JP2015087121A - Gravel decontamination facility, and gravel decontamination method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To efficiently decontaminate much gravel.SOLUTION: The gravel decontamination facility includes: a cylindrical body 21 that is cylindrical and has a plurality of through holes 21a penetrating the cylindrical body, and into which gravel to be processed is input; a turning mechanism 22 for turning the cylindrical body 21 about the axis; and a cleaning fluid tank 23 that surrounds the periphery of the cylindrical body 21 and reserves acid or alkaline cleaning fluid so as to dip at least a lower part of the cylindrical body 21.

Description

  The present invention relates to a gravel decontamination facility and a gravel decontamination method for decontaminating soil and debris contaminated by radioactivity.

  In order to decontaminate radioactively contaminated sites, removal of earth and sand, rubble (hereinafter referred to as sand gravel) and the like on the ground surface is performed. However, it is well known that the removed gravel is difficult to dispose of because it is contaminated by radioactivity.

Therefore, decontamination of collected gravel has been studied.
Patent Document 1 discloses a structure in which surface soil collected by scooping from soil is heated at 700 ° C. or higher for 1 hour, and vaporized cesium is adsorbed by a capturing means.

JP 2013-47611 A

However, in the configuration as described in Patent Document 1, the surface soil must be heat-treated at 700 ° C. or higher for 1 hour, which takes time. For this reason, it is not realistic to process a large amount of gravel.
An object of the present invention made there is to provide a gravel decontamination facility and a gravel decontamination method capable of efficiently decontaminating a large amount of gravel.

The present invention employs the following means in order to solve the above problems.
That is, the gravel decontamination equipment of the present invention has a cylindrical shape in which a plurality of through-holes penetrating the inside and outside of the cylinder are formed, and the gravel to be treated is thrown into the inside, and the cylinder is rotated around its axis. And a cleaning liquid tank that surrounds the cylindrical body and stores an acidic or alkaline cleaning liquid so as to immerse at least the lower part of the cylindrical body.
Accordingly, when the cylinder is rotated around the axis by the rotation mechanism, the gravel in the cylinder is agitated while being in contact with the cleaning liquid. Then, the fine particles adhering to the surface of the gravel are separated from the gravel and washed away, and are discharged out of the cylinder through the through hole of the cylinder. In this way, the gravel remaining in the cylinder can be decontaminated in a short time by washing the gravel and sieving it from the fine particles.
At this time, the cleaning effect is further enhanced by using acidic or alkaline cleaning liquid instead of water.

The gravel decontamination equipment of the present invention may further include a cleaning liquid spraying unit that sprays the cleaning liquid onto the gravel in the cylinder.
Thereby, the fine particle part adhering to the surface of the gravel can be more efficiently separated from the gravel.

Moreover, the gravel decontamination equipment of the present invention may further include a heating means for heating the cleaning liquid.
Thereby, the cleaning effect by an acidic or alkaline cleaning liquid increases.

Moreover, you may make it add the foaming agent which produces a bubble in the said washing | cleaning liquid to the gravel decontamination equipment of this invention.
Thereby, the separation of the fine particles from the gravel surface can be performed more efficiently. In addition, after the fine particle content is washed away in the cleaning liquid, the fine particle content rises together with the bubbles in the cleaning liquid, so that the fine particle content is easily recovered from the surface layer near the liquid surface of the cleaning liquid.

The present invention is a gravel decontamination method in the gravel decontamination equipment as described above, the step of throwing gravel into the cylinder, and the gravel while rotating the cylinder by the rotation mechanism And a step of contacting the cleaning liquid.
Thereby, the gravel in the cylinder is stirred while being in contact with the cleaning liquid. Then, the fine particles adhering to the surface of the gravel are separated from the gravel and washed away, and are discharged out of the cylinder through the through hole of the cylinder. In this way, the gravel remaining in the cylinder can be decontaminated in a short time by washing the gravel and sieving it from the fine particles.

  According to the present invention, a large amount of gravel can be efficiently decontaminated.

It is a figure which shows the whole structure of the gravel decontamination equipment concerning this embodiment. It is a perspective view which shows the washing | cleaning and classification apparatus which comprises the gravel decontamination equipment. FIG. 3 is a side sectional view of the cleaning / classifying apparatus shown in FIG. 2.

Hereinafter, an embodiment for carrying out a gravel decontamination facility according to the present invention will be described with reference to the accompanying drawings. However, the present invention is not limited only to this embodiment.
FIG. 1 is a diagram showing an overall configuration of a gravel decontamination equipment 10 according to the present embodiment, FIG. 2 is a perspective view showing a cleaning / classifying device 20 constituting the gravel decontamination equipment 10, and FIG. FIG. 3 is a side sectional view of the cleaning / classifying apparatus 20 shown.
The gravel decontamination equipment 10 shown in FIG. 1 performs decontamination processing of gravel by removing fine particles adhering to the surface of the gravel, and includes a cleaning / classifying device 20, a cleaning liquid supply unit 30, and fine particles. A fraction collection unit 40 and a waste cleaning liquid processing unit 50 are provided.

  As shown in FIGS. 2 and 3, the cleaning / classifying device 20 performs cleaning and classification of gravel, and includes a cylindrical body 21 in which a large number of through holes 21 a penetrating inside and outside are formed on a cylindrical peripheral surface. A plurality of rollers (rotating mechanism) 22 that rotatably supports the cylinder 21 and a cleaning liquid tank 23 provided so as to surround at least the lower part of the periphery of the cylinder 21 are provided.

  The through-hole 21a formed in the cylinder 21 is larger than the outer diameter of the fine particles to be removed from the gravel to be processed in the gravel decontamination equipment 10, and smaller than the outer diameter of the gravel to be removed after the processing. Is formed. Here, the shape of the through hole 21a is not questioned at all, and may be a polygonal shape or the like in addition to the circular shape. Furthermore, the cylindrical body 21 can be formed of a mesh material, and the opening of the mesh can be used as the through hole 21a.

  Two pairs of rollers 22 are disposed at both ends of the cylindrical body 21 in the direction of the central axis C with an interval smaller than the outer diameter of the cylindrical body 21. The cylinder 21 is placed on a pair of two rollers 22 and 22 at both ends. Each roller 22 has a columnar shape or a cylindrical shape having a central axis D parallel to the central axis C of the cylindrical body 21, and is rotated around the central axis D by a motor (not shown) or the like. The plurality of rollers 22 are rotationally driven in the same direction at a constant speed under the control of a control unit (not shown). As a result, the cylindrical body 21 placed on the plurality of rollers 22 is rotationally driven around the central axis C. Here, the cylindrical body 21 may be provided so that the central axis C extends in the horizontal direction, or provided so that the central axis C is inclined from the one end side 21b of the cylindrical body 21 toward the other end side 21c. Also good.

As shown in FIG. 1, a gravel supply chute 24 for supplying gravel to be decontaminated from a hopper (not shown) or the like is provided inside the cylinder 21 on one end side 21 b of the cylinder 21.
A discharge chute 25 that discharges gravel in the cylinder 21 is provided on the other end 21c of the cylinder 21.

  The cleaning liquid tank 23 stores the cleaning liquid L supplied from the cleaning liquid supply unit 30 so that at least the lower part of the cylindrical body 21 is immersed in the cleaning liquid L.

  The cleaning liquid supply unit 30 supplies the cleaning liquid L to the inside of the cylindrical tube body 21. Here, it is preferable that the cleaning liquid supply unit 30 includes an injection nozzle (cleaning liquid spraying means) 31 so as to spray the cleaning liquid L toward the gravel in the cylindrical body 21. Further, the cleaning liquid L is preferably circulated so that a part of the cleaning liquid L in the cleaning liquid tank 23 is sucked out by the pump 32 and jetted from the jet nozzle 31.

  Here, as the cleaning liquid L, it is preferable to use a solution of an organic acid such as oxalic acid, sodium hydroxide, potassium hydroxide or the like. Further, the cleaning liquid supply unit 30 may include a heater or the like for heating the cleaning liquid L as a heating unit in order to enhance the cleaning effect.

  Furthermore, it is preferable to add to the cleaning liquid L a foaming agent that foams the cleaning liquid L and generates bubbles in the cleaning liquid L in order to enhance the cleaning effect. As the foaming agent, when the cleaning liquid L is alkaline, for example, an ether carboxylic acid surfactant is preferably used. When the cleaning liquid L is acidic, a nonionic surfactant or the like is used. Is preferred.

In the cleaning / classifying device 20, the fine particle part collection unit 40 collects the fine particle part washed away from the surface of the gravel by the cleaning liquid L, so that a suction nozzle 41 is provided on the surface layer near the liquid surface of the cleaning liquid L in the cleaning liquid tank 23. Is provided. A pump or the like (not shown) is connected to the suction nozzle 41, and together with the cleaning liquid L in the cleaning liquid tank 23, the fine particles floating on the surface layer are sucked and collected.
In order to collect only the fine particle content, the fine particle content collecting unit 40 may be provided with a filter or the like for filtering the cleaning liquid L mixed with the fine particle content, and the filtered cleaning liquid L may be circulated in the cleaning liquid tank 23. .

When the cleaning effect of the cleaning liquid L in the cleaning liquid tank 23 falls, the waste cleaning liquid processing unit 50 extracts the cleaning liquid L in the cleaning liquid tank 23 and performs a process (neutralization process) necessary for disposal. Since radioactive cesium is generally present on the surface of the fine particles, the fine particles are removed using a coagulation sedimentation treatment or the like during the treatment.
After this treatment, the radioactive cesium dissolved in the water has a sufficiently low concentration (lower than the discharge standard), but is passed through a filling tank filled with an adsorbent such as zeolite as necessary.

In the gravel decontamination equipment 10 as described above, in order to perform the gravel decontamination process, first, gravel to be decontaminated is introduced into the cylindrical body 21 from the gravel supply chute 24.
Then, each roller 22 is driven to rotate about the central axis D by a motor (not shown) or the like. Then, the cylindrical body 21 placed on the plurality of rollers 22 is rotationally driven around the central axis C. Thereby, the gravel in the cylinder 21 is stirred by contact with the inner peripheral surface of the rotating cylinder 21.
The cleaning liquid L is stored in the cleaning liquid tank 23 so that at least the lower part of the cylindrical body 21 is immersed, and the cleaning liquid L is sprayed from the spray nozzle 31 toward the gravel in the cylindrical body 21.

Then, the gravel is agitated in the cleaning liquid L, and the cleaning liquid L is further sprayed from the spray nozzle 31, whereby fine particles attached to the surface of the gravel are separated from the surface of the gravel and washed into the cleaning liquid L.
At this time, the cleaning liquid L is heated, and the cleaning effect is enhanced by foaming the cleaning liquid L by adding a foaming agent.

  The fine particles separated from the gravel surface in this way pass through a large number of through holes 21a formed in the cylinder 21 and are discharged to the outside of the cylinder 21. Inside the cylinder 21, the inner diameter of the through hole 21a is exceeded. The gravel with a large outer diameter remains. In this way, the gravel and fine particles are screened.

In the cleaning liquid tank 23, the fine particles mixed in the cleaning liquid L together with the bubbles in the cleaning liquid L float on the surface layer of the cleaning liquid L, and the fine particle collection unit 40 together with the cleaning liquid L from the suction nozzle 41. To be recovered.
In the fine particle part collection unit 40, the recovered cleaning liquid L and the fine particle part are separated by a filter or the like to collect the fine particle part. Further, the cleaning liquid L that has passed through the filter or the like is returned to the cleaning liquid tank 23.

  When the gravel is washed and the fine particles are separated as described above, in the gravel remaining in the cylinder 21, the radiation dose is reduced and decontamination is performed. The debris after decontamination is discharged from the cylinder 21 to the outside by the discharge chute 25.

  When the cleaning performance of the cleaning liquid L is reduced by performing cleaning while circulating the cleaning liquid L, the cleaning liquid L is extracted from the cleaning liquid tank 23 and collected by the waste cleaning liquid processing unit 50. Then, processing necessary for disposal (neutralization processing) is performed. Since radioactive cesium is generally present on the surface of the fine particles, the fine particles are removed using a coagulation sedimentation treatment or the like during the treatment. After this treatment, the radioactive cesium dissolved in the water has a sufficiently low concentration (lower than the discharge standard), but is passed through a filling tank filled with an adsorbent such as zeolite as necessary.

As described above, according to the gravel decontamination equipment 10, fine particles are washed away from the surface of the gravel by bringing the gravel into contact with the cleaning liquid L while stirring the gravel in the cylinder 21, and the gravel is decontaminated in a short time. Can do. At this time, according to the amount of gravel to be processed, the size of the cylinder 21, the amount of the cleaning liquid L, the injection amount, and the like are appropriately set, so that even a large amount of gravel can be efficiently decontaminated. it can.
Moreover, the gravel after decontamination can be easily disposed of because the radiation dose is reduced. On the other hand, although the amount of fine particles washed away from the surface of the gravel is high, the volume can be significantly reduced as compared with the case where the entire gravel is disposed of, so that the disposal becomes easy.

Moreover, decontamination processing can be performed efficiently by using the cleaning liquid L that is acidic or alkaline instead of water.
In addition, the decontamination process can be performed more efficiently by heating the cleaning liquid L or spraying it on gravel.
Furthermore, the decontamination effect can be enhanced by adding a foaming agent to the cleaning liquid L to foam the cleaning liquid L.
Further, the fine particles in the cleaning liquid L can be floated together with the bubbles in the cleaning liquid L generated by foaming the cleaning liquid L, and the fine particles can be efficiently recovered.

(Other embodiments)
The present invention is not limited to the above-described embodiment described with reference to the drawings, and various modifications can be considered within the technical scope thereof.
For example, the cleaning liquid tank 23 is provided so as to surround only the lower portion of the cylindrical body 21, but the cleaning liquid tank 23 is provided so as to surround the entire cylindrical body 21 so that the entire cylindrical body 21 is immersed in the cleaning liquid. Also good.
Moreover, you may change suitably about the structure of the injection nozzle 31, the number of installation, etc. FIG.

In addition, the cleaning liquid L other than those exemplified above may be used as long as high cleaning ability can be exhibited.
Furthermore, in the said embodiment, although the foaming agent was added to the washing | cleaning liquid L, if it is in order to raise and collect the microparticles | fine-particle content in the washing | cleaning liquid L, for example, air will be sent in into the washing | cleaning liquid L from the bottom part of the washing | cleaning-liquid tank 23. By doing so, bubbles may be generated in the cleaning liquid L.

Further, the diameter of the through-hole 21a formed in the cylindrical body 21 may be appropriately set according to the diameter of the fine particles to be screened.
Furthermore, in the above-described embodiment, the cylindrical body 21 has a cylindrical shape, but may be a cylindrical shape, and is not limited to a cylindrical shape.

Furthermore, the gravel decontamination equipment 10 as described above can be mounted on a truck or trailer bed and can be moved. Thereby, mobility increases and decontamination work can be performed in various places.
In the above embodiment, the decontamination process is performed while circulating the cleaning liquid L, and the cleaning liquid L is recovered when the cleaning capacity of the cleaning liquid L is reduced. However, in the large-scale gravel decontamination equipment 10 and the like, While performing the decontamination process using the cleaning liquid L, a part of the cleaning liquid L may be collected from the cleaning liquid tank 23 while always supplying a new cleaning liquid L from the outside.
In addition to this, the configuration described in the above embodiment can be selected or changed to another configuration as appropriate without departing from the gist of the present invention.

DESCRIPTION OF SYMBOLS 10 Gravel decontamination equipment 20 Cleaning / classifying device 21 Cylindrical body 21a Through hole 22 Roller (rotating mechanism)
23 Cleaning liquid tank 30 Cleaning liquid supply part 31 Injection nozzle (cleaning liquid spraying means)
40 Particulate recovery unit 41 Nozzle 50 Waste cleaning liquid processing unit L Cleaning liquid

Claims (5)

A cylindrical body in which a plurality of through-holes penetrating the inside and the outside are formed, and a gravel to be processed is thrown into the inside,
A rotation mechanism for rotating the cylindrical body around an axis;
A cleaning liquid tank that surrounds the cylinder and stores an acidic or alkaline cleaning liquid so as to immerse at least the lower part of the cylinder,
Gravel decontamination equipment characterized by comprising.   The gravel decontamination equipment according to claim 1, further comprising cleaning liquid spraying means for spraying the cleaning liquid onto the gravel in the cylinder.   The gravel decontamination equipment according to claim 1 or 2, further comprising heating means for heating the cleaning liquid.   The gravel decontamination equipment according to any one of claims 1 to 3, wherein a foaming agent that generates bubbles is added to the cleaning liquid. A gravel decontamination method in the gravel decontamination equipment according to any one of claims 1 to 4,
Throwing gravel into the cylinder;
A step of bringing the cleaning liquid into contact with the gravel while rotating the cylindrical body by the rotation mechanism;
A gravel decontamination method comprising:

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