METHOD FOR EXTRACTING AND SEPARATING LIGHT RARE EARTH ELEMENT

A target light rare earth element is separated from an aqueous solution containing two or more of La, Ce, Pr and Nd by contacting an organic phase containing an extractant with the aqueous solution in a counter-current flow multistage mixer-settler while adding an alkaline solution thereto, and contacting the organic phase with an acid aqueous solution for back-extracting the target element. The extractant is a dialkyl diglycol amic acid having formula : R 1 R 2 NCOCH 2 OCH 2 COOH wherein R 1 and R 2 are alkyl, at least one having at least 6 carbon atoms.