Solvent extraction studies on separation of Nd and Pr from crude concentrate of rare earth

Light rare earth elements like Nd and Pr are pivotal for their uses in green energy technology such as wind turbines, energy efficient lighting devices etc. Cumulative demand of Nd-Fe-B permanent magnet in clean energy sector has resulted in bracketing the neodymium in critical materials category by US DOE. Often praseodymium is added in required proportion to the intermetallic magnetic alloys to increase the temperature at which the magnet can operate without losing its magnetic field. Therefore development of process to separate these rare earth elements is very much essential from different sources to address the issues pertaining to the predicted future shortfall. A concentrate namely Nd-Pr oxalate is obtained as by-product during purification of high purity La and Ce from rare earths chloride feed solution generated during processing of monazite. In the present work, EHEHPA has been selected as extractant while for feed solution oxalate concentrate was first converted to oxide prior to its dissolution in HCl. EHEHPA being an acidic extractant extracts metal ion by ion exchange mechanism, where the metal ion forms hydrobhobic complex with the dimer of extractant molecule while replacing the equal number of hydrogen ion into the aqueous solution leading to increase in acidity