Separation of Hafnium From Zirconium by Anion Exchange

G . H evesy has written that [6] 1 " In view of the I.great similarity b etween hafnium and zirconium, i t ris hardly possible to separate these two elements in a lsingle operation ." A simple one-step separation c adequ a te for analytical work has still to be developed for hafnium-ziTconium mixtures, although recent work employing ion exchange has developed suitable methods for the separation of niobium from tantalum [5, 9, 10] and of molybdenum from tungs ten [2 , 9, "10], and a promising start has even been made on separating th e rare ear ths [12J. I Previous work on zirconium-hafnium mixtures has shown that fractionation on anion-exchange r esins can be ob ta ined by elution with aqueous solutions of hydrochloric and hydrofluoric acids [7, 8]; or by using diluted sulfuric acid, or nitric-citric acid solutions on cation-exchange resin-columns [1 , 11] . Preliminary work has shown that it is not feasible, ,within convenient column parameters and eluant acidities, to obtain a one-step separation in a hydrochloric acid medium, in hydrochloric-hych'ofluoric acid solutions, or in sulfuric-hydrofluoric acid solutions. Several differen t hydrochloric-sulfuric acid soluI tions appeared to providu usable separations, but ) difficulties were en countered which appeared to be associated with the polymeriza tion and eventual hydrolysis of zirconium ions. The results of experiments with sulfuric acid solutions indicate that a satisfactory separation of hafnium from zirconium can be obtained.