GB829093A - Recovery of uranium by precipitation as peroxide - Google Patents

Abstract

Uranium peroxide is precipitated from an aqueous uranyl salt solution, particularly the sulphate, containing magnesium and fluorine, in the presence of a substantial quantity of dissolved boric acid. Solutions containing 3-16% of uranyl sulphate are preferred and 4/10 to 1 mol. of boric acid per mol. of uranyl sulphate are preferably employed, the precipitation taking place at a pH between 2 and 4 by the addition of hydrogen peroxide or an alkali metal peroxide. Adjustment of the hydrogen ion concentration during precipitation may be effected by acid or alkali and the precipitation is preferably effected at 30-65 DEG C. According to examples: (1) uranium dross obtained in the manufacture of metallic uranium by the reduction of uranium tetrafluoride with metallic magnesium, with air roasted at 850 DEG C. and the oxide formed was treated with sulphuric acid to bring the pH to 0.9. A small amount of sodium peroxide was added and the mixture heated to 90-95 DEG C. after which calcium carbonate was added and the pH adjusted to 3.7 by the addition of concentrated sulphuric acid. The mixture was filtered hot, the filter cake was flooded with water and the filtrate from the slurry and the initial filtrate were combined to obtain a starting uranyl sulphate solution. A small amount of boric acid was added and precipitation was effected with a 28% aqueous solution of hydrogen peroxide, caustic soda being added to adjust and maintain the pH at 3. The product uranium peroxide contained 0.5% of fluorine. Specification 829,088 is referred to.