GB741591A - Improvements in or relating to the purification of uranium by formation of uranium peroxide - Google Patents

Abstract

Pure uranium peroxide is prepared from impure uranium tetrafluoride by dissolving the latter in dilute sulphuric acid in the presence of excess hydrogen peroxide, precipitating ammonium uranate from the uranyl sulphate solution so formed by the addition of excess aqueous ammonia, washing the precipitate and dissolving it in sulphuric acid and adding hydrogen peroxide to precipitate uranium peroxide. The initial dissolution which may employ 125 per cent sulphuric acid and 400 to 600 per cent hydrogen peroxide of the stoichiometric requirements, is preferably conducted at 10 to 60 DEG C, the hydrogen peroxide addition preferably being in stages. The solution may then be boiled to decompose excess hydrogen peroxide. After the addition of ammonia to increase the final pH to 9 at least, a wetting agent such as trimethyl cetyl ammonium bromide or sodium oleyl para anisidine sulphonate may be added to facilitate precipitation of the ammonium uranate. This precipitate is freed from ammonium fluoride by washing and dissolved in sulphuric acid, to form uranyl sulphate. After adjusting the pH to 3.0 by the addition of aqueous ammonia, hydrogen peroxide is added. The precipitated uranium peroxde is filtered and may be dried at 140 DEG C. The initial impure uranium tetrafluoride may be derived from hydrofluorination of uranium dioxide or the precipitation of uranous sulphate solution with aqueous hydrogen fluoride.