Natural mineral formations thatcontain tungsten in various compounds and industrial concentrations, when mining is technically possible and economically feasible - tungsten, molybdenum in ores, as well as beryllium, tin, copper, bismuth, occasionally mercury, antimony, silver, gold, arsenic, tantalum, sulfur, scandium , niobium - the planet with such rare-earth metals, judging by the name of their group, is not rich. The by-product component of tungsten ore - molybdenum, like most others, is extracted during enrichment and converted into selective or bulk concentrates.
Swedish chemist Karl Scheele, by educationpharmacist, conducted experiments in his own laboratory. There he discovered for mankind manganese, barium, chlorine, even oxygen. Throughout his life, he did nothing but make discoveries, for which he was accepted into the Stockholm Academy of Sciences. And even shortly before his death in 1781, he didn’t stop doing what he loved to do, thus making us another great gift.
Carrying out the experience, Karl Scheele found thattungsthen (a mineral that was later named Scheelite after him) is the salt of some other unknown acid. It was a great discovery, but only two years later, chemists from Spain and his students isolated a completely new element from this mineral, which turned all the tenets in industry. However, this coup took place not immediately, a century passed before it became clear what exceptional properties tungsten has.
Depending on the deposit, all tungstenores are divided into two types: exogenous and endogenous. Among the latter are skarn, pegmatite, vein-vein (hydrothermal), greiser types of genetic ores, which are combined into three main ore formations. This is tungsten - tin, tungsten - molybdenum, tungsten - polymetals.
Sometimes tungsten is found in pegmatites, from whereand he, and scheelite extract simultaneously, leading the extraction of beryl, cassiterite, tantalum, niobates or spodumene. Pegmatite deposits - sources of alluvial placer formation - are developed most of all in South-East Asia and in Africa.
Tungsten, molybdenum in ores very closelyassociated with granite intrusions, their apical parts, where there are locking deposits, quite often accompanied by stockhole ore both intra- and supra-intrusive.
They are in the form of a mantledeposits, isometric and oval, with most often flat beds. Also, ore bodies of the column-shaped form and stockworks of irregular shape are also noted. Reserves of deposits where molybdenum, tungsten and other rare-earth minerals are present, almost never have large reserves. Ore is estimated at only tens, very rarely hundreds of thousands of tons.
Molybdenum, tungsten and other hydrothermal oresthey are located in the zones of exo- and endocontacts of granite massifs, which form rather extended in depth - up to a kilometer - whole series of steeply falling veins, the average falling of veins is much less often. Stockworks are also found. Ore bodies form with quartz-wolframite-cassiterite, quartz-wolframite inclusions, often with molybdenum, beryl and bismuthin, interspersed with quartz-molybdenite-scheelite or quartz-scheelite ores.
Обычно в таких рудах содержатся вольфрам, Molybdenum, another metal from rare earth in small quantities: tungsten is from half a percent to one and a half percent, more often - less. And this is with ore reserves of several thousand or several tens of thousands of tons, which is also very, very small. Mining is usually done by underground or open pit.
Tungsten deposits suggest waysproduction or the collapse of the layers or the horizontal maganisation of the ore layers in the waste blocks. The method of laying out the developed space is also used, which is good when developing veins, skarn or greisen deposits.
The open method assumes the presence of curtains,skarn or greisen deposits or placers. In the quarries where the ore of tungsten and molybdenum is mined, the transport system and external dumping usually work. In these cases, mining is almost completely mechanized - at ninety-five percent. But the work does not end here. Ores require enrichment, since only a maximum of one and a half percent contain rare-earth metals - tungsten, molybdenum.
На территории бывшего СССР самые значительные tungsten ore deposits have been explored in Kazakhstan, Eastern Siberia and the Far East, the Caucasus and Central Asia. Not all of them are developed. Abroad, the processing of tungsten and molybdenum is especially abundant in South Korea and China. There are the most significant deposits in the world. In addition, tungsten is mined in Portugal, Australia, Canada, Bolivia, USA, France, Austria and Turkey.
Here it must be said that Southeast Asiaand its Pacific ore belt has more than sixty percent of all tungsten reserves on earth. All in all, in the explored deposits of the planet total reserves of tungsten are much less than one and a half million tons. For example, gold is mined annually (not in reserves, but it is being used) about 4,278,200 tons.
Being one of the most refractory metals,Tungsten becomes literally indispensable in all areas that are associated with high temperatures. As a chemical element, Wolframium (W) is in the fourth group of the periodic system. Its atomic mass is 183.85, and the number is 74. It received the name due to its light gray color - from German Wolf and Rahm are translated as "wolf" and "cream", if literally - "wolf foam". Despite its refractoriness, it is stable at ordinary temperature. Minerals supplying tungsten are schehelite and wolfram.
Tungsten - one of the most important componentssuperhard heat-resistant steels - high-speed and tool, as well as alloys having the same properties - stellite, win and so on. But we see pure tungsten every day, since it is widely used in electrical engineering. For example, in incandescent lamps, tungsten filaments. It is also indispensable in electronics. Electronic devices have cathodes and anodes of this metal.
Processing tungsten and molybdenum is difficult, butextremely beneficial. The industry knows several brands, among which there are more common and less. Tungsten is pure, with additives and in alloys with other metals. Thus, the VR brands are distinguished - an alloy of tungsten and rhenium; VL - with lanthanum oxide as an additive; VI - with yttrium oxide; BT - thorium oxide as an additive; VM - with silica alkali and thorium additive; VA - with silicon-alkali and aluminum additives; HF - pure tungsten.
Tungsten serves as the basis for hard alloys, andthe alloy of tungsten and molybdenum is heat resistant, like some others. Also, with his participation, wear-resistant tool steel is being prepared. Such alloys make many parts of engines - aviation and space, in electric vacuum devices - various parts and filaments. Since the density of this metal is very high, it is used for counterweights, for bullets and artillery shells, for ballistic missiles (flight stabilization, tungsten withstands all one hundred eighty thousand revolutions per minute) for ultra-high-speed rotors, metals such as tungsten and molybdenum are also used. Their use, as we see, is very wide and even, one might say, exquisite.
Without these rare earth metals what arechrome, molybdenum, tungsten, today, neither medicine nor nuclear physics. Single crystals of all tungstates serve as scintillation detectors of x-rays, as well as other ionizing radiation. Tungsten Ditelluride (WTe2) used in the conversion of thermal energy into electrical energy. Even argon arc welding uses tungsten as an electrode.
Tungsten compounds are especially widely used.Composite materials and hard alloys based on tungsten carbide are needed for the machining of both metals and non-metallic structures. This is especially necessary in mechanical engineering: milling, turning, chiselling, planing. Hard alloys can not be dispensed with while drilling wells and in the mining industry, and for this, tungsten and molybdenum are needed - production masters new technologies with their help.
Sun2 (tungsten sulfide) - high-temperature grease,withstanding up to five hundred degrees Celsius. Where solid electrolyte is produced (high temperature fuel cells), tungsten trioxide is used. Textile, paint and varnish industries significantly improved and complicated technologies using tungsten compounds as a catalyst and pigment in organic synthesis.
Industry produces a huge amounta variety of products containing tungsten, molybdenum and other rare earth metals. The most common are electrodes, wire, tungsten powder, sheet and bead. The electrodes never melt and therefore can be used for welding high alloy steels, non-ferrous metals and materials with different chemical compositions. Not a single electrode will provide such a high strength weld.
Molybdenum alloys and it belongs to materialsrefractory. In its pure form, it is used in the form of a wire or tape for heating appliances - electric furnaces, even operating in hydrogen with a temperature of 1600 ° C. Molybdenum sheet and wire are needed in the electronic industry, they are also used in X-ray technology, and various parts for x-ray tubes, electron tubes, and vacuum devices are made from molybdenum.
In addition, molybdenum, like tungsten, is verywidely used to improve steels. Molybdenum additive increases strength, hardenability, corrosion resistance, viscosity. Therefore, tungsten and molybdenum are used to create the most critical products and the most important parts. For hardness, stellites - chrome and cobalt are introduced into such an alloy to fuse the edges of wear parts. Chrome, molybdenum, tungsten - such an alloy is almost impossible to erase. He was also given one of the first places in the series of acid-resistant and heat-resistant alloys.
Alloy of tungsten and molybdenum in the composition of the skinthe head of any rocket and aircraft. In terms of strength, tungsten comes first, and molybdenum comes second. However, the specific strength at temperatures of about one and a half thousand degrees Celsius brings molybdenum alloys to the first place. If the temperatures are even higher, then tungsten and tantalum are invincible. Molybdenum is used to make honeycomb panels for all aircraft, capsule shells and rockets that return to Earth, heat exchangers, heat shields, wing-edge sheathing, and stabilizers.
Where difficult working conditions helprare earth metals. From such a material, one can expect high resistance to oxidation and gas erosion, high strength and ability to hold impact. Many details of turbojet and rocket engines, tail skirts, turbine blades, nozzle flaps, control surfaces, rocket engine nozzles and so on - molybdenum copes with all these difficult jobs.
Promising materials for equipment thatwork in the environment of phosphoric, sulfuric and hydrochloric acids, are made of molybdenum and its alloys. It is resistant even in molten glass, and therefore the glass industry widely uses molybdenum as electrodes for melting.
From its alloys rods and molds are madefor high pressure casting of copper, zinc and aluminum alloys. Steel is processed with molybdenum under pressure - stamps, dies, mandrels of piercing mills. Molybdenum steel itself also significantly improves.
