SOLID-STATE REACTIONS OF URANIUM-OXIDES WITH AMMONIUM-SULFATE

Solid state reactions of uranium oxides of O/U ratio from 2.0 to 3.0 w ith ammonium sulphate were studied in an attempt to understand the nat ure of the oxidation state of uranium in them. The two end members, UO 2 and UO3, react at 250 degrees C to form (NH4)(4)U(SO4)(4) and (NH4)( 2)UO2(SO4)(2) and at 350 degrees C to form (NH4)(2)U(SO4)(3) and (NH4) (2)(UO2)(2)(SO4)(3), thereby retaining the oxidation state of uranium in the parent oxide. The intermediate oxides UO217, U4O9, U3O7 and U3O 8 react at the above two temperatures to form a mixture of ammonium ur anium double sulphates containing both U(IV) and U(VI) in the ratios s atisfying overall O/U values in the oxides. Chemical, X-ray, thermal a nd spectral methods were used to identify and characterise the product s.