JP2004243192A - Method and system for treating contaminated soil and contaminated soil treatment machine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a contaminated soil treatment method for rapidly subjecting fluoride-contaminated soil to insolubilization treatment, a contaminated soil treatment system and a contaminated soil treatment machine. <P>SOLUTION: In a first process, excavated fluorine-contaminated soil is subjected to the mixing treatment with an aluminum sulfate solution and a calcium chloride solution, and fluorine in the fluorine-contaminated soil is insolubilized by the interaction of the insolubrization due to calcium chloride and the adsorption due to aluminum sulfate. In a second process, the mixed soil of the fluorine-contaminated soil, aluminum sulfate and calcium chloride subjected to mixing treatment in the first process is subjected to the mixing treatment with a solidifying material not only to be stabilized in properties but also to be adjusted in pH. <P>COPYRIGHT: (C)2004,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a method for purifying soil contaminated with fluorine, and more particularly, to a method for treating contaminated soil capable of insolubilizing fluorine-contaminated soil quickly at a work site, a soil treatment system, and a treatment machine.
[0002]
[Prior art]
As of February 22, 1999, Environmental Standards for Water Pollution (No. 59 of the Environment Agency, December 1967) and Environmental Standards for Water Pollution of Groundwater (No. 10, Notification of the Environment Agency in March 1997) ) Was revised, and fluorine was added to the items of environmental standards for human health protection, along with nitrate nitrogen, nitrite nitrogen and boron.
[0003]
Against this background, among the functions of soil as an environment, from the viewpoint of preserving the water purification and groundwater recharge functions, environmental standards for soil contamination based on the Basic Environment Law (1993 Law No. 91) (Heisei 5) On August 14, 1999, the Commissioner of the Environment Agency made a statement to the Central Environment Council on July 14, 1999, because the Environment Agency Notification No. 46 (hereinafter referred to as “Soil Environmental Standards”) is closely related to water quality conservation. On the other hand, he consulted on “Addition of environmental standards related to soil pollution” (Inquiry No. 77). On December 26, 2000, the Central Environmental Council's Soil Agrochemicals Subcommittee drafted a report on this consultation, and based on this report, in March 2001, new fluorine and other substances were added to the soil environmental standards. It has just been added.
[0004]
As described above, before March 2001, fluorine was not specified as a harmful substance in the soil environmental standards, and basic measures have not yet been established for the treatment of fluorine-contaminated soil. A first step of adding a mineral acid to adjust the pH to an acidic range of 2 to 4; a second step of adding and mixing an aluminum salt or an iron salt to the fluorine-contaminated soil adjusted to a weakly acidic range in the first step; It has been proposed to insolubilize fluorine in fluorine-contaminated soil by performing at least three steps: a third step of adjusting the pH to a weakly acidic to alkaline range of 3 to 10 by adding an alkali (patent). Reference 1).
[0005]
[Patent Document 1]
JP-A-2002-326081
[0006]
[Problems to be solved by the invention]
For example, manufacturing industries using fluorine in a production process include an electroplating industry, a semiconductor manufacturing industry, an electronic component manufacturing industry, and the like. For the electroplating industry, semiconductor manufacturing industry, electronic component manufacturing industry, etc., respective wastewater standards are set by the Water Pollution Prevention Law. Many companies did not take special measures to prevent the leakage of fluorine in wastewater because the substance was not specified. In addition, even if fluorine is naturally derived, if the elution amount exceeds a predetermined value, it is highly likely that the fluorine is not determined to be naturally derived. It is not desirable to handle soil that exceeds these soil environmental standards inappropriately, such as by carrying it out or disposing of it. And other measures are required.
[0007]
Furthermore, in recent years, when resold a former factory site, the owner is obligated by law to conduct a pollution survey of the former factory site and to purify the soil when contamination is found as a result. Also, if the land purchased is found to be contaminated with contaminants during resale after resale, a building will be built on that land unless the soil is cleaned up, even if it is under construction. The construction work has to be postponed or interrupted. In addition to these circumstances, there is often no room for the land preparation period due to contracts and construction plans when buying and selling land and building buildings, so promptness is required for soil purification processing. However, in the technique described in Patent Document 1, at least three steps are required to insolubilize the fluorine in the fluorine-contaminated soil, and furthermore, in order to actually reuse it as backfill soil or the like, it is necessary to further improve the process. It is necessary to perform the processing, and when the process requires a high speed due to the large number of steps, it is not always possible to cope with the case.
[0008]
The present invention has been made based on the above matters, and an object of the present invention is to provide a contaminated soil treatment method, a contaminated soil treatment system, and a contaminated soil treatment machine capable of quickly insolubilizing fluorine-contaminated soil. It is in.
[0009]
[Means for Solving the Problems]
In order to achieve the above object, a first aspect of the present invention provides a first step in which excavated fluorine-contaminated soil is stirred and mixed with an aluminum salt and a calcium salt, and a fluorine-contaminated soil mixed and mixed in the first step. And a second step of mixing and mixing the mixed soil of aluminum, calcium salt and aluminum salt with the solidifying material.
[0010]
In the second invention, the excavated fluorine-contaminated soil is mixed and treated with an aluminum salt and a calcium salt, so that the fluorine in the fluorine-contaminated soil is interacted with the insolubilization by the calcium salt and the adsorption by the aluminum salt. The first step of insolubilizing and the mixed soil of the fluorine-contaminated soil, aluminum salt, and calcium salt mixed and processed in the first step are mixed with a solidifying material to stabilize properties and adjust pH. And a second step to be performed.
[0011]
In these first and second inventions, in the first step, fluorine in the fluorine-contaminated soil is precipitated as calcium fluoride by a reaction with a calcium salt, and at the same time, one that does not completely react with the calcium salt is: Adsorbed on aluminum salts. Fluorine in the contaminated soil can be sufficiently insolubilized by the interaction of the calcium salt and the aluminum salt with the respective fluorine. Then, in the second step, by mixing with the solidifying material, the properties can be stabilized in a state in which the fluorine is insolubilized, and the required strength can be expressed, so that the predetermined curing period is reduced. After the elapse, it can be used as backfill soil without any further treatment. At this time, by appropriately adjusting the hydrogen ion concentration of the aluminum salt solution or the calcium salt solution, or both of the solutions, the treated soil generated in the second step is reduced to a hydrogen ion concentration at which fluorine is less likely to be re-eluted. Adjustment is also possible. In this way, only the first step of mixing and processing the excavated fluorine-contaminated soil with the aluminum salt and the calcium salt, and the second step of mixing and processing the solidified material, the fluorine-contaminated soil can be quickly removed. In addition, the insolubilization treatment can be sufficiently performed, the stability is good, and the handling at the time of backfilling can be in a good state.
[0012]
A third invention is characterized in that, in the first or second invention, a mixing device having a stirring means is used for the mixing process in at least one of the first and second steps.
[0013]
According to a fourth aspect of the present invention, in any one of the first to third aspects, the solidified material is any of a cement-based solidified material, a cement-lime composite-based solidified material, and a lime-based solidified material. And
[0014]
Further, a fifth invention provides a first mixing device for receiving excavated fluorine-contaminated soil, stirring and mixing the same with aluminum salt and calcium salt, and a fluorine-contaminated soil and aluminum salt discharged from the first mixing device. And a second mixing device for stirring and mixing the mixed soil of calcium salt and the solidified material.
[0015]
In a sixth aspect of the present invention, there is provided a hopper for receiving excavated fluorine-contaminated soil, an additive supply device for supplying an aluminum salt and a calcium salt to the fluorine-contaminated soil, and an aluminum salt and a calcium salt. A self-propelled insolubilizing machine having a mixing device that stirs and mixes the mixed soil, and discharge means for discharging the mixed soil from the mixing device outside the machine; A receiving hopper, a solidifying material supply device for supplying the solidified material to the mixed soil, a mixing device for stirring and mixing the mixed soil with the solidified material by a built-in stirring means, and discharging the treated soil from the mixing device outside the machine. And a self-propelled solidification processing machine having a discharging means.
[0016]
Further, a seventh invention provides a hopper for receiving excavated fluorine-contaminated soil, an additive supply device for supplying an aluminum salt and a calcium salt to the fluorine-contaminated soil, and a built-in stirring means for converting the fluorine-contaminated soil into an aluminum salt and an aluminum salt. It is characterized by comprising a mixing device for stirring and mixing with the calcium salt, and a discharging means for discharging the mixed soil from the mixing device to the outside of the machine.
[0017]
Further, the eighth invention is characterized in that the hopper receiving the mixed soil obtained by mixing the fluorine-contaminated soil, the aluminum salt, and the calcium salt, a solidified material supply device for supplying the solidified material to the mixed soil, and a built-in stirring means. The mixing device is provided with a mixing device for stirring and mixing the mixed soil with the solidified material, and a discharging means for discharging the processed soil from the mixing device to the outside of the machine.
[0018]
A ninth invention is characterized in that, in the seventh or eighth invention, a traveling means for enabling self-traveling is further provided.
[0019]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments of a method for treating contaminated soil, a treatment system, and a treatment machine according to the present invention will be described with reference to the drawings.
FIG. 1 is a block diagram showing a series of processing steps of a contaminated soil treatment system used in one embodiment of the contaminated soil treatment method of the present invention, and FIG. 2 is an example of a contaminated soil treatment system used in the contaminated soil treatment method of the present invention. It is a side view showing the whole structure. In FIGS. 1 and 2, reference numeral 1A denotes an insolubilization apparatus (contaminated soil treatment machine) for insolubilizing fluorine in fluorine-contaminated soil (contaminated soil) excavated by, for example, a hydraulic shovel, and 1B denotes an insolubilization apparatus 1A. This is a solidification treatment device (contaminated soil treatment machine) for solidifying discharged soil (mixed soil described later), and these are supported by base frames 2A and 2B. The base frame 2B is made of, for example, an H-shaped steel, and is arranged in the width direction (direction orthogonal to the paper surface of FIG. 2) so as to be substantially parallel to each other. 2 (right end in FIG. 2). Similarly, the base frame 2A is also made of, for example, an H-shaped steel, and is fastened to the opposite end (the left end in FIG. 2) of the base frame 2B by a bolt (not shown) or the like. The insolubilizing apparatus 1A is mounted on the base frame 2A and is fixed by, for example, bolts or the like.
[0020]
As shown in FIG. 2, the insolubilizing apparatus 1A includes a sieve device 3, a hopper 4, a transport conveyor 5, an additive supply device 6 (see FIG. 4 described later), a mixing device 7, a discharge conveyor 8, a power device 9, and It is schematically composed of a main body frame 10 that supports devices (the details of each device will be described later in order). The main body frame 10 is fastened (may be welded) on the base frame 2A by, for example, bolts or the like.
[0021]
FIG. 3 is a side view showing a detailed structure near the sieve device 3 and the hopper 4. The sieving apparatus 3 shown in FIG. 3 serves as a crushing and classifying means for receiving, for example, soil to be treated (fluorine-contaminated soil) excavated by a hydraulic shovel or the like, and crushing and classifying (sorting) according to the particle size. It fulfills. Reference numeral 11 denotes a frame constituting a main body of the sieving apparatus 3. The frame 11 is elastically supported via a spring 14 by a support member 13 provided on the main body frame 10 via a support post 12. ing. Reference numeral 15 denotes a grid member mounted in the frame 11, reference numeral 16 denotes a rotary drum having a vibration axis (not shown) of the grid member 15 inserted therein, and the rotary drum 16 is rotationally driven by a driving device (not shown). I do. With this configuration, the vibration shaft (not shown) is rotated to excite the sieving device 3, and large lumps and the like contained in the supplied fluorine-contaminated soil are broken by the edge effect of the grid member 15. I have. At this time, since the frame body 11 is disposed so that the front side (the left side in FIG. 3) is lower than the rear side (the right side in FIG. 3), a stone larger than the mesh of the grid member 15 included in the injected earth and sand is provided. Foreign substances such as move to the front side on the grid member 15 and are discharged outside the machine (in this case, the left side in FIG. 3), and components smaller than the mesh of the grid member 15 are selected and introduced into the lower hopper 4. It has become. Reference numeral 17 denotes a so-called swing provided on the upper portion of the sieve device 3.
[0022]
The hopper 4 is a frame-shaped member that receives the fluorine-contaminated soil introduced from the sieving device 3, and the upper end is fixed to the support member 13 so that the lower end is inclined according to the inclination angle of the conveyor 5. . The hopper 4 has an upwardly expanded shape in order to reliably receive the fluorine-contaminated soil from the sieving device 3. The dimension of the upper opening of the hopper 4 is slightly larger than the frame 11 of the sieve device 3 in both the longitudinal direction and the width direction, and the width of the lower end is set to the conveyor belt 24 of the conveyor 5 (see FIG. 4 described later). ) Is slightly smaller than the width. Thus, the fluorine-contaminated soil introduced from the sieve device 3 is guided onto the conveyor 5 without leaking. Although not shown in FIG. 2, in the present embodiment, water is added to the fluorine-contaminated soil in the hopper 4 in order to improve the familiarity between the fluorine-contaminated soil and the additive and facilitate the subsequent processing. A water supply channel 32aa (see FIG. 1) is provided.
[0023]
Reference numeral 18 denotes an arch breaker provided in the hopper 4. The arch breaker 18 penetrates in the longitudinal direction of the hopper 4 (horizontal direction in FIG. 3), and both ends of the hopper 4 are bearings (not shown). And a plurality of stirring rods 20 provided at a predetermined pitch in a state of being inclined at a predetermined angle in a direction orthogonal to the axial direction with respect to the rotation shaft 19. I have. A driving device 21 for the arch breaker 18 is directly connected to an end of the rotating shaft 19 (the right end in FIG. 3). With this configuration, the arch breaker 18 is rotationally driven by the driving device 21 and agitates the fluorine-contaminated soil introduced into the hopper 4 by the stirring rod 20 to prevent cross-linking from occurring in the lower portion inside the hopper 4 and to dissolve the soil mass. Crushing is promoted.
[0024]
Returning to FIGS. 1 and 2, the transport conveyor 5 is mounted on the front end (left side in FIG. 2) of the main body frame 10. The transport conveyor 5 extends slightly upward (preferably substantially horizontal) from below the hopper 4 toward the downstream side (the right side in FIG. 2).
[0025]
FIG. 4 is a diagram showing a detailed structure near the downstream side of the conveyor 5. In FIG. 4, reference numeral 22 denotes a conveyor frame of the conveyor 5, and reference numeral 23 denotes a driving wheel supported at a downstream (right side in FIG. 4) end of the conveyor frame 22. A transport belt 24 is wound around a driven wheel (not shown) supported at the upstream end (left end in FIG. 4). With this configuration, the driving wheels 23 are rotationally driven by a driving device (not shown), and the transport belt 24 is circulated. At this time, as shown in FIG. 4, an opening 4a having a predetermined opening area is provided on the downstream side wall surface of the hopper 4, and the fluorine-contaminated soil conveyed by the conveyor 5 passes through the hopper 4 through the opening 4a. 4 is cut out and guided to the mixing device 7. Although not particularly shown, in order to prevent slippage of the fluorine-contaminated soil, it is preferable to provide a so-called lug on the transport surface of the transport belt 24. Reference numeral 25 denotes a regulating plate for preventing the fluorine-contaminated soil cut out of the hopper 4 from spilling off from the conveyor 5.
[0026]
The additive supply device 6 includes supply pipes 27a to 27c, and the supply pipes 27a to 27c are supported by a frame 26 that extends over the regulating plate 25 of the transport conveyor 5 and the entrance 35 of the mixing device 7. .
[0027]
Here, in FIG. 2, reference numeral 28 denotes a pump unit for storing an additive used in the insolubilization apparatus 1A. The pump unit 28 includes storage tanks 29a to 29c and additives in the storage tanks 29a to 29c. Pumps 30a to 30c (see FIG. 1) that respectively discharge the pressure, a control panel (not shown), and a base frame 31 on which these are mounted. In the storage tanks 29a to 29c, water, an aluminum sulfate solution, and a calcium chloride solution are stored as additives, respectively. However, strictly speaking, the water plays a role of adjusting the water content for smoothing the insolubilization reaction of fluorine.
[0028]
The supply pipes 27a to 27c are connected to storage tanks 29a to 29c, respectively, and connection pipes 32a to 32c (see FIG. 1) are provided with on-off valves 33a to 33c, respectively (see FIG. 1). I have. For convenience, the pump unit 28 is shown in front of the insolubilization apparatus 1A in FIG. 2 (left side in FIG. 2), but in actuality, at this position, a means for feeding a fluorine-contaminated soil such as a hydraulic shovel is provided. Since it may be disposed, it may be disposed next to the insolubilization apparatus 1A (for example, on the back side or near side in the direction orthogonal to the paper surface of FIG. 2). In this embodiment, the pump unit 28 is separately installed. However, the pump unit 28 has a small size, for example, when the processing amount is comparatively small and the pump unit 28 is operated on site where a large amount of additives are not required. If it suffices, it may be configured to be appropriately incorporated into a contaminated soil treatment machine.
[0029]
FIGS. 5A and 5B are diagrams illustrating the structure of the supply pipes 27a to 27c. First, as shown in FIG. 5A, the supply pipe 27c (FIG. 5A shows the supply pipe 27c as an example, but the supply pipes 27a and 27b are the same). It has a central portion 27ca to which the connection pipe 32c is connected, and an end portion 27cb bent from the central portion 27ca, and is provided inside the central portion 27ca and the end portion 27cb. Is provided with a number of holes 34. The interval between the end portions 27cb (that is, the length of the approximately central portion 27ca) is substantially equal to the width of the inlet 35 (see FIG. 4) of the mixing device 7, and the hole 34 of the central portion 27ca faces the transport conveyor 5. In addition, it is attached to the frame 26 (see FIG. 4) by, for example, welding so as to be located almost directly above the entrance 35.
[0030]
Thereby, the additive supply device 6 causes the water, the aluminum sulfate solution, and the calcium chloride solution, which are pumped from the pump unit 28, to flow out through the holes 34 of the supply pipes 27a to 27c, respectively, and Fluorine-contaminated soil released from Japan is supplied from three directions. Then, the fluorine-contaminated soil and the additive are supplied to the mixing device 7.
[0031]
The supply pipes 27a to 27c may have a substantially "one" character shape as shown in FIG. 5B. In this case, the holes 34 are opposed to the conveyor 5 (strictly, It may be attached to the frame 26 so as to counteract the fluorine-contaminated soil discharged from the conveyor 5).
[0032]
Returning to FIGS. 1 and 2, the mixing device 7 is mounted on substantially the center of the main body frame 10 in the longitudinal direction (the left-right direction in FIG. 2), and on one side (left side in FIG. An inlet 35 (see FIG. 4) for the agent and an outlet (not shown) for the improved soil are provided at the lower part on the other side (right side in FIG. 2). Although not particularly shown for the purpose of preventing complexity, the mixing device 7 includes a plurality of paddle mixers (not shown, or a single paddle) provided substantially in parallel therein as stirring means. The mixed soil (a mixed soil of a fluorine-contaminated soil, water, an aluminum sulfate solution and a calcium chloride solution) is led out from the outlet while uniformly mixing and mixing the introduced fluorine-contaminated soil and the additive. A driving device 36 drives the paddle mixer.
[0033]
The discharge conveyor 8 discharges the mixed soil from the mixing device 7 outside the machine and supplies the mixed soil to the solidification treatment device 1B. The discharge conveyor 8 has a predetermined direction from below the outlet (not shown) of the mixing device 7 toward the other side (the right side in FIG. 2). After extending substantially horizontally by a distance, the mixing device 7 extends upward from a lower portion of the driving device 36. Reference numeral 37 denotes a frame of the discharge conveyor 8, and the conveyor frame 37 is supported by the power unit 9, the main body frame 10, and the like by support members (not shown).
[0034]
Although not shown, the power unit 9 is an engine as a power source of the drive unit of each device described above, a hydraulic pump driven by the engine, and hydraulic oil supplied from the hydraulic pump to the drive unit of each unit. A plurality of control valves and the like to be controlled are built in, and are supported via a support member 38 at the other longitudinal end (right side in FIG. 2) of the main body frame 10.
[0035]
The solidification treatment device 1B has the same configuration as the insolubilization treatment device 1A except that the sieve device 3 and the additive supply device 6 are omitted. Although the same reference numerals are given in FIG. 2 and the description is omitted, the configuration of the powder supply device 39 in which the description is omitted in the insolubilizing apparatus 1A will be described below. Here, the powder supply device 39 on the solidification treatment device 1B side will be described. However, as shown in FIG. 2, the powder supply device 39 is provided not only in the solidification treatment device 1B but also in the insolubilization treatment device 1A. The structure and the supporting structure are the same.
[0036]
The powder supply device 39 plays a role of a solidification material supply device that supplies the solidification material to the mixed soil from the insolubilization treatment device 1A in the solidification treatment device 1B, and includes a storage tank 40 for the solidification material and a storage tank 40 for the solidification material. And a feeder 41 for guiding the solidified material in the downward direction.
[0037]
The storage tank 40 includes a bottomed lower tank portion 42, a bellows-shaped upper tank portion 43 connected to the upper portion thereof, and an upper cover 44 of the upper tank portion 43. By configuring the upper tank portion 43 in a bellows-like manner, the storage tank 40 can be contracted. For example, at the time of transportation or the like, the total height is reduced to a height at which the transportation restriction is cleared. .
[0038]
The feeder 41 is a so-called rotary feeder, which is not particularly shown for the purpose of preventing complexity, but has a built-in rotor in which a plurality of partitions are radially protruded on a rotation shaft, and is introduced from the storage tank 40 into the space between the partitions. The solidified material is sequentially added to the fluorine-contaminated soil conveyed on the conveyor 5 (see also FIG. 4). However, in the present embodiment, the feeder 41 is a rotary feeder, but is not limited to this, and may be a screw feeder.
[0039]
When the contaminated soil treatment method of the present invention is performed using the contaminated soil treatment system having the above-described configuration, the contaminated soil treatment machine according to the present embodiment converts the fluorine-contaminated soil excavated with a hydraulic shovel or the like into an insolubilization treatment apparatus 1A. When it is thrown into the sieve device 3 (see FIG. 3), large stones, reeds and the like are removed by the grid member 15 (see FIG. 3), and the fluorine-contaminated soil component that has passed through the grid member 15 is introduced into the hopper 4. By this classification, the particle size distribution of the fluorine-contaminated soil can be made uniform, and the size can be easily mixed with the additive. At this time, when the lattice member 15 vibrates, the earth mass larger than the mesh of the lattice member 15 is jumped up and falls on the lattice member 15 again. By repeating such an operation, the earth mass is broken up by the impact at that time or the edge effect of the mesh (or a blade) of the grid member 15, and is introduced into the hopper 4 when it becomes smaller than the mesh of the grid 15. . The water in the storage tank 29a is sprinkled on the fluorine-contaminated soil received by the hopper 4 by the water supply line 32aa so that the fluorine-contaminated soil and the later additives become well-adapted. Is stirred.
[0040]
While the relatively large soil mass is broken by the arch breaker 18, the fluorine-contaminated soil placed on the conveyor 5 is cut out of the hopper 4 through the opening 4a (see FIG. 4). At this time, the fluorine-contaminated soil cut out of the hopper 4 is stirred by the arch breaker 18 at that time, and even if a relatively large soil mass remains, the soil mass is broken up here. Additives (insolubilizing agents, ie, an aluminum sulfate solution and a calcium chloride solution) are supplied to the fluorine-contaminated soil conveyed by the conveyor 5 and introduced into the mixing device 7 by the additive supply device 6. The fluorine-contaminated soil introduced into the mixing device 7 is uniformly stirred and mixed in the mixing device 7 (first mixing device) with the additive introduced together. The mixed soil mixed by the mixing device 7 is led out onto the discharge conveyor 8 and transported toward the solidification processing device 1B.
[0041]
The mixed soil supplied from the insolubilization device 1A is received by the hopper 4 of the solidification device 1B and is stirred by the arch breaker 18, where it is further adapted to the additive, and placed on the transport conveyor 5. . In the solidification treatment device 1B, the mixed soil placed on the transport conveyor 5 is transported rearward and cut out of the hopper 4. The solidified material in the storage tank 40 is supplied via the feeder 41 of the powder supply device 39 near the downstream end of the transport conveyor 5 in the transport direction. As described above, the mixed soil on the conveyor 5 is introduced into the mixing device 7 (second mixing device) together with the supplied solidified material, and the mixed soil and the solidified material are uniformly stirred and mixed in the mixing device 7. And finally discharged out of the machine via the discharge conveyor 8.
[0042]
As described above, in the present embodiment, the first step in which the excavated fluorine-contaminated soil is stirred and mixed with the aluminum sulfate solution and the calcium chloride solution by the insolubilization apparatus 1A, and the fluorine that has passed through the first step The second step of mixing and mixing the contaminated soil, the aluminum sulfate solution, and the calcium chloride solution together with the solidifying material to mix and insolubilize the fluorine-contaminated soil.
[0043]
In the first step, the fluoride ions in the fluorine-contaminated soil are
2F ⁻ + Ca ²⁺ → CaF ₂ ↓
As shown by the reaction, calcium fluoride (CaF) ₂ ) And at the same time, those that do not react with calcium chloride are adsorbed on aluminum sulfate. Such interaction of calcium chloride and aluminum sulfate with the respective fluorine brings the fluorine in the contaminated soil into a sufficiently insolubilized state.
[0044]
Further, in the second step, the mixed soil obtained by insolubilizing the fluorine contained in the first step is further mixed with a solidifying material. It is in a state covered with the solidified material. In addition to this, the soil to be treated in a state where the tissue has been destroyed by excavation or water addition is mixed with the solidified material, the tissue is restored, and the mixed soil mixed with the solidified material further solidifies the solidified material. The strength gradually develops (increases) due to the action, and after a predetermined curing period has elapsed, it can be used as backfill soil without any further treatment (handling property as backfill soil). Can be secured).
[0045]
Further, by performing the second step, the mixed soil having a low pH (a state in which fluorine is easily re-eluted as it is) by mixing with aluminum sulfate can be converted into a high-pH (alkaline) solidified material. By mixing with (for example, blast furnace cement B), it can be returned to almost neutral (pH adjusted), in which fluorine is hardly re-eluted. At this time, it is necessary to consider the addition amount of the solidifying material together with the addition amount of the additive in the first step. Hereinafter, this will be described.
[0046]
First, the present inventors verified the relationship between the pH of soil after the insolubilization treatment and the elution amount of fluorine as shown in FIG. 6 by experiments. The graph in FIG. 6 shows that the calcium-contaminated soil was mixed with 1.3 to 13 g, aluminum sulfate: 0.5 to 2.0 g, slaked lime: 2.5 to 10 g, and other slaked lime per 1 kg of the simulated test soil. Solidified material (neutral solidified material, zeolite, bentonite): It was obtained by measuring 50 g of fluorine elution amount at each pH value by mixing 50 g at different mixing ratios. The fluorine elution amount was measured based on the official method.
[0047]
According to the results of FIG. 6, in a certain range, the lower the pH value, the more the insolubilization reaction of fluorine progressed, and a value that cleared the soil environmental standard value (0.8 mg / L) near pH 6 was obtained. However, in the results of FIG. 6, the desirable value of the hydrogen ion concentration of the soil after the treatment was about pH 6, but the hydrogen ion concentration of the soil after the treatment was pH 5 to 7, depending on the fluorine concentration of the target soil. Alternatively, it is estimated that a pH of about 5 to 10 is sufficient. However, if the pH is lower than this range, depending on the target soil, the possibility of elution of other heavy metal contaminants increases, which is not preferable. As can be seen from No. 6, the fluorine insolubilization reaction hardly occurs, which is not preferable.
[0048]
As described above, in the present embodiment, by adding aluminum sulfate in the first step, the mixed soil once leans to acidic, but in the second step, neutrality is obtained by adding an alkaline solidifying material. You can return to the vicinity. Normally, the solidified material is mixed to stabilize the insolubilized state or to develop required strength to withstand backfill soil, but in the present embodiment, the insolubilized state is stabilized. The process up to the point where the required strength is developed is regarded as a process of purification treatment of the fluorine-contaminated soil, and the first and second processes are performed so that the hydrogen ion concentration of the treated soil is about pH 6 (in some cases, pH 5 to 10). The type and mixing ratio of additives and solidification materials in the process were determined. As a result, the properties of the mixed soil are stabilized in a state where the insolubilized fluorine is less likely to elute again.
[0049]
According to the present embodiment, as described above, the first step of mixing and processing the excavated fluorine-contaminated soil with aluminum sulfate and calcium chloride, and the second step of mixing and processing with the solidified material Only by performing the insolubilization treatment, it is possible to develop the optimum strength of the backfill soil without any special treatment thereafter. As described above, in the present embodiment, by only two processes, the fluorine-contaminated soil can be processed into a stable state in which fluorine is not easily eluted again, and the strength can be improved to a state in which handling is good, so that it is quick and sufficient. The insolubilization treatment of natural fluorine contaminated soil can be performed.
[0050]
According to the present embodiment, the following effects can be obtained in addition to the above effects. (1) Improve safety
In the technology described in Patent Document 1 described above, a mineral acid and an alkali are added for the purpose of adjusting the pH to promote the insolubilization of fluorine. In the present embodiment, it is not necessary to add a mineral acid or alkali having high danger to the environment for such pH adjustment, so that the fluorine-contaminated soil can be insolubilized safely and the load on the environment can be reduced. Can be reduced.
[0051]
(2) Mixing process by paddle mixer
According to the official method, a test solution for evaluating the insolubilized state of fluorine, which was newly added to the soil environmental standards, was 50 g of 50 g collected from air-dried target soil, granulated and subjected to particle size selection. A sample is prepared from a sample solution obtained by mixing with a solvent by a predetermined method. In an actual work site, only 50 g of the sample used for preparing the test solution is processed in spite of processing ton order target soil (fluorine-contaminated soil). Therefore, for example, in the first and second steps described above, considering the mixing ratio of additives and solidifying materials, even if theoretically the soil environmental standards as a whole should be sufficiently satisfied, When the mixing state of the agent and the solidifying agent with respect to the fluorine-contaminated soil is not uniform, there may be a case where the soil environmental standard is not satisfied only for the treated soil of 50 g provided for the sample. Therefore, it is desirable that the mixing state of the fluorine-contaminated soil and the additives and the like be as uniform as possible.
[0052]
On the other hand, in the present embodiment, a type having a paddle mixer as a stirring means inside is used as the mixing device. This type of so-called mixing type mixing apparatus has a paddle mixer in which a number of stirring blades (paddles) are implanted around a rotation axis in a main body. By rotating the paddle mixer, a mixing process taken in the main body is performed. It operates to sufficiently knead the object while stirring and breaking up the earth mass. In addition, by operating with the exit of the mixed soil open, the paddle mixer's sediment transfer function enables continuous processing, such as receiving raw materials, mixing and discharging soil from the exit, but batch processing with the exit closed. Is performed, the target object can be more sufficiently and surely uniformly stirred and mixed. Therefore, according to the present embodiment, by using the mixing device 7, the fluorine-contaminated soil can be uniformly and finely stirred and mixed to a sufficient level together with the additive and the solidifying material. Therefore, as long as the required amount of the additive and the solidifying material are supplied to the fluorine-contaminated soil, the soil environment standard value can be reliably cleared.
[0053]
(3) Compact system
In the present embodiment, the contaminated soil treatment machines (that is, the insolubilization treatment device 1A and the solidification treatment device 1B) are mounted on the base frames 2A and 2B to form one unit. Each of the insolubilizing apparatus 1A and the solidifying apparatus 1B has a necessary device and a power unit thereof, and is configured to be able to perform the first and second steps independently. As described above, the method for treating fluorine-contaminated soil according to the present invention can insolubilize fluorine-contaminated soil only in the first and second two steps. By using only two devices of the solidification treatment device 1B for performing the two processes, the treatment system for fluorine-contaminated soil can be made compact.
[0054]
In addition, since it can be transported and transported by at least the unit of the insolubilization treatment device 1A and the solidification treatment device 1B, some necessary devices such as a conveyer, a mixing device, an additive supply device, and the like are provisionally appropriately procured. Compared to the system constructed by arranging the equipment, it is easier to carry in and out the work site, and work such as assembly and disassembly is greatly reduced. It can be sufficiently secured. Also, even in the case where the site itself is relatively narrow and must perform leveling work in parallel with the construction work, the contaminated soil treatment machine in the present embodiment can be easily transported by, for example, a crane or a trailer, The installation position can be appropriately changed. In the present embodiment, a processing system for fluorine-contaminated soil can be constructed in two steps, so that the system can be made compact in this way, and as a result, fluorine-contaminated soil can be quickly removed in a work site. The effect of the present invention of being able to perform the processing can be made more remarkable.
[0055]
(4) Prevention of scattering of contaminated soil, continuity of treatment, effective use of space
Since the treatment of fluorine-contaminated soil is regarded as the treatment for insolubilizing contaminants, it is necessary to avoid spilling and scattering of fluorine-contaminated soil during treatment. If, as described above, merely constructing a fluorine-contaminated soil treatment system by arranging necessary devices as appropriate, for example, when the fluorine-contaminated soil is conveyed to a mixing device, there are places where spillage of the fluorine-contaminated soil may occur. There are many. On the other hand, in the present embodiment, since a series of devices are unitized, the probability of spillage of the fluorine-contaminated soil between the devices during operation is low, and because of the compact configuration, the fluorine-contaminated soil It is also easy to cover the soil transport path at the required places, and it is possible to easily prevent scattering of the fluorine-contaminated soil during processing.
[0056]
Furthermore, in a system in which necessary devices are simply arranged as appropriate, such as when loading and unloading the system, each device must be individually loaded and unloaded on a trailer or the like. Therefore, when transporting between sites, if the fluorine-contaminated soil remains in each device loaded on the trailer, the possibility that the fluorine-contaminated soil spills off at the site after transport increases when each device is unloaded. . On the other hand, in the present embodiment, during transportation, the trailer can be loaded and unloaded to each unit such as the insolubilizing apparatus 1A, the solidifying apparatus 1B, etc. The possibility can be reduced accordingly. The same applies when the installation position is moved within the same work site.
[0057]
In addition, the contaminated soil treatment system of the present embodiment is compact and unitized, and can be easily moved in a work site. Can be moved relatively easily. Therefore, by moving the system to the excavation site of the fluorine-contaminated soil, it is not necessary to transport the fluorine-contaminated soil from the excavation site to the treatment system, but can be directly supplied to the treatment system, and the contaminated soil is transported to the treatment system. In addition, there is an advantage that the scattering of the fluorine-contaminated soil can be prevented, and a series of operations of excavation and insolubilization of the fluorine-contaminated soil can be continuously performed.
[0058]
Furthermore, because it is compact and unitized, it does not take up installation space even in a relatively small work site, and it is possible to effectively use the narrow work space.For example, fluorine elution in the soil in an operating factory Even if it is found that the amount exceeds the reference value and this is voluntarily insolubilized, the minimum amount of space can be used effectively and the fluorine-contaminated soil can be used without interrupting the production activities of the factory. Can be rapidly performed.
[0059]
Embodiment 1
The inventors of the present application prepared 1 kg of soil with 50% red soil and 50% sand by weight and mixed with fluorine to prepare a simulated test soil having a fluorine elution amount of 1.1 mg / L. The measurement results of the elution amount of fluorine in this example are all based on the official method described above. Then, for 1 kg of the simulated test soil prepared in the same manner, first, as the above-mentioned first step, 50 g of an aqueous solution of 10 g of calcium chloride and 5 g of aluminum sulfate were mixed. (Blast furnace B cement) 50 g was mixed. Mixing in these first and second steps was performed using a 3 L capacity pan mixer. As a result, a result was obtained in which the elution amount of fluorine by the official method satisfied the soil environmental standard of 0.3 mg / L (0.8 mg / L). The hydrogen ion concentration of the simulation test soil after the treatment at this time was pH 5.9.
[0060]
Embodiment 2
A simulated test soil was prepared in the same manner as in Example 1, and the result of mixing 1 kg of the simulated test soil with 50 mL of an aqueous solution in which 10 g of calcium chloride was dissolved and 5 g of aluminum sulfate (that is, only the first step was performed) As a result, the elution amount of fluorine by the official method was 1.1 mg / L, which slightly exceeded the soil environmental standard value (0.8 mg / L). On the other hand, for 1 kg of the simulated test soil, as a first step, a 50 mL aqueous solution in which 10 g of calcium chloride was dissolved and 5 g of aluminum sulfate were mixed, and as a second step, 50 g of an alkaline solidified material was mixed. The amount of fluorine eluted by the official method was reduced to 0.6 mg / L, and the result that cleared the soil environmental standard value (0.8 mg / L) was obtained. At this time, the measured value of the hydrogen ion concentration after the treatment was pH 5.8. In this way, considering the addition of the solidifying material, by setting the hydrogen ion concentration of the soil after performing the first and second steps to about pH 6, stabilization of the insolubilized state and securing of soil strength are possible. It was confirmed that the insolubilized state of fluorine itself was improved.
[0061]
FIG. 7 is a side view showing the entire structure of another example of the contaminated soil treatment system used in the method for treating contaminated soil of the present invention. In FIG. 7, the pump unit 28 is not shown for the purpose of preventing complexity. In FIG. 7, reference numeral 100 denotes a hydraulic excavator as a fluorine-contaminated soil supply means for feeding excavated fluorine-contaminated soil, 200 a self-propelled insolubilizing machine for insolubilizing the received fluorine-contaminated soil, and 300 a insolubilized mixed material. It is a self-propelled solidification processing machine that solidifies soil.
[0062]
The hydraulic excavator 100 is a self-propelled type, and includes a traveling device 102 having an endless track crawler 101, a revolving body 103 rotatably provided on an upper portion of the traveling device 102, and a revolving body 103 which is rotatable. Connected articulated front device (= boom 104 whose base end is pivotally supported by revolving body 103, arm 105 rotatably connected to boom 104, and rotatably connected to arm 105 (Which is constituted by a bucket 106 configured). With such a configuration, the excavator 100 scoops the contaminated fluorine-contaminated soil into the bucket 106 and supplies the bucket to the self-propelled insolubilization machine 200.
[0063]
The main configuration of the self-propelled insolubilization processing machine 200 and the self-propelled solidification processing machine 300 is the same as that of the above-described insolubilization processing apparatus 1A and solidification processing apparatus 1B (both refer to FIG. 2). The same parts as those in the insolubilizing apparatus 1A and the solidifying apparatus 1B are denoted by the same reference numerals, and description thereof will be omitted. The self-propelled insolubilization processing machine 200 and the self-propelled solidification processing machine 300 generally include a traveling device 45 below the main body frame 10 of the insolubilization device 1A and the solidification processing device 1B, respectively. The traveling device 45 includes a track frame 46 continuously provided below the main body frame 10, a driven wheel (idler) 47 and a driving wheel 48 provided at both ends of the track frame 46, and the driven wheel 47 and the driving wheel 48. It is composed of a crawler crawler belt 49 looped around and a drive device 50 directly connected to the drive wheels 48. Thereby, the self-propelled insolubilizing machine 200 and the insolubilizing machine 300 have the same functions as the insolubilizing apparatus 1A and the solidifying apparatus 1B, respectively, and are capable of running by themselves.
[0064]
In the contaminated soil treatment system of the present embodiment having the above-described configuration, first, the contaminated fluorine contaminated soil is excavated by the excavator 100 and is introduced into the sieve device 3 of the self-propelled insolubilization processing machine 200. The fluorine-contaminated soil introduced into the sieving device 3 is guided to the hopper 4, stirred by the arch breaker 18 (see FIG. 3) while being hydrated by the above-mentioned water supply line 32 aa (see FIG. 1), and mixed through the transport conveyor 5. It is introduced into the device 7. At this time, additives (aluminum salt solution and calcium salt solution) are supplied to the fluorine-contaminated soil introduced into the mixing device 7 by the additive supply device 6. Then, the fluorine-contaminated soil and the additive are uniformly mixed in the mixing device 7 and supplied to the self-propelled solidification processing machine 300 via the discharge conveyor 8 as the mixed soil.
[0065]
In the self-propelled solidification processing machine 300, the mixed soil received by the hopper 4 is added with the solidifying material from the powder supply device 39 while being transported by the transport conveyor 5, and is introduced into the mixing device 7. The treated soil and the solidified material introduced into the mixing device 7 are uniformly stirred and mixed by a paddle mixer, and are discharged onto a discharge conveyor 8. Then, the treated soil on the discharge conveyor 8 is finally discharged out of the machine, collected at, for example, a predetermined collecting position, and cured for a predetermined period.
[0066]
Also in the present embodiment, the fluorine-contaminated soil can be insolubilized by the first step using the self-propelled insolubilization processing machine 200 and the second step using the self-propelled solidification processing machine 300, and thus the same as above. To get the effect. Further, in this embodiment, in particular, the excavator 100, the self-propelled insolubilizing machine 200, and the self-propelled solidifying machine 300 each include a traveling device, and are each loaded and unloaded on a transportation means such as a trailer, or on-site. Since the movement can be performed on its own, it is possible to more easily and quickly carry in and out of the work site and to move within the work site. Therefore, the fluorine-contaminated soil can be processed more quickly in the work site, the space can be effectively used, and the degree of freedom of the system layout can be improved.
[0067]
In this embodiment, the hydraulic excavator 100 is used as a means for supplying the fluorine-contaminated soil to the self-propelled insolubilizing machine 200, but may be a belt conveyor, a screw conveyor, or the like. In this case, it is more preferable that a storage means such as a hopper is provided to store a predetermined amount of fluorine-contaminated soil and that the fluorine-contaminated soil can be continuously transported. In FIG. 7, the hydraulic excavator 100 and the self-propelled insolubilization processing machine 200 are arranged on the embankment in order to directly supply the processed soil from the self-propelled insolubilization processing machine 200 to the self-propelled solidification processing machine 300. Although the self-propelled solidification processing machine 300 is arranged one step lower, for example, by arranging the self-propelled solidification processing machine 300 one size smaller than the self-propelled insolubilization processing machine 200, Contaminated soil treatment systems can be installed at the level.
[0068]
FIG. 8 is a side view showing the overall structure of still another example of the contaminated soil treatment system used in the method for treating contaminated soil of the present invention. In FIG. 8, the pump unit 28 is not shown for the purpose of preventing complexity, and the same parts as those in FIG. In FIG. 8, reference numeral 250 denotes a mixed soil supply device. The mixed soil supply device 250 includes a hopper 251 serving as a storage container for receiving and temporarily storing the processed soil from the self-propelled insolubilization processing machine 200, and a processing device in the hopper 251. A conveyor 252 is provided as supply means for supplying the soil to the self-propelled solidification processing machine 300. The hopper 251 has almost the same configuration as the hopper 4 and includes an arch breaker 253. Reference numeral 254 denotes a support member for supporting the conveyor 252. In the present embodiment, the mixed soil supply device 250 is a stationary type facility, but instead of the support member 254, a lower portion of the conveyor 252 is used as a vehicle (traveling device). The known self-propelled conveyor supported by the above may be provided with a hopper 251 with an arch breaker 253. This embodiment is the same as the contaminated soil treatment system shown in FIG. 7 except that the mixed soil supply device 250 is newly disposed between the self-propelled insolubilization processing machine 200 and the self-propelled solidification processing machine 300. It is.
[0069]
In the present embodiment, the same effect as described above is obtained by the addition of the mixed soil supply device 250, and the treated soil from the self-propelled insolubilization processing machine 200 is further agitated so that the fluorine-contaminated soil and the additive are made more uniform. The insolubilization reaction can be further promoted. In addition, the mixed soil in which the fluorine has been insolubilized in the first step is temporarily stored in the hopper 251 to secure the residence time, so that the reaction is promoted or secured, and then the self-propelled solidification is performed. Since the processing can be supplied to the processing machine 300, the processing can be performed more reliably.
[0070]
In this embodiment, the conveyor 252 is a belt conveyor, but may be a screw conveyor or the like. Further, even if the mixed soil supply device 251 is not a conveyor device with a hopper 251, a simple storage container (for example, the hopper 251 may be installed alone) may be used as the self-propelled insolubilizing machine 200 and the self-propelled solidification machine. The hydraulic excavator 100 (either the same one or a separately prepared one) may be provided as a means for supplying the treated soil to the self-propelled solidification processing machine 300 between the two.
[0071]
Further, in the present embodiment, the mixed soil supply device 250 has the hopper 251 provided with the arch breaker 253, but the hopper 251 does not necessarily require the arch breaker 253 as long as the residence time is secured. When the residence time is secured in this way, in each of the above-described embodiments, the residence time may be secured by adjusting the operation state of the mixing device 7. For example, it is conceivable to simply reduce the driving speed of the paddle mixer of the mixing device 7 appropriately, or to secure the residence time in the mixing device 7 by appropriately rotating the paddle mixer forward / reverse and feeding back the treated soil appropriately. You can also. Further, an appropriate number of paddles among a large number of paddles provided in the paddle mixer are mounted at an angle so as to reversely feed the treated soil, a weir is provided near the outlet of the mixing device 7, or the outlet opening area is reduced. For example, the mixing device 7 may be appropriately configured. Further, in a place where the processing amount is relatively small, it is also possible to perform batch processing without performing continuous processing and to appropriately cure, or to close the outlet (not shown) of the mixing device 7 to further sufficiently stir and mix. it can. In these cases, a similar effect is obtained.
[0072]
In each of the embodiments described above, the additive used in the insolubilization apparatus 1A is aluminum sulfate: Al. ₂ (SO ₄ ) ₃ Aqueous solution and calcium chloride: CaCl ₂ However, the present invention is not limited to this. For example, in an aqueous solution of aluminum sulfate, another aluminum salt, for example, aluminum chloride: AlCl ₃ , Aluminum nitrate: Al (NO ₃ ) ₃ , Aluminum silicate: Al ₂ SiO ₅ , Aluminum hydroxide: Al (OH) ₃ , Poly aluminum chloride (PAC): [Al ₂ (OH) nCl ₆ -N] m or an aqueous solution of an iron salt may be substituted. In addition, another calcium salt, for example, quicklime (calcium oxide): CaO, slaked lime (calcium hydroxide): Ca (OH) is added to an aqueous solution of calcium chloride. ₂ , Calcium nitrate: Ca (NO ₃ ) ₂ , Calcium carbonate: CaCO ₃ , Calcium sulfate: CaSO ₄ , Calcium hypophosphite: CaPHO ₃ ・ H ₂ An aqueous solution such as O may be substituted. Further, the solidifying material used in the solidification treatment apparatus 1B is, for example, any of solidifying materials having a very low pH such as blast furnace cement, cement-type solidifying material, cement-lime composite-type solidifying material, lime-type solidifying material (or the like). Is preferably used.
[0073]
Further, in the above, an example in which an additive such as an aluminum salt or a calcium salt is added to the fluorine-contaminated soil in an aqueous solution state has been described.However, depending on the water content of the fluorine-contaminated soil, one or both of them are in a powder state. It may be added. Even if the water content of the fluorine-contaminated soil is low, the water content of the fluorine-contaminated soil can be adjusted by supplying water from the water supply line 32aa, so that a series of treatments are performed by adding both aluminum salt and calcium salt in a powder state. It is also possible to do. When these aluminum salts or calcium salts are added in powder form, the aluminum salts or calcium salts are supplied by the powder supply device 39 which is not particularly used in the insolubilizing apparatus 1A or the self-propelled insolubilizing machine 200. be able to. When both the aluminum salt and the calcium salt are added as a powder, both may be mixed in advance, and the powder obtained by mixing the aluminum salt and the calcium salt may be supplied by the powder supply device 39 as one type of additive. It is possible.
[0074]
Further, in the above, the mixing process in the first and second steps is performed using the mixing device 7 having the paddle mixer, but the mixing process in the first and second processes is not necessarily performed in both processes. In one or both of the steps, for example, another type of mixing device such as a screw mixer may be used as the stirring means, or the mixing may be performed manually as long as uniformity of the stirring and mixing can be ensured.
[0075]
Further, in the above description, the traveling devices 45 and 102 are of the so-called crawler type provided with the crawler tracks 49 and 101, but are not limited thereto, and may be so-called wheel-type traveling devices. Furthermore, since the basic object of the present invention is to reduce the number of processes, the traveling device 45 may be omitted from the self-propelled insolubilizing machine 200 and the self-propelled solidifying machine 300 from this viewpoint. Further, the insolubilizing apparatus 1A, the self-propelled insolubilizing machine 200, and the like are provided with the sieving apparatus 3 and the tilt 17 but are not necessarily required. The device 3 and the tilt 17 may be provided. Further, the mixing device 7 is of a paddle type. However, the mixing device is not limited to the paddle type. For example, a mixing device provided with another stirring means such as a screw mixer may be used. In these cases, a similar effect is obtained.
[0076]
【The invention's effect】
According to the present invention, the fluorine-contaminated soil is excreted in only two steps, that is, the first step of mixing the excavated fluorine-contaminated soil with the aluminum salt and the calcium salt, and the second step of mixing the solidified material. Since the insolubilization treatment can be performed, the fluorine-contaminated soil can be quickly and sufficiently insolubilized, and the stability at the time of backfilling can be improved.
[Brief description of the drawings]
FIG. 1 is a block diagram showing a series of processing steps of a contaminated soil treatment system used in an embodiment of the contaminated soil treatment method of the present invention.
FIG. 2 is a side view showing the entire structure of an example of a contaminated soil treatment system used in the method for treating contaminated soil of the present invention.
FIG. 3 is a side view showing a detailed structure near a sieve device and a hopper provided in an example of a contaminated soil treatment system used in the method for treating contaminated soil according to the present invention.
FIG. 4 is a diagram showing a detailed structure near a downstream side of a conveyor provided in an example of a contaminated soil treatment system used in the method for treating contaminated soil of the present invention.
FIG. 5 is a diagram illustrating a structure of a supply pipe provided in an example of a contaminated soil treatment system used in the method for treating contaminated soil according to the present invention.
FIG. 6 is a graph showing the relationship between the pH of soil after the insolubilization treatment and the elution amount of fluorine.
FIG. 7 is a side view showing the overall structure of another example of the contaminated soil treatment system used in the method for treating contaminated soil of the present invention.
FIG. 8 is a side view showing the overall structure of still another example of the contaminated soil treatment system used in the method for treating contaminated soil according to the present invention.
[Explanation of symbols]
1A Insolubilization equipment (contaminated soil treatment machine)
1B Solidification treatment equipment (contaminated soil treatment machine)
4 Hopper
6 Additive supply device
7. Mixing device (first mixing device, second mixing device)
8. Discharge conveyor (discharge means)
39 Powder supply device (solidified material supply device)
45 Traveling device (traveling means)
200 Self-propelled insolubilization machine (contaminated soil treatment machine)
300 Self-propelled solidification machine (contaminated soil treatment machine)

Claims (9)

A first step of stirring and mixing the excavated fluorine-contaminated soil with aluminum salts and calcium salts;
A second step of mixing and mixing the fluorine-contaminated soil, aluminum salt, and calcium salt mixed together in the first step together with the solidifying material, and mixing. A first step of mixing the excavated fluorine-contaminated soil with an aluminum salt and a calcium salt to insolubilize the fluorine in the fluorine-contaminated soil by the interaction between the insolubilization by the calcium salt and the adsorption by the aluminum salt;
A second step of stabilizing properties and adjusting pH by mixing and mixing the fluorine-contaminated soil, aluminum salt and calcium salt mixed soil in the first step with a solidifying material. A method for treating contaminated soil, comprising: 3. The method according to claim 1, wherein a mixing device having a stirring means is used for the mixing in at least one of the first and second steps. The method according to any one of claims 1 to 3, wherein the solidified material is any of a cement-based solidified material, a cement-lime composite-based solidified material, and a lime-based solidified material. Soil treatment method. A first mixing device that receives the excavated fluorine-contaminated soil, and agitates and mixes with the aluminum salt and the calcium salt;
A contaminated soil treatment system comprising: a second mixing device for mixing and mixing the fluorine-contaminated soil, aluminum salt, and calcium salt discharged from the first mixing device together with a solidifying material. . A hopper for receiving the excavated fluorine-contaminated soil, an additive supply device for supplying aluminum salt and calcium salt to the fluorine-contaminated soil, and a mixing device for stirring and mixing the fluorine-contaminated soil with the aluminum salt and calcium salt by built-in stirring means. , And a self-propelled insolubilizing machine having a discharging means for discharging the mixed soil from the mixing device outside the machine,
A hopper for receiving the mixed soil supplied from the self-propelled insolubilizing machine, a solidification material supply device for supplying the solidified material to the mixed soil, and a mixing device for stirring and mixing the mixed soil with the solidified material by a built-in stirring means. A contaminated soil treatment system, comprising: a device; and a self-propelled solidification treatment machine having a discharge means for discharging treated soil from the mixing device to the outside of the machine. A hopper to receive the excavated fluorine-contaminated soil,
An additive supply device for supplying an aluminum salt and a calcium salt to the fluorine-contaminated soil,
A mixing device for stirring and mixing the fluorine-contaminated soil with aluminum salts and calcium salts by a built-in stirring means,
Discharging means for discharging the mixed soil from the mixing device to the outside of the machine. A hopper for receiving the mixed soil obtained by mixing the fluorine-contaminated soil, aluminum salt, and calcium salt;
A solidifying material supply device for supplying a solidifying material to the mixed soil,
A mixing device for stirring and mixing the mixed soil with the solidifying material by a built-in stirring means,
Discharging means for discharging the treated soil from the mixing device to the outside of the machine. The contaminated soil treatment machine according to claim 7 or 8, further comprising a traveling means capable of running by itself.

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