as well as the ability of the used impurities and the base component to interact with the substance. An important role is played by alloying technology. However, certain types of compounds make experts doubtful as to their suitability for further use.

Molybdenum does not mix well with tungsten. With its introduction, the heat resistance of the material significantly increases, but at the same time, the resistance to deformation deteriorates. Similar problems arise in combinations with other metals, so these types of alloying ceased to be carried out.

Despite the existing difficulties, it was still possible to find some compounds that can increase the thermal threshold for the use of molybdenum. At the same time, ductility, resistance to deformation and other characteristics are at the same level.

Brands in the industry

The production process involves the use of material not only in its pure form, but also with the addition of impurities. Below are the brands of molybdenum that are common in the industry.

Receipt process

Ore is prepared for the production of molybdenum, which includes up to 50 percent of the basic substance, a significant amount of sulfur, a small concentration of silicon and other components. It is fired at a temperature of 570 to 600 degrees in special furnaces. After thermal exposure, a concentrate is formed containing molybdenum oxide with impurities.

There are two ways to get mass without foreign substances:

1. By the method of successive effects of a chemical nature. When using ammonia water, the resulting cinder turns into a liquid state. Extraneous impurities are removed from the resulting solution. After processing, their amount should not exceed 0.05 percent.
2. By sublimation, which is the process of converting a solid compound into a gaseous state. In this embodiment, the liquid phase is bypassed.

Purified from impurities, molybdenum oxide is processed in a tube furnace by means of hydrogen. As a result, a powder is obtained, which is converted directly to metal by melting and introducing special substances. The shape of the blanks will depend on the production technology used.

Molybdenum Products

The most common type of products are bars. They can not only be used independently, but also serve as the basis for the production of wire. Molybdenum racks having a square section of not more than 40 mm are used as raw materials for the manufacture of products.

In the process of obtaining rods, rotational forging is carried out, passing in several stages. At each stage, bars with a certain section are made. Forging conditions vary with the diameter of the incoming workpiece. The disadvantages of the technology include the complexity of the production process.

Molybdenum is also used to make special wire. Manufacturers form it from properly prepared rods, the diameter of which does not exceed 3 mm. With this cross section, the products are easily wound onto a spool for further wire production.

In the manufacturing process, the broaching method is applied, which includes four main stages. The wire eventually gets the final diameter, which was set in advance. The temperature regime during the production process can range from 300 to 700 degrees.

After drawing, the wire is cleaned by annealing in a hydrogen medium. In this case, the temperature reaches 1300-1400 degrees. Sometimes cleaning is carried out by electrolytic etching using nitrogen.

Molybdenum can be used to produce whole sheets and ribbons. They can be obtained by forging and rolling. By production pneumatic hammers and two-roll mills are used. The thickness of the resulting tape after hot rolling depends on the cross section of the original plate.

After manufacturing, molybdenum strips undergo chemical cleaning. They are placed in a special environment of active substances. Next, cold rolling is carried out at ordinary temperature. At the final stage, the tapes are again cleaned and, if necessary, polished.

There are manufacturing standards for molybdenum metal products. GOST 18905-73 sets the requirements for the manufacture of wire. It reflects the permissible deviations of the mass and diameter.

Molybdenum producers in Russia

Skarn, stockwork and vein deposits are mainly developed in the Russian Federation. The quality of ore mined is not much inferior to foreign raw materials, but it still has certain features associated with the structure.

In Russia, the largest producers of molybdenum are two companies:

• LLC Sorsky GOK.
• JSC "Zhireken GOK".

The listed enterprises provide up to 95 percent of domestic metal production.

In conclusion, the role of the element for the human body

Molybdenum acts as an important substance necessary for the normal functioning of people. It is found in many organs and bone tissue. The daily need for a chemical element averages 70-300 mcg. With its deficit, these indicators increase.

Molybdenum takes part in the metabolism, as well as in the process of cleansing the body of aldehydes, acids and other compounds. It contributes to the utilization of iron, allowing you to quickly eliminate the consequences of various types of poisoning. The trace element effectively cleanses the body of toxic substances.

Studies have shown that molybdenum relieves pain in arthritis and other diseases, has a positive effect in the presence of asthma, and reduces the risk of cancer in the intestines and stomach. Most substances are found in leafy vegetables, buckwheat, barley, liver, eggs, milk, gooseberries and black currants.