Abstract
Lanthanides (Lns) are important to many technologies including magnets used in high-efficiency traction motors and generators. While commonly occurring in the environment and industrial waste streams, Ln are generally present at low concentrations. This work demonstrates synergistic Ln recovery from an aqueous magnet leachate to single ppm concentrations using Na(2)SO(4) addition and subsequent dimethyl ether-driven fractional crystallization (DME-FC) treatment. It is found that combining DME-FC with low concentrations of Na(2)SO(4) (≈0.1 M) results in synergistic isolation of Lns while making use of Na(2)SO(4), an excessive byproduct of hydrometallurgical metal production. Combined Na(2)SO(4) + DME reduces Ln metal ion (Pr, Nd, Sm, Gd, Dy, and Ho) solubilities by 700-27,000x with final concentrations ranging from 2 ppm to 200 ppm. Separately, Na(2)SO(4) 0.1 M provides a 10-200x reduction and DME provides a 90-1,400x reduction in Ln solubilities. Final Ln concentrations of the combined process are 99.8% lower than what is achieved with each individual process.