Rare-Earth Elements
Rare-earth elements (REEs) consist of a group of 17 chemical elements in the periodic table known as the lanthanides, along with scandium and yttrium. These elements are crucial for a variety of high-tech and industrial applications due to their unique physical and chemical properties.
Characteristics and Classification
The lanthanides include the elements with atomic numbers 57 through 71, from lanthanum to lutetium. Scandium and yttrium are grouped with the lanthanides because they are found in the same ore deposits and exhibit similar chemical properties. Notably, all isotopes of promethium are radioactive and do not naturally occur in the Earth's crust, except in trace amounts produced by the spontaneous fission of uranium-238.
The term "rare-earth" is somewhat misleading. These elements are relatively abundant in the Earth's crust, with cerium being more prevalent than copper. However, they are rarely found in concentrations that make them economically viable to extract, often dispersed as trace impurities within other minerals.
Extraction and Production
Extracting rare-earth elements is complex due to the difficulty of isolating them in pure forms. They are not typically found in metallic states but as part of complex compounds. The extraction process involves mining large amounts of ore and requires extensive refinement to achieve usable purity.
The largest producer of rare-earth elements is China, which has significant control over the global supply chain. The Mountain Pass Rare Earth Mine in California is one of the few significant sources outside Asia.
Applications
Rare-earth elements are indispensable in numerous applications due to their magnetic, luminescent, and electrochemical properties. They are vital components in the manufacturing of permanent magnets, catalysts, glass, polishing compounds, and phosphors for cathode ray tubes, as well as in light-emitting diodes and fluorescent lamps.
In the realm of technology, rare-earth elements are crucial in the production of smartphones, electric vehicles, and renewable energy technologies such as wind turbines. Neodymium and samarium are particularly important for creating high-strength magnets used in electric motors.
Economic and Strategic Importance
Given their critical role in modern technology, rare-earth elements are considered strategically important. They are classified as critical minerals by many nations, with efforts underway to diversify sources and reduce dependency on any single producer.