Rare Earth Elements
Rare earth elements or rare earth metals are a set of seventeen chemical elements in the periodic table, specifically the fifteen lanthanides plus scandium and yttrium.
Are they really Rare?
Despite their name, rare earth elements (with the exception of the radioactive promethium) are relatively plentiful in the Earth’s crust. However, because of their geochemical properties, rare earth elements are typically dispersed and not often found concentrated in economically exploitable ore deposits. It was the very scarcity of these minerals (previously called “earths”) that led to the term “rare earth”.
The REE’s are grouped together as they display similar chemical properties, in particular the ability to readily discharge and accept electrons, making them indispensable and non-replaceable in many electronic, optical, magnetic and catalytic applications.
Rare Earth Ore
Rare earth elements (REE) do not occur as free metals in the earth’s crust, such that all naturally occurring minerals consist of mixtures of various REE and non-metals.
Bastnaesite, monazite and xenotime are the three most economically significant minerals of the more than 200 minerals known to contain essential or significant REE. Bastnaesite and monazite are principal sources of the light REE’s which account for about 95% of the REE currently utilised. Monazite is also the principal ore of thorium, containing up to 30% Th, which together with smaller quantities of U imparts radioactive properties.
Xenotime and minerals such as allanite are common sources of the heavy REE and yttrium.
Applications of Rare Earths
- Rare earth elements are used in many modern technological devices, including superconductors, samarium-cobalt and neodymium-iron-boron high-flux rare-earth magnets, electronic polishers, refining catalysts and hybrid car components.
- Phosphorus with rare earth dopants are also widely used in cathode ray tube technology such as television sets. The earliest color television CRTs had a poor-quality red; europium as a phosphor dopant made good red phosphors possible.
- Yttrium iron garnet (YIG) spheres have been useful as tunable microwave resonators.
- Rare earth oxides are mixed with Tungsten to improve its high temperature properties for welding, replacing thorium which was mildly hazardous to work with.
- Many of these are essential ingredients in mobile phones, video game machines, computers, Magnetic Resonance Imaging (MRI) equipments and green technologies. Tiny amounts of rare earths dysprosium or terbium might soon be used in electric cars as these let batteries work at high temperatures.
Global Production of Rare Earths
Significant amounts of rare earth elements are produced in only a few countries. China is the dominant producer of rare earth elements and is believed to be responsible for over 97% of the world mine production on a rare earth oxide equivalent basis. Other countries with notable production in 2009 were: India, Brazil, Kyrgyzstan and Malaysia. Minor production may have occurred in Indonesia, Commonwealth of Independent States, Nigeria, North Korea and Vietnam.
China became the world’s dominant producer of rare earth elements in the early 1990s, when production at the Mountain Pass mine in California began to decline. China’s dominance increased rapidly and in 2000 China accounted for about 90% of world rare earth production.
China sold rare earths at such low prices that the others throughout the world were unable to compete. In early 2010 China accounted for over 95% of the world’s rare earth production.
China is also the dominant consumer of rare earth elements, used mainly in manufacturing electronics products for domestic and export markets. Japan and the United States are the second and third largest consumers of rare earth materials. In 2010 China announced that they would significantly restrict their rare earth exports to ensure a supply for domestic manufacturing. This announcement triggered some panic buying and rare earth prices shot up to record high levels.
Chinese companies have also been seeking rare earth properties in other countries. For example: in 2009 China Non-Ferrous Metal Mining Company bought a majority stake in Lynas Corporation, an Australian company that has one of the highest outputs of rare earth elements outside of China.