JP6538356B2 - Insolubilizing material and insolubilizing slurry - Google Patents

Description

  The present invention relates to an insolubilizer and an insolubilized slurry.

  In recent years, soils have been contaminated with heavy metals such as lead, hexavalent chromium, and arsenic and fluorine (hereinafter, also referred to as "heavy metals and the like") in factories, offices, and industrial waste disposal sites. That is often reported. Thus, when the soil is contaminated with heavy metals and the like, there is a safety and health problem that the contamination spreads to groundwater and affects human bodies and grains. In addition, there is also a problem that when the soil contamination concentration exceeds the environmental standard value, the site can not be used as it is.

Various techniques have been proposed for insolubilizing heavy metals and the like in contaminated soil to suppress elution of the heavy metals and the like from the soil.
For example, Patent Document 1 proposes a heavy metal elution suppressing / solidifying material characterized by comprising magnesium oxide.
Patent Document 2 proposes an insolubilizer characterized in that it comprises a powder of a magnesium-based material that satisfies all of the following conditions (a) to (c).
(A) A calcined product containing magnesium oxide and magnesium carbonate obtained by calcining a mineral containing magnesium carbonate as a main component at 650 to 1,000 ° C. such that a part of the calcined product becomes magnesium hydroxide Be hydrated (b) the oxide equivalent content of calcium is 3.0 mass% or less (c) the ignition loss ratio at 1,000 ° C. is 6 to 30 mass% Patent Document 3 is an insolubilizing agent of a specific harmful substance used in a state of not becoming a strong alkaline region of pH 11 or more with respect to soil, characterized in that an amorphous aluminum compound or a derivative thereof is used as a main component. Insolubilizers for certain harmful substances have been proposed.

Japanese Patent Application Laid-Open No. 2003-117532 JP, 2010-131517, A JP, 2013-227554, A

The insolubilizing material containing magnesium oxide as a main component as described in Patent Documents 1 and 2 described above tends to be weakly alkaline having a pH of 10 or more (see, for example, Table 3 of Patent Document 1), It may adversely affect the surrounding environment.
In addition, as described above, Patent Document 3 describes an insolubilizing material that is used in a state in which a strong alkaline region with a pH of 11 or more does not occur with respect to soil. The insolubilizer can include hemihydrate gypsum as a calcium component. In this case, there is a problem that it solidifies immediately after mixing with water, making it difficult to use as a slurry.

The insolubilizing material is preferably used as a slurry from the viewpoint of improving the permeability of the insolubilizing material to the soil to be treated and improving the effect of suppressing the elution of heavy metals and the like.
However, when the air temperature is high (for example, about 30 ° C.) or the liquid-solid ratio of the slurry containing the insolubilizer (hereinafter, also referred to as insolubilized slurry) is small (for example, 100 mass%), the viscosity of the insolubilized slurry is There was a problem of getting bigger. When the viscosity of the insolubilized slurry is large, the insolubilization slurry and the soil are mixed, and the workability in performing the insolubilization treatment of heavy metals and the like in the soil is deteriorated.
An object of the present invention is that the viscosity after preparation of the insolubilized slurry is small (for example, 6,000 mPa · s or less) even when the air temperature is high or the liquid-solid ratio of the insolubilized slurry is small (e.g., 6,000 mPa · s or less) In the neutral region (e.g., pH 5.8 to 8.6, which is the drainage standard), and further, with regard to heavy metals and the like contained in the soil, an insolubilizing agent having an excellent insolubilizing effect, and It is providing a slurry containing the insolubilizer.

  MEANS TO SOLVE THE PROBLEM As a result of earnestly examining in order to solve the said subject, the present inventors are an acid or its salt, a magnesium oxide containing substance, and an insolubilizing material containing a viscosity modifier, Comprising: The said magnesium oxide containing with respect to the said acid or its salt It is found that the above object can be achieved according to the insolubilizing material in which the amount of the substance and the amount of the viscosity adjusting material with respect to the total amount of the acid or the salt thereof and the magnesium oxide containing material are respectively within specific ranges. , Completed the present invention.

The present invention provides the following [1] to [8].
[1] An insolubilizing agent comprising an acid or a salt thereof, a magnesium oxide-containing substance, and a viscosity adjusting material, wherein the amount of the magnesium oxide-containing substance is 10 to 100 parts by mass with respect to 100 parts by mass of the acid or the salt thereof And the amount of the said viscosity modifier with respect to 100 mass parts of total amounts of the said acid or its salt, and the said magnesium oxide containing material is 10-400 mass parts, The insolubilizer characterized by the above-mentioned.
[2] The content of the acid or its salt is 10 to 65 mass%, the content of the magnesium oxide-containing substance is 7 to 30 mass%, and the viscosity modifier in the total amount (100 mass%) of the material constituting the insolubilizing material The insolubilizing material according to the above [1], wherein the content of is 15 to 83% by mass.
[3] The insolubilizing material according to [1] or [2], wherein the acid or the salt thereof is one or more selected from the group consisting of sulfate, sulfuric acid, hydrochloric acid and acetic acid.
[4] The insolubilizing material according to any one of the above [1] to [3], wherein the magnesium oxide-containing substance contains light-burned magnesia or a partial hydrate thereof.
[5] Any one of the above-mentioned [1] to [4], wherein the viscosity adjusting material is at least one selected from the group consisting of calcium carbonate-containing powder, silica stone powder, shale powder, anhydrous gypsum powder, zeolite powder, and dolomite powder Insolubilized material described in crab.
[6] An insolubilized slurry comprising the insolubilizer according to any one of the above [1] to [5], and water.
[7] The insolubilized slurry according to the above [6], which has a liquid-solid ratio of 100 to 300% by mass.
[8] A method for producing the insolubilized slurry according to the above [6] or [7], wherein the insolubilized slurry has a viscosity of 6,000 mPa · s or less when kneaded. A method of producing an insolubilized slurry, comprising determining the type and amount of each material constituting the material.

According to the insolubilizing material of the present invention, when the slurry containing the insolubilizing material (insolubilizing slurry) is mixed with soil to perform insolubilization treatment of heavy metals and the like in the soil, the temperature is high (for example, about 30 ° C.) And, even when the liquid-solid ratio of the insolubilized slurry is small (for example, 100% by mass), the viscosity at the time of kneading of the insolubilized slurry is suppressed to a low viscosity (for example, 6,000 mPa · s or less) Can.
Moreover, since the pH of the slurry containing the insolubilizing material of the present invention is in the neutral range (for example, pH 5.8 to 8.6 which is the drainage standard), the pH of the soil after the insolubilization treatment is, for example, highly alkaline. Not adversely affecting the surrounding environment.
Furthermore, since the insolubilizer of the present invention has a specific component composition such as a magnesium oxide-containing substance, it has an excellent insolubilizing effect on heavy metals and the like contained in the soil.

The insolubilizing material of the present invention is an insolubilizing material containing an acid or a salt thereof, a magnesium oxide-containing substance, and a viscosity adjusting material, wherein the amount of the magnesium oxide-containing substance is 10 to 100 based on 100 parts by mass of the acid or the salt thereof. The amount of the viscosity adjusting material is 10 to 400 parts by mass with respect to 100 parts by mass of the total amount of the acid or the salt thereof and the magnesium oxide-containing substance.
As said acid or its salt, 1 or more types chosen from the group which consists of a sulfate, a sulfuric acid, hydrochloric acid, an acetic acid etc. are mentioned, for example.
Examples of the sulfate include sulfites such as ammonium sulfite, potassium sulfite, calcium sulfite and sodium sulfite; bisulfites such as potassium bisulfite and sodium bisulfite; thiosulfates such as sodium thiosulfate and potassium thiosulfate; Metal salts such as iron and aluminum sulfate can be mentioned. Among them, ferrous sulfate is preferable from the viewpoint of economy and stability.
The acid or its salt is preferably in the form of powder.

  The content of the acid or its salt is preferably 10 to 65% by mass, more preferably 15 to 60% by mass, particularly preferably 20 to 58% of the total amount (100% by mass) of the material constituting the insolubilizing material of the present invention. It is mass%. If the content rate is 10% by mass or more, elution of heavy metals and the like can be further suppressed. If the content is 65% by mass or less, the pH of the mixed soil can be made more neutral.

Examples of the magnesium oxide-containing substance contained in the insolubilizing material of the present invention include those containing light-burned magnesia or its partial hydrate.
The content of light-burned magnesia or its partial hydrate in the magnesium oxide-containing substance used in the present invention is preferably 70% by mass or more, more preferably 80, from the viewpoint of enhancing the effect of suppressing elution of heavy metals and the like. % By mass or more, more preferably 90% by mass or more, particularly preferably 100% by mass.
Lightly burned magnesia can be obtained by calcining a solid material containing either or both of magnesium carbonate and magnesium hydroxide, preferably at a temperature of 600 to 1,300 ° C.
Examples of the solid material include magnesite, dolomite, brucite, and magnesium hydroxide obtained by precipitating a magnesium component in seawater with an alkali such as slaked lime. These may be lumps or powdery particles.
The firing temperature (heating temperature) is preferably 600 to 1,300 ° C, more preferably 750 to 1,100 ° C, and particularly preferably 800 to 1,000 ° C. It is preferable that the temperature is 600 ° C. or higher in that the efficiency of light-burning magnesia generation is improved. It is preferable at the point which the effect of insolubilization of heavy metals etc. improve that this temperature is 1,300 degrees C or less.
The firing time (heating time) varies depending on the preparation amount of solid material, particle size, etc., but is usually 30 minutes to 5 hours.

The partial hydrate of light-burned magnesia is obtained by grinding light-burned magnesia, and then adding water to the ground product, mixing and stirring, or mixing the ground product under an atmosphere of relative humidity 80% or more for one week It can hold | maintain above and can obtain by partially hydrating light-burning magnesia.
The content of magnesium oxide (MgO) in the light-burned magnesia or its partial hydrate is preferably 65% by mass or more, more preferably from the viewpoint of enhancing the effect of the present invention (suppression of elution of heavy metals etc.) It is 75% by mass or more, more preferably 80% by mass or more, and particularly preferably 85% by mass or more.
The oxide equivalent content of magnesium hydroxide in the partial hydrate of light-burned magnesia is preferably 50% by mass or less, more preferably from the viewpoint of enhancing the effect of the present invention (suppression of elution of heavy metals etc.) Is 20 mass% or less.

The content of components other than magnesium oxide and magnesium hydroxide in light-burned magnesia or its partial hydrate is preferably 7% by mass from the viewpoint of enhancing the effect of the present invention (suppression of elution of heavy metals and the like) The following content is more preferably 5% by mass or less.
The brane specific surface area of the light-burned magnesia or its partial hydrate is preferably from 4,000 to 20,000 cm ² / g, more preferably from the viewpoint of enhancing the effect of the present invention (e.g., suppression of elution of heavy metals). It is 4,500 to 10,000 cm ² / g, particularly preferably 5,000 to 7,000 cm ² / g.

  The amount of the magnesium oxide-containing substance in the insolubilizing material of the present invention is 10 to 100 parts by mass, preferably 20 to 80 parts by mass, more preferably 30 to 60 parts by mass with respect to 100 parts by mass of the acid or its salt. If the amount is less than 10 parts by mass, suppression of elution of heavy metals and the like becomes insufficient. When the amount exceeds 100 parts by mass, the pH of the soil after the insolubilization treatment may be increased to exceed the neutral region.

  The content of the magnesium oxide-containing substance is preferably 7 to 30% by mass, more preferably 8 to 27% by mass, and particularly preferably 9 to 25% of the total amount (100% by mass) of the material constituting the insolubilizing material of the present invention. It is a mass part. When the content is 7% by mass or more, elution of heavy metals and the like can be further suppressed. The pH of the soil after mixing can be made more neutral area (value close to pH 7) as the content rate is 30 mass% or less.

Examples of the viscosity adjusting material contained in the insolubilizing material of the present invention include one or more selected from the group consisting of calcium carbonate-containing powder, silica stone powder, shale powder, anhydrous gypsum powder, zeolite powder, dolomite powder and the like.
Examples of the calcium carbonate-containing powder include industrial calcium carbonate powder, calcium carbonate powder as a reagent, limestone powder, crushed products of shells mainly composed of calcium carbonate, and crushed products of coral.
The calcium carbonate content in the calcium carbonate-containing powder is preferably 80% by mass or more, more preferably 90% by mass or more, and particularly preferably 95% by mass or more.
Examples of anhydrous gypsum powder include natural anhydrous gypsum, and regenerated anhydrous gypsum obtained by heating and dewatering waste gypsum such as waste gypsum board.

The brane specific surface area of the viscosity modifier is preferably 3,000 to 10,000 cm ² / g, more preferably 3,500 to 8,000 cm ² / g. If the value is within the above range, the effect of the present invention (suppression of elution of heavy metals and the like) can be further enhanced.
The amount of viscosity modifier in the insolubilizer of the present invention is 10 to 400 parts by mass, preferably 15 to 300 parts by mass, more preferably 100 parts by mass of the total amount of the acid or the salt thereof and the magnesium oxide-containing substance. Is 20 to 250 parts by mass. If the amount is 10 parts by mass or more, when using the insolubilizing material in the state of a slurry, it is possible to reduce the viscosity at the time of kneading of the slurry. If the amount is 400 parts by mass or less, the suppression of elution of heavy metals and the like is sufficient.

  The content of the viscosity adjusting material is preferably 15 to 83% by mass, more preferably 17 to 80% by mass, and particularly preferably 19 to 75% by mass in the total amount (100% by mass) of the material constituting the insolubilizing agent. is there. When the content is at least 15% by mass, when the insolubilizing material is used in the form of a slurry, the viscosity at the time of kneading of the slurry can be further lowered. If the content rate is 83% by mass or less, the effect of suppressing the elution of heavy metals and the like can be further enhanced.

The insolubilizer of the present invention is preferably mixed with water and used in the form of a slurry. In this case, the permeability of the insolubilizing material to the soil to be treated is improved, and the effect of suppressing the elution of heavy metals and the like is improved.
The liquid-solid ratio of the slurry containing the insolubilizing material (insolubilizing slurry; in other words, the mixture of the insolubilizing material and water) is preferably 100 to 300% by mass, and more preferably 150 to 250% by mass. If the ratio is 100% by mass or more, the permeability to the soil can be further improved, and the viscosity at the time of kneading of the slurry can be further lowered. When the ratio is 300% by mass or less, the effect of suppressing the elution of heavy metals and the like and the workability at the time of mixing with soil are further improved.
In the present specification, “liquid-solid ratio” refers to 100% by mass of solid content in the insolubilized slurry (for example, total amount of acid salt, magnesium oxide-containing substance, and viscosity modifier) in the insolubilized slurry The proportion (mass%) of the mass of the liquid component (water) is said.

The slurry (insolubilized slurry) containing the insolubilizer of the present invention has each material constituting the insolubilized slurry (in particular, each material constituting the insolubilizer so that the viscosity at the time of kneading becomes 6,000 mPa · s or less). It is preferred to determine the type and amount of If the viscosity is 6,000 mPa · s or less, solidification of the insolubilizing material does not start in a short time after kneading, so insolubilizing slurry and soil are mixed to insolubilize heavy metals in the soil, etc. Workability at the time of doing is improved.
The viscosity at the time of kneading of the insolubilized slurry is influenced by the temperature (ambient environmental temperature) as well as the type and amount of each material constituting the insolubilized slurry.
In the present invention, preferably, it is particularly preferably at a temperature of 20 ° C. (ambient environmental temperature) or when the solid-solid ratio of the insolubilized slurry is 100% by mass, more preferably at a temperature of 30 ° C. Even when the solid-solid ratio of the insolubilized slurry is 100% by mass at a temperature of 30 ° C., the viscosity of the insolubilized slurry at the time of kneading can be 6,000 mPa · s or less.

The insolubilizing material of the present invention may further contain a setting retarder and the like.
When the insolubilizing material contains a setting retarder, the workability at the time of insolubilizing treatment of heavy metals and the like in the soil can be further improved.
As the setting retarder, for example, gluconic acid or a salt thereof, citric acid or a salt thereof, glucose and the like can be mentioned.

Examples of the target of the insolubilization treatment using the insolubilizing material of the present invention include soils contaminated with heavy metals such as lead, hexavalent chromium and arsenic, and fluorine (soil containing heavy metals and the like).
Although the compounding quantity (kg) of the insolubilizing material per unit volume (1 m ³ ) of soil containing heavy metals etc. varies depending on the content of heavy metals etc. in the soil, it is preferably 30 kg / m ³ or more, more preferably Is 80 kg / m ³ or more, particularly preferably 120 kg / m ³ or more.
The pH of the soil after the insolubilization treatment is preferably pH 5.8 to 8.6, more preferably 6.0 to 8.0, particularly preferably from the viewpoint that the use of the soil after the treatment is not limited. 6.3 to 7.5.

EXAMPLES Hereinafter, the present invention will be specifically described by way of examples, but the present invention is not limited to these examples.
The materials used are as follows.
(1) ferrous sulfate; manufactured by Kokusan Chemical Co., Ltd., food additives (2) aluminum sulfate; special chemical reagent manufactured by Kanto Chemical Co., Ltd. (3) magnesium oxide containing substance A; light-burned magnesia powder (baked magnesite at 850 ° C. After grinding, the content of magnesium oxide: 95% by mass, Blaine specific surface area: 5,500 cm ² / g)
(4) Magnesium oxide-containing substance B: Partially hydrated powder of light-burned magnesia (having partially hydrated magnesium-containing substance A, magnesium oxide content: 50 to 96.5 mass%, magnesium hydroxide Content rate: 3.5 to 50% by mass)
(5) Viscosity adjusting material A: calcium carbonate-containing powder (limestone powder, specific surface area of brane: 5,500 cm ² / g, content of calcium carbonate: 98.4% by mass, manufactured by Chichibu Lime Industry Co., Ltd.)
(6) Viscosity adjusting material B: Silicate powder (Brain specific surface area: 4,500 cm ² / g, manufactured by Kansai Pacific Industries Co., Ltd.)
(7) Viscosity modifier C; shale powder (Brain specific surface area: 5,000 cm ² / g, Kansai Pacific Industries Co., Ltd.)
(8) Viscosity modifier D; Anhydrite powder (Brain specific surface area: 3,700 cm ² / g, natural anhydrite from Thailand)
(9) Viscosity modifier E: Zeolite powder (Blaine specific surface area: 8,000 cm ² / g, manufactured by Kanesan Kogyo Co., Ltd.)
(10) Viscosity adjusting material F; Dolomite powder (Blaine specific surface area: 4,000 to 6,000 cm ² / g, manufactured by Chichibu Lime Industry Co., Ltd.)
(11) Set retarder; Sodium gluconate (manufactured by Showa Chemical Co., Ltd., primary reagent)

[Examples 1 to 39, Comparative Examples 1 to 2]
The above materials were mixed in the formulations shown in Table 1 to prepare insolubilizers a to n.
Under the environmental temperature shown in Table 2 (Ambient temperature and liquid temperature of water which is a material of the insolubilized slurry), the above insolubilizing agents a to n and water are mixed using a tornado stirrer at a liquid-solid ratio shown in Table 2 Then, an insolubilized slurry was prepared.
The viscosity (“viscosity” in Table 2) and pH of the insolubilized slurry at the time of kneading were measured. The results are shown in Table 2.
The viscosity was measured using a B-type analog viscometer (manufactured by Brookfield). Specifically, the rotational speed of the viscometer was 10 rpm, the value 18 seconds after the start of the measurement was measured, and the obtained measured value was used as the viscosity of the insolubilized slurry.

From Table 2, according to the slurry (Examples 1 to 39) containing the insolubilizing material of the present invention, the viscosity of the insolubilized slurry at the time of kneading can be 6,000 mPa · s or less. In particular, even when the environmental temperature (air temperature) is about 30 ° C. and the liquid-solid ratio is 100 mass% (Examples 1 to 9), the viscosity of the insolubilized slurry at the time of kneading is 6,000 mPa · It can be less than s. Moreover, it is understood that the slurry (Examples 1 to 39) containing the insolubilizing material of the present invention has a neutral pH range.
On the other hand, in Comparative Examples 1 and 2, the pH is 9 or more (Comparative Example 1), or the viscosity at the time of kneading of the insolubilized slurry is 10,000 mPa · s or more (Comparative Example 2).
In addition, since the insolubilizing material of Examples 1-39 and Comparative Examples 1-2 contains magnesium oxide containing substance A or B, it had a sufficient insolubilizing effect.

Claims (4)

An insolubilizing material comprising an acid or a salt thereof, a magnesium oxide-containing substance, and a viscosity modifier, wherein the amount of the magnesium oxide-containing substance is 43 to 100 parts by mass with respect to 100 parts by mass of the acid or the salt thereof An insolubilized slurry containing water and an insolubilizing agent, wherein the amount of the viscosity adjusting material is 233 to 400 parts by mass with respect to 100 parts by mass of the total amount of the acid or the salt thereof and the magnesium oxide-containing substance ,
The content of the acid or its salt is 10 to 21% by mass, the content of the magnesium oxide-containing substance is 7 to 9% by mass, and the viscosity modifier in the total amount (100% by mass) of the material constituting the insolubilizer Content of 70 to 83% by mass,
The above acid or its salt is a sulfate,
The above magnesium oxide-containing substance comprises light-burned magnesia or its partial hydrate,
The viscosity modifier is made of one or more selected from the group consisting of calcium carbonate-containing powder and silica stone powder,
An insolubilized slurry having a liquid-solid ratio of 100 to 250% by mass . The insolubilized slurry according to claim 1, wherein the viscosity adjusting material is silica powder. It is a method for manufacturing the insolubilizing slurry according to claim 1 or 2, and after the respective materials constituting the insolubilizing material are mixed to obtain the insolubilizing material, the ambient temperature is 30 ± 2 ° C. A method of producing an insolubilized slurry comprising: kneading the above insolubilizer and water having a liquid temperature of 30 ± 2 ° C. to obtain an insolubilized slurry. As viscosity during kneading up of the insolubilization slurry is below 6,000 mPa · s, a manufacturing method of insolubilization slurry according to claim 3 to determine the type and amount of each material forming the insoluble slurry.