JP2019181366A - Method for treating mud generated in slurry type shield construction method - Google Patents

Abstract

To provide a method for treating mud generated in a slurry type shield construction method, capable of forming a solidified body having a large cone index and reducing an amount of harmful substances such as heavy metals eluted from the solidified body.SOLUTION: A method for treating mud generated in a slurry type shield construction method including a crushing step of adding a solidifying and insolubilizing agent to mud generated in a slurry type shield construction method and subjecting it to crushing treatment to form crush-treated mud, and a mixing step of adding the solidifying and insolubilizing agent to the crush-treated mud and subjecting it to mixing treatment to form mix-treated mud, wherein in the crushing step and the mixing step, either of a cationic polymer flocculant or an anionic polymer flocculant is not added, and the crushing treatment in the crushing step is carried out until a 50% passing mass percentage of the crushed mud is 18 mm or less and a 80% passing mass percentage is 40 mm or less.SELECTED DRAWING: None

Description

  The present invention relates to a method for treating mud generated in a muddy water type shield method.

The muddy water generated by the muddy water shield method is usually dehydrated using a dehydrator after adding a dehydrating agent to become mud (dehydrated cake). Mud whose water content has been reduced by dehydration is often disposed of as industrial waste. However, in recent years, it is difficult to secure a disposal site and the cost for disposal is high.
In Patent Document 1, as a treatment method capable of effectively using the excavated sediment generated in the muddy water shield method, the soil generated in the muddy water shield method is treated with a primary treated soil and a secondary treatment having a particle size smaller than that of the primary treated soil. After classifying into soil, the modifying agent containing gypsum and the secondary treated soil are mixed to form a mixture, and this mixture is mixed with the primary treated soil or the primary treated soil mixed with the modifying agent. The muddy water type shield construction method is characterized by the method for treating soil.

On the other hand, as a solidified insolubilizing material for solidifying contaminated soil containing heavy metals, etc. to insolubilize heavy metals, for example, Patent Document 2 discloses at least one or more water-soluble substances selected from metal sulfates and metal chlorides. The following (B1) to (B3) with respect to 100 parts by mass of the salt (A):
(B1) After firing a solid containing magnesium carbonate and / or magnesium hydroxide as a main component at 650 to 1000 ° C. to obtain a fired product containing magnesium oxide, the fired product is partially hydrated. Magnesia partially containing magnesium hydroxide produced by
(B2) Magnesia whose ignition loss rate at 1000 ° C. is 1.5 to 12.0% by mass,
(B3) Magnesia having a calcium content of 3.0% by mass or less in terms of CaO,
The processing material, such as heavy metal, characterized by containing 5-50 mass parts of magnesias (B) which satisfy | fill all these conditions is described.

Japanese Patent Laid-Open No. 2001-40984 Japanese Patent No. 5757613

An object of the present invention is to form a solidified body (treated mud) having a large cone index (400 kN / m ² or more) with respect to the mud generated by the muddy water type shield method, and to remove heavy metals, etc. from the solidified body An object of the present invention is to provide a method for treating mud that can reduce the elution amount of harmful substances.

As a result of intensive studies to solve the above-mentioned problems, the present inventor added a solidified insolubilizing material to the mud that is the object to be treated, and then pulverized the solidified insolubilized material into the crushed mud thus obtained. In each treatment, neither a cationic polymer flocculant nor an anionic polymer flocculant is added, and the above pulverization is a 50% passing mass of the mud. It has been found that the above object can be achieved by the method for treating mud until the percentage is 18 mm or less and the 80% passing mass percentage is 40 mm or less, and the present invention has been completed.
That is, the present invention provides the following [1] to [9].

[1] A solidification and insolubilization material is added to the mud generated by the muddy water shield method, and a pulverization process is performed to form a crushed mud, and a solidification and insolubilization material is added to the crushed mud. A method for treating mud generated in a muddy water type shield method, including a mixing step of adding and mixing to form a mud that has been mixed, wherein the cationic polymer is used in the crushing step and the mixing step. Neither a flocculant nor an anionic polymer flocculant is added, and the pulverization in the pulverization step has a 50% passing mass percentage of 18 mm or less and an 80% passing mass percentage of 40 mm or less. A method for treating mud generated in a muddy water type shield method,

[2] A method for treating mud generated in the mud shield method according to [1], wherein the mixing step is performed using a biaxial mixer in the mixing step.
[3] Generated in the muddy water shield method according to [1] or [2], wherein the pulverization time in the pulverization step is 1 to 10 seconds and the mixing time in the mixing step is 0.5 to 5 minutes. How to treat mud.
[4] Any of the above [1] to [3], wherein the ratio of the mass of the solidified insolubilized material added in the pulverizing step and the mass of the solidified insolubilized material added in the mixing step is 1: 4 to 4: 1. A method for treating mud generated by the muddy water type shield method described in the above.
[5] The muddy water shield according to any one of [1] to [4], wherein the solidified and insolubilized material includes at least one selected from a magnesium component having a solidifying action and a calcium component having a solidifying action. A method for treating mud generated by the construction method.
[6] The method for treating mud generated by the muddy water type shield method according to [5], wherein the solidified and insolubilized material further contains at least one selected from metal sulfates and metal chlorides.

[7] The solidified and insolubilized material includes (A) a magnesium-containing material satisfying all the following conditions (1) to (3) as containing the magnesium component, and (B) the following (4) containing the calcium component. And (C) one or more selected from among magnesium and calcium-containing materials satisfying the following condition (5) as containing the magnesium component and the calcium component: The method for treating mud generated in the muddy water type shield method according to the above [6], which is contained in an amount of 5 to 100 parts by mass per 100 parts by mass in total of the metal sulfate and the metal chloride.
(1) Magnesium-containing material containing magnesium oxide obtained by firing a solid material containing magnesium carbonate and / or magnesium hydroxide as a main component at 650 to 1000 ° C., or partially hydrated the magnesium-containing material Magnesium-containing product partially containing magnesium hydroxide produced (2) The ignition loss at 1000 ° C. is 1.5 to 12.0% by mass. Magnesium-containing product (3) The content of calcium is Magnesium-containing material that is 5.0% by mass or less in terms of CaO (4) Calcium-containing material in which the total content of calcium oxide and / or calcium hydroxide is 70% by mass or more in terms of CaO (5) Magnesium content The rate is 5 to 35% by mass in terms of MgO, and the calcium content is 20 to 50% by mass in terms of CaO. Magnesium and calcium-containing material in which the total content of gnesium and calcium is 50% by mass or more [8] The solidified insolubilized material is hemihydrate gypsum, calcium carbonate-containing powder, silica stone powder, crushed stone fine powder, The processing method of the mud produced | generated by the muddy water type shield method in any one of said [1]-[7] containing the auxiliary material which consists of at least 1 sort (s) chosen from olivine powder.
[9] Mud 1 m ³ per generated by the muddy water type shield method, amount of the solidifying insolubilizing material, generated in the muddy water type shield method according to any one of the a 20~250kg [1] ~ [8] How to treat mud.

According to the present invention, a solidified body (treated mud) having a large cone index (400 kN / m ² or more) is formed with respect to the mud generated by the muddy water type shield method, and a heavy metal or the like from the solidified body is formed. The elution amount of harmful substances can be reduced.
Moreover, the obtained solidified body is not handled as industrial waste, for example, and can be used as a material for embankment or a material for landfill.

A method for treating mud generated in the muddy water shield method of the present invention includes a crushing step of adding a solidified insolubilizing material to the mud generated in the muddy water shield method, and performing a pulverization treatment to form a crushed muddy soil. A method for treating mud including a mixing step of adding a solidified and insolubilizing material to the ground mud that has been ground to form a mud that has been subjected to the mixed processing. Neither the water-soluble polymer flocculant nor the anionic polymer flocculant is added, and the pulverization in the pulverization process is such that the 50% passing mass percentage of the crushed mud is 18 mm or less and the 80% passing mass percentage is 40 mm or less. Is to be done.
Hereinafter, each process will be described in detail.

[Crushing process]
This step is a step of adding a solidified insolubilizing material to the mud generated by the muddy water type shield method (hereinafter also referred to as “mud”), and performing a pulverization process to form a crushed mud.
The muddy water type shield method is a kind of shield method and refers to a method of excavating while mixing earth and sand excavated in a chamber.
The “muddy soil generated by the muddy water type shield method”, which is the object of treatment of the present invention, dewaters the muddy water generated by the muddy water type shield method (a mixture of excavated soil and water) to reduce the water content ratio. Mud (dehydrated cake).
Dehydration is usually performed using a general dehydrator such as a belt press, a filter press, a centrifugal dehydrator, a rotary press, a vacuum dehydrator, a screw press, a multi-disc dehydrator, or a multi-plate screw press.
Further, from the viewpoint of efficiently performing dehydration, a dehydrating agent (for example, polyaluminum chloride, water-soluble polymer, etc.) may be added to the muddy water for dehydration.

  As a preferable example of the mud generated by the muddy water type shield method, which is the object to be treated according to the present invention, one that does not satisfy the soil elution standard for the second type of specified hazardous substance in the Soil Contamination Countermeasures Law (2003) (in other words, Then, cadmium and its compound, hexavalent chromium compound, cyanide, mercury and its compound, selenium and its compound, lead and its compound, arsenic and its compound, fluorine and its compound, which are defined as soil elution amount standards, and , Boron and any of its compounds that exceed the upper limit of the soil elution standard (mg / L); in the present specification, these hazardous substances may be collectively referred to as “heavy metals, etc.” .).

The water content ratio of the mud that is the treatment object of the present invention is not particularly limited, but from the viewpoint of reducing the workability in the muddy water type shield method and the treatment cost required for adjusting the water content ratio of the treatment object, it is preferably 30. % Or more, more preferably 40% or more, particularly preferably 50% or more. From the viewpoint of obtaining a larger corn index for the treated mud, preferably 80% or less, more preferably 70% or less, particularly preferably Is 60% or less.
Here, the water content ratio (unit:%) is a value obtained by dividing the mass of water contained in the mud by the mass of the mud in an absolute dry state (“mass of water” × 100 ÷ "Absolute dry mass").

Examples of the solidified and insolubilized material used in the present invention include those containing at least one of a magnesium component having a solidifying action and a calcium component having a solidifying action, metal sulfates, metal chlorides and the like.
Examples of those containing a magnesium component having a solidifying action include magnesium oxide-containing materials and magnesium hydroxide-containing materials. Examples of the magnesium oxide-containing material include light-burned magnesia and light-burned magnesia partial hydrate.
Examples of those containing a calcium component having a solidifying action include calcium oxide-containing materials and calcium hydroxide-containing materials. Examples of the calcium oxide-containing material include quick lime. Examples of the calcium hydroxide-containing material include slaked lime.
Examples of those containing a magnesium component having a solidifying action and a calcium component having a solidifying action include light-burned dolomite and partial hydrates of light-burned dolomite.

Examples of metal sulfates include iron sulfate salts such as ferrous sulfate, ferric sulfate, and polyferric sulfate, and aluminum sulfate salts such as aluminum sulfate, aluminum potassium sulfate, and sodium aluminum sulfate. In addition, the below-mentioned hemihydrate gypsum (an example of auxiliary material) shall not be contained in the example of a metal sulfate here.
Examples of metal chlorides include iron chloride salts such as ferrous chloride and ferric chloride, and aluminum chloride salts such as polyaluminum chloride.

The above-mentioned various solidified and insolubilized materials may be used singly or in combination of two or more, as long as they are appropriately determined according to the water content ratio, pH, etc. of the mud generated by the muddy water type shield method. Good.
Among these, from the viewpoint of further enhancing solidification of mud or insolubilization of heavy metals, etc., a solidified insolubilized material containing at least one selected from a magnesium component having a solidifying action and a calcium component having a solidifying action is preferable, and has a solidifying action. A solidified and insolubilized material containing at least one selected from a magnesium component and a calcium component having a solidifying action, and further including at least one selected from a metal sulfate and a metal chloride is more preferable.
In the case where the solidified insolubilizing material contains at least one selected from a magnesium component having a solidifying action and a calcium component having a solidifying action, and further contains at least one selected from a metal sulfate and a metal chloride. As a more preferable example of the solidified and insolubilized material to be used, (A) a magnesium-containing material satisfying all of the following conditions (1) to (3) as containing a magnesium component having a solidifying action, and (B) a calcium component having a solidifying action. Calcium-containing material satisfying the following condition (4) as containing, and (C) containing magnesium and calcium satisfying the following condition (5) as containing a solidifying magnesium component and a solidifying calcium component A total of one or more selected from among the above-mentioned metal sulfates and Total 100 parts by weight per genus chloride, 5 to 100 parts by weight, preferably 10 to 80 parts by weight, particularly preferably those containing an amount of 20 to 60 parts by weight.

(1) Magnesium-containing material containing magnesium oxide obtained by firing a solid material containing magnesium carbonate and / or magnesium hydroxide as a main component at 650 to 1000 ° C., or partially hydrated the magnesium-containing material Magnesium-containing product partially containing magnesium hydroxide produced (2) The ignition loss at 1000 ° C. is 1.5 to 12.0% by mass. Magnesium-containing product (3) The content of calcium is Magnesium-containing material that is 5.0% by mass or less in terms of CaO (4) Calcium-containing material in which the total content of calcium oxide and / or calcium hydroxide is 70% by mass or more in terms of CaO (5) Magnesium content The rate is 5 to 35% by mass in terms of MgO, and the calcium content is 20 to 50% by mass in terms of CaO. Magnesium and calcium-containing material in which the total content of gnesium and the calcium content is 50% by mass or more Details of this solidified insolubilized material (preferred example) are disclosed in Japanese Patent No. 5757613 (the above-mentioned Patent Document 2). As described.
In the above condition (1), the “main component” means that it is preferably 80% by mass or more, more preferably 85% by mass or more, and particularly preferably 90% by mass or more.

In addition, when the pH of the elution test solution for mud generated by the muddy water type shield method is low (for example, 6.0 or less, preferably 5.0 or less, more preferably 4.0 or less), elution of the treated mud is performed. From the viewpoint of easily adjusting the pH of the test solution to a neutral region (for example, 5.8 to 8.6 which is the discharge standard value), the solidified insolubilizing material is composed of a magnesium component having a solidifying action and calcium having a solidifying action. It preferably contains at least one selected from the components and does not contain at least one selected from metal sulfates and metal chlorides.
Further, as a more preferable example of a solidified insolubilizing material containing at least one of a magnesium component having a solidifying action and a calcium component having a solidifying action and not containing at least one selected from metal sulfates and metal chlorides. (A) Magnesium-containing material satisfying all of the conditions (1) to (3) described above as containing a magnesium component having a solidifying action, (B) (4) mentioned above as containing a calcium component having a solidifying action Selected from among the calcium-containing material satisfying the above condition and (C) the magnesium-containing and calcium-containing material satisfying the above-mentioned condition (5) as containing the solidifying calcium component and the solidifying calcium component. The thing which consists of 1 or more types selected.

The solidified insolubilized material can contain various auxiliary materials for the purpose of further enhancing the effect of solidifying mud or insolubilizing heavy metals.
Examples of auxiliary materials include hemihydrate gypsum, calcium carbonate-containing powder, silica stone powder, fine crushed stone powder, and olivine powder. These may be used individually by 1 type and may be used in combination of 2 or more type.
Among these auxiliary materials, details of hemihydrate gypsum, calcium carbonate-containing material, silica stone powder, and crushed stone fine powder are as described in Japanese Patent No. 5757613 (Patent Document 2 described above).
As the olivine powder, any of calcined olivine powder (for example, calcite obtained by calcining olivine at 300 to 600 ° C. for 0.5 to 1.5 hours) and uncalcined olivine powder may be used. it can.
The amount of auxiliary material varies depending on the type of auxiliary material and its purpose, but is usually preferably 500 parts by mass or less, more preferably 400 parts by mass or less, per 100 parts by mass of the above-mentioned metal salt.

  In the pulverization step and the mixing step (described later), the solidified insolubilized material may be prepared by adding a previously prepared solidified insolubilized material to the mud, and each material constituting the solidified insolubilized material is separately added to the mud (for example, a magnesium component and A mixture of metal salts and a mixture of calcium component and metal salt may be added separately to the mud).

Examples of means used for crushing mud containing solidified and insolubilized material include a multi-shaft hammer mixer, a vertical triaxial crusher, and the like. Moreover, when the moisture content of the mud is low, a self-propelled crusher may be used. Among these, the vertical triaxial crusher is particularly preferable because it can be pulverized in a short time.
In addition, the grinding | pulverization in this process shall include mixing of each material inevitably generate | occur | produced when adding a solidification insolubilization material to the mud which becomes a process target, and grind | pulverizing.
The pulverization is performed until the 50% passing mass percentage of the crushed mud is 18 mm or less, preferably 14 mm or less, more preferably 12 mm or less, further preferably 10 mm or less, and particularly preferably 6 mm or less. If the rate is 18 mm or less, a large cone index can be obtained for the solidified body (treated mud), and the elution amount of harmful substances (heavy metal, etc.) from the solidified body (treated mud) is reduced. be able to.

The pulverization is performed until the 80% passing mass percentage of the crushed mud is preferably 40 mm or less, more preferably 30 mm or less, still more preferably 26 mm or less, and particularly preferably 20 mm or less. If the rate is 40 mm or less, a larger cone index can be obtained for the solidified body (treated mud), and the amount of harmful substances eluted from the solidified body (treated mud) can be reduced. .
In addition, “50% passing mass percentage” or “80% passing mass percentage” means the particle size accumulation in accordance with “JIS A 1204 (2009)” (soil particle size test method) for crushed mud. It refers to the “particle size of the mud with a passing mass percentage of 50%” or “the particle size of the mud with a passing mass percentage of 80%” obtained from the curve when a curve is created.

  The pulverization time in the pulverization step (the time required for the pulverization treatment) is preferably 1 to 10 seconds, more preferably 2 to 8 seconds, and particularly preferably 3 to 5 seconds. If the time is 1 second or longer, a larger corn index can be obtained for the solidified body (treated mud), and the amount of toxic substances eluted from the solidified body (treated mud) should be reduced. Can do. If the time is 10 seconds or less, the time required for the treatment of the mud can be further shortened.

[Mixing process]
This step is a step that is performed after the pulverization step, and is a step of adding a solidified insolubilizing material to the crushed mud obtained in the pulverization step and performing a mixing process to form a mixed mud. It is.
As the solidified and insolubilized material, the same materials as used in the pulverization step can be used.
Examples of mixing means used for mixing crushed mud and solidified insolubilized material include backhoes, various mixers (for example, paddle mixers such as biaxial mixers, forced stirring mixers, pan mixers, rotary hammer mixers) 4 axis serial mixing mixer etc.).
Among them, the solid particles constituting the mud are coated with a solidified insolubilizing material, and a granulated product having the particles as a core is formed, whereby the cone index of the mixed mud can be further increased. Therefore, a two-axis mixer is preferable.

Mixing is carried out until the 50% passing mass percentage of the mixed mud is 20 mm or less, preferably 19 mm or less, more preferably 15 mm or less, further preferably 12 mm or less, and particularly preferably 8 mm or less. If the rate is 20 mm or less, a large cone index can be obtained for the solidified body (treated mud), and the amount of toxic substances (heavy metal, etc.) eluted from the solidified body (treated mud) is reduced. be able to.
Further, the mixing is performed until the 80% passing mass percentage of the mixed mud is preferably 40 mm or less, more preferably 30 mm or less, still more preferably 26 mm or less, and particularly preferably 20 mm or less. If the rate is 40 mm or less, a larger cone index can be obtained for the solidified body (treated mud), and the amount of harmful substances eluted from the solidified body (treated mud) can be reduced. .

  The mixing time in the mixing step is preferably 0.5 to 5 minutes, more preferably 0.75 to 4 minutes, and particularly preferably 1 to 3 minutes. If this time is 0.5 minutes or more, a larger corn index can be obtained for the solidified body (treated mud), and the amount of toxic substances eluted from the solidified body (treated mud) can be reduced. can do. If this time is 5 minutes or less, the time required for the treatment of the mud can be further shortened.

The amount of solidified insolubilized material added per 1 m ^{3 of} mud that is the object of the present invention (total amount of solidified insolubilized material added in the pulverization step and solidified insolubilized material added in the mixing step) is preferably 20 to 250 kg, more Preferably it is 30-200 kg, More preferably, it is 40-170 kg, Most preferably, it is 50-160 kg. When the added amount is 20 kg or more, the elution amount of heavy metals and the like (particularly the second type specific harmful substance) can be suppressed to a lower level, and the effect of insolubilization can be further enhanced. Moreover, a larger corn index can be obtained for the solidified body (treated mud). When the addition amount is 250 kg or less, an excessive increase in processing cost can be avoided.

The ratio of the mass of the solidified insolubilized material added in the pulverization step to the mass of the solidified insolubilized material added in the mixing step is preferably 1: 4 to 4: 1, more preferably 1: 3.5 to 3.5: 1. Particularly preferred is 1: 3 to 3: 1. When the ratio is within the above numerical range, a larger cone index can be obtained for the solidified body (treated mud), and the amount of toxic substances eluted from the solidified body (treated mud) can be reduced. be able to.
Also, by adding the solidified insolubilizing material in two portions (added in each of the pulverization step and the mixing step), a polymer flocculant (particularly, a cationic polymer flocculant and an anionic polymer flocculant) is added. Even without addition, compared to the case where the polymer flocculant is added, a larger corn index can be obtained for the solidified body (treated mud) than the same, and from the solidified body (treated mud) The amount of toxic substance elution can be reduced to the same level or more.

The treated mud obtained by the method for treating mud according to the present invention preferably satisfies the soil elution amount standard of the second type specific harmful substance in the Soil Contamination Countermeasures Law (2003). Mud that satisfies this standard can be suitably used as embankment material or landfill material.
Here, the amount of soil leaching of Class II Specified Hazardous Substances was determined using the method described in the Ministry of the Environment Notification No. 18 “Matters for Measuring Soil Elution Amount” on March 6, 2003. Then, an elution test solution can be prepared and measured according to “JIS K 0102 (2013)”.
The treated mud obtained in the present invention preferably has a pH of the elution test solution in the range of 5.8 to 8.6.
Here, the pH of the treated mud elution test solution can be measured according to “JIS K 0102 (2013) 12.1 Glass Electrode Method”.

Cone index of treated mud (solidified) as the value at the time of 6 hours after the time of completion of the processing of mud, preferably 400 kN / ^{m 2} or more, more preferably 420kN / ^{m 2} or more, more preferably 460 kN / m ² or more, particularly preferably 500 kN / m ² or more.
In addition, if it is 400 kN / m < ² > or more, since it has sufficient intensity | strength, it can be used conveniently as a material for embankment or a landfill. In addition, the treated mud can be easily transported.
Here, the cone index is determined according to “JIS A 1210 (2009)” (method of soil compaction test by tamping). At the time point after 6 hours from the end, the measurement can be performed according to “JIS A 1228 (2009)” (cone index test method for compacted soil).

EXAMPLES The present invention will be specifically described below with reference to examples, but the present invention is not limited to these examples.
[Materials used]
The materials used are as shown below.
(A) Mud A: muddy water (specific gravity: 1.12 g / cm ³ , moisture content: about 400%), 2.5 kg / m of dehydrating agent (trade name “Soil Fresh P-101” manufactured by Kurita Kogyo Co., Ltd.) ³ was added, and then dehydrated for 60 minutes using a dehydrator (manufactured by Nippon Enviro Kogyo Co., Ltd., filter press: model “KPF-75PR”). Mud (b) mud B: mud (specific gravity) shown in Table 1 : 1.12 g / cm ³ , water content ratio: about 400%), after adding a dehydrating agent (trade name “Soil Fresh P-101” manufactured by Kurita Kogyo Co., Ltd.) to an amount of 2.5 kg / m ³ , followed by dehydration Using a machine (Nippon Enviro Kogyo Co., Ltd., filter press: model “KPF-75PR”), dehydrated for 60 minutes, mud soil shown in Table 1 (c) solidified insolubilized materials A to H: each material shown in Table 2 (D) Polymer flocculant: reverse phase emulsion Anionic polyacrylamide, Pacific Ocean shield mechanics Co., Ltd., trade name "SP-α"
(E) Magnesium-containing material: Magnesite (having a content of magnesium carbonate of 90% by mass or more) was fired at 850 ° C. for 60 minutes using an electric furnace (manufactured by Chugai Engineering Co., Ltd., model “KSL-2”). After the light-burned magnesia was obtained, the light-burned magnesia was pulverized with a ball mill and the particle size was adjusted so that the Blaine specific surface area was 6,300 cm ² / g. (F) Calcium-containing material: Slaked lime, manufactured by Okutama Kogyo Co., Ltd. Special name (g) Magnesium and calcium-containing material: Dolomite (CaO: MgO mass ratio (CaO: MgO) = 1.8: 1.0) at 790 ° C. for 60 minutes, electric furnace (manufactured by Chugai Engineering Co., Ltd., model number) After calcining using “KSL-2”), lightly burned dolomite was obtained, and then the lightly burned dolomite was pulverized with a ball mill to give a specific surface area of 5,000 cm ² / g. In addition, the said magnesium containing material corresponds to the magnesium containing material which satisfy | fills all the conditions of above-mentioned (1)-(3) which is a preferable example of a solidification insolubilization material.
The said calcium containing material corresponds to the calcium containing material which satisfy | fills all the conditions of above-mentioned (4) which is a preferable example of a solidification insolubilization material.
The said magnesium and calcium containing material corresponds to the magnesium and calcium containing material which satisfy | fills all the conditions of above-mentioned (5) which is a preferable example of a solidification insolubilization material.

Hereinafter, the mud treatment conditions 1 to 8 (see Table 3) in Examples and Comparative Examples will be described in detail.
[Processing condition 1]
In a multi-axis hammer type mixer (Okutama Kogyo Co., Ltd., multi-axis rotary hammer type mixer (S-4R type)), mud soil and solidified insolubilized material to be treated are put, and the rotational speed shown in Table 3 is 1 The grinding process was performed for ~ 3 seconds (grinding step).
Next, the crushed mud and solidified insolubilized material are put into a twin-screw mixer (Fuji-1000, manufactured by Fuji Machine Co., Ltd.), and mixed for 1 minute at the number of revolutions shown in Table 3 (mixing) Step), a treated mud (mixed mud) was obtained.
[Processing conditions 2 to 3]
Treated mud (mixed) in the same manner as in treatment condition 1 except that a vertical triaxial crusher ("Multi crusher (BB-50)" manufactured by Fuji Machine Co., Ltd.) is used instead of the multi-shaft hammer type mixer. Treated mud).
[Processing condition 4]
Solidified and insolubilized material was added to the mud to be treated.
[Processing conditions 5-6]
In a multi-axis hammer type mixer (Okutama Kogyo Co., Ltd., multi-axis rotary hammer type mixer (S-4R type)), mud soil and solidified insolubilized material to be treated are put, and the rotational speed shown in Table 3 is 1 The pulverization process was performed for ~ 3 seconds (a pulverization step) to obtain a processed mud (crushed mud).
[Processing conditions 7 to 8]
Put muddy soil and solidified insolubilized material into a vertical triaxial crusher ("Multi-crusher (BB-50)" manufactured by Fuji Machine Co., Ltd.). The treatment was performed (pulverization step) to obtain a treated mud (crushed mud).

For each of the mud after the pulverization treatment and the mud after the mixing treatment, a particle size accumulation curve is prepared in accordance with “JIS A 1204 (2009)” (soil particle size test method), and 50% passing mass is obtained from the curve. Percentage and 80% passing mass percentage were obtained. The results are shown in Table 3.
In the processing conditions 1 to 8, the solidified and insolubilized materials A to C and E to H are prepared by mixing each material (metal sulfate, magnesium component, etc.) in advance and treating the mixture (solidified insolubilized material). Used by adding to the product. The solidified insolubilizing material D was used by previously mixing aluminum sulfate and a magnesium-containing material, and adding the mixture and polyaluminum chloride to the object to be treated almost simultaneously.
Moreover, in process conditions 1-8, even if it was a case where any of the mud A and the mud B were made into the object, the numerical value of 50% passage mass percentage and 80% passage mass percentage was the same.

[Examples 1 to 10]
About the mud of the kind shown in Table 4, it processed on the processing conditions shown in Table 3 and Table 4. The passing mass percentage and the 80% passing mass percentage of the mud after the pulverization treatment and the mud after the mixing treatment were as shown in Table 3.
For the treated mud soil, the corn index (value after 6 hours from the end of the mixing process), the amount of soil leaching of harmful substances (fluorine and arsenic), and the pH of the elution test solution were measured using the above-described method. . Measurement was performed on 10 specimens, and the average value was taken as the measurement result.
In addition, the soil elution standard value of the second kind specific harmful substance in fluorine soil pollution measures method (2003) is less than 0.8 mg / liter, and second in arsenic soil pollution measures method (2003) The soil elution standard value for species-specific hazardous substances is less than 0.01 mg / liter.

[Comparative Examples 1-8]
About the mud of the kind shown in Table 4, it processed on the processing conditions shown in Table 3 and Table 4.
When the polymer flocculant was added (Comparative Examples 2, 4 to 7), the amount of the polymer flocculant shown in Table 4 was added to the mixer simultaneously with the solidified and insolubilized material.
Table 3 shows the 50% passing mass percentage and 80% passing mass percentage of the mud after the pulverization treatment.
In addition, the corn index of the treated mud soil (value after 6 hours from the end of the grinding process), the soil elution amount of harmful substances (fluorine and arsenic), and the pH of the elution test solution were the same as in Example 1. It was measured.
The results are shown in Table 4.

From Table 4, in Examples 1-10, since a cone index of 435 kN / m ² or more is obtained in a short time (6 hours), handling (transportation, etc.) of the treated mud becomes easy, and Transport of treated mud can be started early. Moreover, since the obtained processed mud has sufficient strength, it can be used as a material for embankment or a landfill.
Further, from comparison between Example 1 (50% passing mass percentage of mud after pulverization treatment: 16 mm) and Example 3 (50% passing mass percentage of mud after pulverization treatment: 6 mm), 50 of mud after pulverization treatment was obtained. It can be seen that when the% passing mass percentage is small, the cone index is large and the amount of fluorine dissolved into the soil is small.
Moreover, from the comparison between Example 1 and Comparative Example 1, the comparison between Example 2 and Comparative Example 3, and the comparison between Example 10 and Comparative Example 8, the mixing step is performed after the pulverization step, and the solidified and insolubilized material is added to each of them. According to the method added in the process (Examples 1, 2, and 10), it can be seen that the cone index is large and the amount of fluorine dissolved into the soil is small.
Further, from the comparison between Example 1 and Comparative Example 2, in Example 1, although the polymer flocculant was not used, the corn index was larger than that in Comparative Example 2, and the amount of fluorine dissolved into the soil was higher. I understand that it is small. Similarly, the comparison between Example 2 and Comparative Example 4 shows that the cone index is larger than that of Comparative Example 4 (using the polymer flocculant) although Example 2 does not use the polymer flocculant. And, it can be seen that the amount of fluorine dissolved into the soil is small.

Claims (9)

A crushing step of adding solidified insolubilizing material to the mud generated by the muddy water shield method, crushing, and forming crushed mud,
A method for treating mud generated in a muddy water type shield method, including a mixing step of adding a solidified insolubilizing material to the crushed mud and performing a mixing process to form a mixed mud,
In the pulverization step and the mixing step, neither a cationic polymer flocculant nor an anionic polymer flocculant is added,
Crushing in the crushing step is performed until the 50% passing mass percentage of the crushed mud is 18 mm or less and the 80% passing mass percentage is 40 mm or less. Processing method.   The method for treating mud generated in the muddy water type shield method according to claim 1, wherein in the mixing step, mixing treatment is performed using a twin-screw mixer.   The method for treating mud generated in the muddy water shield method according to claim 1 or 2, wherein the grinding time in the grinding step is 1 to 10 seconds, and the mixing time in the mixing step is 0.5 to 5 minutes.   The ratio of the mass of the solidification insolubilization material added in the said grinding | pulverization process and the mass of the solidification insolubilization material added in the said mixing process is 1: 4-4: 1. A method for treating mud generated in the muddy water shield method.   The said solidification insolubilization material contains at least 1 sort (s) chosen from the magnesium component which has a solidification effect | action, and the calcium component which has a solidification effect | action, It generate | occur | produces with the muddy water type shield method of any one of Claims 1-4 How to treat mud.   The method for treating mud generated by the muddy water type shield method according to claim 5, wherein the solidified and insolubilized material further contains at least one selected from a metal sulfate and a metal chloride. The solidified and insolubilized material is (A) a magnesium-containing material that satisfies all the following conditions (1) to (3) as containing the magnesium component, and (B) the following (4) condition as containing the calcium component. A total of at least one selected from the group consisting of a calcium-containing material to be filled, and (C) magnesium and a calcium-containing material satisfying the following condition (5) as containing the magnesium component and the calcium component: The processing method of the mud produced | generated by the muddy water type | mold shield construction method of Claim 6 included in the quantity of 5-100 mass parts per 100 mass parts in total of a sulfate and the said metal chloride.
(1) Magnesium-containing material containing magnesium oxide obtained by firing a solid material containing magnesium carbonate and / or magnesium hydroxide as a main component at 650 to 1000 ° C., or partially hydrated the magnesium-containing material Magnesium-containing product partially containing magnesium hydroxide produced (2) The ignition loss at 1000 ° C. is 1.5 to 12.0% by mass. Magnesium-containing product (3) The content of calcium is Magnesium-containing material that is 5.0% by mass or less in terms of CaO (4) Calcium-containing material in which the total content of calcium oxide and / or calcium hydroxide is 70% by mass or more in terms of CaO (5) Magnesium content The rate is 5 to 35% by mass in terms of MgO, and the calcium content is 20 to 50% by mass in terms of CaO. The total content and the content of the calcium magnesium is magnesium is not less than 50 wt% and the calcium-containing compound   The said solidification insolubilization material of any one of Claims 1-7 containing the auxiliary material which consists of at least 1 sort (s) chosen from hemihydrate gypsum, calcium carbonate containing powder, quartzite powder, crushed stone fine powder, and olivine powder. A method for treating mud generated in the muddy water shield method. The treatment of mud generated in the mud shield method according to any one of claims 1 to 8, wherein the amount of the solidified insolubilizing material added is 20 to 250 kg per 1 m ^{3 of} mud generated in the mud shield method. Method.