Method for recovering less-common and rare-earth metal production wastes

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

 

The present invention relates to chemical technology, particularly to a technology of inorganic substances and can be used for the processing, disposal and decontamination of radioactive waste containing Th-232 and child products of disintegration (Ra-228, Ra-224), and REE, Fe, Cr, Mn, Al, Ti, Zr, Nb, TA, CA, Mg, Na, K, etc. of the Invention can be used for processing multicomponent complex intermediates, industrial products containing natural radionuclides, industrial products and/or waste generated at different stages of technological processes of complex processing of loparite, zircon, ilmenite concentrates, sludge dump ferrocolumbium production, tailings wet magnetic separation of titanomagnetites, red slime aluminum production waste from the processing of columbite, ferroniobium and other

There is a method of recycling (Recycling process of chlorination of loparite // non-ferrous metallurgy, 1987, No.1, p.32-33) radioactive waste - waste molten salt irrigation filter chlorination process loparite concentrates, which consists in leaching of the melt through the drain into the water, stirring chloride slurry with a solution of barium chloride, sulfuric acid, heating the pulp and supply of steel is ticking for the purpose of recovery of trivalent iron to divalent and raising the pH to 2.5 to 3.5; the treatment of the pulp with the milk of lime to a pH of 4.5 to 5.0, and then with 0.5%solution of polyacrylamide, filtering and washing the precipitate, drying the precipitate and subsequent removal and burial in store special waste (HSO).

There is a method allows to increase the degree of concentration of thorium and its contents in the “cake”that is sent to landfill; however, the degree of extraction of thorium from the solution in the sediment - radioactive cake - over 99.9%.

For reasons that impede the achievement of specified following technical result when using the known method is unsatisfactory degree of decontamination solutions due to the high radioactivity of the effluent after separation of thorium sludge.

Known analogues of the closest to the technical essence and the achieved result for the proposed method is a known method of disposal of radioactive waste (Concentration of chloride waste processing of loparite concentrates of // non-ferrous metals, 1985, No. 2, p.53-56), which is selected as a prototype.

According to the prototype of the original radioactive waste is dissolved, the resulting solution (slurry) is treated with a solution l2, sulfuric acid and lime milk, followed by filtration of the slurry, separating the mother liquor from oxyhydrate su is hatago sludge and its disposal in store special waste. There is a method allows to localize the thorium and take it easy for long-term storage (in store special waste) form.

The disadvantage of the prototype method is unsatisfactory degree cleaning - decontamination from daughter nuclides number of thorium-232, in particular from Ra-224 and Ra-228, which is connected with incomplete coprecipitation of radium with precipitation of barium sulphate, calcium and metal oxyhydrates. Another disadvantage of the prototype method is associated with the need of transporting radioactive fallout (Chekov) in store special waste (HSO), the construction and operation of which requires large capital expenditures.

The claimed technical solution aimed at addressing the challenge in improving the environmental and radiation safety.

The technical result that can be obtained by carrying out the claimed invention is to reduce the radioactivity of the effluent after separation of the radioactive Chekov by increasing the extent of coprecipitation of natural radionuclides of the number of Th-232, in particular Ra-224 and Ra-228, with the fallout - cakes, as well as in the localization of radioactive elements (thorium and the products of its decay) and their conversion to radiation safe form water-insoluble non-dusting utverjdenie state, resistant to atmospheric precipitation, g is antovich and groundwater, not having a harmful effect on the health of the public and workers, and is suitable for further storage without causing ecological damage to the environment.

This technical result, when carrying out the claimed method, is achieved in that in the method of processing and decontamination of waste, the production of rare metals, including dissolution of obtaining the source of chloride solutions or slurries, treatment with barium chloride, sulfuric acid and lime milk, separating the precipitate from the solution, the peculiarity lies in the fact that the original chloride solution or slurry is neutralized with lime milk to pH 9-10 in the number of 120-150% of the stoichiometrically required to precipitate oxyhydrate sediment from the amount of metal oxyhydrates received oxyhydrate the slurry is filtered, the filtrate is injected barium chloride in an amount of 0.4-1.8 kg BaCl21 kg l2, present in the original solution or pulp, and pre-diluted in 5-20 times waste sulfuric acid chlorine compressors in the amount of 0.5-2.5 kg H2SO41 kg BaCl2in the resulting sulphate pulp consistently give the milk of lime to a pH of 11-12, and then the acid chloride wastewater from washing of equipment and production areas with a ratio of pulp : runoff = : (2-3) to pH 6,5-8,5, the resulting slurry was filtered and decontaminated solution discharged into the sewer, sulfate precipitate containing sulfates of barium, calcium and oxysulfate iron, mixed with oxyhydrate sludge from neutralization of the initial solution or slurry, the resulting pasty mixture is injected under continuous stirring inert filler and 0.5-2 wt. part of the calcium sulfate, the resulting composition is placed in a mold, maintained at 20-60°C for 12-36 hours and molded into blocks, which surface is then treated with water-repellent material.

The peculiarity lies in the fact that the mixture of oxyhydrate and sulphate precipitation is carried out directly on the filter press by filtration oxyhydrate pulp through a layer of sulphate precipitate, obtained from processing the previous batch.

The peculiarity lies in the fact that as the inert filler used waste containing calcium carbonate.

The peculiarity lies in the fact that as the inert filler is used precipitation and sludge treatment facilities of the companies.

The peculiarity lies in the fact that as the inert filler using wood sawdust.

The peculiarity lies in the fact that the inert filler is mixed with a mixture of sulphate and oxyhydrate precipitation ratio (0.5 to 2):1.

The peculiarity lies in the fact that calcium sulphate is used anhydrite - waste and/or nicobariensis plaster.

The peculiarity lies in the fact that, as a water-repellent material use waste paint and varnish materials.

The sequence of implementation activities and operations proposed method is illustrated by the concept presented in the drawing.

Under other equal conditions, the proposed method is characterized by new techniques of performing actions and the new order of execution of actions, the use of certain substances, without which it is impossible the implementation of the method, the new modes and parameters of the process, ensures the achievement of the technical result in the implementation of the claimed invention.

Check the patentability of the claimed invention shows that it corresponds to inventive step, as it is not necessary for professionals explicitly.

The analysis of the prior art indicates that in book, journal and patent literature contains no information about recycling and decontamination of waste, the production of rare metals by sequential processing of initial solution (slurry) first lime milk, then after separation of exigi the military precipitate with barium chloride, spent sulphuric acid chlorine compressors in the amount of 0.43-2.6 kg N2SO41 kg l2then the introduction of the milk of lime slurry, acid chloride wastewater from washing of equipment and production areas with a ratio of pulp : runoff = 1 : (2-3), filtering the slurry, a mixture of radioactive sludge with an inert filler, gypsum binder and receiving units.

Analysis of the totality of the features of the claimed invention and achieved technical result shows that between them there is a causal relationship, which is expressed in the fact that the process of recycling and decontamination of waste, the production of rare metals in strictly defined above conditions, modes, and parameters of the process: the sequence of operations, the availability of new activities, the introduction of certain substances, as defined by the ratio of reagents and a well-defined procedure for the introduction of reagents, provide a higher degree of deactivation due to the decrease in the radioactivity of the effluent after separation of the radioactive fallout at the expense of increasing the degree of co-precipitation of natural radionuclides of the number of Th-232, in particular Ra-228 and Ra-224, hydrate, sulfate and oxysulfate precipitation - cakes, localization of radioactive metal and transfer them in an environmentally safe form - non-dusting water-insoluble utverjdenie state, resistant to atmospheric precipitation, ground and underground waters, not having a harmful effect on the health of the public and workers, and is suitable for further storage without causing environmental and radiation damage to the environment.

For violations of the above ratios of the reagents, a well-defined procedure for the introduction of reagents, mixing, process conditions, sequence, etc. of the above technical result is not achieved.

It should be noted that established a causal relationship is not obvious for specialists and not derived from literature data on the chemistry and technology of rare metals.

Information supporting the implementation of the present invention to provide the above technical result, and comparing the effectiveness of known (the prototype) and the proposed technical solutions described in the example.

Example

As radioactive waste, the production of rare metals to conduct experiments were used exhaust melts saline irrigation filter chlorination process loparite concentrates.

Radioactive environment, the water, contains, wt%: 2,5 ThCl4, 20 ll3, 7 Lnl3and impurities TiCl4, NbCl3, TaCl5, NaCl, KCl, MgCl2, CaCl2, water-insoluble residue (5%), was dissolved in water at W:T=4:1. With the obtained chloride pulp comparative trials on the effectiveness of decontamination and to determine the effectiveness of known (prototype) and the proposed method.

To a known method the slurry was heated to 75±5°and treated With 200 l of 10%aqueous solution of barium chloride and 50 l of 78%sulfuric acid solution, and then neutralized with calcium hydroxide to pH 8.0±0.5, it was filtered on a plate and frame filter press. In the filtrate measured αradioactivity, and then again sent for decontamination according to the described scheme. The process of decontamination were thus 6 times before reaching the radioactivity of the filtrate 1 EQ-mg thorium/DM3.

In the proposed method the pulp was treated with lime milk to pH 9,0±0,5 valicenti 130% of the stoichiometric required for the deposition amount of the metal oxyhydrates and filtered to frame filter press. The mother solution-the filtrate was treated with 50 DM310%-aqueous solution of barium chloride and 10 DM310%-aqueous solution of spent sulphuric acid chlorine compressors, after which the pulp was treated with lime milk to a pH of 11.5±0,5 introduced 2 m3the acid chloride with the shackles from washing equipment and production sites to pH 7.0±0.5 in. Thus obtained slurry was filtered, the filtrate measured αradioactivity and dumped into the sewer. Fallout - oxyhydrate and oxysulfate - mixed, the resulting pasty mixture was injected under continuous stirring, 1 mass. part of the calcium sulfate, after which the resulting composition was placed in a mold, kept at 40°C for 20 hours and molded into blocks. The surface thus obtained blocks were treated water-repellent material - waste paint and varnish materials.

Research and testing has shown that the process of recycling of rare metals according to the proposed method makes it possible to deactivate RAO to established standards, and transfer of radioactive Chekov in utverjdenie the state provides for its environmentally sound storage without causing damage to the environment, public health and staff: obtained in accordance with the proposed method "blocks", as shown by tests that are resistant to fluctuations in ambient temperature (-50 to +50° (C), no dust, vodorastvorimyi and resistant to atmospheric precipitation, groundwater and groundwater.

1. Method of recycling rare and redkozemel what's metals, including their dissolution by obtaining initial chloride solutions or slurries, treatment with barium chloride, sulfuric acid and lime milk, separating the precipitate from the solution, wherein the source of chloride solution or slurry is neutralized with lime milk to pH 9-10 in the number of 120-150% of the stoichiometrically required to precipitate oxyhydrate sediment from the amount of metal oxyhydrates received oxyhydrate the slurry is filtered, the filtrate is injected barium chloride in an amount of 0.4-1.8 kg l21 kg CaCl2present in the original solution or pulp, and pre-diluted in 5-20 times waste sulfuric acid chlorine compressors in the amount of 0.5-2.5 kg H2SO41 kg BaCl2in the resulting sulphate pulp consistently give the milk of lime to a pH of 11-12, and then the acid chloride wastewater from washing of equipment and production areas with a ratio of pulp :runoff = 1:(2-3) to a pH of 6.5 to 8.5, the resulting slurry was filtered and decontaminated solution discharged into the sewer, sulfate precipitate containing sulfates of barium, calcium and oxysulfate iron, mixed with oxyhydrate sludge from neutralization of the initial solution or slurry, the resulting pasty mixture is injected under continuous stirring inert filler and 0.5 to 2 parts by weight of calcium sulphate, recip is nnow composition is placed in a mold, maintained at 20-60°C for 12-36 hours and molded into blocks, which surface is then treated with water-repellent material.

2. The method according to claim 1, characterized in that the mixture of oxyhydrate and sulphate precipitation is carried out directly on the filter press by filtration oxyhydrate pulp through a layer of sulphate precipitate, obtained from processing the previous batch.

3. The method according to claim 1, characterized in that as the inert filler used waste containing calcium carbonate.

4. The method according to claim 1, characterized in that as the inert filler is used precipitation and sludge treatment facilities of the companies.

5. The method according to claim 1, characterized in that as the inert filler using wood sawdust.

6. The method according to claim 1, wherein the inert filler is mixed with a mixture of sulphate and oxyhydrate precipitation ratio (0.5 to 2):1.

7. The method according to claim 1, characterized in that calcium sulphate is used anhydrite - waste and/or nicobariensis plaster.

8. The method according to claim 1, characterized in that as the water-repellent material use waste paint and varnish materials.



 

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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

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FIELD: chemical technology; recovery of deactivated and decontaminated radioactive industrial wastes.

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EFFECT: reduced radioactivity of filtrates upon separation of radioactive cakes due to enhanced coprecipitation of natural radionuclides.

7 c, 1 ex

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10 cl, 1 ex

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4 cl, 1 tbl, 12 ex

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6 cl, 1 tbl

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4 cl, 3 tbl, 5 ex

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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

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