What is "rare earth"? Why are the people so afraid of rare earths?

Rare elements---rare earth. On the periodic table

Some metal elements are very rare

And such elements

It is also an indispensable raw material in modern electronic technology.

Rare earth is not found everywhere.

Even if it is

it must be discovered by extreme It is extracted from many minerals

so the price is very expensive. Therefore, some countries (such as the United States, etc.) do not develop it even if they have

< p> Because it is a small amount of rare earth

and a large amount of land is destroyed

so that the land can no longer be cultivated

And in the process of mining and refine

A large amount of toxic chemicals pollutes the surrounding areas

and endangers the health of the staff, making the environment worse day by day!!! These conditions are reflected one by one from China's rare earth mines

.

Rare earth Rare earth metals, or rare earth elements, are the collective name for 17 chemical elements including scandium, yttrium and lanthanide elements in Group III of the periodic table. Scandium and yttrium are considered rare earth elements because they often occur in mineral deposits with lanthanide elements and have similar chemical properties. Talking about structural chemistry does not seem to be very important. Even if I look for information, I just look at it casually and will not remember it. After all, we are not scientists, so we should be practical. Let’s talk about the functions and applications of rare earths 1. Magnetic materials: neodymium, Samarium, praseodymium, dysprosium, etc. are the main raw materials for manufacturing modern super permanent magnet materials. Their magnetic properties are 4 to 10 times higher than ordinary permanent magnet materials. They are widely used in high-tech fields such as televisions, audio, medical equipment, maglev trains, and military industry. . Experts predict that the output value of such materials will reach US$3.5 billion by the end of this century. 2. Hydrogen storage materials: MMNi5 (MM is mixed rare earth metal) and LaNi5, intermetallic compounds of rare earths and transition elements, are excellent hydrogen absorbing materials and are called “hydrogen sponges”. 3. Precision ceramics: Yttria-stabilized pickaxe oxide is a structural ceramic with excellent performance and can be used to make knives and scissors for various special purposes; it can be used to make automobile engines because of its high thermal conductivity, low expansion coefficient, and good thermal stability. The working intensity does not decrease at 1650°C, and it has the advantages of high engine horsepower and fuel saving. 4. Catalyst: In addition to being used to manufacture petroleum cracking catalysts, rare earths are widely used in many chemical reactions, such as rare earth oxides La2O3, Nd2O3 and Sm2O3. Cyclohexane is dehydrogenated to produce benzene, and LnCoO3 is used instead of platinum to catalyze the oxidation of ammonia to produce nitric acid. And it is used as a catalyst in the production of synthetic isoprene rubber and butadiene rubber. 5. Electric light source industrial field: As the luminescent material of fluorescent lamps, rare earths are energy-saving light sources characterized by good light efficiency, good light color, and long life. It can save 75-80% of electricity than incandescent lamps. 6. Luminescent materials for displays: Among rare earth elements, yttrium and europium are the main raw materials for red phosphors, which are widely used in color TVs, computers and various monitors. 7. Laser materials: Rare earth ions are the most important catalysts for solid laser materials and inorganic liquid laser materials. Among them, Nd3+-doped laser materials are the most studied, except for yttrium aluminum garnet (YAG), yttrium aluminate (YAP) glass, etc. In addition to basic quality, high rare earth concentration laser materials may be called materials for special applications. At present, many countries have widely used crystals doped with rare earth elements as lasers. 8. Metallurgical industry: Rare earths are widely used in the metallurgical industry, accounting for about 1/3 of the total use of rare earths. Rare earth elements easily react with oxygen and sulfur to form oxides, sulfides, and sulfur-oxygen compounds with high melting points and little plasticity at high temperatures. Adding rare earth elements to molten steel can desulfurize and deoxidize the steel, improving the normal and low-temperature toughness and fracture properties of the steel. properties, reduce the thermal brittleness of some steels and improve the heating workability and the firmness of welded parts. 9. Petrochemical industry: Rare earths are used as rare earth molecular sieve cracking catalysts in the petroleum cracking industry. They are characterized by high activity, good selectivity, and high gasoline productivity.

Rare earths are used in large amounts in this area. 10. Glass industry: Rare earths have three applications in the glass industry: glass coloring, glass decolorization and preparation of glass with special properties. Rare earth oxides used for glass coloring include neodymium (pink with purple luster), praseodymium glass (for manufacturing filters), etc.; cerium dioxide can oxidize the yellow-green ferrous iron in the glass into trivalent iron. Decolorization of valence iron avoids the toxicity of arsenic oxides used in the past. Neodymium oxide can also be added for decolorization; rare earth special glasses such as cerium glass (anti-radiation glass) and lanthanum glass (optical glass). 11. Ceramic industry: Rare earths can be added to ceramics and enamels to reduce glaze cracking and make them shiny. Rare earths are mainly used as pigments for porcelain. Rare earth oxides can be used to make high-temperature-resistant transparent ceramics (used in laser and other fields) and high-temperature-resistant crucibles (metallurgy). 12. Other fields: As we all know, special steel used in the manufacture of guns, bombs, aircraft, cars, tanks, warships, etc.; wires for transportation, telecommunications, and motors, etc., are mostly composite products of multiple metals; various power equipment, engines Launching requires fuel, coal and oil are indispensable; military buildings and military equipment, including some military supplies such as military clothing, require non-metallic materials; manufacturing atomic bombs and hydrogen bombs requires uranium ore and other radioactive minerals; such as yttrium aluminum garnet laser measurement The distance meter can measure a distance of 4

000 to 20

000 meters with an accuracy of ±5 meters. It is said that tanks and other weapon systems of the United States, Germany, Japan, Britain, and Israel all use this type of laser rangefinder. These functions are just a list of some big projects. When broken down, there are thousands of places that need to be used. Life is inseparable from modern science and technology, but rare earths are such an important resource. Just like oil, not every country has land production. For example, although Japan is a major manufacturing country in the world's automobile industry and rare earths are indispensable raw materials in modern automobile manufacturing technology, Japan itself does not produce rare earths. If China or some rare earth-producing countries do not If we supply rare earths, the Japanese automobile industry will be finished immediately~ There were rumors a few years ago that we would not supply rare earths to the Japanese automobile industry. At that time, Japanese automobile stock prices plummeted... It is really important to control resources. Unfortunately, Taiwan It does not produce much rare earths and must rely on imports. China controls 52% of the world's rare earth resources. However, China is over-exploited and sells its resources to other countries at a low price. Some even predict that China may have 50% of rare earths at its current consumption rate in another 50 years. Crisis of rare earth exhaustion. Although the United States itself has 12% of the world's rare earth resources, it has the same policy as oil. Although it produces a lot, it does not develop it and only buys foreign resources. ~~Keep your own country’s resources~~~If one day the earth’s resources are about to be exhausted~how popular the resources saved by the United States will be? I have already talked about the functions of rare earths and the importance of their application. I hope you will not abandon the topic and vote. ~I hope you can decide for yourself and choose the best answer. Thank you

Reference: Internet information and personal opinions

The word "earth" in "rare earth" actually refers to oxidation things. When these elements were discovered they were thought to be very rare on Earth. In fact, their content in the earth's crust is quite high, with the highest content of cerium being the 25th most abundant element in the earth's crust, higher than lead. The content of the lowest "rare earth metal" lutetium in the earth's crust is even 200 times higher than that of gold. Therefore, the International Union of Pure and Applied Chemistry has now abandoned the term "rare earth metals".