The present invention relates to a method of separating radioactive elements from a mixture, wherein the mixture is treated with at least one alkanesulfonic acid and at least one further acid, selected from the group consisting of hydrochloric acid, nitric acid, amidosulfonic acid and mixtures thereof and also the use of at least one alkanesulfonic acid and at least one further acid for separating radioactive elements from mixtures comprising these.

The present disclosure relates to nuclear chemical, particularly radiochemical, technologies at different stages of the nuclear fuel cycle, such as the production of purified nuclear materials (uranium, zirconium) or the reprocessing of spent nuclear fuel from nuclear power stations, in which extraction processes and operations for purifying nuclear materials are used. An example method, which includes the partial decomposition of nitric acid during continuous evaporation while a solution containing a reducing agent is fed into the bottom part of an evaporator having a circulating bottoms solution, consists in that the process is carried out such that the solution is kept in the bottom part of the evaporator for more than 2 hours under the addition of an aqueous solution of formaldehyde and formic acid (hereinafter “the mixture”) or a solution of formic acid after the process has been started using the mixture.

The present invention discloses a method for the separation of radionuclides from an aqueous radioactive waste solution, the method comprising: receiving of an aqueous radioactive waste solution, adding at least one zirconium salt to the aqueous radioactive waste solution, changing the pH of the radioactive waste solution to obtain a precipitate P, and separating the precipitate P from the radioactive waste solution. The present invention also discloses the use of zirconium salts, preferably zirconium oxychloride, zirconium nitrate or a zirconium oxynitrate or any mixture thereof, for the treatment of aqueous radioactive waste solution, preferably acidic or alkaline intermediate or low level radioactive waste solution, preferably an acidic intermediate and/or low level radioactive waste solution.

The invention pertains to a method for separating uranium and/or thorium from an aqueous suspension, said method comprising: a) Contacting said suspension with at least a polymer having formula (I), wherein n is an integer which is not 0 and is no more than 50, R1 is H or CH.sub.3, R2 is H or a C1-C20-alkyl, R3 and R4 arc independently H or a C1-C20-alkyl, X, Y arc O or NH, said polymer being soluble in said aqueous suspension, and wherein when R3 and R4 are H, p is an integer which is 1 or more and 10 at the most, and said polymer is a flocculating polymer, and when at least one of R3 and R4 is not H, p is an integer which is 3 or more and 10 at the most, and said polymer is a thermosensitive polymer and has a LCST in said suspension, b) Carrying out at least one of the following steps b1) and b2) b1) If said suspension contains uranium, separating the aggregates resulting from flocculation of said polymer, from said mixture, b2) If said suspension contains thorium, modifying the mixture until the LCST of the polymer in the mixture is reached or exceeded and separating the resulting aggregates from said mixture; and c) Recovering at least one of uranium and/or thorium-free mixture, aggregates bearing uranium and aggregates bearing thorium.

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Provided are methods to separate an isotope from a first solution including uranium. The methods may include (a) cleaning the first solution to form a second solution including the uranium and a third solution including the isotope; (b) oxidizing the third solution to form an oxidized isotope; and (c) separating the oxidized isotope.

The proposed invention relates to processes for extracting and concentrating radionuclides and can be used in radiochemical technologies when treating liquid radioactive waste. The method for isolating americium from liquid radioactive waste and for separating americium from rare earth elements in a single extraction cycle involves joint extraction of americium and rare earth elements from a nitric acid radioactive solution with a neutral solution of an organic extraction agent in a polar fluorinated solvent; washing an obtained organic phase saturated with metals; and selective back extraction of americium, wherein the extraction agent for joint extraction is N,N,N,N-tetraalkylamide of diglycolic acid, and a solution for back extraction is a composition of 5-20 g/l of a complexone, 5-60 g/l of a nitrogen-containing organic acid and 60-240 g/l of a salting-out agent.

A method for stripping U(VI) and an An(IV) from an organic solution including tri-n-butyl phosphate in an organic diluent, the solution containing U(VI) and the An(IV) present as U(VI) nitrate and An(IV) nitrate at concentrations such that the U(VI) nitrate concentration is higher than the An(IV) nitrate concentration, and the sum of the U(VI) nitrate and An(IV) nitrate concentrations is ?55 g/L. The method includes contacting the organic solution and an aqueous solution of nitric and oxalic acids, the oxalic acid concentration in the aqueous solution and the O/A volume ratio selected so that the oxalic acid is deficient with respect to the stoichiometric conditions of a complete precipitation of U(VI) and actinide(IV), to obtain a precipitate containing the actinide(IV) in oxalate form and a fraction of the U(VI) in oxalate form with a U(VI)/actinide(IV) mass ratio of between 0.5 and 5; and separating the precipitate from the organic and aqueous solutions.

The present invention is directed to supercritical fluid extraction systems that provide methods of extraction that further reduce total extraction time and improve yield efficiency as compared with existing methods. Such systems and methods utilize substantially increased pressures and flow rates that afford high intensity targeting of extractable material using supercritical carbon dioxide. Surprisingly, the present invention has identified and demonstrated dramatic improvements in the rate and efficiency of dissolution of the target compounds by increasing the pressure of supercritical fluid extraction systems to several times industry standards (e.g., 1000 bar versus 150-300 bar).

The present invention relates to a method of separating radioactive elements from a mixture, wherein the mixture is treated with at least one alkanesulfonic acid and at least one further acid, selected from the group consisting of hydrochloric acid, nitric acid, amidosulfonic acid and mixtures thereof and also the use of at least one alkanesulfonic acid and at least one further acid for separating radioactive elements from mixtures comprising these.

Provided herein are separation processes for metal ions present in aqueous solutions based on methods involving liquid-liquid extraction. The separation process involves a chelator that can selectively bind to at least one of the metals at a relatively low pH. This can be used, for example, for recovery and purification of actinides from lanthanides, separation of metal ions based on their valence, and separation of metal ions based on the pH of the extraction conditions.