A dissymmetric RN,N-dialkylamides of formula (I) in which: R.sup.1 represents a linear C.sub.1 to C.sub.4 alkyl, R.sup.2 represents a linear C.sub.1 to C.sub.10 alkyl, and R.sup.3 represents a linear or branched C.sub.6 to C.sub.15 alkyl, where R.sup.3 is different from a n-octyl, n-decyl, n-dodecyl, 2-ethylhexyl and 2-ethyloctyl group when R.sup.1 represents a n-butyl group and R.sup.2 represents an ethyl group. A method for synthesising the N,N-dialkylamides, and uses of same for extracting uranium and/or plutonium from an aqueous acid solution or for fully or partially separating the uranium from the plutonium contained in an aqueous acid solution and a solution resulting from the dissolution of spent nuclear fuel in nitric acid. A method for treating an aqueous solution resulting from the dissolution of spent nuclear fuel in nitric acid, which allows the uranium and the plutonium contained in the solution to be extracted, separated and decontaminated in a single cycle.

Methods for forming particulates that are highly consistent with regard to shape, size, and content are described. Particulates are suitable for use as reference materials. Methods can incorporate actinides and/or lanthanides, e.g., uranium, and can be used for forming certified reference materials for use in the nuclear industry. Methods include formation of an aerosol from an oxalate salt solution, in-line diagnostics, and collection of particles of the aerosol either in a liquid impinger or on a solid surface.

A method and system are provided for the creation of vertical and horizontal freeze wells, in a dome-like pattern around the ore body, as a hydraulic barrier to ensure the ISR mining solution and the mined minerals do not flow out of the ore body. A method to formulate a suitable mining solution used for ISR mining, where the lixivant does not freeze when using the freeze dome containment method and where the resulting PLS has a high concentration of dissolved minerals and thus eliminates the need for the solvent extraction/ion exchange step during processing is also described.

The present invention relates to use of a chelating compound for chromatographic separation of rare earth elements, actinides, and/or s-, p- and d-block metals, and to a method of chromatographic separation of chelates of rare earth elements, actinides and/or s-, p- and d-block metals from a mixture of at least two metal ions. The method is characterized in that it comprises the following steps: (a) providing a mixture of at least two different metal ions chosen from rare earth metal ions, actinide ions and/or s-, p- and d-block metal ions, (b) contacting metal ions comprised in said mixture to with at least one compound of general formula (I) as defined in any one of the preceding claims to form chelates; (c) subjecting the chelates from step (b) to chromatographic separation, wherein optionally at least one separated metal chelate obtained in step (c) can be subjected to at least one further chromatographic separation in order to increase the purity of the at least one separated metal chelate; and, optionally, (d) obtaining the metal from the at least one separated metal chelate.

The present invention relates to use of a chelating compound for chromatographic separation of rare earth elements, actinides, and/or s-, p- and d-block metals, and to a method of chromatographic separation of chelates of rare earth elements, actinides and/or s-, p- and d-block metals from a mixture of at least two metal ions. The method is characterized in that it comprises the following steps: (a) providing a mixture of at least two different metal ions chosen from rare earth metal ions, actinide ions and/or s-, p- and d-block metal ions, (b) contacting metal ions comprised in said mixture to with at least one compound of general formula (I) as defined in any one of the preceding claims to form chelates; (c) subjecting the chelates from step (b) to chromatographic separation, wherein optionally at least one separated metal chelate obtained in step (c) can be subjected to at least one further chromatographic separation in order to increase the purity of the at least one separated metal chelate; and, optionally, (d) obtaining the metal from the at least one separated metal chelate.

The present invention relates to a process for recovering metals from metal-bearing material, said process comprising the step of contacting the metal-bearing material with condensed phosphoric acid at a temperature of greater than 215° C. and less than 300° C. for a period of time sufficient to at least partially dissolve the metal-bearing material; to provide a leaching solution containing metal ions. The invention is applicable to a range of metals including the rare earth elements, as well as thorium and uranium. The invention is applicable to a range of metal-bearing materials, particularly phosphate minerals such as monazite and xenotime.

A process for recovering uranium from components contaminated with uranium oxide includes providing a cleaning apparatus with a cleaning solution for dissolving the uranium oxide of the components, carrying out a cleaning process by introducing a batch of components into the cleaning apparatus, and carrying out a measurement for determining the uranium content of the components. The cleaning and the measuring are repeated if a limit value for the uranium content is exceeded. The components are discharged from the process if the uranium content falls below a limit value. The cleaning is carried out on a plurality of successive batches of components until a control measurement indicates an unsatisfactory cleaning action of the cleaning solution. The uranium oxide dissolved in the cleaning solution is recovered after indication of the unsatisfactory cleaning action.

A method for separating thorium and cerium from a solid concentrate comprising compounds of thorium, cerium and further rare earth metals, comprising: a) contacting the solid concentrate with an acid to achieve an acid composition with a pH of less than 0.5; b) reacting the acid composition obtained in step a) with ozone or heating the acid composition at a temperature ranging from 110° C. to 130° C. for a time period ranging from 1 to 3 hours, thereby oxidizing the cerium ions in the acid composition to an oxidation state of +IV; c) increasing, to at most 2, the pH of the composition obtained in step b), resulting in the precipitation of thorium and cerium compounds; and d) separating the precipitated thorium and cerium compounds from the composition obtained in step c) to obtain an aqueous acidic rare earth solution depleted in thorium and cerium.

The use of carbamides as extractants for fully or partially separating uranium(VI) from plutonium(IV) in an aqueous solution obtained by dissolving a spent nuclear fuel in nitric acid, by method of liquid-liquid extraction, without carrying out any reduction of the plutonium(IV) to plutonium(III). The invention also relates to new carbamides. Uses are the processing of spent nuclear fuels based on uranium (especially uranium oxides—UOX) or uranium and plutonium (especially mixed uranium and plutonium oxides—MOX).

The present disclosure describes a method of recovering uranium including a continuous ion exchange (CIX) process including a single cycle or a dual cycle CIX process and at least a gradient elution or resin crowding process. The present disclosure also describes an apparatus including a single cycle or dual cycle CIX system and a gradient elution and/or resin crowding system.