| 摘要 |
PROBLEM TO BE SOLVED: To extract and separate a light rare earth element with high separation efficiency, thereby: enabling extraction and separation through more simplified steps and in a small size plant, and reduction of installation investment and running cost; and causing great industrial worth.SOLUTION: A target light rare earth element is separated from light rare earth elements selected from lanthanum, cerium, praseodymium, and neodymium, by contacting an organic phase containing an extractant with the aqueous phase containing the light rare earth elements in a counter-current flow multistage mixer-settler while adding an alkaline solution thereto, for extracting a target extracting element in the organic phase, and contacting the organic phase with an acid aqueous solution for back-extracting the target extracting element. The extractant is a dialkyl diglycol amide acid having formula: RRNCOCHOCHCOOH wherein Rand Rare each independently a linear or branched alkyl group, and at least one of them is alkyl group having at least 6 carbon atoms. The amount of alkali in the alkaline solution and the amount of acid in the acid aqueous solution are 1.2 to 3.5 equivalents relative to the light rare earth elements in the aqueous phase. |
