Rare Earths

21st Century Strategic Metals
Rare earths possess certain chemical and physical properties which make them indispensable in many high-tech applications. They are widely recognized as being among the most valuable and strategically important minerals for the continued development of a modern technological society. Among the key properties of rare earths are their high thermal and electrical conductivity, magnetism, luminosity, catalytic and optical properties.

Demand for rare earths is estimated to have grown at approximately 12% per annum in the last part of the decade. This growth has principally been driven by the ever-increasing range of applications utilizing rare earths across consumer electronics, clean energy technologies, high-tech and defense applications as traditional materials reach their operational performance limits.

Rare Earths
Rare Earths are not in fact rare. Four of these elements (Cerium, Lanthanum, Neodymium, and Yttrium) occur in more abundance in the earths crust than Lead, and are many times more abundant than Silver. The term “rare” has more to do with the rarity of economic concentrations of the minerals from which they are extracted and the difficulty in separating the elements from one another due to their remarkably similar properties.

China’s Dominance of the Rare Earths Industry
Until the 1960s global production of rare earths totalled less than 10,000 metric tons per year, with India, Brazil and South Africa as the major producers. Through the 1960s until the 1980s, the Mountain Pass rare earth mine in California was the leading producer. Today, the Indian and South African deposits still produce some rare earth concentrates, but they are dwarfed by the scale of Chinese production.

China now produces over 97% of the world’s rare earth supply, mostly in Inner Mongolia, even though it has only 37% of proven reserves. More specifically, the vast majorty of Chinese reserves can be found within the massive polymetallic deposit at Bayan Obo in Inner Mongolia.

Elements – Applications of the rare earth elements

Lanthanum
Lanthanum is a key component in batteries for hybrid vehicles, computers, and electronic devices.  Its physical and chemical properties enable the elements used in a variety of other products.  Lanthanum is utilized in hydrogen fuel storage cells, special optical glasses, electronic vacuums, carbon lighting applications, as doping agents in camera and telescope lenses, and in polishing glass and gemstones.  It also has major applications in petroleum cracking, and as an alloy for many different metals.
Cerium
Cerium oxide is widely used to polish glass surfaces.  Other Cerium compounds are used to manufacture glass and enamels both as ingredients, as well as colour removal agents. Cerium is a component in solar panels, LEDs, catalytic converters, thermal resistance alloys, carbon arc lighting, self-cleaning ovens, petroleum refining, hardening agents, and dental ceramics.
Praseodymium
Praseodymium is most widely used as an alloying agent with magnesium for high-strength metal applications in aircraft engines. It is also used in super magnets, catalytic converters, UV protective glasses, carbon arc lights, and CAT scan scintillators. The element is additionally used as a doping agent in fibre optic cables, and in several metal alloys.
Neodymium
Neodymium is essential in the production of the world’s strongest super magnets, which are present in hybrid cars, state-of-the-art wind and tidal turbines, industrial motors, air conditioners, elevators, microphones, loudspeakers, computer hard drives, in-ear headphones, and guitar pick-ups. When combined with Terbium, or Dysprosium, a Neodymium magnet can withstand the highest temperatures of any magnet, allowing the element to be used in electric cars. Neodymium has many additional uses. It is utilized in incandescent light bulbs, cathode ray tubes, as a glass filter and colorant, as a doping agent in Yttrium-Aluminum-Garnet lasers, and for glare-reduction in rear-view mirrors.
Promethium
Promethium was the last of the rare-earths family elements to be discovered. In 1902 the Czech chemist Bohuslav Brauner (1855-1935) improved Mendeleyev’s period chart by extending it downward after Lanthanum. He predicted the existence of an element in between Neodymium and Samarium.
Samarium
The major commercial application of samarium is in samarium-cobalt magnets which have permanent magnetization second only to neodymium magnets; however, samarium compounds can withstand significantly higher temperatures, above 700 °C, without losing their magnetic properties. Radioactive isotope samarium-153 is the major component of the drug samarium (153Sm) lexidronam (Quadramet) which kills cancer cells in the treatment of lung cancer, prostate cancer, breast cancer and osteosarcoma.
Europium
Europium is the most reactive of the rare earth elements. It rapidly oxidizes in air: bulk oxidation of a centimeter-sized sample occurs within several days. It resembles calcium in its reaction with water.
Gadolinium
When added to iron, chromium, or related alloys, gadolinium greatly improves the workability and raises resistance to high temperature oxidization. It is also utilized in microwave applications, CDs, computer memory devices, MRI image enhancing, neutron radiography, and for making phosphors in TV tubes. One final use of Gadolinium comes in nuclear reactors as an emergency shut-down mechanism.
Terbium
Terbium is used in colour TV tubes and fluorescent lamps as a green phosphor. In combination with Europium blue and red phosphors, the three create trichromatic fluorescent lighting, which is much brighter than conventional fluorescent lighting. Another green application for Terbium can be found in combination with neodymium for production of the world’s most heat resistant super magnets. The element is also used in alloys, crystal stabilizers in fuel cells that operate at high temperatures, specialty lasers, and to dope calcium fluoride, sodium borate and strontium molybdate materials. Terbium is a component of Terfenol-D, a material that is used in transducers, high-precision liquid fuel injectors and in a new form of audio equipment that has the potential to revolutionize the speaker industry.
Dysprosium
Dysprosium’s thermal neutron absorption cross-section and high melting point enable it to be used in nuclear control applications. The element can be added to Neodymium-iron-boron magnets to raise the strength and corrosion resistance of applications like drive motors for hybrid electric vehicles. Like Terbium, Dysprosium is a component of Terfenol-D; a very promising material for future technology applications. It is also used in CDs, chemical reaction testing, laser materials, and dosimeters.
Holmium
Holmium has one of the highest known magnetic moments. The element is imperative in the creation of the strongest, artificially generated magnetic fields. Holmium is also used in nuclear control rods, solid-state lasers in eye-safe medical and dental microwave equipment, and as a yellow and red glass, and cubic zirconia colorant.
Erbium
Erbium is used in neutron-absorbing control rods, creating lasers for cutting and welding, and as a doping agent for optical fibers. As an alloy additive, Erbium lowers the hardness and improves the workability of numerous metals. In oxide form, the element is used as a pink colorant in glass and porcelain enamel glazes, and it is often used in photographic filters.
Thulium
Thulium is the 2nd rarest of REEs, only next to Promethium, which does not occur naturally in the earth’s crust. Because of its scarcity and high price, there are few widely-used Thulium applications. Its current uses are mainly scientific experimentation, and in portable x-ray devices use for areas where electric power is not available.
Ytterbium
Ytterbium is used some in solar cells, optical glasses, crystals, and ceramics. It can be utilized as a doping material for high power solid-state lasers and as an alloy that helps to strengthen stainless steel. Like Thulium, Ytterbium is employed in portable x-ray machines where electricity is not available.
Lutetium
Lutetium is mainly used as a catalyst in refining petroleum, hydrogenation and polymerization processes, and in organic LEDs. Lutetium is currently being investigated as an agent for possible cancer treatments. It is also used in x-ray phosphors and computer memory devices.