The method of processing metal scrap molybdenum contaminated with uranium oxides

 

(57) Abstract:

The invention relates to the field of recycling. The inventive processing methods, including oxidation of waste metal molybdenum pure oxygen or oxygen in a horizontal reactor at a temperature of 650-S. Then carry out the condensation of molybdenum trioxide in the external capacitors at a temperature of 15 to 40S. Subsequent clearing of octoxyglycerin produced by vacuum sublimation at a temperature of 450-S and a residual pressure of 103-104PA. Advantages of the invention are to reduce the number of stages and reducing energy consumption.

The invention relates to technology for processing waste containing valuable items or represent an environmental hazard, and can be used for processing wastes of refractory metals of the sixth group.

A method of refining metal scrap molybdenum [Zelikman A. N., The molybdenum. - Metallurgy, 1970. - S.], based on the oxidation of the latter in a stream of air or oxygen to molybdenum trioxide. Oxidation of metal waste molybdenum is carried out in furnaces: muffle, drum-rotating, multiple-hearth and the majority of the impurities, related molybdenum, do not dissolve. From the ammonia solution of purified molybdenum can be isolated by crystallization paramolybdate ammonium deposition tetramolybdate, deposition of molybdenum acid or deposition of powellite Samoa4.

The disadvantages of this method is a multi-stage process and the inability to use this method for processing and extraction of uranium.

There is a method of recycling uranium impurities [C. B. Shevchenko, B. N. Sudarikov. The technology of uranium. - M.: Gosatomizdat, 1961. - 330c.], based on the oxidation of waste and subsequent dissolving them in concentrated nitric acid or in a mixture of hydrochloric and sulphuric acids. Insoluble in nitric acid impurities are filtered and then removed to the dump. Next, the nitric acid solution of uranium goes on stage extraction purification from impurities Mo, W, Re, Fe, si, Th, Cl, Br, J, F, etc. Extraction cleaning is performed by tributyl phosphate, dibutylbarbituric, hexanol and other extractants in Packed columns of stainless steel. Reextracted is demineralized water columns without attachments and pulsations. The organic phase after Stripping regenerated and returned to extracte received trioxide uranium satisfies the requirements of nuclear purity.

The disadvantages of this method is a multistage process, large amounts of spent reagents, the use of expensive extractants. In addition, in this method it is possible to recycle waste where macromolecules is uranium, and molybdenum - microcrystal.

A known method of producing dioxalate molybdenum high purity, based on the chlorine dioxide molybdenum to dioxalate with subsequent sublimation of the compounds obtained. [Application Method of producing dioxalate molybdenum high purity, No. 1487463, IPC 22, 34/34]. The method consists in the preliminary heat treatment of the oxide of molybdenum and 1 to 3% of molybdenum trioxide in a confined space with a 650-C for 5-6 h at an initial pressure of 10-2mm RT. Art. After cooling dioxide molybdenum glorious for 8 hours at a temperature of 180 to 300C. The resulting dioxalane molybdenum sublime at 180C.

The disadvantages of the method is a multi-stage process, the long duration of the process and the inability to use this method for recycling of metallic molybdenum contaminated with uranium oxides.

The closest in technical essence and the achieved result is when the R elements. O'clock 3. Ed. by K. A. Bolshakova. - M.: Higher school, 1976. - S.]. The method consists in the oxidation of the latter in a stream of air or oxygen to molybdenum trioxide followed by chlorination. The chlorination process is carried out in the chlorinators at elevated temperatures. As glorieuses agent use chlorine, carbon tetrachloride, thionyl chloride, phosgene, etc. resulting from the chlorination of chloride impurities and chlorides of molybdenum distills from the reactor and separately condensed. In the further rectification chlorination products can be obtained molybdenum compounds of high purity, of which the methods of dissociation or metallothermy receive appropriate metals.

The disadvantages of this method is a multistage process, a large consumption of electric power for activation of the chlorination process and the inability purification of molybdenum from uranium.

The objective of the invention is to reduce the number of stages and operations when working with radioactive waste, reducing energy consumption through the use of the heat of reaction released during oxidation of metallic molybdenum and molybdenum, stripped of uranium.

The specified task Grana, oxidized in a stream of oxygen or oxygen at the initial temperature of 650-S; the reaction products - vozokany trioxide molybdenum condense in the external capacitors at a temperature of 15 to 40S, the molybdenum trioxide is additionally clear of octoxyglycerin vacuum sublimation at a temperature of 450-S at a residual pressure of (1-10)103PA. Reducing the number of stages is due to the fact that the waste is oxidized in a stream of oxygen or oxygen; the resulting products - trioxide of molybdenum and octaoxide truran have a big difference in the value of the elasticity of steam: at a temperature of 800C vapor pressure so the separation of uranium trioxide from octaoxide truran during vacuum sublimation purification occurs in one stage. The molybdenum trioxide is sublimated and shock gas is removed from the reactor, and octaoxide truran with non-volatile impurities remains in the reactor.

The energy consumption of the proposed method is reduced due to the fact that the process of oxidation of molybdenum in oxygen under certain conditions could be leaking into the combustion mode and heating the reactor up to 700-S only required for initiating the reaction.

Example 1.

The powder metallicheskih is,3 g placed in a quartz boat, which is installed in a horizontal reactor, heated by an electric heater. Heat the reactor to a temperature of 650C, include the supply of oxygen consumption, which amounted to 0.2 l/min, and carry out the oxidation process. After 5 minutes, the oxidation of metallic molybdenum has reached 16%, the time for complete oxidation of molybdenum under these conditions was 150 minutes the Formed molybdenum trioxide was partially wonganella directly in the oxidation process. The degree of sublimation of the molybdenum trioxide in the oxidation process did not exceed 6.6 mg/hour (2,2%). Direct voshon of molybdenum trioxide (“direct voshon” - trioxide of molybdenum, deposited from the gas phase onto the cold end of the quartz reactor) did not contain uranium. The remaining molybdenum trioxide from the oxidation reactor is placed in the apparatus for vacuum sublimation and conduct the process at a temperature of 450C and a residual pressure of 104PA. Desublimate - trioxide of molybdenum did not contain uranium. The obtained powder of molybdenum trioxide restore the hydrogen to metal in two stages in sequence 900, and then when S.

Example 2.

The molybdenum metal powder contaminated with uranium oxides (0.5% mass. U), with a specific surface area S=0,083 mwhich by the electric heater. Heat the reactor to a temperature of 700C, include the supply of oxygen consumption, which amounted to 0.2 l/min, and carry out the oxidation process. After 5 minutes, the oxidation of metallic molybdenum was 59%, the time for complete oxidation of molybdenum under these conditions was 20 minutes the Formed molybdenum trioxide was partially wonganella directly in the oxidation process. The degree of sublimation of the molybdenum trioxide in the oxidation process did not exceed 10,8 mg/hour (3.6 per cent). Direct voshon of molybdenum trioxide did not contain uranium. The remaining molybdenum trioxide from the oxidation reactor is placed in the apparatus for vacuum sublimation and conduct the cleanup process at a temperature of 650°C. and a residual pressure of 104PA. Desublimate - trioxide of molybdenum did not contain uranium. The resulting powder was reactivated by hydrogen to the metal in two stages in sequence 900, and then when S.

Example 3.

The molybdenum metal powder contaminated with uranium oxides (0.5% mass. U), with a specific surface area S=0,083 m2/g in the amount of 0.3 g was placed in a quartz boat, which is installed in a horizontal reactor, heated by an electric heater. Heat the reactor to a temperature S include oxygen, the second molybdenum reached 74%, the time for complete oxidation of molybdenum under these conditions was 10 minutes the Formed molybdenum trioxide was partially wonganella directly in the oxidation process. The oxidation of metallic molybdenum occurs with inflammation. The degree of sublimation of the molybdenum trioxide in the oxidation process was 126 mg/hour (42%). Direct voshon of molybdenum trioxide did not contain uranium. The remaining molybdenum trioxide from the oxidation reactor is placed in the apparatus for vacuum sublimation and conduct the process at a temperature T and a residual pressure of 104PA. Desublimate - trioxide of molybdenum did not contain uranium. The resulting powder was reactivated by hydrogen to the metal in two stages in sequence 900, and then when S.

Example 4.

The molybdenum metal powder contaminated with uranium oxides (0.5% mass. U), with a specific surface area S=0,083 m2/g in the amount of 0.3 g was placed in a quartz boat, which is installed in a horizontal reactor, heated by an electric heater. Heat the reactor to a temperature S include the supply of oxygen, the consumption of which was 0.2 l/min, and carry out the oxidation process. After 5 minutes, the oxidation of metallic molybdenum reached 71%, time pologalsja directly in the oxidation process. The oxidation of metallic molybdenum occurs with inflammation. The degree of sublimation of the molybdenum trioxide in the oxidation process did not exceed 292 mg/h (98%). Direct Vashon trioxide of molybdenum contained uranium in the amount of 0.001% of the mass. on U. the Remaining molybdenum trioxide from the oxidation reactor is placed in the apparatus for vacuum sublimation and conduct the process at a temperature T and a residual pressure of 104PA. Desublimate - trioxide of molybdenum did not contain uranium. The resulting powder was reactivated by hydrogen to the metal in two stages in sequence 900, and then when S.

The rationale for the temperature interval oxidation: at temperatures below 650C speed of the process is low, and at temperatures above S oxidation in combustion mode, while convective flows is captured particles octaoxide truran, and direct Vashon contaminated by uranium. In the proposed method is twofold purification from uranium compounds. Stage vacuum sublimation purification is carried out in the range of temperatures 450-C and a pressure of 103-104PA (10-1-10-2ATM). At higher temperatures and discharge was also observed convective transport of volatile ingredients of octaoxide taurana in desublimate and, Sona, including oxidation, condensation and purification, characterized in that the waste metal molybdenum oxidizes pure oxygen or oxygen in a horizontal reactor at a temperature of 650-S, molybdenum trioxide condense in the external capacitors at a temperature of 15-40S and clear of octoxyglycerin vacuum sublimation at a temperature of 450-S and a residual pressure of 103-104PA.

 

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