JP2004130217A - Apparatus for treating contaminated soil - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To surely classify a contaminant together with the fine particle content of contaminated soil and to prevent the contaminant from intruding into the coarse particle content when the contaminated soil is classified and washed. <P>SOLUTION: This apparatus 1 for treating the contaminated soil is provided with a raw water tank 2, a vibratingly screening mechanism 3 which is arranged above the tank 2 and in which screens are arranged for sorting the soil particles by the prescribed size and a cyclone 4a as the first cyclone and another cyclone 4b as the second cyclone which are arranged above the mechanism 3 and connected communicatively to the tank 2 so that the muddy water of the tank 2 can be sent forcibly to the cyclones 4a and 4b. Screens 8, 9, 10, a muddy water receiving plate 11 and another screen 12 are arranged stepwise in this order from below in the mechanism 3. A water jetting mechanism is arranged above each of the screens 8, 9, 10, 12 for jetting water downward toward the earth and sand on the corresponding screen. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to an apparatus for treating contaminated soil used mainly for removing heavy metals contained in excavated soil.
[0002]
[Prior art]
When constructing a new building on the site of a factory, various contaminants such as cadmium, lead, copper, zinc, nickel, chromium, arsenic, and other pollutants such as volatile organochlorine compounds and oils are mixed into the excavated soil and carried out. May be done. If such contaminated soil is left as it is, the contaminants mixed in the soil may be mixed into groundwater or the like and diffused into the environment. Therefore, it is necessary to remove such contaminants by some method.
[0003]
As such a method, a technique is known in which excavated soil containing contaminants is once muddy, and then the muddy water is classified and washed (see Non-Patent Document 1).
[0004]
[Non-Patent Document 1] "Guidelines for Investigation and Countermeasures Regarding Soil and Groundwater Pollution and Operational Standards," Water Quality Conservation Bureau, Environment Agency, Soil Environment Center, published March 25, 1999
[0005]
[Problems to be solved by the invention]
The above classification and cleaning method classifies particles with a classification point of 75 μm, and for coarse particles (gravel, coarse sand, fine sand) of 75 μm or more, the treated soil from which contaminants have been removed, and fine particles of 75 μm or less. Minutes (silt, clay) are appropriately disposed of, for example, in the form of disposal, because they contain contaminants.
[0006]
In such a classification cleaning method, most contaminants are classified based on the idea that they will be classified together with fine particles having a particle size of 75 μm or less, but the applicant has performed the classification cleaning method in various situations. However, depending on the condition of the contaminated soil, many contaminants are mixed in the coarse particles of 75 μm or more, and the environmental standards cannot be cleared, and even the treated soil must be properly disposed of in the form of disposal. found.
[0007]
The present invention has been made in view of the above-described circumstances, and it is possible to reliably classify contaminants together with fine particles in classifying washing of contaminated soil and prevent contamination of the contaminants into coarse particles. It is an object of the present invention to provide an apparatus for treating contaminated soil.
[0008]
[Means for Solving the Problems]
In order to achieve the above object, a contaminated soil treatment apparatus according to the present invention is, as described in claim 1, a raw water tank and a sieve disposed above the raw water tank and for separating soil particles with a predetermined particle size. And a vibrating sieve mechanism provided with a vibrating sieve mechanism provided with a water jet mechanism for jetting water downward toward earth and sand on the sieve.
[0009]
Further, the apparatus for treating contaminated soil according to the present invention, as described in claim 2, has a raw water tank divided into a first section and a second section, and is disposed above the raw water tank and has a particle size. A vibrating sieve mechanism provided with at least two sieves for sorting soil particles in at least two stages according to the above, and muddy water in the first and second compartments of the raw water tank above the vibrating sieve mechanism is press-fitted. An apparatus for treating contaminated soil, comprising a first and a second cyclone, each of which is communicatively connected to the compartment, and comprising a water injection mechanism for injecting water downwardly toward the sediment on the sieve. Things.
[0010]
Further, the apparatus for treating contaminated soil according to the present invention includes an air injection mechanism that injects air downward toward earth and sand on the sieve at a discharge side of the sieve from a water injection position of the water injection mechanism. It is.
[0011]
Further, the apparatus for treating contaminated soil according to the present invention disposes a sediment agitating mechanism immediately above the sieve and on a side where the sieve is injected with respect to a water injection position of the water injection mechanism to break up the clod on the sieve. It is constructed so that it can be glued.
[0012]
Further, the apparatus for treating contaminated soil according to the present invention, on the upper surface of the sieve, a damming plate for damping the earth and sand transferred on the sieve on the input side of the sieve from the water injection position by the water injection mechanism. It was erected.
[0013]
Further, the apparatus for treating contaminated soil according to the present invention disposes a sediment agitating mechanism immediately above the sieve and on a side where the sieve is injected with respect to a water injection position of the water injection mechanism to break up the clod on the sieve. And an air injection mechanism for injecting air downward toward earth and sand on the sieve at a discharge side of the sieve from a water injection position of the water injection mechanism.
[0014]
Further, the apparatus for treating contaminated soil according to the present invention, on the upper surface of the sieve, a damming plate for damping the earth and sand transferred on the sieve on the input side of the sieve from the water injection position by the water injection mechanism. An air injection mechanism is provided which stands up and injects air downwardly toward earth and sand on the sieve on the discharge side of the sieve from the water injection position of the water injection mechanism.
[0015]
Further, the apparatus for treating contaminated soil according to the present invention, on the upper surface of the sieve, a damming plate for damping the earth and sand transferred on the sieve on the input side of the sieve from the water injection position by the water injection mechanism. In addition to being erected, a sediment stirring mechanism is installed just above the sieve and between the dam plate and the water injection position so that the earth mass on the sieve can be peptized.
[0016]
The present applicant considers that as a cause of a large amount of contaminants being mixed into coarse particles (gravel, coarse sand, fine sand) of 75 μm or more, first, the clay mass containing the contaminants Secondly, the water content of the sand on the sieve is reduced due to vibration by the vibrating sieve mechanism, and the contaminants are discharged in a state where the contaminants are trapped in the sediment. Thirdly, the inventor has found that the water containing pollutants is discharged together with the sediment and sediment without sufficiently draining the water on the sieve. is there.
[0017]
That is, the apparatus for treating contaminated soil according to the present invention is provided with a water injection mechanism for injecting water downward toward the sediment on the sieve, and directing the sediment sorted on the sieve from the water injection mechanism. And spray water downward.
[0018]
In this way, if there is earth mass, particularly earth mass in the form of a clay mass, the earth mass is first crushed by the force of the injected water, and then the earth mass is contained in the earth mass of the earth mass. The contaminated material is blown off by the force of the injected water, passes through a sieve, and falls into a raw water tank. In addition, the contaminants and surface water containing the contaminants attached to the surface of the soil particles in the crushed soil mass are also blown off by the force of the jetted water, pass through the sieve, and pass through the raw water tank. To fall.
[0019]
On the other hand, even when there is no earth mass, the contaminants and surface water containing the contaminants that have adhered to the surface of the soil particles in the sediment are blown off by the force of the injected water, pass through the sieve, and enter the raw water tank. Fall.
[0020]
Therefore, by collecting the sediment remaining on the sieve, it becomes possible to separate only the sediment containing little contaminant from the contaminated soil as treated soil.
[0021]
On the other hand, muddy water in a raw water tank containing a large amount of contaminants is appropriately dewatered using a cyclone, a screw decanter, a filter press, or the like, and the dewatered cake is appropriately disposed of in a form such as disposal, and dewatered. The treated water is subjected to a treatment for removing contaminants, a pH adjustment and other necessary treatments, and then appropriately discharged to a river or the like.
[0022]
Here, in the apparatus for treating contaminated soil according to claim 2, first, drilling mud is put on a sieve capable of mainly sorting gravels out of coarse particles, and then the same as described above on the sieve After the washing by the water jetting mechanism, the selected gravel is discharged to be treated soil, and the muddy water that has passed through the sieve is dropped into the first section of the raw water tank. In addition, even if there is an earthen mass in the muddy water, the earthen mass is crushed by the force of the injection water as described above, and thus there is no possibility that the earthen mass is sorted by the sieve and discharged together with the gravel.
[0023]
Next, the muddy water stored in the first section is pressed into the first cyclone to classify, for example, 75 μm as a classification point, and the cyclone under muddy is mainly sorted into coarse sand and fine sand among coarse particles. After being put on a possible sieve, and then washed by a water injection mechanism on the sieve in the same manner as described above, the selected coarse sand and fine sand are discharged into a treated soil while discharging. By repeatedly performing the procedure of dropping the muddy water that has passed through the sieve into the first section of the raw water tank, as much coarse sand and fine sand as possible can be sorted and collected without pollutants. Incidentally, even when the earth mass is generated by the vibration action on the sieve, the earth mass is crushed by the force of the jet water as described above, so that the earth mass is sorted by the sieve and discharged together with the coarse sand and the fine sand. There is no danger.
[0024]
Here, in the first cyclone, the contaminant comes over as a cyclone over mud with fine particles (silt, clay) smaller than 75 μm, but on the other hand, it sufficiently prevents the contaminant from being mixed into the under mud. It is difficult.
[0025]
Therefore, with respect to the cyclone under mud, contaminants are removed by the above-mentioned water washing together with sorting and collecting coarse sand and fine sand.
[0026]
On the other hand, muddy water over the first cyclone contains many contaminants as described above, but on the other hand, it is difficult to sufficiently classify soil particles larger than 75 μm, especially fine sand. Mix into the over mud. The accumulated amount during the circulation cleaning / circulation sorting of the mud in the first section described above is an amount that cannot be ignored.
[0027]
Therefore, the muddy water that has exceeded the first cyclone is stored in the second section of the raw water tank, and then the muddy water stored in this section is injected into the second cyclone, for example, with a classification point of 75 μm as a classification point. I do.
[0028]
Here, as for the cyclone under mud of the second cyclone, fine sand is classified and contaminants are mixed. Therefore, this is put on a sieve capable of sorting coarse sand and fine sand described above. Then, after washing by a water injection mechanism on the sieve in the same manner as described above, the selected fine sand is discharged to be treated soil, and the muddy water that has passed through the sieve is discharged to the first water tank of the raw water tank. Drop it on the compartment. After that, as described above, the fine sand mixed into the mud in the second compartment is removed in a form containing no contaminants by performing the circulating washing and sorting on the mud in the first compartment as described above. Selectively collect.
[0029]
On the other hand, in the cyclone over mud of the second cyclone, most of the coarse particles (gravel, coarse sand, fine sand) of 75 μm or more are separated and removed, and the contaminants are contained in a concentrated state. .
[0030]
Therefore, the mud that has passed over the second cyclone is discharged to the outside, and is appropriately dewatered using a screw decanter, a filter press, or the like, and the dehydrated cake is appropriately disposed of in a form such as disposal. The dehydrated water is subjected to a treatment for removing contaminants, pH adjustment and other necessary treatments, and then discharged to a river or the like as appropriate.
[0031]
The vibrating sieve mechanism may have any configuration as long as a sieve is provided so as to select soil particles having a predetermined particle size by vibrating action. It is general that the excavated sediment is passed through the sieves in order from the one with the largest opening, and the sediment with the larger particle size is generally selected in order. However, the number of sieves is arbitrary.
[0032]
It is desirable that the water jetting mechanism be configured so that high-pressure water can be jetted as far as possible without causing any trouble in sorting the soil and the sieve.
[0033]
The jetting direction of the water jetting mechanism needs to be downward, but the term “downward” as used in the present specification is not limited to the vertical downward direction. It is conceivable that the cleaning efficiency can be improved by doing so.
[0034]
Regarding the earth and sand from which the contaminants have been blown off by the water jetted from the water jetting mechanism, the soil may be collected as it is as treated soil, but it may be collected on the sieve at the discharge side of the sieve from the water jetting position by the water jetting mechanism. In the case where an air injection mechanism that injects air downward toward the earth and sand is provided, it becomes possible to remove water from the earth and sand from which water has been injected by the water injection mechanism, thereby reducing the water content of the treated soil in advance. In addition to this, contaminants slightly adhering to the coarse particles due to the presence of water can be reliably dropped below the sieve.
[0035]
It is desirable that the air injection mechanism be configured so as to inject high-pressure air as much as possible within a range that does not hinder the selection of earth and sand and does not damage the sieve.
[0036]
The injection direction of the air injection mechanism needs to be downward, but the downward direction in this specification is not limited to the vertical downward direction as in the case of the water injection mechanism. It is conceivable to increase the moisture removal efficiency by injecting diagonally downward.
[0037]
As described above, the soil content of the sieve on the sieve decreases due to the vibration action, and tends to be in the form of earth mass. Therefore, if it is configured immediately above the sieve and a sediment agitating mechanism is installed on the input side of the sieve from the water injection position of the water injection mechanism so that the earth mass on the sieve can be peptized, By driving the stirring mechanism, the soil mass on the sieve is peptized in advance, and the subsequent step of washing with water can be performed more reliably.
[0038]
On the other hand, the transfer speed of the sediment on the sieve is set to be large to some extent from the viewpoint of the overall efficiency of sediment separation, and although the water content decreases due to the vibrating action, without sufficient draining, the coarse particles are not removed. Often they are emitted.
[0039]
In such a case, a blocking plate for blocking the earth and sand transferred on the sieve on the input side of the sieve from the water injection position by the water injection mechanism is provided upright on the upper surface of the sieve. Once the transferred earth and sand is once blocked by the blocking plate, sufficient drainage can be performed. By the way, since the transferred sediment is constantly being sent in from the input side, the sediment that has been dammed, combined with the vibrating action, passes over the damming plate in order from the one that has been sufficiently drained, and then is washed with water. Will be done.
[0040]
In addition, the above-mentioned earth and sand stirring mechanism, the air injection mechanism, and the dam plate can be used in an appropriate combination.
[0041]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, an embodiment of an apparatus for treating contaminated soil according to the present invention will be described with reference to the accompanying drawings. In addition, the same reference numerals are given to components and the like that are substantially the same as those in the related art, and description thereof is omitted.
[0042]
FIG. 1 is a schematic diagram showing a treatment apparatus for contaminated soil according to the present embodiment. As can be seen from the figure, the apparatus 1 for treating contaminated soil according to the present embodiment includes a raw water tank 2 and a vibration provided with a sieve that is disposed above the raw water tank and that sorts soil particles of a predetermined particle size. A sieve mechanism 3, a cyclone 4a as a first cyclone and a cyclone 4b as a second cyclone, which is connected above the vibrating sieve mechanism so that muddy water in the raw water tank 2 can be press-fitted therein.
[0043]
The raw water tank 2 is internally divided into a section 5a as a first section and a section 5b as a second section, and the section 5a is connected to a slurry pump 6a in communication with the section 5a. By connecting to the cyclone 4a, the muddy water in the section 5a can be pressed into the cyclone 4a.
[0044]
Similarly, a slurry pump 6b is connected in communication with the section 5b, and by connecting the pump to the cyclone 4b, muddy water in the section 5b can be pressed into the cyclone 4b.
[0045]
The vibrating sieve mechanism 3 is configured such that a screen as a sieve is installed in a five-bed system inside a box-shaped frame body 7 on which a vibrator (not shown) is installed. That is, in the frame 7, a screen 8, a screen 9, a screen 10, a mud receiving plate 11 and a screen 12 are installed in a stepwise order from the bottom. There is provided a charging chute 13 for charging. The screens 8 and 9 sort the gravels, which are mainly coarse particles, while transferring the earth and sand in the excavated mud fed through the input chute 13 to the discharge side on the right side in FIG. The openings are set so that they can be drained by the.
[0046]
Similarly, the screens 10 and 12 sort coarse sand and fine sand, which are coarse particles, while transferring the earth and sand in the cyclone under mud from the cyclones 4a and 4b to the discharge side, and discharge the sand at the ends. Are set to those apertures. The muddy water receiving plate 11 is made of, for example, an iron plate, and the under muddy water of the cyclone 4a that has passed through the screen 12 is dropped directly on the raw water tank 2 without falling onto the screen 10 below the cyclone 4a. It is designed not to increase the ratio.
[0047]
FIG. 2 is a detailed view of the screens 8 and 9. As can be seen from the figure, the apparatus 1 for treating contaminated soil according to the present embodiment includes a water jetting mechanism 22 for jetting water downward toward the soil 21 and 21a on the screens 8 and 9. The water injection mechanism includes injection nozzles 23 that inject water to the screens 8 and 9 and a high-pressure water pump 25 that supplies high-pressure water to the injection nozzles.
[0048]
In addition, the apparatus 1 for treating contaminated soil according to the present embodiment has an air jet that injects air downward toward earth and sand on the screen on the discharge side of the screens 8 and 9 from the water injection position of the water injection mechanism 22. The air injection mechanism includes a mechanism 26, and includes injection nozzles 27, 27 for injecting air to the screens 8, 9, and an air compressor 28 for high-pressure air injection for forcing high-pressure air to the injection nozzles.
[0049]
In addition, immediately above the screens 8 and 9 and closer to the input side of the screen than the water injection position of the water injection mechanism 22, the earth and sand agitating mechanism 29, 29, the earth and sand stirring mechanism is provided with a stirring blade 31 protruding radially from a rotating rod, and the rotating rod is moved in a direction opposite to the direction in which the earth and sand 21 and 21a are transported. The screens 8 and 9 can be crushed and deflocculated by rotating them around the horizontal axis.
[0050]
Further, on the input side of the screens 8 and 9 relative to the water injection position of the water injection mechanism 22, damming plates 32 and 32 for damping the earth and sand 21 transferred on the screens stand on the upper surfaces of the screens 8 and 9, respectively. It is set up.
[0051]
FIG. 3 is a detailed view of the screens 12 and 10. As can be seen from the figure, the water jetting mechanism 22 can jet water downward also to the earth and sand 41, 43 on the screens 12, 10 via the jetting nozzles 23, 23.
[0052]
Further, the air injection mechanism 26 can inject air downward through the injection nozzles 27 and 27 to the earth and sand 41 and 43 on the screen on the discharge side of the screens 12 and 10 from the water injection position of the water injection mechanism 22. It has become.
[0053]
To separate and remove contaminants, for example, heavy metals such as cadmium, lead, copper, zinc, nickel, chromium, and arsenic from contaminated soil using the contaminated soil treatment apparatus 1 according to the present embodiment, first, excavate the contaminated soil. Then, the excavated earth and sand is muddy to make excavated mud.
[0054]
In addition, when excavated muddy water is generated in a muddy water method such as an underground continuous wall method and a muddy water shield method, and heavy metal is mixed in the excavated muddy water, the muddy water is formed from the beginning. Can be omitted.
[0055]
Next, the excavated muddy water is dropped onto the screens 8 and 9 via the input chute 13, and large gravels and concrete garbage which are coarse particles on the screen 9 having the largest aperture of, for example, 40 mm. Is removed.
[0056]
Here, in the sorting and removing, first, the earth and sand 21 transferred on the screen 9 is once blocked by the blocking plate 32.
[0057]
By doing so, the soil 21 is subjected to the vibrating action of the vibrating sieve mechanism 3 in a state where it is blocked, so that sufficient drainage can be performed. By the way, since the earth and sand 21 are continuously fed from the input side, the earth and sand 21 which has been dammed passes over the damming plate 32 in order from the one after the sufficient drainage is completed, in combination with the vibration action.
[0058]
Next, the clay lumps originally contained in the drilling mud and the clay lumps newly generated by the dehydration due to the vibration on the screen 9 are pulverized into pieces by the stirring blades 31 of the earth and sand stirring mechanism 29.
[0059]
Next, high-pressure water is injected from the injection nozzle 23 of the water injection mechanism 22 toward the earth and sand 21 on the screen 9, and the injection direction is obliquely downward so as to oppose the transfer direction of the earth and sand 21 in order to increase the cleaning efficiency. Set to.
[0060]
In this way, when the soil mass, especially the clay mass, which has not been peptized by the earth and sand stirring mechanism 29 is present in the earth and sand 21, the mass of the earth mass is first crushed by the force of the injection water, and then the mass of the earth mass is The heavy metal contained therein is blown off by the force of the jet water, passes through the screens 8 and 9, and falls into the raw water tank 2. In addition, of the crushed sediment derived from the lumps, heavy metal and surface water containing the heavy metal, which have adhered to the surface of coarse particles such as gravel and concrete gala, are similarly blown off by the force of the jet water, and the screen 8, 9 and falls into the raw water tank 2.
[0061]
On the other hand, even when there is no earth mass, the heavy metal and the surface water containing the heavy metal that have adhered to the surface of the earth particles in the earth and sand 21 are blown off by the force of the jet water together with the coarse particles and the fine particles that are not sorted by the screen 9. Then, it falls through the screens 8 and 9 into the raw water tank 2.
[0062]
In such a state, for example, only the gravels 33 remain on the screen 9.
[0063]
Next, the air injection mechanism 26 is operated to inject high-pressure air from the injection nozzle 27 toward the gravel 33 on the screen 9, and in order to increase the efficiency of removing moisture, the injection direction is opposed to the transfer direction of the gravel 33. The angle is set obliquely downward, for example, about 30 ° rearward.
[0064]
High-pressure air is, for example, 2 to 4 kg / cm ² It is desirable to spray in a curtain shape.
[0065]
In this way, it is possible to remove water from the gravel 33 from which air has been injected by the air injection mechanism 26, and it is possible to reduce the water content of the treated soil in advance, and to slightly reduce the gravel due to the presence of water. The heavy metal adhering to 33 can be reliably dropped below the screen 9.
[0066]
As described above, a series of operations such as charging of excavated muddy water, draining by the dam plate 32, pulverization of clay lumps by the earth and sand stirring mechanism 29, blowing of heavy metals by the water injection mechanism 22, and blowing of moisture by the air injection mechanism 26 are screened. If it is performed on 9, the gravel 33 which does not contain heavy metals and has a small water content is finally sorted on the screen, and is collected as treated soil.
[0067]
Next, the earth and sand 21a that has passed through the sieve of the screen 9 is treated in the same manner as described above. That is, since there is a concern that the gravels 33a having a small particle size remain in the earth and sand 21a and that the clay lumps 30 are newly formed on the screen 8, the draining by the damming plate 32 and the clay lumps by the earth and sand stirring mechanism 29 are performed. A series of operations are performed on the screen 8, such as peptization of water, blowing of heavy metal by the water jetting mechanism 22, and blowing of moisture by the air jetting mechanism 26.
[0068]
In this manner, similarly to the sorting operation on the screen 9, the gravel 33a that does not contain heavy metals and has a small water content is finally sorted on the screen, and is collected as treated soil.
[0069]
Next, the muddy water that has passed through the screens 9 and 8 sequentially falls into the first section 5a of the raw water tank 2 and is stored therein. Therefore, the muddy water is pressed into the cyclone 4a by the slurry pump 6a. Classify as
[0070]
In this manner, soil particles having a particle diameter of 75 μm or more, that is, cyclone under muddy water containing coarse sand and fine sand as coarse particles are dropped on the screen 12.
[0071]
Here, as shown in FIG. 3, the screen 12 is provided with openings so that sand, particularly coarse sand, can be sorted out, and is configured to have an upward slope toward the discharge side to facilitate dehydration. In addition, it is configured in a step shape to reduce the overall height.
[0072]
Then, when the cyclone under mud is injected from the cyclone 4a, first, a large amount of the water passes through the screen 12 and falls to the muddy water receiving plate 11, which is returned to the first section 5a of the raw water tank 2. It is.
[0073]
Next, while the sediment 41 remaining on the screen 12 is transferred from the input side to the discharge side (right direction in the figure) on the screen, coarse particles corresponding to the openings are sorted out. Fine sand having a small diameter or water subjected to vibration dehydration passes through the screen 12 and falls onto the lower screen 10.
[0074]
During the sorting, the heavy metal is blown off by the water injection mechanism 22 and the water is blown off by the air injection mechanism 26 on the screen 12, so that coarse sand containing no heavy metal and having a small water content is mainly used. The coarse particles 42 are sorted on the screen, and are collected as treated soil.
[0075]
Like the screen 12, the screen 10 is provided with openings so as to be able to sort out sand, particularly fine sand, as shown in FIG. 3, and is easily dehydrated by having an upward slope toward the discharge side. The screen 10 is configured in a stepwise manner to reduce the overall height, and fine sand passing through the screen 12 and cyclone under mud from the cyclone 4b are introduced. Above, while the earth and sand 43 are being transferred from the input side to the discharge side (rightward in the figure) on the screen, coarse particles corresponding to the openings are sorted out, and fine particles or water having a smaller particle size are removed. , Passes through the screen 10 and falls into the section 5a of the raw water tank 2.
[0076]
In addition, even during such sorting, by blowing off heavy metals by the water injection mechanism 22 and blowing off moisture by the air injection mechanism 26 on the screen 10, fine sand containing no heavy metal and having a small water content is mainly used. The coarse particles 44 are sorted on the screen, and are collected as treated soil.
[0077]
In this way, the muddy water in the section 5a of the raw water tank 2 is pressed into the cyclone 4a, and the cyclone under muddy water is washed with the screens 12 and 10 to sequentially sort and collect coarse and fine sand. By repeating the procedure of dropping the muddy water passing through the screen into the section 5a of the raw water tank 2, as much coarse sand and fine sand as possible are surely sorted and collected without containing heavy metals. In addition, even when the earth mass is generated by the vibrating action on each of the screens 12 and 10, the earth mass is crushed by the force of the jetting water as described above. There is no risk of being discharged with fine sand.
[0078]
On the other hand, after being injected into the cyclone 4a by the slurry pump 6a, the over mud over the cyclone contains a large amount of heavy metals together with fine particles (silt, clay) smaller than 75 μm. It is stored in the section 5b of the raw water tank 2.
[0079]
However, at the time of classification in the cyclone 4a, not all heavy metals can be recovered as over muddy water, and it is difficult to avoid mixing with under muddy water. At the time of recovery, as described above, heavy metals are removed by washing with water.
[0080]
Next, the mud stored in the section 5b is over mud of the cyclone 4a, but coarse particles of 75 μm or more, especially fine sand, cannot be sufficiently classified by the cyclone. It is also mixed in.
[0081]
Therefore, the muddy water stored in the section 5b is pressed into the cyclone 4b by the slurry pump 6b, and the classification is performed again using, for example, 75 μm as a classification point. Then, the under muddy water is put into the screen 10 as already described with reference to FIG. 3, and while the fine sand is mainly sorted on the screen, the heavy metal is removed by the water injection mechanism 22 and the air is injected by the air injection mechanism 26. Moisture is removed and, finally, fine sand containing no heavy metal and having a small water content is collected as treated soil, while muddy water that has passed through the screen is dropped into the first section 5a of the raw water tank. After that, as described above, the fine sand mixed with the mud in the second section 5b is free from heavy metals by performing the circulating washing and circulating sorting on the mud in the first section 5a. Sort and collect with certainty.
[0082]
Next, in the cyclone over mud of the cyclone 4b, most of coarse particles (gravels, coarse sand, fine sand) of 75 μm or more are separated and removed, and heavy metals are contained in a concentrated state.
[0083]
Therefore, the mud that has passed over the cyclone 4b is discharged to the outside, and is appropriately dewatered using a screw decanter, a filter press, or the like, and the dehydrated cake is appropriately disposed of in a form of disposal or the like. The treated water is subjected to a treatment for removing heavy metals, a pH adjustment and other necessary treatments, and then appropriately discharged to a river or the like.
[0084]
As described above, according to the apparatus 1 for treating contaminated soil according to the present embodiment, water is jetted from the water jetting mechanism 22 toward the soil on each of the screens 9, 8, 12, and 10. When there is soil, particularly clay in the form of a clay mass, the mass of the injected water first crushes the mass, and then the contamination of heavy metals and the like contained in the mass of soil. The substance is blown off by the force of the jetted water, passes through the screens 9, 8, 12, and 10, and falls into the raw water tank 2. In addition, the contaminants and surface water containing the contaminants attached to the surface of the soil particles in the crushed soil mass are also blown off by the force of the jetted water, pass through the sieve, and pass through the raw water tank. To fall. On the other hand, even when there is no earth mass, the contaminants adhering to the surface of the soil particles in the soil and the surface water containing the contaminants are blown off by the force of the jetted water, and each of the screens 9, 8, 12, 10 and falls into the raw water tank 2.
[0085]
As a result, it is possible to separate only contaminated soil containing little contaminants from the contaminated soil as treated soil, and thus, in the past, dispose in the form of disposal due to the contamination of heavy metals and other contaminants. According to the present invention, it is necessary to recycle such treated soil into backfill soil, embankment, landfill soil, and the like.
[0086]
Further, according to the treatment apparatus 1 for contaminated soil according to the present embodiment, it is possible to remove water from the earth and sand from which water is injected by the water injection mechanism 22 by the air injection mechanism 26, and to reduce the water content of the treated soil. It can be lowered in advance, and the contaminants slightly adhering to the coarse particles due to the presence of water can be surely dropped below the screens 9, 8, 12, and 10.
[0087]
Further, according to the contaminated soil treatment apparatus 1 according to the present embodiment, the soil mass on the screens 9 and 8 is deflocculated in advance by driving the earth and sand stirring mechanism 29, and the subsequent step of washing with water is more reliably performed. be able to.
[0088]
Further, according to the apparatus 1 for treating contaminated soil according to the present embodiment, the dam plate 32 for damping the earth and sand transferred on the screens 9 and 8 is provided upright on the upper surface of the screen. The transferred earth and sand is once blocked by the blocking plate 32, and sufficient drainage can be performed.
[0089]
In this embodiment, the screens 9 and 8 are provided with a dam plate 32, a sediment stirring mechanism 29, a water injection mechanism 22, and an air injection mechanism 26, and the screens 12 and 10 are provided with the water injection mechanism 22 and the air injection mechanism 26. However, the number of stages of the screen is arbitrary, and as long as the water jetting mechanism 22 is installed on any one of the screens, the damming plate 32 and the earth and sand stirring are provided on the other screens. The combination of the mechanism 29, the water injection mechanism 22, and the air injection mechanism 26, which is not installed, is a design item that can be arbitrarily set according to the state of the drilling mud.
[0090]
For example, regarding the screens 9 and 8, if sufficient draining can be performed due to the transport speed of the earth and sand and the installation angle of the screen, the damming plate 32 can be omitted, and the lumps can be dismantled. If only the water jetting mechanism 22 is sufficient for stiffening, there is no need to install the earth and sand stirring mechanism 29. Further, the air injection mechanism 26 may be omitted as long as the soil and sand injected by the water injection mechanism 22 can be sufficiently drained by the subsequent draining action on the screen.
[0091]
If the screens 12 and 10 cannot be sufficiently drained due to the transport speed of the earth and sand and the installation angle of the screens, the damming plate 32 should be erected similarly to the screens 9 and 8. Alternatively, if the water jetting mechanism 22 alone is not enough to pulverize the earth mass and preliminary pulverization is required, the earth and sand stirring mechanism 29 may be installed in the same manner as the screens 9 and 8.
[0092]
In the present embodiment, the raw water tank 2 is divided into two sections 5a and 5b and two cyclones 4a and 4b are provided. However, the raw water tank is made one section and the cyclone is omitted. Is also good.
[0093]
FIG. 4 shows an apparatus 51 for treating contaminated soil showing such a modification.
[0094]
The apparatus 51 for treating contaminated soil shown in the figure includes a raw water tank 52, and a vibrating sieve mechanism 3 provided above the raw water tank and provided with a sieve for sorting soil particles with a predetermined particle size. A slurry pump 56 is connected to the raw water tank 52 so that muddy water in the raw water tank 52 can be supplied from above the vibrating sieve mechanism 3. The configuration of the water jetting mechanism 22, the air jetting mechanism 26, the dam plate 32, and the sediment stirring mechanism 29 and the operation and effect thereof are the same as those in the above-described embodiment, and thus the description thereof is omitted here.
[0095]
This configuration is also substantially the same as the embodiment except for the cyclone, and the muddy water stored in the raw water tank 52 is pumped up by the slurry pump 56 and passed through the screens 9, 8, 12, and 10, The sediment was sorted out while draining by the damming plate 32, peptizing the clay lump by the earth and sand stirring mechanism 29, washing the contaminant with the water jetting mechanism 22, and removing water by the air jetting mechanism 26, and passed through the screen. The muddy water is returned to the raw water tank 52, and a series of operations of passing the muddy water through the screens 9, 8, 12, and 10 again is repeated, so that sediment almost free of pollutants can be collected as treated soil. It is possible.
[0096]
Since a large amount of contaminants will eventually be contained in the muddy water in the raw water tank 52, the contaminants may be pumped up by the slurry pump 57 and sent to a water treatment device (not shown) to perform appropriate water treatment.
[0097]
Also in this configuration, various combinations can be considered for the combination of the dam plate 32, the earth and sand stirring mechanism 29, and the air injection mechanism 26, as in the above-described embodiment.
[0098]
【The invention's effect】
As described above, according to the apparatus for treating contaminated soil according to the present invention, water is sprayed from the water spray mechanism toward the sediment on the sieve, so that the water adheres to the surface of the soil particles in the soil. The contaminants and surface water containing the contaminants are blown away by the force of the injected water. Therefore, in the classification and washing of the contaminated soil, the contaminant can be surely classified together with the fine particles, and the contamination of the contaminant into the coarse particles can be prevented.
[0099]
[Brief description of the drawings]
FIG. 1 is a schematic diagram of an apparatus for treating contaminated soil according to the present embodiment.
FIG. 2 is a detailed sectional view of screens 9 and 8;
FIG. 3 is a detailed sectional view of screens 12 and 10.
FIG. 4 is a schematic diagram of an apparatus for treating contaminated soil according to a modification.
[Explanation of symbols]
1,51 Contaminated soil treatment equipment
2,52 Raw water tank
3 Vibrating sieve mechanism
4a First cyclone
4b Second cyclone
5a First section
5b Second section
8,9,10,12 Screen (Sieve)
22 Water injection mechanism
26 Air injection mechanism
29 Sediment stirring mechanism
32 dam plate

Claims (8)

A raw water tank, and a contaminated soil treatment device provided with a vibrating sieve mechanism provided with a sieve disposed above the raw water tank and sorting soil particles with a predetermined particle size, wherein the sediment on the sieve An apparatus for treating contaminated soil, comprising a water injection mechanism for injecting water downward. A raw water tank divided inside into a first section and a second section, and at least two sieves arranged above the raw water tank and sorting soil particles in at least two stages according to the particle size are provided. A vibrating sieve mechanism, and first and second cyclones above the vibrating sieve mechanism and connected to the first and second compartments of the raw water tank, respectively, so that the muddy water can be press-fitted therein. An apparatus for treating contaminated soil, comprising: a water injection mechanism for injecting water downward toward earth and sand on the sieve. The apparatus for treating contaminated soil according to claim 1 or 2, further comprising an air injection mechanism for injecting air downward toward earth and sand on the sieve at a discharge side of the sieve from a water injection position by the water injection mechanism. . 3. The structure as claimed in claim 1, wherein a sediment stirring mechanism is installed immediately above the sieve and on a side of the sieve where water is injected by the water injection mechanism to pulverize the earth mass on the sieve. An apparatus for treating contaminated soil as described in the above. The pollution according to claim 1 or 2, wherein a damming plate for damping earth and sand transferred on the sieve on a side of the sieve that is input from the water jetting position by the water jetting mechanism is provided upright on the upper surface of the sieve. Soil treatment equipment. Immediately above the sieve, a soil stirring mechanism is installed on the input side of the sieve from the water injection position of the water injection mechanism so as to be able to pulverize the earth mass on the sieve, and the water injection mechanism The treatment apparatus for contaminated soil according to claim 1 or 2, further comprising an air injection mechanism for injecting air downward toward earth and sand on the sieve at a discharge side of the sieve from a water injection position. An erecting plate is provided on the upper surface of the sieve for damping earth and sand transferred on the sieve on the input side of the sieve more than the water injection position of the water injection mechanism, and a water injection position of the water injection mechanism is provided. 3. The treatment apparatus for contaminated soil according to claim 1, further comprising an air injection mechanism that injects air downward toward earth and sand on the sieve at a discharge side of the sieve. An erecting plate is provided on the upper surface of the sieve for damming earth and sand transferred on the sieve on the input side of the sieve from the water injection position by the water injection mechanism, and the sieve is located immediately above the sieve. 3. The apparatus for treating contaminated soil according to claim 1, wherein a soil churning mechanism is provided between the dam plate and the water injection position so that the soil mass on the sieve can be peptized. 4.

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