Solvent extraction process for separating hafnium from zirconium

Claim 1

IN THE PROCESS FOR SEPARATING HAFNIUM FROM ZIRCONIUM VALUES WHICH COMPRISES CONTACTING A FEED MATERIAL CONTAINING ZIRCONIUM AND HAFNIUM TETRAHALIDES, SAID TETRAHALIDES BEING SELECTED FROM THE GROUP CONSISTING OF TETRACHLORIDES, TETRABROMIDES AND TETRAIODIDES, WITH WATER TO FORM AN AQUEOUS FEED SOLUTION, CONTACTING SAID AQUEOUS SOLUTION IN A SEPARATION STEP WITH AMMONIUM THIOCYANATE, METHYL ISOBUTYL KETONE, AND HYDROCHLORIC ACID, AND SEPARATING THE RESULTING HAFNIUM-RICH PHASE FROM A ZIRCONIUMRICH, HAFNIUM-DEPLETED PHASE, THE IMPROVEMENT WHICH COMPRISES CONTACTING SAID AQUEOUS FEED SOLUTION, IN AN INTIAL EXTRACTION STEP AND PRIOR TO SAID SEPARATION STEP, WITH AN EXTRACTANT CONSISTING ESSENTIALLY OF A MATERIAL SELECTED FROM THE GROUP CONSISTING OF METHYL ISOBUTYL KETONE, ETHYL ETHER, ETHYL ACETATE, BUTYL ETHER AND BUTYL ACETATE, TO EXTRACT FERRIC IRON VALUES FROM SAID AQUEOUS FEED SOLUTION THEREBY PREVENTING POLYMER FORMATION WHEN SAID FEED SOLUTION IS TREATED IN SAID SEPARATION STEP, AND SEPARATELY RECOVERING A SUBSTANTIALLY FERRIC IRON-FREE AQUEOUS FEED SOLUTION AND AN EXTRACT PHASE CONTAINING SAID EXTRACTANT AND FERRIC IRON.