Views: 11 Author: Site Editor Publish Time: 2017-10-19 Origin: Site
Rare earths are a set of elements known as lanthanides found at the bottom of the periodic table, whose unique properties make them essential to many electronic, optical, magnetic and catalytic applications. The rare earths consist of yttrium and the 15 lanthanide elements (lanthanum, cerium, praseodymium, neodymium, promethium, samarium, europium, gadolinium, terbium, dysprosium, holmium, erbium, thulium, ytterbium, and lutetium). Scandium is found in most rare earth element deposits and is therefore usually classified as a rare earth element.
Despite their name, unlike most commercially mined base and precious metals, most are abundant in nature but are rarely concentrated into mineable ore deposits. The estimated average concentration of the rare earth elements in the Earth’s crust, which ranges from around 150 to 220 parts per million, exceeds that of many other metals that are mined on an industrial scale, such as copper (55 parts per million) and zinc (70 parts per million).
Unlike metal sulfides, which are chemically simple compounds, rare earth element-bearing minerals are quite complex. The rare earth elements have many similar properties and are often found together in geologic deposits. In fact, rare earth elements−bearing minerals, once separated, contain as many as 14 individual rare earth elements (lanthanides and yttrium) that must be further separated and refined. As such, rare earth elements, are typically extracted and refined through dozens of chemical processes to separate the different rare earth elements and remove impurities.