JP2013169504A - Contaminated soil treatment apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a contaminated soil treatment apparatus with a structure capable of efficiently and safely separating radioactive substances (or, heavy metals) from soil contaminated by the radioactive substances (or, the heavy metals).SOLUTION: A contaminated soil treatment apparatus 100 includes: a main vessel 1 in which contaminated soil is charged and from a bottom of which treated soil is discharged; a first soil raising pipe 2 opening at both upper and lower ends thereof, and arranged in the main vessel 1 in a vertical direction; a second soil raising pipe 3 opening at both upper and lower ends thereof, arranged at a bottom part in the main vessel 1 in a vertical direction in a state such that a part thereof is inserted in a lower end part of the first soil raising pipe 2, and having a smaller diameter than the first soil raising pipe 2; a first air supply pipe 4 for supplying air to the first soil raising pipe 2; a second air supply pipe 5 for supplying air to the second soil raising pipe 3; a third air supply pipe 6 for supplying air to the bottom part in the main vessel 1 below the second soil raising pipe 3; and a water supply pipe 7 for supplying water to the bottom part of the main vessel 1 below the second soil raising pipe 3.

Description

  The present invention relates to a technique for separating radioactive substances or heavy metals from contaminated soil in which radioactive substances or heavy metals are accumulated.

  Techniques for efficiently and safely separating radioactive materials from soil contaminated with radioactive materials have not been established. If radioactive substances can be efficiently separated from contaminated soil, for example, much of the soil removed from the ground surface can be backfilled in its original location. Further, since the volume of contaminants containing radioactive substances is greatly reduced, the storage space can be reduced accordingly.

  On the other hand, although the technical field is different, the present inventor has developed an apparatus for cleaning the sand settling into the sewage treatment plant (see, for example, Patent Documents 1 and 2). Patent Documents 1 and 2 describe a sedimentation washing apparatus, which includes a treatment tank into which sewage containing sedimentation is introduced, a levitation pipe provided vertically in the treatment tank and supplied with air, and a levitation pipe. Is a device comprising a large number of separation facilitating pieces that rise by an upward flow. The sewage containing the settling sand thrown into the treatment tank is agitated and washed in the levitation pipe by the separation promoting piece, air and washing water by supplying air into the levitation pipe. By this stirring and washing, the SS component having a small specific gravity mixed in the settling sand is separated and discharged from the upper part of the treatment tank.

Japanese Patent No. 3396684 Japanese Patent No. 4678627

  It is known that clay contained in soil has a property of adsorbing radioactive substances and heavy metals (holding and fixing these substances firmly between layers of clay minerals constituting the clay). Therefore, if the clay which adsorb | sucked the radioactive substance can be isolate | separated from soil, a radioactive substance will be isolate | separated from soil with clay. Here, it is considered that it is possible to some extent to separate the clay adsorbed with the radioactive material from the soil by introducing the contaminated soil into a sedimentation washing apparatus as described in Patent Documents 1 and 2.

  However, since the particle size of clay is small, it is difficult to efficiently separate clay from soil even when using the cleaning treatment apparatus described in Patent Documents 1 and 2. In addition, radioactive substances are not only adsorbed on clay, but also are attached to the surface of particles such as sand and gravel contained in soil. Therefore, the radioactive material must be removed from the surface of particles such as sand and gravel contained in the soil, but the cleaning treatment apparatus described in Patent Documents 1 and 2 has insufficient capability. Moreover, the particle size of the sedimentation sand contained in the sewage is often about 2 mm, and the variation in particle size is relatively small. In contrast, most of the soil contains gravel with a particle size exceeding 2 mm, and as described above, the particle size of the clay is small, that is, the particle size of the particles constituting the soil varies. .

  The present invention has been made in view of the above circumstances, and the problem to be solved is to efficiently and safely separate the radioactive substance (or heavy metal) from the soil contaminated with the radioactive substance (or heavy metal). It is providing the contaminated soil processing apparatus provided with the structure which can do.

  The present invention is a contaminated soil treatment apparatus for separating radioactive substances or heavy metals from contaminated soil containing clay and containing radioactive substances or heavy metals. The contaminated soil treatment apparatus includes a main body container into which the contaminated soil is introduced and treated soil is discharged from the bottom, and a first earthen pipe that is open in the upper and lower ends and arranged vertically in the main body container. The upper and lower ends are both open and partly inserted into the lower end of the first earthing pipe, and the first earthing pipe having a smaller diameter than the first earthing pipe disposed vertically at the bottom of the main body container. 2 than the 2nd earthing pipe, the 1st air supply pipe for supplying air to the 1st earthing pipe, the 2nd air supply pipe for supplying air to the 2nd earthing pipe, and the 2nd earthing pipe A third air supply pipe for supplying air to the bottom part in the lower main body container; and a water supply pipe for supplying water to the bottom part in the main body container below the second earthing pipe. It is characterized by that.

  According to the present invention, radioactive substances (or heavy metals) can be efficiently and safely separated from soil contaminated with radioactive substances (or heavy metals).

It is a longitudinal cross-sectional view of the contaminated soil processing apparatus which concerns on 1st Embodiment of this invention. It is AA sectional drawing and BB sectional drawing of FIG. It is CC sectional drawing and DD sectional drawing of FIG. It is a top view of the discharge port part of the 2nd earth-lifting pipe shown in FIG. 1, and the cross-sectional detail drawing of the earth and sand mixing blade. It is a longitudinal cross-sectional view which shows other embodiment of the 1st unloading pipe shown in FIG. It is a longitudinal cross-sectional view which shows the modification of the contaminated soil processing apparatus shown in FIG.

  Hereinafter, embodiments for carrying out the present invention will be described with reference to the drawings. The present invention can be applied not only to soil containing clay, but also to rubble containing clay (debris of a destroyed building, etc.). That is, debris can be used as a decontamination target. When the size of rubble is large, the rubble is crushed to a predetermined particle size (dimension) or less as a pretreatment, and the crushed rubble is put into the contaminated soil treatment apparatus of the present invention, so that the radioactive material from the contaminated rubble is radioactive. Substances can be removed.

  In the following description, cesium of radioactive substances is described as a substance to be separated and removed. However, according to the present invention, radioactive substances other than cesium, such as cobalt and strontium, can also be removed from soil or the like. In addition, heavy metals such as lead, arsenic, and mercury can be removed.

(Configuration of contaminated soil treatment equipment)
A contaminated soil treatment apparatus 100 according to the first embodiment of the present invention will be described with reference to FIGS. As shown in FIG. 1, the contaminated soil treatment apparatus 100 of the present embodiment includes a main body container 1, an earthing pipe (first earthing pipe 2, second earthing pipe 3), an air supply pipe (first air supply pipe 4, first 2 air supply pipe 5, third air supply pipe 6), water supply pipe 7, drainage pipe 8 and the like.

(Main body container)
The main body container 1 is a rectangular container, and its lower part is an inverted quadrangular pyramid whose volume gradually decreases as it goes vertically downward. That is, the main body container 1 includes a main body portion 21 having a substantially constant cross-sectional area in the vertical direction except for the input portion 1a, and an inverted quadrangular pyramid-shaped lower portion 22 whose volume gradually decreases in the vertical direction. . The main body container may be a cylindrical container, and the lower part may have an inverted conical shape whose volume gradually decreases as it goes vertically downward. On the side surface of the main body container 1 and at the upper end thereof, a contaminated soil charging portion 1a is provided. Further, a treated soil discharge pipe 13 is attached vertically downward to the bottom of the main body container 1. The contaminated soil is poured downward into the main body container 1 from the inlet 1b provided at the upper end of the inlet 1a.

  A plurality of drain pipes 8 (8a to 8e) are attached to the side surface of the main body portion 21 of the main body container 1 so that the directions are horizontal. In the present embodiment, the three drain pipes 8a to 8c are attached to the side surface of the main body 21 opposite to the charging section 1a with the heights of the drain pipes 8a to 8c being mutually different, and the two drain pipes 8d and 8e are mutually high. In other words, it is attached to the side surface of the main body portion 21 on the input portion 1a side. The drain pipes 8d and 8e are located below the input part 1a. The mounting height of the drain pipes 8b and 8c is the same as the mounting height of the drain pipes 8d and 8e arranged opposite to them. By the plurality of drain pipes 8 (8a to 8e), drainage is possible from an arbitrary level (height) in the main body portion 21. In addition, the drain pipe attached to the main body container 1 does not necessarily need to be plural, and may be one (the drain part from the main body container 1 may be one place).

  Moreover, the electric drain valve 14 is attached to each of the drain pipes 8a to 8e. The electric drain valve 14 is a valve whose opening degree can be adjusted. That is, the amount of drainage can be adjusted by adjusting the opening degree of the electric drain valve 14. The drain valve attached to the drain pipes 8a to 8e may be an air operated valve or a manual valve. In addition, when an automatic valve such as an electric valve is used, it is not always necessary to adjust the opening.

  A water supply pipe 7 is attached to the discharge pipe 13 attached to the bottom of the main body container 1 in a horizontal direction. With this water supply pipe 7, water can be supplied to the bottom part in the main body container 1 below the second pumping pipe 3. For example, an automatic valve (not shown) such as an electric valve is attached to the water supply pipe 7.

  A third air supply pipe 6 is attached to the discharge pipe 13 attached to the bottom of the main body container 1 together with the water supply pipe 7 so that the direction is horizontal. With this third air supply pipe 6, air can be supplied to the bottom part in the main body container 1 below the second earthing pipe 3. For example, an automatic valve (not shown) such as an electric valve is attached to the third air supply pipe 6. Here, in this embodiment, the direction (air discharge direction) of the air discharge port 6a of the third air supply pipe 6 is horizontal. However, the direction of the air discharge port 6a is not necessarily horizontal.

  An electric discharge valve 15 is attached to a portion of the discharge pipe 13 downstream of the position where the water supply pipe 7 and the third air supply pipe 6 are connected to the discharge pipe 13. The treated soil is discharged from the bottom of the main body container 1 by opening the electric discharge valve 15. The discharged treated soil is transported by, for example, the container 51 and backfilled after it is confirmed that the radiation dose is below a predetermined value. Note that the discharge valve attached to the discharge pipe 13 may be an air operated valve or a manual valve.

(Pavement pipe)
<First unloading pipe>
A cylindrical first earthen pipe 2 is arranged vertically in the center of the main body container 1 in the main body 21. As for the 1st earthen pipe 2, the upper and lower ends are all opened. The first earthmoving pipe 2 includes a long cylindrical portion 23 and a pyramid-shaped umbrella portion 24 provided at the lower end of the cylindrical portion 23. A plurality of agitation promoting balls 14 are placed in the first earthing pipe 2. The stirring promoting ball 14 is, for example, a sphere having a diameter of 10 mm and has a specific gravity of about 1.01 to 1.1. The umbrella portion 24 may be conical.

  A fall prevention plate 25 for preventing the stirring promoting ball 14 from falling is attached to the lower end opening of the umbrella portion 24. In this embodiment, a plurality of flat bars (flat bars) are combined to form the fall prevention plate 25. By making the interval between adjacent flat steels smaller than the size (diameter) of the stirring promotion ball 14, the stirring promotion ball 14 is prevented from falling out of the first earthing pipe 2.

  The first air supply pipe 4 is connected to the lower side surface of the cylindrical portion 23 of the first earthing pipe 2 with the direction thereof being horizontal. The first air supply pipe 4 is for supplying air to the first earthing pipe 2. Although the direction of the air discharge port 4a of the first air supply pipe 4 is horizontal, the air discharge port 4a extends to the inside of the first earthing pipe 2 and the direction (air discharge direction). May be vertically upward.

  A separation box 9 is provided at the upper end portion of the first earthing pipe 2 so as to surround the discharge port 2 a of the first earthing pipe 2. The separation box 9 is for separating the stirring promoting balls 14 and the earthing, and is formed, for example, by combining a plurality of flat bars in a basket shape. By making the interval between adjacent flat steels smaller than the dimension (diameter) of the stirring promotion ball 14, the stirring promotion ball 14 is prevented from coming out of the separation box 9.

  The bottom of the separation box 9 and the lower part of the cylindrical portion 23 of the first earthing pipe 2 are communicated with each other by a stirring promotion ball return pipe 10. The bottom surface 9 a of the separation box 9 is an inclined surface that is inclined toward the stirring promoting ball return pipe 10. The agitation promoting ball return pipe 10 is for returning the agitation promoting ball 14 discharged from the discharge port 2 a of the first earthing pipe 2 by air lift to the lower part of the first earthing pipe 2.

<Second unloading pipe>
In a state in which a part is inserted in the umbrella portion 24 constituting the first earth-pumped pipe 2, the second earth-pumped pipe 3 is arranged vertically on the bottom of the main body container 1. The second pumping pipe 3 is coaxial with the first pumping pipe 2, and the diameter (outer diameter) of the second pumping pipe 3 is smaller than the diameter of the first pumping pipe 2 (the inner diameter of the cylindrical portion 23). . Moreover, as for the 2nd earth-pumping pipe 3, the upper and lower ends are all open.

  Further, the second air supply pipe 5 is connected to a substantially central side surface in the longitudinal direction of the second earthing pipe 3 in a horizontal direction. The second air supply pipe 5 is for supplying air to the second earthing pipe 3. As with the first air supply pipe 4, the direction (air discharge direction) of the air discharge port 5a of the second air supply pipe 5 is horizontal. However, the air discharge port 5a may be extended to the inside of the second earthmoving pipe 3, and the direction thereof may be vertically upward. When extending the air outlet 5a of the second air supply pipe 5 to the inside of the second earthing pipe 3, the diameter (outer diameter) of the second air supply pipe 5 is set to the second earthing pipe so as not to hinder the rise of the soil. It is better to make the diameter (inner diameter) of 3 as small as possible.

  As shown in FIG. 4A, a plan view of the discharge port portion of the second earthing pipe 3 is provided at the discharge port (upper end) of the second earthing pipe 3 with the fall prevention member 31 for preventing the stirring promoting ball 14 from falling. Is attached. In the present embodiment, flat steel (flat bar) is joined in a cross shape to form a fall prevention member 31, and this fall prevention member 31 is fitted into the discharge port of the second earthing pipe 3 and fixed.

(Sand sand mixing blade-like member)
A plurality of earth and sand mixing blade-like members 11 for dividing the downward flow of earth and sand water are arranged in the lower part 22 in the main body container 1 above the lower end of the first earth lifting pipe 2. The plurality of earth and sand mixing blade-like members 11 are arranged radially around the first earthpump 2. In the present embodiment, the earth and sand mixing blade-like member 11 is fixed to the cylindrical portion 23 of the first earth-pumping pipe 2 via a ring-like member 26. Moreover, the longitudinal direction of the earth and sand mixing blade-like member 11 is obliquely downward with respect to the cylindrical portion 23 of the first pumping pipe 2 so that the earth and sand water hits at an angle substantially perpendicular to the earth and sand mixing blade-like member 11. It is said that. The side surface of the umbrella part 24 of the first earthen pipe 2 and the earth and sand mixing blade-like member 11 are substantially parallel.

  As shown in FIG. 4B, the upper and lower ends of the earth / sand mixing blade-like member 11 in the main body container 1 as shown in FIG. Is also provided with a sharp edge 11a. In the present embodiment, a total of eight earth and sand mixing blade-like members 11 are attached to the periphery of the first earthing pipe 2, but the number is not limited to this. Moreover, although it is preferable to install the earth and sand mixing blade-shaped member 11 in the main body container 1, the installation of the earth and sand mixing blade-shaped member 11 is not essential.

(Inclined plate)
A plurality of inclined plates 12 are stacked on the upper portion of the main body container 1 with a predetermined interval in the vertical direction. The inclined plate 12 is for promoting gravity sedimentation of earth and sand except clay. In the present embodiment, the inclined plates 12 are arranged on both sides of the first uplift pipe 2 on the outer side in the upper radial direction so as to sandwich the first uplift pipe 2 therebetween. In addition, the inclined plate 12 is inclined in an obliquely downward direction from the inner wall of the main body portion 21 of the main body container 1 toward the inner side of the main body container 1 (toward the side surface of the first earthing pipe 2). In addition, the arrangement | positioning of the inclination board 12 and its inclination direction are not restricted to this.

(Separation and removal of cesium using contaminated soil treatment equipment)
Next, separation and removal of cesium using the contaminated soil treatment apparatus 100 will be described. Soil is composed of gravel, sand, clay and the like. Clay is a collection of fine particles formed by the decomposition of rocks by weathering or hydrothermal action, and is composed of various clay minerals and moisture. The main component of clay is a layered silicate mineral. Among them, kaolin mineral, mica clay mineral, mixed layer mineral and the like are typical clay minerals present in the clay as fine minerals. Layered silicate minerals are negatively charged and are structurally classified into 2: 1 layered layered silicate minerals and 1: 1 layered layered silicate minerals. It is known that both the 2: 1 layered silicate mineral and the 1: 1 layered silicate mineral adsorb cesium (hold and fix cesium firmly between layers).

  In soil science, secondary mineral particles having a weathering action with a particle size of 0.002 mm or less are referred to as clay, but in this application, secondary mineral particles having a weathering action with a particle size of 0.002 mm or less. It's not just clay. That is, as described above, clay as used in the present application is a collection of fine particles formed by decomposition of rocks by weathering or hydrothermal action, and is composed of various clay minerals and moisture.

(Contaminated soil input process)
First, contaminated soil in which cesium has accumulated (contaminated with cesium) is introduced into the contaminated soil treatment apparatus 100 (main body container 1) from the inlet 1b, and water is supplied from the water supply pipe 7 to the bottom of the main body container 1. (For example, tap water). At this time, for example, it is preferable that water is supplied into the main body container 1 prior to the introduction of the contaminated soil, and the water is stored to some extent at the bottom (lower part 22) of the main body container 1. The contaminated soil is dropped into the water collected to some extent at the bottom of the main body container 1. When the liquid level in the main body container 1 reaches a predetermined level, input of contaminated soil and water supply are stopped. For example, when the liquid level reaches a level at which all of the first pumping pipe 2 and the inclined plate 12 are submerged, the charging of the contaminated soil and the water supply are stopped. Of the gravel and sand contained in the contaminated soil put into the main body container 1, those having a relatively large particle size sink and accumulate on the bottom of the main body container 1. In addition, among the clay contained in the contaminated soil, most of the clay that is not attached to the gravel and sand and that is not agglomerated is in a state of floating in the liquid. Hereinafter, the mixture of contaminated soil and water will be referred to as earth and sand water.

(Air supply process)
Thereafter, the first air supply pipe 4 into the first earthing pipe 2, the second air supply pipe 5 into the second earthing pipe 3, and the third air supply pipe 6 into the discharge pipe 13 (the bottom of the main body container 1). ) To supply air. By supplying air from the first air supply pipe 4 into the first earthing pipe 2, earth and sand water is sucked in from the lower end opening of the first earthing pipe 2 by the air lift effect, and the inside of the first earthing pipe 2 together with the agitation promoting balls 14. To rise. Thereby, the contaminated soil in the earth and sand water is washed by stirring in the first earthing pipe 2 by the stirring promotion balls 14, air, and water. As a result, clay is peeled from the gravel and sand contained in the contaminated soil. Note that air from the second air supply pipe 5 and the third air supply pipe 6 also contributes to stirring and washing of the contaminated soil in the first earthing pipe 2.

  In addition, due to the air supply from the second air supply pipe 5 into the second pumping pipe 3, the earth and sand water is sucked in from the lower end opening of the second pumping pipe 3 by the air lift effect and rises in the second pumping pipe 3. Thereby, the contaminated soil in the earth and sand water is agitated and washed in the second pumping pipe 3 by air and water. As a result, clay is peeled from the gravel and sand contained in the contaminated soil. Here, the second earthing pipe 3 is located on the bottom side of the main body container 1 relative to the first earthing pipe 2, and the diameter of the second earthing pipe 3 is smaller than the diameter of the first earthing pipe 2. For this reason, the second earthen pipe 3 has a high ability to fry gravel and sand that have settled and accumulated on the bottom of the main body container 1. Therefore, gravel and sand (with a medium particle size) sinking and accumulating on the bottom of the main body container 1 can be caused to flutter in the second earthpump 3. When the gravel and sand dance in the second pumping pipe 3, the gravel and sand always collide with each other, and the cesium adhering to the surface of the gravel and sand is peeled off. The cesium peeled from the surface of the gravel / sand rises in the first earthing pipe 2, flows out from the discharge port 2a, and then slowly settles in the main body container 1 outside the first earthing pipe 2. Cesium is adsorbed by the clay in the process of slow sedimentation in the main body container 1 outside the first earthpump 2. As a result, the clay becomes a clay in which cesium is adsorbed at a high concentration.

  Here, among the gravel and sand that have been sunk and accumulated at the bottom of the main body container 1, those having a large particle diameter remain unsunk at the bottom of the main body container 1 without being fried by the second earth-pumping pipe 3. However, by supplying air from the third air supply pipe 6 to the inside of the discharge pipe 13 (bottom part in the main body container 1), the gravel / sand that remains in the bottom of the main body container 1 is swung at that position. It is done. As a result, the gravel and sand always collide with each other, and the cesium adhering to the surface of the gravel and sand is peeled off. The cesium peeled off from the surface of the gravel / sand rises in the second pumping pipe 3 and the first pumping pipe 2 and flows out from the discharge port 2a of the first pumping pipe 2, and then on the outside of the first pumping pipe 2 It sinks in the main body container 1 at a slow speed. Cesium is adsorbed by clay during the sedimentation process.

  Here, the amount of air flowing through the third air supply pipe 6 is preferably smaller than the amount of air flowing through the first air supply pipe 4 and the amount of air flowing through the second air supply pipe 5. In other words, the amount of air supplied to the bottom of the main body container 1 below the second earthen pipe 3 is less than the amount of air supplied to the first earthener pipe 2 and the amount of air supplied to the second earthend tube 3. It is preferable that This is because if the amount of air supplied from the third air supply pipe 6 to the inside of the discharge pipe 13 (the bottom portion in the main body container 1) is too large, the circulation flow in the main body container 1 is affected. The earth and sand water ascends in the second pumping pipe 3 and the first pumping pipe 2 and then overflows from the first pumping pipe 2 and sinks in the main body container 1. After that, it is sucked into the earthpipe and rises again in the earthpipe. This repeated circulation flow is the circulation flow in the main body container 1.

  In the lower part 22 in the main body container 1, a plurality of earth and sand mixing blade-like members 11 are arranged radially around the first earthing pipe 2. The downflow outside the first pumping pipe 2 is divided by these earth and sand mixing blade-like members 11. This promotes the separation of clay from gravel and sand. Since the plurality of earth and sand mixing blade-like members 11 are arranged radially around the first earth lifting pipe 2, the downward flow of earth and sand water can be divided over the entire circumference of the first earth raising pipe 2. Moreover, since the earth and sand mixing blade-like member 11 is attached to the first earthing pipe 2 so as to extend obliquely downward from the first earthing pipe 2, the earth and sand mixing blade-like member 11 is attached to the earth and sand mixing blade-like member 11. Sediment water hits at an almost vertical angle. As a result, the efficiency of dividing the downward flow is increased. And as shown in FIG.4 (b), the upper and lower ends of the earth-and-sand mixing blade-like member 11 are made into the acute-angled blade edge | tip part 11a. Thereby, the unloading efficiency by the air supply to the unloading pipes (2, 3) (by the air lift) is hardly affected by the presence of the earth-and-sand mixing blade-like member 11, and the dividing efficiency of the downward flow is further increased.

(Standing process (sediment separation process))
When the air supply from the air supply pipes (4, 5, 6) elapses for a predetermined time, the air supply is stopped and the earth and sand water in the main body container 1 is allowed to stand for a predetermined time. “Standing” refers to placing in a stationary state without stirring. When the earth and sand water is left standing, the gravel and sand contained in the earth and sand water sinks to the bottom of the main body container 1.

  Here, a plurality of inclined plates 12 are stacked on the upper portion of the main body container 1 with a predetermined interval in the vertical direction. The inclined plate 12 can increase the sedimentation speed of sand that is difficult to settle, and as a result, the time of the stationary step can be shortened. Sand deposited on the surface of the inclined plate 12 accumulates (concentrates) here, and then slides down the surface of the inclined plate 12. If the inclined plate 12 has a large surface area, the effect of sliding down is increased accordingly, and in this embodiment, a plurality of inclined plates 12 are stacked and arranged at predetermined intervals in the vertical direction.

  In addition, the effect by the above-mentioned inclination board 12 is exhibited also in an above-described air supply process. By increasing the sedimentation speed of the sand that hardly settles, circulation of the sand in the main body container 1 is promoted, and as a result, the stirring and washing efficiency of the sand that hardly settles increases. Here, in the air supply process described above, fine vibrations are generated in the first earthing pipe 2 by supplying air into the first earthing pipe 2. In the present embodiment, since the inclined plate 12 is inclined in a diagonally downward direction toward the side surface of the first earthing pipe 2 arranged in the vertical direction, the sand content sliding down the surface of the inclined plate 12 is: It contacts the surface of the first earthing pipe 2 that vibrates finely, and this also increases the sedimentation rate of sand.

  The air supply step and the stationary step (sediment separation step) described above are repeated as necessary. This enhances the separation of clay from gravel and sand, the separation of cesium from gravel and sand, and the adsorption of the separated cesium to clay.

(Drainage process)
Thereafter (after allowing the earth and sand water to stand for a predetermined time), the electric drain valve 14 is opened, and muddy water containing clay (clay-containing water) is drained from the drain pipe 8. Thereby, cesium is discharged | emitted in the state of muddy water with the clay in the state adsorbed by the clay. At this time, it is preferable that the drainage pipes 8a to 8e having different installation heights are sequentially drained from the drainage pipe located above. When sand (sand does not need to be disposed of) is contained in the muddy water drained from the drain pipe, the drainage is stopped according to the amount, and the air supply process and the stationary process (sediment separation process) described above Again. Whether the muddy water contains sand or not can be confirmed by attaching a visual window (not shown) to the drain pipes 8a to 8e, for example. Thereby, the amount of sand to be disposed of can be reduced, and a sufficient amount of sand (soil) used for backfilling can be secured.

  The discharged turbid water containing clay adsorbed with cesium is reduced in volume by subjecting the turbid water to drying treatment, coagulation sedimentation treatment, and the like.

(Processed soil discharge process)
When drainage from the drainage pipe located at the lowermost position among the drainage pipes 8a to 8e is completed, the electric discharge valve 15 is opened to extract (discharge) the treated soil from the discharge pipe 13. The extracted treated soil is transported by, for example, the container 51 and backfilled after confirming that the radiation dose is below a predetermined value. When the treated soil is slightly extracted from the discharge pipe 13 and the radiation dose exceeds a predetermined value, the air supply process, the stationary process (sediment separation process), and the drain process are performed again.

  In addition, what was described above is the batch operation (batch processing) of the contaminated soil treatment apparatus 100, but depending on the properties of the contaminated soil that is the decontamination target, the contaminated soil treatment apparatus 100 is operated continuously (continuous treatment). Also good. Continuous treatment refers to treatment in which the above-described stationary step (sediment separation step) is not particularly performed, and the above-described contaminated soil input step, air supply step, drainage step, and treated soil discharge step are performed in parallel. Say. In addition, the cesium can be separated together with the clay more reliably in the batch operation (batch process) involving the stationary process than in the continuous process. In the case of continuous treatment, all of the contaminated soil input into the main body container 1, water supply, air supply, drainage from the main body container 1 (drainage of clay-containing water), and discharge of the treated soil are all performed continuously. In some cases, some may be performed intermittently.

(Action / Effect)
According to the present invention, the constituent elements of the present invention, in particular, the upper and lower ends are both open and partly inserted into the lower end of the first earthing pipe 2 are arranged vertically at the bottom in the main body container 1. The gravel that has sunk and accumulated at the bottom of the main body container 1 by the second earthing pipe 3 having a smaller diameter than the first earthing pipe 2 and the second air supply pipe 5 that supplies air to the second earthing pipe 3. Sand (medium particle size) can be swept in the second pumping pipe 3. As a result, gravel and sand always collide with each other, and cesium (radioactive material) adhering to the surface of the gravel and sand can be efficiently peeled off (separation of cesium (radioactive material) from gravel and sand) it can). The clay attached to the gravel and sand can be removed sufficiently. Further, by supplying air from the third air supply pipe 6 to the bottom of the main body container 1 below the second earthmoving pipe 3, the gravel / sand that remains in the bottom of the main body container 1, It can be swung in position. Thereby, the state where the gravel and sand at the bottom of the main body container 1 always collide with each other can be created, and the cesium adhering to the surface of the gravel and sand at the bottom of the main body container 1 can be peeled off. The clay attached to the gravel and sand can be removed sufficiently. In addition, the merit which can perform a cesium (radioactive substance) removal process and a clay separation process in the immediate vicinity of the discharge | emission position of treated soil with respect to the gravel and sand which have settled and accumulated in the bottom of the main body container 1 is large.

  Moreover, in this invention, water is supplied to the bottom part in the main body container 1 below the second pumping pipe 3. If it does in this way, compared with supplying water from the upper part of main part container 1, the cleaning effect of the contaminated soil by water supply will increase. It is because the whole contaminated soil can be stirred from the bottom by supplying water to the bottom part in the main body container 1 below the second pumping pipe 3. Moreover, in the state where the contaminated soil is not put into the main body container 1, the cesium (radioactive substance) adhering to the bottom part (the drain pipe 13 in the above-described embodiment) in the main body container 1 can be peeled off by a direct jet. .

  In the present invention, the processes of separating clay from gravel and sand, separating cesium from gravel and sand, and adsorbing the separated cesium to clay are all performed in the main body container 1 closed from the outside. Therefore, the present invention is also excellent in safety.

  As described above, according to the present invention, radioactive substances (or heavy metals) can be efficiently and safely separated from soil contaminated with radioactive substances (or heavy metals).

(Another embodiment of the first earthen pipe)
FIG. 5 is a longitudinal sectional view showing another embodiment of the first earthen pipe 2 shown in FIG. In FIG. 5, the same reference numerals are given to the same components / members as shown in FIG. 1. Although not shown, a plurality of stirring promoting balls 14 are placed in the first earthing pipe 32 of the present embodiment, similarly to the first earthing pipe 2 shown in FIG.

  As shown in FIG. 5, the first earthen pipe 32 of the present embodiment has two cylindrical portions (34, 35) having different diameters. The cylindrical portion 34 extends vertically upward from the upper end of the cylindrical portion 35 and has a larger diameter than the cylindrical portion 35. Further, the enlarged diameter portion from the cylindrical portion 35 to the cylindrical portion 34 is tapered. The diameter expansion start position is an upper position than the connection position of the first air supply pipe 4. The cylindrical portion 35 and the cylindrical portion 34 are coaxial.

  A plurality of arc-shaped stirring promoting members 41 having a predetermined width are attached to the inner surface of the cylindrical portion 35. These stirring promoting members 41 are attached to the inner surface of the cylindrical portion 35 in a zigzag pattern in the vertical direction. The shape / arrangement of the stirring promoting member is not limited to that of the present embodiment.

  Here, in the embodiment shown in FIG. 1, since the diameter of the cylindrical portion 23 of the first earthmoving pipe 2 is the same from the upper end to the lower end, all of the inside of the cylindrical portion 23 is a “stir washing zone”. Yes. On the other hand, in the present embodiment, the cylindrical portion 35 becomes a “stirring cleaning zone”, and the cylindrical portion 34 above it becomes an “adsorption zone”. The rising speed of the earth and sand water decreases almost in proportion to the square of the diameter of the cylindrical portion. Therefore, by appropriately determining the diameter of the cylindrical portion 34 and the diameter of the cylindrical portion 35, the cylindrical portion of the first uplift pipe 32 is obtained. 33 can be divided into a “stir washing zone” having a high flow rate and an “adsorption zone” having a low flow rate.

  In the embodiment shown in FIG. 1, the inside of the main body container 1 outside the first earthpipe 2 is an “adsorption zone” in which cesium is mainly adsorbed by clay. As in this embodiment, by providing an “adsorption zone” in a part of the first pumping pipe 32, the adsorption efficiency of cesium to clay can be further increased.

  The earth and sand rising in the first pumping pipe 32 is agitated and washed in the cylindrical portion 35 by the agitation promoting ball 14, air, and water. At this time, earth and sand agitation and washing efficiency is improved by, for example, collision of earth and sand water with the agitation promoting member 41 attached to the inner surface of the cylindrical portion 35. In other words, by attaching the stirring promoting member 41 to the inner surface of the cylindrical portion 35, the efficiency of stirring and washing the earth and sand can be improved. Thereafter, cesium that has not been adsorbed by the clay is adsorbed by the clay in the process of the earth and sand water rising slowly in the cylindrical portion 34.

  In this embodiment, the agitation promoting ball 14 functions as a member that promotes washing of earth and sand water in the cylindrical portion 35 of the first earthing pipe 32, and promotes adsorption of cesium in the cylindrical part 34 of the first earthing pipe 32. It functions as a thing. The agitation promoting ball 14 rises in the cylindrical portion 34 while swinging irregularly, so that the earth and sand water that rises slowly together with air bubbles rising in the cylindrical portion 34 while swinging irregularly as well. Move complexly. Thereby, the contact frequency and contact time between cesium and clay are increased (longer), and the adsorption efficiency of cesium to clay is improved.

(Modified example of contaminated soil treatment equipment)
FIG. 6 is a longitudinal sectional view showing a modified example of the contaminated soil treatment apparatus 100 shown in FIG. In FIG. 6, the same components and members as those shown in FIG.

  As shown in FIG. 6, the contaminated soil treatment apparatus 101 of the present modification does not have the inclined plate 12 installed in the main body container 1. Thus, depending on the nature of the contaminated soil, the inclined plate 12 may not be installed. In the contaminated soil treatment apparatus 100 shown in FIG. 1, the inclined plate 12 may be removable, and the inclined plate 12 may be attached or removed in accordance with the properties of the contaminated soil.

  Although the embodiments of the present invention have been described above, the present invention is not limited to the above-described embodiments, and various modifications can be made as long as they are described in the claims. .

1: Main body container 2: First earthing pipe 3: Second earthing pipe 4: First air supply pipe 5: Second air supply pipe 6: Third air supply pipe 7: Water supply pipe 8: Drain pipe 9: Separation box 10 : Stirring promotion ball return pipe 14: Stirring promotion ball 100: Contaminated soil treatment device

Claims (11)

A contaminated soil treatment apparatus for separating radioactive materials or heavy metals from contaminated soil containing clay and containing radioactive materials or heavy metals,
The main body container into which the contaminated soil is charged and the treated soil is discharged from the bottom;
First upper and lower ends are both open, and are disposed vertically in the main body container;
A second smaller diameter than the first earthing pipe disposed vertically at the bottom in the main body container with both upper and lower ends being open and partly inserted into the lower end of the first earthing pipe. A deep-pipe pipe,
A first air supply pipe for supplying air to the first earthing pipe;
A second air supply pipe for supplying air to the second earthing pipe;
A third air supply pipe for supplying air to the bottom of the main body container below the second earthing pipe;
A water supply pipe for supplying water to a bottom portion in the main body container below the second pumping pipe;
A contaminated soil treatment apparatus, comprising: In the contaminated soil processing apparatus of Claim 1,
The contaminated soil treatment apparatus, wherein an amount of air flowing through the third air supply pipe is smaller than an amount of air flowing through the first air supply pipe and an amount of air flowing through the second air supply pipe. In the contaminated soil processing apparatus of Claim 1 or 2,
The contaminated soil treatment apparatus, wherein the first earthing pipe is enlarged in diameter at a portion above the connection position of the first air supply pipe, and an enlarged diameter part is provided in an upper part. In the contaminated soil processing apparatus in any one of Claims 1-3,
In the main body container above the lower end of the first earthen pipe, a plurality of earth and sand mixing blade-like members that divide the descending flow are arranged radially around the first earthen pipe, Contaminated soil treatment equipment. In the contaminated soil processing apparatus of Claim 4,
The contaminated soil treatment apparatus, wherein the earth-and-sand mixing blade-like member is attached so as to extend from the first earthing pipe in an obliquely downward direction with respect to the first earthing pipe. In the contaminated soil processing apparatus in any one of Claims 1-5,
A contaminated soil treatment apparatus, characterized in that an inclined plate is provided inside the main body container and on the outer side in the upper radial direction of the first earth-pumping pipe to promote sedimentation of earth and sand excluding clay. In the contaminated soil processing apparatus of Claim 6,
The contaminated soil treatment apparatus, wherein the inclined plate is inclined in an obliquely downward direction from an inner wall of the main body container toward a side surface of the first earthen pipe. The contaminated soil treatment apparatus according to claim 6 or 7,
A plurality of the inclined plates are arranged in a vertical direction with a predetermined interval, the contaminated soil treatment apparatus. A contaminated soil treatment method for separating radioactive substances or heavy metals from contaminated soil containing clay and containing radioactive substances or heavy metals,
While charging the contaminated soil into the main body container, the contaminated soil input step of supplying water to the bottom of the main body container,
The upper and lower ends are both open and air is supplied to a first earthing pipe arranged vertically in the main body container, and the upper and lower ends are both open and a part is inserted into the lower end of the first earthing pipe. In this state, air is supplied to the second earthed pipe having a diameter smaller than that of the first earthed pipe disposed vertically at the bottom of the main body container, and the body below the second earthed pipe An air supply process for supplying air to the bottom of the container;
A drainage step of draining muddy water containing clay from within the main body container;
A treated soil discharge step for discharging treated soil from the bottom in the main body container,
A method for treating contaminated soil, comprising: The contaminated soil treatment method according to claim 9,
Further comprising a stationary step of stopping the air supply in the air supply step and leaving the earth and sand water in the main body container for a predetermined time,
A method for treating contaminated soil, comprising performing each step in the order of the contaminated soil input step, the air supply step, the stationary step, the drainage step, and the treated soil discharge step. The contaminated soil treatment apparatus according to claim 9 or 10,
In the air supply step, the amount of air supplied to the bottom portion of the main body container below the second pumping pipe is greater than the amount of air supplied to the first pumping pipe and the amount of air supplied to the second pumping pipe. A method for treating contaminated soil, characterized in that it is also reduced.

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