Rare Earth

1. What is rare earth?

Rare earth is a group of elements of peculiar nature, comprising the 17 elements under subgroup III B of Mendeleyev's periodic table. They are a group of typical metal elements rather than earth.

Rare earth elements and their chemical compounds are characterized by their high fusing point, great density and high thermal and electricity conductivity, and are able to generate a wide variety of electron energy levels. They can be widely used in various fields due to their many special physical and chemical natures such as magnetism, luminosity, superconductivity and environmental non-toxicity, etc.

Rare earth elements are widely used in six major high and new technology industries, including information, biology, new materials, new energy, space and ocean. Such elements are indispensable functional materials for the high and new technology and sophisticated technology worldwide. It can be asserted that the development of high and new technology industry would not be possible without rare earth.

Different industries range from traditional industries such as metallurgy, nonferrous metal smelting, petroleum and chemical engineering, glass, ceramics and home appliances, etc. to nowadays high-tech electronic devices, computers, electric motors, automotive air purifiers, permanent-magnet materials, nano materials, magnetic memory chips, fibre optics, superconductors and precision optics, etc. all require rare earth.

2. How about the application of the respective rare earth elements?

The application of rare earth is still at its developmental stage, with new research results coming out every year. Currently, the principal applications of the respective rare earth elements are as follows:

Name of element
La The manufacture of various alloys, such as alumni alloy for aircraft; illuminating materials, such as highway sign board and luminous stone mounted on road surface; optical glass, such as camera and camcorder lens; optical fibre; high-class condenser; glass decolourizer for strength enhancement; laser materials; colour and polishing materials for porcelain, magnetic resistance materials; hydrogen-storage materials; mobile phone battery; catalyst for organic chemical products, such as photoconvert agricultural film.
Ce The production of fluorescent powder; radiation and ultraviolet ray protection optical glass, such as autoglass; additive for special intensified glass; petrol cracking catalyst; electronic devices for computer, oven, microwave oven and air-conditioner; automotive air purifying catalyst; plastic colouring used in dyestuff, printing ink and paper; solid laser.
Pr Mainly used in glass, ceramic and magnetic materials; the production of high-class porcelain colour; petrol cracking catalyst; polishing abradant; optical fibre; alloy for watch winding; the manufacture of permanent magnet for used in various electronic devices and motors.
Nd ¤NdFeB permanent magnetic materials; automatic lock for automobile engine, doors and windows; superconductivity material used in the electronics industry; mobile phone battery; computer hard driver; nonferrous metal materials widely used in the aerospace industry; shortwave laser beam widely used for welding and cutting thin materials; medical laser used in surgical removal or wound sterilization; glass and porcelain colouring and rubber product additives.
Sm High-class permanent magnetic materials used in the national defence industry; reactor control materials used in the nuclear industry; Sm cobalt series permanent magnet; ceramic condenser; catalyst; structural materials for atomic reactor; screen materials.
Eu Fluorescent powder, fluorescent screen for colour TV and computer display, and trichomatic fluorescent lamp; control stick used in the nuclear industry; new X ray radioactivity medical diagnosis system; the manufacture of colour lens and optical filter; magnetic bubble storage device; control materials, screen materials and structural materials for atomic reactor.
Gd GGG crystal line materials; laser instrument; nuclear and magnetic resonance imaging device; special luminance oscillograph tube and X ray intensifying screen; magnetic bubble memory; solid state magnetic refrigerant; super conductive magnet; inhibitor for controlling nuclear power station; Sm cobalt magnet addictive; for improving glass stability; condenser.
Tb Fluorescence green powder activator; high-class magnetic materials; magnet-optical storage materials, magnet-optical disc, computer storage element, computer memory chip; magnet-optical glass laser rotator, separator and circulator; magnetostrictance alloy; sonar; fuel-injection system; liquid valve control; micropositioning mechanical brake; space telescope regulating device and airfoil regulator.
Dy Measured neutron energy spectrum for the nuclear industry; metal halogen light materials; photomagnetic record alloy; super permanent magnetic materials; NdFeB series permanent magnet addictive; laser; fluorescent powder activator; magnetostrictance alloy; photomagnetic storage materials; Dy lamp used as luminous source for films and printing; for testing neutron energy spectrum or neutron absorber in the nuclear industry; magnetic refrigerant.
Ho Thermonuclear reaction activator; medical operation laser device; Ho crystal, laser crystal; metal halogen light addictive; magnetostrictance alloy addictive; optical communication devices such as optical fibre, optical fibre laser device, optical fibre amplifier, optical fibre sensing transmitter, etc.¯ ¡C
Er Luminous materials; super conducting materials; photo conductive fibre; Er optical fibre amplifier optical device; laser crystal; infrared glass for snooperscope, portable military laser telemeter; rare-earth glass solid laser materials; spectacles glass; crystal glass decolouring and colouring.
Tm X ray; super conducting materials; portable X ray generator for medical use; portable blood irradiator; clinical diagnosis and tumour treatment; fluorescent powder activator for X ray intensifying screen; new luminous metal halogen light addictive; rare-earth glass laser materials.
Yb Manufacture of superalloy products; hot screen-coating materials; magnetostrictance materials; manometer; resin base filling for decayed tooth; embedding circuit waveguide laser device; fluorescent powder activator; ceramic radio device; electronic computer memory element (magnetic bubble) addictive, glass fibre flux; optical glass addictive.
Lu PET medical instrument probe, not only for general X ray and human body cross section X ray, but also for the latest human cytoscopy; metachromatic display device; special alloy manufacture; neutron activation analysis; petrol cracking catalysis; complex functional crystal; laser; energy cell; fluorescent powder activator.C
Y Principal illuminant materials; imitation jewel; aerosuperalloy; steel and nonferrous alloy addictive; ceramic materials, motor components; laser beam for drilling, cutting and welding; garnet single-crystal chip, electronic microscope screen; high-temperature proton conducting materials; fuel cell; gas sensor; atomic reactor fuel diluent; permanent magnet addictive; degasser used in the electronic industry.
Pm A radioactive element separated from uranium fuel consumed by atomic reactor.It can be used as a heat source. It can provide supplementary energy for vacuum detection and satellite; be used for making Pm cell; as a power source of missile guidance device and clocks; for making portable X ray apparatus; fluorescent powder; navigation beacon.
Sc As compared with Y and La series elements, the ionic radius of Sc is particularly small, the alkalinity of hydroxide is particularly weak as well. Due to its different separating process, it is usually distinguished from other rare earth elements.In the metallurgical industry, Sc is used in the manufacture of alloy addictive to improve the strength, hardness, heat resistance and other features of alloy; in the electronics industry, it is used in the manufacture of various semi-conducting devices; in the chemical industry, it is used in the preparation of alcohol dehydrogenation and dehydrator, as well as a highly efficient catalyst for producing ethylene and producing chlorine with hydrochloric acid waste; in the glass industry, it can be used for making Sc special glass; in the electro-optical industry, Sc Na light is well-known for its high efficiency and precise colour; Sc can be used as a tracer in chemical engineering metallurgical engineering and oceanology; in the medical field, it can be used in the research in cancer treatment.

3. How can rare earth products be categorized?

There are a wide variety of rare earth products which can be mainly divided into two categories: metallurgical products and application products. The former refers to products of rare earth mines and smelters, such as rare earth concentrate, unitary and mixed rare earth oxide, metal and alloy, unitary and mixed rare earth salt etc., altogether over 300 varieties and 500 specifications. The latter refers to all finished products containing rare earth, such as rare earth permanent magnet, rare earth fluorescent powder, rare earth polishing powder, rare earth fertilizer, rare earth laser crystal, rare earth hydrogen-storage materials, etc. Generally speaking, mineral products and primary products (or semi-finished products) are referred to as upstream products; deep processing products (or unitary products, high-purity products) are referred to as middle stream products; application materials and application products (or devices) are referred to as downstream products.

There are several stages involved in the production process of rare earth products. From the sourcing of raw materials, processing of materials and components, to the making of final products, all require critical technology specifically for the respective stages of the production process. As it's getting closer to the final products, the technology so required will be getting more sophisticated, and, as it should be, the relevant products will be of higher added value.

4. How about the reserve and distribution of rare earth ores?

According to the statistics of US Mineral Department in 1998, there was a reserve of exploitable rare earth ores at approximately 45 million tonnes (REO) prospected all over the world. Of which 36 million tonnes (REO) were located in China, representing about 80% of the global reserves. Second to China was the United States, which have reserves at about 5.5 million tonnes (REO). The remaining reserves were located in other countries such as India, Australia, Russia and Brazil.

China's rare earth ores can be broadly divided into the north ore and the south ore. The north ore mainly refers to the fluorocarbon cerium ore co-existing with iron ores in Baotou, Inner Mongolia which principally contains four light rare earth elements, i.e. La, Ce, Pr and Nd. The south ore mainly comprises the ion absorption ores in Jiangxi and Guangdong, from which various elements of light rare earth, middle rare earth and heavy rare earth can be separated. Such excellent rare earth ores have only been found in China so far. Based on an annual output of 50,000 tonnes (REO), the existing rare earth reserves can still be exploited for more than 800 years.

China ranks No. 1 in terms of reserves, output and consumption all over the world, with its technology in production, refining and research and development reaches international advanced levels. The United States and Japan rank No.2 and No.3 respectively in terms of rare earth consumption.

Refractory Products

1. What are refractory products?

Refractory products refer to functional materials which can resist high temperature or even ultra-high temperature. They are widely used in various high temperature heat treatment equipment, such as steels-melting kiln, glass kiln and cement kiln. The quality of refractory products directly affects the usable life of kilns and the quality of the final industrial output. Refractory products are made from various natural minerals such as silica, dolomite, graphite, zircon, magnesia, high aluminium ore and chrome ore through numerous technical refining processes. They have valuable features such as high-heat insulation, high-heat resistance, high strength, high hardness, good volume stability, oxidation resistance, excellent complexity, wear resistance, corrosion resistance, etc.. Some refractory products even have special features such as high ventilation, heat conduction and extreme hardness.

2. Any differences between shaped and unshaped refractory products?

Shaped refractory products can be pressed into bricks and are, generally used in building heat treatment equipment such as metallurgical kilns. Unshaped refractory products refer to fire-resistant casting materials. They can be moulded into whatever shapes and are suitable for building different high temperature furnaces and using as the lining in different heat treatment furnaces.

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