JP2017179341A - Countermeasure material for pollution by heavy metal or the like, and countermeasure method for pollution by heavy metal or the like using the countermeasure material for pollution - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a countermeasure material for pollution by heavy metal or the like capable of insolubilizing the heavy metal or the like in soil, enhancing strength by solidifying the soil, suppressing re-sludging, and maintaining pH of a modified soil in a neutral range, and provide a countermeasure method for pollution by heavy metal or the like using the countermeasure material for pollution.SOLUTION: The countermeasure material for pollution by heavy metal or the like contains semi-burnt dolomite, ferrous sulfate, amorphous calcium silicate and/or calcium carbonate, and a polymeric material as essential inclusion components, with the amorphous calcium silicate and/or calcium carbonate of 50 mass% or more, the semi-burnt dolomite of 5 to 30 mass%, the ferrous sulfate of 5 to 45 mass%, and the polymeric material of 0.1 to 10 mass% by outer percentage based on total mass of the amorphous calcium silicate and/or calcium carbonate, the semi-burnt dolomite, and the ferrous sulfate.SELECTED DRAWING: None

Description

  The present invention relates to a pollution control material for heavy metals and the like, and a pollution control method for heavy metals using the pollution control material, and in particular, insolubilizes heavy metals and the like, and improves the strength of the treated soil by solidification performance and re-mudging the treated soil. The present invention relates to a pollution control material for heavy metals and the like having a soil reforming performance capable of suppressing and maintaining soil pH at a neutral level, and a pollution control method for heavy metals and the like using the pollution control material.

Conventionally, insolubilizing materials such as heavy metals in soil include iron powder-based insolubilizing materials such as ferric chloride and ferrous sulfate, cement-based insolubilizing materials, magnesium oxide (MgO) -based insolubilizing materials, quicklime and gypsum systems, blast furnaces Soil solidifying materials such as slag materials are known.
Iron powder-based insolubilizing materials such as ferric chloride and ferrous sulfate have a problem that heavy metals that can be insolubilized are limited to arsenic and it is difficult to cope with complex contamination.

Cement-based solidified materials, MgO-based solidified materials, or soil solidified materials using quicklime or blast furnace slag-based materials have been proposed.
However, due to the influence of these cements, quicklime, etc., the pH of the soil after modification becomes 10 or more and the alkalinity becomes strong, and the pH of the insolubilized soil remains high for a long time. It is possible that groundwater will flow out to the surrounding environment and affect vegetation. Moreover, since the heavy metal insolubilization ability is low, there is a problem that heavy metals that have not been eluted in the neutral region are eluted.

As a magnesium oxide (MgO) -based solidifying material, a solidified and insolubilized material obtained by adding an organic polymer flocculant and a plurality of insolubilizing aids to improve soil strength is proposed in Japanese Patent Application Laid-Open No. 2003-225640 (Patent Document 1). Has been.
Although such materials are excellent in solidification and insolubilization properties, the pH is likely to be alkaline compared to untreated soil, and it may affect the surrounding environment in the same way as cement-based solidification materials. There is a problem that the scope of application is limited.

In order to prevent soil pH from becoming alkaline, JP 2014-185300 A (Patent Document 2) is based on gypsum and blast furnace slag, and is added with magnesium oxide or aluminum sulfate so that the pH becomes neutral. Adjusted soil consolidation materials have been proposed.
However, the pH is kept neutral, but the use index of the improved soil is limited because the cone index of the improved soil is as low as about 200 to 400. Moreover, in order to improve the corn index to 200 to 400 kN / m ^2, it is necessary to add 100 kg or more of solidifying material per 1 m ³ of soil, which is not appropriate in terms of increase in the amount of improved soil and cost. The insolubilization performance is not described.
Moreover, since the dihydrate gypsum which is a hydration product is water-soluble, there is a problem that the gypsum-based solidified material is re-mudged in an environment where it is exposed to moisture such as rainwater for a long time.

  In the past, when modifying soil strength, such as improving the strength of heavy metal contaminated soil, an insolubilizing material and a solidifying material were added separately, but a material capable of expressing the solidifying performance and insolubilizing performance with a single material is expected. In addition, there is a growing need for materials in which the pH of the improved soil becomes neutral in order to suppress the influence on the surrounding environment.

As a pH-neutral solidified insolubilizing material, Japanese Patent No. 5748015 (Patent Document 3) proposes a pH-neutral solidifying insolubilized material combining light-burned MgO, aluminum sulfate, and ferrous sulfate. No. 5315096 (Patent Document 4) proposes a pH neutral solidified insolubilized material containing calcined gypsum (hemihydrate gypsum), an aluminum compound, a calcium component and / or a magnesium component.
However, although these conventional solidified and insolubilized materials are excellent in pH neutrality maintaining ability and insolubilizing performance, gypsum is the base as in the case of pH neutralized solidified materials. it and the becomes low as about 200 kN / m ^2, the soil having improved strength by solidifying the treated soil is external moisture in the long term limitations in the scope of improved soil because of the risk of re-mud of There is a problem of receiving.

JP 2003-225640 A JP 2014-185300 A Japanese Patent No. 5748015 Japanese Patent No. 5315096

  The object of the present invention is to solve the above-mentioned problems, insolubilize heavy metals and the like in the soil, has both solidification performance and re-mudging suppression function to improve and improve the strength of the treated soil, An object of the present invention is to provide a pollution control material such as heavy metal capable of maintaining the performance of maintaining pH neutral.

  Another object of the present invention is to apply the above-mentioned anti-pollution material for heavy metals to the soil contaminated with heavy metals to insolubilize heavy metals, etc., and to improve strength and suppress re-mudification by solidifying the treated soil. It is to provide a heavy metal pollution control method using heavy metal pollution control materials that demonstrate the soil modification performance.

  This invention discovered that the said subject can be solved by including the specific material as an essential content material by a specific compounding ratio, etc., and came to this invention.

(1) Anti-contamination materials such as heavy metals include semi-calcined dolomite, ferrous sulfate, amorphous calcium silicate and / or calcium carbonate, and a polymer material as essential components, and include amorphous calcium silicate and / or 50% by mass or more of calcium carbonate, 5 to 30% by mass of semi-baked dolomite, and 5 to 45% by mass of ferrous sulfate, and a polymer material containing amorphous calcium silicate and / or carbonic acid It is an anti-contamination material for heavy metals and the like, characterized by containing 0.1 to 10% by mass in an outer ratio with respect to the total mass of calcium, semi-baked dolomite and ferrous sulfate.

  (2) In the pollution control material for heavy metals and the like of (1) above, the pollution control material for heavy metals and the like is in a powder form.

(3) In the anti-contamination material such as heavy metal as described in (1) or (2) above, the semi-fired dolomite is a residual CaMg (CO ₃ ) ₂ phase in a dolomite fired product analyzed using a Rietveld method by powder X-ray diffraction The content of is 0.4 ≦ x ≦ 35.4 (mass%).

(4) In the pollution control material for heavy metals such as any one of (1) to (3) above, amorphous calcium silicate is at least one selected from the group consisting of blast furnace slag and steelmaking slag, and the polymer material is organic. A polymer flocculant and / or a thickener, wherein the organic polymer flocculant is selected from the group consisting of polyacrylamide, polyacrylic acid ester, polyamidine, polyacrylic acid soda, polyethylene oxide, and sodium acrylate-acrylamide copolymer. It is at least one selected, and the thickener is at least one selected from the group consisting of a cellulose thickener, a polyamide thickener, and a polyvinyl alcohol thickener.

(5) The heavy metal pollution control method is a heavy metal pollution control method characterized by using any of the above-mentioned heavy metal pollution control materials mixed with soil.

The anti-pollution material for heavy metals and the like and the construction method for anti-pollution of heavy metals using the anti-corrosion material of the present invention can effectively insolubilize heavy metals etc. in the soil, and it is said that strength improvement by solidification of treated soil and re-mudging suppression While having the property of modifying soil, the pH of the soil treated with the pollution control material such as heavy metal according to the present invention can be kept neutral.
Therefore, in the past, the insolubilized soil became alkaline, and strong alkaline groundwater flowed out to the surrounding environment due to rainfall, etc., and there was concern about the impact on vegetation. Therefore, since the pH of the improved soil is neutral, it is possible to cope with the site where the conventional insolubilizing material could not be applied, and the application range of soil treatment contaminated with heavy metals can be expanded.
In addition, since re-mudging due to moisture from the outside can be suppressed, landfill treatment on the lake shore or coast can be made possible.
In particular, if the amount of lead, arsenic, and fluorine that are abundant in naturally contaminated soil is slightly above the soil elution standard, the effect of insolubilization and soil improvement performance can be achieved with a small addition amount. .

The present invention is illustrated by the following preferred examples, but is not limited thereto.
The anti-contamination material such as heavy metal of the present invention comprises semi-calcined dolomite, ferrous sulfate, amorphous calcium silicate and / or calcium carbonate, and a polymer material as essential components, amorphous calcium silicate and / or 50% by mass or more of calcium carbonate, 5 to 30% by mass of semi-baked dolomite, and 5 to 45% by mass of ferrous sulfate, and a polymer material containing amorphous calcium silicate and / or carbonic acid It is an anti-contamination material such as heavy metals, which is contained in a proportion of 0.1 to 10% by mass with respect to the total mass of calcium, semi-baked dolomite and ferrous sulfate.

  Preferably, the pollution control material such as heavy metal of the present invention is in a powder form. By being in a powder form, handling and workability at the construction site are facilitated. Moreover, when it mixes with soil, it reacts with the water | moisture content in soil quickly, and can adsorb | suck heavy metals etc. and insolubilize. Further, the amorphous calcium silicate and / or calcium carbonate or the polymer material absorbs water and reacts, whereby the soil can be solidified and the soil can be efficiently modified.

  Here, heavy metals and the like mean heavy metals and halogens, and examples of heavy metals include one or more of manganese, chromium, copper, cadmium, mercury, selenium, lead, arsenic, cadmium, and the like. Examples of halogens include dioxins such as chlorine and fluorine, trichlorethylene, tetrachloromethane, chlorinated diphenyl, chlorinated paraffin, etc., and boron contained in type 2 specified hazardous substances stipulated in the Soil Contamination Countermeasures Law However, it is not limited to these heavy metals and halogens.

  The present invention contains semi-calcined dolomite, ferrous sulfate, amorphous calcium silicate and / or calcium carbonate, and a polymer material as essential materials in pollution control materials such as heavy metals, and each content is described above. By making the amount within the range, it is possible to effectively insolubilize heavy metals and the like, improve the strength of the improved soil (improvement of solidification performance) and suppress re-mudification, The above-described effect of maintaining the pH of the improved soil at neutrality can also be achieved.

As the semi-fired dolomite that is an essential material used for the pollution control material such as heavy metal of the present invention, any semi-fired dolomite available in the market can be used, and the composition of the production area and raw material dolomite is not limited.
Dolomite has a double salt structure in which the molar ratio of limestone CaCO ₃ and magnesite MgCO ₃ is 1: 1, and Ca ²⁺ ions and Mg ²⁺ ions are alternately layered with CO ₃ ^2- groups in between. In general, the magnesium carbonate is 10 to 45% by mass. Dolomite is present in large amounts in Japan, and adsorbents such as heavy metals using dolomite are advantageous from the viewpoint of cost and environmental burden.

  Semi-calcined dolomite contributes greatly to the insolubilization performance of heavy metals, etc., and has a pH of 9 to 10 and slightly alkaline compared to MgO-based and lightly calcined dolomite. It is something that can be done.

In particular, as the semi-fired dolomite, the content of residual CaMg (CO ₃ ) ₂ phase in the dolomite fired product analyzed using the Rietveld method by powder X-ray diffraction is 0.4 ≦ x ≦ 35.4 (mass%) The semi-baked dolomite which becomes) can be used suitably.
This is because the CaMg (CO ₃ ) ₂ phase contained in the semi-calcined dolomite is quantified and the residual amount is within the above range, so that the difference in composition depending on the origin of the raw dolomite ore, the calcining temperature, etc. This is because dolomite can have the most excellent adsorption performance such as heavy metals regardless of the setting of firing conditions.

Dolomite shows a decomposition reaction represented by CaMg (CO ₃ ) ₂ → MgO + CaCO ₃ + CO ₂ by firing. It is considered that pores are formed by the above-described thermal decomposition by dolomite firing and exhibit insolubilization ability such as heavy metals.
In the present invention, the residual amount of the dolomite phase (CaMg (CO ₃ ) ₂ phase) in the semi-fired dolomite obtained by firing dolomite is analyzed by the Rietveld method using powder X-ray diffraction, and the residual CaMg (CO ₃ ) ₂ phase is analyzed. Is a semi-calcined dolomite having a content of 0.4 ≦ x ≦ 35.4 (mass%), preferably 1.8 ≦ x ≦ 17.4 (mass%), the dolomite is insolubilized with excellent heavy metals, etc. Performance can be obtained.
By setting the content of the residual CaMg (CO ₃ ) ₂ phase within the above range, it is possible to achieve better insolubilization of heavy metals and the like.

Such a suitable semi-baked dolomite has a residual CaMg (CO ₃ ) ₂ phase content of 0.4 ≦ x ≦ 35.4 (mass%) in a dolomite fired product analyzed using a Rietveld method by powder X-ray diffraction. It can manufacture by baking so that it may become.
The temperature at which dolomite is calcined is not particularly limited, and can be usually calcined at a temperature at which dolomite is calcined to produce semi-calcined dolomite, for example, 650-1000 ° C. The firing time is not limited as long as the residual CaMg (CO ₃ ) ₂ phase content is 0.4 ≦ x ≦ 35.4 (mass%).

The compounding amount of the semi-baked dolomite is 5 to 30% by mass, preferably 5 to 15% by mass in the insolubilization measure material such as heavy metal.
If it is less than 5% by mass, the insolubilizing ability to lead, fluorine, etc. is reduced, and if it exceeds 30% by mass, the resulting anti-contamination material such as heavy metals is alkaline with a pH of 9 or more, and therefore the pH is not easily lowered by the pH buffering ability. Therefore, a large amount of ferrous sulfate is required, and the essential material blending ratio of amorphous calcium silicate and / or calcium carbonate or polymer material, which guarantees the soil strength improvement ability, is reduced and improved. It will be difficult to improve the solidification performance of the soil.

Furthermore, the pollution control material such as heavy metal of the present invention contains ferrous sulfate as an essential material.
By containing ferrous sulfate, it can be insolubilized more effectively with respect to heavy metals such as arsenic and hexavalent chromium by its high reducing action, and since it is acidic, By adjusting the blending ratio, the soil treated with the pollution control material such as heavy metal of the present invention can be kept neutral.
In addition, ferrous sulfate is presumed to have an effect as an inorganic flocculant, and it may be considered that it has a function of improving the soil hardness by electrically agglomerating fine particles in the soil.

As a compounding quantity of ferrous sulfate, it is 5-45 mass% in insolubilization measures materials, such as a heavy metal, Preferably it is 10-30 mass%.
If it is less than 5%, the reducibility is lowered, the effect of insolubilization to arsenic, hexavalent chromium, etc. is lowered. If it exceeds 45% by mass, the pH tends to be acidic, and the production cost is increased, which is not economical.

The anti-contamination material such as heavy metal of the present invention further contains amorphous calcium silicate and / or calcium carbonate as an essential material.
As the amorphous calcium silicate, any commercially available amorphous calcium silicate can be used. For example, at least one selected from the group consisting of blast furnace slag and steelmaking slag can be preferably used. More preferred is blast furnace slag, and particularly preferred is blast furnace granulated slag.
For example, blast furnace slag, etc. is weakly alkaline with a pH of about 9 to 10, and has latent hydraulic properties and develops strength over the long term. Therefore, it has the effect of improving and improving the solidification performance of soil. It can be particularly preferably used.
Calcium carbonate dissolves calcium and reacts with the aluminum components in the soil to precipitate ettringite-like hydrates, thereby binding the soil particles firmly and promoting agglomeration. Can be obtained.
Amorphous calcium silicate and calcium carbonate can be used alone or in combination. When they are used in combination, use can be designed at an arbitrary ratio.

The blending amount is 50% by mass or more, preferably 60% by mass or more, in the insolubilization measure material such as heavy metal.
If the amount added is less than 50% by mass, the solidification performance of the improved soil is lowered, which is not desirable.
Moreover, although it does not restrict | limit especially about the composition of the slag to be used, Since the thing of gypsum mixing | blending slag mixing accelerates | stimulates hydraulic property, it can be used conveniently.
Moreover, it is suitable that it is a powder form about slag, and a brane specific surface area is 8,000 cm < ² > / g or less, More preferably, it is 3,000-5,000 cm < ² > / g, and solidifies and improves soil. Desirable in terms. Furthermore, in order to suppress elution of heavy metals from the slag itself, it is necessary that the amount of elution and the content of all specific harmful substances contained in the slag itself be lower than the environmental standard value.

The anti-contamination material such as heavy metal of the present invention further contains a polymer material as an essential material, and the polymer material is preferably in a powder form because it needs to absorb water from the soil and react.
As the properties of the polymer material used in the present invention, it is easy to dissolve in cold water, the pH of the aqueous solution is in a neutral region, and since it corresponds to various soils, the effective pH region covers the range of weak acid to weak alkalinity. In addition, it is desirable to use a material that exhibits thickening when dissolved in water.

  As polymer materials, polymer flocculants have the effect of agglomerating fine particles by reacting with moisture in the soil and making the soil easier to tighten, and particles are bonded by reacting with moisture in the soil and thickening. The thickener to be used can be used suitably. As the kind of the organic polymer flocculant, at least one selected from the group consisting of an anionic polymer flocculant, a nonionic polymer flocculant, and a cationic polymer flocculant can be used. It is an anionic polymer flocculant having a neutral solution pH and a high viscosity. As the organic polymer flocculant, at least one selected from the group consisting of polyacrylamide, polyacrylate ester, polyamidine, sodium polyacrylate, polyethylene oxide, sodium acrylate-acrylamide copolymer may be used. Particularly preferred is a polyacrylamide type, which has a high aqueous solution viscosity when dissolved in the same amount of water.

  As the thickener, at least one selected from the group consisting of cellulose derivatives, polyamide derivatives, polyvinyl alcohol derivatives, guar gum, starch, xanthan gum, and propylene glycol can be used. The derivatives are hydroxyethyl methylcellulose (HEMC), hydroxypropylmethylcellulose (HPMC), and methylcellulose (MC).

In addition, the polymer material has a neutral pH, and can further contribute to strength improvement and re-mudging suppression by solidifying the soil by binding fine particles in the soil to become aggregated particles. .
The blending amount is 0.1 to 10% by mass, preferably 1 with respect to the total amount of the semi-baked dolomite, ferrous sulfate, amorphous calcium silicate and / or calcium carbonate. ˜5 mass%.
When it exceeds 10 mass%, cost will become high and it is not economical. In addition, addition of a large amount of organic matter to the soil is not environmentally preferable.

The anti-contamination material such as heavy metal of the present invention, by blending the above-mentioned semi-baked dolomite, ferrous sulfate, amorphous calcium silicate and / or calcium carbonate, and the essential material of the polymer material in the above blending ratio, When mixed with soil, the pH can be neutral (5.8 to 8.6, which is a uniform drainage standard).
Moreover, you may add arbitrary materials for pH adjustments, such as aluminum sulfate and slaked lime, in addition to the said essential content material in the range which does not affect the insolubilization performance of pollution control materials, such as a heavy metal of this invention.

  The anti-contamination material such as heavy metal of the present invention may be any method as long as the semi-baked dolomite, ferrous sulfate, amorphous calcium silicate and / or calcium carbonate, and a polymer material can be mixed uniformly. Can be prepared by mixing.

  The heavy metal pollution control method of the present invention is a method of mixing a heavy metal pollution control material and contaminated soil, but the mixing method is not particularly limited. For example, the heavy metal pollution control material is applied to the soil surface layer. It is possible to apply soil mixing equipment similar to conventional powder insolubilizing materials, such as improvement by heavy machinery having a surface modification performance and mixing equipment with soil.

  In addition, heavy metal and other pollution control materials are desirably used in the form of powder, and as a mixing device with contaminated soil, it is excessive to mix using a backhoe, deep mixing processor, stationary mixer, power blender, etc. And the compounding quantity of countermeasure processing materials, such as a heavy metal with respect to treated soil, fluctuates with the moisture content of soil, the solidification intensity | strength of the required treated soil, etc., and can be designed arbitrarily.

In this way, heavy metals such as heavy metals are brought into contact with contaminated soil from which heavy metals, fluorine, etc. are eluted, so that the heavy metals eluted from the contaminated soil are insolubilized and the solidification performance of the soil and the re-mudging suppression function are improved. Thus, the pH of the treated soil can be kept neutral.
For example, the amount of elution of heavy metals, etc., in the soil is all within the standards for soil elution, measured according to the Soil Contamination Countermeasures Law, and conforms to the Environmental Agency Notification No. 46 (promulgated on August 23, 1991) The pH of the test solution prepared by the method is in the range of 5.8 to 8.6 defined in the uniform drainage standards of the Environment Agency. It can be set to 400 kN / m ² or more as defined in the standard third-grade improved soil, and can be designed to reliably satisfy the environmental standard.

The invention is illustrated by the following examples and comparative examples.
(Preparation of simulated contaminated soil)
Simulated contaminated soil was prepared as follows.
A raw soil having the characteristics shown in Table 1 below was prepared as a raw soil to be used when preparing the simulated contaminated soil.

Next, aqueous solutions in which arsenic, lead, and fluoride reagents were dissolved were prepared.
Specifically, as an aqueous solution containing arsenic, an aqueous solution in which a predetermined amount of sodium arsenite [NaAsO ₂ ] (manufactured by Kanto Chemical Co., Ltd.) is added and dissolved in water is used as an aqueous solution containing lead. An aqueous solution in which a predetermined amount of lead nitrate [Pb (NO ₃ ) ₂ ] (manufactured by Kanto Chemical Co., Ltd.) is added and dissolved in water is sodium fluoride [NaF] (Kanto Chemical Co., Inc.) as an aqueous solution containing fluoride. An aqueous solution prepared by adding a predetermined amount of (made) to water was prepared.

A predetermined amount of each of the obtained arsenic-containing aqueous solution, lead-containing aqueous solution, and fluoride-containing aqueous solution was added to the raw soil, and the mixture was stirred and mixed by a soil mixer so as to be sufficiently mixed at a low speed. The soil adhering to the container of the soil mixer and the paddle was scraped off, and then thoroughly mixed again at a low speed.
Next, each soil was sealed in a polyethylene bag in a room at 20 ° C. and cured for 7 days, and each of three types of simulated contaminated soils of arsenic simulated contaminated soil, lead simulated contaminated soil, and fluorine simulated contaminated soil was prepared.

  For each simulated contaminated soil, prepare a test solution in accordance with the Environmental Agency Notification No. 46 (promulgated on August 23, 1991) and set the concentration of heavy metals, etc. in the test solution to JIS K 0102 “Factory Wastewater Test Method”. Measured in conformity. The measured results of arsenic, lead, and fluorine elution amounts from each simulated contaminated soil are shown in 2 below.

(Raw materials used)
The following materials were used in preparing pollution control materials such as heavy metals.
・ Semi-baked dolomite (powder): Tochigi Prefecture Kuzu production ・ Ferrous sulfate: Sakai Chemical Co. monohydrate powder ・ Amorphous calcium silicate: Nippon Steel & Sumikin Slag Products Co., Ltd. Blast furnace slag fine powder (trade name: SMENT 4000 BRAIN with plaster)
・ Calcium carbonate: Kanto Chemical Co., Ltd., deer first grade powder ・ Polymer material: Polymer flocculant-Made by Hymo Co., Ltd., Thickener-Matsumoto Yushi Seiyaku Co., Ltd. ・ Hemihydrate gypsum: Kanto Chemical Co., Ltd. calcined gypsum powder

  The chemical composition of the above-mentioned semi-baked dolomite (powder): Tokugi Prefecture Katsu Production) was measured in accordance with JIS M 8851: 1983 “Analytical Method of Dolomite”. The results are shown in Table 3 below.

(Heavy metal pollution control materials)
The above-mentioned raw materials used were mixed at the blending ratios shown in Table 4 below to prepare pollution control materials such as heavy metals.
In addition, although the mixing order in particular of each raw material is not restrict | limited, each raw material was mixed simultaneously and each pollution control material, such as each heavy metal, was manufactured. In Table 4, the polymer material is blended in an external proportion with respect to the total mass of amorphous calcium silicate and / or calcium carbonate, semi-baked dolomite, and ferrous sulfate (mass%) ).

(Test example)
Test Example 1: Insolubilization test for heavy metals, etc. To each 1 m ^{3 of the} above-mentioned simulated contaminated soil, 50 kg of each anti-pollution material for heavy metals shown in Table 4 was added and kneaded at a low speed for 2.5 minutes with a soil mixer. The soil adhering to the container and paddle of the soil mixer was scraped off, and again kneaded at a low speed for 2.5 minutes to prepare each test soil.
After preparing the test soil, a test solution was prepared for each test soil after 7 days (age 7 days) by a method based on the Environmental Agency Notification No. 46 (promulgated on August 23, 1991). Based on JIS K 0102 “Factory drainage test method”, arsenic, lead, and fluorine elution amounts were measured.
As Comparative Example 1, arsenic, lead, and fluorine elution amounts were measured in the same manner with respect to each simulated contaminated soil in which countermeasure materials such as heavy metals were not mixed with each simulated contaminated soil.
The results are shown in Table 5.

Also, the pH of the arsenic simulated contaminated soil solution prepared by a method based on Environment Agency Notification No. 46 (promulgated on August 23, 1991) is measured according to JIS Z8802: 2011 “pH measurement method”. did.
These results are shown in Table 5 below.

Test Example 2: Soil solidification test To 1 m ^{3 of the} above arsenic-containing simulated contaminated soil, 50 kg of various anti-pollution materials such as heavy metals shown in Table 4 were added and kneaded at a low speed for 2.5 minutes with a soil mixer. The soil adhering to the container of the soil mixer and the paddle was scraped off, and again kneaded at a low speed for 2.5 minutes to prepare a test soil.
After preparing the test soil, each test soil was filled into 10 cm molds stipulated in JISA 1210: 2009 “Soil compaction test method by tamping” in three layers and sealed at 20 ° C. until the age of 7 days. After curing, the cone index was measured in accordance with JIS A 1228 “Soil compaction test method by tamping”.
The results are shown in Table 5 below.

Test Example 3: Soil re-mudging test To 1 m ^{3 of the} arsenic-containing simulated contaminated soil, 50 kg of various anti-pollution materials such as heavy metals shown in Table 4 were added and kneaded at a low speed for 2.5 minutes with a soil mixer. Thereafter, the soil adhering to the container of the soil mixer and the paddle was scraped off and kneaded again at a low speed for 2.5 minutes to prepare a test soil.
After preparing the test soil, each test soil was filled into 10 cm molds stipulated in JISA 1210: 2009 “Soil compaction test method by tamping” in three layers and sealed at 20 ° C. until the age of 7 days. After curing, it was demolded to obtain a specimen.
The specimen was put into a water tank storing room temperature tap water, and left still for 24 hours in a state where the specimen was completely immersed in water, and the presence or absence of re-mudging was confirmed by visual inspection from how the specimen collapsed (1 Second immersion).
When the initial shape of the specimen was maintained (not re-mudged) and when the specimen was partially collapsed, the specimen was taken out of water and dried at 30 ° C. for 24 hours. Subsequently, the specimen was left to stand for 24 hours in a state where it was completely immersed again in water, and the presence or absence of re-mudging was confirmed by visual observation from the way the specimen collapsed (second immersion).
The results are shown in Table 5 below.

The amount of arsenic, lead, and fluorine elution that was not more than each soil elution amount standard based on the Soil Contamination Countermeasures Law was deemed acceptable (arsenic: 0.01 mg / L, lead: 0.01 mg / L, fluorine: 0 .8 mg / L).
The test solution pH was determined to be within the range of 5.8 to 8.6 defined by the uniform drainage standards of the Environment Agency.
The corn index passed 400 kN / m ² or more as stipulated in the third type improved soil of the soil classification criteria of “Regarding the Soil Use Standard” of the Ministry of Land, Infrastructure, Transport and Tourism.
The re-mudging test was evaluated as ○ when the initial shape of the specimen was maintained, Δ when part of the specimen was broken or cracked, and x when the shape disappeared and became muddy. The above two underwater immersion tests were carried out, and even after the second immersion, the initial shape was maintained, and the specimens that were not collapsed or cracked visually could be accepted.

From Table 5 above, in the examples using the anti-contamination material such as heavy metals including all the semi-calcined dolomite, ferrous sulfate, amorphous calcium silicate and / or calcium carbonate, and polymer material of the present invention, The elution amount of arsenic, lead, and fluorine in the 7-day-old test soil is all within the soil elution amount standard, the test pH is within the uniform drainage standard range, the cone index is 400 kN / m ² or more, and the specimen is It did not re-mud.
In the examples, the corn index value measured by the same method for the lead-containing test soil and the fluorine-containing test soil was a cone index of 400 kN / m ² or more.

About anti-pollution materials C1 and C2 such as heavy metals that do not contain the polymer material of Comparative Examples 2 and 3, although the corn index is higher than the simulated contaminated soil itself of Comparative Example 1, it is less than 400 kN / m ² . The specimen re-mudged by the first immersion in water.
This is because the corn index is improved by the production of ettringite by the reaction of amorphous calcium silicate and sulfate ions, but there is no aggregation of fine particles in the soil because there is no polymer material, so the corn index is increased. It is thought that it became low and the re-mudging suppression effect was not expressed.

As for the anti-contamination material C3 such as heavy metal that does not contain amorphous calcium silicate and / or calcium carbonate and a polymer material shown in Comparative Example 4, the growth of the corn index is comparative because it does not contain a substance with soil solidifying performance. It was almost less than 400 kN / m ² compared with the simulated contaminated soil itself of Example 1. Further, the specimen was re-mudged by the first immersion in water.

Regarding the pollution control material C4 such as heavy metal that does not contain semi-baked dolomite shown in Comparative Example 5, although the pH was neutral, the elution amount of fluorine exceeded the soil elution amount standard.
This is thought to be because there is no physical adsorption to the micropores present in the semi-fired dolomite and a poorly soluble compound is not formed by the reaction of fluoride ions with the semi-fired dolomite component.

About the pollution control material C5, such as a heavy metal which does not contain ferrous sulfate shown in the comparative example 6, pH became 9.3 and alkaline.
The amount of arsenic and lead elution exceeded the soil elution standard.
Arsenic is considered to be because ferrous sulfate is not contained and hardly soluble iron arsenate does not precipitate.
It is thought that lead does not contain sulfates and hardly soluble compounds such as lead sulfate are not produced.

The countermeasure material C6 such as heavy metal shown in Comparative Example 7 includes all of the half-baked dolomite, ferrous sulfate, amorphous calcium silicate and polymer material, but the amount of amorphous calcium silicate is 20% by mass. Since it was small, the soil solidification performance was low, and the corn index was less than 400 kN / m ² . Further, a part of the specimen collapsed by the first immersion in water, and the specimen was re-mudged by the second immersion in water after drying.

About countermeasure material C7, such as a heavy metal shown in the comparative example 8, hemihydrate gypsum reacts with the water | moisture content in soil, it changes to dihydrate gypsum, and a water content ratio falls, but although the corn index became 400 kN / m < ² > or more. , Which does not contain amorphous calcium silicate and / or calcium carbonate, part of the specimen collapses due to dissolution of dihydrate gypsum by the first immersion in water, and the specimen is submerged by the second immersion in water after drying. Re-mudged.

  About countermeasure material C8, such as a heavy metal shown in the comparative example 9, since it is a hemihydrate gypsum simple substance and does not contain an amorphous calcium silicate and / or calcium carbonate, insolubilization performance, solidification performance, and re-mudging suppression effect are based on acceptance criteria. I did not receive it.

The anti-contamination material for heavy metals and the like, and the anti-contamination method for heavy metals using the anti-corrosion material of the present invention can insolubilize heavy metals and halogens efficiently, and solidify the soil and improve the strength while keeping the improved soil neutral. In addition, since it is excellent in re-mudging suppression effect, it can be effectively used for soil modification from which heavy metals and halogens are eluted. For example, it can be effectively applied to the treatment of contaminated soil from which heavy metals generated in large quantities due to excavation work or construction work such as tunnels and dams are eluted, and further, landfill treatment of lake shores and coasts becomes possible.

Claims (5)

  Semi-baked dolomite, ferrous sulfate, amorphous calcium silicate and / or calcium carbonate, and a polymer material as essential components, and amorphous calcium silicate and / or calcium carbonate of 50% by mass or more, semi-baked While containing dolomite in a proportion of 5 to 30% by mass and ferrous sulfate in a proportion of 5 to 45% by mass, the polymer material comprises amorphous calcium silicate and / or calcium carbonate, semi-calcined dolomite, sulfuric acid An anti-pollution material for heavy metals and the like, characterized by containing 0.1 to 10% by mass in an external ratio with respect to the total mass with ferrous iron.   The heavy metal pollution control material according to claim 1, wherein the heavy metal pollution control material is in a powder form. 3. The anti-pollution material for heavy metals and the like according to claim 1 or 2, wherein the semi-fired dolomite has a residual CaMg (CO ₃ ) ₂ phase content in the dolomite fired product analyzed by the Rietveld method by powder X-ray diffraction is 0 4 ≦ x ≦ 35.4 (mass%), a pollution control material such as heavy metals.   4. The anti-contamination material such as heavy metal according to claim 1, wherein the amorphous calcium silicate is at least one selected from the group consisting of blast furnace slag and steelmaking slag, and the polymer material is organic polymer agglomeration. And the organic polymer flocculant is at least selected from the group consisting of polyacrylamide, polyacrylate ester, polyamidine, sodium polyacrylate, polyethylene oxide, and sodium acrylate-acrylamide copolymer. 1 type, The said thickener is at least 1 sort (s) chosen from the group which consists of a cellulose type thickener, a polyamide type thickener, and a polyvinyl alcohol type | system | group thickener, The pollution control material, such as a heavy metal, characterized by the above-mentioned. A heavy metal pollution control method according to any one of claims 1 to 4, wherein the heavy metal pollution control material is mixed with soil.