Preparation of Uranium Oxides in Nitric Acid Solutions by the Reaction of Uranyl Nitrate with Hydrazine Hydrate

摘要

UO_2·nH_2O formed by thermal denitration of uranyl nitrate in solutions under the action of hydrazine hydrate can be converted in air to UO_3 at 440℃ and to U_3O_8 at 570-800℃, and also to UO_2 in an inert or reducing atmosphere at 280-800℃. After the precipitation of hydrated uranium dioxide, evaporation of the mother liquor at 90℃ in an air stream allows not only evaporation of water, but also complete breakdown and removal of hydrazine hydrate and NH_4NO_3. The use of microwave radiation considerably reduces the time required for complete thermal denitration of uranyl nitrate in aqueous solution to uranium dioxide, compared to common convective heating.