Neodymium REE Collection rare earth metals elements

Neodymium

Like the twins, Castor and Pollux, from Greek mythology who possessed special powers and strong bonds, so are neodymium and praseodymium, the elemental twins, that were difficult to separate and possess a multitude of special properties.

Applications

  • Wind turbine generators create electricity using neodymium-iron-boron magnets.
  • Neodymium yttrium aluminum garnet (Nd:YAG) are the most widely used lasers in commercial and military applications. It is used for cutting, welding, scribing, boring, ranging, and targeting.
  • Electric motors in hybrid "HEV" and electric vehicles "EV" use high-strength neodymium magnets to power the car.
  • Magnetic Resonance Imaging (MRI's) using NdFeB can be used to obtain an internal view of the body without radiation.

Interesting Facts

  • Neodymium-iron-boron (Nd2Fe14B) high-strength permanent magnets are the strongest in the world.
  • When switched to 'vibrate' mode, a miniature NdFeB magnet causes cell phones to vibrate when a call is received.
  • A thumbnail size, high-strength NdFeB magnet is so strong that when placed on a refrigerator it cannot be removed by hand.
  • High-end audio headphones and speakers use NdFeB magnets to accurately reproduce sound and base across a full spectrum.
  • YAG lasers are used to remove tattoos.

Discovery

Neodymium and praseodymium were discovered at the same time. Many chemists in the world believed didymium was a mixture of elements, but were unable to figure out how to separate them. So finally, when a chemist announced he had accomplished the separation in front of the Vienna Academy of Sciences on June 18, 1885, many were skeptical (Weeks and Leicester, 1968, p. 685). That chemist was Baron Carl Auer von Welsbach, who was studying in Heidelberg under the direction of German chemist Robert Bunsen. Auer von Welsbach noted "Only Bunsen, to whom I first showed the discovery, recognized immediately that a splitting of didymium had actually been accomplished. This acknowledgement from Bunsen, who had, as is known, published very beautiful and comprehensive researches on didymium, showed how unselfishly this great investigator used to judge the researches of younger men" (Feldhaus, 1928). To separate didymium, Auer von Welsbach used multiple fractionations of ammonium didymium nitrate. His discovery resulted in two new elements, which he named neodymium and praseodymium (Auer von Welsbach, 1885 [2 refs.]). The more abundant new earth was neodymium, from the Greek neos didumous, meaning new twin (Hedrick, unpublished).

Definition

Neodymium is a silvery-white metal that is moderately reactive and quickly oxidizes to a yellowish color in air. The metal is soft and ductile. It has a hexagonal structure, a density of 7.004 gm/cm3, a melting point of 1021 °C, and a boiling point of 3027 °C. Neodymium oxide, or neodymia, occurs as a sesquioxide with the formula Nd2O3. The oxide is a pale white powder with a specific gravity of 7.3 gm/cm3, a melting point of 2233 °C, and a formula weight of 336.48.

Preparation of Metal

Neodymium metal is typically prepared by calciothermic reduction of the trihalide, typically transparent violet colored crystals of NdF3, in a Ta crucible. Neodymium metal has a low melting point and high boiling point, similar to La, Ce, and Pr. To prepare the NdF3, a mixture of anhydrous hydrofluoric acid and 60% argon is streamed over Nd2O3 at 700 °C for 16 hours in a platinum-lined Inconel furnace tube. This produces a neodymium fluoride with approximately 300 ppm oxygen as an impurity. In a second purification step the oxygen content is lowered to less than 20 ppm by heating the fluoride to about 50 °C above its melting point in a platinum crucible within a graphite cell. The NdF3 is placed in a Ta crucible, reduced with a 15% excess of the theoretical amount of calcium metal required, and heated in an induction vacuum furnace under an inert Ar atmosphere to a temperature above the highest melting reductant or product (Beaudry and Gschneidner, Jr., 1978). The Ca metal combines with the F to form CaF2 and the remaining product is a high-purity neodymium metal.

Source

Large resources of neodymium are contained in LREE-enriched minerals. Neodymium occurs in the Earth's crust at an average concentration of 28 parts per million. The primary source of neodymium is from carbonatites and the LREE-mineral bastnäsite. Bastnäsite deposits in China and the United States constitute the largest percentage of the world's rare-earth economic resources. Neodymium is also a major constituent in the LREE-mineral monazite which constitutes the second largest segment of rare-earth resources. Monazite deposits are located in Australia, Brazil, China, India, Malaysia, South Africa, Sri Lanka, Thailand, and the United States in paleoplacer and recent placer deposits, sedimentary deposits, veins, pegmatites, carbonatites, and alkaline complexes (Hedrick, 2010). Neodymium sourced from the LREE-mineral loparite is recovered from a large alkali igneous intrusion in Russia (Hedrick, Sinha, and Kosynkin, 1997).

Mining

Neodymium is mined from a variety of ore minerals and deposits using various methods. Bastnäsite is mined in the United States as a primary product from a hard-rock carbonatite. The deposit is mined via bench-cut open pit methods. Ore is drilled and blasted, loaded into trucks by loaders, and hauled to the mill. At the mill the blasted ore is crushed, screened, and processed by flotation to produce a bastnäsite concentrate. In China, bastnäsite and lesser amounts of associated monazite are also mined from a carbonatite. The ore is recovered as a byproduct of iron ore mining by hard-rock open pit methods. After crushing the ore is separated from the iron ore by flotation to produce a bastnäsite concentrate and a bastnäsite-monazite concentrate (Hedrick, 1990).

Monazite is recovered from heavy-mineral sands (specific gravity >2.9) deposits in various parts of the world as a byproduct of mining zircon and titanium-minerals or tin minerals. Heavy mineral sands are recovered by surface placer methods from unconsolidated sands. Many of these deposits are mined using floating dredges which separate the heavy-mineral sands from the lighter weight fraction with an on-board wet mill through a series of wet-gravity equipment that includes screens, hydrocyclones, spirals, and cone concentrators. Consolidated or partially consolidated sand deposits that are too difficult to mine by dredging are mined by dry methods. Ore is stripped by typical earth-moving equipment with bulldozers, scrapers, and loaders or by water jet methods. Ore recovered by these methods is crushed and screened and then processed by the wet mill described above. Wet mill heavy-mineral concentrate is sent to a dry mill for processing to separate the individual heavy-minerals using a combination of scrubbing, drying, screening, electrostatic, electromagnetic, magnetic, and gravity processes. Vein monazite has been mined by hard-rock methods in South Africa and the United States (Hedrick, 2010). Loparite is mined by underground methods using room and pillar methods. Ore is drilled and blasted and removed from the mine. The ore is then processed by the same hard-rock methods as applied to bastnäsite to make a loparite concentrate.

Selected neodymium minerals

Bastnäsite-(Ce) (Ce,La,Nd,Pr)(CO3)F
Bastnäsite-(Nd) (Nd,Ce,La,Pr)(CO3)F
Monazite-(Ce) (Ce,La,Nd,Th)(PO4)
Monazite-(Nd) (Nd,Ce,La,Th)(PO4)
Loparite-(Ce) (Ce,Na,Ca,Sr,Th)(Ti,Nb,Ta,Fe+3)O3
Aeschenite-(Nd) (Nd,Ce,Ca)(Ti,Nb)2(O,OH)6
Åskagenite-(Nd) (Mn2+,Nd)(Al2,Fe3+)(Si2O7)(SiO4)O2
Allanite-(Ce) (Ca,Ce)(Al2,Fe+2)(Si2O7)(SiO4)O(OH)
Fergusonite-(Nd) (Nd,Ce)(Nb,Ti)O4
Florencite-(Nd) (Nd,La,Ce)Al3(PO4)2(OH)6
Lanthanite-(Nd) (Nd,La)2(CO3)3 • 8 H2O
Parisite-(Ce) Ca(Ce,La)2(CO3)3F2
Parisite-(Nd) Ca(Nd,Ce,La)2(CO3)3F2
Synchysite-(Nd) Ca(Nd,Y,Gd)(CO3)2F
Mckelveyite-(Nd) (Ba,Sr)(Nd,Ce,La)(CO3)2 • 4-10 H2O
Rhabdophane-(Nd) (Nd,Ce,La)(PO4) • H2O

References

Andres, Klaus, and Paul H. Schmidt, 1977, PrNi5 as a cryogenic refrigerant (filed October 20, 1975): United States Patent 4028905, June 14, 5 p.

Auer von Welsbach, Carl, 1885, Die Zerlegung des Didymus in seine Elemente [The Separation of Didymium into its Elements], Chemische Berichte, part 3, v. 18, p. 605.

Auer von Welsbach, Carl, 1885, Die Zerlegung des Didymus in seine Elemente [The Separation of Didymium into its Elements], Monatshefte fuer Chemie, v. 6, p. 477-491.

Beaudry and Bernard J. and Karl A. Gschneidner, Jr., 1978, Preparation and Basic Properties of the Rare Earth Metals: chapter 2 in Handbook on the Physics and Chemistry of Rare Earths-Volume 1:Metals, (Gschneidner, Jr. and Eyring, editors), North-Holland, New York, p. 173-232.

Eyring, LeRoy, 1979, The binary rare earth oxides: chapter 27 in Handbook on the Physics and Chemistry of Rare Earths-Volume 3:Non-Metallic Comounds I, (Gschneidner, Jr. and Eyring, editors), North-Holland, New York, p. 337-399.

Feldhaus, 1928, Zum 70 - Geburtstage von Auer von Welsbach [To 70 - Birthday of Auer von Welsbach]: Chemiker-Zeitung, September 1, v. 52, p. 22-23.

Ferro, Sergio, 2011, Physicochemical and Electrical Properties of Praseodymium Oxides: International Journal of Electrochemistry - Volume 2011, Hindawi Publishing Co., open access journal, 7 p.

Hedrick, James B., Rare earth history: unpublished manuscript, 11 p.

FHedrick, James B., 2010, Rare earths: chapter in Mineral commodity summaries 2010, U.S. Geological Survey, p. 128-129.

Hedrick, James B., 1990, Rare earths - The lanthanides, yttrium, and scandium: chapter in Minerals Yearbook 1990, U.S. Geological Survey, v. 1, p. 903-922.

Hedrick, James B., 1991, Rare earths - The lanthanides, yttrium, and scandium: chapter in Minerals Yearbook 1991, U.S. Geological Survey, v. 1, p. 1211-1237.

Weeks, Mary E., and Henry M. Leicester, 1968, Discovery of the Elements (7th ed.): Easton, Pennsylvania, Journal of Chemical Education, 896 p.

Electrons per shell:
2, 8, 18, 22, 8, 2
Atomic number,
Protons, Electrons:
60
Number of Neutrons:
84
Atomic Mass:
144.24 amu
Melting Point:
1021 °C
Boiling Point:
3027 °C
Density @ 293 K:
7.004 g/cm3
Crystal structure:
hexagonal
Color:
silvery