GB1252081A - - Google Patents

Abstract

1,252,081. Extracting and purifying beryllium compounds. ANACONDA CO. 6 March, 1969 [6 March, 1968], No. 11939/69. Heading C1A. A process for extracting beryllium values from beryllium bearing material containing aluminium, iron, fluorine, zinc and other impurities by leaching with a mineral acid solution of pH 1À0 to 2À0 for a period sufficient to dissolve a substantial amount of the beryllium, the pH being maintained between 1À3 and 2. The solution obtained is suitably further treated by initially raising its pH to 3À0 to 4À5, causing precipita- 'tion of fluoro-compounds of aluminium and compounds of iron, separating the precipitates and then further raising the pH to 7À5 to 9À0 to precipitate beryllium hydroxide. A soluble fluoride may be added in the leaching step to improve the extraction of beryllium. A soluble sulphide may be added to the leach solution after the first pH raising step to precipitate zinc and other insoluble sulphides. The pH raising steps are suitably carried out using a base such as ammonia, alkali metal hydroxides, milk of lime or equivalent carbonates or oxides. The crude beryllium hydroxide precipitate may be purified either by (i) digestion in sodium hydroxide solution, followed by hydrolysis and reprecipitation, after 'optional further treatment with soluble sulphide or alternatively (ii) treatment with fuming sulphuric acid to give a precipitate of beryllium sulphate which is subsequently hydrolysed back to the hydroxide. In both of the above processes and also during the second pH raising step of the treatment of the leach liquor a further purification may be carried out by addition of a solution of a chelating agent, e.g. E.D.T.A., this preferably being carried out after sulphide treatment to eliminate those heavy metal ions whose chelates are not easily broken up for recovery of the chelating agent. The purified beryllium hydroxide is finally calcined to give the oxide.