Patent ID: 7829043

Claim:
A method for coprecipitation or simultaneous precipitation of at least one actinide in oxidation state (IV) with at least one actinide in oxidation state (III), comprising: a) adding a singly charged stabilizing cation consisting of atoms selected from the group consisting of oxygen, carbon, nitrogen and hydrogen atoms, or a compound capable of forming said singly charged stabilizing cation, to one or more solutions of actinide(s) containing overall at least one actinide An 1 and at least one actinide An′ 1 , so as to obtain a solution or mixture, of at least one actinide An 1 in oxidation state (IV), at least one actinide An′ 1 in oxidation state (III) and said singly charged stabilizing cation, the value of the oxidation states (IV) and (III) having optionally been obtained during a preliminary or simultaneous step of chemical or electrochemical reduction; and b) adding a solution of oxalic acid or one of its salts or a derivative thereof to said solution or mixture, whereby coprecipitation or simultaneous precipitation of said actinides An 1 (IV) and An′ 1 (III) and a fraction of the singly charged stabilizing cation from said solution or mixture is carried out.