Thursday, December 10, 2009

Rare Earths

Rare earth elements are incorporated into 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 (primarily batteries and magnets).[5]
Rare earth ions are used as the active ions in luminescent materials used in optoelectronics
applications, most notably the Nd:YAG
laser. Erbium-doped fiber amplifiers are significant devices in optical-fiber communication systems. Phosphors
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.

Global rare earth production

Global production 1950-2000

Until 1948, most of the world's rare earths were sourced from placer

sand deposits in India
Through the 1950s, South Africa took the status as the world's rare earth source, after large rare earth bearing veins were discovered in Monazite
Today, those 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 95% of the world's rare earth supply.[5]

The use of rare earth elements in modern technology has increased dramatically over the past years. For example,dysprosium

has gained significant importance for its use in the construction of hybrid car
Unfortunately, this new demand has strained supply, and there is growing concern that the world may soon face a shortage of the materials.[8]
In several years, worldwide demand for rare earth elements is expected to exceed supply by 40,000 tonnes annually unless major new sources are developed.[9]
All of the world's heavy rare earths (such as dysprosium) are sourced from Chinese rare earth sources such as the polymetallic
Bayan Obo
Illegal rare earth mines are common in rural China and are often known to release toxic wastes into the general water supply.[11]
A rare earth element mine in California
is set to reopen by 2012. A site at Thor Lake in the Northwest Territories
is also under development. Locations in Vietnam
have also been considered.[9]

Chinese export quotas have also resulted in a dramatic shift in the world's rare earth knowledge base. For example, the division of General Motors which deals with miniaturized magnet research shut down its US office and moved all of its staff to China

in 2006.[12]

On Sept. 1, 2009, China announced plans to reduce its quota to 35,000 tons per year in 2010-2015, supposedly to conserve scarce resources and protect the environment.[13]

Other sources of rare earth has been searched to avoid shortages and China's monopoly, mainly in South Africa
, Brazil
and the United States

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