JP2000210652A - Method for detoxicating polluted soil - Google Patents

Abstract

PROBLEM TO BE SOLVED: To sufficiently mix polluted soils with liquid, powdery, or granular chemicals by constituting a mixer so that plural agitation rollers in which many rotary blades are fitted to a rotating shaft almost orthogonal to the transfer direction of the polluted soils are provided in a main body part in which polluted soils and a detoxicating agent are mixed and transferred. SOLUTION: The cylindrical main body part 2 of the mixer 1 is provided with rising parts 3 therein. Three agitation rotors 4 are provided, and are provided with many rotary blades 5 respectively. A spray nozzle 8 is provided in the upper part of the main body part 2 and a hose for injecting liquid is connected to the spray nozzle 8. When soils are charged from an introducing port 6, the soils are transferred downward and then backward by the first rotor 4. Then the soils are mixed with liquid chemicals from the spray nozzle 8. Next, when the soils come to near the next agitation rotor 4, the soils are scraped upward and mixed while a part thereof is returned forward, and the soils detoxicated by mixing are discharged from a discharge port 7.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

TECHNICAL FIELD The present invention relates to a method for detoxifying contaminated soil.

[0002]

2. Description of the Related Art Recently, there has been a great deal of interest in soil contamination, and there has been a problem of how to detoxify contaminated soil. The cause of soil contamination is due to the deliberation or negligence of factory effluents and chemicals in the factory premises and the dumping of substances which were then believed to be completely harmless.

[0003] When such a place becomes a residential land or a park due to the eviction of a factory or the like, it often comes to light by investigating the degree of soil contamination. Pollutants include heavy metals, organic chemicals (PCB, dioxin, etc.)
There are many. If such soils are not detoxified, they cannot be used not only as farmland, residential land and parks, but also as factories.

[0004] For such detoxification, it is most desirable to remove the cause of contamination. However, as a practical matter, it is impossible to selectively remove substances of the PPM unit and the PPB unit in the soil, so the entire soil must be replaced. Contaminated soil must be disposed of somewhere after replacement, which is a very expensive operation.

Therefore, a detoxifying agent (neutralizing agent) is added to the contaminated soil.
Has been adopted to make the pollutants harmless. This includes oxidizing or reducing contaminants to make them harmless, binding to other molecules or decomposing them to make them harmless. There are methods to prevent this.

[0006]

In any of the above methods, the degree of mixing of the contaminated soil and the chemical becomes a problem because the contaminant and the detoxifying chemical must react. That is, if the mixing is insufficient, the contaminants do not come into contact with the drug and are not rendered harmless. In particular, when the concentration of the contaminant is lower than PPM, this problem becomes serious.

[0007] In the conventional mixing method, contaminated soil is excavated and put into a container, a chemical is added thereto, mixed, taken out and backfilled. However, this was troublesome and time consuming. That is, continuous operation cannot be performed, and the system is of a batch type and is inefficient.

[0008] Therefore, there has been a long-awaited need in the art for a method that can be easily mixed with soil, can be sufficiently mixed with liquid, powdery or granular chemicals, and can be easily rendered harmless.

[0009]

Means for Solving the Problems In view of the above-mentioned situation, the present inventors have completed the method of the present invention as a result of intensive studies. A method of mixing and detoxifying a liquid or powder detoxifying agent in a mixer to detoxify contaminants, as the mixer, an inlet for introducing contaminated soil, a detoxifying agent inlet,
A main body for mixing and transferring the contaminated soil and the detoxifying agent, a main body provided on the main body, having a rotation axis substantially perpendicular to a direction in which the contaminated soil is conveyed, and having a number of rotary blades attached to the rotation shaft; A plurality of agitating rotors, and a discharge port for discharging the soil from the main body, wherein the plurality of agitating rotors are provided on different rotating shafts, respectively, and a plane including the plurality of agitating rotors Is to use a device that is horizontal or within 45 ° of horizontal and whose plane is substantially parallel to the direction of soil transport.

[0010] The contaminated soil is contaminated soil, regardless of the content and degree of the contamination. In short, it refers to soil that adversely affects the environment, such as the human body, livestock, and plants, as it is. In addition, the cause of the contamination does not matter. For example, it is the site of a factory, the inflow of pollutants from rivers, or it is completely natural. Therefore, soil improvement in a broader sense (improvement when harmless, but better farmland is desired)
Is also included. That is, farmland before improvement is included in the concept of contaminated soil.

The contaminants include so-called harmful substances such as heavy metal ions and dioxins, and acidic components in acidic soil. Of course, there may be more than one.

A detoxifying agent is a chemical for rendering a contaminant harmless by various methods (reactions) such as the above-described oxidation, reduction, neutralization, decomposition, bonding, etc., and a substance suitable for the contaminant may be employed. I just need. Of course, it may contain a plurality of types. Detoxification includes not only preventing the human body and the like from being adversely affected, but also includes soil improvement as described above. The detoxifying agent may be liquid or powder (including granular).

In addition, the present invention uses a special mixer having high mixing efficiency in view of the difficulty of mixing soil and liquid or powder. This special mixing machine is provided with an inlet for introducing contaminated soil, a detoxifying agent inlet, a main body in which the contaminated soil and the detoxifying agent are mixed and transferred, and a transfer direction of the contaminated soil and the main body. It comprises a plurality of agitating rotors having a substantially right-angled rotating shaft, and a number of rotating blades attached to the rotating shaft, and a discharge port for discharging the soil from the main body. On a different rotation axis, the plane containing the plurality of stirring rotors is horizontal or within 45 ° from the horizontal, and the plane is substantially parallel to the direction of soil transport.

The inlet is an opening for introducing soil into the main body, and is merely an opening and does not need to be special. The position of the inlet is preferably on the upstream side of the stirring rotor described later, but may be on the stirring rotor.

The detoxifying agent injection port is an opening for introducing a drug. In the case of a liquid, a nozzle, particularly a spray nozzle, is preferable, and one or a plurality of nozzles may be used. The mounting location is preferably the upper portion of the main body, which will be described later, and is preferably located on the upstream side as much as possible. When the drug is a powder or a granule, it may be a mere opening or a nozzle or the like when injected with compressed air. This detoxifying agent injection port does not have an independent one, and may serve also as the above-mentioned introduction port. Therefore, it is necessary to put the medicine through the inlet or spray the soil and put the soil through the inlet.

The main body is a portion where the soil is mixed,
It is also a part that transfers soil for continuous operation. It consists essentially of a simple container and a stirring rotor. The shape of the container itself may be cylindrical, rectangular, or the like.

The stirring rotor is an essential part of the special mixer. In this case, a rotary blade having a large number of widths is attached to a rotary shaft. The rotary blade here is not necessarily curved like a blade of an electric fan, but may be substantially planar. This is a completely different point from the conventional rotor. This rotary blade has a certain thickness (about several millimeters to several centimeters), and is a method in which the soil is kicked backward by the thickness. Therefore, the rotation axis of the rotary blade is provided at right angles to the soil transfer direction.

At least two stirring rotors are required. If there are two or more, any number is theoretically possible. In the experiment of the inventor, in the case of two stirring rotors, the rotation direction may be either direction. That is, the stirring rotor may be rotated in the opposite direction or in the same rotation direction. However, the upstream agitating rotor was in the direction of sending the soil backward below the rotor, and the downstream rotor rotated in the opposite direction.

Further, the rotation speed of the stirring rotor of the present invention is free, and may be all the same or different. In the experiment of the inventor, it was preferable that the discharge side was larger than the introduction side. The meaning is as follows. 1) The rotation direction of each stirring rotor does not matter. That is, the rotation speed here is an absolute value of the rotation speed, and does not say directional plus or minus. 2) The phrase “the outlet side is larger than the inlet side” means that the plurality of stirring rotors do not have to be sequentially faster, but may have the same speed. But nothing slows down. After all, when comparing the beginning and the end, it means that the end is faster and is not slower on the way.

Further, in the present special mixer, the plane including the plurality of stirring rotors is all horizontal,
It is within 5 °. In addition, this plane is disposed so as to be substantially parallel to the soil transfer direction. This is because the soil is transported and mixed at an angle of horizontal or within 45 ° from the horizontal, which is a major feature. For example, a method in which the soil is dropped from above by gravity and a mixing wing is provided in the middle of the fall may be considered, but this point is fundamentally different from this. In this mixer, the transfer of the soil (advancing from the device toward the discharge port) is performed by the stirring rotor, and is not dropped.

The present mixer is new in that soil is transferred by a stirring rotor. In particular, the stirring rotor can be moved backward despite the counter rotation of the stirring rotors, which is optimal for the mixing method as in the present invention.

In the present mixer, it is practically preferable that all of the plurality of stirring rotors are provided on the same plane, and all of them are parallel to the bottom surface of the main body (not the bottom surface but the transfer bottom surface). Then, the device is installed horizontally. With this configuration, the bottom surface of the main body and all of the plurality of stirring rotors are horizontal, and the direction in which the soil is transported is substantially parallel to the plane including the stirring rotor. However, as will be described later, the whole body can be freely inclined to some extent depending on the properties of the soil and the like.

Although the stirring rotor of the present mixer is as described above, an additional stirring rotor may be provided.

A large number of rotary blades are mounted on the rotary shaft while changing their positions. This is because if they are all at the same position, they will be like a single plate and the mixing efficiency will be poor. The position itself may be completely random or may vary to some extent regularly.

The rotary blade may be a simple steel plate as long as it has a certain thickness, but a hard material may be separately attached to the tip end portion to provide strength. Also, the shape may be triangular, rectangular, or the like. It is also preferable to reinforce the base so as not to break or to make it thicker. The angle of attachment of the rotary blade may be in the radial direction of rotation or may have a slight angle with the radial direction.

The outlet is a mere discharge opening as opposed to the inlet. The position is also downstream of the last stirring rotor,
It may be below the rotor.

In the present mixer, the rotation speed and the rotation direction may be adjusted appropriately depending on the particle size and viscosity of the soil. However, the entire body may be inclined due to the problem of the soil discharge speed. For example, if the material is highly viscous and difficult to transfer, it is preferable to increase the transfer efficiency by lowering the discharge port side, and to increase the mixing efficiency by slightly increasing the discharge port side in the case of sand. The inclination can be easily achieved with a normal hydraulic jack or the like. However, the inclination angle is preferably within 30 ° from the horizontal plane. This is because, if the inclination is further increased, the mixing efficiency of the mixture becomes worse. However, if it is within 45 °, the efficiency is reduced but it is possible. If the angle exceeds 45 °, the soil proceeds like falling, and the mixing ratio is extremely reduced.

[0028]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, a mixer used in the present invention will be described in detail based on an embodiment shown in the drawings. FIG.
1 is a sectional view showing an example of a mixer 1 suitable for the present invention. The main body 2 has a cylindrical shape, but has a raised portion 3 inside.
(This may be omitted). In this example, three stirring rotors 4 are provided, and a plurality of rotary blades 5 (only one is shown here) are provided. In the example of this figure, the leftmost stirring rotor rotates counterclockwise. The other stirring rotors alternately rotate reversely. Inlet 6
Is provided above the left rotor, and the discharge port 7 is provided below the right rotor. In this example, the main body is designed so that the rotation volume and the main body volume of the stirring rotor are substantially the same. In this example, the plane including the plurality of stirring rotors is parallel to the bottom surface of the main body, and both are horizontal because the main body is substantially horizontal.

A spray nozzle 8 is provided on the upper part of the main body 2. This sprays a liquid drug. A hose 9 for pressurizing the liquid is connected to the nozzle 8. Of course, in the case of a powdery drug, it may be a mere opening, in which case it may be manually inserted from a funnel or the like.

In this example, when soil is introduced from the inlet 6, the soil is transferred downward and backward by the first stirring rotor. Then, it is mixed with the liquid medicine from the spray nozzle 8. Next, when it comes to the vicinity of the next stirring rotor, it is scraped upward, and a part thereof is mixed while returning to the front. At this time, the soil does not completely follow the rotation of the agitation rotor, but a part of the soil collides with the wall surface, and a part of the soil falls and moves randomly, so that mixing occurs.
In this example, the main body is placed horizontally, but the outlet side is slightly raised to improve the mixing, and the outlet side is lowered to increase the transfer speed. The overall direction of transport of the mixture is parallel to the plane containing the three stirring rotors.

FIG. 2 shows one of the stirring rotors 4 of the mixer 1.
It is a conceptual perspective view showing an example. Rotary blade 1 on rotary shaft 10
It can be seen that 1 is randomly attached. However, in this figure, the thickness of the rotary blade 11 is ignored, and the distance between the rotary blades is greatly exaggerated. As described above, the attachment positions of the rotary blades 11, that is, the mutual positional relationship, may be not such random, but may be spiral or partially regular. Further, in this figure, one rotary blade exists on the same plane, but a plurality of rotary blades may be provided.

[0032]

The method and apparatus of the present invention have the following advantages. 1) In the method of the present invention, the liquid or powdery chemical is very well mixed with the excavated soil, and unnecessary chemicals are not required. Therefore, it is possible to reduce waste of cost caused by excessively adding a detoxifying agent and adverse effects on the environment due to the cost. 2) Since the soil can be easily detoxified, the land can be effectively used. 3) It can be implemented on site by simply loading a mixer. In addition, excavated soil may be collected at a treatment plant, rendered harmless, and then brought back to the site.

[Brief description of the drawings]

FIG. 1 is a schematic sectional view showing one example of a mixer that can be used in the present invention.

FIG. 2 is a conceptual perspective view showing an example of a stirring rotor of the mixer shown in FIG.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Mixer 2 Main body part 3 Rise part 4 Stirring rotor 5 Rotary blade 6 Inlet 7 Discharge port 8 Spray nozzle 9 Hose 10 Rotary shaft 11 Rotary blade

Claims (2)

[Claims] 1. A method for excavating contaminated soil and mixing it with a liquid detoxifying agent for detoxifying contaminants in a mixer to detoxify the soil, wherein the mixer is an inlet for introducing contaminated soil, A detoxifying agent inlet, a main body in which the contaminated soil and the detoxifying agent are mixed and transferred, a main body provided with a rotating axis substantially perpendicular to the transfer direction of the contaminated soil, and A plurality of agitating rotors to which a number of rotating blades are attached, and an outlet for discharging the soil from the main body, wherein the plurality of agitating rotors are provided on different rotating shafts respectively. A method for detoxifying contaminated soil, characterized by using a device in which a plane including the agitating rotor is horizontal or within 45 ° from the horizontal, and the plane is substantially parallel to the soil transfer direction. 2. A method for excavating contaminated soil, mixing it with a powdered detoxifying agent for detoxifying contaminants in a mixer and detoxifying the same, wherein the mixer is an inlet for introducing contaminated soil. A detoxifying agent injection port, a main body in which the contaminated soil and the detoxifying agent are mixed and transferred, a rotary shaft provided on the main body, and having a rotation axis substantially perpendicular to the direction of transfer of the contaminated soil, and A plurality of agitating rotors having a number of rotating blades attached thereto, and a discharge port for discharging the soil from the main body, wherein the plurality of agitating rotors are provided on different rotating shafts, respectively. A method for detoxifying contaminated soil, comprising using a device in which a plane including a plurality of agitation rotors is horizontal or within 45 ° from the horizontal, and the plane is substantially parallel to the direction of soil transport.