GB219327A - A process for separating hafnium and zirconium - Google Patents

Abstract

Hafnium and zirconium are separated by fractional crystallization, precipitation or sublimation of their halogen compounds other than double fluorides. A zirconium material containing hafnium may be treated with sulphuric acid, the hydroxides precipitated with ammonia and dissolved in hydrochloric acid and the solution evaporated and cooled whereby the oxychloride mixture separating out will be enriched in hafnium, and may be further treated by dissolving in hydrochloric acid and repeating the operation. Other hydrohalogenic acids may be used instead of hydrochloric acid. The oxychlorides may be precipitated from the aqueous or weakly acid solution by adding the corresponding strong hydrohalogenic acid or a soluble halogenide such as calcium halogenide or by adding alcohol or other suitable precipitant. Or a similar precipitation may be effected by adding water to a solution containing hafnium and zirconium in concentrated hydrohalogenic acid since the solubility is at a maximum at a certain concentration of acid. Alternatively, the mixed tetrahalogenides may be submitted to fractional sublimation, the non-volatilized portion being enriched in hafnium. The halogenides may be dissolved in water or in the corresponding hydrohalogenic acid, alcohol, or the like after which the process described above may be applied.