JP6047814B2 - Radioactive material contaminated soil treatment method and radioactive material contaminated soil treatment system - Google Patents

Description

The present invention relates to a radioactive substance- contaminated soil treatment method and a radioactive substance- contaminated soil treatment system.

  Conventionally, contaminated soil treatment for collecting contaminated soil and removing contaminants has been performed, and representative methods include wet decontamination methods and dry decontamination methods (see, for example, Patent Documents 1 and 2). ). In the wet decontamination method, the contaminated soil is washed with, for example, high-pressure washing water to isolate the contaminants together with the washing water, and the washed soil is returned to the collection site. In the dry decontamination method, soil with a small particle size containing a large part of harmful substances is separated and collected, and the soil with a large particle size is returned to the collection site. Furthermore, a decontamination method combining wet and dry methods has also been proposed (see, for example, Patent Document 3).

JP 2004-249241 A JP 2001-219155 A JP 2007-050347 A

However, each of the conventional wet decontamination method and dry decontamination method has the following problems. First, in the wet decontamination method, a large amount of contaminated water is generated, and a large amount of turbid water treatment is required after washing. In addition, when installing a muddy water treatment plant, construction of a large-scale foundation is indispensable. In addition, the wet decontamination method is not suitable for decontamination of farmland soil, because even high-quality components such as minerals contained in the soil are washed away.
On the other hand, the dry decontamination method uses the property that pollutants are likely to adhere to fine particles in the soil, classifies the soil according to particle size, and collects only fine-grained soil. However, the classification accuracy may vary depending on the state of the soil to be treated, such as the moisture content and soil aggregation.

Furthermore, the decontamination method that combines wet and dry methods includes a step of washing after classification, and in addition to the same problems as wet methods, including a step of polishing to soil of a non-contaminated particle size, Efficient decontamination is difficult.
The present invention has been made in view of the above-mentioned problems, and the object of the present invention is a contaminated soil treatment technique that can efficiently perform decontamination without generating sewage during the treatment of contaminated soil. Is to provide.

(Aspect of the Invention)
The following aspects of the present invention exemplify the configuration of the present invention, and will be described separately for easy understanding of various configurations of the present invention. Each section does not limit the technical scope of the present invention, and some of the components of each section are replaced, deleted, or further while referring to the best mode for carrying out the invention. Those to which the above components are added can also be included in the technical scope of the present invention.

(1) Contaminated soil collection process for collecting soil contaminated with radioactive substances ;
A drying step of drying the soil collected in the contaminated soil collection step;
A crushing step of breaking up agglomeration of the soil dried in the drying step;
A classification step of separating the soil crushed in the pulverization step according to the particle size;
Among the soils classified in the classification step, an isolation step for isolating fine-grained soil ,
A radioactivity level measurement step for measuring the radiation dose of the remaining soil that is not isolated from the soil classified in the classification step,
In the radioactivity level measurement step, the remaining soil whose dose is less than or equal to a predetermined value is reused, and in the radioactivity level measurement step, if the dose exceeds a predetermined value, the process returns to the classification step, and the classification step A radioactive substance- contaminated soil treatment method that repeats the isolation step and the radioactivity level measurement step (Claim 1).
Radioactive contaminated soil processing method according to this aspect, a soil contaminated by radioactive material collected in the contaminated soil collected process is dried in the drying step, further, the aggregation of the dried soil in crushing step By loosening, the particle size of the dried soil is adjusted so as to be in a state suitable for soil classification according to the particle size in the subsequent classification step. And, when the soil crushed in the pulverization step is classified in the classification step according to the particle size, the water content of the collected soil, the soil aggregation, etc., to the state of the soil to be treated The occurrence of variations in classification accuracy due to this will be avoided and classification accuracy will be improved. And among the soil classified in the classification process, the fine-grained soil is isolated in the subsequent isolation process, and the remaining soil is returned to the soil collection site, so that the particle size including most of the harmful substances is reduced. Small soil is separated and collected, and soil with a large particle size is returned to the collection site.
In addition, when decontaminating soil contaminated with radioactive substances, the radiation dose of the remaining soil that has not been isolated out of the soil classified in the classification process is measured, and if the dose exceeds the specified value, proceed to the classification process. This ensures the isolation and storage of soil containing harmful substances.
And since soil washing | cleaning by the dry-type decontamination method is made | formed by the above each process, by-products, such as contaminated water, do not generate | occur | produce over the whole process. In addition, since necessary components (nutrients, etc.) of the soil are not washed away, the soil after washing is returned to the soil collection site and can be easily reused. Further, by crushing and classifying the dried soil, it is not necessary to perform a process that requires a processing time such as pulverizing a large amount of soil, and the processing efficiency is increased.

(2) In the above item (1), among the soils classified in the classification step, a finely pulverizing step for further finely pulverizing the particle size of the finely divided soil;
A secondary classification step of classifying the soil pulverized in the fine pulverization step according to the particle size;
Of the soil classified in the secondary classification step, a secondary isolation step of isolating fine-grained soil ;
A secondary radioactivity level measurement step for measuring the radiation dose of the remaining soil not isolated from the soil classified in the secondary classification step, and
In the secondary radioactivity level measurement step, the remaining soil whose dose is less than a predetermined value is reused, and when the secondary radioactivity level measurement step exceeds the predetermined value, the secondary classification step is performed. The radioactive substance- contaminated soil treatment method in which the secondary classification step, the secondary isolation step, and the secondary radioactivity level measurement step are repeated (claim 2).
In the contaminated soil treatment method described in this section, among the soils classified in the classification step, the finely pulverized soil particle size is further finely pulverized in the fine pulverization step, and the pulverized soil in the fine pulverization step is In the subsequent secondary classification step, further classification is performed according to the particle size. And among the soil classified in the secondary classification process, the fine-grained soil is isolated in the subsequent secondary isolation process, and the remaining soil is returned to the soil collection site, so that most of the harmful substances are removed. Soil that can be reused because it contains more small fractions of soil that are collected, isolated, isolated, and reduced in volume, returning as much soil as possible to the collection site. Yield improvement can be expected. In addition, when decontaminating soil contaminated with radioactive substances, the radiation dose of the remaining soil that has not been isolated out of the soil classified in the secondary classification process is measured. By returning to the next classification process, the soil containing harmful substances is isolated and stored. Also in the invention of this section, the soil is washed by the dry decontamination method throughout the entire process, and no by-products such as contaminated water are generated.

(3) In the above (2), in the fine pulverization step, the surface portion of the soil particles is exfoliated to polish the soil, and the surface portion of the exfoliated soil particles is classified as fine particles in the secondary classification step A method for treating contaminated soil (claim 3).
In the method for treating contaminated soil described in this section, in the fine pulverization step, the surface portion of the soil particles is exfoliated to polish the soil, and the surface portion of the soil particles exfoliated in the secondary classification step is classified as fine particles. By doing so, the predetermined action of the above item (2) is more effectively achieved. In other words, since the soil fine particles have a lot of contaminants attached to the surface portion, the soil is gradually pulverized from the surface in such a way that it is ground instead of being pulverized with strong force. If the pulverized and peeled surface portion is separated and separated as fine particles by a secondary classification process, the fine particles to which the contaminants are attached can be separated and isolated very efficiently.

(4) In the above items (1) to (3), the radioactive substance-contaminated soil treatment method for drying the soil to a predetermined dryness by supplying heated air in the drying step (claim 4).
The contaminated soil treatment method described in this section is one in which the soil is washed by the dry decontamination method throughout the entire process by drying the soil to a predetermined dryness by supplying heated air in the drying process. By-products such as contaminated water are not generated.

(5) a stirring and drying device for drying the collected soil contaminated with radioactive substances and performing a drying process ;
An impact crushing device for crushing the soil dried by the stirring and drying device, and performing a crushing step ;
An airflow classifier that performs a classification process to classify the soil crushed by the impact crusher according to the particle size ;
A radiation measuring instrument that performs a radioactivity level measurement step that measures the radiation dose of the remaining soil that is not isolated after the isolation step that isolates fine-grained soil among the soil separated by the airflow type ball separator viewing including the door,
The remaining soil detected in the radioactivity level measurement step using the radiation measuring instrument is reused for the residual soil whose dose is less than a predetermined value, and the soil whose dose exceeds the predetermined value is returned to the airflow type ball separator. A radioactive substance- contaminated soil treatment system that repeats the dividing step, the isolation step, and the radioactivity level measurement step (Claim 5).
The radioactive material- contaminated soil treatment system described in this section collects soil contaminated with radioactive material , puts it in an agitation dryer and dries it (drying process), and further agglomerates the dried soil with an impact crusher It is a thing to loosen in (disintegration process). And it adjusts so that it may be in the state suitable for the classification of the soil according to a particle size with the airflow classifier by the soil which dried and the aggregation was released (classification process). As a result, when the soil crushed by the impact type crushing device is classified according to the particle size by the airflow type classifying device, the moisture content of the collected soil, the soil to be treated, such as agglomeration of the soil This avoids the variation in classification accuracy due to the state of the above, and improves the classification accuracy. And among the soil classified by the airflow classifier, the fine-grained soil, that is, the small-sized soil containing most of the harmful substances is isolated in the subsequent isolation step, and the remaining, by returning a significant soil sampling locations, and performs soil cleaning with dry decontamination method.
In addition, the remaining soil detected in the radioactivity level measurement process using the radiation measuring instrument is reused, and the soil whose dose exceeds the specified value is returned to the airflow type ball separator. By repeating the ball-spinning process, the isolation process, and the radioactivity level measurement process, it is possible to ensure the isolation and storage of soil containing harmful substances.
Therefore, by-products such as contaminated water are not generated throughout the entire process performed by the present system. In addition, since necessary components (nutrients, etc.) of the soil are not washed away, the soil after washing is maintained in a state suitable for returning to the soil collection site for reuse. Further, by crushing and classifying the dried soil, it is not necessary to perform a process that requires a processing time such as pulverizing a large amount of soil, and the processing efficiency is increased.

(6) In the above item (5), among the soils classified by the airflow classifier , a centrifugal fluidized pulverizer for performing a fine pulverization step for further finely pulverizing the particle size of finely sized soil ;
An air-flow classifier for performing a secondary classification step of classifying soil finely pulverized by the centrifugal fluid pulverizer according to the particle size;
A secondary radioactivity level measurement step of measuring the radiation dose of the remaining soil that is not isolated after the secondary isolation step of isolating the fine-grained soil among the soil separated by the airflow type ball separator only contains a radiation measuring instrument to perform,
The residual soil detected in the secondary radioactivity level measurement step using the radiation measuring instrument is reused and the secondary classification step is performed on the soil whose dose exceeds the predetermined value. A radioactive material- contaminated soil treatment system that returns to the airflow type ball separator and repeats the secondary classification step, the secondary isolation step, and the secondary radioactivity level measurement step (Claim 6).
The radioactive material- contaminated soil treatment system described in this section is a method of further finely pulverizing the finely sized soil of the soil classified by the airflow classifier (classifying step) with a centrifugal fluid pulverizer (fine pulverization). Step), the pulverized soil is again further classified according to the particle size by the airflow classifier (secondary classification step). Then, by separating the finely divided soil from the secondary classified soil and returning the remaining soil to the soil collection site, the small particle size soil containing most of the harmful substances can be classified more precisely. Separately, the volume of soil collected, isolated and stored is reduced, and as much soil as possible is returned to the collection site (secondary isolation process). Also in the invention of this section, soil washing is performed by the dry decontamination method throughout the entire process carried out by this system, and no by-products such as contaminated water are generated. Moreover, among the soils classified in the secondary classification process, the fine-grained soil is isolated in the subsequent secondary isolation process, and the remaining soil is returned to the soil collection site, so that most of the harmful substances are removed. Since the soil with small particle size is collected more precisely, it can be isolated and stored, so the volume of the soil to be isolated and stored can be reduced, and as much soil as possible can be returned to the collection site. It can be expected to improve the yield of soil . Moreover, the residual soil detected in the secondary activity level measurement process using the radiation measuring instrument is reused, and the secondary classification process is performed on the soil whose dose exceeds the predetermined value. It returns to the airflow type ball separator and repeats the secondary classification process, secondary isolation process, and secondary radioactivity level measurement process to ensure the isolation and storage of soil containing harmful substances. .

(7) A radioactive substance- contaminated soil treatment system according to (5) and (6) above, wherein each of the devices is configured to be movable (claim 7).
The radioactive substance- contaminated soil treatment system described in this section is configured so that each apparatus described in (5) and (6) above can be moved, so that each apparatus can be operated at a soil collection site to perform dry decontamination. The method involves collecting, drying, crushing, and classifying the soil by the method, separating and collecting the small-sized soil containing most of the harmful substances, and returning the remaining soil to the collection site. In addition, for example, each device is mounted on a trailer bed or a special vehicle on which each device is mounted is configured so that each device described in the above items (5) and (6) can be moved. These trailers and special vehicles are mounted separately according to the size of each device, or a plurality of types (or all) are mounted on one vehicle, and at the soil collection site, It is arranged so that a predetermined work process is carried out smoothly. Moreover, when this system is installed at a soil collection site, no foundation work or the like is required, the construction period required for installation is short, and it is easy to move to a different soil collection site and operate.

  Since this invention was comprised in this way, in the process of a contaminated soil, sewage does not generate | occur | produce and it becomes possible to perform decontamination efficiently.

(A) is a flowchart which shows the contaminated soil processing method which concerns on embodiment of this invention, (b) is a schematic structure of the contaminated soil processing system which concerns on the contaminated soil processing method of (a) and FIG. FIG. It is a flowchart which shows the application example of the contaminated soil processing method shown by FIG. It is a schematic diagram which shows the stirring drying apparatus used for the contaminated soil processing method which concerns on embodiment of this invention, (a) is longitudinal direction sectional drawing, (b) is AA sectional drawing of (a). . It is a schematic cross section which shows the impact-type crushing apparatus used for the contaminated soil processing method which concerns on embodiment of this invention. It is a schematic cross section which shows the airflow classifier used for the contaminated soil processing method which concerns on embodiment of this invention. It is a schematic cross section which shows the centrifugal fluid crushing apparatus used for the contaminated soil processing method which concerns on embodiment of this invention. The image at the time of comprising the contaminated soil processing system which concerns on embodiment of this invention so that a movement is shown is shown, (a), (b) is an image figure of the special vehicle carrying each apparatus which comprises this system It is.

DESCRIPTION OF EMBODIMENTS Hereinafter, embodiments for carrying out the present invention will be described with reference to the accompanying drawings. Here, parts that are the same as or equivalent to those of the prior art are assigned the same reference numerals, and detailed descriptions thereof are omitted.
The contaminated soil treatment method according to the embodiment of the present invention includes the steps shown in FIG. 1 (a), and will be described below in order. Moreover, this method is implemented by the contaminated soil processing system 1 shown by FIG.1 (b). Incidentally, contaminated soil, for example, directed to a contaminated soil by radioactive substances such as cesium 137.

S100 (contaminated soil collection step): Collects contaminated soil. Depending on the soil, using an appropriate civil engineering machine such as a backhoe, or if necessary, from the ground surface to an appropriate depth. It is a process of collecting soil.
S110 (drying step): This is a step of drying the soil collected in the contaminated soil collecting step (S100) using the stirring and drying device 2 (see FIGS. 1B and 3).
S120 (crushing step): a step of loosening the agglomeration of the soil dried in the drying step (S110) using the impact crushing device 4 (see FIG. 1B and FIG. 4).
S130 (classification step): a step of classifying the soil crushed in the pulverization step (S120) according to the particle size using the airflow classifier 6 (see FIG. 1B and FIG. 5). .
S140 (management process): This is a process of isolating fine-grained soil from the soil classified in the classification process (S130) and returning the remaining soil to the soil collection site, and includes the following steps.

S150 (isolation step): Fine particles classified in the classification step (S130) have a high radioactivity level (radiation dose) due to the property that contaminants are likely to adhere to fine particles in the soil. Therefore, fine particles should be isolated and stored by an appropriate method. In addition, since the particle size of the fine particle classified here changes with kinds of soil, it is preferable to investigate the particle size of the fine particle with a high radioactivity level beforehand, and to determine the range.
S160 (radioactivity level measurement step): Because of the property that pollutants easily adhere to fine particles in the soil, the coarse particles classified in the classification step (S130) have a low radioactivity level (radiation dose). However, as a precaution, the radioactivity level of coarse particles is also measured using a radiation measuring instrument. And when the radioactivity level of elementary particles is higher than a reference value appropriately determined in advance, the coarse particles are returned to the classification step (S130).
S170: In the radioactivity level measurement step (S160), when the radioactivity level of the elementary particles is lower than a predetermined reference value, the coarse particles are returned to the soil collection site.

Further, FIG. 2 shows each step of S100 to S140, S160, and S170 in the flow of FIG. 2 in which an application example of the contaminated soil treatment method according to the embodiment of the present invention is shown. Since the content is the same as or corresponding to the corresponding process shown in FIG.
S220 (fine pulverization step): Among the soils classified in the classification step (S130), the fine particle size of the soil (fine particles) is determined by the centrifugal fluidized pulverizer 8 (see FIGS. 1B and 6). It is a process of using and crushing further finely.
In the above-described fine pulverization step, it is preferable that the soil is gradually pulverized from the surface in such a manner that the soil is not pulverized all at once with a strong force. This is because the fine particles of the soil put into the centrifugal flow device 8 have a lot of contaminants attached to the surface portion. If the peeled surface portion is separated and separated as fine particles by a secondary classification step, the fine particles to which the contaminants are attached can be separated and isolated very efficiently.
S230 (secondary classification step): Using the airflow classifier 6 (see FIGS. 1B and 5) similar to the classification step (S130), the soil finely crushed in the fine pulverization step (S220) This is a step of sorting according to the particle size.
S240 (secondary management step): a step of isolating fine-grained soil among the soils classified in the secondary classification step (S230) and returning the remaining soil to the soil collection site. Is included.

S250 ( secondary isolation step): Fine particles classified more precisely in the secondary classification step (S230) have a higher radioactivity level (radiation dose). Therefore, fine particles should be isolated and stored by an appropriate method.
S260 (Radioactivity level measurement step): The coarse particles classified in the secondary classification step (S230) have a low radioactivity level (radiation dose). However, as a precaution, the radioactivity level of coarse particles is also measured using a radiation measuring instrument. Then, when the radioactivity level of the coarse particles is higher than a predetermined reference value, the coarse particles are returned to the secondary classification step (S230).
S270: In the radioactivity level measurement step (S260), when the radioactivity level of the coarse particles is lower than a predetermined reference value, the coarse particles are returned to the soil collection site.

Subsequently, a specific configuration of each apparatus used in the above steps will be described below. Each of the following devices is an example of a device suitable for the present embodiment, and the contaminated soil treatment system 1 can be configured by appropriately replacing each device with the same function. Is.
As illustrated in FIG. 3, the stirring / drying apparatus 2 includes a gas dispersion plate 102 at a substantially central portion in the height direction, and includes a stirring chamber 103 in the upper portion and a blower chamber 104 in the lower portion. . The bottom plate 130 of the stirring chamber 103 is formed in a semi-circular shape with a partial semicircular cross section, and the gas dispersion plate 102 is disposed on the central arc portion.
In addition , a refractory 143 is lined on the inner wall surface of the air blowing chamber 104 including the back surface of the bottom plate 130 to protect against high-temperature hot air. The refractory 143 is also applied to the gas dispersion plate 102, and a part of the slit 120 or the slit 121 that is an opening as the gas hole is formed of the refractory 143. In this embodiment, the refractory 143 is used for the lining, but it is needless to say that the refractory may not be used depending on the temperature of the gas used.

In the stirring chamber 103, a paddle shaft 105 is rotatably supported by bearings 150 attached to both outer walls of the stirring chamber 103 via brackets. In this embodiment, six paddles 151 for stirring are attached at substantially equal intervals. Each of the paddles 151 has, for example, an arm 151a that penetrates the paddle shaft 105, and a nut 151b is screwed into the screw portion of the arm 151a with a nut 151b and tightened to tighten the paddle shaft 105. On the other hand, it is detachably attached. The paddle 151 is formed in a flat plate shape so as to scrape up the soil as the material to be dried by the rotation, and its tip is bent in the rotational direction of the paddle 151 so as to make the soil scraping more reliable. Is formed. Further, the tip of the paddle 151 is set at a position as close to the bottom plate 130. Further, the paddles 151 are attached such that the mounting angles of the paddles 151 adjacent to each other in the direction of the paddle shaft 105 are different from each other. In this embodiment, the paddles 151 adjacent to each other in the axial direction are attached so that the mounting angles in the circumferential direction are sequentially shifted by 120 degrees.

Further , in the present embodiment, a supply port 131 is provided in the upper part of the stirring chamber 103 on one end side of the paddle shaft 105, and further, the dried soil is formed on the side wall of the stirring chamber 103 on the other end side of the paddle shaft 105. An outlet 132 is provided. A lower end portion 132b of a mounting opening 132a of the outlet 132 on the side wall of the stirring chamber 103 is formed to substantially coincide with the starting end portion of the partial semicircular bottom plate 130. Further, a gas introduction port 141 is provided on the side wall of the air blowing chamber 104 located below the soil supply port 131, and the dried hot air is exhausted on the upper wall on the side where the outlet 132 of the stirring chamber 3 is located. An outlet 142 is provided.
In the present embodiment, the four paddles 151 on the supply port 131 side are attached to be inclined with respect to the axis of the paddle shaft 105, and the two facing the side wall of the outlet 132 are the axis of the paddle shaft 105. Installed in parallel. Further, the paddle 151 is attached to be inclined with respect to the axis of the paddle shaft 105, and is set to about 10 degrees in the present embodiment. The paddle 151 has an effect of moving the soil, which is a material to be dried, in the paddle axis direction due to this inclination.

  Here, in the present embodiment, the flow rate adjusting plate 125 is arranged between the space portion of the air blowing chamber 104 located below the outlet 132 and the space portion on the side where the gas inlet 141 of the air blowing chamber 104 is arranged. doing. The flow rate adjusting plate 125 is a flat plate-like member that has an upper end fixed to the gas dispersion plate 102 and is arranged so as to partition the air blowing chamber 104 into two. And the lower part is the aspect which is provided with a clearance gap without reaching the lower part of the ventilation chamber 104, and leaves | separates partially, leaving a communication part. Therefore, between the air inlet 141 side of the blower chamber 104 and the lower side of the outlet 132 of the blower chamber 104, gas flows through a gap between the flow rate adjusting plate 125 and the bottom of the blower chamber 104. It has become.

Gas distribution plate 102, the portion in the first zone indicated by reference numeral X in a direction along its arcuate openings of slits which are elongated formed as a gas hole (referred to as slit 120) is also The portion of the gas dispersion plate 102 in the second zone indicated by the symbol Y in the drawing is formed by juxtaposing slit-like openings (referred to as slits 121) formed as gas holes. In this embodiment, the length and width of the slit-shaped openings provided in the first zone X and the second zone Y are the same, but the number of slits 121 provided in the second zone Y is Compared with the slits 120 provided in one zone X, the number of units per unit area was doubled. Therefore, the opening area per unit area of the gas dispersion plate 102 in the second zone Y is approximately twice the opening area per unit area of the gas dispersion plate 102 in the first zone X.

  The procedure for operating the stirring and drying apparatus 2 having the above-described configuration to dry the collected soil is as follows. First, the collected soil is supplied into the stirring chamber 103 from the supply port 131 of the stirring / drying apparatus 2 and placed on the first zone X of the gas dispersion plate 102 and heated from the lower gas inlet 141 (hot air and hot air). Is also supplied into the blower chamber 104. Hot air supplied from the air inlet 141 into the blower chamber 104 flows into the stirring chamber 103 through the gas dispersion plate 102. Here, when a drive current machine (not shown) is driven to rotate the paddle shaft 105 and the paddle 151 is rotated, the collected soil in the first zone X is ejected from the slit 120 of the gas dispersion plate 102 at a high speed. It is fluidized by hot hot air and dried while being moved to the outlet 132 side. The agglomerated soil is beaten by the flat paddle 151 attached to the rotating paddle shaft 105 and moved toward the take-out port 132 in the paddle shaft direction while loosening the lump, and loosened little by little during this time. Dried.

Here, in order for the hot air to reach the second zone Y from the first zone X of the air blowing chamber 104, it is necessary to pass through a gap that is a communicating portion formed below the flow rate adjusting plate 125. Therefore, the amount of hot air that inevitably flows into the second zone Y of the blower chamber 104 is reduced. Therefore, the flow velocity of the hot air blown out from the slit 121 in the second zone decreases as the flow rate of the hot air decreases. In other words, the amount of hot air flowing into the second zone Y is adjusted by the size of the gap. As an example, the flow rate adjusting plate 125 adjusts the size of the flow rate adjusting plate 125 so that the size of the gap is about 10% of the original flow path area. It should be noted that the size of the gap is not limited to the size of the gap used in the present embodiment. In each actual operation, the size of the gap is determined by looking at the degree to which the collected soil is loosened. You can adjust the size. If necessary, the number of slits 121 formed in the second zone Y per unit area is larger than the number of slits 120 formed in the first zone X per unit area. The flow rate may be further reduced.

In the embodiment of the present invention, fluidization is suppressed by reducing the flow rate and flow velocity of the hot air blown up on the second zone Y of the stirring chamber 103 by the above-described configuration, and the collected soil is strongly paddle 151. Stir in. Therefore, even if there is agglomerated soil that has not been sufficiently loosened in the first zone X, the paddle 151 located on the second zone Y is gently swung away and gradually moves in the axial direction. Can be crushed or crushed. Then, the collected soil which has been crushed and dried in the stirring chamber 103 and reaches the outlet 132 side is finally scraped up to the upper opening 132a by the paddle 151 and discharged from the opening 132a through the outlet 132. The Note that the hot air obtained by drying the collected soil is discharged from the discharge port 142.
Here, the dryness of the collected soil can be controlled by adjusting the inclination angle of the paddle 151 viewed in the axial direction, the number of rotations, the temperature of hot air, and the like. Further, adjustment is possible by adjusting the opening area formed in the gas dispersion plate 102 in the second zone Y, the area of the communication portion left by the flow rate adjustment plate 125, and the like. Therefore, in the present embodiment, the collected soil can be sufficiently agitated and crushed (preliminarily crushed) by the stirring and drying device 2 as well as making the collected soil a predetermined dryness. .

As illustrated in FIG. 4, the impact crushing device 4 includes a casing 401, a rotor 402, adjustment plates 403 and 404 disposed in the casing 401, and a chain curtain 405. The casing 401 has a supply port 401a for feeding the collected soil dried by the stirring and drying device 2 on the upper side, and the chain curtain 405 is provided so as to gently close the supply port 401a. In addition, below the casing 401, a discharge port 401b for discharging the collected soil crushed by the present apparatus is opened. The rotor 402 rotates at a high speed, and a plurality of striking plates 402a are provided in the circumferential direction thereof. The adjustment plates 403 and 404 are attached to the casing 401 so that the distance to the rotor 402 can be adjusted.
Then, the collected soil thrown into the supply port 401a falls so as to push up the chain curtain 405, collides with the striking plate 402a of the rotating rotor 402, and receives a powerful blow in the tangential direction of the striking plate 402a. And thrown. Then, it collides with the adjusting plates 403 and 404 adjusted to an appropriate distance and is crushed, and at the same time, it rebounds again and collides with the collected soil that is sequentially added in the air, and further crushing proceeds. The soil crushed continuously in this manner falls within the casing 401 and is finally discharged from the discharge port 401b.

The airflow classifier 6 sorts the collected soil crushed by the impact crusher 4 (FIG. 4) into powder of a required particle size by airflow. The classification principle includes gravity classification and inertial force. It is divided roughly into classification and centrifugal classification. Centrifugal force classification suitable for mass classification of powders includes a free vortex type that swirls the air flow by making the shape of the classification chamber spiral, and the air flow is forced by rotating blades provided in the classification chamber There is a forced vortex to be swirled and a combination of these two, a free vortex and a forced vortex.
An example illustrated in FIG. 5 is configured in a cylindrical classification chamber 601 and a dispersion chamber 602 with a reduced diameter, and a vertical drive shaft 607 rotatably supported at the center of the classification chamber 601. And a rotating impeller 608A having a number of classification blades 608 that rotate integrally therewith, and a fine powder discharge port 609 communicating with the inside of the rotating blade 608A is disposed above the impeller 608A. On the outer periphery of the rotary impeller 608A, fixed wings 606 having a large number of slit-shaped openings for turning the classification air are fixed concentrically at appropriate intervals and connected to the fixed wings 606. A guide cone 610 having a reduced diameter is provided.

  Inside the dispersion chamber 602, a dispersion plate 604 is provided on a drive shaft 607 in the lower part of the rotary impeller 608A, and the collected soil crushed by the impact crusher 4 supplied from the supply port 603 is classified into the classification chamber 601. It is classified by. A structure in which particles falling along the inner walls of the fixed wing 606 and the guide cone 610 are introduced and dispersed into the classification air entering from the classification air intake port 605 via the slit 605A. It is what.

On the other hand, the rotary impeller 608A is a conical disk having a step on the outside at a position of an intermediate diameter, and a plurality of through holes 608B are arranged at equal pitches on the circumference of the step. meal was more dropped to the inside of the conical discs hole 608B or is adapted to be falling grit downwards. The diameter of the through hole 608B is about 5 to 10 mm, but is made as small as possible so as not to be blocked. The reason why the rotary impeller 608A is a conical disk having a step is that the coarse powder falling on the conical disk is surely discharged from the through hole 608B and passes through the through hole 608B from the inside between the rotary blades. This is to prevent passing through to the outside.
The classification is first performed with the primary swirl airflow, and further with the balance between the centrifugal force and the drag force of the air flowing inward in the secondary swirl airflow, and the fine particles having the required particle size pass through the fine powder outlet 609. It is taken out of the system as fine powder. On the other hand, coarse particles larger than the required particle size are subjected to the centrifugal force generated by the secondary swirling airflow, are spun off in the outer peripheral direction of the rotary impeller 608 and descend along the fixed wing 606, via the fixed wing 606. Although exposed to the classification air entering the inside and subjected to a dispersion action, the coarse particles continue to fall toward the coarse powder outlet 611. The dispersed fine particles are again carried together with the classification air into the secondary swirling airflow and classified. From this classification principle, the airflow classifier 6 can be used for both the classification step (S130) and the secondary classification step (S230).

As illustrated in FIG. 6, the centrifugal fluid crusher 8 has an outer peripheral ring 807 attached via a connecting member 809 inside a casing 808 that covers the main body portion. Reference numeral 810 denotes a pedestal, which pivotally supports a rotating dish 806 via a bearing 811. The rotating shaft 802 is driven by a power source such as an electric motor via a speed reduction mechanism or the like. At the center of the ceiling of the casing 808, a soil input pipe 812 is installed, and an opening 813 is provided so as to surround the input pipe 12, and a duct 814 is connected to the opening 813. The duct 814 is connected to the airflow classifier 6 (FIG. 5).
In this embodiment, the outer ring 807 is lined with a liner, and a large number of slits or small holes 815 are drilled through the wall surface. A side cover 816 is annularly provided between the bottom of the outer surface of the outer peripheral ring 807 and the inner surface of the casing 808, and an air introduction chamber 817 is defined between the side cover 816, the casing 808 and the outer surface of the outer peripheral ring 807. Thus, air can be introduced from the air introduction pipe 818. Note that the upper end of the side cover 816 is tightly fixed to the outer side surface of the outer peripheral ring 807.

Between the outer peripheral edge of the rotating dish 806 and the bottom inner peripheral surface of the outer peripheral ring 807, a clearance 819 of 10 to 30% of the minimum ball diameter of a ball 823 such as a steel ball is secured, and the bottom cover 820 is a clearance 819. It is arranged in an annular shape so as to cover the lower side of. In this embodiment, air can be introduced into the bottom cover 820 by drilling the side lower bar 816 or connecting an air introduction tube.
The bottom cover 820 and the air introduction chamber 817 are connected to a pipe line 821 for extracting and transporting fine particles of the collected soil classified by the airflow classifier 6, and the pipe line 821 is connected to the input pipe 812. Fine particles can be returned. Further , a scraper 822 is installed below the outer peripheral edge of the rotating dish 806 so that the fine particles dropped in the bottom cover 820 are gathered toward the connecting portion of the extraction pipe line 821.

When fine particles of the collected soil classified by the airflow classifier 6 are input from the input pipe 812 of the centrifugal fluid crusher 8 having the above-described configuration, the ball 823 is moved to the outer periphery along with the rotation of the rotating dish 806. By combining a circular motion that circulates between the inner wall surface of the ring 807 and the dish surface and a rotational motion around the central axis of the rotating dish 806, a spiral motion such as a rope is generated, thereby further pulverizing fine particles. Is what you do.
The air introduced into the air introduction chamber 817 and the bottom cover 820 from the air introduction pipe 818 flows into the pulverization chamber through the clearance 819, the slits or the small holes 815, and the duct 814 is accompanied with the powder generated by the pulverization. It enters the inside and is sent to the airflow classifier 6.

Now, according to the embodiment of the present invention configured as described above, the following operational effects can be obtained. That is, as shown in FIG. 1 (a), the soil collected in the contaminated soil collection step (S100) is dried in the drying step (S110), and the aggregation of the dried soil is further disintegrated (S120). It is possible to adjust the particle size of the dried soil to a particle size suitable for the classification of the soil according to the particle size in the subsequent classification step (S130). Therefore, by classifying the soil crushed in the pulverization step (S120) in the classification step (S130) according to the particle size, the moisture content of the collected soil, the aggregation of the soil, etc. Therefore, it is possible to avoid the occurrence of variation in classification accuracy due to the state of the soil and increase the classification accuracy. And among the soil classified in the classification process, the fine-grained soil is isolated in the subsequent management process (S140) (S150), and the remaining soil is returned to the soil collection site (S170), which is harmful. The soil with a small particle size containing most of the material is separated and collected, and the soil with a large particle size is returned to the collection site.
In addition, the soil is washed by the dry decontamination method through the above steps. Therefore, by-products such as contaminated water are not generated throughout the entire process. In addition, since necessary components (nutrients, etc.) of the soil are not washed away, the soil after washing is suitable for returning to the soil collection site for reuse. Further, by crushing and classifying the dried soil, it is not necessary to perform a process that requires a processing time such as pulverizing a large amount of soil, and the processing efficiency is increased.

If necessary, as shown in FIG. 2, among the soils classified in the classification step (S130), the finer soil size is further finely pulverized in the fine pulverization step (S220). The soil pulverized in the step (S220) is further classified according to the particle size in the subsequent secondary classification step (S230). And among the soil classified in the secondary classification step (S230), the fine-grained soil is isolated (S250) in the subsequent secondary management step (S240), and the remaining soil is returned to the soil collection site. In this way (S270), the small-sized soil containing most of the harmful substances is more precisely separated and collected, and the large-sized soil is returned to the collection site.
Also in this application example, soil washing is performed by a dry decontamination method throughout the entire process, and no by-products such as contaminated water are generated. Moreover, by performing fine pulverization on the fine particles containing the contaminated soil classified in the classification step (S130) (S220), the classification efficiency in all the steps is increased. Further, the remaining fine-grained soil from which the contaminated soil has been removed is not pulverized, so that the particle size suitable for reuse by returning to the soil collection site is maintained.

  In addition, since many contaminants adhere to the surface of the fine particles of the soil, the soil is not pulverized at once with a strong force but is polished in the pulverizing step (S220). If finely pulverized from the surface and separating the separated surface as fine particles by the secondary classification process, the fine particles with radioactive contaminants can be separated and isolated very efficiently. It becomes.

  Moreover, among the soil classified in the classification step (S130) or the secondary classification step (S230), the radiation dose of the remaining soil that is not isolated is measured (S160, S260), and the dose exceeds a predetermined value. By returning to the classification step (S130) or the secondary classification step (S230), it becomes possible to ensure the isolation and storage of the soil including the soil contaminated with the radioactive substance.

  In addition, the contaminated soil processing system 1 which concerns on embodiment of this invention is the impact-type crushing apparatus 4 which crushes the soil dried by the stirring drying apparatus 2 (FIG. 3) which dries soil (FIG. 3), and the stirring drying apparatus 2 ( 4) and an airflow classifier 6 (FIG. 5) for sorting the soil crushed by the impact crusher 4 according to the particle size. In addition, a centrifugal fluid crusher 8 (FIG. 6) that further crushes the finer grain size of the soil classified by the airflow classifier 6 as necessary is further included. And by using each of these devices, it is possible to efficiently perform the predetermined work in each of the above steps.

Furthermore, as imaged in FIGS. 7A and 7B, the devices 2 to 8 are mounted on the trailer bed so that the devices constituting the contaminated soil treatment system 1 can be moved. Or it is good also as comprising the special vehicle carrying each apparatus. In these special vehicles 10 etc., according to the size of each device, each device is mounted separately, or a plurality of types (or all) are mounted on one vehicle, and the soil collection site Thus, the predetermined work process is arranged so as to be carried out smoothly. In addition, when the contaminated soil treatment system 1 is installed in the soil collection site, foundation work or the like is not required, the construction period required for installation is short, and it is easy to move to a different soil collection site and operate.
In addition, there is no need for permission to install the contaminated soil treatment system 1, and it is possible to expect secondary effects such as obtaining local consent for installation.
In the embodiment of the present invention, as described above, the contaminated soil treatment method and the contaminated soil treatment system in the case where the soil is contaminated with radioactive materials have been described as examples, but the soil treatment technology for other pollution sources is also supported. It will be understood that this is possible.

1: Contaminated soil treatment system, 2: Stirrer / dryer, 4: Impact type crusher, 6: Airflow type classifier, 8: Centrifugal fluid crusher, S100: Contaminated soil collection step, S110: Drying step, S120: Crushing Process, S130: Classification process, S140: Management process, S150, S250: Secondary isolation process, S160, S260: Radioactivity level measurement process, S220: Fine grinding process, S230: Secondary classification process, S240: Secondary management process

Claims (7)

Contaminated soil collection process for collecting soil contaminated with radioactive materials ,
A drying step of drying the soil collected in the contaminated soil collection step;
A crushing step of breaking up agglomeration of soil dried in the drying step;
A classification step of separating the soil crushed in the pulverization step according to the particle size;
Among the soils classified in the classification step, an isolation step for isolating fine-grained soil ,
A radioactivity level measurement step for measuring the radiation dose of the remaining soil that is not isolated from the soil classified in the classification step,
In the radioactivity level measurement step, the remaining soil whose dose is less than or equal to a predetermined value is reused, and in the radioactivity level measurement step, if the dose exceeds a predetermined value, the process returns to the classification step, and the classification step The radioactive substance contaminated soil treatment method characterized by repeating the isolation step and the radioactivity level measurement step . Of the soil classified in the classification step, a finely pulverizing step of further finely pulverizing the particle size of the finely divided soil,
A secondary classification step of classifying the soil pulverized in the fine pulverization step according to the particle size;
Of the soil classified in the secondary classification step, a secondary isolation step of isolating fine-grained soil ;
A secondary radioactivity level measurement step for measuring the radiation dose of the remaining soil not isolated from the soil classified in the secondary classification step, and
In the secondary radioactivity level measurement step, the remaining soil whose dose is less than a predetermined value is reused, and when the secondary radioactivity level measurement step exceeds the predetermined value, the secondary classification step is performed. 2. The radioactive substance contaminated soil treatment method according to claim 1 , wherein the secondary classification step, the secondary isolation step, and the secondary radioactivity level measurement step are repeated . In the milling step, by peeling off the surface portion of the soil particles while polishing the soil, according to claim 2, wherein the fractionating surface portion of said separated該剥secondary classification step soil particles as fine Of radioactive material contaminated soil treatment. The radioactive substance-contaminated soil treatment method according to any one of claims 1 to 3, wherein in the drying step, the soil is dried to a predetermined dryness by supplying heated air. An agitation and drying device for drying the collected soil contaminated with radioactive material , and performing a drying process ;
An impact crushing device for crushing the soil dried by the stirring and drying device, and performing a crushing step ;
An airflow classifier that performs a classification process to classify the soil crushed by the impact crusher according to the particle size ;
A radiation measuring instrument that performs a radioactivity level measurement step that measures the radiation dose of the remaining soil that is not isolated after the isolation step that isolates fine-grained soil among the soil separated by the airflow type ball separator viewing including the door,
The remaining soil detected in the radioactivity level measurement step using the radiation measuring instrument is reused for the residual soil whose dose is less than a predetermined value, and the soil whose dose exceeds the predetermined value is returned to the airflow type ball separator. The radioactive substance- contaminated soil treatment system characterized by repeating the dividing step, the isolation step, and the radioactivity level measurement step . Among the soil classified by the airflow classifier , a centrifugal fluidized pulverizer for performing a fine pulverization step, which further finely pulverizes the particle size of finely divided soil ,
An air-flow classifier for performing a secondary classification step of classifying soil finely pulverized by the centrifugal fluid pulverizer according to the particle size;
A secondary radioactivity level measurement step of measuring the radiation dose of the remaining soil that is not isolated after the secondary isolation step of isolating the fine-grained soil among the soil separated by the airflow type ball separator only contains a radiation measuring instrument to perform,
The residual soil detected in the secondary radioactivity level measurement step using the radiation measuring instrument is reused and the secondary classification step is performed on the soil whose dose exceeds the predetermined value. 6. The radioactive substance- contaminated soil treatment system according to claim 5 , wherein the secondary classification step, the secondary isolation step, and the secondary radioactivity level measurement step are repeated after returning to the airflow type separation device. . Radioactive contaminated soil processing system according to claim 5 or 6 wherein each said device is configured to be movable.

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