JP6904620B1 - Manufacturing method of ground improvement material - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for producing a ground improving material capable of sufficiently insolubilizing harmful substances contained in incinerator ash and effectively improving the strength. SOLUTION: In a method for producing a ground improving material, incinerated ash and an insolubilizing material containing one or more of CaMg (CO3) 2, CaCO3 and MgO are stirred and mixed to obtain an intermediate material. The first step includes a second step of stirring and mixing an intermediate material, a reducing agent containing an acidic sulfate, and water to obtain a granulated and solidified ground improving material. [Selection diagram] None

Description

The present invention relates to a method for producing a ground improving material.

In recent years, there has been a strong demand for reduction and recycling of industrial waste from the viewpoints of preserving the global environment and building an environmentally friendly society. For example, it is being considered to recycle various incinerated ash generated when general waste, sludge, coal, vegetation, etc. are incinerated as ground improvement materials.

Conventionally, in order to reuse incinerator ash as a ground improvement material, incinerator ash is made in order to insolubilize harmful substances such as heavy metals contained in the incineration ash so as not to elute, and to secure the strength required as a ground improvement material. A technique for solidifying grains has been proposed (see Patent Document 1).

Japanese Patent Application No. 2013-233535

However, although the above-mentioned techniques for insolubilizing incinerator ash and granulating and solidifying are known, there are sufficient techniques that can effectively exert both effects by combining incinerator ash insolubilization and granulation and solidification. It could not be said that it was established.

The present invention provides a method for producing a ground improving material capable of sufficiently insolubilizing harmful substances contained in incinerator ash and effectively improving the strength.

In the method for producing a ground improvement material according to one aspect of the present invention, incinerated ash and an insolubilizing material containing one or more of _{CaMg (CO 3} ) ₂ , CaCO _{3 and MgO are stirred and mixed.} Then, the first step of obtaining the intermediate material, the second step of obtaining the ground improvement material which has been granulated and solidified by stirring and mixing the intermediate material, the reducing agent containing an acidic sulfate, and water. including.

In the method for producing the ground improving material, in the second step, the intermediate material and the reducing agent aqueous solution in which the reducing agent and water are mixed may be stirred and mixed.

Further, the incinerator ash may be a wood-based incinerator ash.

Further, in the first step, the incinerator ash, the insolubilizing material, and the solidifying material may be stirred and mixed.

Further, the solidifying material may contain non-washed sand.

According to the above-mentioned method for producing a ground improvement material, it is possible to produce a ground improvement material capable of sufficiently insolubilizing harmful substances contained in incinerator ash and effectively improving the strength.

Hereinafter, embodiments of the present invention will be described.
In the method for producing a ground improving material of the present invention, incinerated ash and an _{insolubilizing material containing one or more of CaMg (CO 3} ) ₂ , CaCO ₃ and MgO are stirred and mixed to prepare an intermediate material. The first step of obtaining, and the second step of obtaining a ground improvement material which has been granulated and solidified by stirring and mixing an intermediate material, a reducing agent containing an acidic sulfate, and water are included.

In the first step, by stirring and mixing the incinerator ash and the insolubilizing material, the (residual) water contained in the incineration ash reacts with the insolubilizing material, and calcium (Ca) contained in the insolubilizing material. And magnesium (Mg) are eluted as ions. The eluted calcium and magnesium ions react with heavy metals and the like, which are harmful substances contained in incineration ash, and precipitate as hydrates. Therefore, harmful substances such as heavy metals contained in incineration ash can be insolubilized.

Next, in the second step, by stirring and mixing the intermediate material, the reducing agent, and water, the insolubilizing material contained in the intermediate material reacts with water, and calcium and magnesium contained in the insolubilizing material are ionized. Elute as. The eluted calcium and magnesium ions react with heavy metals and the like, which are harmful substances contained in incineration ash, and precipitate as hydrates. Therefore, harmful substances such as heavy metals contained in incineration ash can be insolubilized. In the second step, unlike the first step, the above-mentioned hydration reaction is promoted by active water addition, and the insolubilization effect can be further enhanced.

Further, in the second step, the acidic sulfate contained in the reducing agent reacts with water to hydroxylate. Then, the electron ions due to hydroxylation are suspended and the potential is transferred, so that heavy metals and the like, which are harmful substances contained in the incineration ash, are converted into harmless heavy metals (metals that are difficult to elute) and the like. Further, the sulfate bond with a heavy metal or the like to form an insoluble hydrate. This makes it possible to insolubilize harmful substances such as heavy metals contained in incineration ash.

Further, as described above, the insolubilization of harmful substances such as heavy metals contained in the incineration ash can be efficiently performed by the insolubilization by the two steps of the first step and the second step. That is, in the first step, the incinerator is mixed with the incinerator ash, which is generally alkaline, by stirring, so that the incinerator is insolubilized by forming hydrates on the alkaline side. Further, in the second step, a reducing agent containing an acidic sulfate is stirred and mixed to adjust the pH and insolubilize by potential transfer and hydrate formation in a state of shifting from the alkaline side to the neutral region. I do. By insolubilizing by such two steps, the insolubilizing effect can be further enhanced.

Further, by uniformly mixing the incinerator ash and the insolubilizing material in the first step, insolubilization in the first step can be efficiently performed. Further, in the second step, by mixing the reducing agent and water with the intermediate material uniformly mixed in advance in the first step, insolubilization in the second step can be efficiently performed. This makes it possible to efficiently perform insolubilization in two steps.

Further, in the second step, the calcium and magnesium ions eluted from the insolubilizer react with the sulfate ions eluted from the acidic sulfate contained in the reducing agent to hydrate dihydrate gypsum, magnesium hexahydrate and the like. It becomes a substance and precipitates. Therefore, the water content of the incinerator ash can be reduced and the strength improving effect can be effectively exhibited.

In addition, the addition of water in the second step can combine the particles of the incinerator ash to promote agglomeration. As a result, the granulation effect of the incinerator ash can be enhanced, and the incinerator ash can be solidified to improve the strength.

In particular, powdered and granular incinerated ash has the property of granulating near the plastic limit. Therefore, by stirring and mixing in the vicinity of the plastic limit while adding water in the second step, the granulation effect can be enhanced while utilizing the capillary suction action.

In such a granulation step, in the initial stage of granulation immediately after water addition, portions that locally reach the vicinity of the plastic limit are scatteredly generated. In the middle stage of granulation, the scattered single particles are combined with the powder and the single particles around the single particles that have not reached the plastic limit yet by the stirring action. In the late stage of granulation, the water leached from the surface of a single particle binds to another single particle to promote granulation.

Further, the acidic sulfate contained in the reducing agent mixed in the second step is considered to have an effect as an inorganic flocculant. Therefore, the fine particles of the incinerator ash can be electrically aggregated to facilitate agglomeration, and the granulation and solidification effect can be enhanced. As a result, the obtained soil conditioner has the effect of facilitating compaction of the soil.

In the above method for producing a ground improvement material, as the incineration ash used as a raw material for the ground improvement material, for example, waste incineration ash, paper sludge, coal ash, wood incineration ash (wood ash) and the like can be used. Examples of harmful substances contained in incineration ash include heavy metals such as arsenic and hexavalent chromium.

The insolubilizing material mixed in the first step is a material for insolubilizing (preventing elution) harmful substances such as heavy metals contained in incineration ash, and is one of CaMg (CO ₃ ) ₂ , CaCO ₃ and MgO. Includes species or two or more. Examples of the insolubilizing material include _{calcined dolomite containing CaMg (CO 3} ) ₂ , CaCO _{3, and} MgO as main components (including semi-firing dolomite: MgO / CaCO ₃ , lightly calcined dolomite: CaO / MgO, etc.), CaMg (CO). ₃ ) Examples thereof include dolomite-based compounds such as dolomite containing _{2 as a main component, calcium carbonate (CaCO 3} ), magnesium oxide (MgO) and the like. The insolubilizing material may include various insolubilizing materials other than the above-mentioned materials.

Among the above-mentioned insolubilizing materials, in particular, the calcined dolomite formed by calcining dolomite has many pores formed by thermal decomposition represented by _{"CaMg (CO 3} ) ₂ → MgO + CaCO ₃ + CO _{2" when the dolomite is calcined.} Will be done. Therefore, heavy metals and the like contained in the incinerated ash can be efficiently adsorbed in the pores, and the insolubilization effect can be further exhibited.

In the first step, the mixing amount of the incinerator with respect to the incinerator ash can be appropriately adjusted depending on the type of incinerator, etc. For example, when the incinerator ash is 100% by mass, the incinerator is 5 to 15 mass by mass. Can be%.

The reducing agent mixed in the second step is a material that exerts an effect of insolubilizing (preventing elution) harmful substances such as heavy metals contained in incineration ash by a high reducing action, and contains an acidic sulfate. Examples of the acidic sulfate include ferrous sulfate, aluminum sulfate and the like, and one or more of these can be used. As the reducing agent, various reducing agents other than the above-mentioned acidic sulfate may be contained.

For example, when ferrous sulfate is used as the acidic sulfate, ferrous sulfate reacts with water to become iron hydroxide sulfate in the second step. Then, the electron ions due to hydroxylation are suspended and the potential is transferred, so that heavy metals and the like, which are harmful substances contained in the incineration ash, are converted into harmless heavy metals (metals that are difficult to elute) and the like. Further, sulfuric acid and iron combine with heavy metals and the like to form an insoluble hydrate (iron hydroxide sulfate). This makes it possible to insolubilize harmful substances such as heavy metals contained in incineration ash.

In the method for producing the ground improving material, in the second step, the intermediate material and the reducing agent "aqueous solution", which is a mixture of the reducing agent and water, may be mixed and stirred. By mixing the reducing agent as an aqueous solution, water is effectively supplemented, insolubilization by hydrate formation based on the insolubilizer, and potential transfer based on acidic sulfate and insolubilization by hydrate formation are promoted. Therefore, the insolubilization reaction time can be shortened, the step of separately mixing the reducing agent can be omitted, the insolubilization effect in the second step can be further enhanced, and the water content in the reducing agent aqueous solution can be further enhanced. Is also effectively used for granulation and solidification, so that the strength can be further improved.

In the second step, the ratio of the reducing agent in the aqueous solution of the reducing agent can be appropriately adjusted. For example, when the aqueous solution of the reducing agent is 100% by mass, the reducing agent is 1 to 10% by mass (1 to 10% by mass). It can be 10% aqueous solution), preferably 5% by mass (5% aqueous solution).

In the second step, the mixing amount of the reducing agent aqueous solution with respect to the intermediate material can be appropriately adjusted. For example, when the intermediate material is 100% by mass, the reducing agent aqueous solution is 10 to 30% by mass. Can be done.

Further, the incinerator ash may be a wood-based incinerator ash. Wood-based incineration ash is incineration ash such as vegetation ash generated when vegetation is incinerated by biomass power generation or the like. Wood-based incinerator ash has high alkalinity. Therefore, in the first step, insolubilization is performed by hydrate formation on the alkaline side, and in the second step, PH is adjusted with an acidic sulfate to perform potential transfer and insolubilization by hydrate formation in the neutral region. The insolubilization effect of the two steps can be more effectively exhibited.

Further, since the wood-based incinerator ash sufficiently contains calcium oxide (CaO), which is an element of the hydration reaction (for example, about 25% by mass), the granulation and solidification effect can be effectively exhibited. Further, the wood-based incinerator ash generally has a fine particle size and tends to have a strong capillary adhesive force, so that the granulation and solidification effect can be enhanced. Further, since the wood-based incinerator ash _{contains a sufficient amount of silicon dioxide (SiO 2} ) (for example, about 30% by mass), sufficient strength after granulation and solidification can be ensured.

In addition, as incineration ash, wood-based incineration ash, which is incineration ash for plants and trees used in biomass power generation, etc., is effectively used to produce ground improvement materials, thereby promoting recycling (recycling) and recycling. Can contribute to a type society. In addition, since wood-based incineration ash contains a large amount of calcium (Ca), which is an element necessary for plant growth, and silicon (Si), which is an element that assists growth, it was manufactured using wood-based incineration ash. The ground improvement material not only improves the ground, but also promotes the growth of plants and has a greening effect.

Further, in the first step, the incinerator ash, the insolubilizing material, and the solidifying material may be stirred and mixed. By mixing the incinerator with the solidifying material in addition to the insolubilizing material, solidification can be promoted without inhibiting the granulation of the incinerated ash in the second step. That is, it can be efficiently granulated and solidified, and the strength can be improved.

In the first step, the mixing amount of the solidifying material with respect to the incinerated ash can be appropriately adjusted. For example, when the incinerated ash is 100% by mass, the solidifying material can be 1 to 40% by mass. ..

Further, the solidifying material may contain non-washed sand. By using unwashed sand that can be sufficiently mixed with the incinerator ash, the granulation and solidification effect in the second step can be further enhanced, and the strength can be further improved. The solidifying material may include various solidifying materials other than the above-mentioned non-washed sand.

Example:
Hereinafter, the present invention will be described with reference to Examples and compared with Comparative Examples. Here, test specimens of ground improvement materials were prepared by various raw materials and manufacturing methods, and insolubilization tests and solidification tests were conducted on each specimen.

(Raw materials used)
[Incinerator ash]
Wood-based incinerator ash was used as the raw material incinerator ash. The wood-based incineration ash is a fluidized bed boiler incineration ash of wood pellets and PKS (palm palm husks) used in biomass power generation.

[Insolubilizer]
As the insolubilizing material, two types, an alumina-based insolubilizing material and a dolomite-based insolubilizing material, were used. As the alumina-based insolubilizer _{, an inorganic composite containing Al 2} O ₃ as a main component was used. As the dolomite-based insolubilizer, an inorganic composite containing CaO / MgO (light-baked dolomite), which is calcined dolomite, as a main component was used. In the table described later, the alumina-based insolubilizer is described as "alumina-based" and the dromite-based insolubilizer is described as "dromite-based".

[Solid material]
Non-washed sand was used as the solidifying material.

[Reducing agent]
As the reducing agent, ferrous sulfate was used. When mixed as a reducing agent aqueous solution, a ferrous sulfate 5% aqueous solution was used. The ferrous sulfate 5% aqueous solution is an aqueous solution containing 5% by mass of the reducing agent when the reducing agent aqueous solution is 100% by mass. In the table described later, when the reducing agent and water are mixed separately, they are described as "powder", and when they are mixed as a reducing agent aqueous solution, they are described as "aqueous solution".

(Insolubilization test)
For the incinerator ash as a raw material and each test piece, the elution amount of heavy metals, which are harmful substances contained in industrial waste, was measured by the Elution Test of Notification No. 46 of the Environment Agency. The inspection items were cadmium, hexavalent chromium, cyanide, mercury, alkylmercury, selenium, lead, arsenic, fluorine, and boron. The table to be described later shows the reference value (unit: mg / L) of each inspection item.

(Test Example 1)
A test body 11 as a comparative example and a test body 12 as an example of the present invention were prepared and insolubilized.

[Test body 11]
Wood-based incinerator ash (incinerator ash: raw material A), alumina-based insolubilizer (insolubilizer), non-washed sand (solidifying material), powdered ferrous sulfate (reducing) in a kneading mixer (forced twin-screw mixer) Agent) and water were added, and these were stirred and mixed. The mixing amount of the insolubilizing material was 10% by mass when the incinerator ash was 100% by mass, and the mixing amount of the solidifying material was 5% by mass when the incinerating ash was 100% by mass. The mixing amount of the reducing agent is 0.25% by mass when the incinerator ash is 100% by mass, and the mixing amount of water is 100% by mass when the total amount of the incinerator ash, the insolubilizing material and the solidifying material is 100% by mass. It was set to 20% by mass. As a result, a test piece of the ground improvement material was obtained.

[Test body 12]
Wood-based incinerator ash (incinerator ash: raw material A), dolomite-based insolubilizing material (insolubilizing material) and unwashed sand (solidifying material) were put into a kneading mixer, and these were stirred and mixed. The mixing amount of the insolubilizing material was 10% by mass when the incinerator ash was 100% by mass, and the mixing amount of the solidifying material was 5% by mass when the incinerating ash was 100% by mass. As a result, an intermediate material was obtained (primary stirring, first step). The intermediate material was cured for more than half a day.

Next, an intermediate material, powdered ferrous sulfate (reducing agent) and water were put into a kneading mixer, and these were stirred and mixed. Specifically, granulation and solidification were carried out by stirring and mixing while gradually adding ferrous sulfate and water to the intermediate material. The mixing amount of the reducing agent was 0.25% by mass when the incinerator ash was 100% by mass, and the mixing amount of water was 20% by mass when the intermediate material was 100% by mass. As a result, a test piece of the ground improvement material was obtained (secondary stirring, second step).

Table 1 shows the results of the insolubilization test.
The test body 12 uses a dolomite-based insolubilizer and is mixed (first step, second step) in two steps (described as "two steps" in the table) to obtain an alumina-based insolubilizer. Has a higher insolubilizing effect on heavy metals and the like than the test piece 11 which was mixed once. Specifically, the test body 12 has a sufficient insolubilizing effect for various heavy metals and the like, the amount of fluorine and boron eluted is lower than that of the test body 11, and the insolubilizing effect is high. From this, it was found that using a dolomite system as the insolubilizing material and mixing in two steps (first step, second step) is preferable.

(Test Example 2)
A test body 21 as a comparative example and a test body 22 as an example of the present invention were prepared and insolubilized.

[Test body 21]
Wood-based incinerator ash (incinerator ash: raw material B), dolomite-based insolubilizer (insolubilizer), non-washed sand (solidifying material), powdered ferrous sulfate (reducing agent), and water are added to the kneading mixer. , These were stirred and mixed. The mixing amount of the insolubilizing material, the solidifying material, the reducing agent and water is the same as in the preparation of the test body 11 described above. As a result, a test body 21 of the ground improvement material was obtained.

[Test body 22]
Wood-based incinerator ash (incinerator ash: raw material B), dolomite-based insolubilizer (insolubilizer) and non-washed sand (solidified material) were put into a kneading mixer, and these were stirred and mixed. The mixing amount of the insolubilizing material and the solidifying material was the same as in the preparation of the test body 12 described above. As a result, an intermediate material was obtained (primary stirring, first step). The intermediate material was cured for more than half a day.

Next, an intermediate material, powdered ferrous sulfate (reducing agent) and water were put into a kneading mixer, and these were stirred and mixed. Specifically, granulation and solidification were carried out by stirring and mixing while gradually adding powdered ferrous sulfate and water to the intermediate material. The mixing amount of the reducing agent and water was the same as in the preparation of the test body 12 described above. As a result, a test piece 22 of the ground improvement material was obtained (secondary stirring, second step).

Table 2 shows the results of the insolubilization test.
By performing the two-step mixing (first step, second step), the test body 22 has a higher insolubilizing effect of heavy metals and the like than the test body 21 which was mixed at one time. Specifically, the test body 22 has a sufficient insolubilizing effect for various heavy metals and the like, the elution amount of selenium, fluorine and boron is lower than that of the test body 21, and the insolubilizing effect is high. From this, it was found that mixing in two steps (first step, second step) is preferable.

(Test Example 3)
A test body 31 as a comparative example and a test body 32 as an example of the present invention were prepared and insolubilized.

[Test body 31]
Add wood-based incineration ash (incineration ash: raw material C), dolomite-based insolubilizer (insolubilizer), non-washed sand (solidifying material), and ferrous sulfate 5% aqueous solution (reducing agent aqueous solution) into the kneading mixer. These were stirred and mixed. The mixing amount of the insolubilizing material and the solidifying material is the same as in the preparation of the test body 11 described above. The mixing amount of the reducing agent aqueous solution was 20% by mass when the total amount of the incinerator ash, the insolubilizing material and the solidifying material was 100% by mass. As a result, a test piece 31 of the ground improvement material was obtained.

[Test body 32]
Wood-based incinerator ash (incinerator ash: raw material C), dolomite-based insolubilizer (insolubilizer) and non-washed sand (solidified material) were put into a kneading mixer, and these were stirred and mixed. The mixing amount of the insolubilizing material and the solidifying material was the same as in the preparation of the test body 12 described above. As a result, an intermediate material was obtained (primary stirring, first step). The intermediate material was cured for more than half a day.

Next, the intermediate material and the ferrous sulfate 5% aqueous solution (reducing agent aqueous solution) were put into the kneading mixer, and these were stirred and mixed. Specifically, granulation and solidification were carried out by stirring and mixing while gradually adding a 5% aqueous solution of ferrous sulfate to the intermediate material. The mixing amount of the reducing agent aqueous solution was 20% by mass when the intermediate material was 100% by mass. As a result, a test piece 32 of the ground improvement material was obtained (secondary stirring, second step).

Table 3 shows the results of the insolubilization test.
By performing the two-step mixing (first step, second step), the test body 32 has a higher insolubilizing effect of heavy metals and the like than the test body 31 which was mixed at one time. Specifically, the test body 32 has a sufficient insolubilizing effect for various heavy metals and the like, and the elution amount of cadmium, selenium, fluorine and boron is lower than that of the test body 31, and the insolubilizing effect is high. From this, it was found that mixing in two steps (first step, second step) is preferable.

(Test Example 4)
The test body 41 and the test body 42, which are examples of the present invention, were prepared and insolubilized.

[Test body 41]
Wood-based incinerator ash (incinerator ash: raw material D), dolomite-based insolubilizing material (insolubilizing material) and unwashed sand (solidifying material) were put into a kneading mixer, and these were stirred and mixed. The mixing amount of the insolubilizing material and the solidifying material was the same as in the preparation of the test body 12 described above. As a result, an intermediate material was obtained (primary stirring, first step). The intermediate material was cured for more than half a day.

Next, an intermediate material, powdered ferrous sulfate (reducing agent) and water were put into a kneading mixer, and these were stirred and mixed. Specifically, granulation and solidification were carried out by stirring and mixing while gradually adding powdered ferrous sulfate and water to the intermediate material. The mixing amount of the reducing agent and water was the same as in the preparation of the test body 12 described above. As a result, a test piece 41 of the ground improvement material was obtained (secondary stirring, second step).

[Test body 42]
Wood-based incinerator ash (incinerator ash: raw material D), dolomite-based insolubilizing material (insolubilizing material) and unwashed sand (solidifying material) were put into a kneading mixer, and these were stirred and mixed. The mixing amount of the insolubilizing material and the solidifying material was the same as in the preparation of the test body 32 described above. As a result, an intermediate material was obtained (primary stirring, first step). The intermediate material was cured for more than half a day.

Next, the intermediate material and the ferrous sulfate 5% aqueous solution (reducing agent aqueous solution) were put into the kneading mixer, and these were stirred and mixed. Specifically, granulation and solidification were carried out by stirring and mixing while gradually adding a 5% aqueous solution of ferrous sulfate to the intermediate material. The mixing amount of the reducing agent aqueous solution was the same as in the preparation of the test body 32 described above. As a result, a test piece 42 of the ground improvement material was obtained (secondary stirring, second step).

Table 4 shows the results of the insolubilization test.
By adding the reducing agent and water as an aqueous solution of the reducing agent mixed in advance in the second step, the test body 42 has a heavier metal or the like than the test body 41 in which the reducing agent and water are separately added in the second step. Higher insolubilizing effect. Specifically, the test body 41 has a sufficient insolubilizing effect for various heavy metals, etc., but the test body 42 has a lower elution amount of cadmium, fluorine, and boron than the test body 41, and has a higher insolubilizing effect. .. From this, it was found that it is preferable to add the reducing agent and water as a premixed reducing agent aqueous solution in the second step.

(Test Example 5)
Further, a test body 51 as a comparative example and a test body 52 as an example of the present invention were prepared and a solidification test was conducted. The test body 51 was produced in the same manner as the test body 31 described above. Further, the test body 52 was produced by the same method as the above-mentioned test body 32.

In the solidification test, the test piece was filled in three layers in a 10 cm mold specified in JIS A 1210: 2009 "Soil compaction test method by compaction", and sealed and cured at 20 ° C. until the age of 7 days. , JIS A 1228 "Corn index test method for compacted soil" was used to measure the cone index at 7 days of age. ^{As for the corn index, those with 400 kN / m 2} or more specified in the soil classification standard of the Ministry of Land, Infrastructure, Transport and Tourism "Regarding the Soil Utilization Standards for Type 3 Construction" were accepted.

Cone Index, the test body 51 1451kN / ^{m 2,} the test body 52 was 1815kN / ^{m 2.} It was found that the test body 52 had higher strength than the test body 51, which was mixed in one step, by performing the two-step mixing (first step, second step). By mixing the test piece 52 in two stages (first step, second step), the chemical reaction proceeds, the formation of the entry gun facilitates granulation, and the strength is also increased. all right.

It goes without saying that the present invention is not limited to the above-described embodiment, and can be implemented in various embodiments without departing from the present invention. For example, the functions of one component in the above embodiment may be dispersed as a plurality of components, or the functions of the plurality of components may be integrated into one component. Further, a part of the configuration of the above embodiment may be omitted. Further, at least a part of the configuration of the above embodiment may be added or replaced with the configuration of the other embodiment. It should be noted that all aspects included in the technical idea specified from the wording described in the claims are embodiments of the present invention.

Claims (2)

It is a method of manufacturing ground improvement materials.
The first step of obtaining an intermediate material by stirring and mixing the incinerator ash and an _{insolubilizing material containing one or more of CaMg (CO 3} ) ₂ , CaCO _{3 and MgO.}
The obtained and the intermediate material, a reducing agent and an aqueous solution of a mixture of ferrous and water sulphate as a reducing agent, and mixed by stirring, the soil improvement material obtained by granulating solidified by water contained in the aqueous reducing agent solution A method for producing a ground improvement material, which comprises two steps. The method for producing a ground improvement material according to claim 1, wherein the incinerator ash is a wood-based incinerator ash .