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Rare earth alloy
Light rare earth
Rare earth metals
Medium rare earth
Heavy rare earth
Mixed rare earth
Rare earth lanthanum (La), cerium (Ce), praseodymium (Pr), neodymium (Nd), promethium (Pm), samarium (Sm), europium (Eu), gadolinium (Gd), terbium (Tb), dysprosium (Dy), holmium (Ho), erbium (Er), thulium (Tm), ytterbium (Yb), lutetium (Lu), scandium (Sc) and yttrium (Y), a total of 17 elements. The English name is Rare Earth. Rare earth metals are generally soft, malleable, malleable, powdery and highly reactive at high temperatures. This group of metals has strong chemical activity, and has a strong affinity for hydrogen, carbon, nitrogen, oxygen, sulfur, phosphorus and halogen. It is easy to be oxidized in the air. The surface of heavy rare earth and scandium and yttrium is easy to form an oxide protective layer at room temperature. Rare earth elements can be divided into light rare earth and heavy rare earth, mainly in the form of rare earth oxides. China, Russia, the United States and Australia lead the world in rare earth reserves. Rare earth is mainly used in petroleum, chemical industry, metallurgy, textile, ceramic glass, permanent magnet materials and other fields, known as "industrial monosodium glutamate", "industrial vitamin" and "the mother of new materials", is a precious strategic metal resources.
Rare earth (Rare earth) is the general name of the lanthanide series and scandium and yttrium in the periodic table of elements. There are 250 rare earth minerals found in nature.
Rare earths were first discovered by Finnish chemist John Gadolin. In 1794, he isolated the first rare earth "element" (yttrium, or Y2O3) from a heavy bituminous ore.
Because rare earth minerals were found in the 18th century, at that time, only a small amount of insoluble oxides could be obtained by chemical process. In history, it was customary to call such oxides "earth", hence the name rare earth. [1]
Industrial vitamin application petroleum, chemical industry, metallurgy, textile, ceramics and permanent magnet materials distribution countries China, India, the United States and so on
directory
1 Component Elements
2 Physical and chemical properties
3 Common Types
Raw ore
▪ finished product
4 Preparation method
beneficiation
determination
▪ decomposition
▪ smelting
▪ Purification
5 Application Fields
▪ Military
▪ Metallurgical industry
▪ Petrochemical industry
▪ glass ceramics
▪ Agriculture
6. China's Development
Current situation
▪ Management approach
7. The first strategic purchase and storage of rare earth was launched
8 Resource Distribution
▪ Characteristics of rare earth
state
9 Global Total
▪ China
▪ Turkey
▪ United States
▪ India
▪ Russia
▪ Australia
▪ Canada
▪ South Africa
▪ Malaysia
▪ Egypt
▪ Brazil
10 Rare Earth Wars
▪ Japan
▪ United States
▪ European Union
▪ India-Japan cooperation
▪ Real purpose
▪ Elimination of tariffs
11 Rare earth poisoning
Component editing broadcast
Rare earth and materials
Rare Earth and Materials (14 sheets)
According to the atomic electron layer structure and physical and chemical properties of rare earth elements, as well as their co-occurrence in minerals and the characteristics of different ionic radii, 17 rare earth elements are usually divided into two groups:
Light rare earths include: lanthanum, cerium, praseodymium, neodymium, promethium, samarium, europium.
Heavy rare earths include gadolinium, terbium, dysprosium, holmium, erbium, thulium, ytterbium, lutetium, scandium and yttrium.
The position of rare earth elements in the periodic table
The position of rare earth elements in the periodic table
Classification by extraction separation:
Light rare earth (P204 weak acidity extraction) -- lanthanum, cerium, praseodymium, neodymium;
Rare earths (P204 low acidity extraction) -- Samarium, europium, gadolinium, terbium and dysprosium;
Heavy rare earths (pH extraction in P204) -- holmium, erbium, thulium, ytterbium, lutetium, yttrium.
Physical and chemical properties edited broadcast
One is the absence of sulfides and sulfates (very rarely), which suggest that rare earth elements are oxygen-loving.
Second, the silicates of rare earth are mainly island-like, without layer, frame and chain structure.
Thirdly, some rare earth minerals (especially complex oxides and silicates) are amorphous.
The fourth is the distribution of rare earth minerals, which are mainly silicates and oxides in magmatic rocks and pegmatite, fluorocarbates and phosphates in hydrothermal deposits and weathering crust deposits. Most yttrium-rich minerals occur in granite-like rocks, pegmatite and gas-hydrothermal deposits.
Fifth, rare earth elements are often symbiosis in the same mineral due to their similar atomic structure, chemical and crystal chemical properties, that is, cerium rare earth and yttrium rare earth elements often co-exist in a mineral, but these elements do not coexist in equal quantities, some minerals are dominated by cerium rare earth, while some minerals are dominated by yttrium.
Among more than 250 rare earth minerals and minerals containing rare earth elements have been discovered, there are only more than 10 industrial minerals suitable for the present conditions of separation and metallurgy.
Common types edited broadcast
Raw ore
monazite
Monazite (Monazite) also known as phosphorous cerium lanthanite.
Chemical composition and properties: (Ce, La, Y, Th) [PO4]. The composition varies greatly. The content of rare earth oxides in mineral composition can reach 50 ~ 68%. The homomorphic mixtures are Y, Th, Ca, [SiO4] and [SO4]. Monazite dissolves in H3PO4, HClO4, H2SO4.
Crystal structure and morphology: monoclinic crystal system, rhombic columnar crystal class. Crystal into plate, crystal surface often striped, sometimes columnar, cone, granular.
Physical properties: yellowish brown, brown, red, sometimes green. Translucency to transparency. Streaks white or light reddish yellow. It has a strong glass luster. Hardness 5.0 ~ 5.5. It is brittle. Specific gravity is 4.9 ~ 5.5. Electromagnetism is moderately weak. It glows green in X-rays. It does not glow under cathode rays.
Formation state: occurring in granite and granite-pegmatite; Rare metal carbonate rocks; Dolomite and quartzite; In Yunxia syenite, aegirite and alkaline syenite pegmatite; In the Alps; In mixed rock; And weathered crust and placer.
Purpose: Mainly used to extract rare earth elements.
Origin: The main resources of monazite with economic mining value are alluvial or coastal placer deposits. The most important coastal placer deposits are off the coast of Australia, Brazil and India. In addition, Sri Lanka, Madagascar, South Africa, Malaysia, China, Thailand, South Korea, North Korea and other places contain monazite heavy placer deposits.
Production of monazite has declined in recent years, mainly because thorium element in ore is radioactive and harmful to the environment.
fluocerite
Chemical composition properties: (Ce, La) [CO3]F. Mechanical mixture of SiO2, Al2O3, P2O5. Bastesite is soluble in dilute HCl, HNO3, H2SO4 and H3PO4.
Crystal structure and morphology:
Hexagonal system. Ditripartite dipyramidal crystals. The crystals are hexagonal columns or plates. Fine granular aggregate.
Physical properties: yellow, reddish brown, light green or brown. Glass luster, grease luster, stripes are white, yellow, transparent to translucent. Hardness 4 ~ 4.5, brittle, specific gravity 4.72 ~ 5.12, sometimes with radioactivity, weak magnetic. Transparent in flakes, colorless or yellowish in transmitted light, and not luminous in cathode rays.
Formation state: occurs in rare metal carbonate rocks; Granite and granite-pegmatite; In a quartz vein associated with granitic syenite; In quartz-iron-manganese carbonate dike; In the placer.
Use: It is an important mineral raw material for extracting cerium rare earth elements. Cerium is used in alloys to improve the elasticity, toughness and strength of metals, and is an important part in jet aircraft, missiles, engines and heat-resistant machinery. It can also be used as a protective shell against radiation. Cerium is also used to make colored glass.
phosphoyttriite
Chemical composition and properties: Y[PO4]. The composition is Y2O 361.4% and P2O5 38.6%. Rare earth elements of yttrium group were mixed, including ytterbium, erbium, dysprosium and gadolinium. Elements such as zirconium, uranium and thorium are substituted for yttrium, accompanied by silicon instead of phosphorus. In general, the content of uranium in phosphoyttriite is greater than thorium. The chemical properties of phosphoyttrium are stable. Crystal structure and morphology: tetragonal system, compound tetragonal dipyramidal type, granular and massive.
Physical properties: yellow, reddish-brown, sometimes yellow-green, brown or hazel. Streaks light brown. Glass luster, grease luster. Hardness 4 ~ 5, specific gravity 4.4 ~ 5.1, with weak polychromism and radioactivity.
Formation state: mainly produced in granite, granite-pegmatite. It is also found in alkaline granite and related deposits. It is also produced in placer mines. Purpose: When enriched in large quantities, it can be used as mineral raw material for refining rare earth elements.
Lanthanum vanadium epidotite
A joint research team from Yamaguchi University, Ehime University and the University of Tokyo said in a statement that they had discovered a new type of mineral containing rare earths in Mie Prefecture. Rare earth plays a "Midas touch" role in transforming traditional industries and developing high-tech fields. The new mineral was discovered in the mountains of Ise City in Mie Prefecture in April 2011. It is a special kind of brown epidote containing the rare earth lanthanum and the rare metal vanadium. On March 1, 2013, the mineral was recognized as a new mineral by the International Mineralogical Association and named "lanthanum vanadium epidotite".
Finished product
Rare earth chloride carbonate
These are the two main primary products in the rare earth industry, and generally speaking, there are currently two main processes to produce these two products.
One process is concentrated sulfuric acid roasting, in which rare earth concentrate is mixed with sulfuric acid in a rotary kiln. The calcined ore is leached with water, and the soluble rare earth sulfate enters the aqueous solution, which is called leach solution. Then add ammonium bicarbonate to the leaching solution, rare earth as carbonate precipitation, after filtration to obtain rare earth carbonate.
Another process is called caustic soda process, referred to as alkali process. Generally, 60% of rare earth concentrate is mixed with concentrated lye and fused at high temperature. The rare earth concentrate is decomposed and the rare earth becomes rare earth hydroxide. The alkali cake is washed to remove sodium salt and excess alkali, and then the washed rare earth hydroxide is dissolved in hydrochloric acid. The filtered rare earth chloride solution is concentrated and crystallized to produce solid rare earth chloride.
Phosphorite rare earth
In addition to rare earth minerals, a large part of rare earth elements coexist with apatite and phosphorite minerals. Because the ionic radii of rare earth (0.848 ~ 0.106 nm) and Ca2+ (0.106 nm) are very close, rare earth exists in phosphate rock in a homomorphic manner. The world's total phosphate ore reserves are about 100 billion tons, with an average rare earth content of 0.5 ‰, and the estimated total amount of rare earth associated with the world's phosphate ore is 50 million tons.
In view of the characteristics of low rare earth content and special occurrence state in ore, a variety of recovery processes have been carried out at home and abroad, which can be divided into wet method and hot method:
Wet method, according to the decomposition of different acids can be divided into method, hydrochloric acid method, sulfuric acid method. There are many kinds of rare earth recovery from phosphorus chemical process, which are closely related to phosphate ore processing.
In the process of thermal production, rare earth mainly enters into silicate slag, which can be decomposed and leach by a large amount of hydrochloric acid or filtered to remove silica, and then extracted by TBP to recover rare earth. The recovery rate of rare earth can reach 60%.
With the continuous utilization of phosphate ore resources, it is turning to the development of low-quality phosphate ore. Sulfuric acid wet-process phosphoric acid process has become the mainstream method of phosphorus chemical industry, and the recovery of rare earth in sulfuric acid wet-process phosphoric acid has become a research hotspot. In the process of sulfuric acid wet phosphoric acid production, the process of rare earth extraction with organic solvent is more advantageous than the earlier developed methods by controlling the enrichment of rare earth in phosphoric acid.
Mixed rare earth
Metal produced by molten salt electrolysis from rare earth ores containing oxides or chlorides of lanthanum, cerium, praseodymium, neodymium and a small amount of samarium, europium and gadolinium. The total rare earth is more than 98%, cerium is more than 48% light rare earth. It is easy to oxidize to black in air, and can react with water at room temperature. Can be used as flint, alloy additives, hydrogen storage materials.
Preparation method edit broadcast
beneficiation
Beneficiation is a mechanical processing process that utilizes the differences between the physical and chemical properties of various minerals composed of ore, adopts different beneficiation methods, with the help of different beneficiation processes and different beneficiation equipment to enrich useful minerals in the ore, remove harmful impurities, and make it separate from gangue minerals.
At present, the content of rare earth oxides in the rare earth ores mined by China and other countries in the world is only a few percent, or even lower. In order to meet the production requirements of smelting, rare earth minerals are separated from gangue minerals and other useful minerals through beneficiation before smelting, so as to increase the content of rare earth oxides and obtain rare earth concentrates that can meet the requirements of rare earth metallurgy. The mineral processing of rare earth ore generally adopts flotation method, and is often supplemented by gravity separation and magnetic separation to form a variety of combination of mineral processing processes.
The rare earth deposit in Bayan Obo Mine in Inner Mongolia is a carbonate rock type deposit of iron dolomite, with rare earth minerals associated with the main components of iron ore (in addition to bastnaite and monazite, there are several niobium and rare earth minerals). The ore produced contains about 30% iron and about 5% rare earth oxides. After crushing large ores in the mine, they are transported by train to the concentrator of Baotou Iron and Steel Group Company. The task of the concentrator is to increase Fe2O3 from 33% to more than 55%, first grinding and grading on the conical ball mill, and then using the cylinder magnetic separator to select 62 ~ 65%Fe2O3 (iron oxide) primary iron concentrate. The tailings were further flotation and magnetic separation to obtain a secondary iron concentrate containing 45% Fe2O3 (iron oxide) or more. Rare earth is enriched in flotation foam with a grade of 10 ~ 15%. Coarse concentrate with 30% ReO content can be selected by shaker, and rare earth concentrate with more than 60% ReO can be obtained after reprocessing by beneficiation equipment.
determination
1. Absorb 15ml filtrate from the color developing solution, add 7ml 5% oxalic acid and 3ml phosphine azo into a 50ml conical bottle, and shake well. This is the developing package solution.
2, the reference solution and color solution after the same operation, then add 1-2 drops of sodium diphosphate (drop two drops can) solution, faded as the reference liquid (blank liquid), poured into the 2cm colorimeter, wavelength 660nm, measure its absorbance and content. (Can be done in Aisle 2). Note: The color developing solution is ink black.
decomposition
Rare earths in rare earth concentrate are generally in the form of carbonate, fluoride, phosphate, oxide or silicate which are insoluble in water. Rare earth must be transformed into compounds soluble in water or inorganic acid through various chemical changes. After dissolution, separation, purification, concentration or burning and other processes, various mixed rare earth compounds such as mixed rare earth chloride are made as raw materials for products or separation of single rare earth. Such a process is called rare earth concentrate decomposition, also known as pretreatment.
There are many methods for the decomposition of rare earth concentrates. Generally speaking, they can be divided into three categories: acid, alkali and chlorination. Acid decomposition is divided into hydrochloric acid decomposition, sulfuric acid decomposition and decomposition. Alkali decomposition is divided into sodium hydroxide decomposition or sodium hydroxide melting or soda roasting method. Generally, the appropriate technological process is selected according to the types, grade characteristics and product schemes of concentrates, which are convenient for the recovery and comprehensive utilization of non-rare earth elements, conducive to labor health and environmental protection, and economical and reasonable.
At present, nearly 200 kinds of scattered elemental minerals have been found, but because of the rarity and lack of rich integrated independent deposits with industrial exploitation, only rare independent germanite, selenite and tellurite have been found, but the deposit scale is not large.
Sulfuric acid dissolution
Cerium group (sulfate compound salt is insoluble) - lanthanum, cerium, praseodymium, neodymium and promethium;
Terbium group (slightly soluble with double sulfate) -- Samarium, europium, gadolinium, terbium, dysprosium and holmium;
Yttrium Group (soluble by double sulfate) -- yttrium, erbium, thulium, ytterbium, lutetium and scandium.
smelting
There are two methods of rare earth smelting, namely hydrometallurgy and pyrometallurgy.
Hydrometallurgy is a form of chemical metallurgy, and the whole process is mostly in solution and solvent. For example, the decomposition of rare earth concentrate, separation and extraction of rare earth oxides, rare earth compounds and single rare earth metals are the chemical separation processes such as precipitation, crystallization, REDOX, solvent extraction and ion exchange. At present, organic solvent extraction is widely used, which is a general process for industrial separation of high purity single rare earth elements. Hydrometallurgy process is complex, the product purity is high, and the application of the finished product is broad.
Pyrometallurgical process is simple and productivity is high. Rare earth pyrosmelting mainly includes rare earth alloy by silicon thermal reduction, rare earth metal or alloy by molten salt electrolysis, rare earth alloy by metal thermal reduction, etc. The common characteristic of pyrometallurgy is that it is produced at high temperature.
Fractional step method
From yttrium (Y) in 1794 to lutetium (Lu) in 1905, all single separations of naturally occurring rare earth elements, as well as radium, discovered by the Curies, were made in this way. The fractional method is used to separate and purify compounds using differences in the ease with which they are dissolved in solvents (solubility). The operation procedure of the method is: it will contain two rare earth elements
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