GB834271A - Process for the separation of the elements zirconium and hafnium - Google Patents

Abstract

Zirconium and hafnium are separated from one another by partitioning their thiocyanates between water and an organic solvent, wherein the operation is carried out in the substantially complete absence of sulphate ions and in the presence of at the most 48 g.p.l. of chloride ions. The hafnium is preferably extracted into the organic phase. The zirconium and hafnium may be supplied to the partitioning as the chlorides or oxychlorides by having present a water-soluble thiocyanate, preferably ammonium thiocyanate, or thiocyanic acid, in a solution of which the zirconium or hafnium salt is dissolved. It is convenient to carry out the partitioning using an aqueous solution free from all foreign ions. Such a solution may be obtained by the double decomposition of equivalent solutions of barium thiocyanate and of zirconium-hafnium sulphates, or by a double decomposition followed by extracting the solution with an organic solvent which will only extract the zirconium-hafnium thiocyanate formed, or by preparing the zirconium-hafnium thiocyanate solution by ion-exchange, or by dissolving their hydroxides in a solution of thiocyanic acid either in water or in the organic solvent used for the partitioning. It is advantageous that the organic solvent contains thiocyanic acid, preferably in a concentration of 1N to 2N, before partitioning. The partitioning may be carried out by known procedures. A large number of suitable organic liquids for the partitioning are referred to, including diethyl ether, methyl-n-propyl ketone, n-butanol, cyclohexanol, n-butyl acetate, amyl acetate, ethyl isopropyl ketone, methyl isobutyl ketone, benzaldehyde, and a mixture of methyl-n-propyl ketone and benzene. After the partitioning the zirconium and any remaining hafnium may be precipitated from the aqueous phase with ammonia, and the filtrate may be acidified and employed afresh for the preparation of solution for partitioning.