Development of a multicomponent thermodynamic database for molten salt processing of rare earths

two diagrams
Assessed Pr-Cl and Nd-Cl phase diagrams plotted against experimental datapoints. All phase boundary compositions and eutectic temperatures are within 5% of the experimental value, thereby validating our contribution to the CMI FA4 Year 14 goal.

CMI Highlight: Development of a multicomponent thermodynamic database for molten salt processing of rare earths

CMI researchers at Lawrence Livermore National Laboratory conducted the research for this highlight.

Innovation 
New model to optimize salt composition and operating temperature to maximize the La, Ce, Pr and Nd electrowinning efficiency in CaCl2, KCl and LiCl containing salts

Achievement
Developed a new open thermodynamic database (published in Calphad journal) to predict molten salt solubility and speciation in the (Ca-K-Li)-(La-Ce-Nd-Pr)-Cl composition space

Significance and Impact

  • Reduced cost and time to optimize new processing conditions (large design space) for production of RE metal via molten salt electrolysis (for project 2.2.8)
  • New model suggests that the molten salt composition can be tuned to bias RE deposition during the electrowinning process, potentially leading to an alternative separation technique

Hub Target Addressed 
Developing and applying scientific tools to accelerate technology maturation
https://doi.org/10.1016/j.calphad.2026.103003

two graphs
Electrolysis of 50PrCl3-50NdCl3 in CaCl2 at 1050 °C and eutectic 40KCl-60LiCl at 450 °C is predicted to give Nd-rich deposits.