Process for separating rare-earth elements by ion exchange

Claim 1

A PROCESS FOR THE SEPARATION OF RARE EARTH METALS COMPRISING PROVIDING AT LEAST TWO CATION-EXCHANGE RESIN BEDS IN SERIES, CONTACTING THE FIRST BED WITH AN AQUEOUS SOLUTION OF SALTS OF THE RARE EARTH METALS TO ADSORB THE RARE EARTH IONS ON THE RESIN, CONTACTING THE SUCCEEDING RESIN BEDS WITH AN ACID CAPABLE OF PLACING THE RESIN IN THE HYDROGEN CYCLE TO PLACE THE RESIN IN THE HYDROGEN CYCLE MAINTAINING AT LEAST THE HYDROGEN CYCLE RESIN AT AN ELEVATED TEMPERATURE OF ABOUT 200*F. TO ABOUT 250*F., SUFFICIENT TO ENSURE SOLUBILITY OF THE ACID FORM OF EDTA, PASSING AN ELUANT COMPRISING AN AQUEOUS AMMONIACAL SOLUTION OF EDTA HAVING A PH IN THE RANGE OF ABOUT 6 TO ABOUT 9 THROUGH THE RARE EARTH CYCLE RESIN WHEREBY THE RARE EARTH IONS IN THE RESIN ARE COMPLEXED BY THE EDTA, SUBSEQUENTLY PASSING THE SOLUTION OF COMPLEXED RARE EARTH IONS THROUGH THE HYDROGEN CYCLE RESIN WHEREBY ION-EXCHANGE TAKES PLACE BETWEEN THE COMPLEXED RARE EARTH IONS IN SOLUTION AND THE HYDROGEN IONS ON THE HYDROGEN CYCLE RESIN, CONTINUING ELUTION WITH AN AQUEOUS AMMONIACAL EDTA SOLUTION HAVING A PH IN THE RANGE OF ABOUT 6 TO ABOUT 9 AND COLLECTING INITIALLY THE ACID FORM OF EDTA IN SOLUTION AND SUBSEQUENTLY SUCCESSIVE PORTIONS OF ELUATE EACH CONTAINING A SEPARATED RARE EARTH IN SOLUTION.