JP2002307047A - Soil cleaning method and soil cleaning apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a soil cleaning method capable of efficiently cleaning polluted soil positioned under an unpolluted soil layer, and a soil cleaning apparatus used therein. SOLUTION: The soil cleaning method consists of a process for forming an excavated hole 4 having depth allowing the nozzle provided to the rotary shaft 22c, which constitutes the excavation part of the soil cleaning apparatus 20, to reach polluted soil by rotating the rotary shafts 22c, a process for excavating the polluted soil by ejecting water and air from the nozzle while rotating the rotary shaft 22c under high pressure to form a space 5, a process for discharging the polluted soil as cut earth and sand 1c along with an extraction solution through the excavated hole 4, a process for extracting a pollutant contained in cut earth and sand 1e, a solid-liquid separation process for separating the cut earth and sand 1c after extraction treatment into a liquid containing the pollutant and the extraction solution and cleaned soil and a process for ejecting cleaned soil from the nozzle to fill the space 5.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a soil purification method and a soil purification apparatus, and more particularly, to a soil purification method and a soil purification method capable of efficiently purifying contaminated soil located below uncontaminated soil. The present invention relates to a soil purification device suitably used in a purification method.

[0002]

2. Description of the Related Art In recent years, purifying soil contaminated with heavy metals such as cadmium and organic compounds such as trichloroethylene has become an important issue. As a general method of purifying contaminated soil, there is a method of excavating contaminated soil and removing contaminants in the excavated contaminated soil.

[0003]

However, according to the above-mentioned method for purifying contaminated soil, if uncontaminated soil is present in the upper layer of contaminated soil, the uncontaminated soil must be moved before being moved to the lower layer of the uncontaminated soil. Can not purify contaminated soil. For this reason, it is necessary to provide a process for moving uncontaminated soil, such as a process for excavating uncontaminated soil that does not need to be purified and a process for backfilling the space formed by excavating uncontaminated soil. And it takes a lot of trouble.

[0004] The present invention has been made in view of the above circumstances, and it is an object of the present invention to provide a soil purification method capable of efficiently purifying contaminated soil located below uncontaminated soil. Another object of the present invention is to provide a soil purification apparatus suitably used in the above soil purification method.

[0005]

In order to solve the above-mentioned problems, a soil purification method according to the present invention is a soil purification method for purifying contaminated soil located below uncontaminated soil using a soil purification device. Rotating a rotary shaft that constitutes an excavation section of the soil purification device to form a drilling hole having a depth at which a nozzle provided on the rotary shaft reaches the contaminated soil; and rotating the rotary shaft. By injecting water and air at a high pressure from the nozzle while forming, excavating the contaminated soil to form a space, discharging the contaminated soil with water as cutting earth and sand through the excavation hole, A step of performing a process of extracting contaminants contained in the cutting soil, and a step of solid-liquid separating the cutting soil after the extraction process into a liquid containing the contaminants and water and purified soil.
Injecting the purified soil from the nozzle to backfill the space.

According to such a soil purification method, it is possible to purify the contaminated soil located below the uncontaminated soil without moving the uncontaminated soil. There is no need to provide a process for moving uncontaminated soil, which has been a problem because it takes much time and effort. Therefore, the contaminated soil located below the uncontaminated soil can be efficiently purified. further,
In the above-mentioned soil purification method, when excavating contaminated soil, the contaminated soil is finely crushed and dispersed in water, and contaminants contained in the contaminated soil can be easily brought into contact with the extraction solution in the step of performing the extraction treatment. Therefore, the contaminants contained in the contaminated soil can be easily and reliably brought into contact with the extraction solution, and the contaminants contained in the contaminated soil can be extracted very effectively.

Further, in the above-mentioned soil purification method, the nozzle comprises two sets of nozzles provided at intervals in the longitudinal direction of the rotating shaft, and one of the two sets of nozzles is provided. It is desirable to perform backfilling in the space by injecting the purified soil from the other set of nozzles while forming the space by injecting water and air at a high pressure from the nozzles.

According to such a soil purification method, since the space can be backfilled while the space is formed, the contaminated soil located below the uncontaminated soil can be more efficiently purified. be able to.

In the above soil purification method, it is preferable that the extraction treatment is performed using an aqueous solution containing at least one selected from chelating agents, acids, alkalis and salts. By adopting such a soil purification method, contaminants contained in contaminated soil can be effectively and easily extracted.

[0010] In order to solve the above problems, a soil purification apparatus of the present invention has a rotating shaft and a nozzle provided on the rotating shaft, and water and air are supplied from the nozzle while rotating the rotating shaft. It is possible to excavate locally by injecting at high pressure, it is possible to locally backfill by injecting soil from the nozzle while rotating the rotating shaft, and A driving unit that drives the excavation unit, a supply unit that supplies the water, the air, and the soil injected from the nozzle, a discharging unit that discharges the cut soil excavated by the excavation unit, and a cutting unit that is included in the cut soil. Extraction processing means for performing extraction processing of pollutants;
And solid-liquid separation means for separating the cut soil after the extraction processing into liquid and purified soil.

The above-mentioned soil purification apparatus can excavate locally by injecting water and air at a high pressure from the nozzle while rotating the rotating shaft. Purification of contaminated soil located in the lower layer of uncontaminated soil without moving uncontaminated soil, because it has an excavated part that can be backfilled locally by spraying soil It is not necessary to provide a step for moving uncontaminated soil unlike the conventional soil purification method. Therefore, if the above-mentioned soil purification device is used, it is possible to efficiently purify the contaminated soil located below the uncontaminated soil.

In the above soil purification apparatus, the nozzles are two sets of nozzles provided at intervals in the longitudinal direction of the rotating shaft, and of the two sets of nozzles,
Desirably, one set of nozzles performs excavation and the other set of nozzles performs backfill.

[0013] Since such a soil purification apparatus is capable of backfilling the space while forming the space, the soil purification device located below the uncontaminated soil is more efficiently purified. It is possible to

In the above-mentioned soil purification apparatus, each of the two sets of nozzles may be composed of one nozzle or a plurality of nozzles. Determined according to conditions.

[0015]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below in detail.
However, the embodiments described below are specifically described for easy understanding of the purpose of the present invention, and do not limit the present invention unless otherwise limited. 1 to 6 are diagrams for explaining an example of the soil purification method of the present invention, and FIGS. 1 to 5 are schematic diagrams showing the purification status of contaminated soil. It is a flow chart for explaining a process after having discharged as cutting earth and sand.

1 to 5, reference numeral 20 denotes a soil purification apparatus of the present invention. This soil purification device 20
Is a drive unit 21, a digging unit 22, a supply unit 23, a pump 3 serving as a discharging means for discharging the cut sand excavated by the digging unit 22, and a diagram for performing a process of extracting pollutants contained in the cut sand. Extraction means, and solid-liquid separation means (not shown) for separating the cut soil into liquid and purified soil.

The excavating section 22 includes a rotating shaft 22c and a rotating shaft 2c.
2c. The nozzles are composed of two sets of nozzles, an upper nozzle 22a and a lower nozzle 22b, which are provided at intervals in the length direction of the rotating shaft 22c. Of the two sets of nozzles, the upper nozzle 22a is excavated. The lower nozzle 22b performs backfilling. The drive unit 21 is provided with a motor and the like, and drives the excavation unit 22. The supply unit 23 supplies water, air, and purified soil injected from the upper nozzle 22a or the lower nozzle 22b.

Next, a method for purifying the contaminated soil 1 located below the uncontaminated soil 6 by using the soil purifying apparatus 20 will be described in detail. First, the soil purification device 20
Is set on the uncontaminated soil 6 located in the upper layer of the contaminated soil 1. Then, as shown in FIG. 1, the rotary shaft 22 c of the soil purification device 20 is rotated to form the excavation hole 4 having a depth at which the upper nozzle 22 a reaches the lower end 1 b of the contaminated soil 1.

Subsequently, water and air are supplied from the supply unit 23 into the excavation unit 22, and the excavation unit 22 is raised.
As shown in FIG. 2, by injecting water and air from the upper nozzle 22 a at a high pressure while rotating the rotating shaft 22 c, the contaminated soil 1 located below the uncontaminated soil 6 is locally excavated to form a space. 5 is formed. At this time, contaminated soil 1
Is finely crushed and dispersed in water, so that the contaminants contained in the contaminated soil 1 can easily come into contact with the extraction solution in the step of performing the extraction process (described later).
Then, the excavated contaminated soil 1 is combined with water with the excavated hole 4
Is discharged onto the uncontaminated soil 6 via the pump 3, and is discharged as the cut soil 1c using the pump 3.

Then, the excavation of the contaminated soil 1 is advanced, and the excavation part 22 is gradually raised at a speed according to the excavation condition of the contaminated soil 1 so that the lower nozzle 22b reaches the lower end 1b of the contaminated soil 1 ( When the depth reaches the bottom of the space 5), backfilling in the space 5 is started as shown in FIG.

For backfilling in the space 5, purified soil obtained by purifying the contaminated soil 1 is used. As shown in FIG. 6, the purified soil is separated from the liquid (S6) containing the pollutant and the extraction solution by subjecting the cut soil 1c (S1) to an extraction treatment (S2) and solid-liquid separation (S3). It was obtained.

The extraction process here is performed, for example, by a method of mixing water containing cutting soil 1c discharged through the borehole 4 with the extraction solution. As the extraction solution used in the above-mentioned extraction treatment, any extraction solution having an action of extracting contaminants contained in the contaminated soil 1 can be used, but a chelating agent, an acid, an alkali, or a salt may be used. Preferably, the aqueous solution contains at least one selected from the group consisting of:

Specifically, for example, when the contaminants contained in the contaminated soil are heavy metal cations such as Cd ²⁺ , Pd ²⁺ , Zn ²⁺ and Cu ²⁺ , the pH of the contaminants is about 3 to 5; A mixed solution of an acid and a complex salt (Cl ⁻ , EDTA, citric acid) is desirable. When a mixed solution of an acid and a complex salt is used as an extraction solution, the acid and the complex salt may be mixed to form a mixed solution, and then mixed with water containing the cutting soil 1c.
The acid and the complex salt may be separately added to and mixed with the water containing the cutting soil 1c. Specifically, for example, the complex salt is added at a predetermined ratio to the water containing the cutting soil 1c, and the acid is added while mixing. May be added to adjust the pH to 3 to 5. More specifically, 58 g of sodium chloride is added to 1 liter of water containing cutting soil 1c, and sulfuric acid is added thereto while mixing to adjust the pH to 3 to 1.
It may be five.

When the contaminants contained in the contaminated soil are heavy metal anions such as chromic acid, arsenous acid, arsenic acid, selenic acid and selenious acid, the pH of the extraction solution is adjusted to pH1.
It is desirable to use a mild acid or alkaline solution with a pH of 11 or higher. When the contaminant contained in the contaminated soil is mercury, it is desirable to use a mixed solution of I ₂ and I ⁻ as an extraction solution.

Further, the solid-liquid separation here is performed by a method utilizing a filter press or the like, for example. The purified soil (S4) thus obtained is supplied to the supply unit 23
3, and is injected from the lower nozzle 22 b and locally buried in the space 5 as shown in FIG. 3 (S <b> 5) to form the formation 10.

Then, while the excavation of the contaminated soil 1 by the upper nozzle 22a proceeds, the space 5 by the lower nozzle 22b is increased.
In the inside of the contaminated soil 1, the excavation part 22 is further raised at a speed corresponding to the excavation state, and the upper nozzle 22a
When the depth reaches the upper end 1a of the contaminated soil 1, the excavation of the contaminated soil 1 ends. Thereafter, only the backfilling in the space 5 by the lower nozzle 22b is advanced, and the excavation part 22 is further raised at a speed according to the backfilling situation, and as shown in FIG. When the depth reaches the upper end 1a (the depth reaching the ceiling of the space 5),
The backfill in the space 5 ends.

Thereafter, the excavating part 22 is further raised,
By performing backfilling in the excavation hole 4, purification of the contaminated soil 1 is completed.

According to such a soil purification method, it is possible to purify the contaminated soil 1 located below the uncontaminated soil 6 without moving the uncontaminated soil 6. The located contaminated soil 1 can be efficiently purified. Further, in the above soil purification method, when excavating the contaminated soil 1, the contaminated soil 1 is finely crushed and dispersed in water, and contaminants contained in the contaminated soil are easily brought into contact with the extraction solution in the step of performing the extraction treatment. As a result, the pollutants contained in the contaminated soil 1 can be easily and reliably brought into contact with the extraction solution, and the contaminants contained in the contaminated soil 1 can be extracted very effectively.

The nozzle is composed of two sets of nozzles, an upper nozzle 22a and a lower nozzle 22b, which are provided at intervals in the longitudinal direction of the rotating shaft 22c.
a, while the space 5 is formed by injecting the extraction solution and air at a high pressure, the purified soil can be injected from the lower nozzle 22b to backfill the space. The contaminated soil 1 located in the lower layer can be more efficiently purified.

Further, the above-mentioned soil purification apparatus has a rotating shaft 22.
It is possible to excavate locally by injecting water and air at a high pressure from the upper nozzle 22a while rotating the lower nozzle 2c while rotating the rotating shaft 22c.
2b, the soil is provided with the excavated portion 22 that can be locally backfilled by injecting the soil, so that the contaminated soil located below the uncontaminated soil 6 without moving the uncontaminated soil 6 1 can be purified, and the contaminated soil 1 located below the uncontaminated soil 6 can be efficiently purified.

In the above soil purification method, while the space 5 is formed by injecting water and air at a high pressure from the upper nozzle 22a, the purified soil is ejected from the lower nozzle 22b to fill the space. Although the back was performed, the space 5 may be formed by injecting water and air at high pressure from the upper nozzle 22a, and then the purified soil may be injected from the lower nozzle 22b to backfill the space. . In this case, the jetting of water and air at high pressure and the jetting of the purified soil may be performed by one nozzle, and the rotary shaft 22c may be provided with one nozzle.

[0032]

As described above in detail, according to the soil purification apparatus and the soil purification method using the same of the present invention, the contaminated soil located below the uncontaminated soil without moving the uncontaminated soil. , It is possible to efficiently purify contaminated soil located below the uncontaminated soil.

Further, in the above soil purification method, when excavating the contaminated soil, the contaminated soil is finely crushed and dispersed in water, and the contaminants contained in the contaminated soil are easily mixed with the extraction solution in the step of performing the extraction treatment. As a result, the contaminants contained in the contaminated soil can be easily and surely brought into contact with the extraction solution, and the contaminants contained in the contaminated soil can be extracted very effectively.

[Brief description of the drawings]

FIG. 1 is a schematic diagram showing the purification status of contaminated soil,
It is the figure which showed the state which forms an excavation hole.

FIG. 2 is a schematic diagram showing the purification status of contaminated soil,
It is the figure which showed the state which excavates contaminated soil.

FIG. 3 is a schematic diagram showing the purification status of contaminated soil;
It is a figure showing the state where excavation of contaminated soil and backfilling in space are performed simultaneously.

FIGS. 1 to 5 are schematic diagrams showing a purification state of contaminated soil, and are diagrams showing a state in which backfilling in a space is performed.

FIGS. 1 to 5 are schematic diagrams showing a purification state of contaminated soil, and are diagrams showing a state in which backfilling in a space is completed.

FIG. 6 is a flowchart for explaining a process after discharging contaminated soil as cutting soil.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Contaminated soil 1a Upper end 1b Lower end 1c Cutting sand 3 Pump 4 Drilling hole 5 Space 6 Uncontaminated soil 10 Created body 20 Soil purification device 21 Drive unit 22 Drilling unit 22a Upper nozzle 22b Lower nozzle 22c Rotating shaft 23 Supply unit

Continued on the front page F term (reference) 2D043 CA01 4D004 AA41 AB03 AB06 AC07 CA13 CA34 CA50 CC03 CC06 CC11 CC12 4D056 AB08 AB17 AC04 AC09 AC11 AC25 CA17 CA31

Claims (5)

[Claims] 1. A soil purification method for purifying contaminated soil located below an uncontaminated soil using a soil purification device, comprising: rotating a rotary shaft that constitutes an excavation part of the soil purification device; Forming a drilling hole having a depth at which the nozzle provided in the contaminated soil reaches the contaminated soil, by injecting water and air from the nozzle at a high pressure while rotating the rotating shaft, the contaminated soil is Excavating to form a space, discharging the contaminated soil with water as cutting soil through the drilling hole, performing a process of extracting contaminants contained in the cutting soil, and A step of solid-liquid separating the cut soil and sand into a liquid containing the contaminant and water and a purified soil; and a step of injecting the purified soil from the nozzle to backfill the space. Soil purification method, characterized. 2. The nozzle comprises two sets of nozzles provided at intervals in the longitudinal direction of the rotary shaft, and water and air are supplied from one of the two sets of nozzles. 2. The soil purification method according to claim 1, wherein the backfill in the space is performed by ejecting the purified soil from another set of nozzles while forming the space by injecting the space at a high pressure. 3. 3. The soil purification method according to claim 1, wherein the extraction treatment is performed using an aqueous solution containing at least one selected from a chelating agent, an acid, an alkali, and a salt. . 4. It has a rotating shaft and a nozzle provided on the rotating shaft, and it is possible to excavate locally by jetting water and air from the nozzle at a high pressure while rotating the rotating shaft. And an excavation unit capable of locally backfilling by injecting soil from the nozzle while rotating the rotating shaft; a driving unit for driving the excavation unit; and A supply unit that supplies water, the air, and the soil; a discharge unit configured to discharge the cut sand excavated by the excavation unit; an extraction processing unit configured to perform a process of extracting contaminants contained in the cut soil; A soil-purifying device comprising: solid-liquid separating means for separating the later cut soil into liquid and purified soil. 5. The nozzles are two sets of nozzles provided at intervals in the length direction of the rotating shaft, and one of the two sets of nozzles excavates. The soil purification apparatus according to claim 4, wherein the other set of nozzles performs backfilling.