| 摘要 |
PURPOSE:To separate rare earth elements easily and effectively, by extracting an acidic aqueous solution containing mixed rare earth metal chloride or nitrate with an acidic phosphoric acid ester thrice or more changing the concentration of the acid successively from low level to high level. CONSTITUTION:An acidic aqueous solution of the chloride or nitrate of mixed rare earth elements (e.g. Sm, Eu, Gd, Tb, Y, etc.) acidified with hydrochloric acid or nitric acid is extracted with an acidic phosphoric acid ester. The extraction is carried out by contacting the acidic solution with the ester thrice or more changing the concentration of the acid successively from low level to high level. The extractant is preferably an acidic phosphoric acid ester having different partition coefficient according to the acid concentration. Concretely, di-2-ethylhexyl phosphate is preferable for the separation of medium rare earth components (mainly from Sm to Dy) and 2-ethylhexyl phosphonic acid 2- ethylhexyl ester is preferable for the separation of heavy rear earth components (Y, Sc and elements heavier than Ho). The desired rare earth element can be obtained as single substance or a mixture of two or three elements.
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