Acquisition of Rare Earth Elements by Application of Hydrometallurgical Methods

The demand for rare earth elements in the world is increasing rapidly, but the supply amounts of these elements are decreasing due to export quotas imposed by the Chinese government and illegal mining operations. Many countries have accelerated their efforts to obtain rare earth elements from primary and secondary sources in order to meet their future needs by taking measures. Rare earth elements are the most important components necessary both for the design and development of high-tech products that we use in our daily lives and for the advancement of modern industry. These elements, which have become indispensable materials of our lives, are generally not found in pure form in nature, but in complex structures in ores. Rare earth elements have close to 250 known minerals, but ores such as bastnasite, monazite and xenotime are commercially exploited. It is usually physically enriched by flotation, gravity, electrostatic or magnetic separation processes to obtain bastnasite, monazite and xenotime concentrates. In order to develop viable and environmentally friendly processes, studies are carried out for the extraction of rare earth elements from leaching solutions (chloride, nitrate, sulfate, thiocyanate, etc.) and the use of different cationic, anionic and neutral extractants depending on the solution medium. Commercial extraction of rare earth elements D2EHPA, Cyanex 272, PC-88A, Versatic 10, TBP, Aliquat 336 etc. carried out using different extractants. In this work, hydrometallurgical methods used for the recovery of rare earth elements from primary sources are examined. These methods are hydrometallurgical methods consisting of leaching with acids and alkalis followed by processes such as solvent extraction, ion exchange or precipitation and reduction. With the application of hydrometallurgical processes, processes that may be beneficial for the recovery of rare earth elements under various conditions have been evaluated.