Uses of Rare Earths Part One: Light Rare Earths

Rare earth elements have wide commercial applications. The light rare earths – lanthanum, cerium, praseodymium and neodymium – are the focus of this article.

Lanthanum
Lanthanum gets its name from the Greek word lanthanein, which means "to escape notice." It was discovered in 1839 when it was extracted from impure cerium nitrate. In 1929, it was isolated in its pure form. Lanthanum is found in rare-earth minerals, principally in the ores monazite and bastnasite. Misch metal, which is used in making lighter flint, also contains lanthanum. Compounds containing lanthanum are used in carbon lighting, particularly in motion picture studio lighting and projection. Certain compounds are used to make special glass, often optical glass. An addition of lanthanum can help create nodular cast iron as well.

In modern commercial applications, lanthanum is prevalent. Toyota's Prius hybrid car contains approximately 10 pounds of lanthanum overall, for example. Nickel-lanthanum batteries are a very efficient alternative to traditional car batteries. Hybrid car batteries and batteries for small Chinese mopeds both use lanthanum, and there is not enough of the mineral to meet current demand. As hybrid cars become more common, the demand for lanthanum will increase even more. The market for lanthanum is thriving, and it is currently possible to create it in a lab by reducing the anhydrous fluoride with calcium.

Cerium
Cerium, the most abundant of the rare-earth minerals, was discovered in 1803 and named after the asteroid Ceres. Four isotopes of cerium occur in nature. Cerium is found in several minerals, including allanite, monazite and cerite. Deposits of cerium itself have been found in Brazil, India and southern California. Like lanthanum, cerium is used extensively in the film industry for carbon lighting. It, too, is in compounds that can create nodular cast iron. It also has applications in the manufacture and treatment of glass, as well as cigarette lighters and self-cleaning ovens.

Cerium is added to glass to color it and increase its absorption of ultraviolet light. This application is important in building, as windows that do not allow much ultraviolet light to enter are valuable objects. It also colors enamels. Added to steel or iron, it increases the metals' strength. Cerium is a component in fluorescent lighting and can polish glass. Its many uses create a fairly high demand for cerium, which the market can meet due to the mineral's relative abundance in the world.

Praseodymium
Praseodymium, discovered in 1885, derives its name from Greek words meaning "green twin." It is found in monazite and bastnanite only. These ores are mined in China, Brazil, the U.S., India, Sri Lanka and Australia. Worldwide, 2,500 metric tons of praseodymium are produced annually, and the reserves of the mineral are approximately 2 million tons. Like cerium, praseodymium can be used in the production of glass. It gives glass a yellow tint, and filters out ultraviolet radiation. Praseodymium is involved in making glass for goggles that protect the eyes of welders.

Praseodymium alloyed with magnesium produces a very strong metal that is used in the engines of aircraft. It also shows up in more humble products, such as color televisions, fluorescent lights and energy-saving light bulbs. There are many applications of praseodymium in ceramics as well, as it lends a highly prized yellow tint to the material. Its optical properties have the potential to be applied in the telecommunications industry as well as for decorative purposes. Praseodymium, which is mildly toxic, often ends up in the water supply as a byproduct of industrial processes. It has a negative impact on the health of aquatic animals.

Neodymium
Neodymium, named for the Greek words meaning "new twin," was also discovered in 1885. It is a common mineral, about twice as common as lead and half as common as copper. Neodymium is found in monazite and bastnasite ores, and is also a byproduct of nuclear fission. Like praseodymium, neodymium lends color to glass and ceramics, ranging in hue from grey to violet. It is also used to create the goggles welders and glass-blowers wear to protect their eyes. One of the most prevalent uses of neodymium is as part of a compound that creates a very strong magnet. Neodymium magnets are used in computers, magnetic resonance instruments (MRIs), maglev trains, magnetic separators and even cathode-ray televisions.

Another major use for neodymium magnets is in wind turbines. As the alternative energy industry grows, the demand for neodymium and other rare-earth elements used to create strong, permanent magnets is expected to skyrocket. Direct-drive wind turbines, which use neodymium magnets, can operate at lower wind speeds than traditional turbines, allowing wind farms to create more electricity and turn a greater profit. Rare earth mineral prices may even influence the adoption of wind-generated electricity.