Extraction of Rare Earth Elements from Chloride Media with Tetrabutyl Diglycolamide in 1-Octanol Modified Carbon Dioxide

Abstract

Rare earth elements (REEs) are critical to our modern world. Recycling REEs from used products could help with potential supply issues. Extracting REEs from chloride media with tetrabutyl diglycolamide (TBDGA) in carbon dioxide could help recycle REEs with less waste than traditional solvents. Carbon dioxide as a solvent is inexpensive, inert, and reusable. Conditions for extraction of Eu from aqueous chloride media were optimized by varying moles percent of 1-octanol modifier, temperature, pressure, Eu concentration, TBDGA concentration, Cl− concentration, and HCl concentration. These optimized conditions were tested on a Y, Ce, Eu, Tb simulant material, REEs containing NdFeB magnets, and lighting phosphor material. The optimized conditions were found to be 23 °C, 24.1 MPa, 0.5 mol% 1-octanol, with an excess of TBDGA. At these conditions 95 ± 2% Eu was extracted from 8 M (mol/m3) HCl. Extraction from the mixed REE simulate material resulted in separation of Y, Eu, and Tb from the Ce which remained in the aqueous solution. The extraction on NdFeB magnet dissolved into 8 M HCl resulted in extraction of Pr, Nd, Dy, and Fe >97%. This results in a separation from B, Al, and Ni. Extraction from a trichromatic lighting phosphor leachate resulted in extraction of Y and Eu >93% and no extraction of Ba, Mg, and Al.

Recycling rare earths: Perspectives and recent advances

“…Leaching of rare earths has been explored with other solvent media, including supercritical fluids. 46,47 Rare-earth salts and oxides are only sparingly soluble in supercritical fluids; however, the addition of novel adducts, such as tri-n-butyl phosphate-nitric acid (TBP-HNO 3 ), to supercritical carbon Acid-free recycling of magnet waste to make new magnets. 42 dioxide or tetrabutyl diglycolamide in 1-octanol modified carbon dioxide can dramatically improve solubility.…”

“…Extraction of REE from NdFeB magnets and lighting phosphor material using these systems has been reported. 46 Again, formal published LCA or TEA is not available for this approach.…”

Determination of Rare Earth Elements Content in Hard Coal Type 31.1

“…The initial enrichment process takes an advantage of a gravitational method, using devices such as a jig, a spiral separator, a cone concentrator, a concentration table or a hydrocyclone. The obtained concentrate undergoes further processes, such as: flotation, leaching, magnetic-electrostatic separation or the use of concentrated acid solution and extraction with concentrated sodium hydroxide [4,6,15,17,20,21,23]. The final stage of the work aimed at recovering or obtaining the feed with a significant concentration of rare earth elements (from the selected material with prospective sufficient REE content) in the gravitational beneficiation process.…”

Rare Earth Elements Partition and Recovery During Electrodialytic Treatment of Coal Fly Ash

“…[27][28][29] Based on De Michelis, 30 REE should be dissolved in HCl or oxalic acid before being removed from the acidic solution using a ligand in a multi-stage solvent (ethanol) extraction process. 28 Then, REEs are calcined (at 700 °C for 4 h) to obtain REE in the form of oxides. 30 At the acid dissolved stage (Fig.…”