104 results about "Thorium" patented technology

The invention relates to a crown ether covalent organic framework material as well as a preparation method and application thereof. The preparation method comprises the following steps: dissolving a crown ether monomer and an amino monomer in an o-dichlorobenzene solvent, adding a catalyst acetic acid aqueous solution, and uniformly dispersing to form a reaction solution; the method comprises the following steps: freezing a reaction solution through a liquid nitrogen bath, vacuumizing, filling nitrogen, carrying out a heating reaction, and carrying out post-treatment operations such as washing and drying on a reaction product, so as to obtain the crown ether covalent organic framework material BADT-DB18C6-COF. The crown ether covalent organic framework material is formed by condensation of a crown ether aldehyde monomer and an amino monomer, the crown ether monomer is 4, 4 ', 4' ', 4 '''-(6, 7, 9, 10, 17, 18, 20, 21-octahydrodibenzo [B, K] [1, 4, 7, 10, 13, 16] hexaoxacyclo octadecene-2, 3, 13, 14-tetrayl) tetrabenzaldehyde, and the crown ether monomer is 4, 4 ', 4' ', 4'''-(6, 7, 9, 10, 17, 18, 20, 21-octahydrodibenzo [B, K] [1, 4, 7, 10, 13, 16] hexaoxacyclo octadecene-2, 3, 13, 14-tetrayl) tetrabenzaldehyde. The amino monomer is 4 ', 5'-bis (4-aminophenyl)-[1, 1 ': 2', 1 ''-terphenyl]-4, 4''-diamine. The crown ether covalent organic framework material BADT-DB18C6-COF prepared by the invention is mainly used as an adsorbent, is used for adsorbing and recovering uranium, thorium and americium ions from a solution, shows good adsorption capacity on radionuclides U-238, Th-232 and Am-243, and is particularly suitable for the field of spent fuel post-treatment in the nuclear industry.

The invention belongs to the field of medical isotope separation and preparation, and particularly relates to a method for separating and purifying < 212 > Pb from a thorium solution, which comprises the following steps: 1) leacheate is introduced into a Pb selective adsorption column to pretreat the Pb selective adsorption column, and then < 232 > Th salt solution and leacheate are introduced in sequence; 2) continuously introducing a desorption solution into the Pb selective adsorption column, enabling the desorption solution passing through the Pb selective adsorption column to flow into the Th selective adsorption column, and collecting the outflowing desorption solution; a desorption solution only containing 212Pb is obtained; according to the method, the 212Pb in the high-concentration thorium solution can be separated and purified at the same time. While < 232 > Th impurity entrainment and pollution in a < 212 > Pb product are remarkably reduced, compared with a single-column process, the separation time is basically not increased. The separated 212Pb product has high radionuclide purity and chemical purity at the same time, and can meet related pharmaceutical requirements.

The invention relates to a method for machine learning aided design of a structural alloy for a fourth-generation thorium-based molten salt reactor, and belongs to the technical field of artificial intelligence auxiliary material design. The method comprises the steps that S1, an alloy component machine learning model for phase composition prediction is established, specifically, based on known alloy sample data, the sample data comprise alloy element content and corresponding phase composition information, and the machine learning model used for predicting alloy phase composition is established; s2, screening an initial alloy component space through phase composition constraint conditions; s3, secondary screening of alloy components based on thermodynamic simulation; s4, alloy sample preparation and solid solution homogenization treatment; s5, carrying out a mechanical property test; and S6, experimental result feedback and machine learning model closed-loop updating are carried out. According to the method, the artificial intelligence technology and the traditional alloy design theory are organically fused, an efficient and reliable new path is provided for research and development of key structural materials for the fourth-generation thorium-based molten salt reactor, and the important scientific research value and the engineering application prospect are achieved.

This invention discloses a Th / Ra generator containing natural thorium and its production. 224 The Ra method. The generator of this invention includes a cation exchange resin column and bottles I to VI; wherein bottle I is filled with the stock solution; bottle III is filled with deionized water; bottle IV is filled with 4.0–6.0 M nitric acid; bottles II, V, and VI are empty; bottle V is a specially designed collection bottle with an extraction resin column at its opening for collection. 224 Ra. The method of the present invention includes the following steps: 1) using a mixture containing 228 1) A natural thorium mixture of Th and Ra was concentrated to obtain a concentrate, and then the pH of the system was adjusted to serve as the packing stock solution for the Th / Ra generator; 2) The stock solution was passed through a cation exchange resin column to obtain a cation exchange resin column loaded with thorium. 224 Ra, and collect the eluent from the original solution for later use; 3) Elute the cation exchange resin column with inorganic acid. 224 Ra, then the eluent is collected using a special collection bottle to obtain... 224 Ra. This invention enables the separation, purification, and recycling of [product name]. 224 Ra, to overcome 228 Th / 224 The Ra generator has a stringent loading process to avoid the radioactive risks associated with handling tons of natural thorium.

The application relates to the technical field of quartz crystal purification, and particularly discloses a method for eliminating radioactive elements in quartz crystals, which comprises the following steps: adding quartz sand into a composite cleaning solution, stirring and cleaning, then performing solid-liquid separation and water washing to obtain pretreated quartz sand; performing heat treatment on the pretreated quartz sand in an oxygen-containing atmosphere at 850-1000 DEG C for 2-4 hours to obtain heat-treated quartz sand; rapidly cooling the heat-treated quartz sand in cooling water at 10-30 DEG C for 15-30 seconds, then crushing and screening to obtain crushed quartz sand; adding the crushed quartz sand into a selective acid cleaning solution under stirring to perform an acid cleaning reaction, then performing solid-liquid separation, washing and drying after the reaction to obtain low-radioactivity quartz sand. The composite cleaning solution and the selective acid cleaning solution are used in cooperation to efficiently remove radioactive elements such as uranium and thorium in the quartz crystals, and the physical and chemical properties of the quartz crystals can meet the requirements of high-end semiconductor and optical applications.

The application relates to a thorium and spallation element separation method, which comprises the following steps: injecting a thorium-based solution into column 1 to obtain a first effluent, washing column 1 with a first inorganic acid solution and a second inorganic acid solution in sequence to obtain a first washing solution and a first thorium solution respectively; injecting the first thorium solution into column 2 to obtain a second effluent, washing column 2 with a third inorganic acid solution and a second inorganic acid solution in sequence to obtain a second washing solution and a second thorium solution; mixing the first thorium solution and the second thorium solution, injecting into column 3 to obtain a third effluent, and washing column 3 with a fourth inorganic acid solution to obtain a third thorium solution. The method does not introduce other foreign reagents and is not polluted by foreign impurity ions, and the high ion potential of Th is utilized to preferentially adsorb on a cation column to achieve the purpose of separation from other spallation elements.

This invention relates to an aminophosphonate-functionalized carbon material, its preparation method, and its uses. The aminophosphonate-functionalized carbon material comprises a carbon matrix and a structure of Formula I covalently linked to the carbon matrix. It can be applied to capacitive deionization technology to selectively adsorb thorium from a mixed solution containing thorium and rare earth elements, exhibiting a high adsorption capacity for thorium.

This invention belongs to the field of uranium resource exploration technology, specifically relating to a method and apparatus for detecting gamma rays. The method includes: utilizing... 241 The equivalent peak position after the interaction of Am and NaI(Tl) crystals serves as a self-stabilizing peak, providing a stable gamma-ray reference peak and achieving automatic spectrum stabilization. A digital high-speed multichannel module acquires gamma-ray signals, achieving full acquisition of gamma-ray signals in the energy range of 30keV to 3000keV. Multiple Regions of Interest (ROIs) are set for the acquired gamma-ray signals using digital energy thresholds, obtaining CPS counts for the quantitative gamma energy range, the natural gamma energy range, and the uranium-thorium-potassium (UHT) energy range of the gamma spectrum. Using the calibration coefficients of each parameter in the standard model, and based on the CPS counts for the quantitative gamma energy range, the natural gamma energy range, and the UHT / UHT energy range of the gamma spectrum, the quantitative gamma, natural gamma, and gamma spectrum detection results are output. This invention enables a single probe to simultaneously output measured data for quantitative gamma, natural gamma, and gamma spectra, improving the efficiency of acquiring these data.

The invention relates to wet preparation of a radiation therapy source and a method for accumulating radium radionuclides. The method comprises providing a first solution comprising a thorium radionuclide and a thorium binding extractant, wherein the first solution does not bind to radium; allowing a portion of the thorium radionuclides in the first solution to decay to radium atoms; and collecting radium atoms resulting from the decay. The collected radium atoms may be contained in a solution into which a brachytherapy source is immersed in a manner that collects radium atoms onto the brachytherapy source.

The present application relates to a kind of carbonate lithology identification method based on well logging parameter, device and storage medium, belong to rock type identification technical field, the method includes: the multiple carbonate thin section of target formation is calibrated, obtains the well logging parameter and type of corresponding depth of carbonate thin section;Carbonate thin section includes dolomite thin section and limestone thin section;Based on the well logging parameter of corresponding depth of carbonate thin section plot crossplot, and determine target parameter according to crossplot and type;Target parameter includes uranium value, thorium value, acoustic time difference and compensation neutron;Based on target parameter, the lithology of dolomite and limestone in non-coring section is identified.The present application provides the carbonate lithology identification method based on well logging parameter, is analyzed with multiple parameters such as uranium, thorium, acoustic time difference and compensation neutron, realizes accurate identification to carbonate lithology.

The invention discloses a method for extracting and separating rare earth, iron and uranium in monazite excellent molten slag, which comprises the following steps: step 1, a hydrochloric acid complete dissolution step: realizing preliminary release of valuable elements in the monazite excellent molten slag; 2, oxalic acid precipitation, wherein specific separation and solution purification of thorium are achieved; 3, primary uranium extraction is conducted, and preliminary separation of rare earth elements and uranium iron is achieved; step 4, a rare earth recovery step; 5, back extraction is carried out, and preliminary enrichment of uranium and iron is achieved; 6, secondary extraction of uranium to realize uranium-iron separation; step 7, iron precipitation; step 8, uranium back extraction; and 9, uranium product forming. The method aims at achieving step-by-step extraction and separation of rare earth, iron and uranium in the leaching solution of the optimal dissolving slag, the problem that uranium and iron are difficult to separate in the existing extraction process is solved, and the recovery rate of valuable elements of rare earth and uranium is increased.

The invention relates to the technical field of metal target material preparation, and discloses a cylindrical metal thorium target material preparation method, which comprises: taking metal thorium powder, placing into a cylindrical mold, carrying out static pressure molding, and demolding to obtain a metal thorium blank; taking a plurality of metal thorium plain blanks, stacking the metal thorium plain blanks in a cylindrical crucible, placing the cylindrical crucible in smelting equipment, vacuumizing to a negative pressure state, then heating for smelting, after the metal thorium plain blanks are completely molten, filling inert gas until the interior of the smelting equipment is in a positive pressure state, stopping smelting, and after the smelting equipment is cooled to the room temperature, taking out the metal thorium plain blanks; taking out a cylindrical metal thorium target material crude product; and the cylindrical metal thorium target material crude product is machined, and the cylindrical metal thorium target material is obtained. The method has the following technical effects that the multiple metal thorium plain blanks are stacked in the cylindrical crucible to be smelted, and the problems that the upper and lower compactness of the metal thorium plain blanks is inconsistent, and demolding is difficult can be solved. Inert gas is filled in the smelting process, so that air holes in the metal thorium target material can be eliminated, and the compactness is improved.

The invention discloses a monazite smelting laboratory wastewater treatment method, which comprises: 1, controlling the temperature of laboratory wastewater at 30-90 DEG C, adding an alkali cake, carrying out a stirring reaction for 0.5-2 h, and after the reaction is completed, carrying out solid-liquid separation to obtain a phosphorus removal wastewater filtrate and a phosphorus-rare earth co-precipitation filter residue; 2, the filtrate in the step 1 is subjected to adsorption treatment through a silica gel adsorption column, adsorption tail liquid is obtained, and the total amount of thorium and uranium in the adsorption tail liquid is reduced to 0.3 ppm or below; and step 3, transferring the adsorption tail liquid into an ozone column, filling the ozone column with a silicon-aluminum compound catalyst material, and continuously introducing ozone into the ozone column through an ozone generator so as to reduce the COD value in the adsorption tail liquid to below 50ppm through ozone oxidation, thereby finally obtaining qualified treated liquid. The invention aims to reduce laboratory wastewater radionuclides, namely uranium, thorium, phosphorus and COD (Chemical Oxygen Demand).

The invention discloses a carboxyl-functionalized metal organic framework material and preparation and application thereof in treatment of thorium-containing wastewater, and the method comprises the following steps: adding MIL-101-Cl and amino acid into an organic solvent, carrying out ultrasonic dispersion, adding triethylamine, and stirring; reacting at 100 DEG C, centrifuging, washing, and carrying out vacuum drying at 50-70 DEG C; the MIL-101-Cl is prepared by carrying out a reaction on MIL-101 powder, paraformaldehyde, tin tetrachloride and trimethylchlorosilane in anhydrous dichloromethane. The problems that in the prior art, the structure is disordered, stability is poor, selectivity is lost, and industrialization is difficult are solved. According to the invention, a carboxyl donor is grafted on the surface of chloromethylated MIL-101, and meanwhile, the increase of the carboxyl content obviously enhances the adsorption capacity of the material; due to the increase of the carboxyl density, the MIL-101-2COOH has more excellent Th (IV) adsorption selectivity and chemical stability.

The invention discloses a method for recovering uranium and rare earth from superior dissolving slag, which comprises the following steps: step 1, mixing the superior dissolving slag of monazite with a hydrochloric acid solution for acid leaching, and filtering to obtain leached filtrate and a filter cake; 2, sodium chloride is added into the leaching filtrate, so that the chloride ion concentration reaches 140-150 g / L, and an adsorption stock solution is obtained; 3, the adsorption stock solution is subjected to uranium adsorption operation through strongly basic anion resin until the resin is saturated, and saturated resin and adsorption tail liquid are obtained; 4, the saturated resin is washed, leached, subjected to impurity removal and precipitated, and sodium diuranate is obtained; 5, oxalic acid is added into the adsorption tail liquid to precipitate thorium, and thorium oxalate precipitate and filtrate after thorium precipitation are obtained after solid-liquid separation; and step 6, carrying out rare earth precipitation on part of the filtrate after thorium precipitation in the step 5 to obtain a rare earth product. The invention aims to convert traditional'wastewater 'into valuable resources through internal circulation and recycling.

Thorium-based fuel bundles are used in existing PHWR reactors (e.g., Indian 220 MWe PHWR, Indian 540 MWe PHWR, Indian 700 MWe PHWR, CANDU 300 / 600 / 900) in place of conventional uranium-based fuel bundles, with little or no modifications to the reactor. The fuel composition of such bundles is 60+ wt % thorium, with the balance of fuel provided by low-enriched uranium (LEU), which has been enriched to 13-19.95% 235U. According to various embodiments, the use of such thorium-based fuel bundles provides (1) 100% of the nominal power over the entire life cycle of the core, (2) high burnup, and (3) non-proliferative spent fuel bundles having a total isotopic uranium concentration of less than 12 wt%. Reprocessing of spent fuel bundles is also avoided.

The application relates to a sandstone type uranium ore enrichment zone determination method and device and a storage medium. The method comprises the following steps: obtaining the thorium element content in a spectral logging; calculating the uranium element content according to the thorium element content; calculating a sedimentary environment factor; calculating a clay mineral relative content factor; calculating a argillaceous content factor; calculating an organic matter content factor curve; calculating a ore-controlling comprehensive evaluation parameter; and determining a uranium abnormal enrichment section. The sandstone type uranium ore enrichment zone determination method, device and storage medium provided by the embodiment of the application can effectively calculate the ore body enrichment depth, thereby reducing the exploration cost, improving the exploration success rate, and being applicable to new area exploration, and having high popularization and application value.

The invention discloses a thorium-doped strontium tetraborate crystal as well as a preparation method and application thereof, the chemical formula of the thorium-doped strontium tetraborate crystal is ThxSr1-xB4 + yO7 (Th SBO), and the thorium-doped strontium tetraborate crystal grows by adopting a solution method. The Th: SBO crystal disclosed by the invention is low in melting point, simple in component and beneficial to realizing high-quality crystal growth; the material has a wide band gap, has high transmittance in a vacuum ultraviolet band, is beneficial to reduction of absorption loss in a nuclear transition luminescence band, and is beneficial to excitation and detection of a nuclear transition signal; the SBO crystal is a random quasi-phase matching (RQPM) nonlinear optical crystal, 296.76 nm narrow linewidth laser 148.38 nm frequency doubling light can be used as an excitation source of the nuclear light clock through frequency doubling, and a Th host crystal and a frequency doubling crystal are combined, so that the complexity of a system is remarkably simplified, and a core material is provided for miniaturization of the nuclear light clock.

The invention relates to the technical field of metal target material preparation, and discloses a preparation method of a high-compactness metal thorium target material, which comprises the following steps: taking metal thorium powder, grinding and refining, and sieving with a screen twice to obtain metal thorium fine powder; transferring the metal thorium fine powder into a mold for static pressure molding, and demolding to obtain a metal thorium blank; the metal thorium blank is placed between two inert material gaskets and placed in a sintering container, vacuum sintering is conducted in vacuum sintering equipment, and after sintering is completed, a crude product of the metal thorium target material is taken out after the vacuum sintering equipment is cooled to the room temperature; and the crude product of the metal thorium target material is machined through a grinding machine, a surface oxidation layer is removed, and the metal thorium target material is obtained. The method has the following technical effects that the fineness and uniformity of the metal thorium powder are improved through grinding refining and twice sieving, the forming capacity of the metal thorium powder is enhanced, and abnormal growth of crystal grains in the sintering process is avoided; and the inert material gasket is arranged to participate in sintering, so that sintering warping caused by non-uniform grain shrinkage is avoided.

The application discloses a high-thorium sandstone reservoir logging identification method, device and equipment and a readable storage medium. Uranium-free gamma measurement values and potassium content in a to-be-identified high-thorium sandstone reservoir are acquired, and acoustic travel time and density of the to-be-identified high-thorium sandstone reservoir are acquired. The potassium content and the uranium-free gamma measurement values are used to construct a uranium-free gamma curve without thorium influence, the uranium-free gamma curve without thorium influence is compared with a measured uranium-free gamma curve, and a high-thorium layer section is qualitatively identified in a sandstone profile and a mudstone profile. In the high-thorium layer section, the uranium-free gamma curve without thorium influence is used to quantitatively calculate shale content. According to the shale content, the acoustic travel time and the density, shale influence is eliminated, and porosity of the to-be-identified high-thorium sandstone reservoir is calculated. According to the shale content and the porosity, a reservoir is identified and divided in the high-thorium layer section, and logging identification of the to-be-identified high-thorium sandstone reservoir is completed. The application improves the calculation precision of reservoir mineral components and physical property parameters.

The invention discloses a method for synchronously measuring the concentration of uranium and thorium in adsorption tail liquid, and belongs to the technical field of analysis and testing. The method for synchronously measuring the concentrations of uranium and thorium in the adsorption tail liquid comprises the following steps: mixing tail liquid to be measured, arsenazo III and a first acid solution to obtain a mixed solution I; under a preset wavelength, carrying out absorbance determination on the mixed solution I by adopting a spectrophotometric method to obtain first absorbance; mixing the mixed solution with a second acid solution to obtain a mixed solution I; under a preset wavelength, carrying out absorbance determination on the mixed solution I by adopting a spectrophotometric method to obtain second absorbance; determining the thorium concentration in the tail liquid to be detected according to the second absorbance; and determining the uranium concentration in the tail liquid to be detected according to the difference between the first absorbance and the second absorbance. The spectrophotometric method is adopted to measure the absorbance of the to-be-measured tail liquid, the concentration of uranium and thorium ions is measured at the same time, the testing precision is high, and operation is easy and convenient.

Systems and methods for generating radionuclides, such as radium-224. Systems herein may include a first cartridge having a first opening, a second opening, and a chamber therebetween having a first resin having affinity for thorium-228 and bismuth-212; a second cartridge having a first opening, a second opening, and a chamber therebetween having a second resin having affinity for thorium-228 and bismuth-212, a third cartridge having a first opening, a second opening, and a chamber therebetween comprising a third resin having affinity for thorium-228 and bismuth-212, a fourth cartridge having a first opening, a second opening, and a chamber therebetween having a third resin having affinity for lead-212; wherein a continuous flow path is formed from a top of the first cartridge though the second cartridge, through the third cartridge, and to a bottom of the fourth cartridge during system use.

The invention relates to a comprehensive recovery method for valuable metals in zirconium crystallization mother liquor. The method comprises the following steps: S1) separating and enriching iron and uranium; s2) separating and enriching scandium; s3) enriching zirconium, hafnium, titanium and thorium; and S4) separating and enriching rare earth. According to the method, radioactive pollution of the zirconium crystallization mother liquor is reduced, classified recycling of uranium and thorium is achieved by optimizing the recycling process sequence, and the amount of radioactive waste residues is greatly reduced; and meanwhile, scandium and high-purity rare earth are efficiently recovered, and the resource channel is widened, so that the problems of associated resource waste and radioactive pollution are solved, full-process recovery of valuable metals is realized, and the economic and environmental benefits of the zirconium crystallization mother liquor are remarkably improved.

This invention belongs to the fields of chemical metallurgy and environmental protection technology, specifically relating to a method for recovering ferrophosphate and simultaneously removing thorium from rare earth waste residue, and a ferrophosphate product. The method targets rare earth waste residue containing insoluble ferrophosphate. After grinding pretreatment, it undergoes enhanced acid hydrolysis at 75-85°C using 70-80% sulfuric acid. The high concentration of protons disrupts pyrophosphate bonds, achieving efficient leaching of phosphorus and iron while inhibiting the dissolution of calcium impurities. The strongly acidic filtrate after solid-liquid separation is subjected to multi-stage extraction using a primary amine extractant (N1923) to selectively remove radioactive thorium. The raffinate is then pH-controlled to induce the synthesis of battery-grade ferrophosphate. This invention achieves a phosphorus recovery rate >92% and a thorium removal rate >99.5%, not only solving the environmental pollution problem caused by rare earth waste residue storage but also preparing a high-value-added lithium battery cathode material precursor.

The invention belongs to the field of geophysical prospecting, and particularly relates to an identification method, system and equipment for a stratum brine potassium salt enrichment layer and a medium. The method comprises the following steps: comparing stratum brine layer identification results obtained by different methods, and determining a stratum with overlapped brine layer identification results as a final stratum brine layer; identifying a potassium-rich brine layer by using a natural gamma-ray spectrum logging potassium element content curve; calculating the shale content of the framework of the potassium-rich brine layer through the thorium curve so as to obtain the content of the potassium element in the potassium-rich brine; and determining the brine potassium salt enrichment layer according to the potassium element content in the potassium-rich brine. According to the method, the brine reservoir identification accuracy is greatly improved.

A device, comprising a 229Th-containing material; a source of coherent radiation configured to illuminate the 229Th-containing material; and a detector configured to detect a 229mTh ↔ 229Th nuclear transition.

The application provides a method for preparing thorium sulfate by using monazite optimal dissolution residue, and relates to the technical field of hydrometallurgy. The monazite optimal dissolution residue is subjected to leaching, and the leaching rates of uranium, thorium and rare earth are high, so that leaching ore slurry is obtained. The leaching ore slurry is mixed with a polyacrylamide solution, and solid-liquid separation is carried out, so that a primary liquid is obtained. The primary liquid is subjected to first solvent extraction, iron is removed at the same time of recovering uranium, and a thorium-containing raffinate is obtained. The thorium-containing raffinate is subjected to second solvent extraction, thorium and rare earth are efficiently separated, and thorium-loaded organic phase and a rare earth-containing raffinate are obtained. The thorium-loaded organic phase is subjected to crystallization back extraction, and thorium sulfate is obtained. The method provided by the application is simple in operation, good in separation effect of uranium, thorium and rare earth, high in product purity, continuous in operation, and suitable for industrial application. The results of examples show that the purity of the thorium sulfate prepared by the application is greater than or equal to 98wt%.

The present application relates to the nuclear technology field, specifically to a method for separating thorium from a thorium and lanthanum mixture. The method comprises the following steps: in a three-electrode system, pulse constant current controlled potential electrolysis is performed on a molten salt system containing mixed ions of thorium and lanthanum series elements, and the deposition rate difference of thorium and lanthanum series element ions during pulse constant current electrolysis and the electrolytic reaction limitation of the control potential on the lanthanum series element ions are utilized to achieve efficient separation of thorium from the thorium and lanthanum mixture. The molten salt system containing mixed ions of thorium and lanthanum series elements is obtained by adding the thorium and lanthanum mixture into a chloride molten salt, mixing uniformly, and passing in chlorine gas mixture to chlorinate the mixture and dissolve it into the chloride molten salt. The method has the advantages of simple process, strong radiation resistance, no additional radioactive waste, and low cost, and is suitable for industrial application of molten salt reactor spent fuel reprocessing.

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; andd) 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 invention belongs to the technical field of nuclear fuel cycle analysis, and relates to a pretreatment process for step-by-step separation of thorium, uranium, americium and plutonium in neptunium dioxide powder, and the process comprises seven steps of sample dissolution, sample valence adjustment, Th separation, U separation, Am separation, Pu separation and content determination. According to the method, the TEEVA, UTEEVA and TRU extraction chromatography resin coupling technology is applied, and step-by-step separation of Th, U, Am and Pu in neptunium dioxide powder is achieved; measuring the content of the separated trace actinide elements by using an inductively coupled plasma mass spectrometer (ICP-MS); through the step-by-step separation pretreatment process, the adding standard recovery rate of each element of Th, U, Am and Pu is greater than 90%, and the precision of the method is superior to 10%.