Method of processing the uranium- and fluorine-containing wastes
FIELD: technology of processing uranium-and fluorine-containing wastes.
SUBSTANCE: proposed method includes preparation of solutions from wastes, concentration of solutions by sedimentation of uranium followed by dissolving of sediments in nitric acid, extraction conversion of concentrated solutions with the use of tributyl phosphate in hydrocarbon thinner and sedimentation of ammonium polyuranates from re-extracts thus obtained. Sedimentation of uranium at stage of concentration is performed with the use of sodium hydroxide at pH= 9-10 and temperature of 60-90C. Proposed method enhances purification of uranium from fluorine due to enhanced sedimentation and filtration properties of sediments at concentration stage. Content of admixtures in triuranium octa-oxide powders obtained from re-extracts by sedimentation of ammonium polyuranates and subsequent calcination does not exceed specified norms.
EFFECT: enhanced efficiency.
1 dwg, 2 tbl, 1 ex
The invention relates to technology for processing wrangelstrasse uranium waste.
A method of refining uranium waste (the Straits solutions from decontamination of equipment, damaged fallopian solutions, solid waste), including the dissolution of solid waste in solutions of nitric acid, mixing the obtained solution with liquid waste, filtration solutions, the concentration of the "poor" uranium solutions, extraction uranium extraction and purification from impurities with the use of tributyl phosphate in a hydrocarbon solvent as the extractant (A.A. Mayorov, Braverman IB Technology to obtain powders of ceramic uranium dioxide. - M.: Energoatomizdat, 1985, s-122).
In the above-mentioned method, the concentration of the "poor" uranium solutions produced by the process of evaporation.
In the processing of waste containing fluorine, the latter corrodes the equipment of steel 18CR10NITI because of its highly corrosive. In the process of evaporation does not occur purification solutions from fluorine, and the direction of extraction redistribution of solutions contaminated with fluorine, complicates the extraction stage. For binding of fluoride in solutions directed to the extraction redistribution, enter nitrate iron, forming with fluorine stable complex compounds. (Ritchie G.M., Ashbrook Extra AV is tion. Principles and applications in metallurgy. - M.: metallurgy, 1983, s.285).
A method of refining wrangelstrasse waste (RF Patent No. 2200992, IPC G21 9/04, 9/30, publ. 20.03.2003)adopted for the prototype, including the production of waste solutions, the stage of concentration of solutions by precipitation of uranium and the subsequent dissolution of the precipitate in nitric acid, the extraction of uranium from concentrated solutions using tributyl phosphate in a hydrocarbon diluent, reextraction and deposition of polyuranates ammonium received reextractors.
The concentration of the solutions in the method prototype, including deposition of uranium ammonium hydroxide in the form of polyuranates ammonium and their subsequent dissolution in nitric acid leads to the purification of uranium from fluorine. However, the clearance is insufficient, because during the precipitation of the ammonium hydroxide are formed fine sediments with low sedimentation and filtration properties, "exciting" fluoride from mother solutions.
The objective of the invention is to increase the degree of purification of uranium from fluorine by improving sedimentation and filtration properties of precipitation, obtained by precipitation from solutions on the operations of concentration.
The solution is achieved in that in the method of processing wrangelstrasse waste, including the production of these solutions, the stage to which tsentrirovannaja solutions by precipitation of uranium and the subsequent dissolution of the precipitate in nitric acid, extraction of uranium from concentrated solutions using tributyl phosphate in a hydrocarbon diluent, reextraction and deposition of polyuranates ammonium received reextractors, the deposition of uranium on the stage of concentration carried out with sodium hydroxide at pH 9-10 and the temperature of 60-90°C.
Nitric acid solutions of uranium, recyclable, were obtained by mixing solutions from dissolution Ogarkov with the operation of the fluoridation of octaoxide truran and pastes from cleaning equipment drain water solutions and irrigation fluids, the gas purification system. As a result of mixing of getting initial solution composition: 0.06 mol/l of uranium, 0.3 mol/l of nitric acid, 1.05 mol/l of fluoride ion, which is sent to the stage of concentration.
Carried out the deposition of uranium on the stage of concentration. In the deposition reactor with specified expenses filed the original uranium-fluorine-containing solution and a 40%solution of sodium hydroxide with constant stirring. In the reaction zone of deposition maintained pH 9-10 and the temperature of 60-90°
Sedimentation and filtration properties of the obtained precipitation was evaluated by filtration coefficient, the speed and timing of sedimentation and other characteristics, is shown in the drawing and in the table 1.
The drawing shows the dependence of the rate sedimen the purpose of precipitation, formed by deposition on the stage of concentration, V, mm/min, from the time of sedimentation t, min, for the proposed method (precipitation with sodium hydroxide) and the prototype method (precipitation with ammonium hydroxide).
Table 1 presents the characteristics of the sludge formed during the precipitation stage of concentration in the proposed method (lines 4-7) and the method-prototype (lines 1-3).
|Precipitator||The temperature of deposition, °||The ratio of the volume of the original solution to the volume of reagent precipitator||The relative amount of sediment, vol.%||The filtration coefficient, 10-6cm/sec||The cake moisture, wt.%||Specific surface area, m2/g||Density based, g/cm3||The density of the Sands, g/cm3||The content of components in the sediment, wt.%||The content of components in the mother solution, g/l|
|after 20 min||after 24 hours||uranium||fluoride||uranium||fluoride|
|NH4OH||60||0,5||51||26||3,1||62||37||3,48||0,7||of 60.5||0,73||0,015||of 5.4|
|NaOH||90||8,8||6,4||5,6||5,5||of 31.4||15,4||3,66||the 1.44||61,7||0,2||0,013||10,8|
From the data presented in table 1 and in the drawing, it is seen that the use of sodium hydroxide to precipitate uranium operations concentration can increase the permeability of the formed precipitation, rate of sedimentation, bulk and based density, to reduce the moisture content in the sediments, specific surface area and the volume of sediment occupied them after decanting. This increases the degree of purification of uranium from fluoride: fluoride content in the precipitation of uranium is reduced by 3-5 times compared with the prototype, and the uranium content in the mother solution remains on the same level as in the method prototype.
The use of sodium hydroxide on the operation of the concentration of uranium from wrangelstrasse solutions also can significantly reduce the amount of the produced mother solutions, which facilitates their disposal.
The obtained precipitates were dissolved in solutions of nitric acid of a given concentration and directed by extraction redistribution using tributyl phosphate in a hydrocarbon diluent and, further, ammonium deposition of polio is the Anat ammonium from reextractors uranium.
By improving the cleaning of precipitation of the fluorine at the stage of concentration on the extraction redistribution directed solutions with a significantly lower fluorine content than in the prototype that facilitates the extraction process (requires less nitrate of iron to bind fluoride).
The use of sodium hydroxide on the operation of concentrating the waste does not adversely affect the results of the extraction stage. On extraction the redistribution of concentrated solutions of uranium in the ratio of flows in the extraction surgery O:=1:3 were obtained technological indicators, which are presented in table 2 (row 1 - prototype method, line 2 - the proposed method).
|№ p/p||The content in the concentrated solution, g/l||The uranium content, g/l||The purification coefficient of uranium extraction operations|
|HNO3||U||F||Fe||water-tail solution||working extractant||F||Fe|
The content of impurities in powders octaoxide truran obtained from reextractors by deposition of polyuranates ammonium and subsequent calcination, do not exceed established standards.
A method of processing wrangelstrasse waste, including the production of these solutions, the stage of concentration of solutions by precipitation of uranium and the subsequent dissolution of the precipitate in nitric acid, the extraction of uranium from concentrated solutions using tributyl phosphate in a hydrocarbon diluent, reextraction and deposition of polyuranates ammonium received reextractors, characterized in that the deposition of uranium on the stage of concentration carried out with sodium hydroxide at pH 9-10 and the temperature of 60-90°C.
FIELD: environmental protection.
SUBSTANCE: invention concerns lands polluted with various organic and inorganic pollutants such as heavy metals, petroleum products an the like, and can be used for detoxification of various-type lands, e.g. in cases of man-caused pollution of lands, sewage disposal plant sediments etc. containing various types of pollutants in different concentrations. Method is implemented by adding glauconite-containing sorbent to land until specified concentration of polluting substance in the land is achieved. Prior to addition of sorbent, type of pollutant and its concentration K0 in polluted land sample is determined, after which concentrations K1, K2, K3, and K4 of polluting substance are measured for land-to-sorbent ratios 1:1, 1:2, 1:3, and 1:4, respectively, after which mass ms of the sorbent required to be mixed with land polluted with preliminarily determined pollutant in concentration K0 is determined to achieve desired concentration of pollutant K3 in terms of following equation: ms = mL*K1/[K3*(K0/K1 + K1/K2 + K2/K3 + K3/K4)4], where mL is mass of land polluted with preliminarily determined pollutant in concentration K0, and thereafter polluted land is moistened and calculated mass of sorbent is spread across the surface of polluted land while simultaneously being mixed with polluted land.
EFFECT: increased accuracy in determining mass of sorbent required and sufficient to achieve required norms of concentration of polluting substance in ground and so to reduce consumption of the sorbent.
5 cl, 3 ex
FIELD: inorganic synthesis.
SUBSTANCE: invention, in particular, relates to preparing nitrate salts of uranium and actinides and provides alternative way for transforming starting materials, containing oxides of uranium and other nuclear materials into hydrated nitrates, i.e. products convenient for further processing. Preparation of hydrated actinide nitrates is accomplished via direct reaction of actinide oxides with nitrogen tetraoxide/water mixture in sealed container at overpressure 0.5-1.0 MPa and temperature 100-140°C or with liquid tetraoxide/water/carbon dioxide mixture at pressure 7.0 MPa and 10-75°C.
EFFECT: enabled simple and convenient oxide conversion method with degree of conversion.
2 cl, 3 tbl, 5 ex
FIELD: supercritical and subcritical extraction of metals; actinide extraction.
SUBSTANCE: proposed extraction mixture incorporates β-diketone and additional chelate in solvent. Used as solvent is mixture incorporating liquid solvent or supercritical fluid and as additional chelate, oxygen-containing organic compounds undecomposable in the course of distillation at normal pressure, such as ethers, esters, lower acid amides, and ketones. Chelates used for the purpose can be easily reconditioned and reused.
EFFECT: reduced amount of waste water in recovering of irradiated fuel.
FIELD: nuclear engineering; preservation of dry, wet, and liquid radioactive wastes.
SUBSTANCE: proposed composition has resin portion of cold-cured compound ATOMIK and filler. Resin portion ingredients are as follows, parts by weight: epoxy oligomer, 100;, curing agent (aromatic amines), 38-50 furfural, 9-11. Used as filler is composition incorporating following ingredients, parts by weight: cement, 50-100; marshalite, 50-100 or bentonite, 50-100, or when they are jointly used: marshalite, 90-100 and bentonite, 90-100. Such composition provides for desired radiation resistance in absence of leaching of alpha-, beta-, and gamma-active radionuclides from preserved specimens of reactor graphite.
EFFECT: enhanced radiation stability of preserved specimens free from pits and voids, and adequate lifetime of preserved wastes; ability of their depreservation.
1 cl, 2 dwg, 2 tbl, 2 ex
FIELD: recovery of spent fuel.
SUBSTANCE: proposed method for recovering plutonium-containing sorbents of alkali metal fluorides is characterized in that sorbents are treated with water vapor or vapor-air mixture at temperature of 300 to 1000 °C. Hydrogen fluoride produced in the process is removed. After that plutonium dioxide is extracted from reaction products.
EFFECT: facilitated procedure, reduced cost.
3 cl, 1 ex
FIELD: atomic engineering.
SUBSTANCE: proposed device has pipe with flanges at ends for connection to container flange and to flange of sleeve installed on filter flange, flexible hose one of whose ends is connected to pipe end, and manifold for accumulating radioactive sorbent extracted from filter; this manifold is made in the form of concave star whose arms are made in the form of rotary tubes. Hollow cylinder mounted in star center on concave part end accommodates spring-loaded rod with counterpoise; other end of flexible hose is connected to concave star by means of flexible coupling.
EFFECT: enhanced operating reliability and simplified design of device.
4 cl, 2 dwg
FIELD: systems for processing irradiated nuclear fuel of power generation reactors, possibly in application radiochemistry for separating ruthenium out of insoluble residues after processing irradiated nuclear fuel, recovery of ruthenium out of waste catalysts or other technical products.
SUBSTANCE: method comprises steps of placing insoluble residues in electrolyzer filled with nitric acid solution with added silver nitrate; supplying electric current for transmitting easily volatile formed RuO4 by action of air passing through electrolyzer to apparatus filled with absorbing agent.
EFFECT: possibility for separating ruthenium out of insoluble radioactive residues without burying secondary radioactive deposits due to complete dissolving of initial material.
FIELD: nuclear engineering.
SUBSTANCE: proposed method that can be used for decontaminating radionuclide-contaminated metal surfaces of various nuclear power installations, manufacturing and other pieces of equipment, including those having complex configuration and subject to disposal and burial, involves their scanning by contact-arc discharges from current supply having flat current-voltage characteristic of at least 280 A/V at voltage of 7 - 4 V across working electrodes; granules of contaminated metal brought out of decontamination zone are sized to minimum 0.05 mm.
EFFECT: enhanced productivity and personnel safety.
FIELD: nuclear engineering.
SUBSTANCE: proposed method for removing spent nuclear fuel cladding includes following steps: cutting of spent fuel elements into fragments and separation of these fragments into part of fuel rods and part of spent nuclear fuel. Fuel elements are made of austenitic stainless steel. Cutting step lasts until main part of fragments measuring below 2 mm is obtained; separation step involves magnetic separation. Device implementing proposed method has cutting unit that functions to cut spent fuel rods into fragments. Mentioned cutting unit has rotary cutting tool incorporating parallel knives and shield that holds fragments until they are finely cut. Provision is made for magnetic separator that functions to magnetically separate fragments produced by cutting unit.
EFFECT: enhanced fragment separation efficiency.
5 cl, 5 dwg
FIELD: decontaminating solid iodine filters used in nuclear industry.
SUBSTANCE: proposed method includes bringing filters in contact with aqueous solution of reducing agent chosen from hydroxylamine, hydroxylamine salts, ascorbic acid, ascorbic acid salts, mixed ascorbic acid anhydrides, sodium boron hydride, sodium hypophosphate, formaldehyde, urea, formic acid, and their mixtures so as to extract iodine from filter and to dissolve it in aqueous solution. Silver can be also dissolved at the same time or sequentially in reducing agent or in any other suitable aqueous solution.
EFFECT: enhanced degree of decontamination, facilitated procedure using aqueous solution and simple vat.
FIELD: processing uranium-containing products formed at extraction of uranium from solutions followed by re-extraction by means of ammonium carbonates; extraction of uranium and accompanying valid components from ores.
SUBSTANCE: proposed method includes thermal dissociation at sedimentation of uranium, entrapping of ammonia and carbon dioxide from waste gases. Thermal dissociation of uranium-containing ammonium carbonate solutions is performed at temperature of 70-85°C to pH= 6.5-5.9 at simultaneous blowing of gases by air; solutions obtained after thermal dissociation are separated from uranium-containing sediment and accompanying valid components, molybdenum for example are extracted from them.
EFFECT: enhanced efficiency of utilization of ammonia and carbon dioxide; high degree of separation of uranium and admixtures; extraction of accompanying valid components, molybdenum for example.
2 cl, 1 tbl, 2 ex
FIELD: hydraulic metallurgy.
SUBSTANCE: method comprises extracting saturated ionite from the pulp, washing it with water, desorbing uranium, washing desorbed ionite to decrease acidity, separating by wet screening into 1.0±0.2-mm size, extracting silicon from the under-screen product, and discharging it and above-screen product to the uranium sorption.
EFFECT: reduced ionite consumption.
1 cl, 1tbl
SUBSTANCE: extractant has bi-phosphorus acid and additionally has tri-phosphate with relation of said components (0,5-1,25):1. Method for producing extractant includes adding to 2-ethylhexanole of chlorine oxide of phosphorus with their relation (4,5-5,1):2,0, and with parameters determined by reaching fullness of passing of reaction, after that reaction mixture is exposed until full removal of formed chlorine hydrogen, then to received mixture 1 mole of water is added, mixture is exposed to full hydrolysis. Then mixture is washed ad water layer is separated from organic remainder, containing said bi-phosphoric acid and tri-phosphate.
EFFECT: higher efficiency.
2 cl, 1 dwg, 2 tbl, 4 ex
FIELD: uranium technologies.
SUBSTANCE: method comprises sorption of uranium on low-basicity anionites, desorption of uranium, and recovery of finished product. In particular, uranium-saturated low-basicity anionite is converted into OH- form and uranium into soluble stable complex [UO2(CO3)3]-4 by treating sorbents with alkali metal and ammonium carbonate solutions.
EFFECT: achieved complete desorption of uranium and simultaneously sorbent is freed from poisons and other sorption components.
FIELD: chemical technology; deactivation and decontamination of radioactive industrial products and/or wastes.
SUBSTANCE: proposed method designed for deactivation and decontamination of radioactive industrial products and/or production wastes incorporating Th-232 and its daughter decay products (Ra-228, Ra-224), as well as rare-earth elements, Fe, Cr, Mn, Al, Ti, Zr, Nb, Ta, Ca, Mg, Na, K, and the like and that ensures high degree of coprecipitation of natural radionuclides of filtrates, confining of radioactive metals, and their conversion to environmentally safe form (non-dusting water-insoluble solid state) includes dissolution of wastes, their treatment with barium chloride, sulfuric acid, and lime milk, and separation of sediment from solution. Lime milk treatment is conducted to pH = 9-10 in the amount of 120-150% of that stoichiometrically required for precipitation of total content of metal oxyhydrate; then pulp is filtered and barium chloride is injected in filtrate in the amount of 0.4 - 1.8 kg of BaCl2 per 1 kg of CaCl2 contained in source solution or in pulp and pre-dissolved in sulfuric acid of chlorine compressors spent 5-20 times in the amount of 0.5 - 2.5 kg of H2SO4 per 1 kg of BaCl2. Then lime milk is added up to pH = 11 - 12 and acid chloride wash effluents of equipment and production floors are alternately introduced in sulfate pulp formed in the process at pulp-to-effluents ratio of 1 : (2-3) to pH = 6.5 - 8.5. Filtrate pulp produced in this way is filtered, decontaminated solution is discharged to sewerage system, sediment of barium and calcium sulfates and iron oxysulfate are mixed up with oxyhydrate sediment formed in source pulp neutralization, inert filler and 0.5 - 2 parts by weight of calcium sulfate are introduced in pasty mixture while continuously stirring them. Compound obtained in the process is placed in molds, held therein at temperature of 20 - 50 oC for 12 - 36 h, and compacted in blocks whose surfaces are treated with water-repelling material.
EFFECT: reduced radioactivity of filtrates upon separation of radioactive cakes.
8 cl, 1 dwg, 1 ex
FIELD: chemical technology; recovery of deactivated and decontaminated radioactive industrial wastes.
SUBSTANCE: proposed method that can be used for deactivating and decontaminating industrial radioactive wastes incorporating Tb-232 and their daughter decay products (Ra-228, Ra-224), as well as rare-earth elements, Fe, Cr, Mn, Sl, Ti, Zr, Nb, Ta, Ca, Mg, Na, K, and the like includes dissolution of wastes, treatment of solutions or pulps with barium chloride, sulfuric acid, and lime milk, and separation of sediment from solution. Lime milk treatment is conducted to pH = 9 - 10 in the amount of 120-150% of total content of metal oxyhydrates stoichiometrically required for precipitation, pulp is filtered, and barium chloride in the amount of 0.4 - 1.8 kg of BaCl2 per 1 kg of CaCl2 contained in source solution or in pulp, as well as pre-diluted sulfuric acid spent 5 - 20 times in chlorine compressors in the amount of 0.5 - 2.5 kg of H2SO4 per 1 kg of BaCl2 are introduced in filtrate. Alternately introduced in sulfate pulp formed in the process are lime milk to pH = 11 - 12, then acid chloride wash effluents from equipment and industrial flats at pulp-to-effluents ratio of 1 : (2 - 3) to pH = 6.5 - 8.5, and pulp obtained is filtered. Decontaminated solution is discharged to sewerage system and sediment of barium and calcium sulfates and iron oxysulfate are mixed up with oxyhydrate sediment formed in source pulp neutralization process; then 35 - 45 mass percent of inert filler, 10 - 20 mass percent of magnesium oxide, and 15 -m 25 mass percent of magnesium chloride are introduced in pasty mixture formed in the process while continuously stirring ingredients. Compound obtained is subjected to heat treatment at temperature of 80 - 120 oC and compressed by applying pressure of 60 to 80 at.
EFFECT: reduced radioactivity of filtrates upon separation of radioactive cakes due to enhanced coprecipitation of natural radionuclides.
7 c, 1 ex
FIELD: rare, dispersed and radioactive metal metallurgy, in particular hydrometallurgy.
SUBSTANCE: invention relates to method for reprocessing of polymetal, multicomponent, thorium-containing radwastes, formed when reprocessing of various mineral, containing rare-earth elements, Nb, Ta, To, V, Zr, Hf, W, U, etc. Method includes treatment of solution and/or slurry with alkaline agent; introducing of sulfate-containing inorganic compound solution and barium chloride; treatment of obtained hydrate-sulfate slurry with iron chloride-containing solution, and separation of radioactive precipitate from solution by filtration. As alkali agent magnesia milk containing 50-200 g/dm2 of MgO is used; treatment is carried out up to pH 8-10; sodium sulfate in amount of 6-9 g Na2SO4/dm2 is introduced as solution of sulfate-containing inorganic compound; barium chloride solution is introduced in slurry in amount of 1.5-3 g BaCl2/dm2. Hydrate-sulfate slurry is treated with solution and/or slurry containing 0.8-16 Fe3+/dm2 (as referred to startingsolution) of iron chloride, followed by treatment with high molecular flocculating agent and holding without agitation for 0.5-2 h. Radioactive precipitate is separated from mother liquor, washed with water in volume ratio of 0.5-2:1; then washed with sodium chloride-containing solution and/or slurry in volume ratio of 0.5-2:1; radioactive precipitate is removed from filter and mixed with mineral oxides in amount of 0.5-0.8 kg MgO to 1 kg of precipitate. Formed pasty composition is fed in forms and/or lingots and presses with simultaneous heating up to 80-1200C.
EFFECT: filtrate with reduced radioactivity due to increased codeposition coefficient of natural Th-232-group radioactive nuclide, in particular Ra-224 and Ra-228, with radioactive precipitates.
10 cl, 1 ex
FIELD: ferrous and precious metallurgy, in particular, processes for extraction of precious metals from affinage production wastes.
SUBSTANCE: method involves leaching out material containing precious metals and lead with the use of sulfuric acid solution having concentration of 150-300 g/l; subjecting sulfuric acid leaching cake to leaching out in sodium chloride solution without addition of sulfuric acid. Method allows lead to be more completely extracted from processing circuit.
EFFECT: provision for producing of stable lead-containing solutions, and improved quality of platinum metal concentrates.
1 tbl, 7 ex