REE adsorption experiments onto kaolinite with different ligands: implications on ion-adsorption REE deposits formation

摘要

Ion adsorption rare earth element (REE, La-Lu, Y) ores are the main source of heavy REE (HREE, Tb-Lu) and Y in the world (Sanematsu and Watanabe 2016). In an increasing demand on REE worldwide, especially towards the HREE, these deposits have gained interest because of the easy extraction of the ore, and the low radioactivity, which are usually characteristic of other REE deposits (Sanematsu and Watanabe 2016; Goode-nough et al. 2017). These deposits form after weathering of granitic bedrocks that contain magmatic and/ or hydrothermal REE-bearing minerals (e.g. phosphates, silicates and fluorocarbonates [Sanematsu and Watanabe 2016]). These minerals are altered and/or dissolved by acidic soil water (pH~4-6), releasing REE that can be incorporated into the solution as REE~(3+) ions, organic or inorganic aqueous complexes (Sanematsu and Watanabe 2016).