JP2010120987A - Solidifying agent - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a solidifying agent which is substantially neutral, prevents elution of heavy metals and F and is excellent in work efficiency in solidification treatment of soil. <P>SOLUTION: The solidifying agent for solidification improvement of soil contains steelmaking slag and a solidification accelerator which accelerates solidification. The finely-powdered steelmaking slag 8 obtained by pulverizing slag generated in a steelmaking process 1 at the pulverization step 41 of a solidifying agent production process 4 after an ore dressing process 3 has basicity of 0.8-1.6, a composition containing <0.4% F, 35-65% CaO, 20-55% SiO<SB>2</SB>and 4-9% Al<SB>2</SB>O<SB>3</SB>, and a particle size of 1,700-4,000 Blaine. In the slag 8, elution amount of F is set to be <0.8 mg/L and elution amount of hexavalent Cr is set to be <0.05 mg/L. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a solidifying agent for solidifying and improving soil by mixing with, for example, soft construction soil.

When construction work is performed in low-wetlands or when reclaiming dredged mud from rivers, soft soil is solidified and improved. Conventionally, cement-based solidifying agents have been used as solidifying agents for solidifying and improving soil. Since the cement-based solidifying agent is highly alkaline, rainwater or the like in contact with the soil treated with the solidifying agent flows out as highly alkaline water, which may adversely affect surrounding planting. Some cement-based solidifying agents are mainly blast furnace cement that effectively uses blast furnace slag produced as a byproduct of steel production. In such cement-based solidifying agents using blast furnace cement, heavy metals such as hexavalent Cr (Cr ⁶⁺ ) and selenium (Se) derived from cement materials and fluorine (F) are eluted by rainwater, which adversely affects the surrounding environment. There is a fear.

As one method for solving the problem of high alkali of the cement-based solidifying agent, it has been proposed to contain a neutralizing agent that neutralizes alkali (for example, see Patent Document 1). As another method, for example, a non-cement solidifying agent containing gypsum as a component has been proposed (for example, see Patent Document 2).
JP 2002-282894 A JP 2004-323599 A

  However, even if a high-alkali problem is solved by adding a neutralizing agent to a cement-based solidifying agent whose main material is blast furnace cement, elution of heavy metals and F derived from the cement material cannot be sufficiently prevented. There's a problem. In addition, the non-cement solidifying agent can solve the problem of high alkali and elution of heavy metals, but the solidification reaction proceeds rapidly during construction to improve the solidification of the soil, so the workability during construction is not good. There are problems such as this and high costs.

  An object of the present invention is to provide a solidifying agent which is almost neutral and prevents elution of heavy metals and F, and is excellent in workability during construction for solidifying treatment, in a solidifying agent for solidifying and improving soil.

The present invention provides a solidifying agent for solidifying and improving soil,
Steelmaking slag and a solidification accelerator that promotes solidification of soil,
Steelmaking slag
Basicity (CaO / SiO ₂ ) of 0.8 to 1.6,
Composition, in mass%, (F): less than _{0.4%, (CaO): 35~65} %, (SiO 2): 20~55%, (Al 2 O 3): 4~9%,
The elution amounts of F and hexavalent Cr in water are F: less than 0.8 mg / L, hexavalent Cr: less than 0.05 mg / L,
It is a solidifying agent characterized by having a particle size of 1700 to 4000 branes.

  In the present invention, the solidification accelerator includes at least one of hemihydrate gypsum and a polymer flocculant.

  In the present invention, the solidification accelerator is hemihydrate gypsum, and the content ratio of hemihydrate gypsum in a mixture obtained by mixing the steelmaking slag and hemihydrate gypsum is 20 to 50% by mass. It is characterized by.

  In the present invention, the solidification accelerator is a polymer flocculant, and the content ratio of the polymer flocculant in the mixture obtained by mixing the steelmaking slag and the polymer flocculant is 2 to 10% by mass. It is characterized by being.

  Further, in the present invention, the solidification accelerator is hemihydrate gypsum and polymer flocculant, and hemihydrate gypsum and polymer occupying in a mixture obtained by mixing the steelmaking slag, hemihydrate gypsum and polymer flocculant. The content ratio of the flocculant is characterized by 10 to 50% by mass of hemihydrate gypsum and 2 to 10% by mass of the polymer flocculant.

  Further, in the present invention, the steelmaking slag is a steelmaking slag obtained by recovering a metal from a slag generated in a steelmaking process for melting stainless steel, and pulverizing a massive slag after the metal recovery. And

  According to the present invention, with respect to steelmaking slag, which is a component of the solidifying agent, the solidifying agent can be made almost neutral by adjusting the basicity and composition, and the elution amount of hexavalent Cr and F into water is limited. The safety to the environment can be increased. In addition, by adjusting the particle size of the steelmaking slag, the curability can be satisfactorily exhibited and sufficient soil strength can be expressed. Moreover, while obtaining long-term intensity | strength with steelmaking slag, initial stage intensity | strength with favorable workability | operativity can be expressed by accelerating | stimulating solidification of soil with a solidification promoter.

  Further, according to the present invention, the hemihydrate gypsum and polymer flocculant contained as the solidification accelerator keep the solidification agent almost neutral, and also promote the solidification of the soil to express the initial strength with good workability. To do.

  Further, according to the present invention, by adjusting the content ratio in at least one of hemihydrate gypsum and polymer flocculant as a solidification accelerator, or both solidification agents, handling of soil during solidification treatment construction However, easy soil hardness can be obtained, and workability is improved.

  Further, according to the present invention, the steelmaking slag is obtained by pulverizing massive slag after recovering the metal from the slag generated in the steelmaking process of stainless steel, and uses such a by-product of stainless steel production. Thus, it is possible to obtain a solidifying agent which is excellent in long-term strength of the treated soil, is inexpensive and has excellent versatility. Here, the lump is used to mean including granularity.

The solidification agent which is embodiment of this invention contains steelmaking slag and the solidification promoter which accelerates | stimulates solidification of soil. Steelmaking slag has a basicity (CaO / SiO ₂ ) of 0.8 to 1.6, a composition of mass%, (F): less than 0.4%, (CaO): 35 to 65%, (SiO ₂ ): 20 to 55%, (Al ₂ O ₃ ): 4 to 9%, F and hexavalent Cr were dissolved in water in amounts of F: less than 0.8 mg / L and hexavalent Cr: 0.05 mg / liter, respectively. Less than L, particle size is 1700-4000 branes. Hereinafter, unless otherwise specified, the content ratio representing the composition and the like represents mass%.

Hereinafter, the reasons for limiting the range such as the basicity of the steelmaking slag will be described.
Basicity _(CaO / SiO 2): _0.8~1.6
The basicity of steelmaking slag has a great influence on the desulfurization of molten steel. If the basicity is less than 0.8, a sufficient desulfurization reaction cannot be obtained. When basicity exceeds 1.6, the fluidity | liquidity of steelmaking slag will fall, the contact interface of molten steel and steelmaking slag will reduce, and desulfurization reaction will not be accelerated | stimulated. In order to achieve (F) <0.4%, which will be described later, the amount of fluorite (CaF ₂ ) that has been added for securing the fluidity of slag must be suppressed. Therefore, in order to ensure the fluidity of the steelmaking slag without using fluorite, the basicity needs to be 1.6 or less. Therefore, the basicity is set to 0.8 to 1.6.

(F): Less than 0.4% When steelmaking slag is used as a component of a soil solidifying agent, the F content must satisfy the soil environment standard of less than 0.4%. Limit the use of fluorite that has been used to secure the fluidity of slag in the past, and make it less than 0.4%, which is the allowable amount inevitably mixed from raw materials other than fluorite.

(CaO): 35 to 65%
CaO is an essential component for the desulfurization reaction, and 35% or more is necessary to sufficiently desulfurize the molten steel. When it exceeds 65%, the ratio of CaO to SiO ₂ generated from the raw material and SiO ₂ generated as a deoxidation reaction product by the reducing agent, that is, the basicity increases, and the fluidity of the steelmaking slag is lowered. Therefore, CaO is 35 to 65%.

(SiO ₂ ): 20 to 55%
SiO ₂ is generated from the raw material and also generated as a deoxidation reaction product by a reducing agent. If it is less than 20%, the basicity is increased to lower the fluidity of the steelmaking slag. On the contrary, if it exceeds 55%, the fluidity of the steelmaking slag can be ensured, but the basicity is lowered and a sufficient desulfurization reaction cannot be obtained. Therefore, SiO2 is ₂₀ to 55%.

(Al ₂ O ₃ ): 4 to 9%
Al ₂ O ₃ is a component that is unavoidably mixed from refractory bricks and raw materials. However, Al ₂ O ₃ is necessary as a component that supplements the role of fluorite that has been used in the past in order to ensure the fluidity of slag, and whether the content is too low or too high, The melting point of the slag rises, making it difficult to ensure the fluidity of the slag. Therefore, the the _Al 2 _{O 3 4~9%.}

Elution amount of F: less than 0.8 mg / L and elution amount of hexavalent Cr: less than 0.05 mg / L Steelmaking slag is used as a component of soil solidifying agent, so it is contained in the soil after solidification treatment. Soil environmental standards must be met. In order to satisfy the elution element standard of the soil environment standard, it is necessary that the elution amount of F <0.8 mg / L and the elution amount of hexavalent Cr <0.05 mg / L, respectively.

Particle size: 1700-4000 Blaine Here, the brain is a fineness determined by a specific surface area test defined in Japanese Industrial Standard (JIS) R5201, and its unit is [cm ² / g]. If the particle size is less than 1700, the steelmaking slag particles are coarse and the surface area of the steelmaking slag particles relative to the surface area of the soil particles is insufficient, so that the solidification reaction of the soil cannot be sufficiently expressed. There is no particular reason for limiting the upper limit of the grain size brane value. However, since it takes a long time to make the particle size of the steelmaking slag extremely fine, it is reasonable to set the upper limit to about 4000 in view of industrial productivity. Therefore, the grain size is 1700-4000 brain.

  The solidification accelerator contains at least one of hemihydrate gypsum and polymer flocculant. Steelmaking slag contained in the solidifying agent solidifies and improves the soil due to its self-hardness, and develops long-term strength of the soil. However, since the reaction of steelmaking slag solidifying the soil is slow acting, it takes a long time for the soil treated with steelmaking slag to exhibit sufficient strength. On the other hand, the solidification accelerator has a rapid effect on solidifying the soil and can exhibit initial strength. Therefore, since the solidification promoter can give strength to soft soil during the solidification processing of the soil, handling of the soil can be facilitated and workability can be improved.

  Hemihydrate gypsum is almost neutral and does not become highly alkaline even if it is contained in a solidifying agent. Here, “substantially neutral” means that the pH is in the range of 5.0 to 9.0. Hemihydrate gypsum reacts with moisture in the soil and hardens in a relatively short period of time, and develops initial strength in soft soil. As the polymer flocculant, for example, an acryl chloride polymer or a natural water-soluble polymer calcium salt can be used. These polymer flocculants are almost neutral and do not become highly alkaline even when contained in a solidifying agent. They react with moisture in the soil and harden in a relatively short period of time. Develop initial strength.

  Hereinafter, the reason for limiting the range of the content ratio of either one or both of the hemihydrate gypsum and the polymer flocculant in the solidifying agent will be described. When the solidification accelerator is hemihydrate gypsum, the content ratio of hemihydrate gypsum in the mixture obtained by mixing steelmaking slag and hemihydrate gypsum is 20 to 50%. If it is less than 20%, the initial strength during the solidification treatment of the soil is not sufficient, and the workability improvement effect cannot be sufficiently obtained. On the other hand, if it exceeds 50%, the solidification during the solidification treatment of the soil proceeds rapidly and the initial strength becomes too high, so the workability is rather lowered.

  When the solidification accelerator is a polymer flocculant, the content ratio of the polymer flocculant in the mixture obtained by mixing the steelmaking slag and the polymer flocculant is 2 to 10%. If it is less than 2%, the initial strength at the time of soil solidification is not sufficient, and the workability improvement effect cannot be sufficiently obtained. On the other hand, if it exceeds 10%, the solidification at the time of the solidification treatment of the soil rapidly proceeds and the initial strength becomes too high, so that the workability is deteriorated. In addition, the cost will increase significantly.

  When the solidification accelerator is hemihydrate gypsum and polymer flocculant, the content ratio of hemihydrate gypsum and polymer flocculant in the mixture obtained by mixing steelmaking slag, hemihydrate gypsum and polymer flocculant is The hemihydrate gypsum is 10 to 50%, and the polymer flocculant is 2 to 10%. The reasons for limiting the ranges of the hemihydrate gypsum and the polymer flocculant are the same as when they are contained alone. However, when it contains by composite, it is more preferable that the content rate which added hemihydrate gypsum and the polymer flocculent is 20 to 50%.

  FIG. 1 shows a simplified process for producing a solidifying agent. The steps for producing the solidifying agent include steelmaking step 1 for producing steelmaking slag as a material, cooling step 2 for steelmaking slag, beneficiation step 3 for collecting metal from the generated steelmaking slag, It includes a solidifying agent production step 4 in which massive steelmaking slag is finely pulverized and mixed with a solidification accelerator to produce a solidifying agent.

  As steelmaking slag, the slag generated in the steelmaking process 1 which melts stainless steel is used suitably. Steelmaking slag obtained when melting stainless steel includes slag produced in the process of desulfurizing stainless steel melted in an electric furnace, and secondary refining of the molten stainless steel after desulfurization, such as vacuum degassing There is a slag generated in

  Based on empirical rules regarding the mixing ratio of raw materials and the element distribution ratio between slag and molten steel, the basicity and composition of steelmaking slag are described above by adjusting the type and mixing amount of the slag raw material for each steel type to be melted. It can be made into the limited range. By making the (F) content in the steelmaking slag less than 0.4%, it is possible to realize an elution amount of F <0.8 mg / L. By keeping the basicity low and ensuring the fluidity of the slag, the use of fluorite can be restricted, and the (F) content in the steelmaking slag can be reduced to less than 0.4%. Although the desulfurization reaction is weakened when the basicity is lowered, the molten steel and slag are effectively stirred, and the desulfurization reaction is promoted by increasing the contact frequency and contact interface area between the molten steel and slag. It is possible to achieve sufficient desulfurization in

  The elution amount of hexavalent Cr <0.05 mg / L can be realized as follows. After the desulfurization process in the steelmaking process 1, the slag is subjected to a reduction process. The hexavalent Cr in the slag is reduced to trivalent Cr by the reduction treatment, and the Cr oxide itself is reduced to become metal Cr and moves into the molten steel. Moreover, steelmaking slag may be taken out from an electric furnace or a secondary smelting furnace and subjected to a reduction treatment with a chemical. By such reduction treatment, hexavalent Cr in the steelmaking slag can be reduced, and the elution amount of hexavalent Cr can be made less than 0.05 mg / L. The steelmaking slag after the reduction treatment is taken out from the electric furnace or the secondary smelting furnace into a heat-resistant container called a noropot and cooled in the cooling step 2. After cooling, the steelmaking slag satisfying (F) <0.4% is sent to the beneficiation step 3.

  FIG. 2 shows a process of separating the bullion and the steelmaking slag in the beneficiation process 3. Steelmaking slag contains a relatively large amount of useful metal components. Then, in the beneficiation process 3, in order to reuse as a molten auxiliary material, the metal which is a metal component contained in the steelmaking slag is recovered. The steelmaking slag is crushed to a rough size in the rod mill crushing step 31. The crushed steelmaking slag is sorted into those having a predetermined size or less in the sieving classification process 32, and sent to a wet bullion recovery process. The steelmaking slag that has not passed through the sieve in the sieve classification process 32 is returned to the rod mill crushing process 31 again. The classified steelmaking slag is collected by collecting only the metal 5 in the specific gravity separation process 33 and the magnetic separation process 34. The steelmaking slag from which the metal 5 has been beneficiated is separated into a powdery steelmaking slag 6 and a massive steelmaking slag in a thickener process 35. The massive steelmaking slag is further classified into massive steelmaking slag 7 of about 5 mm in the Akins classification step 36. Powdered steel slag 6 separated by a thickener can be used as a material for the solidifying agent. However, the steelmaking slag 6 that has already been crushed to a powder form in the beneficiation process 3 is often soft among the steelmaking slags, and the reaction has already progressed to some extent due to moisture compared to the bulk slag by wet processing. . Therefore, in order to develop sufficient long-term strength in the soil after the solidification improvement, it is preferable to use the massive steelmaking slag 7 as a material for the solidifying agent.

  Returning to FIG. 1, in the solidifying agent production process 4, the massive steelmaking slag 7 is first pulverized in a roller mill pulverization process 41 so as to become a fine powder having a particle size of 1700 to 4000 branes. The adjustment of the particle size in the roller mill pulverization step 41 is based on the relationship between the pressing force of the roller mill obtained by empirical rules and the particle size of the pulverized slag, and the pulverization conditions are adjusted so that the particle size is in the range of 1700 to 4000 branes. . Next, a gas stream is blown onto the steelmaking slag crushed by the roller mill, and the finely powdered steelmaking slag 8 blown off by the gas stream is classified by the separator and collected by the collector 42. At the time of classification, the pressure and the rotational speed of the separator are adjusted so that only the fine steelmaking slag 8 within the range of 1700 to 4000 branes is guided to the collector 42. A pulverized steelmaking slag 8 and a solidification accelerator 9 containing at least one of hemihydrate gypsum and a polymer flocculant are prepared so as to have a content ratio in the limited range described above. The solidifying agent 9 is produced by mixing the solidifying accelerator 9 with the mixer 33.

(Example)
Examples of the present invention will be described below. In this example, soft soil was solidified with a solidifying agent, and the properties of the treated soil were evaluated. As the solidifying agent of the example used as a test material, the one produced in the process shown in FIG. 1 was used. Table 1 shows the basicity, composition and elution amount of the steelmaking slag used as the material for the solidifying agent of the examples. The particle size of this steelmaking slag was 1800-3850 branes.

Steelmaking slag shown in Table 1 and at least one of hemihydrate gypsum and a polymer flocculant as a solidification accelerator were mixed in a mixer 43 to prepare four types of solidifying agents. These solidifying agents are referred to as Example 1, Example 2, Example 3, and Example 4. In the solidifying agent of Example 1, the solidification accelerator is hemihydrate gypsum. The content ratio of hemihydrate gypsum in the mixture obtained by mixing steelmaking slag and hemihydrate gypsum in Example 1 is 33.3%. In the solidifying agent of Example 2, the solidification accelerator is a polymer flocculant. An acrylic chloride polymer was used as the polymer flocculant of Example 2. The content ratio of the polymer flocculant in the mixture obtained by mixing the steelmaking slag and the polymer flocculant in Example 2 is 2.0%. In the solidifying agent of Example 3, the solidification accelerator is a polymer flocculant. As the polymer flocculant of Example 3, a natural water-soluble polymer calcium salt was used. The content ratio of the polymer flocculant in the mixture obtained by mixing the steelmaking slag and the polymer flocculant in Example 3 is 4.8%. In the solidifying agent of Example 4, the solidification accelerator is hemihydrate gypsum and a polymer flocculant. As the polymer flocculant of Example 4, a natural water-soluble polymer calcium salt was used. The content ratio of hemihydrate gypsum in the mixture obtained by mixing the steelmaking slag and the solidification accelerator in Example 4 is 48.1%, and the content ratio of the polymer flocculant is 3.8%. is there. As a solidifying agent for the comparative example, Portland cement, which is a commercially available cement-based solidifying agent, was used. Table 2 shows the blending amounts of the solidifying agents of Examples and Comparative Examples used for 1 m ³ of the soil to be solidified.

  A soft construction soil was solidified using the solidifying agent of Examples 1 to 3 and the solidifying agent of the comparative example. In addition, the clay was solidified using the solidifying agent of Example 4. About the soil after a solidification process, strength, pH, and the elution amount of various elements were measured.

Hereinafter, methods for measuring strength, pH, and elution amount, which are evaluation indexes, will be described. Regarding the strength, the cone index was measured in accordance with JIS-A1228. The corn index indicates that the larger the value, the higher the strength of the soil. The initial strength was evaluated by measuring the corn index after 1 to 3 days from the solidification treatment. In addition, the cone index was measured until 7 days after the solidification treatment to determine the change in strength over time, and the state of long-term strength development due to steelmaking slag was evaluated. Regarding the relationship between initial strength and workability, for various solidifying agents other than those shown in Table 2, the embedding work was performed after 1 to 3 days after the solidification treatment, and the workability was evaluated based on the experience. The corn index was measured and determined. When the initial strength was 400 to 2000 kN / m ² , the soil was easy to handle and the workability was good. Moreover, about long-term intensity | strength, if it was 800 kN / m < ² > or more, it evaluated that it was permanent strength enough as construction soil.

  About the pH of soil, it measured according to "the pH test method of a soil suspension" prescribed | regulated to Geotechnical Society standard (JGS) T211. When the pH was in the range of 5.0 to 9.0, it was evaluated as being almost neutral. In addition, it is more preferable that the pH satisfies 5.8 to 8.6, which is a drainage standard for “what is drained into public water areas other than sea areas” defined in the Water Pollution Control Law.

  The amount of elution was measured in accordance with Environmental Agency Notification No. 46 “Environmental Standards Concerning Soil Contamination”. The elements whose elution amount was measured were cadmium (Cd), lead (Pb), hexavalent Cr, arsenic (As), total mercury (t.Hg), selenium (Se), fluorine (F) and boron (F). is there. When the elution amount of these elements was below the standard value shown in Environment Agency Notification No. 46, it was evaluated that there was no problem in using the solidifying agent.

The results of measuring the soil corn index are shown in Table 3. In Table 3, a blank column represents that the measurement was not performed, and a column indicated by a horizontal bar (-) represents that the measurement was impossible because the strength was too high. As for the initial strength at the time of 1 to 3 days after the solidification treatment, in Examples 1 to 4, all satisfy the above strength range of good workability. The strength increases with the passage of days after the solidification treatment, and when looking at the strength after 7 days, all of Examples 1 to 4 are over 800 kN / m ² , and sufficient permanent soil strength is obtained. It was. The initial strength is expressed by the solidification accelerator adjusted so that the content ratio is within the above-mentioned limited range. The long-term strength after 7 days is solidified although it takes time to exhibit the solidification reaction. It is expressed by steelmaking slag with excellent strength.

  The measurement results of pH are shown in Table 4. In Table 4, a blank column indicates that no measurement has been performed. The pH of Example 1 to Example 4 is a minimum of 8.17 and a maximum of 8.31 when 7 days have elapsed, satisfies the range of 5.0 to 9.0 evaluated as neutral, and further prevents water pollution. It also satisfies the range of 5.8 to 8.6, which is the wastewater standard of the law. However, in Example 1 and Example 2, the pH at the end of 1 day after the solidification treatment exceeded 9.0 and was slightly alkaline. However, Example 1 satisfied pH 9.0 or less when 2 days passed, and then further decreased with the passage of days, and fully satisfied the range evaluated as neutral when 7 days passed. Value. For Example 2, only the measurement results after the lapse of 3 days and after the lapse of 7 days, but the pH measurement values after the lapse of 3 days and 7 days have the same level as the measurement values of Example 1, It is considered that the same pH transition behavior as in Example 1 is exhibited. Therefore, it is considered that Example 2 becomes neutral at a pH of about 9.0 as in Example 1 when several days have passed after the solidification treatment. On the other hand, the cement-based solidifying agent of the comparative example was a high alkali having a pH of 11.9 after 1 day from the solidification treatment. The cement-based solidifying agent hardly decreased in pH even after the passage of days, and was highly alkaline at pH 11.2 even after 7 days.

  Table 5 shows the measurement results of the elution amount. In Table 5, the column indicated by ND indicates that the elution amount for each element was not more than the detection limit value. In Example 1 and Example 2, although elution of F and B was observed, both were detected amounts below the reference value and there was no problem. In Examples 1 and 2, elements other than F and B were below the detection limit value, and in Examples 3 and 4, all the elements were below the detection limit value. Therefore, from the viewpoint of the elution amount, there is no problem in using Examples 1 to 4 as solidifying agents. In the comparative cementitious solidifying agent, elution of heavy metals and the like was below the standard value.

It is a figure which simplifies and shows the process of manufacturing a solidifying agent. It is a figure which shows the process which separates the ingot and the steelmaking slag in the beneficiation process 3.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Steelmaking process 2 Cooling process 3 Beneficiation process 4 Solidification agent manufacturing process 7 Lump steelmaking slag 8 Fine powder steelmaking slag 9 Solidification promoter 10 Solidification agent

Claims (6)

In the solidifying agent that solidifies and improves the soil,
Steelmaking slag and a solidification accelerator that promotes solidification of soil,
Steelmaking slag
Basicity (CaO / SiO ₂ ) of 0.8 to 1.6,
Composition, in mass%, (F): less than _{0.4%, (CaO): 35~65} %, (SiO 2): 20~55%, (Al 2 O 3): 4~9%,
The elution amounts of F and hexavalent Cr in water are F: less than 0.8 mg / L, hexavalent Cr: less than 0.05 mg / L,
A solidifying agent characterized by having a particle size of 1700-4000 branes. The solidification accelerator is
The solidifying agent according to claim 1, comprising at least one of hemihydrate gypsum and a polymer flocculant. The solidification accelerator is hemihydrate gypsum;
The solidifying agent according to claim 2, wherein the content ratio of hemihydrate gypsum in a mixture obtained by mixing the steelmaking slag and hemihydrate gypsum is 20 to 50% by mass. The solidification accelerator is a polymer flocculant;
The solidifying agent according to claim 2, wherein the content ratio of the polymer flocculant in the mixture obtained by mixing the steelmaking slag and the polymer flocculant is 2 to 10% by mass. The solidification accelerator is hemihydrate gypsum and a polymer flocculant,
The content ratio of hemihydrate gypsum and polymer flocculant in the mixture obtained by mixing steelmaking slag, hemihydrate gypsum and polymer flocculant is 10-50 mass% of hemihydrate gypsum, polymer flocculant The solidifying agent according to claim 2, wherein the content is 2 to 10% by mass. The steelmaking slag is
6. The steelmaking slag obtained by recovering a base metal from a slag generated in a steelmaking process for melting stainless steel, and pulverizing the bulk slag after the recovery of the base metal. Solidifying agent as described in one.

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