JP5313387B1 - Methods for treating radioactive material contaminants - Google Patents

Abstract

The present invention provides a method and an apparatus for treating radioactive material contaminated soil that can efficiently decontaminate and reduce the amount of radioactive material contaminated soil without generating extra waste.
SOLUTION: A dry classification process for separating coarse soil having a predetermined particle size or more from a radioactive material contaminated soil that is an object to be treated, and a grinding process for scraping the particle surface of the radioactive material contaminated soil from which the coarse soil has been removed. And at least a part of the size of the nano-size in the grinding soil from which the particle surface obtained by grinding process is scraped off. The metal particles having an affinity for the ferromagnetic powder and the solidifying agent, and the nano-dispersion in which the ferromagnetic powder is dispersed in the solidifying agent are added and mixed to insolubilize the radioactive substance and make it separable. A concentration separation step, and a concentration separation step of magnetically sorting the soil after the insolubilization / concentration separation enabling step to concentrate and separate radioactive substances.
[Selection] Figure 7

Description

The present invention also relates soil contaminated with cesium, rubble, waste plastics, wood chips, the process how the contaminated contaminants radioactive material such as waste paper.
In the present invention, radioactive material contaminants are contaminated with radioactive material-contaminated soil, radioactive material-contaminated industrial waste such as rubble, waste plastic, wood scrap, and waste paper, or radioactive material-contaminated soil and radioactive material. A mixture of radioactive debris contaminated industrial waste such as rubble, waste plastic, wood and paper, and a mixture of these and incinerated ash containing radioactive material.

  Due to the Fukushima Daiichi Nuclear Power Plant accident, which originated from the Great East Japan Earthquake, the diffusion of radioactive materials to the surrounding area has become a serious social problem. The released radioactive materials are mainly iodine (I) 131, cesium Cs134, and Cs137. However, since I131 has a short half-life of 8 days, the long-term problem is considered to be Cs134 with a half-life of about 2 years and Cs137 with a half-life of about 30 years.

The radioactive Cs (zero value) immediately after emission from the nuclear power plant instantly becomes oxides and carbonates, and gradually changes to hydroxides due to their deliquescence. The kind of counter anion does not affect the solubility of Cs, which is an alkali metal. Therefore, in any form, radioactive Cs in the atmosphere is transferred to an aqueous phase such as raindrops as Cs ⁺ and causes soil contamination by rainfall.

  On the other hand, the existence form of radioactive Cs in the soil can be broadly classified as follows: (1) ion adsorption on organic substances such as humic substances, (2) ion adsorption on the surface of soil particles, and (3) trapped inside layered minerals such as clay. It is classified as a thing. In short, it becomes adsorbed on the soil surface or adsorbed inside the layered structure of the soil. The radioactive Cs of (1) and (2) is also stabilized as (3), but the migration rate depends on the amount of coexisting organic substances and cannot be clearly predicted. In fact, according to the materials reported to the Atomic Energy Commission (34th Atomic Energy Commission Material No. 1), even today, more than half a year after the accident, most of the radioactive Cs was found on the soil particle surface.

In addition, radioactive Cs inside the layered structure is relatively stable, but supply of high concentrations of K ⁺ and NH ₄ ⁺ and divalent cations (snow melting agent, weakly acidic Ca ^{2+ in} acid rainwater, etc.) by fertilization Under such complex factors, there is a possibility of re-elution of radioactive Cs. Since the eluted radioactive Cs increases the risk of being absorbed by humans, it is desirable to make the radioactive Cs insoluble as stably as possible for a long period of time.

  Existing soil treatment technologies were only phytoremediation and cement solidification by sunflower. As a result of the demonstration test, the former has almost no effect, and the latter has many problems in solidifying contaminated soil with salt and oil pollution caused by tsunami damage.

  Recently, diversion of existing heavy metal processing technology has been attempted, and typical examples thereof include a washing / sieving method (Kyoto Univ .: Associate Professor Toyohara et al., Asahi Shimbun 20111.8.17, for example, Non-Patent Document 1), cellulosic Solidification with polyion (PIC) method (used in Chernobyl accident), acid extraction / bitumen adsorption method (AIST: Yase, Head of Nanosystem Research Division et al., Press release 2011.8.31, see Non-Patent Document 2, for example), water washing / Clay adsorption method (Tohoku University: Prof. Ishii et al., Nuclear Committee Regular Meeting Material 2011.9.6), Bitumen Direct Adsorption Method (Tokyo Tech: Prof. Arisu et al., NTV 2011, 4.20, see Non-patent Document 3, for example) ) Etc. In addition, many decontamination technologies have been introduced as “Decontamination Technology Demonstration Test Project” in 2011 (see Non-Patent Document 4, for example).

  The present inventors have developed a nanocalcium method for treating contaminated soil in a dry manner using nanocalcium (see, for example, Non-Patent Document 5), and a patent is pending. The nano calcium method is a method in which a nano dispersion in which nano-sized metallic calcium is dispersed in calcium oxide is added to and mixed with contaminated soil to insolubilize radioactive Cs. Furthermore, if a nano-dispersion added with iron powder is used, the radioactive substance can be concentrated and separated by magnetic separation.

http://www.asahi.com/science/update/0816/OSK201108160253.html http://www.aist.go.jp/aist_j/press_release/pr2011/pr20110831/pr20110831.html www.news24.jp/articles/2011/04/20/07181347.html www.aec.go.jp/jicst/NC/iinkai/teirei/siryo2012/siryo12/siryo1-3.pdf http://c-collabo.jp/act/img/nplan/cch23/rp_ic(2)_1.pdf

  However, the processing method has a problem. For example, the water washing / sieving method, the PIC method, and the clay adsorption method require a large amount of water for Cs washing in the soil and require waste liquid treatment, and further, sieving of the hydrous clay is difficult. The coagulant is added to the waste to increase waste, the acid extraction method is expensive due to the use and neutralization of highly corrosion-resistant equipment, and the bitumen direct adsorption method generates cyanide gas by ultraviolet decomposition. There is a possibility of doing. Most of the decontamination technologies introduced as “Decontamination Technology Demonstration Test Project” in 2011 use water, and wastewater treatment is required.

  The nano-calcium method developed by the present inventors is excellent in that radioactive Cs can be insolubilized by adding and mixing a small amount of nano-dispersion to contaminated soil, and that radioactive substances can be concentrated and separated by magnetic separation. Although the method is applied to the treatment of a large amount of contaminated soil, the amount of the nanodispersion that is a drug is inevitably increased. In order to treat a large amount of contaminated soil at a low cost, it is necessary to develop a treatment process that can efficiently treat a small amount of chemicals.

An object of the present invention is to provide a process how extra waste decontaminate efficiently radioactive contaminants without generating and radioactive materials contaminants capable of volume reduction.

In the present invention, the radioactive material contaminants to be treated are dry classified, and the concentration of radioactive material is lower than the predetermined size, and the concentration of radioactive materials is lower than the predetermined size. In a method for treating radioactive material contaminants, which are separated into high-concentration contaminants having a high size less than a predetermined size and decontaminating the radioactive material contaminants to be treated by removing the high-concentration contaminants ,
Prior to the dry classification, an adsorbent capable of suppressing the aggregation and solidification of radioactive material contaminants and preferentially adsorbing small radioactive material contaminants is added to and mixed with the radioactive material contaminants to be treated. A small radioactive substance contaminant is adsorbed on an adsorbent, and the adsorbent adsorbing the radioactive substance contaminant of less than a predetermined size and the radioactive substance contaminant is separated as the high-concentration contaminant in the dry classification. This is a method for treating radioactive material contaminants.

  In the method for treating radioactive material contaminants according to the present invention, the adsorbent is a combustible adsorbent.

In addition, the method for treating radioactive material contaminants of the present invention further includes an incineration step of incinerating the high-concentration contaminants separated by the dry classification to obtain incineration ash of the high-concentration contaminants .

Processing method for a radioactive material contamination of the invention, adding a solidifying agent to the high concentration contaminants separated by pre Symbol dry classification to further and / or the low density contaminants mixed and insoluble radioactive material An insolubilization step is included.

The method for treating radioactive material contaminants of the present invention further includes an insolubilization step of adding and mixing a solidifying agent to the incinerated ash of the high-concentration contaminants to insolubilize the radioactive material.

Further, the method for treating radioactive material contaminants of the present invention is characterized by further adding and mixing a solidification aid together with the solidifying agent to insolubilize the radioactive material.

The method for treating a radioactive pollution of the present invention is characterized in that the solidifying agent is an oxide calcium.

  The radioactive substance contaminant treatment method of the present invention is characterized in that the solidification aid is a phosphate.

The process how radioactive pollution of the present invention, the radioactive material contamination, radioactive material contaminated soil, radioactive pollution industrial waste, or a mixture of a radioactive material contaminated soil with radioactive materials contaminated industrial waste, further It is a mixture of these and incinerated ash containing radioactive substances.

The process how radioactive pollution of the invention, characterized in that the radioactive material contamination industrial waste, comprising at least rubble, waste plastics, waste wood, waste paper, or one or more any of these crushed And

By using the method for treating radioactive material contaminants of the present invention, it is possible to efficiently decontaminate and reduce the amount of radioactive material contaminants without generating extra waste .

It is a flowchart which shows the process sequence of the radioactive material contamination soil of 1st Embodiment of this invention. It is the figure which showed the particle size distribution of the classified radioactive material contamination soil. It is the figure which showed the relationship between the particle size of the radioactive substance contaminated soil classified, and the amount of radioactivity. It is a flowchart which shows the process sequence of the radioactive material contamination soil of 2nd Embodiment of this invention. It is a flowchart which shows the process sequence of the radioactive material contamination soil of 3rd Embodiment of this invention. It is a flowchart which shows the process sequence of the radioactive material contamination soil of 4th Embodiment of this invention. It is a flowchart which shows the process sequence of the radioactive material contamination soil of 5th Embodiment of this invention. It is a process flowchart which shows the structure of the processing apparatus 1 of the radioactive material contaminated soil which can implement the processing method of the radioactive material contaminated soil of 5th Embodiment of this invention. It is a schematic diagram for demonstrating the insolubilization / concentration separation possible mechanism (assuming) in the processing method of radioactive substance contaminated soil of 5th Embodiment of this invention. In the processing method of the radioactive material contaminated soil of 5th Embodiment of this invention, it is a schematic diagram for demonstrating the mechanism (presumption) which physically concentrates and isolates the radioactive substance contained in the soil in which the insolubilization and concentration separation possible processing were carried out. is there. It is a figure which shows the particle size distribution of the nano dispersion used in the Example of this invention.

  In the method and apparatus for treating radioactive material contaminants of the present invention, radioactive material-contaminated soil, radioactive material-contaminated industrial waste such as rubble, waste plastic, wood scrap, and waste paper contaminated with radioactive material, or radioactive material-contaminated soil And a mixture of the radioactive material-contaminated industrial waste, and a mixture of these and incinerated ash containing the radioactive material are treated materials. For this reason, in addition to soil contaminated with radioactive substances, debris, waste plastic, wood scraps, paper scraps and the like contaminated with radioactive substances can be decontaminated and reduced in volume.

  Hereinafter, specific embodiments will be described in which radioactive material-contaminated soil is treated, but the present invention is not limited to radioactive material-contaminated soil as described above, but is also a radioactive material-contaminated industry such as rubble, waste plastic, wood waste, paper waste, etc. In the embodiment shown below, in place of radioactive material contaminated soil, radioactive material contaminated industrial waste, a mixture of radioactive material contaminated soil and radioactive material contaminated industrial waste, etc. are used. It can be processed in a similar manner.

  FIG. 1 is a flowchart showing a processing procedure for radioactive material-contaminated soil according to the first embodiment of the present invention. In the method for treating radioactive material-contaminated soil according to the first embodiment of the present invention, radioactive material-contaminated soil having a particle size less than a predetermined particle size is separated from the radioactive material-contaminated soil that is the object to be treated by dry classification, Decontaminate.

  The radioactive material-contaminated soil that is the object to be treated is not limited to a specific soil. Moreover, the radioactive substance which is a pollutant is not limited to a specific substance, but can cover a wide range of radioactive substances such as cesium Cs, plutonium Pu, uranium U, and radium Ra.

  When the moisture in the radioactive substance-contaminated soil to be treated exceeds 10% by weight, prior to dry classification, the radioactive substance-contaminated soil is dried to make the moisture in the radioactive substance-contaminated soil 10% by weight or less. A preferable water content is 1 to 5% by weight. When the moisture in the radioactive material contaminated soil exceeds 10% by weight, the radioactive material contaminated soils are aggregated, or the radioactive material contaminated soil having a small particle size is likely to adhere to the radioactive material contaminated soil having a large particle size. In particular, soil with a small particle size tends to agglomerate and adhere. Therefore, dry classification of radioactive material-contaminated soil whose water content exceeds 10% by weight is not preferable because it cannot sufficiently classify soil with a small particle size.

  As long as the dry classification can be classified to a predetermined particle size, the classification method and the apparatus type are not particularly limited. It goes without saying that it is preferable to use a dry classifier having high classification efficiency, low cost and high processing speed. A dust collector may be provided if necessary. As dry classifiers, sieves, vibrating sieves, gravity classifiers (wind classifiers), centrifugal classifiers such as cyclones, and inertia classifiers such as louver classifiers can be used. It can be selected as appropriate in consideration.

  2 and 3 are diagrams showing classification of radioactive material-contaminated soil, measurement of the amount of radioactivity for each particle size, and the relationship between the particle size distribution and the particle size of the radioactive material-contaminated soil and the amount of radioactivity. Table 1 shows the concentrations of Cs137 and Cs134 in the radioactive material-contaminated soil according to particle size.

  As shown in FIG. 2, radioactive material-contaminated soil has a large particle size of 0.5 to 2 mm, but Cs137 and Cs134 are also contained in a large amount of soil having a particle size of 0.125 mm or less as shown in FIG. As shown in Table 1, the smaller the particle size, the higher the concentration of Cs137 and Cs134 in the radioactive material contaminated soil. On the other hand, the concentration of Cs137 and Cs134 in the soil exceeding 7 mm is very small. In the case of the radioactive material contaminated soil, if the radioactive material contaminated soil is classified with a particle size of 0.25 mm and the radioactive material contaminated soil of less than 0.25 mm is separated, the decontamination rate is 48% and the weight loss rate is 76%.

  Here, the decontamination rate is the amount of Cs137 and Cs134 contained in the separated radioactive material contaminated soil with respect to the amount of Cs137 and Cs134 contained in the radioactive material contaminated soil before classification. Further, the weight loss rate is the weight of the radioactive material contaminated soil remaining with respect to the weight of the radioactive material contaminated soil before classification, in this case, the weight of radioactive material contaminated soil of 0.25 mm or more.

  The particle size to be classified is preferably determined based on the result of sampling and classifying radioactive material-contaminated soil in advance and measuring the amount of radioactivity for each particle size. The particle size to be classified does not necessarily need to be one point, but as shown in Table 1, the concentration of Cs137 and Cs134 in the radioactive material contaminated soil increases as the particle size decreases. For example, it is efficient to classify by 0.25 mm, and to classify into contaminated soil of 0.25 mm or more and contaminated soil of less than 0.25 mm.

  As described above, the radioactive material-contaminated soil treatment method according to the first embodiment separates radioactive material-contaminated soil having a particle size less than a predetermined particle size from the radioactive material-contaminated soil that is the object to be treated by dry classification. Unlike the wet treatment method, water treatment is not necessary and can be easily carried out. Although this method cannot be said to have a sufficiently high decontamination rate, it is suitable for mass treatment because of its simple operation, and can be suitably used as a pretreatment of radioactive material contaminated soil.

  FIG. 4 is a flowchart showing a processing procedure for radioactive material-contaminated soil according to the second embodiment of the present invention. The method for treating radioactive material-contaminated soil according to the second embodiment of the present invention can preferentially adsorb radioactive material-contaminated soil having a small particle size to the radioactive material-contaminated soil that is the object to be treated, while suppressing aggregation and solidification of soil particles. The adsorbent adsorbs radioactive material-contaminated soil and radioactive material-contaminated soil having a particle size less than a predetermined particle size by adding and mixing various adsorbents, adsorbing the radioactive material-contaminated soil having a small particle size to the adsorbent, dry-classifying them. And decontaminate radioactive material contaminated soil. Description of parts common to the method for treating radioactive material-contaminated soil of the first embodiment will be omitted, and description will be made focusing on parts different from the method for treating radioactive material-contaminated soil of the first embodiment of the present invention.

  The basic concept of the method for treating radioactive material-contaminated soil according to the second embodiment of the present invention is the same as the method for treating radioactive material-contaminated soil according to the first embodiment of the present invention. Is different from the method for treating radioactive material-contaminated soil according to the first embodiment of the present invention in that after the radioactive material-contaminated soil having a small particle size is adsorbed to the adsorbent, these are dry-classified.

  As the adsorbent, a physical adsorbent that adsorbs radioactive material-contaminated soil by physical action is used. When the physical adsorbent with fine irregularities and pores on the surface and the radioactive material contaminated soil are mixed with stirring, the soil particles are prevented from coagulating and solidified, and a part of the radioactive material contaminated soil adheres to the surface of the physical adsorbent. Or, the physical adsorbent gets into the irregularities and pores. In particular, radioactive material contaminated soil with small particle size adheres to the surface of the physical adsorbent or easily enters the irregularities and pores of the physical adsorbent, so the radioactive material contaminated soil with small particle size is preferentially captured by the physical adsorbent. Is done. In general, physical adsorbents that use physical action have lower adsorption power than chemical adsorbents that use chemical action, but the adsorption rate is fast, so they can be used for large-scale treatments such as soil contaminated with this radioactive material. Is suitable.

  Further, when the adsorbent and the radioactive material contaminated soil are stirred and mixed together, they come into contact with each other, and the adsorbent acts to wipe off the surface of the radioactive material contaminated soil. Therefore, when the adsorbent and the radioactive material contaminated soil are stirred together, the radioactive material contaminated soil having a small particle size is wiped from the radioactive material contaminated soil having a large particle size.

  As shown in Table 1, since radioactive substances are contained in a large amount in radioactive substance-contaminated soil with a small particle size, removing radioactive material-contaminated soil with a small particle size is effective in increasing the decontamination rate. In general, when the particle size is small, classification becomes difficult, but in this method, radioactive material-contaminated soil with small particle size is adsorbed by the adsorbent, so the adsorbent is added to the radioactive material-contaminated soil and mixed from the viewpoint of classification. It is preferable to do.

  Since the adsorbent adsorbs radioactive substance-contaminated soil having a small particle size out of radioactive substance-contaminated soil, it is not preferable that the adsorbent has extremely large irregularities and pore diameters, or conversely extremely small. An adsorbent having irregularities and pore sizes that are easy to adsorb radioactive material-contaminated soil to be adsorbed and removed is preferable.

  The size of the adsorbent itself is not limited to a specific size, but if it is too large, the contact efficiency with the radioactive material contaminated soil is reduced, which is not preferable. A thing as small as possible within the range which can be classified easily is preferable. The amount of adsorbent added to radioactive material-contaminated soil is not particularly limited, but adding more than necessary will increase the processing time for stirring and dry classification and decrease the processing speed. It is preferable to do. Examples of the adsorbent having the above characteristics include paper, cotton, rice husk, charcoal, and zeolite.

  After adding and mixing the adsorbent to the radioactive material-contaminated soil and adsorbing the radioactive material-contaminated soil to the adsorbent, dry classification is performed in the same manner as the radioactive material-contaminated soil treatment method of the first embodiment, and predetermined. What is necessary is just to isolate | separate the adsorbent which adsorb | sucked the radioactive substance contaminated soil of less than particle size, and radioactive substance contaminated soil. Note that the dry classification is not necessarily performed with only one type of dry classifier, and naturally two or more types of dry classifiers may be used.

  By the above method, an effect equal to or greater than that of the radioactive material contaminated soil treatment method of the first embodiment of the present invention can be obtained.

  If a flammable adsorbent is used in the adsorbent, it can be recovered as incinerated ash by burning the adsorbent that has adsorbed radioactive material-contaminated soil after dry classification. Use of such a method in combination is preferable because the volume can be reduced.

  FIG. 5 is a flowchart showing a processing procedure for radioactive material-contaminated soil according to the third embodiment of the present invention. In the method for treating radioactive material-contaminated soil of the third embodiment of the present invention, dry classification (dry classification step: step S1) is performed after adding the same adsorbent as the method for treating radioactive material-contaminated soil of the second embodiment of the present invention. ), And further, the solidified agent is added to and mixed with the incinerated ash obtained by incineration of the classified radioactive material-contaminated soil with a small particle size and the adsorbent adsorbing the radioactive material-contaminated soil (incineration process: step S2). The substance is insolubilized (insolubilization step: step S3).

  Here, a flammable adsorbent is used as the adsorbent. The classification method is the same as the classification method shown in the method for treating radioactive material-contaminated soil according to the second embodiment of the present invention, and the description thereof will be omitted. Although FIG. 5 shows an example in which the radioactive material-contaminated soil having a small particle size and the adsorbent adsorbing the radioactive material-contaminated soil are classified separately, they may be in a mixed state. In this case, the classified mixture of the radioactive material-contaminated soil having a small particle size and the adsorbent is incinerated.

  In the insolubilization step, the radioactive material is insolubilized by adding and mixing the solidifying agent to the classified radioactive material contaminated soil and incinerated ash having a small particle size. The solidifying agent reacts with moisture contained in the radioactive material contaminated soil and incinerated ash, and coats the particle surface of the radioactive material contaminated soil in the process of solidifying itself. The solidifying agent is insoluble in water after solidifying. The radioactive substance-contaminated soil whose particle surface is coated with a solidifying agent is insoluble in water, so that elution of the radioactive substance can be prevented.

  The solidifying agent that exhibits the above functions is not limited to a specific solidifying agent, but is preferably solidified in a small amount and inexpensive, and calcium oxide (CaO) can be suitably used. In addition, magnesium oxide (MgO) is exemplified as the solidifying agent. A solidifying agent having a small particle size is preferred from the viewpoint of contactability and stirring and mixing properties.

  The radioactive material-contaminated soil and incineration ash that are treated in the insolubilization process contain a small amount of water, but the water contained in these is not zero, so when a solidifying agent is added, the solidifying agent is included in the radioactive material-contaminated soil, etc. Reacts with moisture. In addition, when the moisture contained in the radioactive substance contaminated soil or the like is insufficient, a small amount of water may be sprayed on the radioactive substance contaminated soil or the like before the solidifying agent is added. As the stirring and mixing apparatus, a known apparatus for stirring and mixing powders can be used.

  In the method for treating radioactive material-contaminated soil according to the third embodiment of the present invention, the solidifying agent is added to and mixed with the classified radioactive material-contaminated soil and incinerated ash, and the radioactive material is insolubilized. A solidifying agent may also be added to and mixed with the classified radioactive material-contaminated soil with a large particle size to insolubilize the radioactive material. Insolubilization of radioactive material-contaminated soil can also be suitably applied to classified small-sized radioactive material-contaminated soil, classified small-sized radioactive material-contaminated soil, and adsorbents that adsorb radioactive material-contaminated soil. Therefore, an insolubilization step may be incorporated into the radioactive material contaminated soil treatment method of the first and second embodiments of the present invention.

  In the insolubilization step, a solidification aid may be added simultaneously. The solidification aid has a function of promoting solidification of the radioactive substance-contaminated soil and preventing elution of the radioactive substance. Examples of the solidification aid that can be used here include dihydrogen phosphates such as sodium dihydrogen phosphate and potassium dihydrogen phosphate, and other phosphates. Sodium dihydrogen phosphate is preferably used. it can. Radioactive substance-contaminated soil solidified using sodium dihydrogen phosphate has been confirmed to have a neutral surface and a neutral pH of the aqueous solution. For this reason, there is a possibility that diffusion due to elution and scattering and uptake into living organisms and plants when it is temporarily placed in another place before long-term storage at a final disposal site or the like may be reduced. Even when the solidifying agent and the solidification aid are added and mixed at the same time to insolubilize the radioactive substance, it can be carried out in the same manner as when only the solidifying agent is added to insolubilize the radioactive substance.

  Adsorbed classified small-sized radioactive material contaminated soil, classified small-sized radioactive material contaminated soil and radioactive material-contaminated soil, or classified small-sized radioactive material contaminated soil and radioactive material-contaminated soil If a solidifying agent and a solidification aid are added to and mixed with the incinerated ash obtained by incinerating the adsorbent, the elution of radioactive substances can be prevented and the storage thereof becomes easy.

  In the above embodiment, combustible material such as waste plastic, wood waste, industrial waste such as waste paper, or a mixture of radioactive material contaminated soil and the radioactive material contaminated industrial waste is included in the object to be treated. If it is contained, it is preferable to add and mix a solidifying agent and a solidification aid to the incinerated ash obtained by incineration of the classified objects to be processed, thereby insolubilizing them.

  FIG. 6 is a flowchart showing a processing procedure for radioactive material-contaminated soil according to the fourth embodiment of the present invention. The processing method of radioactive substance contaminated soil of 4th Embodiment of this invention isolate | separates the coarse grain soil more than a predetermined particle size from the drying process (step S11) which dries radioactive substance contaminated soil, and the dried radioactive substance contaminated soil. It includes a dry classification process (step S12) and a grinding process (step S13) for removing the radioactive substance adhering to the radioactive substance-contaminated soil by scraping the particle surface of the radioactive substance-contaminated soil from which coarse-grained soil has been removed.

  The drying process is similar to the method for treating radioactive material-contaminated soil of the first embodiment. The radioactive material-contaminated soil with small particle size adheres to the radioactive material-contaminated soil with large particle size, and the radioactive material-contaminated soil aggregates. In order to prevent this, the water content is set to 10% by weight or less, more preferably 1 to 5% by weight, in the same manner as the method for treating radioactive material-contaminated soil of the first embodiment. If the amount of water contained in the radioactive material contaminated soil is 10% by weight or less, the drying step is unnecessary.

  A dry classification process is a process of isolate | separating coarse-grained soil more than a predetermined particle size from the dried radioactive substance contaminated soil. As shown in Table 1, radioactive material-contaminated soil has a smaller content of radioactive material as the particle size becomes larger, and the amount of radioactive material contained in coarse-grained soil exceeding 7 mm as shown in the examples below is very high. Very few. Therefore, such coarse-grained soil can be handled as low-concentration contaminated soil without decontamination.

  In addition, in the grinding process, which is a subsequent process, when using a particle grinding (grain friction) method that uses the friction between soil particles to prevent soil particle crushing and scrapes the surface of the soil particles, It is preferable that the particle size distribution of some radioactive material contaminated soil is sharp. If the particle size is uniform and the particle size distribution is sharp, the soil particles are difficult to crush during grain grinding.

  The grinding step is a step of scraping off the particle surface of the radioactive material contaminated soil from which the coarse soil has been removed, and removing the radioactive material adhering to the radioactive material contaminated soil. Since many radioactive substances contained in the radioactive material contaminated soil exist on the soil surface, the decontamination rate and the weight loss rate can be increased by scraping the surface of the radioactive material contaminated soil.

  The grinding apparatus used in the grinding step is not limited to a specific apparatus, but an apparatus capable of grinding only the surface without crushing soil particles is preferable. When the soil particles are crushed, soil particles and fine powder having a small particle size (hereinafter, soil and fine particles having a small particle size generated as the soil particles are crushed are referred to as crushed small particles) are generated. Among the crushed small particles, crushed small particles having the same size as the fine powder (grinding fine powder) generated with the grinding of the surface of the soil particles cannot be classified as the ground fine powder. Since radioactive material contained in radioactive material-contaminated soil is large on the soil surface and conversely small in the interior, the crushed small particles contain less radioactive material than ground fine powder. For this reason, if a lot of crushed small particles are generated and separated together with the grinding fine powder, the decontamination rate does not increase so much and, conversely, the weight reduction rate decreases.

  As an apparatus that grinds the surface while preventing crushing of radioactive material-contaminated soil particles, a grinding apparatus that uses particle friction to bring soil particles into contact with each other and polish each other's surface is preferable. In addition, there is also a pressure friction type device that performs particle friction in a pressurized state as a grinding device using the particle friction. As such a grinding apparatus, there are a sand recycling apparatus (Taiyo Machinery Co., Ltd.), a rice mill and the like that can regenerate cast sand and the like.

  Depending on the type and model of the grinding device that grinds the particle surface, there are some that do not have the function of separating the fine powder that is the ground material. In such a case, the fine powder is separately collected using a dry classifier or dust collector. What is necessary is just to separate.

  The method for treating radioactive material-contaminated soil according to the fourth embodiment of the present invention can be suitably used for treating radioactive material-contaminated soil having a large particle size and a relatively small concentration of radioactive material as a whole. In the case of radioactive material-contaminated soil with a large particle size, the specific surface area is small, so it can be efficiently decontaminated by scraping the soil surface. Furthermore, in combination with the radioactive substance contaminated soil treatment method according to the first or second embodiment of the present invention, only radioactive substance contaminated soil of a predetermined particle size may be used as an object to be treated in the grinding step. As a result, the amount of radioactive material contaminated soil to be ground is reduced and the soil can be treated efficiently.

  In the method for treating radioactive material-contaminated soil according to the fourth embodiment, it is preferable to insolubilize the fine powder, which is a ground material generated in the grinding step, by the insolubilization method described above. Moreover, it is preferable to insolubilize the radioactive material-contaminated soil whose surface has been cut off by the insolubilization method described above.

  FIG. 7 is a flowchart showing a processing procedure for radioactive material-contaminated soil according to the fifth embodiment of the present invention. FIG. 8 is a process flow diagram showing the configuration of the radioactive substance-contaminated soil treatment apparatus 1 capable of implementing the radioactive substance-contaminated soil treatment method of the fifth embodiment of the present invention.

  In the method for treating radioactive material-contaminated soil according to the fifth embodiment of the present invention, three steps are added to the treatment step for radioactive material-contaminated soil according to the fourth embodiment of the present invention. These three processes include a fine powder insolubilization process (step S14) in which a solidifying agent is added to and mixed with the fine powder generated in the grinding process to insolubilize the radioactive substance, and a radioactive substance contaminated soil in which the surface obtained by the grinding process is scraped ( Grinding soil) is added and mixed with chemicals to insolubilize radioactive substances and to enable concentration / separation (step S15), and to magnetically sort the soil after the insolubilization / concentration separation enabling process, This is a concentration separation step (step S16) for concentrating and separating radioactive substances.

The radioactive substance contaminated soil treatment apparatus 1 shown in FIG. 8 is a continuous treatment apparatus. Radioactive substance-contaminated soil is sent to the dryer 3 and dried to a moisture content of 10% by weight or less, preferably 1 to 5% by weight (drying step). FIG. 8 shows a rotary kiln type dryer using steam as a heating medium, but the dryer is not limited to a specific type including the heating medium,
Various dryers can be used according to the moisture content of the radioactive material contaminated soil. When dust may be discharged outside during drying, a dust collector is provided. In addition, when a radioactive substance contaminated soil having a moisture content of less than 10% by weight is used as the object to be treated, the drying step can be omitted, and thus there is no need to provide the dryer 3.

  The dried radioactive substance-contaminated soil discharged from the dryer 3 is sent to the vibrating sieve 5 to separate a predetermined coarse-grained soil (dry classification step).

  The radioactive material contaminated soil from which the coarse soil has been separated is sent to the grinding device 7 and the surface of the radioactive material contaminated soil is scraped off (grinding step). The grinding device 7 uses the grinding device described in the method for treating radioactive material contaminated soil according to the fourth embodiment of the present invention.

  The fine powder, which is a grinding product generated in the grinding process, is sent to the stirring and mixing device 9, where a solidifying agent and a solidification aid are added and mixed to insolubilize the radioactive substance (fine powder insolubilization process). Here, a solidification aid is added in addition to the solidifying agent, but only the solidifying agent may be added and mixed to insolubilize the radioactive substance. The fine powder insolubilization treatment can be performed in the same manner as the insolubilization step of the third embodiment of the present invention described above. As the stirring and mixing device 9, a known device capable of stirring and mixing powders can be used.

  On the other hand, the radioactive material contaminated soil (ground soil) whose surface has been ground in the grinding process is sent to the stirring and mixing device 11, where the nano-dispersion and the solidification aid are added and mixed as agents to insolubilize the radioactive material. And can be concentrated and separated. As the solidification aid used in the fine powder insolubilization step and the grinding soil insolubilization / concentration separation possible step, the same solidification aid as described above can be used. The solidification aid can be omitted.

  The nano-dispersion is obtained by dispersing ferromagnetic powder and at least partly nano-sized metal particles having affinity for the ferromagnetic powder and the solidifying agent in the solidifying agent. Here, the same solidifying agent as that shown above can be used as the solidifying agent.

  The ferromagnetic powder is added for magnetic selection in the next step. The ferromagnetic powder is not limited to a specific ferromagnetic powder, and a known ferromagnetic powder such as iron powder can be used. The ferromagnetic powder is preferably inexpensive, and iron powder is preferred in this respect.

  The metal particles are metal particles having an affinity for the ferromagnetic powder and the solidifying agent, and enhance the bond between the ferromagnetic powder and the solidifying agent. Without adding metal particles, it is possible to insolubilize and concentrate / separate using ferromagnetic powder and solidifying agent, or ferromagnetic powder, solidifying agent and solidification aid, but solidify with ferromagnetic powder. It is preferable to add metal particles from the viewpoint of increasing the bond with the agent and further increasing the insolubilization rate of the radioactive substance by chemical action. On the other hand, when the metal particles are not used, the cost of the medicine can be reduced. Therefore, the treatment method may be appropriately selected according to the concentration and purpose of the radioactive substance contained in the grinding soil.

  The metal particles that enhance the bond between the ferromagnetic powder and the solidifying agent and chemically act on the radioactive substance include alkali metals, alkaline earth metals such as metallic calcium, group 3 elements such as aluminum, iron and Examples include alloys containing these elements. These may be used alone or in combination, and among them, calcium metal and aluminum can be preferably used.

  The nano-dispersion can be obtained by pulverizing a mixture of a solidifying agent, a ferromagnetic powder, and metal particles so that at least a part of the metal particles is nano-sized. The metal particles may all be nano-sized. Here, the nano size means a particle size of several nm to submicron.

  The nano-dispersion is a dispersion in which metal particles including nano-sized metal particles are dispersed in a solidifying agent, and the surface of the nano-sized metal particles is coated with the solidifying agent. In general, when a metal is refined to a nano size, it is oxidized and deactivated in the environment. However, in this nano dispersion, a solidifying agent that covers the surface of the nano size metal particles is mostly composed of oxygen particles. Since it prevents direct contact with carbon dioxide or water, nano-sized metal particles can maintain high activity even in the atmosphere. Such a nanodispersion or a mixture of the nanodispersion and a solidification aid can be suitably used as an insolubilizing / concentrating / separating agent for grinding soil.

  Although the addition amount of the nano-dispersion with respect to grinding soil changes with radioactive substance concentration in soil, as shown in the below-mentioned Example, it can be set as about 2 to 10 weight% of radioactive substance contaminated soil. The ratio of each drug in the nanodispersion can be 2/2/5 by weight ratio of ferromagnetic powder / metal particles / solidifying agent. The amount of solidification aid added can be about 5% by weight with respect to radioactive material contaminated soil.

  The stirring and mixing device 11 is not limited to a specific device. What is necessary is just to be able to stir and mix the nanodispersion, the solidification aid and the grinding soil uniformly. Examples of the stirring and mixing device 11 include a ball mill-like horizontal cylindrical rotary mixer and a concrete mixer-like stirring and mixing device. The stirring and mixing device 11 is preferably of a type in which the grinding soil is not pulverized or crushed when the nanodispersion, the solidification aid and the grinding soil are uniformly stirred and mixed. When soil particles are crushed, small crushed particles are generated. If the crushed small particles are mixed with soil particles that are not crushed, it leads to a decrease in the weight loss rate.

  The agitation and mixing time varies depending on the agitation and mixing device 11 and the amount of radioactive material-contaminated soil that is the object to be treated, but can be set to about 0.5 to 4 hours as shown in Examples described later. The stirring and mixing operation may be performed at normal temperature and atmospheric pressure. By the above operation, the radioactive substance can be insolubilized and concentrated and separated.

  The ground soil made insolubilized and concentrated and separated is sent to the magnetic separator 13 where it is separated into high-concentration contaminated soil and low-concentration contaminated soil by magnetic separation. Of the ground soil made insolubilized and concentrated and separable, soil containing a large amount of ferromagnetic powder is adsorbed to a magnet and can be adsorbed and separated using a magnet. The magnetic separation device 13 is not limited to a specific device, and can be appropriately selected and used according to the processing amount. As the magnetic separator 13, a magnet drum separator is exemplified.

  As shown in the below-mentioned Example, when it was made to adsorb | suck using a commercially available magnet, about 50-60 weight% of soil was adsorb | sucked to the magnet. As a result of the experiment, about 80 to 90% of the radioactive material contained in the insolubilized and concentrated and separable soil was contained in the soil adsorbed by the magnet (magnetically attached soil). This is because most of the radioactive substances contained in the soil adhere to silt and clay with a large specific surface area, and the silt and clay with a small particle size adhere to drugs containing ferromagnetic powder because of the large specific surface area. It is thought that it is easy. For this reason, the magnetic separation process is also a concentration separation process for concentrating and separating radioactive substances.

  The concentration / insolubilization / separation process of radioactive material in this method is considered as follows. In the following description, the radioactive substance is cesium Cs, the ferromagnetic powder is iron Fe, the metal particles are metallic calcium Ca, the solidifying agent is calcium oxide CaO, and the solidification aid is sodium dihydrogen phosphate. FIG. 9 is a schematic diagram for explaining a mechanism (assuming) that a radioactive substance can be insolubilized / concentrated and separated by a chemical action, and FIG. 10 is included in the soil that has been insolubilized / concentrated / separated. It is a schematic diagram for demonstrating the mechanism (presumption) which physically concentrates and isolates a radioactive substance.

First, Ca ²⁺ replaces Cs ⁺ present on the surface of untreated soil (grinding soil) (Ca ²⁺ is an extremely small amount but an excessive amount compared to the amount of radioactive elements), and then Cs ⁺ is water in the secondary particles. In addition, a calcium hydroxide film insoluble in water is formed, and the entire secondary particles are solidified.

When the magnet is brought close to the solidified secondary particles, it is attracted to the magnets by the iron particles encapsulated in the secondary particles. Silt and clay having a small particle size have a large specific surface area, a large amount of iron particles, and light weight, so that they are adsorbed by a magnet. On the other hand, gravel and sand have a small specific surface area, a relatively small content of iron particles, and a heavy weight, so that they are not adsorbed by the magnet. Since most of the radioactive materials contained in the soil adhere to silt and clay with a large specific surface area, contaminated soil (=
It is possible to concentrate / separate secondary particles (concentrated and adsorbed by Cs).

  The method for treating radioactive material-contaminated soil according to the fifth embodiment of the present invention has a larger number of steps than the method for treating radioactive material-contaminated soil according to the first to fourth embodiments of the present invention. The weight loss rate can be increased. Moreover, the radioactive substance contained in soil can be insolubilized, without generating an excessive waste like the processing method of radioactive substance contaminated soil of 3rd Embodiment.

  In the insolubilization / concentration separation enabling process, the solidification aid is agitated and mixed with the nano-dispersion to insolubilize and concentrate the radioactive substance, but the solidification aid is insolubilization / concentration separation enabling process. Addition, stirring and mixing in the middle of the insolubilization / concentration separation enabling process or after the insolubilization / concentration separation enabling process and before the magnetic separation process, so that the ground soil can be insolubilized and concentrated and separated. You may let them.

  Further, at the stage of the insolubilization / concentration / separation enabling step, the solidification aid may be added to the magnetized soil, mixed, and solidified without adding the solidification aid. The reason why the solidification aid is added and solidified only in the magnetized soil is that the radioactive material is concentrated in the magnetized soil. By adding a solidification aid, elution of radioactive substances can be completely prevented. In addition, since the magnetically-attached soil has a small particle size, it can be easily handled by solidifying with a solidification aid.

  Similarly, the grinding soil (residue) that is not adsorbed by the magnet may be solidified by adding, mixing, and solidifying, but (1) the radioactivity after the insolubilization / concentration separation enabling process About 80-90% of the radioactive material contained in the material-contaminated soil is contained in the magnetized soil. (2) The residue has a relatively large particle size and is easy to handle. (3) The residue also has a surface. Since the radioactive substance is difficult to elute because it is coated with a solidifying agent, the residue may be solidified using a solidification aid, if necessary, based on the results of the dissolution test. Thereby, the usage-amount of a solidification adjuvant can be suppressed.

  As described above, as shown in the first to fifth embodiments, the radioactive material-contaminated soil treatment method of the present invention is simple in operation and can be efficiently decontaminated and reduced (reduced) without generating extra waste. Can be). In addition, since the treated soil is insolubilized and elution of radioactive substances is prevented, it is preferable as a method for treating radioactive substance-contaminated soil. Furthermore, since the method for treating radioactive material-contaminated soil of the present invention performs all operations in a dry manner, unlike the wet treatment method, wastewater and waste liquid do not need to be treated.

  Various forms can be considered for the method for treating radioactive material-contaminated soil of the present invention in addition to the above-described embodiment, and the method can be changed and used without changing the gist.

  In the method for treating radioactive material-contaminated soil shown in the third embodiment, the solidifying agent is added to and mixed with the radioactive material-contaminated soil after the classification step to insolubilize the radioactive material, but the order of the classification step and the insolubilization step is reversed. First, a solidifying agent is added to and mixed with radioactive material-contaminated soil that is to be treated to insolubilize the radioactive material, and then insolubilized radioactive material-contaminated soil having a particle size less than a predetermined particle size from among the insolubilized radioactive material-contaminated soil May be separated by dry classification to decontaminate radioactive material contaminated soil. Furthermore, the insolubilization step and the classification step may be performed in parallel.

  In the method for treating radioactive material contaminated soil shown in the fifth embodiment, a chemical is added to the ground soil after the grinding step so as to be insolubilized and concentrated, and then the radioactive material is concentrated and separated by magnetic separation. Radioactive material-contaminated soil with a two-stage grinding process in which the ground soil after the grinding process is dry-classified to obtain a ground soil with a predetermined particle size, which is then ground again and then insolubilized and concentrated and separated. It can also be set as the processing method. In this case, the subsequent grinding process can be considered in the same manner as the grinding process described so far, and the insolubilization / concentration separation enabling process after the subsequent grinding process and the magnetic separation process are also described so far. It can be considered in the same manner as the magnetic separation process.

  Further, in the radioactive material contaminated soil treatment method shown in the fifth embodiment, the grinding step is performed after the dry classification step. In the radioactive substance contaminated soil treatment method shown in the fifth embodiment, the dry classification step and the grinding step are performed. The order may be changed, and the dry radioactive material contaminated soil may be scraped off and then subjected to dry classification, followed by insolubilization / concentration separation enabling step and concentration separation step. This method can be suitably used particularly when the soil is highly contaminated with radioactive substances and the concentration of radioactive substances contained in the coarse-grained soil is high.

<Example 1>
By processing radioactive material contaminated soil in the order of (1) drying step, (2) soil grinding step, (3) dry classification step, (4) insolubilization / concentration separation enabling step, and (5) magnetic force sorting step. Carried out. Hereinafter, the procedure of Run-A is described as a representative example.

(1) Drying process About 15 kg of radioactive material contaminated soil was dried at a temperature of 105 ° C. for 45 minutes using a dryer to obtain radioactive material contaminated soil having a moisture content of 1.6% by weight. The moisture content of the radioactive material contaminated soil before drying was 15.6% by weight. Cs137 contained in the radioactive material contaminated soil after drying was 3681 Bq / kg, and Cs134 was 2521 Bq / kg.

(2) Grinding Step A concrete mixer (inclination chamber tilt 70 °) with an internal volume of 110 L was filled with 12.29 kg of dried radioactive material-contaminated soil, stirred for 2 hours, and the surface of the radioactive material-contaminated soil was scraped off. The fine powder (dust) generated at this time was sucked with a suction device, captured with a HEPA filter, and collected. The radioactive material contaminated soil whose surface was shaved was 11.83 kg, and the fine powder captured by the HEPA filter was 0.46 kg. Cs137 contained in the fine powder was 7364 Bq / kg, and Cs134 was 4991 Bq / kg. From this result, it can be seen that radioactive substances are attached and adsorbed on the soil surface.

(3) Dry classification process Using a sieve, coarse soil of 7 mm or more was separated from radioactive material-contaminated soil whose surface was scraped.

(4) Insolubilization / concentration / separation process The stirring and mixing apparatus used a horizontal cylindrical rotary mixer. A 1.5-liter cylindrical container was filled with 500 g of radioactive material-contaminated soil from which coarse soil of 7 mm or more was separated and 50 g of nanodispersion (PCA151) which is an insolubilized / concentrated separable agent. The cylindrical container was sealed, set on a turntable, and stirred at 200 rpm for 1 hour. A horizontal cylindrical rotary mixer is a rolling ball mill-like device, but unlike a ball mill, it is not filled with balls.

A nano-dispersion (PCA151), which is an insolubilized / concentrated separable drug, was prepared as follows. Iron powder (Kishida Chemical Co., Ltd.) having a particle size of 0.15 mm as the ferromagnetic powder, and metal having a purity of 99%, a particle size of 2 to 2.5 mm, and a surface area of 0.43 to 0.48 m ² / g as the metal particles. Calcium (Kishida Chemical Co., Ltd.) was used. Calcium oxide CaO, metallic calcium Ca, and iron powder Fe calcined at 825 ° C. for 2 hours were made to have a weight ratio of Fe / Ca / CaO = 2/2/5, and this was 60% at 600 rpm in an argon gas atmosphere in a planetary ball mill. A normal temperature pulverization treatment was performed for a minute. The particle size distribution of the obtained nanodispersion (PCA151) is shown in FIG. The particle size of the nano-dispersion was measured using a nano-particle analyzer NANO SIGN LM-20 (measuring Brownian motion and measuring particle size). The particle size was generally in the range of 20 to 500 nm, many were about 60 to 300 nm, and most were about 120 to 210 nm.

(5) Magnetic force selection process The ground soil subjected to the insolubilization / concentration / separation process was subjected to magnetic force selection using a lattice type magnetic separation device. The soil adsorbed on the magnet (magnetically adsorbed soil) was 284.28 g, the soil not adsorbed on the magnet (residue) was 240.95 g, and the weight ratio of the magnetically adsorbed soil was about 54.1%. Cs137 contained in the magnetized soil was 3195 Bq / kg, and Cs134 was 2224 Bq / kg. On the other hand, Cs137 contained in the residue was 845 Bq / kg, and Cs134 was 592 Bq / kg. The Cs concentration in the magnetized soil is about 3.8 times the Cs concentration in the residue, and it can be seen that radioactive substances can be concentrated and separated by magnetic separation.

  The same experiment was conducted by changing the conditions of the insolubilization / concentration separation enabling treatment. In Run-E, an AL-containing nanodispersion was used. Table 2 shows the insolubilization / concentration / separation processing conditions, decontamination rate, and weight loss rate. Table 3 shows the weight ratio in each operation of Run-B and the ratio of Cs137 and Cs134 contained in the soil as representative examples. Here, the decontamination rate and the weight loss rate were calculated by the equations (1) and (2), respectively.

  As a result of the experiment, the decontamination rate was 77.4-88.1%, the weight loss rate was 50.6-61.4%, and the maximum decontamination rate was 88.1%. The weight loss rate was 50.6%. The higher the decontamination rate, the smaller the weight loss rate. Regarding the relationship between the stirring and mixing time and the decontamination rate in the insolubilization / concentration separation enabling treatment, the longer the stirring and mixing time, the higher the decontamination rate. In addition, when the amount of the insolubilized / concentrated / separable agent was decreased, the decontamination rate decreased and the weight loss rate tended to increase.

<Example 2>
Treatment of radioactive material contaminated soil: (1) drying step, (2) dry classification step, (3) grinding step, (4) insolubilization / concentration separation enabling step, (5) magnetic force sorting step, (6) residue insolubilization -It carried out by performing in order of concentration separation possible process and (7) magnetic force selection process. Example 2 is characterized in that the ground soil that has been insolubilized / concentrated / separated is magnetically selected, and the resulting residue is again insolubilized / concentrated / separated, and this is magnetically selected. The procedure of each process is basically the same as that of the first embodiment.

  Table 4 shows the treatment conditions, decontamination rate, and weight loss rate that enable insolubilization and concentration separation. The decontamination rate was 82.9%, and the weight loss rate was 53.5%. Considering that the stirring and mixing time of the insolubilization / concentration separation enabling process in Example 2 is 2 hours, both the decontamination rate and the weight reduction rate are the same as in Example 1, and the insolubilization / concentration separation enabling process and magnetic separation are performed. The effect of performing 2 times was not seen.

<Example 3>
The radioactive material contaminated soil is treated by (1) drying process, (2) dry classification process, (3) grinding process, (4) insolubilization / concentration separation enabling process, and (5) magnetic separation process. did. In Example 1 and Example 3, the order of the dry classification process and the grinding process is reversed, but the procedure for each process is basically the same as in Example 1.

  Table 5 shows the experimental conditions, the decontamination rate, and the weight loss rate. Run-J used dry radioactive material contaminated soil from which coarse soil of 3 mm or more was separated using a sieve in dry classification, and the coarse soil of 3 mm or more was removed in the grinding process. Further, in the insolubilization / concentration separation enabling process, about 13 kg of ground soil was insolubilized / concentrated / separated using the same concrete mixer as in the grinding process.

  In Run-J, the decontamination rate was as small as 60.9%, and conversely the weight loss rate was as high as 72.1%. On the other hand, in Run-K using the same stirring and mixing apparatus as in Example 1 for the insolubilization / concentration separation enabling process, the values were almost the same as the decontamination rate and the reduction rate in Example 1. From this result, it can be said that the order of the dry classification process and the grinding process does not greatly affect the decontamination rate and the weight reduction rate.

<Example 4>
Treatment of radioactive material contaminated soil: (1) Drying process, (2) Dry classification process, (3) Grinding process, (4) Grinding soil dry classification process, (5) Grinding soil grinding process, (6) Insolubilization / concentration It was carried out by performing the separation enabling step and (7) the magnetic force selection step in this order. Compared with Run-K of Example 3, (4) grinding soil dry classification step and (5) grinding soil grinding step are added. In the ground soil dry classification process of (4), using a sieve, the ground soil of 3 mm or more is separated from the radioactive material-contaminated soil whose surface has been scraped off, and in the grinding soil grinding process of (5), the ground soil grinding process is less than 3 mm. The surface of the grinding soil was shaved off. Other conditions are the same as those of Run-K.

  As a result of the experiment, the decontamination rate was 75.3%, and the weight loss rate was 62.5%. From this result, the effect of performing the grinding process in two stages was not seen.

DESCRIPTION OF SYMBOLS 1 Processing apparatus 3 Dryer 5 Vibrating sieve 7 Grinding apparatus 9 Stirring mixing apparatus 11 Stirring mixing apparatus 13 Magnetic sorting apparatus

Claims (10)

Radioactive contaminants that are to be treated are determined by dry classification, and low-concentration contaminants that have a radioactive concentration lower than a predetermined size that is lower than the concentration to be treated and a high concentration of radioactive material that is greater than the amount to be treated. In the method for treating radioactive material contaminants, which are separated into high-concentration contaminants less than the size, and decontaminating the radioactive material contaminants to be treated by removing the high-concentration contaminants,
Prior to the dry classification, an adsorbent capable of suppressing the aggregation and solidification of radioactive material contaminants and preferentially adsorbing small radioactive material contaminants is added to and mixed with the radioactive material contaminants to be treated. A small radioactive substance contaminant is adsorbed on an adsorbent, and the adsorbent adsorbing the radioactive substance contaminant of less than a predetermined size and the radioactive substance contaminant is separated as the high-concentration contaminant in the dry classification. processing method to that radioactive materials contaminants. The method for treating radioactive material contaminants according to claim 1 , wherein the adsorbent is a combustible adsorbent. The radioactive material contaminant treatment according to claim 1 or 2 , further comprising an incineration step of incinerating the high-concentration contaminants separated by the dry classification to obtain incineration ash of the high-concentration contaminants. Method. Further adding a solidifying agent to the said high density contaminants separated by dry classification and / or the low density contaminants, mixed in claim 1 or 2, characterized in that it comprises an insolubilization step of insolubilizing the radioactive material The radioactive material contamination treatment method of description. The method for treating radioactive material contaminants according to claim 3 , further comprising an insolubilization step of adding and mixing a solidifying agent to the incinerated ash of the high-concentration contaminants to insolubilize the radioactive material. The method for treating radioactive material contaminants according to claim 4 or 5 , further comprising adding and mixing a solidification aid together with the solidifying agent to insolubilize the radioactive material. The method for treating radioactive material contaminants according to claim 4, wherein the solidifying agent is calcium oxide. The method for treating radioactive material contaminants according to claim 6 , wherein the solidification aid is a phosphate. The radioactive material pollutant is radioactive material-contaminated soil, radioactive material-contaminated industrial waste, a mixture of radioactive material-contaminated soil and radioactive material-contaminated industrial waste, and a mixture of these and incinerated ash containing the radioactive material. The method for treating radioactive material contaminants according to any one of claims 1 to 8 , wherein: The radioactive material-contaminated industrial waste according to claim 9 , wherein the radioactive material-contaminated industrial waste contains at least one of rubble, waste plastic, wood waste, paper waste, and crushed materials thereof. Method.