Patent GB-226180-A (GB)
Title: Improved process of separating a mixture of hafnium and zirconium compounds
IPC: C01G25/00
Filed: 1924-11-20
Abstract: The Specification as open to inspection under Sect. 91 (3) (a) describes the production of complex pyridine compounds by treating with pyridine the complex acids obtained by dissolving a mixture of hafnium and zirconium phosphates, phosphites, arsenates, arsenites, antimonates or antimonites in hydrofluoric acid.  They are separated by fractional crystallization or fractional precipitation.  This subject-matter does not appear in the Specification as accepted.ALSO:Hafnium and zirconium are separated by starting from a mixture of the complex acids that may be obtained by treating the phosphates with hydrofluoric acid, the anion of which contains hafnium or zirconium, phosphorus and fluorine; by adding hydrofluoric and phosphoric acids to soluble hafnium and zirconium compounds or from salts of these complex acids which may be obtained by replacing the cation by a metal for instance by neutralizing the complex acids with bases or by treating hafnium and zirconium phosphates with a fluoride such as bifluoride in presence of acid.  In a similar manner the corresponding compounds which may be obtained from the phosphites, arsenates, arsenites, antimonates and antimonites of hafnium and zirconium may be employed.  The separation of the hafnium and zirconium compounds is effected by fractional crystallization or fractional precipitation.  In the example the following are separated by fractional crystallization, the complex acids derived from the phosphates, the ammonium salts derived from the phosphates (prepared by treating the phosphates with ammonium bifluoride), the lithium salts derived from the phosphates, the barium salts derived from the phosphates, and the ammonium salts derived from the arsenates.  As in the complex compounds derived from the orthophosphates, one molecule of P2O5 is present with one molecule of ZrO2 or HiO2, and in the orthophosphates as obtained by precipitation there is a smaller proportion of P2O5, other hafnium or zirconium compounds containing less or perhaps no phosphorus will be produced as well when the complex phosphate compounds are prepared, and such compounds may also be formed by hydrolysis from the complex compounds when these are being separated by fractional crystallization.  For instance, in the separation of the ammonium salts derived from the phosphates, hafnium-ammonium fluoride and zirconium ammonium fluoride may be produced by hydrolysis.  Such compounds do not interfere with the separation. Specification 225,187 is referred to.  The Specification as open to inspection under Sect. 91 (3 (a) includes the following matter which does not appear in the Specification as accepted: Of the complex salts derived from the phosphates, the ammonium salts may be prepared by neutralizing the complex acids by ammonia or ammonium carbonate; the lithium salts by neutralizing the complex acids or by treating the ammonium complex salts with lithium chloride; the barium salts by treating soluble salts of the complex acids with barium hydroxide; and the pyridine salts by treating the complex acids with pyridine.