JP2015137962A - Processing method and processing apparatus of bottom sediment containing radioactive substance - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method and an apparatus in which radioactive cesium contained in bottom sediment is efficiently removed.SOLUTION: A processing method of bottom sediment containing radioactive substance comprises: a dredging process 2 of dredging bottom sediment containing radioactive substance; a classification process 3 of classifying dredged soil D into coarse granular soil C and fine granular soil F; and a heat treatment process 5 of performing heat treatment to the fine granular soil F to vaporize radioactive cesium contained in the fine granular soil. In a method and an apparatus in which radioactive cesium contained in bottom sediment is efficiently removed, organic substance O contained in the dredged soil is separated before classification or in the classification process and the substance is used as fuel in the heat treatment process, by which radioactive cesium contained in the organic substance is also vaporized, radioactive cesium vaporized and recovered in the processes is cooled down and recovered as concentrated salt, the concentrated salt is washed in water, and radioactive cesium contained in solution obtained by the washing is adsorbed to adsorbent and recovered.

Description

  The present invention relates to a method and an apparatus for treating sediments contaminated with radioactive substances such as radioactive cesium in an accident at a nuclear power plant or the like.

  As a result of this nuclear power plant accident, a huge amount of radioactive material was released into the environment, resulting in soil and sewage sludge being contaminated by radioactive materials such as radioactive cesium and radioactive strontium. Development of technology to decontaminate radioactive materials is underway.

  In the vicinity of the stricken area, radioactive substances such as radioactive cesium from mountain forests flow and accumulate in rivers and lakes due to rainfall, so the bottom of the seabed, lake bottom, riverbed, etc. contains a huge amount of radioactive substances. It is expected that. In fact, high concentrations of radioactive materials have been confirmed in the sediments of the Fukushima Daiichi nuclear power plant, surrounding dam lakes, and reservoirs. If the sediment containing these radioactive substances leaks from the port, etc. to the open ocean, or from the lakes, etc. to the downstream area, it will cause further environmental pollution. It needs to be removed well.

  However, since the seabed and the lake bottom are large, a large-scale decontamination facility is required, and the working environment is harsh compared to the land, so that there is a problem that decontamination work is not easy.

  Therefore, the present invention has been made in view of the above-described problems in the prior art, and an object thereof is to efficiently remove a large amount of radioactive substances contained in sediment.

  In order to achieve the above object, the present invention provides a method for treating a sediment containing a radioactive substance, wherein the sediment containing the radioactive substance is dredged, and the dredged clay is classified into coarse and fine soil. The finely divided soil is heat-treated to volatilize radioactive cesium contained in the finely divided soil, and the volatilized radioactive cesium is recovered.

  According to the present invention, among the clay obtained by dripping the sediment containing radioactive material, the fine soil with high radioactive cesium content is heat treated to volatilize the radioactive cesium contained in the fine soil, and the volatilized radioactive material Since cesium is recovered, radioactive cesium contained in the sediment can be removed in a large amount and efficiently.

  Further, by removing organic substances contained in the clay before or simultaneously with the classification and using it as a fuel in the heat treatment step, radioactive cesium contained in the organic substances can be volatilized and recovered. The dyeing rate can be increased.

  The volatilized radioactive cesium is cooled to recover the concentrated salt, the recovered concentrated salt is washed with water, and the radioactive cesium contained in the solution obtained by the water washing can be adsorbed on an adsorbent and recovered. By collecting the radioactive cesium by adsorbing it on the adsorbent, the radioactive cesium does not elute even if the recovered material comes into contact with water. For example, the container for storing the recovered material only needs to be shielded and handled. Becomes easy.

  In the method for treating a sediment containing a radioactive substance, the wastewater generated in the classification is converted into a first solution having a high concentration of radioactive cesium and a second solution having a high concentration of radioactive strontium using an amphoteric ion exchange resin. Separated, the radioactive cesium contained in the first solution can be adsorbed and recovered, and the radioactive strontium contained in the second solution can be concentrated and recovered. Even when the waste water contains not only radioactive cesium but also radioactive strontium, adsorption and concentration can be performed efficiently by separating the two and treating each.

  The coarse-grained soil obtained by the classification and the fine-grained soil after volatilizing the radioactive cesium can be used as the earthwork material, and the bottom sediment after removing the radioactive substance can be effectively used.

  Furthermore, the present invention is a processing apparatus for sediment containing radioactive material, a dredging apparatus for dredging sediment containing radioactive material, and the dredged clay is treated with coarse and fine soil, or coarse grain soil. A classification device that classifies the finely divided soil into organic matter, a heat treatment device that heat-treats the classified fine soil and volatilizes radioactive cesium contained in the finely divided soil, and a recovery device that recovers the volatilized radioactive cesium. It is characterized by.

  According to the present invention, similar to the above-described invention, among the sediment containing radioactive substances, the fine soil having a high radioactive cesium content is heat treated to volatilize the radioactive cesium contained in the fine soil, and the volatilized radioactive cesium is recovered. Therefore, a large amount of radioactive cesium contained in the sediment can be efficiently removed.

  As described above, according to the present invention, a large amount of radioactive substances contained in the sediment can be efficiently removed.

It is a whole block diagram which shows one Embodiment of the processing method of the sediment containing the radioactive substance which concerns on this invention. It is the schematic which shows the classification process and contaminated water treatment process of the processing method which concerns on this invention shown in FIG. It is the schematic which shows the heat processing process of the processing method which concerns on this invention shown in FIG.

  FIG. 1 shows an embodiment of a method for treating a sediment containing radioactive substances according to the present invention. This treatment process 1 includes a dredging process 2 for dredging sediment containing radioactive substances, and a dredged clay D. Is classified into organic matter O, coarse-grained soil C, and fine-grained soil F, contaminated water treatment step 4 for treating filtrate L1 generated in classification step 3, and fine-grained soil F by heat treatment A heat treatment step 5 for volatilizing and recovering radioactive cesium contained in F (hereinafter referred to as “radioactive Cs”).

  The dredging process 2 is a process in which dredged soil D is obtained by dripping sediments such as harbors and lakes. A known method can be adopted as a method for dredging sediment, and a method for dredging is appropriately determined according to the topography, scale, geological conditions, etc. of the place where dredging is performed. For example, there are methods such as a pump rod, a grab rod, a dipper rod, etc., and one or a combination of these can be performed. In general, a large amount of radioactive Cs is contained near the surface layer of the bottom sediment, and as the amount of dredged soil increases, the burden in the subsequent classification step 3 and heat treatment step 5 increases, so that the dredging method is preferably a thin layer dredging. .

The classification step 3 is provided to classify the clay D into coarse-grained soil C such as gravel, fine-grained soil F such as silt clay, and organic matter O such as garbage, driftwood, and vegetation. The classification point is not particularly limited, and may be appropriately determined according to the content of radioactive Cs for each particle diameter. Generally, radioactive Cs contains a large amount of silt clay. F is preferably composed mainly of particles having a particle size of less than 75 μm. The main component means that 50 to 100% by mass of particles having a particle size of less than 75 μm are contained in the finely divided soil.
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  As shown in FIG. 2, in the classification step 3, the grizzly 6 that removes the organic matter O <b> 1 from the clay D, the rod scrubber 7 that thaws the clay D discharged from the grizzly 6, and the rod scrubber 7 is discharged. The vibrating sieve 8 for removing the coarse soil C1 from the slurry S1, the water receiving tank 9 for storing the slurry S2 discharged from the vibrating sieve 8, the slurry S3 supplied from the water receiving tank 9 into the fine slurry S4 and the coarse slurry S5. And a wet cyclone 10 for classification.

  The classifying step 3 includes a spiral classifier 11 that removes coarse-grained soil C2 from the coarse-grain slurry S5 discharged from the wet cyclone 10, and a dust collector that removes organic matter O2 from the slurry S6 discharged from the spiral classifier 11. A slurry tank for storing a slurry S8 generated in the reaction tank 13 and a reaction tank 13 for reacting a flocculant or the like with the slurry S7 discharged from the dust collector 12 and the fine slurry S4 supplied from the wet cyclone 10 14, a filter press 15 that solid-liquid separates the slurry S9 discharged from the slurry tank 14 into filtrate L1 and fine soil F, and a filtrate tank 16 that stores the filtrate L1 discharged from the filter press 15. .

  In the contaminated water treatment step 4, the filtrate L1 discharged from the filtrate tank 16 has a concentration of the first solution SL1 having a high concentration of radioactive Cs and a low concentration of radioactive strontium (hereinafter referred to as “radioactive Sr”) and the concentration of radioactive Cs. The amphoteric ion exchange resin 17 that is separated into a second solution SL2 having a low radioactive Sr concentration and a first solution tank 18 and a second solution tank 19 for storing the first solution SL1 and the second solution SL2, respectively. An adsorption tower 20 that adsorbs radioactive Cs from the first solution SL1, a reverse osmosis membrane 21 that concentrates the second solution SL2 and separates it into concentrated water CW containing radioactive Sr and fresh water W3, and fresh water W3. A fresh water tank 22 for storing the waste water W4 discharged from the adsorption tower 20 is provided.

  The grizzly 6 is provided for removing the organic matter O1 from the clay D using a particle size difference with a screen or the like. Grizzly 6 is composed of wedge bars, rails, etc. arranged in parallel at an inclination angle of 35 to 45 degrees at intervals of 20 to 40 cm, and is widely used for receiving raw ore at a beneficiation factory and a crushed stone factory. .

  The rod scrubber 7 mixes the clay D discharged from the grizzly 6 and the washing water W1, and uses the stirring action in the drum to defloat the clay D and adheres to the coarse-grained soil surface. It is provided for exfoliating and removing fine soil.

  The vibrating sieve 8 uses a particle size difference to remove a coarse soil C1 such as gravel having a relatively large particle size from the slurry S1, and an injection unit that is provided above the screen and injects water into the slurry S1. With. By spraying water onto the coarse-grained soil C1 on the screen from the spraying unit, the fine-grained soil F attached to the surface of the coarse-grained soil C1 is separated, and the coarse-grained soil C1 is separated and coarse particles such as sand having a relatively small particle diameter Slurry S2 containing soil C2 and fine soil F passes through the screen. The coarse-grained soil C1 having a large particle size remains on the screen without passing through the screen.

  The wet cyclone 10 uses a centrifugal force to classify the slurry S3 into a fine slurry S4 containing fine soil F and a coarse slurry S5 containing coarse soil C2 such as sand having a relatively small particle size. It is provided for separating and removing the fine soil F that adheres to the surface of the coarse-grained soil C2 due to friction between them and friction between the particles and the peripheral wall of the wet cyclone 10.

  The spiral classifier 11 is provided for classifying the slurry S5 into the coarse soil C2 and the slurry S6 containing the fine soil F by using the difference in sedimentation speed, and a screw conveyor is placed in an inclined trough having a semicircular cross section. In this case, the coarse-grained soil C2 is scraped up. The spiral classifier 11 continuously and smoothly scoops up the coarse-grained soil C2, has no mechanical problems, is easy to start, and has little disturbance of liquid in the pool.

  The amphoteric ion exchange resin 17 is made of a crosslinked polystyrene or the like as a base material, and has a function of allowing ion exchange with both cationic anions by providing a quaternary ammonium group and a carboxylic acid group in the same functional group chain. As an example, amphoteric ion exchange resin, Diaion (registered trademark), AMP03 manufactured by Mitsubishi Chemical Corporation can be used. This amphoteric ion exchange resin 17 can perform separation of the electrolyte and non-electrolyte in the aqueous solution and mutual separation of the electrolyte.

  The reverse osmosis membrane (RO membrane) 21 is a membrane that has the property of allowing water to pass through but not allowing impurities other than water, such as ions and salts, to be passed, and is practically used for desalination of seawater. The reverse osmosis membrane 21 may be a cellulose acetate membrane or an aromatic polyamide type.

  As shown in FIG. 3, the heat treatment step 5 is generated by cooling the rotary kiln 30 that heats the fine soil F to volatilize the radioactive Cs contained in the fine soil F, the cooling device 32 that cools the exhaust gas G1 of the rotary kiln 30, and cooling. The dust collector 33 for collecting the dust DU containing the concentrated salt of radioactive Cs, the water washing device 35 for washing the collected dust DU, and the radioactive Cs contained in the filtrate L2 after the water washing are adsorbed on the adsorbent A and collected. The suction device 36 and the like.

  The rotary kiln 30 is provided with an inlet for supplying fine soil F to the inside of the kiln at the bottom of the kiln, and fossil fuels such as pulverized coal and heavy oil and organic substances O1 and O2 are burned before the kiln to heat the fine soil F at high temperature. A burner is provided. By using the rotary kiln 30, the temperature suitable for volatilization of radioactive Cs and the residence time of the fine soil F can be easily adjusted.

  The cooling device 32 is provided to cool the exhaust gas G1 of the rotary kiln 30 and collect the radioactive Cs volatilized from the fine soil F in a solid state. The exhaust gas G1 is cooled by watering the exhaust gas G1 or introducing cooling air. The cooling with water and the cooling with air may be performed alone or in combination.

  The dust collector 33 is provided for recovering the dust DU containing the concentrated salt of radioactive Cs contained in the exhaust gas G2 from the cooling device 32, and a bag filter, a hepa filter, an electric dust collector, or the like can be used. From the viewpoint of preventing dust from being generated in the final exhaust gas, it is particularly preferable to use a bag filter or a hepa filter. Further, a secondary dust collector may be provided in order to adsorb and remove acid gas and the like contained in the exhaust gas G3 after removing the dust DU containing the concentrated salt of radioactive Cs. A fan 34 for discharging the exhaust gas G3 to the outside of the system is provided at the subsequent stage of the dust collector 33.

  The water washing apparatus 35 adds the demineralized water W6 to the dust DU to generate a slurry S10, dissolves the concentrated salt of radioactive Cs contained in the dust DU in water, and the slurry S10 supplied from the dissolving tank 37. And a filter press 38 for solid-liquid separation into filtrate L2 and cake CA2. A belt filter or the like can be used instead of the filter press 38.

  The adsorbing device 36 has an adsorbing tank 39 that adsorbs and collects radioactive Cs contained in the filtrate L2 separated by the filter press 38 on an adsorbent A such as Prussian blue, and radioactive contained in the filtrate L3 from the adsorbing tank 39. A sedimentation tank 40 for precipitating the adsorbent A etc. adsorbing Cs, a filter 41 for filtering the filtrate L4 from the sedimentation tank 40, and a chemical solution for removing heavy metals contained in the filtrate L5 from the filter 41 A reaction tank 42, a filter press 43 for solid-liquid separation of the filtrate L6 from the chemical reaction tank 42, a sand filter 44 for further filtering solid matter remaining in the filtrate L7 from the filter press 43, and a sand filter 44 and the resin 45 that adsorbs radioactive Cs and the like remaining in the filtrate L8.

  The adsorption tank 39 collects the radioactive Cs contained in the filtrate L2 separated by the filter press 38 by adsorbing it to the adsorbent A, and adds the coagulating sedimentation agent B to adsorb the adsorbent A adsorbing the radioactive Cs. Provided to let you. As the adsorbent A, Prussian blue, zeolite, bentonite or the like can be used, and as the coagulating sedimentation agent B, polyvinyl chloride, sodium carbonate, slaked lime, ferric sulfate or the like can be used.

  The chemical reaction tank 42 is provided to remove heavy metals contained in the filtrate L5 from the filter 41. The chemical reaction tank 42 sulfidizes heavy metals such as lead to produce precipitates such as lead sulfide, and agglomerates them. Selenium in the liquid L5 is reduced.

  The filter press 43 is provided to separate the filtrate L6 from the chemical reaction tank 42 into the filtrate L7 and the cake CA3, and to separate precipitates such as lead sulfide and selenium from the filtrate L6 to the cake CA3 side. It is done.

  The resin 45 supports Prussian blue in the pores of a porous body such as silica gel particles or ion exchange resin, and is used by adsorbing radioactive Cs remaining in the filtrate L8 from the sand filter 44. . Instead of the porous material, the column may be filled with inorganic beads such as Prussian blue and an oxide such as an oxide and kneaded and heated, and a cotton cloth colored with Prussian blue nanoparticle dispersion may be used. A non-woven fabric woven with Prussian blue may be used during production. Furthermore, reusable molecular recognition adsorbents (used by Takuma Co., Ltd. under the trade name: t-RECs (Terex)) and the like can also be used.

  Next, the processing method of the sediment containing the radioactive substance which concerns on this invention is demonstrated, referring centering on FIG.2 and FIG.3.

  First, a sediment D is obtained by thinly layering a sediment having a depth of about 20 cm in a lake or the like. The obtained clay D is supplied to the grizzly 6 to remove the organic matter O1. The clay D after removing the organic matter O1 is supplied to the rod scrubber 7. The removed organic substance O1 is supplied to the rotary kiln 30 to be used as fuel, and the incineration ash generated by the incineration treatment of the organic substance O1 can be supplied to the rotary kiln 30 as a raw material in the same manner as the fine grain soil F.

  The clay D supplied to the rod scrubber 7 is washed with the washing water W 1, and the generated slurry S 1 is supplied to the vibrating sieve 8. While supplying the washing water W2 to the vibrating sieve 8 and washing the slurry S1, the coarse-grained soil C1 remaining on the screen in the vibrating sieve 8 is removed. The slurry S2 that has passed through the screen is stored in the water receiving tank 9. The coarse-grained soil C1 can be used for earthwork materials such as concrete aggregate, roadbed material, embankment material, and embedding material. When the concentration of radioactive Cs contained in the coarse-grained soil C1 is high, the coarse-grained soil C1 can be supplied to the rotary kiln 30 to volatilize the radioactive Cs, and then used as an earthwork material.

  The slurry S3 discharged from the water receiving tank 9 is supplied to the wet cyclone 10 for wet classification, the coarse slurry S5 obtained by the wet classification is supplied to the spiral classifier 11, and the fine slurry S4 is supplied to the reaction tank 13. The coarse particle slurry S5 is classified in the spiral classifier 11 to remove the coarse particle soil C2. Coarse-grained soil C2 can be used as an earthwork material in the same manner as coarse-grained soil C1, and when the concentration of radioactive Cs contained in coarse-grained soil C2 is high, it is supplied to rotary kiln 30 to volatilize radioactive Cs. It can be used later for earthwork materials. The slurry S6 after the coarse soil C2 is removed is supplied to the dust collector 12 to remove the organic matter O2. The removed organic substance O2 can be supplied to the rotary kiln 30 as a fuel in the same manner as the organic substance O1, and the incineration ash generated by the incineration treatment of the organic substance O2 can be supplied to the rotary kiln 30 as a raw material.

  The slurry S7 discharged from the dust collector 12 is supplied to the reaction tank 13, mixed with the fine slurry S4 supplied from the wet cyclone 10, and then added with a flocculant and reacted. The slurry S8 generated by this reaction is stored in the slurry tank 14, and then supplied to the filter press 15.

  In the filter press 15, the slurry S9 is solid-liquid separated into the filtrate L1 and the fine soil F (cake). The fine soil F (cake) is supplied to the rotary kiln 30, and the filtrate L1 is supplied to the amphoteric ion exchange resin 17.

  Even when the filtrate L1 contains not only radioactive Cs but also radioactive Sr in the filtrate L1, adsorption and concentration can be efficiently performed by separating the two and treating each. By supplying the filtrate L1 to the amphoteric ion exchange resin 17, a first solution SL1 having a high concentration of radioactive Cs and a low concentration of radioactive Sr and a second solution having a low concentration of radioactive Cs and a high concentration of radioactive Sr Separated into SL2. The first solution SL1 and the second solution SL2 are stored in the first solution tank 18 and the second solution tank 19, respectively.

  The first solution SL1 is supplied to the adsorption tower 20, and the radioactive Cs contained in the first solution SL1 is recovered and the waste water W4 is discharged. The cake CA1 containing the collected radioactive Cs adsorbate can be heat-treated with the rotary kiln 30 in the same manner as the fine grain soil F. Moreover, when cake CA1 contains radioactive Cs of high concentration so that purification | cleaning by heat processing is difficult, it stores in the container (concrete cube, drum etc.) which has shielding properties. On the other hand, the 2nd solution SL2 is supplied to the reverse osmosis membrane 21, and it isolate | separates into the concentrated water CW and the fresh water W3 which radioactive Sr concentrated. The fresh water W3 and the waste water W4 are stored in the fresh water tank 22, and the wash water W5 from the fresh water tank 22 is used as the wash water W1 for the rod scrubber 7 and the wash water W2 for the vibrating sieve 8. Note that water can be newly added to the cleaning water W5 as necessary.

  In FIG. 3, the fine soil F supplied to the rotary kiln 30 is heat treated to volatilize the radioactive Cs contained in the fine soil F and the exhaust gas G <b> 1 containing the volatilized radioactive Cs is cooled by the cooling device 32. The fine soil F after the radioactive Cs is volatilized is supplied to the clinker cooler 31 and cooled, and the product P is discharged.

  The cooled exhaust gas G <b> 2 is supplied to the dust collector 33, and the dust DU containing the radioactive Cs concentrated salt that has been cooled and solidified is recovered and supplied to the dissolution tank 37. On the other hand, the exhaust gas G3 discharged from the dust collector 33 is released into the atmosphere via the fan 34.

  Next, a predetermined amount of demineralized water W6 is added to the dust DU in the dissolution tank 37 and stirred to produce a slurry S10. The slurry S10 discharged from the dissolution tank 37 is solid-liquid separated into the filtrate L2 and the cake CA2 by the filter press 38, and the radioactive Cs concentrated salt contained in the dust DU is recovered in the filtrate L2. When the radioactive Cs contained in the cake CA2 remains above the clearance level, it is preferably returned to the kiln bottom of the rotary kiln 30 and reheated. Moreover, the amount of radioactive Cs contained by washing the cake CA2 with water again can be reduced. On the other hand, when the radioactive Cs contained in the cake CA2 is not more than the clearance level, it can be used as a filler or the like, and can also be used as an earthwork material such as a buried material after being dried.

  After the adsorbent A is added to the filtrate L2 separated by the filter press 38 in the adsorption tank 39 and stirred for a predetermined time, the coagulating sedimentation agent B is added to coagulate and precipitate the adsorbent A containing radioactive Cs. Then, the radioactive Cs is roughly removed by collecting in the sedimentation tank 40 and the filter 41. When Prussian blue is used as the adsorbent A, it is necessary for the filtrate L3 after the treatment to satisfy the cyan drainage standard, so it is necessary to coagulate and precipitate Prussian blue itself. By mixing sodium carbonate and slaked lime to obtain the coagulation sedimentation agent B, the coagulation sedimentation of Prussian blue itself becomes possible.

Next, a sulfurizing agent such as sodium hydrosulfide (NaSH) is added to the filtrate L5 from the filter 41 after roughly removing radioactive Cs in the chemical reaction tank 42, and heavy metals such as lead in the filtrate L5 are added. To produce precipitates such as lead sulfide. Furthermore, after adding hydrochloric acid or the like to lower the pH, a ferrous compound or the like is added, then Ca (OH) ₂ or the like is added as an alkaline agent, and the pH is adjusted to 7.5 or more and 11 or less. The pH is optimized for the reduction of selenium, and the precipitated selenium and lead precipitates are aggregated.

  The filtrate L6 from the chemical reaction tank 42 is supplied to the filter press 43, and is solid-liquid separated into the filtrate L7 and the cake CA3, and lead sulfide, selenium, etc. contained in the filtrate L6 are separated and removed to the cake CA3 side. Radioactive Cs remaining in the filtrate L8 from the sand filter 44 is absorbed by the resin 45 and recovered. In the adsorption by the resin 45, SV10 and pH of about 8 are preferable. When the COD of the filtrate L9 discharged from the resin 45 is high, it is discharged to a river or the like after drainage treatment.

  Since the adsorbent A adsorbing the radioactive Cs collected by the sedimentation tank 40 and the resin 45 contains high concentration of radioactive Cs, it is stored in a container (concrete cube, drum can, etc.) that is not easily broken so as not to be scattered and exposed internally. When storing in large quantities, it is more preferable to store in a container having shielding properties such as a concrete container from the viewpoint of avoiding external exposure.

  As described above, according to the present embodiment, the fine soil F having a high radioactive Cs content in the clay D in the classification step 3 is heat-treated in the rotary kiln 30 to volatilize the radioactive Cs contained in the fine soil F. Therefore, the radioactive Cs contained in the sediment can be removed in a large amount and efficiently.

  In addition, before supplying the fine soil F and the coarse soil C to the rotary kiln 30, it is preferable to dry and grind them. By drying, the amount of heat consumed for evaporation of the water contained in the rotary kiln 30 becomes unnecessary, so that the amount of fuel used can be reduced. Moreover, since quality, such as radioactive Cs density | concentration, can be equalize | homogenized by grind | pulverizing, it becomes possible to remove radioactive Cs stably and reliably with the rotary kiln 30. FIG.

  Furthermore, in order to promote volatilization of radioactive Cs, a calcium source can be added. By adding a calcium source, the basicity of the fine soil F can be increased, the generation of a liquid phase in a high temperature range can be suppressed, and radioactive Cs can be volatilized efficiently. As the calcium source, calcium carbonate, quicklime, slaked lime, limestone, dolomite, blast furnace slag, and the like can be used, and one kind included in these groups can be used alone, or two or more kinds can be used in combination.

  Further, it is preferable to dry and pulverize the organic substance O before supplying it as a fuel for the rotary kiln 30. Combustibility is improved by drying and pulverization, and it can be used as a substitute for fossil fuel.

  Furthermore, the concentrated salt recovered in the heat treatment step 5 can be stored without being washed with water. In this case, it is preferable to store in a container having a sealing property and a shielding property such as a concrete container so that the recovered substance does not come into contact with water and radioactive Cs is eluted.

DESCRIPTION OF SYMBOLS 1 Treatment process of sediment containing radioactive material 2 Dredging process 3 Classification process 4 Contaminated water treatment process 5 Heat treatment process 6 Grizzly 7 Rod scrubber 8 Vibrating sieve 9 Receiving tank 10 Wet cyclone 11 Spiral classifier 12 Dust collector 13 Reaction tank 14 Slurry tank 15 Filter press 16 Filtrate tank 17 Amphoteric ion exchange resin 18 First solution tank 19 Second solution tank 20 Adsorption tower 21 Reverse osmosis membrane 22 Fresh water tank 30 Rotary kiln 31 Clinker cooler 32 Cooling device 33 Dust collector 34 Fan 35 Water washing device 36 Adsorption device 37 Dissolution tank 38 Filter press 39 Adsorption tank 40 Sedimentation tank 41 Filter 42 Chemical solution reaction tank 43 Filter press 44 Sand filter 45 Resin A Adsorbent B Aggregated sediment C1-2 Coarse soil CA1-CA3 Cake CW Concentrated water D dredged soil DU dust F fine soil G1-G3 exhaust gas L1-L9 O, O1, O2 organic P product S1 to S3, S6 to S10 slurry S4 fine slurry S5 coarse slurry SL1 first solution SL2 second solution W1, W2, W5 washing water W3 fresh W4 drainage W6 demineralized water

Claims (6)

Seduce sediment containing radioactive material,
Classifying the dredged clay into coarse and fine soil,
Heat treating the fine soil to volatilize radioactive cesium contained in the fine soil,
A method for treating a sediment containing a radioactive substance, wherein the volatilized radioactive cesium is recovered.   2. The cesium contained in the organic material is volatilized and recovered by removing the organic material contained in the clay before or at the same time as the classification and using it as a fuel for the heat treatment process. The processing method of the bottom sediment containing the radioactive substance of description. The volatilized radioactive cesium is cooled to recover the concentrated salt,
The recovered concentrated salt is washed with water,
The method for treating a sediment containing a radioactive substance according to claim 1 or 2, wherein the radioactive cesium contained in the solution obtained by the water washing is adsorbed and recovered by an adsorbent.   The wastewater generated in the classification is separated into a first solution having a high concentration of radioactive cesium and a second solution having a high concentration of radioactive strontium by using an amphoteric ion exchange resin, and the radioactive material contained in the first solution. The method for treating a sediment containing radioactive material according to any one of claims 1 to 3, wherein cesium is adsorbed and collected, and radioactive strontium contained in the second solution is concentrated and collected.   The treatment of sediment containing radioactive material according to any one of claims 1 to 4, wherein the coarse-grained soil obtained by the classification and the fine-grained soil after volatilizing the radioactive cesium are used for earthwork materials. Method. Dredging equipment that drowns sediment containing radioactive materials;
A classification device for classifying the dredged clay into coarse and fine soil, or coarse and fine soil and organic matter,
A heat treatment apparatus for heat treating the classified fine soil to volatilize radioactive cesium contained in the fine soil;
An apparatus for treating sediment containing radioactive material, comprising: a collection device for collecting the volatilized radioactive cesium.

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