Abstract: A method for recovering nitrate ions as nitric acid from nuclear industry effluents by thermally decomposing the nitrate ions in solution, and recovering the NOx vapors generated by the heat treatment in an aqueous medium. The resulting nitric acid may be recycled in the nuclear industry.

Abstract: Process for obtaining fritted oxide pellets of the MxOy type for nuclear fuels from solutions of soluble salts of the element or elements M, involving stage of precipitating the elements M by hydrogen peroxide in an acid medium. During this precipitation, there is an instantaneous dispersion of one of the reagents (solution of salts or peroxide) in the other, in order to obtain a homogenous mixture and an also instantaneous precipitation of the nuclei in a continuous liquid phase confined in an enclosure having minimum dimensions, the mother liquors being rapidly exhausted. The process makes it possible to obtain sintered pellets whose density exceeds 96% of the theoretical density.

Abstract: A method for removing ruthenium from a uranium-containing solution comprising adding a nitrite to the solution and passing the solution over a quaternary ammonium or tertiary amine resin to selectively fix the ruthenium.

Abstract: A method of obtaining uranium metal from an oxidized uranium compound, characterized in that the oxidized compound is treated with chlorine and carbon at a first stage, to obtain a chloride which is reduced by electrolysis or metallothermy using a reducing metal at a second stage.

Abstract: A method of obtaining pellets of MxOy oxide, where M represents one or more elements used to make nuclear fuel pellets, as a means of obtaining very high density fritted pellets directly, i.e. without the intermediate powders being conditioned, comprising starting with a solution of soluble salts of the M elements, and treating them with hydrogen peroxide with the pH kept at from 2 to 2.5, in a continuous fluidized bed reactor comprising at least 3 superposed cylindrical sections of different diameters, the solutions in the central section being agitated vigorously, to obtain a precipitate which is subsequently calcined reduced, pressed then fritted.

Abstract: A process for the recovery of uranium which has been extracted from phosphate-bearing solutions by means of an organic solvent and which is re-extracted from said solvent by means of hydrofluoric acid is disclosed.The process is characterized in that sodium ions are introduced into the solution of hydrofluoric acid, while aluminum and magnesium ions may also be added to the sodium ions. That solution may be produced by recycling of a fraction of the suspension of fluoride from the re-extraction step, after having separated the solvent, and to which a make-up of sodium, aluminum and magnesium ions and hydrofluoric acid was added.

Abstract: The present invention relates to a proces for separating rare earths and uranium from a UF.sub.4 concentrate and for placing them into useful form, comprising attacking the UF.sub.4 concentrate with potassium hydroxide, followed by nitric acid dissolution of the resulting precipitate, and extraction of the solution using an organic solvent. The extraction results in an organic solution containing purified uranyl nitrate, and an aqueous solution from which rare earths are precipitated by means of a base.

Abstract: Uranium is recovered as UF.sub.4 from phosphate solutions. The uranium is reduced to the tetravalent state and extracted with an organic extractant. The uranium is recovered as UF.sub.4 by reextracting with an aqueous HF solution which includes UF.sub.4 in suspension for improved reextraction.

Abstract: A process for the recovery of the uranium present in phosphoric acid produced by a wet process in (A) by means of a suitable solvent (L.sub.9), which is carried out after separation of the gypsum in (B) formed in the attack operation, and elimination of the solid materials which are still in suspension, characterized in that, in order to avoid the formation of dross in the course of the operation of extracting the uranium which is previously reduced in (D), the step of eliminating the solid materials which are still in suspension is effected by a final solid-liquid separation operation in (C) and/or in (E), prior to extraction of the uranium in (F), in the presence of an added fraction of gypsum (S.sub.22) and/or (S.sub.23) resulting from the production of H.sub.3 PO.sub.4.

Abstract: A process for the removal of cadmium contained in wet-process phosphoric acid by flotation by means of a cadmium-collector anionic surface active agent and an injected gas in the presence of other impurities including iron and possibly uranium which is characterized in that, in order to improve the removal of cadmium, the iron contained in the phosphoric acid in the trivalent state is reduced to the divalent state before the cadmium collector is introduced into the medium to be purified by flotation.The collector agent is selected from the group of dithiophosphoric acid esters and the alkali metal salts thereof.

Abstract: A process for making into useful products the uranium and rare earths contained in impure uranium tetrafluoride resulting from the recovery of uranium from phosphoric acid, comprising dissolving it in a hot condition in a nitric medium in the presence of an aluminum compound, treating the resulting solution with a solvent for extracting uranyl nitrate, which contains a phosphoric ester, and separating from the aqueous phase from which the uranium is removed, the solvent which is charged with uranyl nitrate to be made into a useful product, which provides that, in order to achieve easy separation of the aqueous phase from which the uranium has been removed, from the uranyl nitrate extraction solvent:(a) The operation of dissolution of UF.sub.

Abstract: A method of dissolving impure uranium tetrafluoride in a hot state in a nitric acid solution in the presence of an aluminum compound. For the purpose of obtaining a uranyl nitrate solution which can easily be separated from the solid phase formed during treatment, the dissolving is carried out in two stages at an appropriate temperature. The first stage comprises introducing quantities of nitric acid and of the aluminum compound which are insufficient to dissolve the impure uranium tetrafluoride completely, and keeping the resultant suspension agitated for a period of at least 0.5 hour. The second stage comprises introducing quantities of nitric acid and of the aluminum compound which are at least sufficient to dissolve the uranium not dissolved in the first stage, while keeping the suspension agitated.

Abstract: A process for extracting the uranium contained in phosphoric acid solutions by means of an extracting agent comprising an alkylpyrophosphoric acid, which comprises bringing into contact, in an agitated condition, the inorganic, phosphoric acid phase and an organic phase containing the extracting agent, thereby producing an emulsion, which is characterized in that, in an extraction unit comprising n stages in a cascade configuration, for each extraction stage, the emulsion is produced in a first step by simultaneously subjecting the two phases for a period of time T.sub.1 to an intense mechanical shearing action corresponding to a shearing coefficient of at least 5000 seconds.sup.-1 in order to multiply the contact surfaces for contact between said two phases, and then said emulsion in a second step is abruptly broke in a time T.sub.2, the sum of the times required for carrying out the two steps being at most 20 minutes.

Abstract: A process for treating a hydrometallurgical suspension resulting from the acid attack on an ore containing at least one metal element to be put to use, and non-attackable mineral materials, a fraction of which is formed of clays, comprising extracting the useful metal element which has gone into solution in the attack operation, by means of an organic solvent belonging to the group of alkyl phosphates, which is characterized by introducing a condensed mineral phosphate into the ore attack medium, for the purpose of limiting the losses due to adsorption of the organic extraction solvent by the clays.The process applies more particularly to uraniferous, molybdeniferous, vanadiferous and cobaltiferous ores.

Abstract: The present invention relates to a process for the selective separation of uranium and molybdenum which are contained in an extract resulting from an amino solvent liquid-liquid extraction of a solution resulting from an attack on a molybdo-uraniferous ore by means of sulphuric acid, and which comprises re-extraction of the uranium in the presence of an oxidizing agent by means of an acid solution of an alkali metal chloride, followed by re-extraction of the molybdenum by means of an alkali metal carbonate solution. This process is characterized by using an oxidizing agent such as hydrogen peroxide, a small amount of which is added to the acid alkali metal chloride solution before the latter is brought into contact with the extract. This makes it possible to achieve selective separation of the uranium and molybdenum.

Abstract: A process for separating by means of an organic agent the uranium and the molybdenum contained in an aqueous liquor originating from a sulphuric attack of an urano-molybdeniferous ore which involves placing the said attacking liquor in contact with an organic extraction solution containing at least one tertiary or secondary amine in an (amine)/(Mo) molar ratio of up to 0.8, separating the molybdenum-charged organic phase from the uranium-rich aqueous phase, treating the organic phase with an aqueous liquor containing at least one mineral agent in the form of alkaline and ammonium hydroxide and/or carbonates to form an aqueous solution which is concentrated in molybdate.

Abstract: Processes for treating nitric effluents from plants so that a non-polluting stream is obtained and nitric values are recovered, which processes comprise acidifying nitric effluent, liquid-liquid extraction of the acidified effluent with an extraction agent comprising a neutral phosphoric ester and at least one long-chain alkylamine, and re-extraction of the loaded extraction agent with ammonia, thereby regenerating the extraction agent and providing ammonium nitrate, while at the same time providing a substantially nitric-free effluent.

Abstract: Wet-process phosphoric acid is purified sufficiently to take the place of purified thermal-process acid by a method which comprises (1) contacting an initial aqueous phase of a crude wet-process phosphoric acid with a water-immiscible solvent for phosphoric acid and allowing phosphoric acid and anionic impurities to be extracted or charged into said solvent leaving the cationic impurities in the first aqueous phase; (2) mechanically separating the charged solvent from the initial aqueous phase and contacting the charged solvent with water to allow the phosphoric acid and anionic impurities to be re-extracted into a second aqueous phase; (3) contacting the second aqueous phase with a water-immiscible alkaline liquid medium and allowing the anionic impurities to be transferred to said alkaline medium; and (4) mechanically separating the second aqueous phase containing pure phosphoric acid.