Extraction process for cerium

Claim 1

A METHOD OF PREPARING PURE CERIUM METAL FROM AN IMPURE CERIUM COMPOUND, COMPRISING CONVERTING SAID CERIUM COMPOUND INTO AN AQUEOUS CERIC SOLUTION; ADDING NITRIC ACID AND A NITRATE TO SAID AQUEOUS SOLUTION IN QUANTITIES SO AS TO ADJUST THE CONCENTRATIONS TO RANGE FROM 0.2 TO 2 M FOR THE CERIUM SALT, FROM 0.05 TO 8 M FOR SAID NITRATE, AND UP TO 6 M FOR THE NITRIC ACID; CONTACTING SAID AQUEOUS SOLUTION WITH ALKYL PHOSPHATE WHEREBY SAID CERIUM SALT IS EXTRACTED BY SAID PHOSPHATE; SEPARATING SAID ORGANIC SOLVENT PHASE FROM SAID AQUEOUS PHASE; REDUCING THE CERISALT IN SAID ORGANIC PHASE TO THE CEROUS STAGE BY ADDING AN AQUEOUS SOLUTION OF A REDUCING AGENT, WHEREBY THE CEROUS SALT FORMED IS EXTRACTED BY SAID AQUEOUS SOLUTION; SEPARATING SAID AQUEOUS PHASE FROM SAID PHOSTPHATE PHASE; REMOVING TRACES OF PHOSPHATE FROM SAID AQUEOUS PHASE BY TREATING IT WITH A SUBSTANTIALLY WATER-IMMISCIBLE ORGANIC SOLVENT FOR SAID PHOSPHATE; REMOVING SAID SOLVENT PHASE FROM SAID AQUEOUS PHASE; PRECIPITATING THE CERIUM AS THE OXALATE BY THE ADDITION OF CALCIUM OXALATE TO SAID AQUEOUS SOLUTION; IGNITING THE PRECIPITATE THUS FORMED WHEREBY PURE CERIUM DIOXIDE IS OBTAINED; TREATING SAID CERIUM DIOXIDE WITH HYDROFLUORIC ACID, WHEREBY CERIUM FLUORIDE IS FORMED; AND THEN REDUCING SAID CERIUM FLUORIDE WITH METAL SELECTED FROM THE GROUP CONSISTING OF ALKALI METAL AND ALKALINE EARTH METAL.