METHOD FOR EXTRACTING AND SEPARATING RARE EARTH ELEMENT

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PROBLEM TO BE SOLVED : To efficiently extract and separate light rare earth elements. SOLUTION : Organic phases 2, 8 comprising diglycolamide acid expressed by general formula (1) (R1 and R2 are an alkyl group(s) same or different from each other, and at least either denotes a ≥6C linear or branched alkyl group) as an extractant and a water phase 1 composed of an aqueous solution comprising two or more of rare earth elements are contacted under an acid condition at the pH of ≤3, the rare earth element(s) to be extracted is extracted into the organic phase, thereafter, the organic phase is back-extracted in acid aqueous solutions 4, 6 so as to recover the rare earth element(s) extracted into the organic phases, and, further, the rare earth element(s) not extracted into the organic phases and remaining in the water phase is recovered. At this time, the extraction treatment is performed in such a manner that the ratio between the concentration CO of the extractant in the organic phases and the concentration CA of the rare earth element(s) in the water phase is controlled to 2≤CO/CA≤10, and also, the CO is controlled to 0.1 mol/L≤CO≤1.5 mol/L. COPYRIGHT : (C)2011, JPO&INPIT