ie9b04528_si_001.pdf (118.23 kB)
Extraction Chromatographic Materials for Clean Hydrometallurgical Separation of Rare-Earth Elements Using Diglycolamide Extractants
journal contribution
posted on 2019-10-18, 19:16 authored by M. A. Momen, M. R. Healy, C. Tsouris, S. Jansone-Popova, D. W. DePaoli, B. A. MoyerThe
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.