Rare Earth Elements Separation and Purification
Rare earth elements are a group of 17 chemical elements found in the periodic table whose unique properties make them essential for technologies ranging from renewable energy to healthcare applications. With ever increasing demand for the elements, developing sustainable and efficient methods for the separation and purification of rare earths from ore sources is an important process.
The main sources of rare earth element extraction are monazite and bastnaesite ore, which contain the elements in their chemical compounds. These compounds are composed of rare earths and non-rare earth elements, and are typically separated through physical processes such as grinding and sieving. The extracted elements are then further purified by means of a chemical separation process.
The primary method of separating rare earth elements from ore is froth flotation, during which a slurry of ore is introduced to an aerated water medium and an agent which causes the rare earth elements to settle out. This process is used on a wide variety of ores mined from different countries around the world.
A further step in the separation and purification of rare earths is magnetic separation. This is a process in which rare earths become trapped in a magnetic field. The force of the magnet keeps the elements trapped, allowing for easy extraction. This method is most commonly used for the separation of light rare earth elements from ore.
Once separated from the ore, purification of the rare earth elements from contaminants is performed through a variety of chemical processes. These include solvent extraction, ion exchange, and liquid-liquid extraction. In solvent extraction, the rare earth element is combined with a solvent and then separated from the impurities using a filter. In ion exchange, the rare earth element binds to an ion-exchange resin and is separated from other elements. Finally, liquid-liquid extraction involves the use of two immiscible liquids to separate out the rare earth element of interest.
The various steps involved in the separation and purification of rare earth elements make the process energy-intensive and expensive. To meet the ever increasing demand for these elements more efficient and cost-effective methods are needed. In recent years, numerous research institutions have begun to explore alternative methods of separation, including the use of advanced enzymes, biosorbents and ionic liquids. Such research could be key to making rare earth extraction and production more efficient, sustainable and cost effective.
