Method of separating rare earths by ion exchange

Claim 1

A PROCESS OF SEPARATING VARIOUS RATE EARTH METAL VALUES HAVING ATOMIC NUMBERS OF FROM 57 THROUGH 60, FROM 68 THROUGH 71 AND INCLUDING YTTRIUM VALUES FROM EACH OTHER, COMPRISING PASSING AN AQUEOUS FEED SOLUTION CONTAINING A MIXTURE OF SAID RARE EARTH METAL VALUES THROUGH A CATION EXCHANGE RESIN IN THE HYDROGEN FORM WHEREBY SAID RARE EARTH METAL VALUES ARE ADSORBED ON SAID RESIN, FLOWING AN AQUEOUS SOLUTION OF N-HYDROXYETHYLETHYLENEDIAMINETRIACETIC ACID ANIONS AS AN ELUANT THROUGH SAID RESIN WHEREBY THE RARE EARTH METAL VALUES ARE CHELATED AND DESORBED FROM THE RESIN IN THE ORDER OF DECREASING ATOMIC NUMBER, YTTRIUM BEHAVING AS AN ELEMENT OF AN ATOMIC NUMBER OF BETWEEN 60 AND 62 IN THAT IT FALLS BETWEEN ND AND SM, WHEREBY AN EFFLUENT IS OBTAINED, COLLECTING SAID EFFLUENT IN FRACTIONS, PASSING AN AQUEOUS AMMONIA SOLUTION OVER SAID RESIN WHEREY FREE N-HYDROXYETHYLETHYLENEDIAMINETRIACETIC ACID IS RECOVERED FROM RESUE AND THE RESIN IS CONVERTED TO THE AMMONIUM FORM, PASSING SULFURIC ACID OVER THE RESIN WHEREBY IT IS CONVERTED TO THE HYDROGEN FORM AND MADE READY FOR REUSE, ADDING OXALIC ACID TO THE EFFLUENT WHEREBY RARE EARTH METAL VALUES PRECIPITATE, SEPARATING THE PRECIPITATED RARE EARTHS FROM THE SUPERNATANT EFFLUENT, CONTACTING THE SUPERNATANT EFFLUENT WITH ADDITIONAL CATION EXCHANGE RESINS WHEREBY ANY NONPRECIPITATED RARE EARTH METAL VALUES AND N-HYDROXYETHYLETHYLENEDIAMINETRIACETIC ACID ANIONS ARE ADSORBED WHILE THE OXALIC ACID ANIONS PASS THROUGH THE ADDITIONAL CATION EXCHANGE RESINS AND LEAVE IT IN THE EFFLUENT, CONTACTING THE ADDITIONAL CATION EXCHANGE RESIN WITH AN AQUEOUS SOLUTION OF N-HYDROXYETHYLETHYLENEDIAMINETRIACETIC ACID ANIONS WHEREBY SAID RARE EARTHS ARE DESORBED AND WASHED OFF SAID ADDITIONAL CATION EXCHANGE RESIN, CONTACTING THE ADDITIONAL CATION EXCHANGE RESIN WITH AN AQUEOUS SOLUTION OF AMMONIA WHEREBY THE N-HYDROXYETHYLETHYLENEDIAMINETRIACETIC ACID ANIONS ARE REMOVED AND RECOVERED FROM THE RESIN, AND REGENERATING THE RESIN TO ITS HYDROGEN FORM BY PASSING SULFURIC ACID OVER IT.