Abstract: The invention relates to a process for the selective extraction of (III) actinides by means of amides having a nitrogenous heterocyclic substituent of formula: ##STR1## in which R.sup.1 is an alkyl or alkoxy group or a hydrogen atom, R.sup.2 and R.sup.3, which can be the same or different, represent a hydrogen atom, an alkyl or an alkoxy group and R.sup.4 is a hydrogen atom or a group of formula: ##STR2## in which R.sup.5 and R.sup.6, which can be the same or different, represent a hydrogen atom or an alkyl or alkoxy group. This process makes it possible to separate (III) actinides from (III) lanthanides.

Abstract: The invention relates to a process for the separation of actinides from lanthanides by the selective extraction of the actinides in an organic solvent incorporating a propane diamide.This process consists of adding to the aqueous nitric solution containing the actinides and lanthanides a thiocyanate, e.g. ammonium thiocyanate, followed by the contacting of said solution with an organic solvent incorporating at least one propane diamide, e.g. 2-tetradecyl-N,N'-dimethyl-N,N'-dibutyl-propane diamide and optionally a quaternary ammonium salt such as trilauryl methyl ammonium (TMA) thiocyanate or a mixture of quaternary ammonium thiocyanates.This leads to distribution coefficients D.sub.M for the actinides (Am) and the lanthanides (Eu, Ce) making it possible to achieve high actinide/lanthanide separation factors.

Abstract: The invention relates to a process for separating iron and/or zirconium from the actinides and/or lanthanides present in an aqueous acid solution by means of a propane diamide.According to the invention, use is made of a pentasubstituted propane diamide of formula: ##STR1## in which R.sup.1, R.sup.2 and R.sup.3, which can be the same or different, are alkyl radicals, which can have 1 or 2 oxygen atoms in their chain.To maintain the iron in aqueous solution, a choice is made of an appropriate propane diamide of formula (I) with R.sup.3 representing a C.sub.12 to C.sub.25 alkyl in order to have different extraction kinetics between Fe and the actinides or lanthanides, or an additive is added to the aqueous solution, e.g. oxalic acid or sodium nitrate.

Abstract: The invention relates to a process for the extraction of uranium (VI) and/or plutonium (IV) present in an acid aqueous solution by means of a mixture of N,N-dialkyl amides usable for the reprocessing of irradiated nuclear fuels.In (50 or 52) contacting takes place between an aqueous solution containing U(VI) and Pu(IV) and an organic solvent incorporating a mixture of two N,N-dialkyl amides, e.g. of formulas: ##STR1## and then by separating (in 50 or 52) the organic solvent containing either U(VI) and Pu(IV), or U(VI).

Abstract: The invention relates to the preparation and use of novel extracting agents and novel propane diamides for the recovery of actinides and/or lanthanides.These extracting agents are constituted by propane diamides of formula: ##STR1## For example, the extracting agent can be 2-hexyl-N,N'-dimethyl-N,N'-dibutyl-propane diamide or 2-ethoxyethyl-N,N'-dimethyl-N,N'-dibutyl-propane diamide.They are more particularly used for the recovery of actinides and/or lanthanides present in the trivalent state in an acid aqueous solution, particularly in a nitric solution.

Abstract: The invention relates to a process for the extraction of uranium (VI) and/or plutonium (IV) present in an aqueous solution by means of N,N-dialkylamides.These N,N-dialkylamides are in accordance with formula: ##STR1## in which R.sup.1 is a straight or branched alkyl radical with 2 to 12 carbon atoms, R.sup.2 and R.sup.4, which can be the same or different, are straight or branched alkyl radicals with 2 to 6 carbon atoms, R.sup.3 and R.sup.5, which can be the same or different, are straight or branched alkyl radicals with 1 to 6 carbon atoms and a and b, which can be the same or different, are integers between 1 and 6.For example, it is possible to use N,N-di-(2-ethyl hexyl)-2,2-dimethyl butyramide, N,N-di-(2-ethyl hexyl)-hexanamide or N,N-di-(2-ethyl hexyl)-dodecanamide for simultaneously extracting uranium and plutonium, or for separating the uranium from the plutonium without reducing the latter.

Abstract: The invention relates to novel extracting agents and novel propane diamides, their use for the recovery of actinides and/or lanthanides and their preparation process. These extracting agents are constituted by propane diamides of formula: ##STR1## For example, the extracting agent can be 2-hexyl-N,N'-dimethyl-N,N'-dibutyl-propane diamide or 2-ethoxyethyl-N,N'-dimethyl-N,N'-dibutyl-propane diamide. They are more particularly used for the recovery of actinides and/or lanthanides present in the trivalent state in an acid aqueous solution, particularly in a nitric solution.

Abstract: This invention relates to a process of recovering trivalent actinides, trivalent lanthanides or mixtures thereof from an aqueous acid solution by contacting the aqueous solution with an organic solution containing the diamides of the formula: ##STR1## where R is C.sub.2 -C.sub.10 alkyl. This process affords a good extraction efficiency level for the recovery of lanthanides and actinides, both of which are present in the trivalent state, or mixtures thereof, from installations for the reprocessing of irradiated nuclear fuels.

Abstract: A process for the separation of the actinides and lanthanides present in the trivalent state in an acid aqueous solution, wherein the actinides present in such aqueous solution are extracted selectively in an organic solvent by bringing the solution into contact with an organic solvent comprising a first extracting agent formed by an organic bonding agent having an electron-donor nitrogen atom and a second extracting agent formed by an acid organosoluble organic compound able to exchange its H.sup.+ ions for metal ions or by metallic salt of such compound.Application to the nuclear industry, inter alia in the field of the treatment of aqueous effluents containing lanthanides and actinides, such an transuranic elements.

Abstract: A method for the separation of actinides from lanthanides present in a trivalent state in an acidic aqueous solution.Said method consists in selectively extracting in an organic solvent the actinides present in said solution, by bringing said aqueous solution into contact with an organic solvent comprising a system of extractants constituted by an acidic organo-phosphorated compound containing at least one electron doner sulfur atom such as di-2-ethylhexyl-dithio-phosphoric acid, and by a neutral organophosphorated compound containing at least one electron-doner oxygen atom such as tributyl phosphate.

Abstract: Process for the plutonium decontamination of an organic solvent comprising adding to the said organic solvent a reducing agent which is a dialkyl dithiophosphoric acid and which is soluble in the organic solvent, bringing the organic solvent containing the reducing agent into contact with an acid aqueous solution and separating the aqueous solution containing the plutonium from the decontaminated organic solvent, useful in reprocessing of irradiated nuclear fuels.

Abstract: The invention relates to a process for the determination of uranium (VI) or dialkyl dithiophosphoric acid present in an organic solvent.In this process, a dialkyl dithiophosphoric acid or a uranium (VI) salt is added to the organic solvent so as to convert all the uranium or dialkyl dithiophosphoric acid present in said solvent into a mixed uranium (VI) - dialkyl dithiophosphoric acid-organophosphorus compound complex. The optical density of the solvent containing the complex in solution is measured so as to determine the concentration of this solvent in the complex, together with its uranium dialkyl dithiophosphoric acid content.Application to the determination of traces of uranium in tributylphosphate obtained from the reprocessing of irradiated fuels.

Abstract: Process for the recovery of the uranium present in a phosphoric acid solution by bringing the said solution into contact with an organic solvent suitable for extracting the uranium, wherein the said organic solvent comprises a system of extractants constituted by an acid organophosphorus compound having at least one sulphur atom and by a neutral phosphine oxide of formula: ##STR1## in which R.sub.1, R.sub.2 and R.sub.3 are identical or different alkyl, alkoxyalkyl or aryl radicals.

Abstract: Process for the separation of americium from curium contained in an aqueous nitric solution, wherein the initial solution undergoes oxidation at ambient temperature in the presence of phosphoric acid or phosphate ions at a concentration at the most equal to 0.1 mol per liter in such a way as to pass the americium at valency VI, the thus treated solution is brought into contact with a slightly reducing organic solvent having a high affinity for americium at valency VI in such a way as to extract the americium in the organic phase, the organic phase containing the americium at valency VI is then washed, followed by the re-extraction of the americium in the organic phase by means of an aqueous solution.

Abstract: Process for the recovery of the ruthenium present in an aqueous nitric solution, wherein the ruthenium is extracted in an organic solvent by contacting the nitric solution with an organic phase comprising an organophosphorous compound having at least one electron donor sulphur atom in the presence of a compound able to displace NO.sup.+ ions of the ruthenium complexes present in the nitric solution. Application to the recovery of ruthenium contained in a nitric solution obtained by dissolving irradiated fuel elements.