Extraction Chromatographic Materials for Clean Hydrometallurgical Separation of Rare-Earth Elements Using Diglycolamide Extractants

Journal Article · Tue Oct 01 00:00:00 EDT 2019 · Industrial & Engineering Chemistry Research

DOI:https://doi.org/10.1021/acs.iecr.9b04528· OSTI ID:1607020

Momen, Abdul  ^[1]; Healy, Mary  ^[1]; Tsouris, Costas  ^[1]; Jansone-Popova, Santa  ^[1]; DePaoli, David  ^[1]; Moyer, Bruce A.  ^[1]

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1. ORNL

The uncertain supply of the rare-earth elements (REE) from conventional sources such as bastnaesite and monazite demands the search for alternative sources. Unconventional sources such as phosphate rock and mine tailings have REE contents at the level of only hundreds to a thousand parts per million, which challenges the conventional REE separation methods such as solvent extraction (SX) and ion exchange (IX). Alternatively, the potential of extraction chromatography (EXC) has been explored, as it combines the selectivity of SX and the convenience of column techniques of IX. Herein, we report a novel EXC material incorporating N,N'-dimethyl-N,N'-dioctyl-3-oxa-diglycolamide (DMDODGA) into a porous solid support because DMDODGA exhibits higher extraction efficiency for REE in SX than does conventional N,N,N',N'-tetraoctyl-3-oxa-diglycolamide (TODGA) and as also compared with similarly made conventional TODGA-based EXC material. The extraction of mixed REE by DMDODGA and TODGA resins was evaluated in H₂SO₄, HCl, and HNO₃ media as a function of acid concentration. The REE feed concentrations were adjusted to achieve stoichiometric REE concentration and excess REE concentration, conditions that reflect near or complete saturation of resin capacity. In general, extraction at the same acid concentration followed the order HNO₃ > HCl > H₂SO₄. The extraction strength of the DMDODGA resin is significantly higher than that of the TODGA resin in all three examined mineral acids, especially at lower H₂SO₄ and HCl concentrations (0.01 and 0.1 M), making it a promising EXC material for hydrometallurgical extraction of REE.

• Research Organization: Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
• Sponsoring Organization: USDOE
• DOE Contract Number: AC05-00OR22725
• OSTI ID: 1607020
• Journal Information: Industrial & Engineering Chemistry Research, Vol. 58, Issue 43
• Country of Publication: United States
• Language: English