Ion exchange process for separating the rare earths

Claim 1

IN AN ION EXCHANGE SYSTEM FOR SEPARATING AND PURIFYING RARE EARTH AND YTRIUM PRODUCT IONS FROM MIXTURES THEREOF, SAID SYTEM INCLUDING A PLURALITY OF OPERATIVELY INTERCONNECTING ZONES ARRANGED FOR SELECTIVE ISOLATION SUCCESSIVELY OF AT LEAST ONE OF SAID ZONES FROM THE OTHERS WITHOUT INTERRUPTION OF ION EXCHANGE AND SEPARATION IN SAID OTHER ZONES AND IN WHICH EACH OF THE ZONES CONTAINS A BED OF SOLID CATION EXCHANGE MEDIUM, THE IMPROVEMENT WHICH COMPRISES: (1) ESTABLISHING A NUMBER OF SUCCESSIVE SEPARATION ZONES BY LOADING THE SOLID BEDS IN SAID ZONES WITH QUANTITIES OF A SOLUTION CONTAINING A MIXTURE OF THE IONS WHICH ARE TO BE SEPARATED AND PURIFIED, SAID IONS BEING SELECTED FROM THE GROUP CONSISTING OF RARE EARTH AND YTRIUM IONS, (2) ESTABLISHING THE NEXT SUCCESSIVE ZONE AS A RETAINER ZONE BY LOADING THE SOLID BED THEREIN WITH QUANTITIES OF A SOLUTION CONTAINING A MIXTURE OF RETAINER IONS SELECTED FROM THE GROUP CONSISTING OF RARE EARTH AND YTRIUM IONS, THE RETAINER IONS HAVING AN EFFECTIVE ATOMIC NUMBER AT LEAST AS HIGH AS THE HIGHEST EFFECTIVE ATOMIC NUMBER OF THE IONS IN THE MIXTURE LOADED IN SAID SEPARATION ZONES, (3) ESTABLISHING ION EXCHANGE ELUTING SOLUTION SEQUESTERING AGENT COMPRISING AN AQUEOUS SOLUTION CONTAINING A RARE EARTH COMPLEX OF ETHYLENEDIAMINE TETRAACETATE ANIONS, THE IONS IN SAID ION EXCHANGE ELUTING SOLUTION HAVING AN EFFECTIVE ATOMIC NUMBER NO HIGHER THAN THE LOWEST EFFECTIVE ATOMIC NUMBER OF THE IONS IN THE MIXTURE LOADED IN SAID SEPARATION ZONES AND THE SOLUTION HAVING A PH RANGING FROM ABOUT 2.5 TO 4.5, (4) PASSING SAID ELUTING SOLUTION SUCCESSIVELY THROUGH SAID SEPERATION ZONES WHEREBY THE ELUTING SOLUTION ABSORBS THE IONS ORIGINALLY LOADED INTO THE SEPARATION ZONES WITH A CONSEQUENT DISPLACEMENT OF THE RARE EARTH ION CONTENT OF THE ELUTING SOLUTION INTO THE SOLID BEDS IN THE SEPARATION ZONES, (5) PASSING THE RESULTANT MODIFIED ELUTING SOLUTION THROUGH THE RETAINER ZONE TO EFFECT HEREIN AN ION EXCHANGE IN WHICH THE RETAINER IONS DISPLACE THE IONS PREVIOUSLY ABSORBED BY THE ELUTING SOLUTION WITH THE LATTER IONS BECOMING ASSOCIATED WITH THE SOLID BED IN THE RETAINER ZONE, AND (6) CONTINOUSLY ACIDFYING THE LIQUID MEDIUM EFFLUENT EXITING FROM THE RETAINER ZONES TO SEPARATE AN AQUEOUS SOLUTION OF THE RETAINER IONS FROM THE SEQUESTERING AGENT, (7) PASSING THE SEPARATED SEQUESTERING AGENT TO AN ELUTING SOLUTION PREPARATION AND SUPPLY ZONE FOR RECYCLE THROUGH SAID SEPARATION ZONE, AND (8) SEPARATING THE DESIRED SEPARATED AND PURIFIED RARE EARTH AND YTRIUM PRODUCT IONS FROM ASSOCIATION WITH THE SOLID BED AND RECOVERING THE SAME BY ION EXCHANGE WITH ELUTING SOLUTION FROM SAID PREPARATION AND SUPPLY ZONE.