The method of processing of uranium-containing compositions

 

(57) Abstract:

Usage: in the processing of uranium-containing materials, namely, in the processing of uranium-aluminum compositions to ensure an effective and environmentally safe extraction of the commodity composition of nitrous oxide, uranium and refined aluminum metal. The inventive uranium-aluminum composition is brought into contact with the carbon component, perform manual heating in vacuum insulated exposures at the melting temperature of the intermetallic compounds, hold the vacuum distillation of aluminum, translate uranium component in the refractory carbide connection, carry out the decomposition of the carbide of aluminum during isothermal holding at the temperature of dissociation, uranium carbide compound is cooled, crushed, spend oxidizing roasting to remove carbon and formation of nitrous oxide of uranium and conduct its hydrometallurgical treatment.

The invention relates to methods of processing of uranium-containing materials, namely the processing of uranium-aluminum compositions.

These compositions at a concentration of aluminum from 72 to 86 wt.% consist of aluminum metal and the aspects of the number (up to several percent), other compounds of aluminum, for example, AlSi3, Al2Zr, Al2O3due to impurities introduced in the composition of the starting reagents (uranium and aluminum) and technological components at the production stage compact products (N2O2, Si, Fe, Zr and others).

The task of processing the uranium-aluminum compositions to extract from them the nitrous-oxide of uranium is an urgent problem of development of an environmentally safe and relatively inexpensive process of removing components. Its solution will significantly reduce the amount of disposed radioactive and chemically hazardous uranium-aluminum waste.

Reactivity of aluminum is not possible with the known methods of processing of uranium-containing compositions to ensure its recovery in the form of pure metal without additional recovery operations and cleanup.

Known methods of hydrometallurgical processing of uranium-aluminum alloys based on the dissolution of the compositions in nitric acid and alkali with the use as catalyst of mercury; the process of extraction or Stripping using organic extractants; subsequent refining of uranium from primes the quality of the finished product. (See "Processing of nuclear fuel", edited by S. Carpenter and P. Richard, Moscow, Atomizdat, 1964, pages 63-67, 76-86; "Processing of fuel from power reactors" Collection of articles, Moscow, Atomizdat, 1972)

A disadvantage of known methods is that aluminum is not separated from the uranium before extraction, which requires the preparation of large volumes of solutions (7000 l, per 1 kg of uranium) to ensure the required purity nitrous oxide uranium in aluminum and other impurities. In addition, waste from processing contains a lot of mercury, which causes corrosion and complicates the process of recycling and leads to a significant loss of uranium and the discharge of toxic substances into the environment, which determines the environmental risk of production. There is a potential risk of explosion due to the presence of hydrogen and oxygen in the exhaust gases during processing. Used chemical methods do not allow to directly obtain aluminum metal.

Closest to the claimed method for solving the technical problem of the prototype - is a method of processing uranium-beryllium compositions comprising heating to melt; vacuum distillation and condensation of beryllium; crystallization of non-volatile is to be placed; filtering of uranyl nitrate and its dual peroxide precipitation at a pH of 1.5-2.0, with peroxide after each deposition calcined in air at a temperature of 750-800oC for 2 h, and the condensate beryllium distil under vacuum at a pressure not exceeding 110-5Thor and the temperature of 1400-1500oC (see the patent of Russia N2106029, MK G 21 C 19/44, C 01 G 43/01, C 22 B 35/00, from 27.02.1998,).

The disadvantage of this method is that at the stage pyrometallurgical process is not deleted technological impurities and remains up to 5 wt.% beryllium, which are in the process of burning uranium component in the oxide, which causes the holding peroxide deposition to finish cleaning nitrous-oxide of uranium. Additionally, the uranium content of 0.01 wt.% requires vacuum distillation to reduce the uranium content in the resulting beryllium to an acceptable level.

The aim is to develop a technological process of processing of the uranium-aluminum compositions for achieving the goal of the invention is an effective and environmentally safe extraction of the compositions trademarks of nitrous oxide, uranium and refined aluminum metal.

This goal is achieved in the ex is carried out stepwise heating in vacuum insulated exposures at the melting temperature of the intermetallic compounds; hold the vacuum distillation of aluminum; translated uranium component in the refractory carbide compounds; conduct the decomposition of the carbide of aluminum during isothermal holding at the temperature of dissociation; uranium carbide connection cool; grind; conduct oxidizing roasting to remove carbon and formation of nitrous oxide of uranium; and not evaporated technological impurity delete the hydrometallurgical processing of the received product.

The essence of the proposed method is as follows.

Contact uranium-aluminum alloys with a carbon component (carbon black, graphite, carbon fiber) necessary to ensure that at the stage of melting intermetallic associate uranium carbide compound with a melting point at 1700-1800oC higher than the melting point of aluminum.

On stage pyrometallurgical processing (distillation of aluminum in vacuum ensures the efficient separation of uranium-aluminum alloy components with different vapor pressure for 10-12 orders of magnitude, which allows you to selectively allocate metallic aluminum, in the form of intermetallic compounds and metal.

The process of education uransoderzhashchie 1000-1200oC on one mole of the original uranium-aluminum composition. Such temperature increases can lead to the destruction of the snap and evaporation of uranium, which is not connected in the carbide compound. To eliminate this effect, the process is carried out by stepwise isothermal exposures at the melting temperature of the intermetallic compounds of uranium, during which the melt carbodiimide without avalanche development process.

The first isothermal aging is carried out at a melting temperature UAl4(750oC), the second melting UAl3(1350-1400oC) and the third at the melting temperature of UAl2(1600oC). It was established experimentally that exposure for 5-10 min at the temperature of melting intermetallics enough to complete the process of carbidization and that the temperature did not rise more than 50-100oC from the melting point of the corresponding intermetallic. Released from the formation of carbides heat to be effectively spent on evaporation of aluminum. In the process of raising temperature and isothermal exposures of the aluminum manages to form carbides of variable composition (Al3C4, AlC2), the decomposition temperature of which lies in the interval 2150-2200oC. Therefore, dalmasi the s from carbides of aluminum.

It was established experimentally that the aluminium content in the uranium carbides does not exceed 310-4wt.% The concentration of uranium in aluminum condensate not more than 210-3wt.%.

Uranium carbide (UC2, UC) are usually in the form of sintered conglomerates and contain (up to several percent free carbon. To remove carbon and transfer of uranium oxide compounds conduct oxidative roasting pre-crushed to a particle size of 100-200 µm carbides. The firing in air at a temperature of active oxidation of carbon in the carbide compounds (600-800oC) to remove the carbon. The process is finished after the termination of allocation of CO determined chromatography method.

Hydrometallurgical purification obtained nitrous-oxide of uranium is carried out to remove impurities remaining in the material, from the additives in the original uranium-aluminum composition of the elements and their carbides having a low vapor pressure, which cannot be removed in the temperature interval held by the pyrometallurgical process.

An example of the method.

1. Pyrometallurgical processing of uranium-aluminum composition.

silicon was placed on the graphite cloth and placed in a graphite crucible, which was installed in the vacuum furnace equipped with a sealed device and the condenser for preventing the flow of evaporated components in the internal volume of the furnace.

Heating load started when reaching into the furnace volume of the vacuum not lower than 110-4Thor and supported him throughout the entire process. The speed of temperature rise during the entire process was supported by the maximum possible for the design of the furnace, which was regulated only by the inertia of the load and amounted to 2000 deg./hour.

The first exothermic effect, spontaneous temperature rise of 100 - 150oC, occurred in the temperature range of 700-800oC and disappeared at a speed furnace at a constant rate after 5 minutes the Second exothermic effect was observed in the range of 1300-1400oC. the Temperature spontaneously rose to 200-250oC and recovered after 7 min of exposure. The third exothermic peak appeared in the range of 1500-1600oC with spontaneous rise in temperature 250-300oC. At a speed of 10 min was set the desired temperature of the process. Subsequent rise in temperature to 2150-2200oC exothermic effects were not observed, as the uranium component preparatory to the point of decomposition of the carbide of aluminum were observed decrease in vacuum to 110-2Tor. Upon reaching the temperature of decomposition of the carbide aluminum vacuum recovered to 110-4Thor after exposure to 1.5-2.0 hours.

The resulting thermal annealing the sintered uranium-bearing conglomerate and aluminum condensate were analyzed by spectral and x-ray diffraction analyses. Conglomerate consisted of carbides UC2, UC (Zr0,7Ufor 0.3C and free carbon. The aluminium content was 1,510-4wt. %, silicon - 310-4wt.% The sediment in the condenser consisted of refined aluminum metal content in the surface layer ( 40-50 microns) - 210-3wt.% uranium and XRD measurements showed values within the natural background.

2. Processing of uranium carbide conglomerate.

The sintered conglomerate uranium carbides was crushed by a hydraulic press in the environment of trichloroethylene to a particle size of 100-200 μm. The powder was loaded in a rotating quartz tube and heated in air to a temperature of active oxidation of carbon in the carbide compounds (700oC). The formed gas (CO) were taken from the zone of interaction through the filter system. The process was interrupted after CLASS="ptx2">

The resulting oxidative annealing the material consisted of nitrous oxide uranium (U3O8) - the 90.8 wt.% and 9.2 wt.% the uranium-zirconium spinel composition (Ufor 0.3Zr0,7)O2. The zirconium content was 3.5 wt%. Cleaning nitrous oxide uranium known for use in the hydrometallurgical production method using nitrogen, sulfuric acid and an aqueous solution of ammonia at their total consumption of 8.7 litres per one kilogram of uranium allowed to obtain enriched uranium dioxide with a total content of impurities 0,083 wt.%, including 0.005 wt.% zirconium.

The practical implementation of the proposed method shows that the proposed solution allows you to efficiently convert the uranium-aluminum composition trademark mixed oxide of uranium and refined metal aluminum, which cannot be obtained by known methods. The inventive method is carried out on standard equipment with security measures for servicing personnel and the environment, is easily controlled, does not require distillation of the condensate of aluminum, and the use of chemical reagents by 2-3 orders of magnitude less than in the hydrometallurgical method.

the blowing hydrometallurgical processing, characterized in that in the processing of uranium-aluminum compositions they are brought into contact with the carbon component, perform manual heating in vacuum insulated exposures at the melting temperature of uranium intermetallics, hold the vacuum distillation of aluminum, translate uranium component in the refractory carbide connection, carry out the decomposition of the carbide of aluminum during isothermal holding at the temperature of dissociation, uranium carbide compound is cooled, crushed, spend oxidizing roasting to remove carbon and formation of nitrous oxide of uranium and spend hydrometallurgical processing.

 

Same patents:

The invention relates to technologies of production of the medical isotope Mo-99 from irradiated fuel based on uranium

The invention relates to technologies of production of the medical isotope Mo-99 from irradiated fuel based on uranium

The invention relates to radiochemical technology and can be used for dissolving nuclear fuel pieces of cylindrical casings of the spent fuel rods of a nuclear reactor

The invention relates to the processing of highly enriched uranium (HEU), especially weapons into low enriched uranium (LEU) energy purposes by diluting HEU
The invention relates to the manufacture and use of a mixture of isotopes of uranium, nuclear fuel for nuclear reactors of nuclear power plants

The invention relates to the field of producing compounds for nuclear reactor fuel, in particular to the purification of uranium from plutonium
The invention relates to methods of processing of uranium-containing compositions, in particular to the processing of uranium-beryllium compositions containing 1-90 wt

The invention relates to a device for dissolving nuclear fuel pre-shredded fuel assemblies (FA) of nuclear reactors and can be used at the radiochemical plant regeneration nuclear fuel spent fuel assemblies of different nuclear reactors
The invention relates to the field of extraction reprocessing of irradiated nuclear fuel

The invention relates to the field of metallurgy of non-ferrous metals and can be used to obtain aluminum alloys from recycled materials, such as silumins toxins from aluminum production

The invention relates to the field of non-ferrous metallurgy and can be used to extract metal and other valuable components from the waste production of alloys based on aluminium, in particular silumins

The invention relates to the processing of uranium metal and can be used in the processing of uranium scrap, recycled uranium, and especially when converting weapons-grade uranium into fuel for power reactors

The invention relates to the handling of depleted uranium mixtures, in particular to a method for recovering anhydrous hydrogen fluoride from depleted uranium hexafluoride
The invention relates to methods of processing of uranium-containing compositions, in particular to the processing of uranium-beryllium compositions containing 1-90 wt

The invention relates to a technology for dioxide uranium and oxide compositions used in nuclear technology
Up!