Synergistic integration of separations to recover dilute REEs

CMI researchers from Idaho National Laboratory conducted the activity for this highlight

Innovation 
Integrate recyclable crystallization trigger (dimethyl ether, DME) and reactive precipitation agent (Na2SO4) for synergistic recovery of dilute rare earth elements (REEs).

Achievements
1) Synergistic REE recovery can reduce the effective saturation solubility limit  to <10 ppm concentrations, lower than achieved by either trigger alone. 2) Determined optimal initial Na2SO4 concentration to induce REE precipitation in presence of DME.

Significance and Impact

  • DME FC integrated with Na2SO4 can recover low concentration REEs from unconventional sources (acid mine drainage, industrial wastewater, and mining byproducts) as well as enhance recovery from conventional sources. 
  • Next Steps: Optimize operating conditions, including pressure and temperature, to maximize REE yield and selectivity.

Hub Target Addressed 
Minimizing hazardous chemical use and waste generation.
 

image of bar graph showing reductions in aqueous concentrations of lanthanides after treatment with DME, 0.2 M Na2SO4 , or both DME and 0.2 M Na2SO4. Example shown here started with a concentrated solution containing mixed REE to facilitate REE quantification, but the data show the significant decrease in effective saturation solubility for the REE.
Reductions in aqueous concentrations of lanthanides after treatment with DME, 0.2 M Na2SO4 , or both DME and 0.2 M Na2SO4. Example shown here started with a concentrated solution containing mixed REE to facilitate REE quantification, but the data show the significant decrease in effective saturation solubility for the REE.