What are rare earth elements and how are they used in modern technologies.green technologies, batteries, cerium, dysprosium, erbium, europium, gadolinium, holmium, lanthanum, lutetium, neodymium, praseodymium, samarium, scandium, terbium, thorium, thulium, ytterbium, and yttrium
You may have been hearing more about rare earth elements (REE) in the news lately as they are becoming more popular as an investment due to their use in green energy products. The principal economic sources of rare earths are the minerals bastnasite, monazite, and loparite and the lateritic ion-adsorption clays. The rare earths, as they are commonly referred to, are a relatively abundant group of 17 elements composed of scandium, yttrium, and the lanthanides. Cerium is the 25th most abundant element of the 78 common elements in the Earth's crust at 60 parts per million, and thulium and lutetium, the least abundant rare-earth elements at about 0.5 part per million. Rare earths are iron gray to silvery metals that are typically soft, malleable, and ductile and usually reactive, especially at elevated temperatures or when finely divided.
The list of rare earth elements are cerium, dysprosium, erbium, europium, gadolinium, holmium, lanthanum, lutetium, neodymium, praseodymium, samarium, scandium, terbium, thorium, thulium, ytterbium, and yttrium.
In 2008, world rare-earth production was primarily from the mineral bastnasite. Rare earths were not mined in the United States in 2008, although there are 3 mines located in the U.S. that are not open due to environmental restrictions. Rare-earth ores were primarily mined by China, with smaller amounts mined in India, Brazil, and Russia and Australia which has recently begun mining rare earths.
China, which produces about 97 percent of the global supply of the vital metals, slashed its export quota by 35 percent for the first half of 2011 compared with a year earlier, saying it wanted to conserve reserves and protect the environment.
Worldwide, about 35% of rare-earth elements are used as catalysts, mainly in the refining of crude oil. Rare-earth elements are also included in catalytic converters of automobiles which increase the oxidation of pollutants.
Approximately 30% of the rare-earth elements are used in the glass and ceramics industry as glass-polishing compounds, decolorizing agents, UV absorbers and anti browning agents, glass and ceramic coloring agents, and in optical lenses and glasses.
About 30% are used in metallurgy as an alloying agent to remove sulfur from steels, as an agent in ductile iron, and as alloying agents to improve the properties of super alloys and alloys of magnesium, aluminum and titanium. A rapidly expanding application is in batteries. Mischmetal (a mixture of rare-earth elements) is a component of nickel metal hydride batteries, which are replacing nickel cadmium batteries in powering portable electronic equipment such as lap top computers and mobile phones.
New application for rare-earth elements is in the production of permanent magnets. Samarium-cobalt permanent magnets are used in industrial, military and aerospace applications. Less costly neodymium-iron-boron magnets are used in automobile starting and accessory motors, medical magnetic-resonance-imaging devices, industrial motors, compact disc players, computer disk drives, personal stereos, and camera motors.
Cerium - Glass polishing, petroleum-cracking catalysts, radiation shielding, alloys with iron for lighter sparking flints, alloys with aluminum, magnesium and steel for improving heat and strength properties.
Dysprosium - Control rods for nuclear reactors, alloyed with neodymium for permanent magnets, catalysts.
Erbium - In ceramics to produce a pink glaze, infra-red absorbing glasses.
Europium - Control rods for nuclear reactors, colored lamps, cathode-ray tubes, red phosphor in color-television tubes, used in lasers and to absorb neutrons.
Gadolinium - Solid-state lasers, computer memory chips, high-temperature refractories, cryogenic refrigerants, used in improving high-temperature characteristics of iron, chromium, and related alloys.
Holmium - Control rods for nuclear reactors, catalysts, refractories.
Lanthanum - Ceramic glazes, high-quality optical glass, camera lenses, microwave crystals, ceramic capacitors, glass polishing, petroleum cracking and movie- and television-studio lighting
Lutetium - De-oxidizer in stainless-steel production, rechargeable batteries, medical uses, red phosphors for color television, superconductors, used in nuclear technology.
Neodymium - Ceramic capacitors, glazes and colored glass, lasers, high-strength permanent magnets, petroleum-cracking catalysts.
Praseodymium - Yellow ceramic pigments, tiles, ceramic capacitors, with neodymium for goggles to shield glass makers against sodium glare, permanent magnets, cryogenic refrigerant.
Samarium - In highly magnetic alloys for permanent magnets, nuclear-reactor controls and neutron shielding, laser, infrared-absorbing glass, and as a neutron absorber in certain nuclear reactors.
Scandium - X-ray tubes, catalysts for polymerization, in hardened nickel-chromium super alloys, dental porcelain, used as a tracer in studies of oil wells and pipelines.
Terbium - Cathode-ray tubes for x-ray and color-television tubes, magnets, optical computer memories, computer hard-drive components; magnetostrictive alloys. Magnetostrictive materials are broadly defined as materials that undergo a change in shape due to change in the magnetization state of the material.
Thorium - Gas mantles, magnesium alloys, and can be used as nuclear fuel in place of uranium.
Thulium - X-ray equipment for small portable medical x-ray units.
Ytterbium - X-ray equipment for portable irradiation devices, lasers and in some special alloys.
Yttrium - De-oxidizer in stainless-steel production, strengthener in magnesium and aluminum alloys, rechargeable batteries, medical uses, and red phosphors for color television, superconductors, and various other metallurgical applications.
The Future of Rare Earth Elements
The US has the second-largest concentrated rare earth deposit after China. Of late, reports that China’s monopoly on the supply of the all-crucial REE required in defense and consumer needs, could prove to be detrimental to the rest of the world. The US lawmakers will look at Chinese monopoly among other issues like re-starting some mines in the US and the western world.
Mining rare earths in China
In Washington, Congress is fretting about the United States military’s dependence on Chinese rare earths, and has just ordered a study of potential alternatives.
It is ironic that the growth of the clean “green” industries requires the input from rare earth elements that are often removed by very destructive and polluting methods. Miners scrape off the topsoil and shovel golden-flecked clay into dirt pits, using acids to extract the rare earths. The acids ultimately wash into streams and rivers, destroying rice paddies and fish farms and tainting water supplies.