What is rare earth?

The word rare earth is a name left over from history. Rare earth elements have been discovered since the end of 18. At that time, people often called solid oxides insoluble in water soil. Rare earth is usually separated in oxide state, which is relatively rare, so it is named rare earth. Lanthanum, cerium, praseodymium, neodymium, promethium, samarium and europium are commonly referred to as light rare earths or cerium groups. Gadolinium, terbium, dysprosium, holmium, erbium, thulium, ytterbium and lutetium yttrium are called heavy rare earth or yttrium rare earth. Some are divided into three groups according to the similarities and differences of physical and chemical properties of rare earth elements, except scandium (some are classified as sparse elements), that is, the light rare earth group is lanthanum. The medium rare earth group is samarium, europium, gadolinium, terbium and dysprosium; The heavy rare earth groups are holmium, erbium, thulium, ytterbium, lutetium and yttrium. Japan is a major user of rare earths, and the number of rare earths exported by China ranks first in the world. As the key material of many major weapon systems, the United States almost always needs to import from China (to some extent, it is a strategic reserve). Rare earth is the most abundant strategic resource in China, which is necessary for many high-tech industries. However, rare earth resources are very rich. At present, resources are a country's precious wealth and an important weapon for developing countries to safeguard their own rights and interests and resist the power of big countries. Comrade * *, the chief architect of China's reform and opening up, once said meaningfully, "There is oil in the Middle East and we have rare earths." Rare earth is a new type of functional material with many characteristics such as electricity, magnetism, light and biology. It is an important basic material in high-tech fields such as information technology, biotechnology, energy technology and national defense construction, and also plays an important role in transforming some traditional industries, such as agriculture, chemical industry and building materials. Rare earth is widely used, and there are many kinds of functional materials that can use rare earth, which is forming a large-scale high-tech industrial cluster. It has a very broad market prospect and extremely important strategic significance. It has the reputation of "industrial vitamin". In the military field, rare earths are known as industrial "gold". Because of its excellent physical properties such as photomagnetism, it can form new materials and various varieties with different properties with other materials. Its most significant function is to greatly improve the quality and performance of other products, such as the tactical performance of steel, aluminum alloy, magnesium alloy and titanium alloy used to manufacture tanks, airplanes and missiles. Moreover, rare earth is also a lubricant for electronics, lasers, nuclear industry, superconductivity and many other high technologies. Once rare earth technology is used in the military, it will inevitably bring about a leap in military science and technology. In a sense, the US military has overwhelmingly controlled it in several local wars after the Cold War. And being able to kill the enemy openly and unscrupulously is precisely because of its advantages in the field of rare earth science and technology. In metallurgical industry, rare earth metals or fluorides and silicides can play a role in refining, desulfurization, neutralizing harmful impurities with low melting point and improving the machinability of steel. Rare-earth ferrosilicon alloy and rare-earth ferrosilicon magnesium alloy are used as nodulizers to produce rare-earth nodular cast iron, which are widely used in machinery manufacturing industries such as automobiles, tractors and diesel engines because they are particularly suitable for producing complex nodular cast iron with special requirements. Adding rare earth metals to non-ferrous alloys such as magnesium, aluminum, copper, zinc and nickel can improve the physical and chemical properties of the alloy and improve its mechanical properties at room temperature and high temperature. In petrochemical industry, rare earth molecular sieve catalyst has the advantages of high activity, good selectivity and strong resistance to heavy metal poisoning, thus replacing aluminum silicate catalyst for petroleum catalytic cracking. In the process of synthetic ammonia production, a small amount of rare earth nitrate is used as cocatalyst, and its gas treatment capacity is 1.5 times that of nickel-aluminum catalyst; In the process of synthesizing cis-polybutadiene rubber and isoprene rubber, rare earth naphthenate-triisobutyl aluminum catalyst is used, and the obtained products have the advantages of excellent performance, less equipment adhesion, stable operation and short post-treatment process. Composite rare earth oxides can also be used as catalysts for purifying the tail gas of internal combustion engines, and cerium naphthenate can also be used as paint drier. In glass ceramics, rare earth oxides or processed rare earth concentrates can be widely used as polishing powder for polishing optical glass, spectacle lenses, picture tubes, oscilloscopes, flat glass, plastics and metal tableware. In the process of melting glass, the strong oxidation of cerium dioxide to iron can be used to reduce the iron content in glass, so as to achieve the purpose of removing green from glass; Adding rare earth oxides can make optical glass and special glass with different uses, including glass that can pass infrared rays and absorb ultraviolet rays, glass that is acid-resistant and heat-resistant, and glass that can prevent X rays. Adding rare earth to ceramic glaze and porcelain glaze can reduce the fragmentation of glaze and make products show different colors, which is widely used in ceramic industry. In terms of new materials, rare earth cobalt NdFeB permanent magnet materials have high remanence, high coercivity and high magnetic energy product, which are widely used in electronics, aerospace and other industries. Garnet ferrite single crystals and polycrystals composed of pure rare earth oxides and iron oxides can be used in microwave and electronic industries. Neodymium glass made of yttrium aluminum garnet and high purity neodymium oxide can be used as solid laser materials; Rare earth hexaboride can be used to make cathode materials for electron emission; La-Ni metal is a newly developed hydrogen storage material in 1970s. Lanthanum chromate is a high temperature thermoelectric material; In recent years, the superconducting materials made of Ba-based oxides modified by Ba, Y, Cu and O can obtain superconductors in the temperature range of liquid nitrogen, which makes a breakthrough in the research and development of superconducting materials. In addition, rare earths are also widely used in lighting sources, projection TV phosphors, intensifying screen phosphors, tricolor phosphors and copy lamp powders. In agriculture, applying a small amount of rare earth nitrate to field crops can increase the yield by 5 ~10%; In textile industry, rare earth chloride is also widely used in tanning fur, fur dyeing, wool dyeing and carpet dyeing. The results of agricultural research show that rare earth elements can increase the chlorophyll content of plants, enhance photosynthesis, promote root development and increase the absorption of nutrients by roots. Rare earth elements can also promote seed germination, improve seed germination rate and promote seedling growth. In addition to the above main functions, it also has the ability to enhance the disease resistance, cold resistance and drought resistance of some crops. A large number of studies also show that the use of appropriate concentrations of rare earth elements can promote the absorption, transformation and utilization of nutrients by plants. The germination and jointing stage of maize were 1~2 days earlier than that of the control, and the plant height was increased by 0.2 meters, 3~5 days earlier, and the seeds were full.

What is rare earth?

Rare earths are lanthanide elements in the periodic table of chemical elements-La, Ce, Pr, Nd, Pm, Sm, Eu, Gd and Tb. RaRE earth (re or r) for short. Most rare earth metals are paramagnetic. At 0℃, gadolinium is more ferromagnetic than iron. Terbium, dysprosium, holmium and erbium are also ferromagnetic at low temperature. The low melting point of lanthanum and cerium and the high vapor pressure of samarium, europium and ytterbium show great differences in physical properties of rare earth metals. Samarium, europium and yttrium have larger thermal neutron absorption cross sections than cadmium and boron, and they are widely used as control materials for nuclear reactors. Rare earth metals have plasticity, among which samarium and ytterbium are the best. Except ytterbium, the hardness of yttrium group rare earth is higher than that of cerium group rare earth. Rare earth metals have been widely used in electronics, petrochemical industry, metallurgy, machinery, energy, light industry, environmental protection, agriculture and other fields. The application of rare earth can produce fluorescent materials, rare earth metal hydride battery materials, electric light source materials, permanent magnet materials, hydrogen storage materials, catalytic materials, precision ceramic materials, laser materials, superconducting materials, magnetostrictive materials, magnetic refrigeration materials, magneto-optical storage materials, optical fiber materials and so on.

China is rich in rare earth mineral resources with superior metallogenic conditions, and its proven reserves rank first in the world, which provides a solid foundation for the development of rare earth industry in China.

The above is the standard definition of search encyclopedia. I hope it can be adopted. Thank you. Have a good mood.

What are rare earths and what are their uses?

The word rare earth [x and T incarnations] is a name left over from history.

Rare earth elements were discovered at the end of 18. At that time, people often called water-insoluble solid oxides soil. Rare earth is generally separated in oxide state, which is relatively rare, so it is named rare earth.

Lanthanum, cerium, praseodymium, neodymium, promethium, samarium and europium are usually called light rare earth or cerium group rare earth; Gadolinium, terbium, dysprosium, holmium, erbium, thulium, ytterbium and lutetium yttrium are called heavy rare earths or yttrium rare earths. According to the similarity and difference of physical and chemical properties of rare earth elements, some of them are divided into three groups (some are classified as sparse elements), that is, the light rare earth groups are lanthanum, cerium, praseodymium, neodymium and promethium; The medium rare earth group is samarium, europium, gadolinium, terbium and dysprosium; The heavy rare earth groups are holmium, erbium, thulium, ytterbium, lutetium and yttrium.

Rare earth is a new type of functional material with electrical, magnetic, optical and biological characteristics. It is an important basic material in high-tech fields such as information technology, biotechnology, energy technology and national defense construction, and also plays an important role in transforming some traditional industries, such as agriculture, chemical industry and building materials. Rare earth is widely used, and there are many kinds of functional materials that can use rare earth. A large-scale high-tech industrial cluster is being formed, which has a very broad market prospect and extremely important strategic significance.

It has the reputation of "industrial vitamin".

What is rare earth? Where is it distributed in the country?

Rare earths are lanthanide elements in the periodic table of chemical elements-La, Ce, Pr, Nd, Pm, Sm, Eu, Gd, Tb, etc.

RaRE earth (re or r) for short. See: World Rare Earth Network Rare Earth Classification XWTX1) Light rare earths (also known as cerium group): lanthanum, cerium, praseodymium, neodymium, promethium, samarium, europium and gadolinium.

2) Heavy rare earths (also known as yttrium group): terbium, dysprosium, holmium, erbium, thulium, ytterbium, lutetium, scandium and yttrium. The difference between cerium group and yttrium group is that the rare earth mixture obtained by mineral separation is often named because of the high proportion of cerium or yttrium.

Rare earth metals, also known as rare earth elements, are the general names of scandium, yttrium and lanthanide series 17 in group Ⅲ b of the periodic table of elements, and are usually represented by r or re. Their names aNd chemical symbols are scandium (sc), yttrium (y), lanthanum (la), cerium (ce), praseodymium (pr), neodymium (nd), promethium (Pm), samarium (Sm), europium (eu), gadolinium (Gd) and gadolinium.

Their atomic numbers are 2 1(Sc), 39(Y), 57(La) to 7 1(Lu) respectively. The name comes from the word rare earth, which is a name left over from history.

The discovery of these rare earth elements, from the separation of yttrium by Finn J. Gadolin in 1794 to the preparation of promethium by J. A. Malinschi in 1947, lasted for more than 50 years. Most rare earth elements were discovered by some European mineralogists, chemists and metallurgists.

Polonium was obtained by Malinschi, L.E. Grand Ning and C.D. Corell of the United States from rare earth elements in uranium fission products through ion exchange separation. In the past, it was thought that promethium did not exist in nature until 1965, when a phosphate factory in Finland treated apatite, a trace of promethium was found.

Properties and applications of rare earth elements Most rare earth metals are paramagnetic. At 0℃, gadolinium is more ferromagnetic than iron.

Terbium, dysprosium, holmium and erbium are also ferromagnetic at low temperature. The low melting point of lanthanum and cerium and the high vapor pressure of samarium, europium and ytterbium show great differences in physical properties of rare earth metals. Samarium, europium and yttrium have larger thermal neutron absorption cross sections than cadmium and boron, and they are widely used as control materials for nuclear reactors.

Rare earth metals have plasticity, among which samarium and ytterbium are the best. Except ytterbium, the hardness of yttrium group rare earth is higher than that of cerium group rare earth.

Rare earth metals have been widely used in electronics, petrochemical industry, metallurgy, machinery, energy, light industry, environmental protection, agriculture and other fields. The application of rare earth can produce fluorescent materials, rare earth metal hydride battery materials, electric light source materials, permanent magnet materials, hydrogen storage materials, catalytic materials, precision ceramic materials, laser materials, superconducting materials, magnetostrictive materials, magnetic refrigeration materials, magneto-optical storage materials, optical fiber materials and so on.

Rare earth elements mainly exist in the form of single minerals in nature. At present, there are more than 250 kinds of rare earth minerals and minerals containing rare earth elements in the world, among which there are 50-65 kinds with rare earth content of ∑REE >:5.8%, which can be regarded as independent rare earth minerals. The important rare earth minerals are mainly fluorocarbon and phosphate.

The general characteristics of rare earth minerals are: first, the lack of sulfide and sulfate (only a few), which shows that rare earth elements have oxygen affinity; Second, the silicate of rare earth is mainly island-shaped, without layered, frame-shaped and chain-shaped structure; Thirdly, some rare earth minerals (especially complex oxides and silicates) are amorphous; Fourthly, the distribution of rare earth minerals is mainly silicate and oxide in magmatic rocks and pegmatite, and fluorocarbon and phosphate are mainly in hydrothermal deposits and weathered crust deposits. Most yttrium-rich minerals occur in granite and pegmatite, aerogenic hydrothermal deposits and related hydrothermal deposits. Fifth, rare earth elements are often born in the same mineral because of their similar atomic structure, chemistry and crystal chemistry, that is, cerium rare earth elements and yttrium rare earth elements often exist in the same mineral, but these elements do not exist in the same amount. Some minerals are mainly rare earths containing cerium, while others are mainly yttrium.

At present, more than 250 kinds of rare earth minerals and minerals containing rare earth elements have been discovered, and the only industrial minerals suitable for current smelting conditions are 10: 1) cerium group minerals containing rare earth (lanthanum, cerium and neodymium): bastnaesite, bastnaesite and monazite. 2) Minerals rich in samarium and gadolinium: beryl, niobium yttrium ore and black rare gold ore.

3) Rare earth minerals containing yttrium (yttrium, dysprosium, erbium, thulium, etc.). ): xenotime, bastnaesite, yttrium dissolved stone, brown yttrium ore, black rare gold ore. In nature, dispersed elements mainly exist in related metal minerals, such as sphalerite, which is generally rich in cadmium, germanium, gallium and indium. Some also contain thallium, selenium and tellurium; Chalcopyrite, tetrahedrite and chalcopyrite are often rich in thallium, selenium and tellurium, and some are also rich in indium and germanium. Galena is also often rich in indium, thallium, selenium and tellurium; Molybdenite and bornite are rich in rhenium, and some are also rich in selenium. Pyrite is usually rich in thallium, gallium, selenium and tellurium.

At present, although nearly 200 kinds of rare element minerals have been discovered, they are not rich because they are rare.

What is rare earth? What can it do?

Rare earth is rare earth in English, which means "rare earth". In fact, this is just a misunderstanding left over from the18th century. After 1787, several rare earth elements were discovered one after another, but few corresponding minerals were found. Due to the limitation of science and technology at that time, people could only produce some oxides as impure as soil, so people left such a unique and interesting name for this group of elements.

According to the definition of rare earth elements by the International Union of Pure and Applied Chemistry, rare earth elements are lanthanides with atomic number 57-7 1 in the third subgroup of Mendeleev's periodic table. That is, lanthanum (57), cerium (58), praseodymium (59), neodymium (60), promethium (6 1), samarium (62), europium (63), gadolinium (64) and terbium (3). Except scandium and promethium, other 15 elements are Chang Shengcheng.

According to the differences of physical and chemical properties and geochemical properties between rare earth elements and the requirements of separation process, scholars often divide rare earth elements into light, heavy or light, medium and heavy groups. The division of the two groups is based on gadolinium. Seven elements before gadolinium, namely lanthanum, dysprosium, cerium, praseodymium, neodymium, promethium, samarium and europium, are light rare earth elements, also known as cerium group rare earth elements. After gadolinium and gadolinium, nine elements such as terbium, dysprosium, holmium, erbium, thulium, ytterbium, lutetium and yttrium are called heavy rare earth elements, also known as yttrium rare earth elements. Although the atomic weight of yttrium is only 89, its chemical properties are closer to those of heavy rare earth elements because its ion radius is in the ion radius chain of other heavy rare earth elements. In nature, it also appears with other heavy rare earth elements. Therefore, it is classified as a heavy rare earth group. There are no certain rules for the classification of light, medium and heavy rare earths. According to the solubility of rare earth sulfate double salt, it can be divided into: insoluble cerium group is light rare earth group, including lanthanum, cerium, praseodymium, neodymium and samarium; The insoluble terbium family is a medium rare earth family, including europium, gadolinium, terbium and dysprosium; The more soluble yttrium group is the heavy rare earth group, including yttrium, holmium, erbium, thulium, ytterbium and lutetium. However, the solubility difference of each group of adjacent elements is very small, so it is not clear by this method. At present, the extraction method is commonly used to group. For example, using bis (2) ethylhexyl (phosphoric acid), P204 can be grouped between neodymium and samarium, and then between gadolinium and terbium. Lanthanum, cerium, praseodymium and neodymium are called light rare earths, samarium, europium and gadolinium are called medium rare earths, and terbium, dysprosium, holmium, erbium, thulium, ytterbium and lutetium plus yttrium are called heavy rare earths.

The content of rare earth in the earth's crust is not uncommon. The Clark value of this group of elements is 0.0236%, including 0.0 1.592% for cerium group and 0.0077% for yttrium group. It is more than common elements such as copper (0.0 1%), zinc (0.005%), tin (0.004%), lead (0.00 16%), nickel (0.008%) and cobalt (0.003%). This group of elements is not soil, but a group of typical metal elements, whose activity is second only to alkali metals and alkaline earth metals.

Table 1- 1 Abundance of Rare Earth Elements in the Crust

Su yuan Ming Ming

scandium (Sc)

The sixth note of the major scale

cerium (Ce)

praseodymium (Pr)

neodymium (Nd)

Prime minister

samarium (Sm)

Crustal abundance, ppm

3 1

9. 1

4.5* 10- 1

7.06

Su yuan Ming Ming

europium

gadolinium

Trillion byte

dysprosium (Dy)

hum

thulium (Tm)

ytterbium (Yb)

lutecium (Lu)

Crustal abundance, ppm

2. 1

6. 1

1.2

4.5

1.3

0.5

3. 1

0.8

The position of rare earth elements in the periodic table is very special. The element 17 belongs to ⅲ b group, and scandium, yttrium and lanthanum are the first elements in the fourth, fifth, sixth and long-period transition elements series respectively. Lanthanum is very similar to the following element 14 in nature, and chemists can only put them in one lattice. No wonder some people regard them as "isotopes", but because of their different atomic numbers, they can't be counted as real isotopes. That is to say, their properties are similar, but they are not exactly the same, which brings difficulties to the separation of this group of elements, but it also shows that separation is possible as long as they make use of their subtle differences; On the other hand, their electronic structure has an internal electronic layer that is not completely filled, that is, a 4f electronic layer. Because of the different number of electrons in the 4f layer, each element in this group has a very special personality, especially optical and magnetic properties, just like a piano with a complete keyboard and a wide range.

Information, biology, new materials, new energy, space and ocean are pushed into six new science and technology groups by contemporary scientists. People attach importance to, research and develop rare earths because rare earth elements have their own fields in these six science and technology groups. However, after all, rare earth elements are still a group of elements that have not been fully understood by people, and we need to make great efforts to study and understand them, so as to support them and make them make greater contributions to mankind.

What are the main rare earth elements in China? My question is about the owners of rare earth mines in China.

Of the 48 million tons of rare earth resources in the world, China ranks first in the world, followed by the United States, India, the Soviet Union, Malawi, South Africa, Australia and Canada, accounting for 5.2 million tons, 2.5 million tons, 500,000 tons, 330,000 tons, 320,000 tons, 200,000 tons and 6.5438 tons respectively. By 1987, the total output converted into REO reached 1.5 1 10,000 tons, ranking first in the world. Rare earth minerals in China can be roughly divided into three types: fluorocarbon borane, monazite and ion adsorption minerals. Fluorocarbon decorative copper mine is mainly produced in Baiyunshan iron mine in Inner Mongolia Autonomous Region. Processing and producing crude rare earth chloride, various separated rare earths and rare earth alloys. Monazite is mainly produced in Guangdong and Hunan provinces, and contains medium and heavy rare earth elements such as wool. It is also processed and produced into crude rare earth chloride and various separated rare earths. Ion-adsorbed minerals are mainly produced in Jiangxi province, and have been developed on a large scale since the 1980s, and made into high-purity oxidation memories and various intermediate rare earth products.