Methods and systems for recovering or extracting rare earth elements under mild conditions include subjecting a material including rare earth element to a rare earth element crystallization medium under solvothermal conditions sufficient to form rare earth element crystals capable of gravity separation and purification.

A method of recycling Ni and/or Co from a functional material such as a battery or catalyst material, the method comprising: forming an acidic aqueous recycling feed of the functional material by acid leaching the functional material or a derivative thereof, the acidic aqueous recycling feed comprising Ni and/or Co in solution; contacting the acidic aqueous recycling feed with an organic solvent extraction composition; and extracting one or both of Ni and Co from the acidic aqueous recycling feed into the organic solvent extraction composition, wherein the organic solvent extraction composition comprises: an organic solvent which is immiscible with the acidic aqueous recycling feed; a picolinic acid ester or picolinic acid amide which is soluble in the organic solvent; and a phase transfer catalyst.

A method of recycling Ni and/or Co from a functional material such as a battery or catalyst material, the method comprising: forming an acidic aqueous recycling feed of the functional material by acid leaching the functional material or a derivative thereof, the acidic aqueous recycling feed comprising Ni and/or Co in solution; contacting the acidic aqueous recycling feed with an organic solvent extraction composition; and extracting one or both of Ni and Co from the acidic aqueous recycling feed into the organic solvent extraction composition, wherein the organic solvent extraction composition comprises: an organic solvent which is immiscible with the acidic aqueous recycling feed; a picolinic acid ester or picolinic acid amide which is soluble in the organic solvent; and a phase transfer catalyst.

A method for extracting metals from the black mass of lithium-ion batteries, the black mass containing the anode and cathode materials of the batteries, wherein the cathode material comprises lithium, nickel, and cobalt. The method is carried out by an arrangement that is suitable for use in the method.

Novel dissymmetric N,N-dialkylamides which meet the following formula (I):

##STR00001##

where R represents a linear or branched alkyl group at C.sub.8 to C.sub.15. A method for synthesizing these N,N-dialkylamides, and to the uses of same as extractants, alone or in admixture, in order to extract uranium and/or plutonium from an aqueous acid solution, or to totally or separate uranium from plutonium from an aqueous acid solution and, in particular, an aqueous solution resulting from dissolving spent nuclear fuel in nitric acid. Further, a method for processing an aqueous solution resulting from the dissolution of a spent nuclear fuel in nitric acid, allowing the uranium and plutonium contained in the solution to be extracted, separated and decontaminated in a single cycle, without requiring any plutonium reduction operation, and in which one of the aforementioned N,N-dialkylamides or a mixture of same is used as extractant. Applications for the method include the processing of spent nuclear fuels, in particular comprising uranium (e.g. UOX) or uranium and plutonium (e.g. MOX).

Novel dissymmetric N,N-dialkylamides which meet the following formula (I):

##STR00001##

where R represents a linear or branched alkyl group at C.sub.8 to C.sub.15. A method for synthesizing these N,N-dialkylamides, and to the uses of same as extractants, alone or in admixture, in order to extract uranium and/or plutonium from an aqueous acid solution, or to totally or separate uranium from plutonium from an aqueous acid solution and, in particular, an aqueous solution resulting from dissolving spent nuclear fuel in nitric acid. Further, a method for processing an aqueous solution resulting from the dissolution of a spent nuclear fuel in nitric acid, allowing the uranium and plutonium contained in the solution to be extracted, separated and decontaminated in a single cycle, without requiring any plutonium reduction operation, and in which one of the aforementioned N,N-dialkylamides or a mixture of same is used as extractant. Applications for the method include the processing of spent nuclear fuels, in particular comprising uranium (e.g. UOX) or uranium and plutonium (e.g. MOX).

A method for the treatment of an aqueous solution resulting from the dissolution of a spent nuclear fuel in nitric acid, allowing the uranium and plutonium contained in the solution to be extracted, separated and decontaminated in a single cycle, without requiring any operation involving a reductive stripping of plutonium. Applications for the method include the processing of uranium-based and/or plutonium-based spent nuclear fuels.

A method for the treatment of an aqueous solution resulting from the dissolution of a spent nuclear fuel in nitric acid, allowing the uranium and plutonium contained in the solution to be extracted, separated and decontaminated in a single cycle, without requiring any operation involving a reductive stripping of plutonium. Applications for the method include the processing of uranium-based and/or plutonium-based spent nuclear fuels.

Provided are: an extractant which is capable of quickly and highly efficiently extracting zirconium from an acidic solution that is obtained by acid leaching a material containing zirconium and scandium such as an SOFC electrode material; and a method for extracting zirconium, which uses this extractant. A zirconium extractant according to the present invention is composed of an amide derivative represented by general formula (I). In the formula, R1 and R2 respectively represent the same or different alkyl groups, each of which may be linear or branched; R3 represents a hydrogen atom or an alkyl group; and R4 represents a hydrogen atom or an arbitrary group other than an amino group, said arbitrary group being bonded, as an amino acid, to the carbon.

A method for selectively extracting sedimentogenic strontium and barium from terrigenous elastic sediments to reflect the difference between marine and continental sedimentary environments is disclosed. The method comprises collecting loose sediment, removing visible biogenic clasts, baking the sample and crushing the sample to a grain size no larger than 100-mesh. The method further comprises weighing the sample, reacting the sample in acetic acid or acetic acid-acetate solution, stirring or oscillating the sample at room temperature and normal pressure, separating the solid and liquid after reaction and analyzing strontium and barium in the supernatant. The gained Sr/Ba ratio of the supernatant reflects whether the sediments were deposited in a marine or a continental sedimentary environment.