Synergistic and selective concentration of rare earth elements from the liquid to the solid phase

CMI researchers at Idaho National Laboratory conducted the research for this highlight

Innovation 
Integration of recyclable fractional crystallization (FC) trigger (dimethyl ether, DME) and reactive precipitation agent (Na2SO4) delivers synergistic recovery of rare earth elements (REEs).

Achievements
Synergistic REE recovery can reduce the effective saturation solubility limit to <10 ppm concentrations.

Significance and Impact

  • DME FC integrated with Na2SO4 recovers low concentration REEs from unconventional sources such as acid mine drainage, industrial wastewater, and mining byproducts as well as enhances recovery from conventional sources. 
  • Repurposing excess Na2SO4, which is a byproduct of hydrometallurgical metal production.

Hub Target Addressed 
Minimizing hazardous chemical use and waste generation.
 

bar graph, dot graph and line diagram show a mixed REE solution with the untreated (i.e., initial) aqueous concentrations of lanthanides as well as the aqueous concentrations after treatment with DME, 0.1 M Na2SO4, or both DME and 0.1 M Na2SO4. The bottom right figure shows the log reduction of REE concentrations which for the combined process is more than additive of the individual processes for the light REEs (Pr, Nd, Sm) demonstrating synergy. Example shown here started with a concentrated solution to facilitate quantification of treatment effects, but the data shows that this method would be effective against low concentration REE sources.
Starting from a mixed REE solution the bottom left figure shows the untreated (i.e., initial) aqueous concentrations of lanthanides as well as the aqueous concentrations after treatment with DME, 0.1 M Na2SO4, or both DME and 0.1 M Na2SO4. The bottom right figure shows the log reduction of REE concentrations which for the combined process is more than additive of the individual processes for the light REEs (Pr, Nd, Sm) demonstrating synergy. Example shown here started with a concentrated solution to facilitate quantification of treatment effects, but the data shows that this method would be effective against low concentration REE sources.