JP2006088110A - Cleaning material for organic chlorine based compound contamination and cleaning method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To make cleaning of VOC contamination ground and reversal of ground strength compatible regardless of a kind of solidifying material added to a metal based reducing agent. <P>SOLUTION: The cleaning material for the organic chlorine based compound contamination is formed by adding a cement based or a lime based solidifying material having pH of 11 or higher or a solidifying material formed by combining these to an iron particulate powder having an average particle diameter of 0.05-0.50 μm and α-Fe content of 30 wt.%-90 wt.%. In the cleaning method, the organic chlorine based compound contamination ground is scavenged, the cleaning material for the organic chlorine based compound contamination is added and mixed to the scavenged soil and this is refilled again in a site or is conveyed to the outside of the site. The organic chlorine based compound contamination ground is not scavenged and the cleaning material for the organic chlorine based compound contamination is delivered and mixed into the organic chlorine based compound contamination ground as a powder or a slurry loaded with water. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a purification material and a purification method for purifying soil and groundwater contaminated with an organic chlorine-based compound (hereinafter referred to as VOC).

  As a method for purifying soil and groundwater contaminated with VOC, there is a method of decomposing and purifying pollutants by mixing a metallic reducing agent such as iron powder with contaminated soil or injecting it into the contaminated soil. (For example, refer to Patent Documents 1, 2, 3, and 4 and Non-Patent Document 1). This method is roughly divided into a method of excavating contaminated soil with a backhoe or an all casing and treating it on the ground, and a method of in-situ treatment (injection or mixing).

However, because the ground in Japan often significantly decreases in strength when disturbed, soils contaminated with VOCs and groundwater are mixed and injected with metal-based reducing agents such as iron powder. When decomposing and purifying the soil, the ground strength after the purification treatment is significantly reduced.
Table 1 shows the uniaxial compressive strength of undisturbed soil (undisturbed soil) and the uniaxial compressive strength immediately after the soil is completely disturbed by a mixer and after one month of standing after the disturbance. From this, it can be seen that the soil is significantly reduced in strength due to disturbance, and that the subsequent strength recovery is far from the previous undisturbed soil strength. For this reason, when contaminated soil is excavated and treated on the ground, a large amount of muddy purified soil will be difficult to treat, and when in-situ treatment is performed using a mixing treatment machine, purification work is performed. In addition to the danger of purification work (eg, the fall of a processing machine or other heavy machinery), the contamination has spread to the boundary of the site, and there is a building near the boundary. If there is an earthen structure, the building or earthen structure may tilt or cause slip failure.

そこで、鉄粉などの金属系還元剤の地盤中への混合・注入に伴う強度低下を生じさせない工法として、ＶＯＣ汚染土用浄化材およびこれを用いた汚染土浄化施工方法（特許文献１）および酸化鉄と石膏系固化材とを用いたＶＯＣ処理技術（非特許文献１）が提案されている。特許文献１、非１特許文献１に開示される技術は、金属系還元剤にｐＨ１１以下であるセメント系の固化材（低アルカリ性）や石膏系の固化材を加えた浄化材（粉体またはスラリー）、およびこれを用いた汚染物質の浄化と汚染地盤の強度回復を両立することを特徴とする工法に関する技術である。

Therefore, as a construction method that does not cause a decrease in strength due to mixing and injection of a metallic reducing agent such as iron powder into the ground, a VOC-contaminated soil purification material and a contaminated soil purification construction method using the same (Patent Document 1) and A VOC processing technique (non-patent document 1) using iron oxide and a gypsum-based solidifying material has been proposed. The technology disclosed in Patent Document 1 and Non-Patent Document 1 is a purification material (powder or slurry) in which a cement-based solidifying material (low alkalinity) or a gypsum-based solidifying material having a pH of 11 or less is added to a metal-based reducing agent. ), And a technique related to a construction method characterized by achieving both purification of pollutants and recovery of the strength of the contaminated ground.

Examples of methods for purifying soil and groundwater contaminated with VOC include, for example, a VOC soil purification method using hydrogen peroxide (see, for example, Patent Document 2), iron powder / iron powder slurry, and a low alkaline solidification material. VOC soil remediation method (for example, see Patent Document 3), Fenton reagent (hydrogen peroxide + iron salt, iron powder) mixed in the contaminated soil in-situ and purified (for example, Patent Document 4) For example).
JP 2004-154744 A Japanese Patent No. 3192020 JP 2000-210683 A JP 2003-251327 A “In-situ treatment method of VOC-contaminated soil using iron oxide and neutral solidifying material” (Study on groundwater / soil contamination and its prevention measures 10th lecture, pp. 505-508, 2004) (May 14-16, Osaka International Exchange Center)

  However, the technique disclosed in Patent Document 1 adds a cement-type solidifying material (low alkalinity) having a pH of 11 or less to a metal-based reducing agent, and purifies and recovers strength by in-situ mixing, or excavating and mixing the Although it is a method of purifying and recovering strength by backfilling or carrying out of the site, it is difficult to reduce the concentration of contaminated soil to an environmental standard value or less when using a solidified material having a pH of 11 or higher. The stabilizing material for securing is limited to a low alkaline solidified material having a pH of 11 or less.

On the other hand, the technology disclosed in Non-Patent Document 1 is a method for purifying and restoring strength by mixing and stirring a gypsum-based solidifying material and a metal-based reducing agent in-situ with a deep mixing ground improvement machine. The metal reducing agent is limited to iron oxide, and the solidifying material is limited to gypsum solidifying material.
As described above, the past patents and techniques are based on the purification of contaminants and the contamination of the soil by using a purification agent in which a cement-based solidifying material (low alkalinity) or a gypsum-based solidifying material having a pH of 11 or less is added to a metal reducing agent. Although it is a construction method that achieves both strength recovery, there are limited stabilizers applicable for ground strength recovery.

In general, it is considered that the VOC purification principle using a metal-based reducing agent is based on the following reaction formula (exhibition: Journal of Groundwater Society Vol. 42, No. 1, pp27-pp45, 2000).
CHCl ₂ · CHCl ₂ + 4Fe + 4H ₂ O → CH ₃ · CH ₃ + 4Fe ²⁺ + 4Cl ⁻ + 4OH ⁻
C ₂ HCl ₃ + 3Fe + 3H ₂ O → C ₂ H ₄ + 3Fe ²⁺ + 3Cl ⁻ + 3OH ⁻
However, ferrous ions (Fe ²⁺ ) generated as a result of the reaction of the metal reducing agent become iron hydroxide. Under high alkaline conditions, the solubility of iron hydroxide is extremely small, so that an insoluble film is formed on the surface of the iron particles, thereby preventing contact with the object to be purified, and as a result, the purification effect is significantly reduced. Therefore, in order to prevent the ground strength from being lowered due to the injection / mixing of the metal-based reducing agent, a highly alkaline solidifying material cannot be used, and a low alkaline solidifying material or a neutral solidifying material must be used. ing.

  Fig. 1 and Fig. 2 show the amount of solidification material added, uniaxial compressive strength, and water content when alluvial clay is solidified with cement-type solidification materials (high alkalinity and low-alkaliness) and gypsum-type (neutral) solidification materials The ratio and uniaxial compressive strength are shown. In addition, B-type blast furnace cement is used as the highly alkaline cement-based solidification material, magnesia-based cement mainly composed of magnesium oxide as the low-alkaline cement-based solidified material, and solidified material mainly composed of anhydrous gypsum as the plaster-based solidified material. Yes.

  As a result, in the case of low alkaline cement-based solidified material and gypsum-based solidified material, the amount added is significantly higher than that of high alkaline cement-based solidified material, and the moisture content of the target soil is high. Then, it can be seen that the amount added is remarkably increased. In addition, the unit price of the low alkaline cement-based solidified material and gypsum-based solidified material is more than several times that of the high alkaline cement-based solidified material. Will use a large amount of expensive materials.

In Patent Document 2, it is an in-situ oxidation process by injection of Fenton reagent or jet stirring, and it is difficult to reduce high concentration contamination to an environmental standard value or less in a short period of time, and jet stirring was performed. There is a problem that the place becomes muddy and the ground strength is extremely lowered.
Further, in Patent Document 3, since hydrogen peroxide and permanganate are added directly to the soil, for example, there is a problem that hydrogen peroxide and permanganate are not uniform, or soil of a predetermined depth. In this case, there was a problem that sufficient purification could not be performed.

  Further, in Patent Document 4, the Fenton reagent is mixed and purified in situ, but as in Patent Document 2, it is difficult to reduce high-concentration contamination to an environmental reference value or less in a short period of time. In addition, in the specification of Patent Document 4, there is a description that “iron powder is mixed and stirred, and then hydrogen peroxide is added and mixed”. In this case, the iron powder is used as a reagent for the Fenton reagent. Therefore, reductive decomposition of VOC is not aimed. In the order of iron powder → hydrogen peroxide, the reducing ability of iron powder is consumed by hydrogen peroxide, and long-term and reliable decomposition of VOC cannot occur.

  The present invention has been made to solve such conventional problems, and its purpose is to purify VOC-contaminated ground and restore ground strength regardless of the type of solidifying material added to the metal-based reducing agent. An object of the present invention is to provide a purification material and a purification method capable of achieving both.

The invention according to claim 1 is an iron fine particle powder having an average particle diameter of 0.05 to 0.50 μm and an α-Fe content of 30 wt% to 90 wt%. It is characterized by adding a lime-based material or a combination of these materials.
The invention according to claim 2 excavates the chlorinated compound-contaminated ground, adds the chlorinated compound-contaminated purification material according to claim 1 to the excavated soil, mixes it, and refills it in the site or It is characterized by being taken out of the field.

  The invention according to claim 3 does not excavate the organic chlorine-based compound-contaminated ground, and the organic chlorine-based compound-contaminated purification material according to claim 1 as a powder or as a slurry to which water is added. It is characterized by being discharged and mixed in.

According to the present invention, contaminated soil can be decomposed to an environmental standard value or less even under high alkaline conditions. By using iron fine particle powder as a metal reducing agent, contaminated soil about 100 times the environmental standard value can be decomposed to below the environmental standard value even when used in combination with a cement-based solidifying material (high alkalinity).
According to the present invention, it is possible to recover a decrease in ground strength due to direct mixing with soil. When in-situ processing is performed using a mixed processing machine, the entire area where purification work has been performed becomes ground with significantly reduced strength, and construction heavy machinery falls, adjacent buildings and earth structures tilt or slip. However, it is possible to recover the ground strength immediately after construction by using a solidifying material, and to realize a state that does not affect future land use.

  According to the present invention, it is possible to purify the vicinity of the mixing site. Since the iron fine particle powder maintains the decomposition effect for a long time, the decomposition of the contaminants remaining not only at the mixing site but also around the mixing site is promoted.

Hereinafter, the present invention will be described with reference to embodiments.
(1) Purifier for VOC contamination using iron fine particle powder In this embodiment, in order to increase the activity of the metal reducing agent in order to reduce the reaction inhibition of the metal reducing agent in a highly alkaline environment, Solidified material (cement or lime or a combination thereof) is added to the iron fine particle powder having a particle size of 0.05 to 0.50 μm and an α-Fe content of 30 to 90% by weight. It was. The iron fine particle powder having an average particle diameter of 0.05 to 0.50 μm and an α-Fe content of 30 wt% to 90 wt% has a content of pure iron (α-Fe) as a main component of the reduction reaction. Since the particle size is small and the number of active sites required for the reduction reaction is large at the initial stage of mixing, the influence of reaction inhibition due to the formation of iron hydroxide film can be ignored, and the VOC can be purified.

The VOC contamination purification material obtained by adding a solidifying material to this iron fine particle powder has a pH value of the iron fine particle powder having an α-Fe content of 30 wt% to 90 wt% and an average particle size of 0.05 to 0.50 μm. Is formed by adding 11 or more cement-based or lime-based or a solidified material (high alkalinity) in combination thereof.
Here, an iron fine particle powder having an average particle diameter of 0.05 to 0.50 μm and an α-Fe content of 30 to 90% by weight will be described.

The average particle size of iron powder is 50-100 μm (10-150 μm) on average, the particle size of fine iron powder is 0.6 μm on average, and the α-Fe content is 25% by weight. When combined with alkaline ordinary cement, inhibition of the reaction was confirmed.
However, the ultrafine iron powder used in the present embodiment has an average particle size of 0.07 μm (0.05 to 0.5 μm) and an α-Fe content of 30% to 90% by weight. No reaction inhibition was confirmed even in a highly alkaline environment.

Since the reductive decomposition reaction of iron depends on the reaction rate (α-Fe content) and the specific surface area (particle diameter), a large reaction rate is required to prevent reaction inhibition in a highly alkaline environment. The ultrafine iron powder meets this condition.
Next, the basis for the fine iron powder having an average particle size of 0.05 to 0.50 μm and an α-Fe content of 30 to 90% by weight will be described.

In order to increase the specific surface area by making fine particles smaller than the average particle diameter of 0.6 μm of the conventional fine iron powder and to obtain a large reaction rate in the reductive decomposition reaction of iron, the average particle diameter of the iron powder is 0.05 to It was 0.50 μm.
Moreover, it is desirable that the ratio of pure iron is 30% by weight to 90% by weight because the reaction point increases as the purity increases. Therefore, the upper limit is 100% by weight, but is 90% by weight for the following reason. If it is 100% by weight, the production process costs high. Moreover, since the activity is excessively increased and the reaction proceeds during storage and the activity decreases, it is desirable to stabilize the surface as iron oxide.

Moreover, content of iron as a slurry is 5 to 20 weight%. The standard composition is 12.5% pure iron + 12.5% iron oxide + 75% water by weight.
Next, the solidifying material will be described. FIG. 3 shows the classification of the solidified material.
Solidifying materials are roughly classified into cement-based, lime-based, and gypsum-based, and cement-based solidifying materials are classified into high-alkaline cement and low-alkaline cement. High alkaline cements include Portland cement (ordinary Portland cement, early-strength Portland cement, ultra-high-strength Portland cement, moderately hot Portland cement, sulfate-resistant Portland cement, low heat Portland cement, etc.), mixed cement (blast furnace cement, silica cement, Fly ash cement, etc.), special cement (alumina cement, cement solidified material, seawater resistant cement, blast furnace slag-gypsum cement, blast furnace slag-lime cement, high sulfate slag cement, eco cement, etc.) and combinations thereof There is something.

  On the other hand, the low alkaline cement includes magnesia cement and magnesia cement mainly composed of magnesium oxide. Examples of the lime-based solidifying material include slaked lime, quick lime, and dolomite. Examples of the gypsum-based solidifying material include anhydrous gypsum, hemihydrate gypsum, and dihydrate gypsum. Further, as other solidifying materials, there are combinations of cement, lime and gypsum.

In the present invention, high alkalinity having a pH of 11 or higher is referred to as a solidifying material. This is because general cement (Portland cement, blast furnace cement), lime, and the like are mainly composed of calcium oxide (CaO), and thus have a pH of 12 to 13 when formed into a slurry.
Moreover, pH 11 or less is called low alkalinity. This is because magnesia-based cement called low alkali cement is mainly composed of magnesium oxide (MgO), and thus becomes pH = 10 to 11 in a slurry state.
(2) Purification method using purification material for VOC contamination There are the following two purification methods using the purification material for VOC contamination.

1. A construction method in which contaminated ground is excavated, the above-mentioned VOC-contaminating purification material is added to the excavated soil, mixed, and then backfilled within the site or carried out of the site.
2. A construction method in which the VOC-contaminated soil purification material is discharged into the contaminated ground as a powder or water-added slurry without being excavated from the contaminated ground and mixed in situ. In addition, as an in-situ mixing treatment method, the following known methods can be cited.

・ Mechanical stirring type deep mixing method (eg CDM method, TRD method, etc.)
Slurry or powder improvement material is discharged or pumped into the local board, excavation stirring blade (single axis / multi axis) at the tip of rotating shaft, chain type cutting stirrer, cutter type (horizontal multi axis / vertical multi axis) cutting A method of forming an improved product by forcibly stirring and mixing with a stirrer. In some cases, the improved material is discharged at the time of penetration, at the time of withdrawal, or at both the penetration and withdrawal steps.

・ High pressure injection type deep mixing method (eg JSG method)
A slurry-like improvement material is jetted horizontally or crossed as a high-pressure soot fluid (jet jet), and the improvement body is obtained by stirring and mixing the soil and the improvement material while cutting the local board using the energy of the high-pressure jet fluid. A method of forming an improved body by injecting an improved material into an artificial space that has been formed or cut, or by stirring and mixing the soil and the improved material in the ground together with mechanical stirring. It should be noted that the water-air-material injection system, the air-material injection system, the material injection system, and the like are classified according to the injection form and the working pressure.

・ Surface treatment method A powder or slurry-like improved material is sprayed on the local board or discharged into the ground, and mixed with soil by a backhoe or stabilizer (surface improvement machine) to form an improved body.
In this embodiment, in any purification method, the contaminated soil can be decomposed to an environmental standard value or less even under high alkaline conditions. By using iron fine particle powder as a metal reducing agent, even when used in combination with a cement-based solidifying material (high alkalinity), contaminated soil about 100 times the environmental standard value can be decomposed to the environmental standard value or less. Moreover, the ground strength fall accompanying direct mixing with soil can be recovered. When in-situ processing is performed using a mixed processing machine, the entire area where purification work has been performed becomes ground with significantly reduced strength, and construction heavy machinery falls, adjacent buildings and earth structures tilt or slip. However, by using a solidifying material in combination, the ground strength can be recovered immediately after construction, and a state that does not affect future land use can be realized. Moreover, purification around the mixing site can be performed. Since the iron fine particle powder maintains the decomposition effect for a long time, the decomposition of the contaminants remaining not only at the mixing site but also around the mixing site is promoted.

In addition, the soil environment standard value is prescribed | regulated as follows as soil elution amount of an organic chlorine type compound.
Trichlorethylene (PCE) 0.03mg / L
Tetrachloroethylene (TCE) 0.01mg / L
cis-1,2-dichloroethylene (cis-1,2-DCE) 0.04 mg / L

(Indoor experiment with simulated contaminated water)
Confirmation of reductive decomposition inhibition effect by combined use of solidification material Experimental method Ion exchange water: 83.5mL
Solidification material: Low alkaline cement (magnesia cement)
High alkaline cement (Type B blast furnace cement)
5g each (5% for 100mL water)
Metal reducing agent: Slurry iron fine particle powder (an iron fine particle powder slurry having an average particle diameter of 0.05 to 0.50 μm and an α-Fe content of 30% by weight, hereinafter referred to as a highly active iron powder slurry. )
Conventional iron powder slurry (iron powder slurry with an average of 0.6 μm and α-Fe content of 25% by weight)
20g each (5% iron particles for 100mL water)
Pollutant: Trichlorethylene (TCE) 10mg / L (100 times the environmental standard value)
Mixing method: Solidified material → water → iron powder slurry → TCE in the order of 100 mL screw mouth glass bottle, sealed, and then shaken and stirred.

Concentration measurement: 1 mL is collected after a predetermined period, and residual TCE is measured.
2. Experimental Results The relationship between the elapsed days and the TCE elution concentration is shown in FIGS. 4 and 5 separately for the case where the highly active iron powder slurry is used and the case where the conventional iron powder slurry is used.
When a highly active iron powder slurry is used as the metal reducing agent, as shown in FIG. 4, regardless of the presence or absence of the addition of a solidifying material, in all cases, a decrease in concentration to an environmental standard value or less is observed after 3 days, No inhibition of reductive decomposition by addition of Type B blast furnace cement was confirmed.

On the other hand, when a conventional iron powder slurry is used as the metal reducing agent, as shown in FIG. 5, the case where the magnesia-based cement was added showed a decrease in concentration to an environmental standard value or less after 6 days. In the case where the B-type blast furnace cement was added, no concentration reduction was observed.
From the above, it was confirmed that a highly alkaline cement could be applied if iron fine particle powder was adopted as the metal reducing agent.

(Indoor experiment with simulated contaminated soil)
(1) Confirmation of reductive decomposition inhibition effect by combined use of solidifying material Experimental method Sample soil: Alluvial clay soil (ρs = 2.519 g / cm ³ , w = 87.0%,
wL = 63.5%, wp = 28.9%, Ip = 34.6)
Volcanic ash clay (ρs = 2.509g / cm ³ , w = 110.0%,
wL = 142.2%, wp = 61.4%, Ip = 80.8)
Solidified material: Ordinary Portland cement (N cement)
Class B blast furnace cement (BB cement)
Cement-based solidifier for volcanic ash clay (C cement)
30kg / m ³ each
Metal reducing agent: Slurry iron fine particle powder (highly active iron powder slurry) 10 kg / m ³
Pollutant: Trichlorethylene (TCE) 10g / kg
Tetrachloroethylene (PCE) 2g / kg
Mixing method: 1) Create high-concentration contaminated soil (TCE 10 g / kg, PCE 2 g / kg)
After mixing the contaminated soil + clean soil with a mixer for 2 minutes,
Rally (highly active iron powder slurry + solidifying material + water) is mixed for 2 minutes.

2) Collect the soil immediately after mixing and conduct the PCE and TCE dissolution test, and use this as the initial value.
3) Fill the remaining mixed soil into a 500 mL glass bottle and seal.
Concentration measurement: After a predetermined period, the soil is collected and a PCE and TCE dissolution test is performed.
2. Experimental results 1) Alluvial clay soil The relationship between elapsed days and PCE elution concentration, and elapsed days and TCE elution concentration is shown in FIGS.

When a highly active iron powder slurry is used as the metal reducing agent, TCE will be less than the environmental standard value after 7 days and PCE will be 21 days later, regardless of the presence of highly alkaline cements such as N cement and BB cement. The concentration was reduced to below the environmental standard value. Eventually, a reduction in concentration of about 1/1000 of the initial concentration was observed with TCE and about 1/100 of the initial concentration with PCE, and inhibition to reductive decomposition due to the addition of highly alkaline cement was not confirmed.
2) Volcanic ash clay The relationship between elapsed days and PCE elution concentration, and elapsed days and TCE elution concentration is shown in FIGS.

When high-activity iron powder slurry is used as the metal reducing agent, TCE is less than the environmental standard value after 3 days, and PCE is the environmental standard value after 14 days, regardless of the presence of highly alkaline cement such as C cement. The density reduction to the following (about 1/100 to 1/500 of the initial density) was observed. Eventually, a decrease in concentration of about 1/400 of the initial concentration was observed with TCE and about 1/1000 of the initial concentration with PCE, and inhibition to reductive decomposition due to the addition of highly alkaline cement was not confirmed.
(2) Confirmation of strength recovery by solidified material Experimental Method Sample Soil: Cohesive soil (ρs = 2.768 g / cm ³ , w = 96.0%,
wL = 72.6%, wp = 32.4%, Ip = 40.2)
Sandy soil (ρs = 2.724 g / cm ³ , w = 11.0%,
Fine grain content 9.7%)
ROHM (ρs = 2.509 g / cm ³ , w = 110.0%,
wL = 142.2%, wp = 61.4%, Ip = 80.8)
Solidified material: Class B blast furnace cement
Magnesia cement Water cement ratio: 80%
Mixing method: 1) Add pre-mixed solidifying material slurry (solidifying material + water) to sample soil and mix for 5 minutes.

2) The mixed soil is packed in 3 layers in a plastic mold of φ3.5cm x h7.0cm and sealed and cured in a constant temperature / humidity chamber at 20 ° C for a specified period.
Strength measurement: After a predetermined period, soil is collected and a uniaxial compression test is performed.
2. Experimental Results FIG. 10 and FIG. 11 show the relationship between the amount of solidified material added and the uniaxial compressive strength at the age of 28 days. Incidentally, the degree to which people walk as the target strength (20kN / m ²⁾ strength of the soil with an intensity of ~ medium with (100kN / m ²⁾ as a guide, taken generally set at 50 kN / m ^2.

When using a B type blast furnace cement solidifying material, as shown in FIG. 10, for cohesive soil 60 kg / m ^3, for sandy soils it can be seen that the target strength 50 kN / m ² obtained by 30kg / m ³ .
On the other hand, when using a magnesia-based cement solidifying material, as shown in FIG. 11, for cohesive soil 60 kg / m ^3, for the sandy soil 50 kg / m ^3, for Kanto loam goals strength 10 kg / m ³ It can be seen that 50 kN / m ² is obtained.

From the above, it was confirmed that the ground strength of about 50 kN / m ² could be recovered after 28 days by using the solidified material together.

It is a graph which shows the solidification material addition amount and uniaxial compressive strength at the time of solidifying the alluvial clay with the cement type solidification material (high alkalinity, low alkalinity) and the gypsum type (neutral) solidification material. It is a graph which shows the water content ratio and uniaxial compressive strength at the time of solidifying the alluvial clay with the cement-type solidification material (high alkalinity, low alkalinity) and the gypsum-type (neutral) solidification material. It is a figure which shows the classification | category of a solidification material. It is a graph which shows the relationship between the elapsed days at the time of using a highly active iron powder slurry, and a TCE elution density | concentration. It is a graph which shows the relationship between the elapsed days at the time of using a conventional type iron powder slurry, and TCE elution density | concentration. It is a graph which shows the relationship between elapsed days and PCE elution concentration about alluvial clay. It is a graph which shows the relationship between elapsed days and a TCE elution density | concentration about alluvial clay. It is a graph which shows the relationship between elapsed days and PCE elution density | concentration about volcanic ash clay. It is a graph which shows the relationship between elapsed days and TCE elution density | concentration about volcanic ash clay. It is a graph which shows the relationship between the addition amount of the solidification material at the time of using B class blast furnace cement for a solidification material, and the uniaxial compressive strength in the age of 28 days. It is a graph which shows the relationship between the addition amount of the solidification material at the time of using a magnesia-type cement for a solidification material, and the uniaxial compressive strength in material age 28 days.

Claims (3)

  Solidification of an iron fine particle powder having an average particle size of 0.05 to 0.50 μm and an α-Fe content of 30% to 90% by weight to a cement or lime system having a pH of 11 or more or a combination thereof. A purification material for organic chlorine-based compound contamination characterized by adding a material.   Excavation of organochlorine compound-contaminated ground, mixing the excavated soil with the purification material for organochlorine compound contamination according to claim 1, and then refilling it in the site or carrying it out of the site To clean up soil contaminated with organic chlorinated compounds.   The organic chlorine-based compound contaminated purification material according to claim 1 is discharged into the organic chlorine-based compound contaminated ground as a powder or as a slurry to which water is added without excavating the organic chlorine-based compound contaminated ground. In-situ purification method for soil contaminated with organic chlorinated compounds.

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