Processes for selective recovery of rare earth metals present in acidic aqueous phases resulting from the treatment of spent or scrapped permanent magnets

A method for selective recovery of at least one rare earth metal TR1 having an atomic number at least equal to 62 and of at least one rare earth metal TR2 having an atomic number at most equal to 61 from an acid aqueous phase A1, the aqueous phase A1 stemming from a processing of spent or scrapped permanent magnets and comprising one or more rare earth metals TR1, one or more rare earth metals TR2, transition metals and an acid having a concentration from 0.2 mol/L to 6 mol/L, the acid being nitric acid, sulphuric acid, hydrochloric acid, phosphoric acid or a mixture thereof, which method comprises:

• recovery of the rare earth metal TR1 from the aqueous phase A1, which recovery comprises:
• a) extracting the rare earth metal TR1 from the aqueous phase A1, the extraction comprising putting the aqueous phase A1 in contact with an organic phase S1 not miscible with water, which comprises a diglycolamide having a total number of carbon atoms at least equal to 24 as an extractant, in an organic diluent, and then separating the aqueous phase A1 from the organic phase S1;
• b) washing the organic phase S1 stemming from a), the washing comprising putting the organic phase S1 in contact with an acid aqueous phase A2, which comprises an acid identical with the acid of the aqueous phase A1, at a concentration at most equal to the strong acid concentration of the aqueous phase A1, and then separating the aqueous phase A2 from the organic phase S1;
• and
• c) stripping the rare earth metal TR1 from the organic phase S1 stemming from b), the stripping comprising putting the organic phase S1 in contact with an acid aqueous phase A3 which has a pH at least equal to 3, and then separating the aqueous phase A3 from the organic phase S1;
• and
• recovery of the rare earth metal TR2 from the aqueous phase A1 stemming from a), which recovery comprises:
• d) extracting the rare earth metal TR2 from the aqueous phase A1 stemming from a), the extraction comprising putting the aqueous phase A1 in contact with an organic phase S2 not miscible with water, which comprises an extractant identical with the extractant of the organic phase S1, in an organic diluent, and then separating the aqueous phase A1 from the organic phase S2;
• e) washing the organic phase S2 stemming from d), the washing comprising putting the organic phase S2 in contact with an acid aqueous phase A4, which comprises an acid identical with the acid of the aqueous phase A1, at a concentration at most equal to the acid concentration of the aqueous phase A1 stemming from a), and then separating the aqueous phase A4 from the organic phase S2;
• and
• f) stripping the rare earth metal TR2 from the organic phase S2 stemming from e), the stripping comprising putting the organic phase S2 in contact with an acid aqueous phase A5 which has a pH at least equal to 3, and then separating the aqueous phase A5 from the organic phase S2.

A method for selective recovery of at least one rare earth metal TR1 having an atomic number at least equal to 62 and of at least one rare earth metal TR2 having an atomic number at most equal to 61 from an acid aqueous phase A1, the aqueous phase A1 stemming from a processing of spent or scrapped permanent magnets and comprising one or more rare earth metals TR1, one or more rare earth metals TR2, transition metals and an acid having a concentration from 0.2 mol/L to 6 mol/L, the acid being nitric acid, sulphuric acid, hydrochloric acid, phosphoric acid or a mixture thereof, which method comprises:

• a) extracting the rare earth metal TR1 and the rare earth metal TR2 from the aqueous phase A1, the extraction comprising putting the aqueous phase A1 in contact with an organic phase S1 not miscible with water, which comprises a diglycolamide having a total number of carbon atoms at least equal to 24 as an extractant, in an organic diluent, and then separating the aqueous phase A1 from the organic phase S1;
• b) washing the organic phase S1 stemming from a), the washing comprising putting the organic phase S1 in contact with an acid aqueous phase A2, which comprises an acid identical with the acid of the aqueous phase A1, at a concentration at most equal to the acid concentration of the aqueous phase A1, and then separating the aqueous phase A2 from the organic phase S1;
• b′) stripping the rare earth metal TR2 from the organic phase S1 stemming from b), the stripping comprising putting the organic phase S1 in contact with an acid aqueous phase A5, which has a pH from 1 to 2.3, and then separating the aqueous phase A5 from the organic phase S1;
• b″) washing the aqueous phase A5 stemming from b′), the washing comprising putting the aqueous phase A5 in contact with an organic phase S2 not miscible with water, which comprises an extractant identical with the extractant of the organic phase S1, in an organic diluent, and then separating the aqueous phase A5 from the organic phase S2;
• c) stripping the rare earth metal TR1 from the organic phase S2 stemming from b′), the stripping comprising putting the organic phase S2 in contact with an acid aqueous phase A3 which has a pH at least equal to 3, and then separating the aqueous phase A3 from the organic phase S2.