80results about "Uranium oxides/hydroxides" patented technology

The invention relates to a process for reprocessing a spent nuclear fuel and for preparing a mixed uranium-plutonium oxide, which process comprises: a) the separation of the uranium and plutonium from the fission products, the americium and the curium that are present in an aqueous nitric solution resulting from the dissolution of the fuel in nitric acid, this step including at least one operation of coextracting the uranium and plutonium from said solution by a solvent phase; b) the partition of the coextracted uranium and plutonium to a first aqueous phase containing plutonium and uranium, and a second aqueous phase containing uranium but no plutonium; c) the purification of the plutonium and uranium that are present in the first aqueous phase; and d) a step of coconverting the plutonium and uranium to a mixed uranium/plutonium oxide. Applications: reprocessing of nuclear fuels based on uranium oxide or on mixed uranium-plutonium oxide.

A process for the extraction of uranium compounds from wet-process phosphoric acid includes lowering the iron concentration of the wet-process phosphoric acid and reducing the valency of any remaining ferric iron in the wet-process phosphoric acid to ferrous iron, and then extracting uranium compounds from the wet-process phosphoric acid. The process can include separating a side stream from a feed stream of wet-process phosphoric acid, wherein the side stream has a greater concentration of the uranium compounds than the feed stream by filtration. Extracting uranium compounds from the wet-process phosphoric acid can be by ion exchange process or by solvent extraction.

A method for making a metal-titania pulp and photocatalyst is provided, including firstly acidically hydrolyzing a titanium alkoxide solution in presence of an alcohol solvent to get a colloidal solution; then, adding at least one metal salt solution into the colloidal solution to produce a nano-porous metal/titania photocatalyst under appropriate conditions by appropriate reaction. The nano-porous metal/titania photocatalyst thus prepared has excellent optical activity and is applicable in research of water decomposition with light to improve production efficiency of hydrogen energy. In addition, the photocatalyst is further processed in the form of powder or film to facilitate industrial application in wastewater treatment.

A method of declogging at least one filter of a plant for manufacturing uranium oxide from uranium hexafluoride, including separating, from the wall of the filter, uranium oxyfluoride particles deposited, by a stream of inert gas such as nitrogen, injected into the filter, in a counter-currentwise direction to the flow of hydrofluoric acid.

Utilization of process and equipment for oxidation of metal sulfides, preferably two step metal sulfide oxidation reactions, and more preferably with looping back of second step oxide to the first step as an oxidizing agent, to generate sulfur dioxide and a useful metal or metal oxide, and react the sulfur dioxide with halogen (iodine or bromine) and water to produce sulfuric and halogen acid under moderate process conditions and equipment requirements and then dissociating the halogen acids (HI or HBr) to halogen and hydrogen as an overall environmentally and cost efficient and otherwise acceptable safe process for producing hydrogen and other useful products.

A method for reprocessing spent nuclear fuel from a light water reactor includes the step of reacting spent nuclear fuel in a voloxidation vessel with an oxidizing gas having nitrogen dioxide and oxygen for a period sufficient to generate a solid oxidation product of the spent nuclear fuel. The reacting step includes the step of reacting, in a first zone of the voloxidation vessel, spent nuclear fuel with the oxidizing gas at a temperature ranging from 200-450° C. to form an oxidized reaction product, and regenerating nitrogen dioxide, in a second zone of the voloxidation vessel, by reacting oxidizing gas comprising nitrogen monoxide and oxygen at a temperature ranging from 0-80° C. The first zone and the second zone can be separate. A voloxidation system is also disclosed.

The invention relates to a method for producing triuranium octoxide by microwave calcination of ammonium diuranate, comprising the steps: evenly mixing ammonium diuranate and triuranium octoxide by weight percent of (10 to 2): 1 to obtain a mixed material; then putting the mixed material into a microwave reactor; regulating microwave output power to be 10 to 80 kW; room temperature of the material is raised to 350 DEG C to 800 DEG C at the rate of 20 to 100 DEG C/min; keeping the temperature for 10 to 40 min; and obtaining a triuranium octoxide product. In the method, a calcination product with strong wave absorbing performance is added to a calcination raw material with relatively weak wave absorbing performance; the microwave calcination of substances with weak wave absorbing performance is realized; and moreover, the method has short production period, low energy consumption and easy industrial application.

The invention relates to a method for preparing an orientated tungsten oxide nano film. The method takes an ethanol suspension of monocrystal tungsten trioxide (WO3) nano-plates as a precursor, and utilizes the habit that the nano-plate with high diameter-thickness ratio tends to be parallel to a substrate and the principle that solvent volatilization causes the oriented self-assembly of the nano-plate to prepare the tungsten oxide (WO3) nano film which is formed by overlapping the tungsten trioxide (WO3) nano-plates and oriented along the [002] crystallographic direction. The method is completed at a room temperature, and does not require subsequent heating treatment; and the tungsten trioxide (WO3) nano film prepared is strongly oriented along the [002] crystallographic direction, namely the WO3 nano film is spread along an ab plane and a c- shaft is the film thickness direction. The method has the characteristics of simple technological process, convenient operation, low requirements on equipment conditions and strong adaptability; and WO3 nano film materials have the characteristics of high crystallinity and good orientation.

The invention discloses a process for preparing UO3 through uranyl nitrate air-blast atomization dry pyrolysis denitration. According to the process, a designed and processed combustion chamber and a denitration reactor are adopted as main body equipment of uranyl nitrate pyrolysis denitration, a high-temperature high-speed gas generated from combustion of propane and excessive air is adopted as a heat source and an atomization gas source, and a uranyl nitrate liquid is subjected to drying dehydration and pyrolysis denitration. The process has the advantages of being short in process procedure, simple in equipment structure, stable in operation and high in UNH (Uranyl-Nitrate Hexahydrate) conversion rate, the prepared UO3 is uniform in granularity distribution and good in chemical reaction activity, and the like.

The invention discloses an uranium oxide micro-sphere and a preparation method, a porous structure is provided in the uranium oxide micro-sphere, and the porous structure is composed of nano particles. The invention also comprises a preparation method of the uranium oxide micro-sphere, which comprises the following steps: 1)performing a hydro-thermal reaction on a mixing aqueous solution to obtain a sea urchin-state uranium-containing micro-sphere precursor, wherein the mixing aqueous solution comprises a uranyl nitrate aqueous solution, glycerol and urea; 3)washing and drying the uranium-containing micro-sphere precursor; and 3)placing the dried uranium-containing micro-sphere precursor in a tubular furnace for pyrolysis to obtain the uranium oxide micro-sphere. The preparation method has the advantages of simple process and easy control, and the prepared uranium oxide micro-sphere has the characteristics of small size and has porous structure, and has latent application value in the relative fields of catalysis and nuclear energy.

The invention discloses a method for producing uranium trioxide by heating uranyl nitrate solution in a microwave manner. The method comprises the following steps: delivering the uranyl nitrate solution as a raw material; and carrying out explosive evaporation of the uranyl nitrate solution, concentrating, decomposing uranyl nitrate to remove nitrate, stopping micro-wave heating,, placing materials in a muffle furnace, and ball-milling to obtain powder so as to obtain uranium trioxide powder. In the concentrating process, the temperature is controlled by adjusting micro-wave power, and the solution is prevented from splashing and overflowing; in a nitrate removing process, the temperature and the heating time are controlled, and the circumstance that triuranium octaoxide is generated due to over-high temperature is avoided; nitrate removing products are stable in a muffle furnace at the temperature of 350 DEG C, and the uranium trioxide conversion rate reaches 100%. By the method of ball-milling to obtain the powder, the powdery uranium trioxide is prepared, meanwhile, materials adhered to walls can be ground, and therefore, the retention amount of the materials in a container is reduced.

The invention belongs to the technical field of preparation of uranium trioxide, and particularly relates to a method of preparing high-activity uranium trioxide by thermal denitration of uranyl nitrate. The method comprises the following steps: step (1) evaporating and concentrating an uranyl nitrate solution to obtain a concentrated uranyl nitrate solution; step (2) conveying the concentrated uranyl nitrate solution to a cooling crystallizer, cooling the concentrated uranyl nitrate solution to a temperature below 40 DEG C, carrying out cooling crystallization to form UO2(NO3)2.6H2O crystals,and returning a saturated solution to an evaporation and concentration device in step (1); step (3) dehydrating the UO2(NO3)2.6H2O crystals obtained in step (2) by microwave drying, and converting the UO2(NO3)2.6H2O crystals obtained in step (3) into UO2(NO3)2 powder; and step (4) generating the UO3 product in a fixed bed by using the UO2(NO3)2 powder obtained in step (3) in a vacuum environmentthrough microwave heating. The method has the advantages of short technological process, no generation of radioactive ammonia-nitrogen wastewater, good product activity and the like, increases the integral level of a uranium purification and conversion technology in the nuclear fuel cycle, and has obvious social and economic benefits.

The object of the present invention is to provide a feedstock liquid, from which fuel kernels with good quality can be produced, and a method of preparing the feedstock liquid. The present invention provides a feedstock liquid with a viscosity from 4.0×10⁻² to 6.5×10⁻² Pa·s at 15° C., for the production of ammonium diuranate particles. The present invention also provides a method of preparing a feedstock liquid used for the production of ammonium diuranate particles, which includes mixing a uranyl nitrate solution and tetrahydrofurfuryl alcohol to produce a uranyl nitrate mixture, dissolving polyvinyl alcohol in water to produce an aqueous polyvinyl alcohol solution, mixing the aqueous polyvinyl alcohol solution with tetrahydrofurfuryl alcohol to produce a polyvinyl alcohol solution, and mixing the uranyl nitrate mixture with the polyvinyl alcohol solution.

The invention discloses a method for producing triuranium octoxide by calcining ammonium uranyl tricarbonate with microwaves, which comprises the following steps: putting ammonium uranyl tricarbonate into a microwave reactor, turning on a microwave heating switch, adjusting the microwave output power to 5-60kW, heating the materials to 400-700 DEG C from room temperature at the speed of 20-100 DEG C/minute, preserving heat for 5-30 minutes, and then naturally cooling to the room temperature to acquire a triuranium octoxide product. The production method has low energy consumption as well as uniform product ingredients and granularity, and the calcining time in the whole technical process is only one third of a conventional method.

The invention belonging to the technical field of nuclear fuel circulation, and particularly relates to a method for preparing triuranium octaoxide from uranium hexafluoride. The method comprises the following three steps: step 1, preparation of a UO2F2 hydrolysate; step 2, preparation of UO2F2 powder; step 3, roasting for preparation of U3O8. According to the method, the process of preparing U3O8 through conventional UF6 reduction is shortened, and the addition of ammonia water in the process is avoided, so ammonia nitrogen wastewater generated in the process is reduced, a preparation process is simple, cost is low, and industrialization is easy to realize. According to the method, a large amount of fluorine in UF6 is converted into HF acid through water, the HF acid reacts with potassium hydroxide to finally prepare a byproduct potassium hydrogen fluoride, and the byproduct potassium hydrogen fluoride can be returned to an electrolytic fluorine production unit in a uranium conversion system so as to realize recycling. The U3O8 prepared by the method is more uniform in granularity, good in powder flowability, low in radioactivity, low in fluorine content and convenient for long-term stable storage.

A method for converting UO₃ and/or U₃O₈ into hydrated UO₄ of formula UO₄.nH₂O wherein n is 2 or 4, comprising the following successive steps:

• • a) preparing an aqueous suspension of a UO₃ powder and/or a U₃O₈ powder;
  • b) adding hydrogen peroxide H₂O₂ to the aqueous suspension of a UO₃ and/or U₃O₈ powder, converting the UO₃ and/or U₃O₈ into hydrated UO₄ and precipitating, crystallizing the hydrated UO₄ in the suspension;
  • g) recovering the precipitate, crystals of UO₄ hydrate;
  • h) optionally, washing the recovered UO₄ hydrate precipitate, crystal(s);
  • i) optionally, repeating step d);
  • j) optionally, drying the precipitate, the crystals;

wherein the addition of H₂O₂ to the aqueous suspension is carried out so that the suspension contains a stoichiometric excess of H₂O₂ relatively to the stoichiometry of the reaction from UO₃:

UO₃+nH₂O+H₂O₂→UO₄.nH₂O+H₂O  (1)

or of the reaction from U₃O₈

UO_2.67+1.33H₂O₂+nH₂O→UO₄.nH₂O+H₂O  (2)

• • and the pH of the suspension is maintained in steps a) and b) at a value comprised between 2 and 3.

The invention relates to a treatment method of superior molten slag of monazite. Specifically, the treatment method is a method for extracting and separating iron, uranium, thorium and mischmetal in the superior molten slag of the monazite in a mixed acid solution of hydrochloric acid and nitric acid, and comprises the following steps : thermally dissolving the superior molten slag using hydrochloric acid; separating iron, uranium-thorium and rare earth; separating iron and uranium; preparing mixed feed liquor of hydrochloric acid and nitric acid for thorium and rare earth; separating thoriumand rare earth; and extracting mischmetal. The treatment method is good in uranium, thorium and rare earth separation effect and high in recovery rate, uranium and thorium products meeting nuclear fuel requirements can be produced, cyclic utilization of acid can be achieved, and the treatment method is environmentally friendly.

The invention belongs to the technical field of uranium ore hydrometallurgy, and particularly relates to a method for preparing U3O8 from a uranium-containing sodium carbonate solution, which comprises the following steps: step 1, adsorbing a sodium carbonate system by using high-capacity resin; step 2, leaching non-crystalline ammonium bicarbonate; 3, carrying out double-part crystallization; step 4, performing ammonia distillation circulation technology; by adopting the technical process, the qualified U3O8 product is prepared. PH adjustment is adopted, so that the resin adsorption capacityis improved, the uranium concentration is improved, and the ammonia distillation treatment capacity is reduced; by adopting the recommended process parameters and equipment, the problems of bed blockage and pipeline blockage in the ammonium bicarbonate leaching process are avoided. A double-part crystallization process is adopted, so that the crystallization efficiency is improved, the crystal form is good, and the crystallization and impurity removal effects are improved. By adopting the process, ammonia-free and chlorine-free emission is realized, and ammonia is completely circulated.