GB755601A - Separating hafnium from zirconium - Google Patents

Abstract

Zirconium and hafnium are separated by absorbing salts thereof on a cation exchange material and thereafter eluting the so treated material with 0.8 to 1.2N sulphuric acid whereby the bulk of the zirconium is removed in the initial eluate. The eluting solution may contain a soluble sulphate such as sodium sulphate. The hafnium remaining may be removed by elution with dilute hydrofluoric or oxalic acid and the cation exchanger may then be treated with a mineral acid such as nitric or sulphuric and the process repeated. According to an example, a cation exchange resin converted to acid form by nitric acid was treated with a hydrochloric, nitric or perchloric acid solution of zirconium oxychloride containing about 2 per cent hafnium. After the solution had passed through, aqueous normal sulphuric acid was passed through to yield an initial eluate containing 99 per cent of the zirconium which when precipitated as oxide contained less than 0.1 per cent hafnium. Alternatively the cation exchanger rendered acid with normal sulphuric acid may be charged with a 0.8 to 1.2 normal sulphuric acid solution of the zirconium and hafnium after which sulphuric acid of the same normality may be employed for elution. Similarly a nitric acid solution of the nitrates may be circulated through the upper of two cation exchanger columns both in acid form until the desired quantity of the metals are absorbed, and thereafter, normal sulphuric acid may be passed downwards through both columns to obtain an initial zirconium-containing eluate having a hafnium content of less than 0.05 per cent. The absorbed hafnium may be eluted with 0.5 per cent aqueous oxalic acid and the columns thereafter washed and treated with 2 normal nitric acid befor repeating the process.