Method for Recovering Thorium and Rare Earth Elements from Rare Earth Waste Residues

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A method for recovering thorium and rare earth elements from rare earth waste residues comprises : (1) mixing rare earth waste residues with an inorganic acid and heating to obtain a stock solution containing thorium and rare earth elements; (2) extracting thorium and rare earth elements from the stock solution with an organic phase containing an extractant; (3) washing the organic phase obtained after extraction in step (2) with a washing solution to move rare earth elements into the aqueous phase and remain thorium in the organic phase; (4) back-extracting the organic phase containing thorium obtained in step (3) with a back-extraction solution to move thorium in the organic phase into the aqueous phase; said extractants are alkyl phosphonic acid monoalkyl ester and dialkylphosphinic acid.