Rare earth elements (REEs) are strategic materials for energy-related applications such as photovoltaic solar cells, wind turbines, and hybrid automobiles. Geothermal brines are potentially significant sources of REEs. However, one of the difficulties in recovering REE is to concentrate the target elements, usually present at relatively low concentrations, which are contained in large volumes of geothermal fluids. The presence of very high concentrations of commodity salts like sodium chloride and magnesium sulfate in the geothermal brine makes the REE separation process more difficult. The recovery of REE from geothermal brine may also be difficult due to the chemistry of the elements. Even though methods have already been developed in the hydrometallurgical industry for recovery of REEs, little research has been conducted on processes to recover REE from geothermal sites. In this study, a novel electrochemical membrane process, electrodialysis metathesis (EDM), is investigated for the first time as an alternative to selectively separate and recover high purity REE from geothermal waters. In the process, the metathesis or double decomposition reaction was used to interchange salts of REEs with mineral salts through ion-exchange membranes placed between two electrodes. The new formed REE salts were further enriched and precipitated. The Solubility and pH placed an important role during the EDM process. Results from these research demonstrated that EDM desalination of REE-containing geothermal brines can provide enriched REE and also additional high quality desalted water.   <br/>

Electrodialysis metathesis for desalination of geothermal waters and recovery of rare earth elements: Role of pH and solubility

255th National Meeting (2018)

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