Patent ID: 8177881

Claim:
A method for extracting and separating rare earth elements, comprising the steps of: contacting an organic phase containing a diglycolamic acid having the general formula (1): wherein R 1 and R 2 are alkyl groups independent of each other, at least one of R 1 and R 2 is a straight or branched alkyl group of at least 6 carbon atoms as an extractant and an organic solvent with an aqueous phase containing at least first and second rare earth elements under acidic conditions of pH 3 or below, for extracting the first rare earth element into the organic phase, back-extracting from the organic phase with an aqueous acid solution for recovering the first rare earth element once extracted into the organic phase, and recovering the second rare earth element which has not been extracted into the organic phase and has remained in the aqueous phase, wherein provided that C 0 is a concentration of the diglycolamic acid extractant in the organic phase and C A is a concentration of rare earth elements in the aqueous phase, the extraction step is effected under the condition that a ratio of C 0 to C A is 2≦C 0 /C A ≦10 and C 0 is 0.1 mol/L≦C 0 ≦1.5 mol/L.