JP6027921B2 - Treatment method of contaminated soil - Google Patents

Description

The present invention relates to a method for treating contaminated soil comprising radioactive materials contaminated soil.

  Conventionally, as a method for treating contaminated soil, for example, there is a method of treating contaminated soil by mechanical friction cleaning with purification promoting grains (see, for example, Patent Document 1). In the technique described in Patent Document 1, fine soil (contaminated soil) having a particle size of less than 2 mm is put into a septic tank together with purification promoting particles having a particle size larger than that of fine soil, and washed with water while being supplied with washing water and stirred. As a result, contaminants on the surface of fine-grained soil were scraped off by the purification promoting grains.

  Conventionally, a method of treating mud contaminated soil is known (see, for example, Patent Document 2). In the technique described in Patent Literature 2, quick lime is mixed with mud-like contaminated soil and left to produce treated soil containing granular lumps, and this treated soil is reduced to a particle size range of 3 mm to 100 mm by the first classification means. Classification, the classified treated soil was crushed, the crushed treated soil was classified into a particle size range of 3 mm to 80 mm, and the classified treated soil was washed with water.

  Further, as a method for treating contaminated soil, a method of washing by adding a liquid to the soil is known (for example, see Patent Document 3). In the technique described in Patent Document 3, fine particles having the ability to adsorb pollutants are stirred together with soil and liquid, and the fine particles adsorbed contaminated soil are classified together with soil particles having a predetermined particle size or less.

Japanese Patent No. 4595099 Japanese Patent No. 4825649 JP 2011-183380 A

Method of treating contaminated soil comprising radioactive contaminants polluted soil is required. In the conventional method, volume reduction was insufficient.

  An object of this invention is to provide the processing method of the contaminated soil which can aim at the further volume reduction of the soil which concentrated the pollutant.

Method of treating contaminated soil of the present invention is a method for treating contaminated soil containing radioactive materials polluted soil contaminated by radioactive materials, are classified from the contaminated soil by using the first wet elutriation machine The process of crushing the treated soil having a particle size range exceeding the first classification point by the first crusher and the treated soil after being crushed by the first crusher are different from the first wet hydraulic classifier. A step of classifying using a second wet hydraulic classifier, a recovery step of recovering treated soil having a particle size range exceeding the second classification point classified by the second wet hydraulic classifier, and a recovered process Including a step of measuring the radioactive concentration of the soil and a step of crushing the collected treated soil with a second crusher when the collected radioactive concentration of the treated soil exceeds a reference value. It is characterized by.

In the method for treating contaminated soil of the present invention, using the first wet hydraulic classifier, the treated soil having a particle size range exceeding the first classification point classified from the contaminated soil is crushed by the first crusher. Thus, the clay mass contained in the contaminated soil can be thawed. Thereby, the surface area of the soil particle which can be contacted with a heavy metal and a radioactive contaminant can be increased, and the quantity of the contaminant adhering to a soil particle can be increased. Further, in the method for treating contaminated soil of the present invention, the treated soil after being crushed by the first crusher is classified using the second wet hydraulic classifier, so that a predetermined particle size to which a large amount of contaminants adhere is adhered. A range of soils can be isolated. Thereby, a pollutant can be concentrated and a contaminated soil can be reduced in volume. The crushing includes "be finely separated clumps or al soil particles content of soil particles" or "be comminuted soil particles themselves", "coarse fraction and fine fraction Specific examples of the former Examples of the latter include “polishing that separates coarse particles and fine particles from a lump of soil particles”, and “the polishing that removes the surface of the soil particles and granulates the fine particles”.

  The treatment method of the contaminated soil includes the treated soil having a particle size range equal to or lower than the first classification point classified using the first wet hydraulic classifier, and the second classified using the second wet hydraulic classifier. A step of classifying the treated soil having a particle size range equal to or smaller than the classification point of 2 using a centrifuge, and a treated soil having a particle size range exceeding the third classification point classified by the centrifuge. And a step of classifying again using a wet hydraulic classifier.

  According to such a method for treating contaminated soil, the treated soil classified using the first wet hydraulic classifier and the treated soil classified using the second wet hydraulic classifier are combined and centrifuged. Classifying using a separator and treating soil having a particle size range exceeding the third classification point classified by a centrifugal separator is again classified using the first wet hydraulic classifier, so a predetermined particle size range It can be separated by attaching pollutants to the surface of the soil particles. Thereby, a pollutant can be concentrated and a contaminated soil can be reduced in volume.

  The processing method of the contaminated soil includes a step of classifying the contaminated soil of the raw material at a fourth classification point that is larger than the first classification point using a mechanical classifier, and a classification using the mechanical classifier. Recovering the treated soil having a particle size range exceeding the fourth classification point, and treating the treated soil having a particle size range equal to or smaller than the fourth classification point classified using a mechanical classifier, And classifying with a hydraulic classifier.

  According to such a method of treating contaminated soil, since the contaminated soil of the raw material is classified in advance using a mechanical classifier, the classified treated soil is classified using the first wet hydraulic classifier. Thus, it is possible to more suitably separate soil having a predetermined particle size range to which a large amount of contaminants are attached. Thereby, a pollutant can be concentrated and a contaminated soil can be reduced in volume.

  Moreover, the processing method of the contaminated soil of this invention includes the process of collect | recovering the treated soil of the particle size range below the 3rd classification point classified using the centrifuge using a sedimentation concentration classifier. May be.

  According to such a method for treating contaminated soil, since it is collected using a sedimentation concentration classifier, it is possible to attach and separate contaminants on the surface of soil particles in a predetermined particle size range. Thereby, a pollutant can be concentrated and a contaminated soil can be reduced in volume.

  ADVANTAGE OF THE INVENTION According to this invention, the processing method of the contaminated soil which can aim at the further volume reduction of the soil which concentrated the contaminant can be provided.

It is the schematic which shows the contaminated soil processing apparatus with which the processing method of the contaminated soil which concerns on 1st Embodiment of this invention is applied. It is a flowchart which shows the procedure of the processing method of the contaminated soil which concerns on 1st Embodiment of this invention. It is the schematic which shows the contaminated soil processing apparatus with which the processing method of the contaminated soil which concerns on 2nd Embodiment of this invention is applied. It is a top view of a high mesh separator. It is a perspective view of a lock washer.

  Hereinafter, preferred embodiments of the present invention will be described with reference to the drawings. In addition, in each embodiment, the same code | symbol is attached | subjected about the part which has the same function, and the overlapping description may be abbreviate | omitted.

  The processing method of the contaminated soil which concerns on embodiment of this invention is applied to the processing of the contaminated soil containing the heavy metal contaminated soil contaminated with the heavy metal, or the radioactive contaminated soil contaminated with the radioactive substance. Examples of the heavy metal contained in the heavy metal contaminated soil include lead and cadmium. As a radioactive substance contained in radioactive substance contaminated soil, cesium is mentioned, for example.

(First embodiment)
First, a contaminated soil treatment apparatus to which the contaminated soil treatment method is applied will be described. In FIG. 1, the contaminated soil processing apparatus to which the processing method of the contaminated soil which concerns on 1st Embodiment is applied is shown. The contaminated soil treatment apparatus 1 shown in FIG. 1 has a mechanical classifier 2 (first classifier) that classifies the contaminated soil of the raw material in advance, and a first classifier that classifies the treated soil classified by the mechanical classifier 2. Wet hydraulic classifier 3 (second classifier), first crusher 4 for crushing treated soil classified by the first wet hydraulic classifier 3, and treatment crushed by the first crusher 4 And a second wet hydraulic classifier 5 (third classifier) for classifying soil.

  The contaminated soil treatment apparatus 1 includes a centrifuge 6 (fourth) that classifies the treated soil classified by the first wet hydraulic classifier 3 and the treated soil classified by the second wet hydraulic classifier 5 together. And a sedimentation concentration classifier 7 (fifth classifier) for recovering the treated soil classified by the centrifugal separator 6.

  The contaminated soil treatment apparatus 1 also includes a second crusher 8 that collects the treated soil that has been classified and removed by the second wet hydraulic classifier 5 and crushes the collected treated soil.

(Mechanical classifier)
The mechanical classifier 2 classifies the contaminated soil of the raw material in advance. The particle diameter of the soil classified by the mechanical classifier 2 can be set to, for example, 100 μm to 100 mm (large particle diameter, fourth classification point). The particle size classified by the mechanical classifier 2 is larger than the particle size classified by the wet hydraulic classifiers 3 and 5. As the mechanical classifier 2, for example, a vibrating screen (vibrating screen) or a trommel can be used. The processing capacity of the mechanical classifier 2 can be set to 150 t / h (large processing capacity), for example. The mechanical classifier 2 performs classification by separating solids having a predetermined size using a sieve.

  The mechanical classifier 2 of the present embodiment removes, for example, solids (coarse particles) having a particle diameter range exceeding 2 mm (fourth classification point) from the contaminated soil of the raw material. Solids having a particle size range exceeding 2 mm are collected and temporarily stored. The treated soil from which the solid matter having a particle size range exceeding 2 mm is removed is supplied to the first wet hydraulic classifier 3.

(First wet hydraulic classifier)
The first wet hydraulic classifier 3 classifies the treated soil classified by the mechanical classifier 2. The particle diameter of the soil classified by the first wet hydraulic classifier 3 can be, for example, 50 μm to 1000 μm (medium particle diameter, first classification point). The first wet elutriation machine 3, for example, may be used, such as high mesh separators or drum scrubber. The processing capacity of the first wet hydraulic classifier 3 can be set to, for example, 150 t / h (medium processing capacity or processing capacity comparable to that of the mechanical classifier 2). The first wet hydraulic classifier 3 performs classification while stirring and circulating the treated soil together with the liquid.

  The first wet hydraulic classifier 3 of the present embodiment removes, for example, solids having a particle size range exceeding 0.075 mm (first classification point) from the treated soil classified by the mechanical classifier 2. . The treated soil containing solids having a particle size range exceeding 0.075 mm is supplied to the first crusher 4. The treated soil having a particle size range of 0.075 mm or less is supplied to a centrifuge. In the first wet hydraulic classifier 3, treated soil having a particle size range of 0.075 mm or less, which is the first classification point, is supplied to the centrifugal separator 6, and 0.075 mm is added to the treated soil. A small amount of solids in the particle size range exceeding are included.

(First crusher)
The first crusher 4 crushes the treated soil classified by the first wet hydraulic classifier 3. As the first crusher 4, for example, a lock washer or a mixer-type mud breaker can be used. The first crusher 4 crushes the treated soil, thereby deflocculating a lump of soil particles including coarse particles and fine particles to subdivide the particles and increase the fine particles. The first crusher 4 mixes the treated soil and water and crushes the treated soil. The treated soil crushed by the first crusher 4 is supplied to the second wet hydraulic classifier 5.

(Second wet hydraulic classifier)
The second wet hydraulic classifier 5 classifies the treated soil crushed by the first crusher 4. The particle diameter of the soil classified by the second wet hydraulic classifier 5 can be, for example, 50 μm to 1000 μm (medium particle diameter, second classification point). The first wet elutriation machine 3, for example, may be used, such as high mesh separators or drum scrubber. The processing capacity of the second wet hydraulic classifier 5 can be set to, for example, 150 t / h (medium processing capacity, or the same processing capacity as the mechanical classifier 2).

  The second wet hydraulic classifier 5 of the present embodiment removes, for example, solids having a particle size range exceeding 0.075 mm (second classification point) from the treated soil classified by the first crusher 4. To do. Solids having a particle size range greater than 0.075 mm are collected and temporarily stored. The treated soil having a particle size range of 0.075 mm or less is supplied to the centrifuge 6. In the second wet hydraulic classifier 5, treated soil having a particle size range of 0.075 mm or less, which is the second classification point, is supplied to the centrifugal separator 6, and 0.075 mm is added to the treated soil. A small amount of solids in the particle size range exceeding are included.

(centrifuge)
The centrifugal separator 6 classifies the treated soil classified by the first wet hydraulic classifier 3 and the treated soil classified by the second wet hydraulic classifier 5. The particle diameter of the soil classified by the centrifuge 6 can be set to, for example, 10 μm to 500 μm (small particle diameter, third classification point). As the centrifuge 6, for example, a wet cyclone can be used. The processing capacity of the centrifuge can be, for example, 101.5 t / h (a small processing capacity). The centrifugal separator 6 is classified while circulating the treated soil together with the fluid.

The centrifugal separator 6 of the present embodiment is, for example, 0.075 mm (first) from the treated soil classified by the first wet hydraulic classifier 3 and the treated soil classified by the second wet hydraulic classifier 5. Solids having a particle size range exceeding 3 classification point) are removed. The treated soil containing solids having a particle size range exceeding 0.075 mm is supplied again to the first wet hydraulic classifier 3. The treated soil having a particle size range of 0.075 mm or less is supplied to the sedimentation concentration classifier 7. In general, the centrifugal separator 6 has a lower processing capacity than the wet hydraulic classifiers 3 and 5, but the classification accuracy is high. In the centrifugal separator 6, the solids having a particle size in excess of 0.075 mm, which is the third classification point, are removed again , so that the treatment by the first wet hydraulic classifier 3 and the second wet hydraulic classifier 5 is performed. it is possible to remove solid with a particle size range of greater than 0.075mm contained is a small amount of the soil. Thereby, the classification soil with a high classification accuracy and a particle size range of 0.075 mm or less can be obtained.

(Sedimentation concentration classifier)
The sedimentation concentration classifier 7 collects the treated soil classified by the centrifuge 6. The purpose of the sedimentation concentration classifier 7 is to collect all of the supplied treated soil. For example, particles having a particle size of 100 μm or less (very small particle size) are discharged together with water. As the sedimentation concentration classifier 7, for example, a wet thickener can be used. The sedimentation concentration classifier 7 stores the treated soil together with the liquid, and coagulates and precipitates the treated soil to separate it from the liquid.

  The sedimentation concentration classifier 7 of the present embodiment coagulates and settles the treated soil classified by the centrifugal separator 6 and separates and collects it. For example, the treated soil is recovered by agglomerating and precipitating solids having a particle size range exceeding 2 μm.

(Second crusher)
The second crusher 8 crushes the treated soil classified and removed by the mechanical classifier 2, and the treated soil classified and removed by the second wet hydraulic classifier 5 . For example, when the radioactivity concentration of the collected treated soil exceeds a reference value, the collected treated soil is crushed by the second crusher 8.

  As the 2nd crusher 8, a jet pump washing machine etc. can be used, for example. The second crusher 8 crushes the treated soil to polish the surface of the soil particles, scrape the particle surface, and increase the amount of fine particles. The second crusher 8 mixes the treated soil and water and crushes the treated soil. The treated soil crushed by the second crusher 8 is supplied to the second wet hydraulic classifier 5. Note that the treated soil crushed by the second crusher 8 may be supplied to the first wet hydraulic classifier 3.

(Processing method)
Next, a method for treating contaminated soil will be described with reference to FIG. First, the raw material radioactive contaminated soil (and / or heavy metal contaminated soil) is received (step S1: receiving process). Next, classifying the received input a contaminated soil by mechanical classifier 2 (Step S2: the first classification step). Next, the excess portion classified by the mechanical classifier 2 is recovered (step S3: first recovery step). The classified over fraction means treated soil having a particle size range exceeding the classification point.

  The under part classified by the mechanical classifier 2 is classified by the first wet hydraulic classifier 3 (step S4: second classification step). The classified under portion refers to treated soil having a particle size range equal to or lower than the classification point. Next, the over portion classified by the first wet hydraulic classifier 3 is crushed by the first crusher 4 (step S5: first crushing step). In step S5, the soil particles are crushed and crushed to separate the coarse and fine particles. The treated soil crushed in step S5 is supplied to the second wet hydraulic classifier 5.

  Next, the treated soil crushed by the first crusher 4 is classified by the second wet hydraulic classifier 5 (step S6: third classification step). Next, the over portion classified by the second wet hydraulic classifier 5 is recovered (step S7: second recovery step). In step S7, the treated soil having a particle size range exceeding the classification point is collected.

  Next, the under part classified by the first wet hydraulic classifier 3 and the under part classified by the second wet hydraulic classifier 5 are classified by the centrifugal separator 6 (step S8: fourth classification step). Next, the over portion classified by the centrifugal separator 6 is re-classified by the first wet hydraulic classifier 3 (step S9: re-classification step). The reclassification in step S9 may be performed in combination with the classification in step S4. The over portion reclassified in step S9 is crushed again by the first crusher 4 (step S5). The under part reclassified in step S9 is classified again by the centrifuge 6 (step S9).

Then recovered under fraction was classified in a centrifuge 6 thickener classifier 7 (Step S 10: recovering using thickener classifier). Here, the settled and separated treated soil is recovered, and the supernatant water is discharged.

  According to the contaminated soil treatment method of the present embodiment, the treated soil classified from the contaminated soil is crushed by the first crusher 4 using the first wet hydraulic classifier 3, so that the contaminated soil The clay lumps contained in can be thawed. Thereby, the particles of the treated soil can be subdivided to increase the total surface area of the particles, and the amount of contaminants attached to the soil particles can be increased.

  In the method for treating contaminated soil according to this embodiment, the treated soil after being crushed by the first crusher 4 and defatted is classified using the second wet hydraulic classifier 5, so that a large amount of contaminants are attached. Soil having a predetermined particle size range can be separated and recovered. Thereby, a pollutant can be concentrated and a contaminated soil can be reduced in volume.

  According to the method for treating contaminated soil of this embodiment, the treated soil for the under classified using the first wet hydraulic classifier 3 and the under treated for the under wet classified using the second wet hydraulic classifier 5 are used. The treated soil is combined and classified using the centrifugal separator 6, and the treated soil of the over-classified by the centrifugal separator 6 is classified again using the first wet hydraulic classifier 3, so the first wet type The excess treated soil that could not be removed by the hydraulic classifier 3 and the second wet hydraulic classifier 5 can be classified again and removed. Thereby, a pollutant can be concentrated and a contaminated soil can be reduced suitably.

  In the contaminated soil treatment method of the present embodiment, the contaminated soil of the raw material is classified in advance using the mechanical classifier 2, and the classified treated soil is classified by the first wet hydraulic classifier 3, so that the first Before putting the treated soil into the wet hydraulic classifier 3, large particles can be removed.

  According to the method for treating contaminated soil according to the present embodiment, since it is collected using the sedimentation concentration classifier 7, the contaminant is made highly concentrated by attaching the contaminant to the surface of the soil particle having a predetermined particle size range. The contained fine particles can be separated from the coarse particles with a low content of pollutants and recovered as contaminated soil. Thereby, a pollutant can be concentrated and a contaminated soil can be reduced in volume.

  According to the method for treating contaminated soil according to the present embodiment, the over fraction classified by the mechanical classifier 2 and the over fraction classified by the second wet hydraulic classifier 5 are respectively recovered. The soil with a low contamination concentration can be recovered. According to the method for treating contaminated soil of this embodiment, the volume of contaminated soil can be reduced, so that a large amount of soil with a low contamination concentration can be recovered.

(Second Embodiment)
Next, a method for treating contaminated soil according to the second embodiment will be described. FIG. 3 is a schematic diagram showing a contaminated soil treatment apparatus to which the contaminated soil treatment method according to the second embodiment is applied.

  The contaminated soil treatment apparatus 11 according to the second embodiment shown in FIG. 3 temporarily stores the collected contaminated soil (step S1: acceptance process). The contaminated soil treatment apparatus 11 is provided with a raw material hopper 12 to which the stored contaminated soil 101 is supplied. The stored contaminated soil 101 is transported, for example, by the backhoe 13 and put into the raw material hopper 12.

  The raw material hopper 12 is provided with a quantitative feeder, and the contaminated soil is discharged quantitatively. The contaminated soil discharged from the raw material hopper 12 is conveyed by the conveyor 14 and supplied to the drum scrubber 15.

(Drum scrubber)
The drum scrubber 15 thaws the supplied contaminated soil. The drum scrubber 15 has a cylindrical body that rotates about an axis. For example, the contaminated soil is put into a cylindrical body together with water, an iron ball, and the like. By rotating the cylindrical body, the contaminated soil, water, and iron ball inside are agitated, and the contaminated soil is defrosted. Thereby, the particle size of contaminated soil can be made small. The treated soil obtained by thawing with the drum scrubber 15 is supplied to a trommel (rotary sieve) 16.

(Trommel: mechanical classifier)
The trommel 16 classifies the supplied processing soil (step S2). The trommel 16 has a cylindrical body that rotates about an axis. A plurality of through holes are formed in the peripheral wall of the cylindrical body. The inner diameter of the through hole provided in the peripheral wall of the cylindrical body is 2 mm, for example. The treated soil is supplied to the inside of the cylindrical body, and the treated soil inside is agitated by rotating the cylindrical body. Soil particles having a particle size range of 2 mm or less are discharged from the holes in the peripheral wall of the cylindrical body. The treated soil having a particle size range of 2 mm or less is supplied to the high mesh separator 17.

  Among the treated soil supplied into the cylindrical body of the trommel 16, those having a particle size exceeding 2 mm are transported through the cylindrical body and discharged from the opening at the end in the longitudinal direction of the cylindrical body. The treated soil having a particle size range exceeding 2 mm is collected (step S3). The treated soil 102 obtained by collection is temporarily stored.

(High mesh separator: 1st wet hydraulic classifier)
As shown in FIG. 4, the high mesh separator (spiral classifier) 17 includes a screw conveyor 18 that is agitating and conveying blades. The screw conveyor 18 is supported so as to be rotatable around a rotation axis. A pool 19 is provided on the lower side of the screw conveyor 18, and water is stored in the pool 19. The lower side of the screw conveyor 18 is disposed in the water of the pool 19 that is a sedimentation layer. Further, the high mesh separator 17 can adjust the particle size distribution of particles that settle in the pool 19 by changing the rotational speed of the screw conveyor 18.

  In the high mesh separator 17, the water level in the pool 19 can be adjusted. The high mesh separator 17 can adjust the particle size distribution of particles that settle in the pool 19 by adjusting the water level of the pool 19.

The high mesh separator 17 has a configuration in which the amount of water supplied to the pool 19 can be adjusted. In the high mesh separator 17 , the particle size distribution of particles that settle in the pool 19 can be adjusted by adjusting the amount of water supplied to the pool 19.

  The pool 19 is continuously or intermittently supplied with water, and the overflowed water is discharged out of the pool 19.

  Soil particles containing particles of 2 mm or less that have passed through the trommel 16 are put into the pool 19. The soil particles thrown into the pool 19 settle in the water. As the screw conveyor 18 rotates about the rotating shaft 18a, the soil particles in the pool 19 are transported toward the transport direction, which is the right side of the drawing, and are simultaneously disturbed and washed in the water. Some impurities and fines in the soil particles are discharged out of the pool with the overflowed water. Along with the overflowed water, particles having a particle size range of, for example, 0.075 mm (classification point) or less are supplied to the cyclone classifier 27.

  A bucket conveyor 20 is provided at the end of the screw conveyor 18 in the direction of soil particle conveyance. The bucket conveyor 20 has a bucket 20a that rotates around a predetermined rotation axis. The bucket 20a rotates around a predetermined rotation axis extending in the direction in which the soil particles are conveyed, and scrapes up the soil particles transferred through the pool 19.

  A dewatering screen (dehydrator) 21 is provided further to the side of the bucket 20a. The soil particles picked up by the bucket 20 a are discharged onto the dehydration screen 21. The dewatering screen 21 has a vibrating screen and removes moisture while conveying soil particles. The soil particles dehydrated by the dehydration screen 21 are supplied to the lock washer 22.

(Lock washer: 1st crusher)
As shown in FIG. 5, the lock washer 22 has a storage tank 23 to which processing soil and water are supplied. The storage tank 23 is provided with a pair of rotating shafts 24. A blade portion 25 is provided on the peripheral surface of the rotating shaft 24 so as to project outward in the radial direction. The pair of rotating shafts 24 are rotated in different rotation directions. By rotating the pair of rotating shafts 24, the treated soil in the storage tank 23 is agitated, and the treated soil sandwiched between the blade portions 25 rubs against each other, thereby adhering to the surface of the soil particles. The fine particles are deflated and the particles become smaller.

(High mesh separator: second wet hydraulic classifier)
The high mesh separator 26 has the same configuration as the high mesh separator 17 described above. The excess portion classified by the high mesh separator 26 is collected. The treated soil 103 obtained by the collection is stored. The radioactive concentration of the collected treated soil 103 is measured. When the radioactivity concentration is below the standard value, it is effectively used as purified sand / gravel. If the radioactivity concentration exceeds the reference value, the recovered treated soil 103 may be returned to the high mesh separator 26 and processed again.

(Cyclone classifier: centrifuge)
The cyclone classifier (liquid cyclone) 27 classifies the under part classified by the high mesh separators 17 and 26. The cyclone classifier 27 has a tapered cylindrical body. The cylindrical body of the cyclone classifier 27 has a smaller inner diameter as it goes downward. The cyclone classifier 27 is supplied with liquid (for example, water) and treated soil. The supplied liquid and the treated soil are swirled in the cylindrical body, and those having a small particle diameter are discharged from the center upper part of the cylindrical body, and those having a large particle diameter descend along the inner peripheral wall surface of the cylindrical body. It is discharged from the lower end of the body. The over portion classified by the cyclone classifier 27 is supplied to the high mesh separator 17 and classified again. The under portion classified by the cyclone classifier 27 is supplied to the thickener 28.

(Thickener: sedimentation concentration classifier)
The thicker 28 is supplied with the under part classified by the cyclone classifier 27, and collects the coagulated sediment particles. The thickener 28 has a treated soil and a sedimentation layer to which water is supplied. Aggregated sediment is supplied to the sedimentation layer, and the soil particles are aggregated and collected. The supernatant water of the sedimentation layer is treated by the water treatment column 29 and discharged outside the apparatus. The treated soil settled and collected in the sedimentation layer is supplied to the dehydrator 30. The treated soil 104 (dehydrated sludge) dehydrated by the dehydrator 30 is stored and temporarily placed.

(Jet pump washer: second crusher)
When the radioactive concentration of the overlying treated soil 103 classified by the high mesh separator 26 exceeds the reference value, the treated soil may be cleaned by the jet pump washing machine 31. By generating a water stream ejected from a jet pump in a storage tank for storing water and treated soil, the treated soil is polished and the particle surface is scraped off. The treated soil from which the particle surface has been scraped is returned to the high mesh separator 26 and treated again.

(Mass balance of treated soil)
Next, an example is demonstrated with a mass balance about the processing flowchart of the processing soil in the processing method of the contaminated soil of this embodiment. As the contaminated soil 101 supplied to the drum scrubber 15, 100 wt% of the contaminated soil 101 having a radioactivity concentration of 12,000 Bq / kg is supplied to the drum scrubber 15.

  As an over fraction classified by the trommel 16, a radioactive concentration of 1,500 Bq / kg and a gravel of 2 mm or more which is 10 wt% treated soil 102 is collected. As an under part classified by the trommel 16, 90 wt% of treated soil having a radioactivity concentration of 13,170 Bq / kg is supplied to the high mesh separator 17. The breakdown of the 90 wt% treated soil supplied to the high mesh separator 17 is 70 wt% sand and 20 wt% mud. In the trommel 16, the soil having a particle size exceeding 2 mm is recovered as an excess. The radioactive concentration of this treated soil was 1,500 Bq / kg. However, if a lower radioactive concentration is desired, the classification point may be increased.

  As an under part classified by the high mesh separator 17, a treated soil having a radioactive concentration of 35,000 Bq / kg and 25 wt% is supplied to the cyclone classifier 27. The breakdown of the 25 wt% treated soil supplied to the cyclone classifier 27 is 10 wt% sand and 15 wt% mud. In the high mesh separator 17, the under part having a particle size of 0.075 mm or less is discharged. The radioactive concentration of the discharged treated soil was 35,000 Bq / kg. However, if a higher radioactive concentration is desired, the classification point may be made smaller.

  As the over-classification by the high mesh separator 17, the treated soil having a radioactive concentration of 6,800 Bq / kg and 65 wt% is supplied to the lock washer 22. The breakdown of the 65 wt% treated soil supplied to the lock washer 22 is 60 wt% sand and 5 wt% mud. In the lock washer 22, for example, new fine particles that are particles having a particle size of 0.075 mm or less are granulated by the crushing step.

  Further, 10 wt% of treated soil having a radioactivity concentration of 29,540 Bq / kg is supplied to the cyclone classifier 27 as the under part classified by the high mesh separator 26. The breakdown of the 10 wt% treated soil supplied from the high mesh separator 26 to the cyclone classifier 27 is 5 wt% sand and 5 wt% mud. The 10 wt% treated soil is granulated by the lock washer 22. In addition, particles of 0.075 mm or less are included. As an over fraction classified by the high mesh separator 26, the radioactive concentration of 2,070 Bq / kg and the sand which is the treated soil 103 of 70 wt% is recovered. Thereby, as the total amount of the treated soil 105 collected, the treated soil 105 having a radioactivity concentration of 2,000 Bq / kg and 80 wt% is collected. The breakdown of the collected 80 wt% treated soil 105 is 10 wt% for gravels of 2 mm or more and 70 wt% for sand of 0.075 or more and 2 mm or less.

  The cyclone classifier 27 is fed with the under part classified by the high mesh separators 17 and 26. The treated soil sent to the cyclone classifier 27 is mainly one having a particle size of 0.075 mm or less, but actually includes soil having a particle size exceeding 0.075 mm. The cyclone classifier 27 classifies again.

  After classification by the high mesh separator 17, mud which is a treated soil of 15 wt% with a radioactive concentration of 57,000 Bq / kg is supplied to the thickener 28 as the under part classified by the cyclone classifier 27. After the classification in the high mesh separator 17, sand that is 10 wt% treated soil having a radioactive concentration of 2,070 Bq / kg is supplied to the high mesh separator 17 as an over fraction classified by the cyclone classifier 27. Classify again.

  After the classification with the high mesh separator 26 and the desulfurization with the lock washer 22, the radioactivity concentration is 57,000 Bq / kg as 5% by weight of the treated soil as the under part classified by the cyclone classifier 27. A mud is supplied to the thickener 28. After the classification with the high mesh separator 26 and after the mud removal with the lock washer 22, the radioactivity concentration is 2,070 Bq / kg and the treated soil is 5 wt% as the over fraction classified by the cyclone classifier 27. A certain sand is supplied to the high mesh separator 17 and classified again.

After being aggregated and settled by the thickener 28, it is supplied to the dehydrator 30 for dehydration, and the treated soil 104 having a radioactivity concentration of 57,000 Bq / kg and 20 wt% is recovered as dehydrated sludge.

  According to the method for treating contaminated soil of this embodiment, the volume of contaminated soil 101 having a radioactivity concentration of 12,000 Bq / kg is reduced to 20 wt% of treated soil 104 having a radioactivity concentration of 57,000 Bq / kg. I was able to. Further, the treated soil 105 having a radioactive concentration of 2,000 Bq / kg and 80 wt% can be effectively used. According to the contaminated soil treatment method of the present embodiment, it is possible to reduce the amount of treated soil in which radioactive substances are concentrated.

  In the present embodiment, the radioactive concentration of the treated soils 102, 103, and 104 and the amount of treated soil can be adjusted by adjusting the classification points. Specifically, the radioactive concentration of the treated soil 102 can be further reduced by increasing the classification point of the trommel 16. However, the amount of the treated soil 102 is also reduced. Therefore, it is preferable to adjust the classification point of the trommel 16 while measuring the radioactive concentration of the treated soil 102 and the amount of the treated soil 102.

  By making the classification points of the high mesh separators 17 and 26 smaller, the radioactive concentration of the treated soil 104 can be made larger. However, the amount of treated soil 104 becomes smaller. As a result, the total amount of radioactive material that can be removed by the treated soil 104 may be reduced. On the other hand, the amount of the treated soil 103 is increased, but the radioactivity concentration may be increased. Therefore, it is preferable to adjust the classification points of the high mesh separators 17 and 26 while measuring the radioactive concentration of the treated soil 103 and the amount of the treated soil 103.

  As mentioned above, although the case of the radioactive contamination soil was demonstrated about the suitable embodiment of this invention, this invention is not limited to the said embodiment, The case of heavy metal contamination soil is the same. For example, the classification point in each classifier can be changed as appropriate.

1,11 ... Contaminated soil treatment device 2 ... Mechanical classifier (first classifier)
3. First wet hydraulic classifier (second classifier)
4 ... 1st crusher 5 ... 2nd wet hydraulic classifier (3rd classifier)
6. Centrifuge (fourth classifier)
7 ... Precipitation concentration classifier (fifth classifier)
8 ... Second crusher 12 ... Raw material hopper 13 ... Backhoe 14 ... Conveyor 15 ... Drum scrubber 16 ... Trommel (mechanical classifier, first classifier)
17 ... High mesh separator (first wet hydraulic classifier, second classifier)
18 ... Screw conveyor 19 ... Pool 20 ... Bucket conveyor 20a ... Bucket 21 ... Dehydration screen 22 ... Lock washer (first crusher)
DESCRIPTION OF SYMBOLS 23 ... Reservoir 24 ... Rotating shaft 25 ... Blade | wing part 26 ... High mesh separator (2nd wet hydraulic classifier, 3rd classifier)
27 ... Cyclone classifier (centrifugal separator, fourth classifier)
28 ... Thickener (sediment concentration classifier, fifth classifier)
29 ... Water treatment column 30 ... Dehydrator 31 ... Jet pump washer (second crusher)
101 ... Contaminated soil (raw material)
102, 103, 104 ... treated soil

Claims (4)

A method for treating contaminated soil including radioactive material contaminated soil contaminated with radioactive material,
Crushing the treated soil having a particle size range exceeding the first classification point classified from the contaminated soil using the first wet hydraulic classifier with the first crusher;
Classifying the treated soil after being crushed by the first crusher using a second wet hydraulic classifier different from the first wet hydraulic classifier;
A recovery step of recovering treated soil having a particle size range exceeding the second classification point classified by the second wet hydraulic classifier;
Measuring the radioactivity concentration of the recovered treated soil;
Crushing the collected treated soil with a second crusher when the radioactivity concentration of the collected treated soil exceeds a reference value, and a method for treating contaminated soil, . Treated soil having a particle size range below the first classification point classified using the first wet hydraulic classifier, and below the second classification point classified using the second wet hydraulic classifier A process of classifying the treated soil in a particle size range using a centrifuge;
The method further comprises the step of classifying the treated soil having a particle size range exceeding the third classification point classified by the centrifugal separator again using the first wet hydraulic classifier. A method for treating contaminated soil as described in 1. A step of pre-classifying the contaminated soil of the raw material using a mechanical classifier at a fourth classification point that is larger than the first classification point;
A step of recovering treated soil having a particle size range exceeding the fourth classification point classified using the mechanical classifier;
And a step of classifying the treated soil having a particle size range equal to or smaller than the fourth classification point classified using the mechanical classifier using the first wet hydraulic classifier. The processing method of the contaminated soil of Claim 1 or 2.   The contamination according to claim 2, further comprising a step of collecting the treated soil having a particle size range equal to or smaller than a third classification point classified using the centrifugal separator using a sedimentation concentration classifier. Soil treatment method.

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