Rare earth metals

from Wikipedia, the free encyclopedia
Rare earth metals in the periodic table of the elements (outlined in bold)

The rare earth metals include the chemical elements of the 3rd subgroup of the periodic table (with the exception of actinium ) and the lanthanoids - a total of 17 elements. According to the definitions of the inorganic nomenclature , this group of chemically similar elements is called rare earth metals . In German there is also the term rare earth elements and, appropriately, the abbreviation SEE , based on the English REE ( Rare Earth Elements ).

Designation and classification

Rare earth elements
easy
( LREE )		 Z heavy
( HREE )		 Z
Scandium 21st yttrium 39
Lanthanum 57 Gadolinium 64
Cerium (ger .: Cerium) 58 Terbium 65
Praseodymium 59 Dysprosium 66
Neodymium 60 holmium 67
promethium 61 Erbium 68
Samarium 62 Thulium 69
Europium 63 ytterbium 70
lutetium 71

The often used abbreviated term rare earths instead of rare earth metals is misleading. This name comes from the time of the discovery of these elements and is based on the fact that they were first found in rare minerals and isolated from them in the form of their oxides (formerly called "earths"). Only promethium , a short-lived radioactive element, is really rare in the earth's crust. Some of the rare earth metals ( cerium - also called cerium, yttrium and neodymium ) occur more frequently in the earth's crust than, for example, lead , copper , molybdenum or arsenic . Thulium , the rarest stable element of the rare earth metals, is still more abundant than gold or platinum .

The designation as rare is justified insofar as larger deposits of economically exploitable minerals are actually rare. The elements usually only occur in small amounts, in a great number of widely scattered minerals and as admixtures in other minerals. A large part of the industrial extraction of rare earth metals therefore takes place as a by-product through chemical processing in the extraction of other, more concentrated metals from their ores.

A distinction is also made between light and heavy rare earth elements, the exact classification is disputed. In geochemistry , often only the lanthanoids are meant when rare earths are mentioned. Due to different fractionation properties, scandium and yttrium are not considered in the geochemical modeling of rare earths.

properties

All lanthanides (except radioactive promethium) at a glance

Physical Properties

The spectroscopic properties of rare earths are of particular interest . In the solid state , in contrast to semiconductors , for example , they have a discrete energy spectrum. This is due to the special structure of the electron shell . Optical transitions take place within the 4f shell (except for scandium and yttrium), which is shielded from the outside by the larger occupied 5s, 5p and 6s shells. A band structure can not develop for the f orbitals due to this shielding . The absorption lines are exposed due to the different electronic surroundings in the crystal (crystal field) for the individual ions of the elements . The inhomogeneous line width ranges, depending on the crystal, from a few hundred gigahertz to around ten gigahertz.

In the atomic state, however, most of these transitions are "forbidden" (see Forbidden Transition ). In the solid state, however, the crystal field cancels these atomic prohibitions to a certain extent through other transitions. The transition probabilities are nevertheless low.

Chemical properties

The similarity of the chemical properties of the rare earth metals makes their separation complex and expensive. However, it is often sufficient to use inexpensive mischmetal . It is a mixture of rare earth metals that is produced in the processing of rare earth ores such as monazite . Rare earth metals are among the lithophilic and incompatible elements .

Position in the periodic table

1
H. 		2
He
3
li 		4
Be 		5
B 		6
C 		7
N. 		8
O 		9
F. 		10
Ne
11
Well 		12
mg 		13
Al 		14
Si 		15
p 		16
pp 		17
cl 		18
ares
19
K 		20
approx 		21
Sc 		22
Ti 		23
V 		24
Cr 		25
mn 		26
feet 		27
Co 		28
Ni 		29
Cu 		30
notes 		31
Ga 		32
Ge 		33
As 		34
Se 		35
Br 		36
kr
37
Rb 		38
Sr 		39
Y 		40
Zr 		41
Nb 		42
Mon 		43
Tc 		44
Ru 		45
Rh 		46
Pd 		47
Ag 		48
Cd 		49
in 		50
Sn 		51
Sb 		52
te 		53
I. 		54
Xe
55
Cs 		56
Ba 		57
La 		58
Ce 		59
Pr 		60
Nd 		61
pm 		62
Sm 		63
Eu 		64
Gd 		65
p 		66
Dy 		67
Ho 		68
he 		69
Tm 		70
yb 		71
Lu 		72
Hf 		73
days 		74
W 		75
Re 		76
Os 		77
Ir 		78
Pt 		79
Au 		80
ed 		81
Tl 		82
Pb 		83
bi 		84
Po 		85
at 		86
para
87
Fr 		88
Ra 		89
Ac 		90
th 		91
Pa 		92
U 		93
Np 		94
Pu 		95
am 		96
cm 		97
Bk 		98
Cf 		99
it 		100
m 		101
Md 		102
No. 		103
Lr 		104
para 		105
Db 		106
Sg 		107
hours 		108
ms 		109
m 		110
Ds 		111
Rg 		112
cn 		113
Nh 		114
bottles 		115
Mc 		116
Lv 		117
Ts 		118
above
year Element / mineral Explorer Naming
1787 Yttria CA Arrhenius Location: Ytterby
1794 Gadolinite J. Gadolin Person: Johan Gadolin
1751 Cerite AF Cronstedt Planetoid: Ceres
1804 cerium JJ Berzelius ,
W. von Hisinger
1839 Samarskit MH Klaproth ,
G. Rose 		Person: Colonel Samarsky
1839 Lanthanum CG Mosander Property: to be hidden
1842 Didym Feature: twins
1843 Erbium
from 1864: Terbium 		Location: Ytterby
1843 Terbium
from 1864: Erbium
1878 ytterbium de Marignac Location: Ytterby
Property: between
erbium and yttrium
1879 Samarium de Boisbaudran Mineral: Samarskite
1879 Scandium LF Nilson Location: Scandinavia
1879 Thulium PT Cleve Location: Scandinavia
old name: Thule
1879 holmium Location: Stockholm
1886 Dysprosium de Boisbaudran Property:
Greek: inaccessible
1886 Gadolinium de Marignac Person: J. Gadolin
1886 Praseodymium A. von Welsbach Feature: green twin
1886 Neodymium Feature: new twin
1901 Europium E.-A. Demarçay Location: Europe
1907 lutetium G. Urbain ,
A. von Welsbach 		Location: Paris (lat .: Lutetia)
1947 promethium J. Marinsky ,
L. Glendenin ,
C. Coryell 		Say: Prometheus

history

In 1787, Carl Axel Arrhenius , a lieutenant in the Swedish army, discovered an unusual specimen of black ore near the feldspar mine at Ytterby . In 1794, Johan Gadolin , a Finnish professor at the University of Åbo , isolated around 38 percent of a new, previously unrecognized "earth" (oxide). Although Arrhenius named the mineral ytterite , Anders Gustaf Ekeberg called it gadolinite . Shortly afterwards, in 1803, the German chemist Martin Heinrich Klaproth and Jöns Jakob Berzelius and Wilhelm von Hisinger in Sweden independently isolated a similar "earth" from an ore that Axel Frederic Cronstedt had found in a mine near Bastnäs in Sweden in 1751 . This mineral was named cerite and the metal cerium , after the planetoid Ceres , which was just discovered at the time .

Carl Gustav Mosander , a Swedish surgeon, chemist and mineralogist, carried out experiments between 1839 and 1841 to thermally decompose a sample of nitrate obtained from cerite. He leached the product with dilute nitric acid, identified the insoluble product as cerium oxide and finally won two new "earths" from the solution, Lanthana (to be hidden) and Didymia (twin brother of Lanthana). In a similar way, Mosander isolated three oxide fractions from the original yttrium oxide in 1843: a white (yttrium oxide), a yellow (erbium oxide) and a pink (terbium oxide).

These observations led to a period of intense research into both ceria and yttria well into the 1900s, involving prominent researchers of the time. There has been duplication, inaccurate reports, dubious claims to discovery, and countless examples of confusion due to a lack of communication and characterization and separation methods.

After 1850, the newly discovered spectroscopy served to prove the presence of the known elements and to identify new ones. In 1864, Marc Delafontaine , a Swiss-American chemist, used the method to unambiguously identify yttrium, terbium and erbium as elements. He mixed up the names of terbium and erbium; the name change because of this mistake was never reversed.

In 1885 Carl Auer von Welsbach began investigating Didym. At that time it was already suspected that this was not a single element. However, previous efforts to separate the individual elements had not been successful. Auer used his method of fractional crystallization instead of fractional precipitation. This enabled him to separate the supposed didymium into praseodymium and neodymium. In 1907 he published experimental results on the existence of two elements in ytterbium, which he called Aldebaranium and Cassiopeium. After the longest priority dispute in the history of chemistry with the French chemist Georges Urbain , these are referred to as ytterbium and lutetium.

Lutetium closed the chapter in the history of the discovery of the naturally occurring rare earth metals, which had lasted more than a century. Even if all naturally occurring rare earth metals had been discovered, the researchers at the time were not aware of this. So both Auer and Urbain continued their work. The theoretical explanation of the great similarity of the properties of the rare earth metals and the maximum number of these only came later with the development of atomic theory . The ordinal number was introduced by van den Broek in 1912 . Henry Growyn and Henry Moseley discovered in 1913 that there is a mathematically representable relationship between the atomic number of an element and the frequency of the X-rays emitted at an anticathode of the same. Urbain then subjected all recently discovered rare earth elements to the Moseley test and confirmed that they were real elements. The range of rare earth elements from lanthanum with atomic number 57 to lutetium with 71 was established, but 61 was not yet known.

In 1941, researchers at the University of Ohio irradiated praseodymium, neodymium, and samarium with neutrons, deuterons, and alpha particles, creating new radio activities that were most likely due to that of element number 61. The formation of element 61 was also claimed by Wu and Segrè in 1942 . Chemical evidence was obtained in 1945 at the Clinton Laboratory, later the Oak Ridge National Laboratory, by Marinsky, Glendenin and Coryell, who isolated the element from the products of the nuclear fission of uranium and the neutron bombardment of neodymium using ion exchange chromatography . They named the new element promethium .

From 1963 to 1995 Allan Roy Mackintosh made decisive contributions to the understanding of rare earths in terms of atomic and solid-state physics.

Occurrence

Rare earth ores (Baotou, China)
Rare earth minerals 1.jpg
Rare earth minerals 2.jpg
Rare earth minerals 3.jpg
Rare earth minerals 4.jpg

The largest deposits of rare earths are in China in Inner Mongolia (2.9 million tons, for example Bayan Obo mine , ore content of 3–5.4 percent of the rare earth metals). The largest known deposit outside of China with at least 1.4 million usable tons is Mount Weld in Western Australia. There are also large deposits in Greenland with a deposit of 2.6 million tons, for which only a pilot plant has been operated so far. Large deposits have also been discovered in Canada .

The share of China in global production was given as around 97.5% in 2014; it fell to 71% by 2018. 12% was won in Australia, 9% in the US. In addition to the occurrence of rare earths in the USA ( Mountain Pass , California) there are other already developed ones in India, Brazil and Malaysia. South Korea intends to promote rare earths in cooperation with Vietnam in the future. Japanese scientists discovered larger amounts of rare earths in the Pacific in mid-2011. The largest deposit to date was found in North Korea in 2013 . The Jongju deposit is believed to contain around 216 million tons.

In 2012, exploration was carried out in Germany by the company Seltenerden Storkwitz AG : For the deposit near Storkwitz (district of Delitzsch , Saxony ), resource estimates by geologists from the 1980s were confirmed to a depth of 600 meters. It is a resource of 4.4 million tons of ore with 20,100 tons of rare earth compounds (mostly oxides) with grades of 0.45 percent. In 2017, however, the project was discontinued as not being economical.

The most important ores of the rare earth metals are monazite and bastnasite . The SE grade of the ore from Mount Weld is reported as 10 percent and that of Mountain Pass as 8-12 percent.

Worldwide production and reserves (in thousands of tons)
country 2010 2011 2012 2013 2014 2015 2016 2017
Reserves
(as of 2017)
China People's RepublicPeople's Republic of China China 130 105 100 095 095 105 105 105 44,000
United StatesUnited States United States 000 000 000.8 005.5 007th 004.1 000 000 01,400
IndiaIndia India 002.8 002.8 002.9 002.9 003.0 k. A. 001.7 001.5 06,900
AustraliaAustralia Australia 000 002.2 003.2 002.0 002.5 010 014th 020th 03,400
RussiaRussia Russia k. A. k. A. k. A. 002.5 002.5 002.5 003.0 003.0 (CIS, 2012 :) 18,000
MalaysiaMalaysia Malaysia 000.03 000.28 000.10 000.18 000.2 000.2 000.3 000.3 30th
BrazilBrazil Brazil 000.55 000.25 000.14 000.33 / / 001.1 002.0 022,000
ThailandThailand Thailand k. A. k. A. k. A. k. A. k. A. k. A. 000.8 001.6 k. A.
VietnamVietnam Vietnam k. A. k. A. k. A. k. A. k. A. k. A. 000.3 000.1 22,000
Total (rounded) 133 111 110 111 110 124 126 130 120,000

On the earth's moon there are deposits of KREEP minerals, which contain rare earths in small amounts. Rare earth metals are present on other objects in space, including near-earth objects (NEOs). There are theoretical considerations for asteroid mining .

None of the rare earth metals occurs in nature, but there is always a mixture of rare earths. For this reason, no uniform chemical formula can be given for the corresponding minerals (e.g. allanite ). It has therefore become common in mineralogy to state the elements of the rare earths in their sum and to abbreviate them in the corresponding chemical formula with SEE (rare earth elements) or REE (from English rare earth elements ). If possible, the designation Ln should be chosen for the lanthanoids or (Y, Sc, Ln) for the rare earth metals.

Extraction

The pure metals are predominantly obtained by fused-salt electrolysis of the chlorides or fluorides . Before that, however, the corresponding compounds have to be separated from the ores, which, in addition to other compounds, always contain mixtures of the rare earths, using sometimes complex separation processes. In the first step, the ores are digested by treating them with alkalis or acids ; in some cases the ores, such as monazite , are also subjected to high-temperature chlorination, which results in a mixture of chlorides. In a further step, the salts obtained from the digested material are subjected to a separation process. The following are possible:

Production facilities for liquid-liquid extraction are almost exclusively in China. In Europe only Silmet in Estonia and Solvay in La Rochelle are still active.

Biological process

A bioleaching process to extract rare earth metals from phosphorus gypsum and electronic scrap is based on an acid mixture that is produced by the bacterium gluconobacter oxydans and u. a. Contains gluconic acid .

use

Rare earths are used in many key technologies. Europium was required in tube and plasma screens for the red component in the RGB color space . Neodymium is used in an alloy with iron and boron to manufacture permanent magnets . These neodymium magnets are used in permanent -magnet electric motors, generators in wind turbines and also in electric motors in vehicle hybrid drives. Lanthanum is required for alloys in accumulators . 13 percent of the rare earth metals are used for polishing, around 12 percent for special glasses and 8 percent for the lamps in plasma and LCD screens, for fluorescent lamps (to a lesser extent for compact fluorescent lamps ) and radar devices. Rare earth metals are used in medical-diagnostic radiology to add contrast media to magnetic resonance imaging ( magnetic resonance imaging ).

More recent studies show that the oxides of the lanthanum series have intrinsically hydrophobic properties after sintering . Due to their high temperature resistance, high abrasion resistance and their hydrophobic properties, there are other possible uses in this regard (e.g. steam turbines and aircraft engines).

Further examples can be found in the table using the lanthanoids and in the articles for the respective elements. The consumption of 124,000 tons in 2009 is offset by an expected demand for 2012 of 189,000 tons.

Z Surname etymology selected uses
21st Sc Scandium from Latin Scandia , Scandinavia , where the first ore was discovered Stadium lighting, fuel cells , racing bikes , X-ray technology , lasers
39 Y yttrium after the discovery site of the rare earth ore at Ytterby , Sweden Fluorescent lamps , LCD and plasma screens , LEDs , fuel cells , Nd: YAG lasers
57 La Lanthanum from greek lanthanum to be hidden. Nickel-metal hydride batteries (e.g. in electric and hybrid cars , laptops ), catalysts ,
soot particle filters , fuel cells , glasses with a high refractive index
58 Ce cerium after the dwarf planet Ceres . Car catalytic converters , soot particle filters , ultraviolet radiation protective glasses, polishing agents
59 Pr Praseodymium from Greek prásinos ' leek green', didymos 'double' or 'twin' Permanent magnets , aircraft engines, electric motors , glass and enamel coloring
60 Nd Neodymium from Greek neos 'new' and didymos 'double' or 'twin' Permanent magnets (e.g. in electric motors , wind turbines ,
magnetic resonance imaging scanners , hard drives ), glass coloring, lasers , CD players
61 Pm promethium of Prometheus , a titan of Greek mythology Luminous numbers , heat sources in space probes and satellites ( radioactive element)
62 Sm Samarium after the mineral Samarskit , which in turn is named after the
mining engineer WM Samarski 		Permanent magnets (in dictation machines, headphones, hard disk drives),
space travel, glasses, lasers, medicine
63 Eu Europium next to americium the only element named after a continent LEDs, fluorescent lamps, plasma TV (red fluorescent)
64 Gd Gadolinium after Johan Gadolin (1760-1852), the namesake of gadolinite Contrast media ( magnetic resonance imaging ), radar screens (green fluorescent material),
nuclear fuel elements
65 Tb Terbium after the Swedish site of Ytterby Phosphors, permanent magnets
66 Dy Dysprosium from Greek δυσπρόσιτος 'inaccessible' Permanent magnets (e.g. wind turbines), phosphors, lasers, nuclear reactors
67 Ho holmium from Stockholm (lat. Holmia ) or a derivative of the chemist Holmberg High-performance magnets, medical technology, lasers, nuclear reactors
68 He Erbium after the Swedish site of Ytterby Lasers (medicine), fiber optic cables
69 Tm Thulium to Thule , the mythical island on the edge of the world Fluorescent lamps, X-ray technology, televisions
70 Yb ytterbium after the Swedish site of Ytterby Infrared laser , chemical reducing agent
71 Lu lutetium after the Roman name of Paris , Lutetia Positron emission tomograph

environmental issues

Rare earths are broken down using acids that wash the metals out of the boreholes. The poisoned mud remains behind. In addition, there are large amounts of residues that contain toxic waste (thorium, uranium, heavy metals, acids, fluorides). The mud is stored in artificial ponds, which are by no means safe, especially in China due to the lack of environmental regulations. In addition to this danger to the groundwater, there is a permanent risk of radioactivity escaping, as many rare earth ores contain radioactive substances.

World production of rare earth metals (1950–2000)

World market problems

The amount of rare earths extracted worldwide in 2010 was just over 133,000 tons; In 2012, the global output fell to 110,000 tons (in China alone from 130,000 tons in 2010 to 100,000 tons in 2012). This corresponds to almost 120th part of the worldwide annual copper production of 15 million tons. To assess the world market situation, it makes sense to differentiate between light and heavy rare earths (see above section "Designation and classification").

The extraction of rare earths is very expensive. The USA was the main producing country until the 1990s; later, because of the lower costs in the People's Republic of China (hereinafter: China), production in the USA became unprofitable. China extracted around 119,000 tons in 2006 (five times as much as in 1992) and now dominates the world market (2007: 95 percent of global extraction, 2010: 97 percent, 2011: 95 percent, 2013: 92 percent, 2018: 71 Percent).

China limits exports: a quota of 30,300 tons was set for 2010, so that only 8,000 tons remained for the second half of the year (compared to 28,000 tons in the second half of 2009). In 2011, the light rare earths neodymium, lanthanum, cerium and europium were subject to an export quota of 35,000 tonnes, and the heavy rare earths yttrium, thulium and terbium were subject to a complete export ban. China has a largely monopoly on heavy rare earths. In the dispute over an increase in export tariffs for rare earths planned in January 2011, the USA announced in December 2010 that it would, if necessary, sue China before the WTO. This was implemented on March 13, 2012; the EU and Japan participated in the lawsuit. After the WTO declared the export restrictions inadmissible, China lifted the corresponding export quotas. In response to international protests, China founded a rare earth trade association in April 2012. The association will coordinate the mining and processing of raw materials and develop “a reasonable price mechanism”, announced the Ministry of Industry and Information Technology.

With the aforementioned export restrictions, China could aim to secure its own needs and relocate raw material-dependent added value to the domestic market. It is now doubted that this policy is primarily aimed at relocating western production to China, as western companies are increasingly reporting that their plants in China are at a disadvantage compared to domestic companies. Critics see the establishment of the aforementioned Chinese trade association for rare earths as an attempt to control the sector even more closely. The supply of rare earths played a specific role in Chinese foreign policy towards Japan. Following the arrest of the captain of a Chinese fishing trawler who had rammed a Japanese coast guard boat, shipments of rare earths to Japan were blocked until the captain was released and flown to China. Japanese companies are now taking precautionary measures; Sun made Toyota a separate working group which is to ensure the supply of rare earths. The Japanese Ministry of Trade and Economy also took on the problem and tried to get an overview of the situation by means of a company survey.

Because of China's restrictive measures, the mining company Molycorp Minerals wants to resume mining in the USA ( Mountain Pass ), but US companies have been missing production permits in the meantime. After international mining corporations had announced that they would again produce rare earths in various parts of the world and some of the mines that had been closed were reactivated, fears, especially in German industry circles, that the future Chinese export policy would lead to bottlenecks in the supply of rare earths were reduced. In 2018, 20% of German imports came from Russia , and experts did not expect any short-term effects of a trade dispute between the USA and China on the supply in Germany in 2019, even due to long-term supply contracts.

In Kvanefjeld in Greenland (marked as (1)) there is a pilot plant for the mining of rare earths

According to geologists, there are further potential mining areas mainly in Greenland and Canada ; For example, an area in Kvanefjeld in Greenland could yield up to 100,000 tons of rare earths per year, which would come close to China's current total production of 130,000 tons per year. Dismantling in Kvanefjeld began in 2016 with a pilot plant, which was in the assessment phase in 2016/2017.

Market observers such as the Federal Institute for Geosciences and Raw Materials or the German Raw Materials Agency consider different price developments for light and heavy rare earths to be likely. While the price of cerium mixed metal (light rare earths) by mid-2011 fell by a factor of 15 to mid-2014, is expected to remain at earth heavy rare a bottleneck. According to a study by Roland Berger Strategy Consultants from 2011, the prices for heavy rare earths should rise in the near future and remain at a high level in the long term. The prices for light rare earths, however, should fall in the near future, but this depends on the guidelines of Chinese politics.

In early 2015, China lifted its export restrictions. In 2013, 22,493 tonnes were exported, by November 2014 it was around 24,886 tonnes - the export limit of around 31,000 tonnes was far from being exhausted.

In June 2019, the People's Republic of China threatens to curb sales of rare earths to the USA as a result of the trade conflict between the United States and the People's Republic of China .

literature

Specialist literature

Fiction

Web links

Commons : Rare earth elements  - collection of pictures, videos and audio files
 Wikinews: Rare Earths  - In The News

Individual evidence

  1. ↑ Öko Institut eV 2011: Rare earths - data & facts (PDF; 139 kB).
  2. ^ CK Gupta, N. Krishnamurthy: Extactive Metallurgy of Rare Earths. CRC Press, 2005, ISBN 0-415-33340-7 .
  3. ^ Jacob A. Marinsky, Lawrence E. Glendenin, Charles D. Coryell: The Chemical Identification of Radioisotopes of Neodymium and of Element 61 . In: J. Am. Chem. Soc. tape 11 , no. 69 , 1947, pp. 2781-2785 , doi : 10.1021 / ja01203a059 .
  4. ^ A b Kunal Sawhney: Greenland Minerals' Kvanefjeld Project To Be Cornerstone Of Future Rare Earth Supply; Stock Up 13.04%. In: Kalkine Media> Resources> Mining. Kalkine Media Pty Ltd., Sidney, August 9, 2019, accessed on August 21, 2019 .
  5. ↑ Occurrence and production of mineral raw materials - a country comparison. (PDF) Federal Institute for Geosciences and Natural Resources, accessed on October 22, 2015 .
  6. ↑ Rare earths: dispute over China's market power enters a new round. In: heise.de. Retrieved October 22, 2015 .
  7. ↑ a b c Andreas Rostek-Buetti: When rare earths become "weapons" | DW | 06/06/2019. In: Deutsche Welle> Raw materials. Deutsche Welle (www.dw.com), June 6, 2019, accessed on August 22, 2019 .
  8. ↑ Financial Times Deutschland: Precious rarities with a high risk factor ( Memento from October 1, 2009 in the Internet Archive ), accessed on August 4, 2010.
  9. ↑ wallstreet-online.de: South Korea cooperates with Vietnam in the search for rare earths , from December 21, 2010.
  10. ↑ Huge deposits of rare earths discovered. , Die Welt , July 4, 2011, accessed October 19, 2012.
  11. ↑ boerse-express.com: World's largest rare earth deposit found in North Korea ( memento of the original from October 18, 2017 in the Internet Archive ) Info: The archive link was automatically inserted and not yet checked. Please check the original and archive link according to the instructions and then remove this notice. , dated December 7, 2013. @1@ 2Template: Webachiv / IABot / www.boerse-express.com
  12. ↑ Seltenerden Storkwitz AG: Expert opinion confirms estimates of the only known rare earth deposit in Central Europe , accessed on December 4, 2013
  13. ^ Ditmar Wohlgemuth: occurrence near Storkwitz economically unattractive. In: Leipziger Volkszeitung> Delitzsch> rare earths. Leipziger Verlags- und Druckereigesellschaft mbH & Co. KG, January 28, 2017, accessed on August 22, 2019 .
  14. ↑ spiegel.de: Rare earths in Saxony: Search for the treasure of Storkwitz , from January 10, 2012.
  15. ^ Gordon B. Haxel, James B. Hedrick, Greta J. Orris: Rare earth elements - Critical resources for high technology . US Geological Survey, Fact Sheet 087-02, May 17, 2005.
  16. ↑ USGS Minerals Information: Mineral Commodity Summaries, Rare Earths 2012 , accessed on November 23, 2014 (PDF; 30 kB)
  17. ↑ USGS Minerals Information: Mineral Commodity Summaries, Rare Earths 2013 , accessed on November 23, 2014 (PDF; 33 kB)
  18. ↑ USGS Minerals Information: Mineral Commodity Summaries, Rare Earths 2014 , accessed on November 23, 2014 (PDF; 34 kB)
  19. ↑ USGS: Mineral Commodity Summaries, Rare Earths 2015
  20. ↑ USGS: Mineral Commodity Summaries, Rare Earths 2016. Accessed May 13, 2018.
  21. ↑ USGS: Mineral Commodity Summaries, Rare Earths 2017. Retrieved May 13, 2018.
  22. ↑ USGS: Mineral Commodity Summaries, Rare Earths 2018. Retrieved May 13, 2018.
  23. ^ For Australia, Joint Ore Reserves Committee (JORC) -compliant reserves were about 2.2 million tons.
  24. ↑ Is Mining Rare Minerals on the Moon Vital to National Security? lunarscience.arc.nasa.gov, October 4, 2010; accessed November 2, 2010.
  25. ↑ KREEP planeten.ch, accessed on November 2, 2010.
  26. ^ Near Earth Objects as Future Resources neo.jpl.nasa.gov; Asteroid mining en.wikipedia accessed on November 2, 2010.
  27. ↑ Erwin Riedel: Inorganic Chemistry . ISBN 978-3-11-018168-5 ( page 765 in Google book search).
  28. ^ Jacques Lucas, Pierre Lucas, Thierry Le Mercier, Alain Rollat, William G. Davenport: Rare Earths: Science, Technology, Production and Use . Elsevier, 2014, ISBN 0-444-62744-8 ( Google Books ).
  29. ↑ SOLVAY latest developments in Rare Earth Recovery from Urban Mines , November 13, 2015
  30. ↑ https://www.sciencedaily.com/releases/2019/03/190314101302.htm
  31. ↑ https://inl.gov/article/critical-materials-2/
  32. ↑ ORF website: China is sitting on rare treasures ( online ), accessed on August 4, 2010.
  33. ↑ Gisele Azimi, Rajeev Dhiman, Hyuk-Min Kwon, Adam T. Paxson, Kripa K. Varanasi: Hydrophobicity of rare-earth oxide ceramics . In: Nature Materials . tape 12 , no. 4 , 2013, p. 315-320 , doi : 10.1038 / nmat3545 ( libgen.io ).
  34. ↑ M. Simon: Hydrophobic Ceramics ( Memento of the original from December 24, 2015 in the Internet Archive ) Info: The @1@ 2Template: Webachiv / IABot / www.top-solar-info.de archive link was automatically inserted and not yet checked. Please check the original and archive link according to the instructions and then remove this notice. , January 23, 2013.
  35. ↑ why, why, why? : Rare earths - scarce and indispensable, Greenpeace Magazin 2. 2011, page 10
  36. ↑ Berliner Zeitung: Raw material bottleneck - German industry is sounding the alarm . Number 251, October 27, 2010, p. 2.
  37. ↑ Dieter Lohmann, Nadja Podbregar: In focus: Natural resources. Looking for raw materials. Springer, Berlin / Heidelberg 2012, p. 10.
  38. ↑ Maren Liedtke and Harald Elsner: rare earths. (PDF) In: Commodity Top News No. 31. Federal Institute for Geosciences and Natural Resources , accessed on July 14, 2011 .
  39. ↑ Federal Institute for Geosciences and Natural Resources: Current BGR research: China's share of global rare earth production is falling only slowly , March 12, 2014.
  40. ↑ China's Rare Earth Exports Surge in Value. (No longer available online.) January 18, 2011, archived from the original on February 13, 2011 ; accessed on March 6, 2011 (fee required). Info: The archive link was inserted automatically and has not yet been checked. Please check the original and archive link according to the instructions and then remove this notice. @1@ 2Template: Webachiv / IABot / thechinaperspective.com
  41. ↑ Federal Institute for Geosciences and Natural Resources: Current BGR research: China's share of global rare earth production is falling only slowly , March 12, 2014
  42. ↑ Der Spiegel: USA threatens China with a trade war for rare earths , accessed on December 25, 2010.
  43. ↑ faz.net: EU and United States are suing China , March 13, 2012, accessed on March 13, 2012.
  44. ↑ Deutschlandfunk aktuell: [1] , accessed on January 5, 2014.
  45. ↑ a b Spiegel Online: China strengthens control over high-tech metals , April 9, 2012.
  46. ↑ KEITH BRADSHER: China Tightens Grip on Rare Minerals. In: New York Times. August 31, 2009, accessed March 6, 2011 .
  47. ↑ a b China's near monopoly on rare earths. Export embargo as a means of political pressure. In: Neue Zürcher Zeitung, international edition. October 1, 2010.
  48. ↑ China's dispute with Japan over raw materials also has other aspects; For example, both states lay claim to the oil and gas-rich area of ​​the Senkaku Islands .
  49. ^ Lawsuits by Japanese companies. In: Neue Zürcher Zeitung, international edition. October 1, 2010.
  50. ↑ Online edition of the Technology Review , cf. Rare earths: mining company wants to break Chinese monopoly in: Heise Newsticker from November 1st. Carol Raulston, spokeswoman for the American National Mining Association, is quoted there: "If you stop mining, the technical expertise is also lost."
  51. ↑ Karl Geschneidner, rare earth specialist at Ames National Laboratory in Iowa.
  52. ↑ n-tv.de, jaz / dpa: Experts: No bottlenecks in Germany. In: n-tv news> economy. n-tv Nachrichtenfernsehen GmbH, May 30, 2019, accessed on August 22, 2019 .
  53. ↑ Axel Bojanowski : Reduced Chinese exports: German companies are running out of high-tech metals . In: Spiegel Online . October 21, 2010 ( spiegel.de [accessed on August 21, 2019]).
  54. ↑ Federal Institute for Geosciences and Natural Resources: Current BGR research: China's share of global rare earth production is falling only slowly , March 12, 2014
  55. ↑ Metal-Pages.com: Cerium prices
  56. ↑ Thorsten Cmiel: Where to find rare earths , Investment Alternatives, May 31, 2012.
  57. ^ The rare earth challenge: How companies react and what they expect for the future , Study, Roland Berger Strategy Consultants, 2011.
  58. ↑ FAZ.net January 5, 2015: Why China is releasing rare earths
  59. ↑ Handelsblatt.com: China is threatening the USA with throttling exports of rare earths