The rare-earth elements are defined as a group of chemical elements composed of scandium, yttrium, and the lanthanides. The lanthanides are a group of 15 chemically similar elements with atomic numbers 57 through 71, inclusive. Although not a lanthanide, yttrium, atomic number 39, is included in the rare earths because it often occurs with them in nature, having similar chemical properties. Scandium, atomic number 21, is also included in the group, although it typically occurs in rare- earths ores only in minor amounts because of its smaller atomic and ionic size.
Rare-earths production is derived from the rare-earths ores bastnasite, monazite, xenontime, and ion-adsorption clay. Bastnasite is the world's principal source of rare earths and is produced in China and the United States. Significant quantities of rare earths are also recovered from the mineral monazite. Xenotime and ion-adsorption clays account for a much smaller part of the total production but are important sources of yttrium and other heavy-group rare earths.
In 1990, rare earths were produced by at least 14 countries. The United States was the largest rare-earths-producing country, followed by China, Australia, India, and Malaysia. Except for one primary mine in the United States, essentially all rare earths are produced as byproduct during processing for titanium and zirconium minerals, iron minerals, or the tin mineral cassiterite.
Domestic mine production of bastnasite during the 1970's and 1980's showed an overall increase. Most companies increased their ore and separated product capacities during the period to meet growing demand. Price increases during the two decades were tied primarily to adjustments for inflation and increased operating costs. In the 1980's, demand shifted away from mixed rare-earths products, such as mischmetal and mixed compounds, to higher value individual high-purity products. Consumption and production of rare earths decreased significantly in 1985 because of decreased demand for rare-earths-containing petroleum cracking catalysts. The rare-earths industry rebounded during the next 5 years as a result of stable demand in traditional markets and strong demand in new applications.
Principal uses for the rare earths are in petroleum fluid cracking catalysts; metallurgical applications; glass polishing compounds; glass additives; permanent magnets; catalytic converter materials; and television, lighting, and X-ray intensifying phosphors.
- Table 1.--U.S. rare-earth mine production
- Table 2.--Yearend rare-earth concentrate prices
- Table 3.--U.S. imports for consumption of rare-earths
- Table 4.--U.S. exports of rare-earths
- Table 5.--Monazite concentrate: world production, by country
- Table 6.--Apparent consumption of rare-earths by processors in the United States