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Learn about rhenium

Learn about rhenium

  • Categories:铼材世界
  • Time of issue:2021-03-05 17:09:22
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Rhenium is a truly rare element in rare metals

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Scattered means that the content of rhenium in the earth's crust is scarce and dispersed. Refractory means that the melting point of rhenium metal is extremely high, its melting point is as high as 3180℃, second only to tungsten. All metals are due to their compound's catalytic activity, high temperature resistance and corrosion resistance. It is mainly used in petroleum smelting catalysts, thermoelectric superalloys, electronic tube structural materials, special alloys for aerospace and aerospace, and environmental protection.

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Rhenium, as a member of the manganese sub-family, predicted its existence as early as when Mendeleev established the periodic system of elements. He called it dwi-manganese (sub-manganese), and referred to the other in this family. A member that was not discovered at the time was called eka-manganese (like manganese). Later Mosley determined that the atomic numbers of these two elements were 75 and 43, respectively. Since an unknown element can often be found in minerals with similar elements, scientists have been working to find these two elements from manganese ore, platinum ore, and columbite (minerals of tantalum and niobium). Until 1925, when German W. Nordak, I. Nordak-Tucker and OC Berg used spectroscopic analysis of niobium manganese ore, they discovered the element rhenium, named rhenium, which is derived from the Latin Rhenus, meaning It's the Rhine. Later, Nodak discovered that rhenium mainly exists in molybdenite, and extracted metal rhenium from it. Rhenium has been studied for a long time because of its lack of resources and high price. After 1950, rhenium began to be used in modern technology, and production was developing day by day. China began to extract rhenium from molybdenum concentrate roasting fumes in the 1960s and realized industrialized production. So far, it has become the country with the fastest growth in rhenium production and application.
 
The content of rhenium in the earth's crust is 0.001×10-4%, which is one of the non-ferrous metals with few reserves on the earth. The world's proven reserves are about 2500t, and the resources are 10,000t. Most of them are distributed in Chile, the former Soviet Union, Canada and other regions. The current reserves of rhenium in my country are 237t. The output of rhenium is relatively small. In recent years, the global annual output of rhenium is only 30-50t, and the consumption of rhenium is increasing steadily with the rapid development of high-tech material technology.

 

Rhenium performance

Physical properties of rhenium

Rhenium is a very hard silver-white metal that looks like platinum, but pure rhenium in powder form is generally gray in color. The physical properties of rhenium are very similar to those of the high melting point metals molybdenum and tungsten in group VII of the periodic table, and are also somewhat similar to platinum group metals, especially platinum, ruthenium, and osmium. Rhenium is a high melting point metal. Rhenium has a melting point of 3180°C, second only to tungsten. Like molybdenum and tungsten, it is a good refractory metal. Rhenium has a large specific gravity, with a relative density of 21.03g/cm3. Only platinum, iridium, and osmium have a higher specific gravity than rhenium. This feature makes rhenium the densest metal other than platinum group metals, and has very high hardness, wear resistance, Corrosion resistance and other properties. Rhenium has extremely high mechanical strength. A rhenium alloy wire thinner than a hair can withstand a gravity of more than 7 kilograms. In addition, rhenium has high resistance and other electrical properties. The resistivity of rhenium is 3.84 times that of tungsten, and its elastic modulus and mechanical properties are similar to iron. Natural rhenium is composed of two isotopes Re187 and Re185. Re187 is a radioactive isotope, accounting for 62.6% of natural rhenium; Re185 is a non-radioactive isotope, accounting for 37.2%. Re187 has a half-life of 43 million a, and the radiation emitted is very weak and cannot be penetrated. It penetrates the skin and is not harmful to the human body.

Chemical properties of rhenium

Rhenium has stable chemical properties and strong corrosion resistance. It is not oxidized in the air. Acid and alkali have little corrosive effect on it. Rhenium is stable at room temperature and starts to be oxidized at 300°C. At high temperature, it is vaporized with sulfur to synthesize rhenium disulfide, which forms halides with fluorine, chlorine, and bromine. Rhenium is insoluble in hydrochloric acid, but soluble in nitric acid and hot concentrated sulfuric acid to form perrhenic acid (HReO4). Rhenium has a strong oxygen affinity , Its oxidation states are +1, +2, +3, +4, +5, +6, +7, and the oxides are Re2O, Re2O3, ReO2, ReO3, Re2O7. The high-valent oxide of rhenium (Re2O7) is easily soluble in water and is usually processed into stable salts such as ammonium rhenate (NH4ReO4) and potassium rhenate (KReO4). Rhenium does not react with carbon and is the only element in refractory metals that does not form carbides with carbon. The most prominent chemical property of rhenium is that its heptaoxide is highly volatile, and it is easily dissolved in water and oxygenated solvents. Rhenium makes extensive use of these two properties in recycling. The aqueous solution of rhenium is acidic, and its electromotive force is between copper and thallium.Therefore, iron and zinc can make rhenium precipitate in the aqueous solution.

 

Uses of rhenium

Because rhenium has all the above-mentioned excellent properties, it has become an important material used in many fields. In the metallurgical industry, rhenium, as an alloy additive element, can improve the performance of the alloy. For example, pure tungsten and pure molybdenum become brittle like glass at low temperatures, and are difficult to process, so their use is limited. However, tungsten-rhenium alloy or molybdenum-rhenium alloy made by adding appropriate amount of rhenium to tungsten or molybdenum has good plasticity, can be processed into various structural materials, and also maintains the characteristics of high hardness, high strength and high temperature resistance. Many parts of the American manned spacecraft are made of this kind of rhenium alloy. Adding a small amount of rhenium to the chromium-nickel alloy can greatly increase the melting point and strength of the alloy. The service life of parts made of this alloy can be extended by several to tens of times.
 
Rhenium is mainly used as a catalyst in the petroleum industry, as well as element additives in superalloys and superalloys. Pure rhenium products can be used for high-temperature parts under particularly harsh working atmospheres. Metal rhenium plating (such as rhenium plating on the surface of tungsten used in space technology) can increase wear and corrosion resistance. Rhenium wire or rhenium-plated tungsten wire is used as the filament and cathode of the electron tube, and it is more durable than tungsten wire in argon or nitrogen containing trace moisture. Rhenium has high temperature stability and strong electrical corrosion resistance under the action of electric arc, so rhenium-tungsten alloy can be used in the working part of electrical contact points, and its performance can be compared with platinum and ruthenium products.
 
Rhenium has high electron emission performance and is widely used in radio, television and vacuum technology. Rhenium has a very high melting point and is a major high-temperature instrument material. Tungsten-rhenium thermocouples do not soften at 3100°C. Adding rhenium to tungsten or molybdenum to form alloys can increase ductility. Rhenium and rhenium alloys can also be used as electronic tube components and ultra-high temperature heaters to evaporate metal. Rhenium is used as a high-temperature coating on rockets and missiles. Instruments and high-temperature components used in spacecraft, such as heat shields, arc discharges, and electrical contactors, all require rhenium.

Rhenium effect-rhenium alloy

The addition of rhenium can greatly increase the strength and plasticity of tungsten, molybdenum, and chromium. People call this phenomenon the "rhenium effect". Adding a small amount (3%~5%) of rhenium can increase the recrystallization starting temperature of tungsten by 300℃~500℃. Tungsten-rhenium and molybdenum-rhenium alloys have good high-temperature strength and plasticity, and can be processed into plates, sheets, wires, wires, rods, and are used for high-temperature structural parts (spouts, nozzles, heat shields, etc.), elastic elements, and Electronic components, etc., can also be used to manufacture heating elements, workpieces, bulbs, X-ray equipment and medical equipment. W-Re-ThO2 alloy can be used as a high-temperature heating workpiece. Tungsten-rhenium and molybdenum-rhenium alloy contacts have high thermal corrosion resistance and high-temperature conductivity, which can improve the service life and working reliability of power supply equipment. Such as: platinum rhenium alloy; platinum tungsten rhenium alloy; tungsten rhenium alloy; molybdenum rhenium alloy and so on.
 
Rhenium is expensive, and alloys containing rhenium are mostly used in applications. Among them, tungsten rhenium and molybdenum rhenium alloys are the most widely used. The tungsten rhenium alloy contains 1% to 26% rhenium, and the molybdenum rhenium alloy contains 11% to 50% rhenium. In addition, there are W-33.3Mo-33.3Re, Mo-Re-Hf-Zr, Mo-Re-Hf-V alloys, tungsten base and nickel base plus rhenium diversified super heat-resistant alloys, etc. The latter alloys have high Its strength and high temperature performance are used in key components of aerospace equipment.

catalyst

In the electronic structure of rhenium, the 5 electrons in the unsaturated 4d layer are easy to release, while the 2 electrons in the 6s layer are easy to participate in the interaction to form covalent bonds. In addition to its characteristics such as large lattice parameters, rhenium and its The compound has excellent catalytic activity, and its use as a catalyst in the petrochemical industry is one of its main traditional uses. For example, it is used as a Pt-Re/Al2O3 catalyst for petroleum reforming, but with the emergence of other inexpensive substitutes such as platinum-tin catalysts, although its performance is slightly worse, the application of rhenium in this field is still reduced. In addition, rhenium can be used as a catalyst for the production of unleaded gasoline and automobiles exhaust purification; rhenium sulfide is used as a hydrogenation catalyst for cresol and lignin; NH4ReO4/C is used as a catalyst for the dehydrogenation of cyclohexane and ethanol; KReO4 ,/SiO2 is also a series of hydrogenation catalysts; Re2O7 is a good catalyst for converting SO2 to SO3 and HNO2 to HNO3.

Defense, aerospace industry

Rhenium is one of the most refractory metals, and its melting point is as high as 3180°C, which is second only to 3410°C of tungsten. A series of alloys with high temperature resistance, corrosion resistance and wear resistance can be made from rhenium and other metals. For example, Re25—W was used as a material for nuclear reactors in the space station, and later developed into a better performance Re30—W—Mo30 alloy; for Re—Pt As the structural material of atomic energy reactor, it can resist the corrosion of 1000℃ high temperature downloading hot body, and also can use radiation shield; Re-Mo alloy still has high mechanical strength up to 3000℃, and can be used to manufacture supersonic aircraft and missile high-temperature high-strength parts And as a heat shield. In particular, the successful development of nickel-based rhenium-containing superalloys used in jet engine turbine blades and thermal generator turbine materials (with rhenium 3%-7%, melting point up to 3180℃ or higher) and used in fighter jets, passenger aircraft, and firepower Generators have greatly increased the amount of rhenium in the United States and Western Europe, and also caused a sharp increase in the amount of rhenium in the world. In recent years, the use of rhenium in alloys has exceeded its use in catalysts, and super heat-resistant alloys have become its most important application field.

Temperature measurement, heating components and high temperature measurement

Thermocouples made of Re3-W and Re25-W alloy wires have a good linear relationship between temperature and thermoelectromotive force, accurate temperature measurement, and wide measurement range (0-2485°C). Its thermoelectromotive force reaches 1012mV, which is much higher than Pt-Rh/Pt (only 30mV at 1900℃). It can measure temperature to 2700℃ in vacuum or inert gas medium, and the price is cheaper than Pt-Rh/Pt thermocouple . Re28-W/W thermocouple can measure temperature to 2760℃, Mo-Re thermocouple can measure temperature to 3000℃.
 
The heating element made of rhenium-based alloy has a life span of 5-10 times longer than that of tungsten or molybdenum; the working life of Re8-12—Ni—Cr is 9 times longer than that of a Ni—Cr alloy heating element at high temperature, and has the advantages of high temperature and The outstanding advantage of normal working under pressure; Rh-Ir with added rhenium has increased strength and improved mechanical performance compared with Rh-Ir, and is used in aerospace and missiles. Rhenium-based alloys can also be used to produce springs that are both sensitive and non-deformable at high temperatures, which are necessary for high-temperature measuring instruments. As a photosensitive dye that absorbs solar energy, rhenium has broad application prospects in solar cells.

electronics industry

Alloys or coating materials composed of rhenium and tungsten, molybdenum or platinum group metals are widely used in the electronics industry due to their high melting point, high electrical resistance, strong magnetism and good stability to the environment. The tungsten wire doped with 3%-20% Re or the tungsten wire coated with H4ReO4 is not as brittle as tungsten wire, but also can improve its elongation and resistance. It has high shock and vibration resistance, so it is used in vacuum technology and Electronic devices or filaments in places prone to vibration have shown their important uses, such as X-ray targets, flash lamps, acoustic spectrometers, parts for high-vacuum voltage measurement, tungsten rhenium filaments for aircraft bulbs, and heaters for quick start of color TVs. Re-Pt, Re-Ag, Re-Cu, Re-Cu-Zr, etc. have replaced platinum as electrical contacts or shielding components such as switches, keys, current interrupters, and arc discharges, which have the advantages of reliability and durability. The molybdenum rhenium cermet anode has been put into practical use. In recent years, a rhenium-based composite material has been used as a basic material for ultra-high temperature emitters, and its thermionic discharge effect has been increased by 20%, the current density has increased, and the thermal discharge performance has been improved.

Coating and welding materials

Use rhenium's high melting point and excellent anti-corrosion and wear-resistance properties as coatings. For example, rhenium-coated metal wires, sheets or tubes can achieve the purpose of preventing acid, alkali, seawater or sulfur compounds from being attacked, so it is used Maritime and chemical sector; Re-NiRe-Mo or R-W is used as coating for instrument components, rocket warheads and their engines.
 
Adding Re to W or Mo alloy not only increases its strength, but also improves its plasticity and welding performance. It can be used as a welding rod for welding W or Mo devices.

Other uses

Medical radioactive rhenium-phosphoramidate compounds can treat cancer, and KReO4 can be used as a sensitizer for the preparation of color photographic films.

 

Overview of Rhenium Resources

There are few rhenium minerals, only rhenium (ReS2) and copper rhenium sulfide (CuReS4). Rhenium is mainly associated with minerals of molybdenum, copper, lead, zinc, platinum, and niobium. The economically valuable rhenium-containing mineral is molybdenite, which generally contains 0.001% to 0.031% rhenium. But the molybdenum concentrate selected from the porphyry copper ore contains up to 0.16% rhenium. The main raw material for the production of rhenium is a by-product of the molybdenum smelting process. Rhenium can be recovered from some copper mines, platinum group mines, niobium mines and even sphalerite smelting fume and slag, as well as waste liquid from low-grade molybdenum mines.
 
The content of rhenium in the earth's crust is 0.001×10-4%, which is one of the non-ferrous metals with few reserves on the earth. The world's proven reserves are about 2500t, and the resources are 10,000t. Most of them are distributed in Chile, the former Soviet Union, Canada and other regions. The current reserves of rhenium in my country are 237t. The output of rhenium is relatively small. In recent years, the global annual output of rhenium is only 30-50t, and the consumption of rhenium is increasing steadily with the rapid development of high-tech material technology.

 

Rhenium market

The market demand for rhenium is closely related to the development of high-tech industries. As a strategic material, the main consumer countries of rhenium are the United States, Western Europe, Japan and other developed countries and the military power Russia. In recent years, the total annual consumption of the world has reached 40t, and it has been increasing year by year. Among them, due to the better economic situation in Europe, consumption has increased rapidly, and its annual consumption has increased from 2-3t to nearly 10t. The annual consumption of rhenium in the United States remains at 20-25t. The consumption of rhenium in Japan has also increased with the recovery of the economy to a scale of about 2-3t/a, which is mainly used for electronic materials such as Re-W wires of automobiles exhaust sensors and thin-film electrodes of integrated circuits. Russia’s annual rhenium demand is about
 
Chile is the world’s largest supplier of rhenium, and it occupies more than 60% of the US’s imported rhenium raw material market; other rhenium-producing countries include the United States, Russia, Germany, and Kazakhstan
 
In recent years, due to the rapid improvement of comprehensive resource utilization technology, the amount of rhenium recovered from spent catalysts has increased steadily, and the production of primary rhenium has also increased year by year. Therefore, although the world's rhenium consumption is increasing year by year, the price of rhenium is still relatively stable.

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