Abstract: A method to activate U3O8 for conversion of this uranium oxide to hydrated UO4 via reaction with hydrogen peroxide H2O2, wherein the following successive steps are performed: a) an aqueous suspension is prepared containing a powder of U3O8 and hydrogen peroxide; b) the aqueous suspension containing a powder of U3O8 and hydrogen peroxide is contacted with ozone, whereby an aqueous suspension is obtained of a powder of activated U3O8; c) optionally the powder of activated U3O8 is separated from the aqueous suspension. A method to convert U3O8 to hydrated UO4 of formula UO4, nH2O where n is 2 or 4, comprising at least one step at which hydrogen peroxide H2O2 is added to the aqueous suspension of a powder of activated U3O8 obtained at the end of step b) of the activation method or to an aqueous suspension prepared by placing in suspension in water the powder of activated U3O8 obtained at the end of step c) of the activation method.

Abstract: A method to activate U3O8 for conversion of this uranium oxide to hydrated UO4 via reaction with hydrogen peroxide H2O2, wherein the following successive steps are performed: a) an aqueous suspension is prepared containing a powder of U3O8 and hydrogen peroxide; b) the aqueous suspension containing a powder of U3O8 and hydrogen peroxide is contacted with ozone, whereby an aqueous suspension is obtained of a powder of activated U3O8; c) optionally the powder of activated U3O8 is separated from the aqueous suspension. A method to convert U3O8 to hydrated UO4 of formula UO4, nH2O where n is 2 or 4, comprising at least one step at which hydrogen peroxide H2O2 is added to the aqueous suspension of a powder of activated U3O8 obtained at the end of step b) of the activation method or to an aqueous suspension prepared by placing in suspension in water the powder of activated U3O8 obtained at the end of step c) of the activation method.

Abstract: A method for converting UO3 and/or U3O8 into hydrated UO4 of formula UO4.nH2O wherein n is 2 or 4, comprising the following successive steps: a) preparing an aqueous suspension of a UO3 powder and/or a U3O8 powder; b) adding hydrogen peroxide H2O2 to the aqueous suspension of a UO3 and/or U3O8 powder, converting the UO3 and/or U3O8 into hydrated UO4 and precipitating, crystallizing the hydrated UO4 in the suspension; c) recovering the precipitate, crystals of UO4 hydrate; d) optionally, washing the recovered UO4 hydrate precipitate, crystal(s); e) optionally, repeating step d); f) optionally, drying the precipitate, the crystals; wherein the addition of H2O2 to the aqueous suspension is carried out so that the suspension contains a stoichiometric excess of H2O2 relatively to the stoichiometry of the reaction from UO3: UO3+nH2O+H2O2?UO4.nH2O+H2O??(1) or of the reaction from U3O8 UO2.67+1.33H2O2+nH2O?UO4.nH2O+1.

Abstract: A method for converting UO3 and/or U3O8 into hydrated UO4 of formula UO4.nH2O wherein n is 2 or 4, comprising the following successive steps: a) preparing an aqueous suspension of a UO3 powder and/or a U3O8 powder; b) adding hydrogen peroxide H2O2 to the aqueous suspension of a UO3 and/or U3O8 powder, converting the UO3 and/or U3O8 into hydrated UO4 and precipitating, crystallizing the hydrated UO4 in the suspension; g) recovering the precipitate, crystals of UO4 hydrate; h) optionally, washing the recovered UO4 hydrate precipitate, crystal(s); i) optionally, repeating step d); j) optionally, drying the precipitate, the crystals; wherein the addition of H2O2 to the aqueous suspension is carried out so that the suspension contains a stoichiometric excess of H2O2 relatively to the stoichiometry of the reaction from UO3: UO3+nH2O+H2O2?UO4.nH2O+H2O??(1) or of the reaction from U3O8 UO2.67+1.33H2O2+nH2O?UO4.