New extractant, useful for extracting rare earths from an aqueous phosphoric acid solution, and the applications thereof

A method for extracting at least one rare earth from an aqueous phosphoric acid solution, comprising contacting the aqueous solution with a non-water miscible organic solution comprising an extractant in an organic diluent, then separating the aqueous solution and the organic solutions, in which the extractant comprises:

• a compound of formula (I):
• where:
• R1 and R2, either identical or different, are a saturated or unsaturated, linear or branched hydrocarbon group having 6 to 12 carbon atoms;
• R3 is:
• a saturated or unsaturated, linear or branched hydrocarbon group having 1 to 12 carbon atoms and optionally one or more heteroatoms;
• or
• a saturated or unsaturated, monocyclic hydrocarbon group having 3 to 8 carbon atoms and optionally one or more heteroatoms;
• R4 and R5, either identical or different, are a hydrogen atom, or a saturated or unsaturated, linear or branched hydrocarbon group having 2 to 8 carbon atoms;
• and
• a surfactant.

A method for recovering at least one rare earth from an aqueous phosphoric acid solution, comprising:

• extracting the at least one rare earth from the aqueous solution by contacting the aqueous solution with a non-water miscible organic solution comprising an extractant in an organic diluent, the extractant comprising:
• a compound of formula (I):
• where:
• R1 and R2, either identical or different, are a saturated or unsaturated, linear or branched hydrocarbon group having 6 to 12 carbon atoms;
• R3 is:
• a saturated or unsaturated, linear or branched hydrocarbon group having 1 to 12 carbon atoms and optionally one or more heteroatoms;
• or
• a saturated or unsaturated, monocyclic hydrocarbon group having 3 to 8 carbon atoms and optionally one or more heteroatoms;
• R4 and R5, either identical or different, are a hydrogen atom, or a saturated or unsaturated, linear or branched hydrocarbon group having 2 to 8 carbon atoms;
• and
• a surfactant;
• then by separating the aqueous solution and the organic solutions;
• and
• stripping the at least one rare earth from the organic solution by contacting the organic solution with an aqueous solution of oxalic acid or of a salt thereof, then by separating the aqueous solution and the organic solutions.