JP2002206090A - Neutral soil-solidifying agent and method of improving ground and the like, and means for preventing elution of heavy metal - Google Patents

Abstract

PROBLEM TO BE SOLVED: To add and mix a neutral solidifying agent comprising magnesium oxide as a main component and such an acidic solidification auxiliary as giving a treated soil pH value of 5 to 9, preferably 5.8 to 8.6, instead of a cement-based solidifying agent containing highly toxic hexavalent chromium ion, thereby providing an improved soil having a remarkably enhanced solidified strength and not liable to cause the pollution of alkali and heavy metals. SOLUTION: This neutral soil-solidifying agent is obtained by mixing 100 pts.wt. of magnesium oxide with 10 to 100 pts.wt. of an acidic solidification auxiliary. The acidic solidification auxiliary comprises one or more acidic solidification auxiliaries selected from aluminum sulfate, aluminum polychloride, ferrous sulfate, ferric chloride, acidic sodium sulfate, sulfamic acid, phosphoric acid, and phosphorus compounds giving aqueous solutions having pH values of <=7.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to the technical field of an improvement method for soil neutral solidifying agent soil and the like, a method for improving mud and sludge, and means for preventing elution of heavy metals and the like from contaminated soil.

[0002]

2. Description of the Related Art Conventional shallow and deep ground improvement methods, mud,
As a solidifying agent for soil improvement that solidifies generated soil generated on site such as a sludge improvement method, a cement-based solidifying agent and a lime-based solidifying agent were injected, mixed and stirred, and used.

Therefore, the improved solidified soil using the above-mentioned solidifying agent has a high alkaline value of PH value of 10 to 12, and the cement-based solidifying agent has a highly toxic hexavalent chromium. It was pointed out that there is a risk of melting into the improved solidified soil.

Further, in a conventional method for improving a shallow or deep ground, a boring machine or a backhoe is used to excavate and then inject a solidifying agent such as a soil cement or a cement solidifying agent or a lime solidifying agent. Alternatively, it was added, and the stirring blade attached to the lower part of the rod was rotated to mix and stir well with the soil, or mixed and solidified to obtain an improved soil.

[0005] Therefore, first, there is a risk that the alkalinity is extremely high, and secondly, highly toxic hexavalent chromium may be dissolved from the solidifying agent, particularly from the cement-based solidifying agent.

Further, in order to solidify muddy soil generated by shield work or foundation work or sludge of high water content residual soil generated from dredging work, it takes a long time by drying in the sun, etc., and requires a vast treatment area. there were.

Further, since the sludge is dehydrated by a dehydrator to form a cake, much time is consumed for dehydration.

Further, as means for purifying contaminated soil conventionally contaminated with heavy metals such as hexavalent chromium, the soil at the location is transported to a predetermined treatment plant to remove contaminants contained in the soil. Injecting and backfilling non-contaminated soil,
Or purify the contaminated soil excavated as described above,
Purification means for backfilling the hole again has been used.
For this reason, there have been problems such as an increase in the cost of the purification treatment.

[0009]

The soil neutralizing agent of the present invention contains magnesium oxide as a main component instead of a cement-based solidifying agent containing highly toxic hexavalent chromium, and further has a PH value of the treated soil. 5-9, preferably 5.8-8.6 A neutral solidifying agent mixed with an acidic solidifying aid is added and mixed to increase the solidifying strength remarkably and safely improve without the risk of alkali and heavy metal contamination. It was earth.

Further, the present invention provides a method for preparing a soil such as a muddy soil in a shallow or deep ground improvement work site, wherein the above-described magnesium oxide is a main component and the PH value of the treated soil is 5-9, preferably 5.8-8. The use of a neutral solidifying agent mixed with an acidic solidifying aid to achieve a solidified strength similar to that described above and a safe improved soil free from alkali and heavy metal contamination. I made it.

[0011] The present invention also provides a muddy soil generated at a shield work or a foundation work site and a sludge generated from a dredging work, instead of the conventional cement-based solidifying agent containing highly toxic hexavalent chromium as a soil conditioner. , Containing magnesium oxide as a main component, and the pH value of the treated soil is 5 to 9, preferably 5.8 to
The use of an acidic solidification aid so as to be within 8.6 significantly increases the solidification strength and provides a safe improved soil free from alkali and heavy metal contamination.

[0012] Further, the present invention provides a method for contaminating heavy metals contained in contaminated soil in a simple manner and at a lower cost than conventional means for purifying contaminated soil. It was developed to prevent heavy metals from re-eluting into the soil of the ground.

[0013]

According to the first aspect of the present invention,
10 to 100% by weight based on 100 parts by weight of magnesium oxide
A soil neutral solidifying agent characterized by mixing an acid hardening aid of the above.

According to a second aspect of the present invention, the acidic solidification aid has a pH value of aluminum sulfate, polyaluminum chloride, ferrous sulfate, ferric chloride, sodium acid sulfate, sulfamic acid, phosphoric acid, and an aqueous solution. 2. The soil neutral solidifying agent according to claim 1, wherein one or two or more kinds of acidic solidifying aids are mixed among 7 or less phosphorus compounds.

According to a third aspect of the present invention, in the case of a high water content improved soil to which the solidifying agent is added, a water absorbing agent is used in combination with the solidifying agent. The soil neutral solidifying agent according to claim 2.

According to a fourth aspect of the present invention, the water-absorbing agent may be one or more of a porous inorganic mineral such as activated carbon, activated clay, sepiolite, silicate earth, zeolite, and silica heme, and guar gum, calcium sulfate, and slag. The soil neutralizing agent according to claim 3, which is used by mixing.

According to a fifth aspect of the present invention, the neutral solidifying agent according to the first, second or third aspect is added to the shallow and deep defective ground or soft ground by 1 to 50% by weight based on the volume of the soil to be treated.
This is a method for improving the ground in a shallow or deep layer, characterized in that the ground is improved by adding or pouring, mixing or stirring to improve the ground.

According to a sixth aspect of the present invention, a neutral solidifying agent according to the first or second or third aspect is added and mixed into mud or sludge by 2% to 100% by weight based on the volume of the soil to be treated. It is a mud and sludge improvement method characterized by reclaiming as soil and using it for land reclamation and road subgrade soil after regeneration.

According to a seventh aspect of the present invention, the contaminated soil contaminated by heavy metal or the like at a predetermined depth is formed into a muddy state, and the muddy contaminated soil is mixed with predetermined water and a predetermined amount of magnesium oxide. A soil solidifying agent containing magnesium as a main component is injected, the solidifying agent is mixed with the soil, the magnesium oxide of the injected solidifying agent reacts to solidify the soil, and the heavy metal is transferred to the adjacent soil. This is a means for preventing elution of heavy metals and the like from contaminated soil, characterized by preventing elution of ash.

The invention according to claim 8 is the means for preventing elution of heavy metals and the like from contaminated soil according to claim 7, wherein the soil solidifying agent mixes the magnesium oxide with water.

According to a ninth aspect of the present invention, the soil solidifying agent is obtained by mixing 10 to 100% by weight of an acid solidifying aid with 100 parts by weight of magnesium oxide. 8. Means for preventing elution of heavy metals from contaminated soil according to 8.

According to a tenth aspect of the present invention, the acidic solidification aid has a pH value of aluminum sulfate, polyaluminum chloride, ferrous sulfate, ferric chloride, sodium acid sulfate, sulfamic acid, phosphoric acid, and an aqueous solution. 10. The phosphorous compound of 7 or less, wherein one or more kinds of acidic solidification aids are mixed.
Means for preventing elution of heavy metals and the like from the contaminated soil described.

The invention according to claim 11 is characterized in that the soil solidifying agent adds ferrous sulfate or ferric chloride for stabilizing the heavy metal. A means for preventing elution of heavy metals or the like from contaminated soil according to claim 8 or claim 9 or claim 10.

According to a twelfth aspect of the present invention, the soil solidifying agent comprises a phosphate compound, ferrous sulfate and ferric chloride alone or as a mixture of two or more acidic solidifying agents. Claim 7 or Claim 8 or Claim 9 or Claim 10
Or a means for preventing elution of heavy metals or the like from contaminated soil according to claim 11.

According to a thirteenth aspect of the present invention, the soil hardening agent comprises an acid hardening agent of magnesium chloride mixed therein. A means for preventing elution of heavy metals from contaminated soil according to claim 11 or 12.

[0026]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The embodiments according to the first to sixth aspects of the present invention are common and will be described together as follows.

The neutral solidifying agent of the present invention is for improving defective ground at a construction site for a shallow or deep ground improvement.

Further, according to the present invention, unlike the conventional solidification method, the mud and sludge generated from the dredging work are mixed with a solidifying agent as described below, and the improved soil having a small alkali value and no risk of heavy metal contamination. I made it.

The solidifying agent of the present invention contains 10 parts by weight of magnesium oxide and 100 parts by weight of a mineral containing magnesium oxide.
It is a soil neutral solidifying agent mixed with し 100% by weight of an acidic solidifying aid.

Further, the acidic solidification aid is selected from the group consisting of aluminum sulfate, polyaluminum chloride, ferrous sulfate, ferric chloride, sodium acid sulfate, sulfamic acid, phosphoric acid, and phosphorus compounds having an aqueous solution having a pH of 7 or less. , Or a mixture of two or more solidifying agents.

In the present invention, when the improved soil has a high water content, a water absorbing agent may be used in combination with the solidifying agent.

As the water-absorbing agent, activated carbon, activated clay, sepiolite, silicate earth, zeolite, porous inorganic minerals such as silica heme, guar gum, calcium sulfate, and slag are used alone or in combination of two or more. .

Further, according to the present invention, as a method for improving a shallow or deep defective ground or a soft ground, the above-mentioned magnesium oxide is used as a main component in a boring which has been subjected to boring using a predetermined machine, etc. Neutral solidifying agent obtained by mixing the solidification aid with 1 to 50 to the volume of the soil to be treated.
It is added or injected by weight and mixed or stirred to solidify. As a result, it was possible to improve the ground with high strength as described below.

[First Embodiment] The following favorable results were obtained when the following improvement was conducted for the following soil coarse particle size distributions at the construction site to be subjected to ground improvement treatment.

As the particle size distribution of the soil, (1) sand content 8.4% (2) silt content 47.6% (3) clay content 44.0%

[0036]含土rate 33.6%, water content 66.4%, substantially uniformly sprayed solidifying agent of the present invention an improved target soil 1 m ³ per 50kg of water content of 197.6% of the high humoral silt, This was dug by a backhoe to a depth of about 50 cm and mixed and stirred, and the following improved results were obtained.

Cone index before improvement → 0 KN / m²  Improved cone index after 7 days → 540.5 KN / m²  PH value of improved soil 8.5

[Second Embodiment] Further, the particle size distribution of the soil is as follows: (1) sand content 17.4% (2) silt content 36.6% (3) clay content 46.0%

Soil content 37%, water content 63%, water content 17
10% from 3m GL3m for improvement of 0.2% organic clay
To 100 m, a solidifying agent was injected at a rate of 100 kg per 1 m ^{3 of the} soil to be improved. As a result, the cone index before improvement → 0 KN / m ²

Improved cone index after 7 days → 952.1KN
/ M²  The PH value of the improved soil was 8.6, and a good improvement result was obtained.

[Third Embodiment] As a pre-process of dehydrating sludge or muddy water generated from dredging work and muddy water seal work with a dewatering machine, the solidifying agent of the present invention was added and the dewatered cake was solidified. An improved soil of index and favorable PH value was obtained. 870% water content as lake sludge
After adding 50 kg of solidifying agent per 1 m ³ of sludge, the cake was dehydrated with a dehydrator (filter press).

Cone index of cake after one day → 1,43
0.1KN / m²  A favorable result of PH value of the cake 8.7 after one day was obtained.

An embodiment of the above-mentioned ground improvement method will be described below.

Reference numeral 1 denotes defective ground, reference numeral 2 denotes a backhoe, and reference numeral 3 denotes an improved soil obtained by adding the solidifying agent of the present invention and obtaining the following equipment.

Reference numeral 4 denotes a rod mounted on the boring machine 5. Reference numeral 6 denotes a swivel for injecting a solidifying agent mounted on the head of the rod 4. Reference numeral 7 denotes a ground, and 8 denotes a stirring blade attached to a lower portion of the rod 4. When the solidifying agent of the present invention is injected and mixed and agitated, the defective ground (mud-like) around the agitating blade 8 becomes a high quality improved soil.

Further, according to the present invention, a mud or sludge generated by dredging work using a predetermined machine or the like contains magnesium oxide as a main component, and a neutral solution obtained by mixing the magnesium with an acid-solidifying aid. The solidifying agent is added in an amount of 2% to 100% based on the volume of the soil to be treated, and further mixed to regenerate as an improved soil. As a result, the PH value is 9 or less,
It can be effectively used as a safe land-building soil free of harmful metals and as a roadbed soil.

FIG. 3 shows a mixing apparatus for regenerating the mud and sludge of the present invention into a high quality improved soil.

Reference numeral 9 denotes a mixing tank in which a motor 1 is provided.
0 at a predetermined position of the shaft 11 which rotates by
Attach. Reference numeral 13 denotes a mud charging hopper, and 14 denotes a hopper for adding a neutral solidifying agent.

A predetermined amount of mud is put into the hopper 13
More specifically, a predetermined amount of the neutral solidifying agent of the present invention is supplied from the hopper 14. The mixture is agitated by the blades 12, and is discharged as solidified improved soil 15.

Reference numeral 16 denotes an injection path of dredged sludge or sealed muddy water generated at the construction site, reference numeral 17 denotes a mixing tank, and reference numeral 18 denotes a solidifying agent injection hopper. 19 is a motor for mixing the injected muddy water and the solidifying agent, 20 is a water pipe for mixing and stirring muddy water, 21 is a driving pump, 22 is a water feeding pipe, 2
3 is a filter press.

The filter press 23 has a built-in filter chamber 24 constituted by a filter cloth 25.

Reference numeral 26 denotes a hydraulic cylinder connected to the filter press 23. Reference numeral 27 denotes a dewatered cake dewatered by the filter press 23, and reference numeral 28 denotes filtered water contained in the muddy water.

Further, since the embodiments according to the seventh to thirteenth aspects are common, they will be described collectively as follows.

The soil hardening agent of the present invention comprises the same or similar components as the neutral hardening agent in the above-mentioned inventions 1 to 6.

According to the present invention, a polluted soil contaminated by heavy metals or the like at a predetermined depth is made muddy by using a boring machine a or the like, and a predetermined amount of water and a predetermined amount of oxidized water are contained in the muddy contaminated soil. Injecting a soil solidifying agent mainly containing magnesium oxide mixed with magnesium, mixing the solidifying agent and the soil, and reacting the injected magnesium oxide of the solidifying agent to solidify the soil, It prevents heavy metals from eluting into adjacent soil.

Further, as the soil hardening agent, a mixture of the magnesium oxide and water is used.

The soil hardening agent is obtained by mixing 10 to 100% by weight of an acid hardening aid with 100 parts by weight of magnesium oxide.

Further, the acidic solidification aid includes aluminum sulfate, polyaluminum chloride, ferrous sulfate, ferric chloride, sodium acid sulfate, sulfamic acid, phosphoric acid, and phosphorus compounds having an aqueous solution having a pH value of 7 or less. , Or a mixture of two or more acidic solidification aids.

The soil hardening agent of the present invention may be added with ferrous sulfate or ferric chloride for stabilizing the heavy metal.

Further, the soil solidifying agent may be a phosphate compound, ferrous sulfate and ferric chloride alone or a mixture of two or more acidic solidifying agents.

The soil hardening agent of the present invention may be a mixture of an acid hardening agent of magnesium chloride. [First
Example]

When the soil solidifying agent of the present invention was mixed with mud-like contaminated soil contaminated with heavy metals at a predetermined depth, the following favorable results were obtained. [As a heavy metal to be measured in the measurement test] (1) Lead 650 mg / kg (for this lead, the environmental standard value is 0.01 mg / l or less) (2) Arsenic 220 〃 (〃 0.01 〃) (3) Selenium 22〃 (〃0.01〃)

When the above soil was mixed with a solidifying agent (compounding ratio is as described below) and an elution measurement test was carried out, the results were as follows.

Solidifying agent 100 kg / m³The place where was mixed
(1) Lead 650 mg / kg → The value became 0.005 mg / l. (2) Arsenic 220 〃 → 0.005 〃 (3) Selenium 22 〃 → 0.005 〃 (4) Uniaxial compressive strength qu (KN / m²) → 21 days 21KN / m²  Good results were obtained as described above.

Further, when 150 kg / m ^{3 of the} solidifying agent was mixed, (1) lead 650 mg / kg → the value became 0.005 mg / l or less. (2) Arsenic 220 〃 → The value became 0.005 mg / l or less. (3) Selenium 22 〃 → The value became 0.005 mg / l or less. (4) uniaxial compressive strength ^{qu (KN / m 2) →} 7 days 22Kn / ^{m 2} above as good results were obtained. (Second embodiment)

A heavy metal having a predetermined depth different from that of the first embodiment.
Measurement of mud-like contaminated soil contaminated by genus
Performed and further mixed with a solidifying agent, as shown below
Good results were obtained. Soil environmental standard Mixing of solidifying agent Value of mixing of solidifying agent 150kg / m³ 200kg / m³  (1) Lead 50mg / kg → 0.01mg / l or less 0.005mg / l 0.005mg / l (2) Hexavalent chromium 45mg / kg → 0.05mg / l or less 0.02mg / l 0.01mg / l 7 days 7 days (3 ) Uniaxial compressive strength qu (KN / m²) 20KN / m² 22KN / m²  With good results.

The solidifying agents mixed as described above were as follows. Magnesium oxide 50% Lime perphosphate 25% Ferrous sulfate 25%

Reference numeral a denotes a boring machine for moving the rod b into the contaminated soil c. This machine a has been used in the past.

As the structure of the rod b, a conventionally known structure is used. The specific configuration is as follows.

Reference numeral 30 denotes a water passage provided with an inlet 31 at an upper stage for injecting ultra-high pressure water, and 32 denotes a compressed air inlet provided at a lower stage of the water passage 30. Communicate with

The means for injecting the soil hardening agent of the present invention is the same as the conventional injection method.

The gist of the invention described in claims 7 to 13 is that
First, as a result of the detection test, the rod b having the above-described structure is caused to enter a formation slightly below a formation in which heavy metal exists. Secondly, the rod b is rotated at a predetermined speed while injecting ultra-high pressure water and compressed air from the rod b that has entered as described above. Third, the rod b is sprayed with ultra-high pressure water from a nozzle and air from an air nozzle,
While rotating, pull up to a predetermined height.

By moving the rod b upward from below as described above, the contaminated soil c and the surrounding soil are cylindrical and muddy.

In the conventional technique, the contaminated soil c, which has become muddy as described above, is sucked up, stored in a slime pit, transported to a predetermined treatment plant, and appropriately treated.

The contaminated soil c, which is cylindrical and muddy as described above, is injected from the solidifying agent injection nozzle of the rod b with a predetermined amount of solidifying agent, which is the subject of the present invention described below. Is injected while rotating the rod b, and mixed and stirred with the mud-like contaminated soil c.

Thereafter, the rod b is pulled up, and after a predetermined time, the mud-like contaminated soil c is solidified in about 7 hours by using the water absorbing property of the solidifying agent. As a result, the heavy metals of the harmful substances are stabilized and are prevented from being eluted into other surrounding soils.

Next, the solidifying agent of the present invention will be described.

The solidifying agent mainly composed of magnesium oxide is dissolved in water before injection.

The magnesium oxide dissolved as described above is jetted from a nozzle. The magnesium oxide is
Absorbs water contained in muddy contaminated soil,
After a predetermined time (8 to 10 hours), the contaminated soil that has been muddy is solidified.

As described above, heavy metals such as hexavalent chromium or trichlorethylene contained in solidified contaminated soil are stabilized for a long period of time and do not elute into the surrounding soil.

Further, even in the case of the other embodiment which is the solidifying agent of the present invention, the mud-like contaminated soil solidifies after a predetermined time, and the heavy metal does not stably elute into the surrounding soil.

Further, the present invention provides a process for passing a super high pressure water through a boring machine, feeding a compressed air, and solidifying into a soil of a contaminated soil at a predetermined depth which is contaminated by a heavy metal of hexavalent chromium or trichlorethylene. The rod having the water passage of the agent is made to enter a predetermined depth, and after the penetration, the ultra-high pressure water is injected from the water passage of the ultra-high pressure water constituting the rod, and the contamination of a predetermined width and a predetermined height is performed. The soil is made muddy by spraying water, and a soil solidifying agent containing a predetermined amount of magnesium oxide as a main component in predetermined water is passed through the solidifying water passage section of the rod while the rod is rotated while the solidifying agent nozzle is rotated. The muddy soil is mixed and stirred into the muddy soil, and the muddy soil is solidified firmly by using the adsorptive property of the solidifying agent to prevent re-elution of the heavy metal substance. Allowed to method can also be.

[0083]

According to the first aspect of the present invention, there is provided a soil neutral solidifying agent obtained by mixing 10 to 100% by weight of an acidic solidifying aid with 100 parts by weight of magnesium oxide and a mineral containing magnesium oxide. When magnesium and acidic solidification aids are injected into soil such as defective ground or soft ground, they combine with the water contained in the soil and solidify, thereby turning the defective ground or soft ground into a strong ground with good strength. I was able to.

The solidified soil improved by the use of the neutral solidifying agent of the present invention has a PH value of 5 to 9, preferably 5.8 to 8.6. There is an advantage that a safe improved soil free of heavy metal contamination which does not contain is obtained.

The acid hardening aid according to the second aspect of the present invention includes aluminum sulfate, polyaluminum chloride, ferrous sulfate, ferric chloride, sodium oxide, sulfamic acid, phosphoric acid, and an aqueous solution having a pH value of 7%. Among the following phosphorus compounds, a single or a mixture of two or more solidifying agents is a soil neutral solidifying agent.
When a neutral solidifying agent containing at least one kind of solidifying agent is injected into soil such as the same defective ground or soft ground as in claim 1, the magnesium oxide and the acidic solidification aid are mixed with water contained in the soil. It was bonded and solidified, and a good ground with high strength could be formed.

Further, the solidified soil improved by the use of the neutral solidifying agent of the present invention has a PH value of 5 to 9, preferably 5.8 to 8.6. There is an advantage that a safe improved soil free of heavy metal contamination which does not contain is obtained.

The third aspect of the present invention is a soil-neutral solidifying agent in which a water-absorbing agent is used in combination with the solidifying agent. However, the improved ground and the like which were sufficiently hardened even when the hardness was high and the hardness was sufficiently hard could be obtained.

The invention according to claim 4 is characterized in that the water-absorbing agent is one or more of porous inorganic minerals such as activated carbon, activated clay, sepiolite, kieselguhr, zeolite, silica heme and guar gum, calcium sulfate and slag. Since it is a soil-neutral solidifying agent to be used by mixing, the same effect as in claim 3 can be obtained by using the water-absorbing agent.

According to a fifth aspect of the present invention, a neutral solidifying agent containing magnesium oxide as a main component and an acidic solidifying agent mixed with the magnesium oxide is applied to the shallow and deep defective ground or soft ground. 1 to 50% by weight, or mixed and agitated, is mixed or agitated. Therefore, when the neutral solidifying agent is injected, moisture in the shallow and deep defective ground or soft ground is added. The solidification is significantly increased, and furthermore, there is an advantage that a safe improved soil free from the possibility of alkali and heavy metal contamination can be obtained very easily.

According to a sixth aspect of the present invention, in the mud or sludge, a neutral solidifying agent containing magnesium oxide as a main component and an acidic solidifying aid mixed with the magnesium oxide is used in an amount of 2% based on the volume of the soil to be treated. Up to 100% by weight is added and mixed to regenerate as improved soil. Since it is a sludge improvement method, unlike the conventional mud and sludge improvement method, the solidification strength is significantly increased and there is no risk of alkali and heavy metal contamination. Alternatively, it is possible to reliably obtain the subgrade soil of the road.

According to a seventh aspect of the present invention, the contaminated soil contaminated by heavy metal or the like at a predetermined depth is formed into a mud-like state, and a predetermined amount of water and a predetermined amount of magnesium oxide are mixed in the mud-like contaminated soil. A soil solidifying agent containing magnesium as a main component is injected, the solidifying agent is mixed with the soil, the magnesium oxide of the injected solidifying agent reacts to solidify the soil, and the heavy metal is transferred to the adjacent soil. It is a means of preventing elution of heavy metals from contaminated soil that prevents elution of
The injected magnesium oxide absorbs the water contained in the mud state and firmly solidifies the soil in the mud state, stabilizes harmful heavy metals and reliably prevents elution again. Was.

Further, the present invention excavates so-called contaminated soil as one of the conventional means for purifying contaminated soil, transports the excavated soil to another treatment plant, and performs a predetermined purification treatment. In contrast to those in which replacement means for introducing soil not contaminated with heavy metal into the excavated or excavated concavities were used, the soil contaminated by heavy metal and the surrounding soil were sprayed with ultra-high pressure water to form a cylinder. The muddy soil absorbs the water of the muddy soil through the solidified magnesium oxide of the present invention, and solidifies the soil firmly by the solidification function which is a characteristic of the magnesium, thereby preventing the elution of heavy metals again. The prevention means has the advantage that the sequestration of heavy metals in the contaminated soil can be treated at a lower cost than conventional hardening means.

According to the present invention, the soil solidifying agent is a means for preventing water from being mixed with the magnesium oxide to prevent elution of heavy metals and the like in contaminated soil.
It has the same effect as the described invention.

According to a ninth aspect of the present invention, the soil solidifying agent is a means for preventing elution of heavy metals and the like in contaminated soil obtained by mixing 10 to 100% by weight of an acid solidifying aid with 100 parts by weight of magnesium oxide. Can be further solidified.

The invention according to claim 10 is characterized in that the acidic solidification aid has a pH value of aluminum sulfate, polyaluminum chloride, ferrous sulfate, ferric chloride, sodium acid sulfate, sulfamic acid, phosphoric acid, and an aqueous solution. It is the means for preventing elution of heavy metals and the like from contaminated soil in which a single or two or more acidic solidification assistants are mixed among the phosphorus compounds of 7 or less.

The invention according to claim 11 is that the soil solidifying agent is a means for preventing elution of heavy metals and the like in contaminated soil to which ferrous sulfate or ferric chloride is added for stabilizing the heavy metals. It has the same effect as the invention according to claims 7 to 10.

According to a twelfth aspect of the present invention, the soil solidifying agent is a phosphate compound, ferrous sulfate and ferric chloride used alone or as a mixture of two or more acidic solidifying agents to prevent elution of heavy metals and the like from contaminated soil. Since it is a means, it has the same effect as the inventions of claims 7 to 11.

According to a thirteenth aspect of the present invention, the soil solidifying agent is a means for preventing elution of heavy metals and the like in contaminated soil mixed with an acidic solidifying agent of magnesium chloride, and thus has the same effect as the inventions of the seventh to twelfth aspects. .

[Brief description of the drawings]

BRIEF DESCRIPTION OF DRAWINGS FIG. 1 is a diagram showing a state of work for improving a shallow-layer defective ground in a method for improving a shallow-layer defective ground in a method for improving a soil-neutral solidifying agent and ground according to the present invention.

FIG. 2 is a diagram showing a working state at the time of deep ground improvement.

FIG. 3 is a view showing a mechanism in which a solidifying agent is put into mud in a mixing tank and mixed and stirred to produce an improved soil.

FIG. 4 is a system diagram of a filter press according to a second embodiment for separating sludge and the like into a dewatered cake and drainage.

FIG. 5 is a partially cutaway longitudinal sectional view of a means for preventing elution of heavy metals or the like from contaminated soil according to the present invention.

FIG. 6 is a partially cut-away enlarged longitudinal sectional view of a rod used in the prevention means of FIG. 5;

[Explanation of symbols]

 a boring machine b rod c contaminated soil 1 defective ground 2 backhoe 3 improved soil 4 rod 5 boring machine 6 swivel 7 ground 8 stirring blade 9 mixing tank 10 motor 11 shaft 12 blade 13 and 14 hopper 15 improved soil 16 mud pipe 17 Mixing tank 18 Injection hopper 19 Stirring motor 20 Mud feed pipe 21 Driving pump 22 Mud feed pipe 23 Filter press 24 Filter chamber 25 Filter cloth 26 Hydraulic cylinder 27 Dehydration cake 28 Drainage

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) E02D 3/12 101 E02D 3/12 102 102 C09K 103: 00 // C09K 103: 00 109: 00 109: 00 B09B 3/00 ZAB F term (reference) 2D040 AA01 AB01 AB03 AC05 CA08 4D004 AA41 AB03 AC07 CA15 CB27 CC03 CC11 DA03 DA10 4D059 AA09 BF16 BG00 BG03 BJ01 CC04 DA01 DA06 DA08 DA09 DA16 DA17 DA40 DA54 DA06 DA54 CB01 CB03 CB05 CB07 CC02

Claims (13)

[Claims] (1) 100 parts by weight of magnesium oxide, 10 to 10 parts by weight
A soil-neutral solidifying agent comprising 100% by weight of an acidic solidifying aid. 2. The method according to claim 1, wherein the acidic solidification aid is aluminum sulfate,
Polyaluminum chloride, ferrous sulfate, ferric chloride, sodium acid sulfate, sulfamic acid, phosphoric acid, P of aqueous solution
2. The soil neutral solidifying agent according to claim 1, wherein a single or two or more kinds of acidic solidifying aids are mixed among phosphorus compounds having an H value of 7 or less. 3. The improvement soil according to claim 1, wherein a water absorbing agent is used in combination with the solidification agent in the case of an improved soil having a high water content to which the solidification agent is added. Soil neutral solidifying agent. 4. The water-absorbing agent is used alone or as a mixture of two or more of activated carbon, activated clay, sepiolite, silicate earth, zeolite, and porous inorganic minerals such as silica fume and guar gum, calcium sulfate, and slag. The soil neutral solidifying agent according to claim 3, wherein 5. In shallow and deep defective ground or soft ground,
A shallow ground characterized by adding or injecting 1 to 50% by weight of the neutral solidifying agent corresponding to claim 1, 2 or 3 with respect to the volume of the soil to be treated and mixing or stirring to improve the ground with high strength. Layer, deep ground improvement method. 6. The method according to claim 1, wherein the inside of the mud or the sludge is embedded in the sludge.
Alternatively, 2% to 100% by weight of a neutral solidifying agent corresponding to 3 is added to and mixed with the volume of the soil to be treated, and the mixed soil is regenerated as an improved soil. Mud and sludge improvement method. 7. A muddy contaminated soil contaminated with heavy metal or the like at a predetermined depth, wherein said muddy contaminated soil includes:
A soil solidifying agent containing magnesium oxide as a main component, in which predetermined water and a predetermined amount of magnesium oxide are mixed, is injected, and the solidifying agent and the soil are mixed, and the injected magnesium oxide of the solidifying agent reacts. A means for preventing the elution of heavy metals or the like from contaminated soil, wherein the soil is solidified to prevent the heavy metals from being eluted into adjacent soil. 8. The means for preventing elution of contaminated soil such as heavy metals according to claim 7, wherein said soil solidifying agent mixes said magnesium oxide with water. 9. The method according to claim 9, wherein the soil solidifying agent is magnesium oxide 10
9. The means for preventing elution of heavy metals or the like from contaminated soil according to claim 7 or 8, wherein 10 to 100% by weight of an acidic solidification aid is mixed with 0 parts by weight. 10. The method according to claim 1, wherein the acid hardening aid is aluminum sulfate, polyaluminum chloride, ferrous sulfate, ferric chloride,
9. A method according to claim 7, wherein a single or two or more kinds of acidic solidification aids are mixed among the acidic sodium sulfate, sulfamic acid, phosphoric acid and a phosphorus compound having an aqueous solution having a pH value of 7 or less. The means for preventing elution of heavy metals or the like from contaminated soil according to claim 9. 11. The soil solidifying agent according to claim 7, wherein ferrous sulfate or ferric chloride is added for stabilizing the heavy metal.
Or means for preventing elution of heavy metals or the like from contaminated soil according to claim 10. 12. The soil solidifying agent according to claim 7, wherein a phosphate compound, ferrous sulfate and ferric chloride are used alone or in combination of two or more acidic solidifying agents. The means for preventing elution of heavy metals or the like from contaminated soil according to claim 9 or claim 10. 13. The soil hardening agent according to claim 7, wherein an acid hardening agent of magnesium chloride is mixed.
13. The means for preventing elution of heavy metals or the like from contaminated soil according to claim 12.