JP2014042881A - Solidification material for coal ash and method for producing solidified matter using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a solidification material for coal ash where the coal ash mixed with water and the like can be molded into an arbitrary shape and firmly solidified and where the elution of a cation and an anion containing a heavy metal and the like can be suppressed and to provide a method for producing solidified matter which can be used in a wide range of applications such as building and civil engineering materials and the like.SOLUTION: A solidification material for coal ash includes the burned product of a mixture of at least one of Ca(OH)and CaCOand Al(OH). The solidification material for coal ash is blended with the coal ash, water and another raw material if necessary, kneaded and made pasty. Solidified matter can be produced by that a pasty material is molded into an arbitrary shape and solidified.

Description

  The present invention relates to a solidified material for coal ash and a method for producing a solidified product using the same, and specifically, a solidified material for coal ash capable of solidifying coal ash and preventing elution of heavy metal ions and the like. The present invention relates to a method for producing a solidified material that can be widely used as a construction / civil engineering material.

In a thermal power plant using coal as fuel, a large amount of coal ash is generated, and thus, an effective utilization method has been conventionally studied. Most commonly, 5-30 mass% of coal ash is used as cement. The so-called fly ash cement is mixed to a certain degree and used as a raw material for mortar and concrete.
However, coal may contain substances that can cause environmental pollution, such as boron and heavy metals, depending on the type and place of production. These substances can form water-soluble cations, such as iron ions (Fe ³⁺ ) and copper (Cu ²⁺ ), and oxyanions (for example, borate ions (for example, borate ions ( B (OH) ₄ ⁻ ), chromate ions (CrO ₄ ²⁻ ), selenate ions (SeO ₄ ^{2 −} ), molybdate ions (MoO ₄ ^{2 −} ), arsenate ions (AsO ₃ ^{2 −} ), etc.) Some of them form such water-soluble anions, and others, like lead, form both cations (Pb ²⁺ ) and anions (PbO ₂ ²⁻ ).
Cations and anions containing these heavy metals and other substances (hereinafter also referred to as “heavy metal ions”) are mostly attached to coal ash, so when coal ash is used for various purposes. In order to protect the environment, it is necessary to take measures to prevent elution and diffusion of ions subject to regulation among ions such as heavy metals.

Among the coal ash, those not adhering to ions such as heavy metals or those having a small amount of adhesion can be used as raw materials for mortar and concrete as described above. In general, mortar and concrete solidify in a watertight state, so even if ions such as heavy metals are contained in the raw material, if the amount is small, it will be contained in the solidified mortar or concrete and retained, so it will not be eluted to the outside. Can be prevented.
However, when coal ash with a large amount of heavy metal ions is used as it is as a raw material for mortar or concrete, ions such as heavy metals may be eluted from the inside of the mortar or concrete. In the meantime, it is not practical to use after removing ions such as heavy metals from coal ash because the processing cost becomes high. As described above, coal ash having a large amount of ions such as heavy metals does not have a method of use commensurate with economic efficiency, and many of them are disposed of as industrial waste.

Moreover, the technique which manufactures the solidified material from which various substances cannot elute easily using coal ash as a raw material is proposed.
For example, in Patent Document 1, quick lime or slaked lime is added to and mixed with coal ash, and the resulting powder mixture is compressed into a predetermined shape by applying high pressure, and then heated with steam under high temperature and high pressure. A method for producing a solidified body in which heavy metals and the like are hardly eluted by hydrothermal synthesis and further drying at a high temperature is disclosed. And it is supposed that the manufactured solidified body can be used as construction materials, such as a paving material.

  Patent Document 2 discloses a blending step in which water is added to a mixture of coal ash and quicklime to cause a digestion reaction, and a compression synthesis step in which high pressure is applied to the resulting mixture to generate frictional heat and solidify by compression. A method for producing a solidified product in which elution of heavy metals or the like is suppressed is disclosed. The produced solidified product is in the form of small granules or flakes (plate), but its specific use is not disclosed.

JP-A-10-296205 JP 2006-61751 A

However, in the method for producing a solidified body described in Patent Document 1, since powder raw materials such as coal ash and quicklime are mixed with each other, it is difficult to uniformly mix them. Furthermore, the mixed powder mixture is about 10 to 40 MPa. However, since the obtained molded product is only a product obtained by physically compacting the powder, it is fragile and easily collapsed, and it is difficult to mold it into a complicated shape.
Moreover, in order to solidify such a molded product, a hydrothermal synthesis reaction is caused by performing steam heating for about 2 to 24 hours under a high temperature and high pressure of 110 to 200 ° C. using an autoclave. Since it is necessary to infiltrate water vapor to the inside, when the volume of the molded product is large, the production efficiency is extremely poor, and there is a risk of causing poor solidification.
And the implementation of such a method for producing a solidified body also has a problem that expensive and high energy cost facilities such as a large compression molding apparatus and an autoclave are required.

  Moreover, in the manufacturing method of the solidified material of patent document 2, high pressure of about 49-294 MPa is added with respect to the mixture obtained by mixing coal ash and quicklime and adding water, and causing digestion reaction. Thus, it is necessary to generate sufficient frictional heat throughout the mixture in order to generate frictional heat and cause a synthetic reaction by the frictional heat to cause solidification. Therefore, the solidified product that can be produced has a problem that its form is limited to small and thin forms such as granules having a thickness of about 10 mm and flakes having a thickness of about 3 mm.

  Therefore, the present invention can be mixed with coal ash, formed into an arbitrary shape and size, and solidified firmly to solve the problems of the prior art, and heavy metals and other substances can be added to the coal ash. We provide a solidified material for coal ash that can sufficiently suppress the elution of ions such as heavy metals even when many cations and anions containing sucrose are attached, and can be used for a wide range of applications such as construction and civil engineering materials. An object is to provide a method for producing a solidified product.

Of the present invention that achieves the above object, the invention described in claim 1 of the present invention includes a fired product of a mixture of at least one of Ca (OH) ₂ and CaCO ₃ and Al (OH) _3. This is a solidified material for coal ash.

  Similarly, the invention according to claim 2 is the coal ash according to claim 1, wherein in the fired product of the mixture, the molar ratio of Ca to Al (Ca / Al) is in the range of 1 to 10. It is a solidifying material.

  Similarly, the invention described in claim 3 is the coal ash according to claim 1, wherein the calcined product of the mixture has a Ca to Al molar ratio (Ca / Al) in the range of 2 to 5. It is a solidifying material.

  Similarly, the invention described in claim 4 is the solidified material for coal ash according to any one of claims 1 to 3, wherein the baking temperature of the fired product is 600 ° C or higher.

  Similarly, the invention described in claim 5 is the solidified material for coal ash according to any one of claims 1 to 3, characterized in that the firing temperature of the fired product is 800 to 1200 ° C.

  Similarly, the invention according to claim 6 is a mixture of the coal ash solidifying material according to any one of claims 1 to 5 with coal ash, water, and other raw materials as necessary, and kneaded. A method for producing a solidified product, characterized in that the paste-like product is formed into a predetermined shape and solidified.

  Similarly, in the invention described in claim 7, the mass of the fired product included in the coal ash solidified material is 30 to the total mass of the fired product and the coal ash. It mix | blends so that it may become 60 mass%, It is a manufacturing method of the solidified material of Claim 6.

  Similarly, the invention described in claim 8 is the method for producing a solidified product according to claim 6 or 7, wherein the paste-like material is solidified by steam curing at a temperature of 60 ° C. or higher.

According to the solidified material for coal ash of the present invention, a paste-like material having appropriate fluidity can be obtained by blending and kneading coal ash and water. By pouring into a frame and allowing to stand, a solidified product solidified in an arbitrary shape and in a watertight state can be produced. That is, since it can be handled in the same way as general mortar and concrete, workability is extremely high and inexpensive.
In addition, by adjusting the blending amount of coal ash, coal ash and water to be blended during kneading, the viscosity of the paste can be changed arbitrarily, so that it is easy to handle. By adding sand, gravel, etc., it is possible to impart properties that more closely resemble mortar and concrete.

  Furthermore, the solidified material for coal ash of the present invention has a property of adsorbing and insolubilizing cations and anions containing heavy metals and other substances. Therefore, according to the solidified material for coal ash of the present invention, even when a large amount of ions such as heavy metals are attached to the coal ash, for example, the characteristics of adsorbing and insolubilizing ions such as heavy metals and watertight state It is considered that the property of forming a solidified product to contain ions such as heavy metals in the solidified product acts synergistically, and a solidified product having a high effect of suppressing elution of ions such as heavy metals can be produced.

Further, according to the method for producing a solidified product of the present invention, it can be molded into an arbitrary shape and size, has a high compressive strength (N / mm ² ) and is strong, and has a high effect of suppressing the elution of ions such as heavy metals. Things can be easily manufactured.
Therefore, the solidified material obtained by the production method of the present invention is used as a construction / civil engineering material such as a flat plate and curb for road paving, a U-shaped side groove, a parking block for a parking lot, artificial fishing reef, tetrapod (wave-dissipating block), etc. It can be used for a wide range of applications.
In addition, the solidified product obtained by the production method of the present invention is lighter in color than a general gray concrete product and is almost white, so that it is also beautiful in appearance, and by adding various pigments, any color can be obtained. It is possible to enhance the aesthetics by adding a texture and texture.

It is an example of the graph of TG of the mixture of Ca (OH) ₂ and Al (OH) ₃ . It is an example of the XRD pattern of the mixture of Ca (OH) ₂ and Al (OH) ₃ . It is another example of the XRD pattern of the mixture of Ca (OH) ₂ and Al (OH) ₃ . Is an example of a graph of TG of a mixture of CaCO ₃ and Al (OH) _3. Is an example of the XRD pattern of a mixture of CaCO ₃ and Al (OH) _3. It is another example of the XRD pattern of the mixture of CaCO ₃ and Al (OH) ₃ . It is a graph which shows an example of the boron adsorption amount of various baked products. It is a graph which shows the other example of the boron adsorption amount of various baked products. It is a graph which shows an example of the adsorption amount of ^{Cr6 +} of various baked products. It is a graph which shows the other example of the adsorption amount of ^{Cr6 +} of various baked products. It is a graph which shows an example of the adsorption amount of Cr3 ⁺ of various baked products. It is a graph which shows an example of the compressive strength of various solidified material. It is an example of the XRD pattern of various solidified material.

Embodiments of the present invention will be described below. It should be noted that the present invention is not limited to these embodiments unless contrary to the spirit of the present invention.
The solidified material for coal ash of the present invention includes a fired product of a mixture of at least one of Ca (OH) ₂ and CaCO ₃ and Al (OH) _3, and such a mixture includes Ca (OH) ₂ and Al (OH ₃ ), a mixture of CaCO ₃ and Al (OH) ₃ or a mixture of _three of Ca (OH) ₂ , CaCO ₃ and Al (OH) ₃ , and the coal of the present invention. Other materials than Ca (OH) ₂ , CaCO ₃ and Al (OH) ₃ may be included as long as the effects of the solidifying material for ash are not impaired.

Moreover, in the baked product of the mixture, the molar ratio of Ca to Al (Ca / Al) is not particularly limited. For example, when the range is 1 to 10, when solidified product is produced by mixing with coal ash or the like. In addition, a solidified product having a high compressive strength (N / mm ² ) and a high elution suppression effect of ions such as heavy metals can be obtained, and a more preferable range is 2 to 5.
Furthermore, the firing temperature of the fired product is not particularly limited. For example, if it is set to 600 ° C. or higher, when the solidified product is produced by mixing with coal ash or the like, the compression strength is high and the elution control of ions such as heavy metals is suppressed. Since the solidified product with a high effect can be obtained, it is preferable, and it is 800-1200 degreeC more preferably.

The solidified material for coal ash of the present invention includes CaO, Ca (OH) ₂ , Ca ₁₂ Al ₁₄ O ₃₃ , CaAl ₄ O ₇ , CaAl ₂ O ₄ , Ca ₅ Al ₆ O ₁₄ and Ca ₉ Al ₆ O ₁₈ . Contains compounds. These compounds are mainly produced by the chemical reaction of Ca (OH) ₂ and CaCO ₃ with Al (OH) _3, and the amount of these compounds produced is the molar ratio of Ca and Al, the firing temperature, etc. It depends on.
In addition, the solidified material for coal ash of the present invention may contain a substance other than the fired product. For example, the solidified material for coal ash may contain an adsorbent of ions such as other solidified materials and other heavy metals.

Next, a method for producing a solidified product using the solidified material for coal ash of the present invention will be described. First, the solidified material for coal ash of the present invention, coal ash and water are blended in predetermined amounts and kneaded to prepare a paste.
The coal ash used here is sand-like or crushed ash generated when coal is burned in a coal-fired boiler or the like of a thermal power plant, and is also called fly ash or clinker ash. The Japanese industrial standards include standards such as fly ash for concrete and clinker ash, but the coal ash that can be used in the present invention is not limited to these, and non-standard coal ash can be widely used. It is not limited by the type of coal, the production area and the components.

The blending amount of the coal ash solidifying material and the coal ash is not particularly limited. For example, the blending amount of the coal ash solidifying material is the same as that of the calcined product and the coal. It is preferable to be 30 to 60% by mass with respect to the total mass of ash, since a solidified product having high strength and a high effect of suppressing elution of ions such as heavy metals can be produced.
Moreover, although it does not restrict | limit especially about the compounding quantity of water, For example, the compounding quantity of water is 0.6-1.2 (with respect to the sum total of the mass of the said baked material and coal ash contained in the solidification material for coal ash. The mass ratio is preferable because the paste can be prepared to have a viscosity that is easy to handle, such as concrete and mortar, and a solidified product having high strength can be produced.

Furthermore, in preparing the paste-like material, other substances can be blended in addition to the coal ash solidifying material, coal ash and water. For example, if sand, gravel, or the like is blended, it is possible to impart properties closer to mortar or concrete to the paste-like material. Moreover, you may mix | blend another solidification material and the adsorption material of heavy metal ion, and also if various pigments are mix | blended, the solidified material to which arbitrary colors and textures were provided can be manufactured.
As a method of kneading the respective raw materials, as long as the paste-like material to be prepared is small, it may be kneaded by using a tool or the like used when kneading concrete or mortar such as so-called Toro boat and kneaded mulberry. . If the amount of paste is large, it may be kneaded using a general concrete mixer or mortar mixer.

Next, the paste-like material prepared by the above method is molded into a predetermined shape and solidified.
The prepared paste-like material has an appropriate viscosity and fluidity like cement and mortar, so it can be poured into a mold of any shape and molded, and other articles using a trowel, spatula, etc. It can be applied by coating on a structure, or can be molded by injecting gaps or cracks in other articles or structures.
When the paste-like material is poured into a mold and molded, general concrete can be poured into every corner of the mold in the same way, so that it can be molded into a complicated shape. Alternatively, it can be molded by pouring into a large mold.
Thus, the paste-like material molded into an arbitrary shape can be solidified into a watertight state by leaving it as it is at room temperature. However, heating at a temperature of 60 ° C. or higher in the presence of water vapor to cure with water vapor is preferable because it can be solidified more quickly and a solidified product with high strength can be produced.

About the chemical reaction when the solidified material for coal ash of the present invention and coal ash, etc. are high in strength and produce a solidified product having a high elution suppression effect of ions such as heavy metals, the overall picture is not clear. By kneading the coal ash solidifying material, coal ash and water of the present invention, CaO contained in the coal ash solidifying material reacts with water to become Ca (OH) ₂ , which is a compound containing Al and coal ash. It is presumed that when Ca ₃ Al ₂ (SiO ₄ ) (OH) _{8 and the} like are produced by a chemical reaction with SiO ₂ contained in the material, it is solidified into a strong and water-tight state.
Further, since the solidified product is solidified in a watertight state, for example, ions such as heavy metals adhering to the coal ash are contained in the solidified product, and further, the compound (CaO 2, (Ca (OH) ₂ , Ca ₁₂ Al ₁₄ O ₃₃ , CaAl ₄ O ₇ , CaAl ₂ O ₄ , Ca ₅ Al ₆ O _14, Ca ₉ Al ₆ O _18, etc.) adsorb heavy metal ions and insolubilize them. Thus, it is estimated that elution of ions such as heavy metals from the solidified product is suppressed. Note that these estimations do not limit the present invention.

  Examples of the present invention will be described by the following test examples shown in (1) to (21) and the test example summary shown in (22). In addition, this invention is not limited by this Example.

(1) Thermal mass (TG) analysis of Ca (OH) ₂ / Al (OH) ₃ mixture
A mixture of Ca (OH) ₂ / Al (OH) _{3 with} a Ca / Al molar ratio = 5 was heated to 100 ° C. to 1000 ° C. at a temperature rising rate of 10 ° C./min, and a thermal mass spectrometer (product name TG 8101D , Manufactured by Rigaku Corporation), and the mass change was measured. The result is shown in FIG. As shown in the figure, the mass was almost constant up to around 100 to 250 ° C., and then the mass suddenly decreased between 250 and 270 ° C., and then the mass was almost constant between 270 and 390 ° C. . Furthermore, after the mass rapidly decreased between 390 and 440 ° C., the mass gradually decreased between 440 and 660 ° C. Thereafter, the mass was almost constant between 660 and 1000 ° C.

(2) X-ray diffraction (XRD) analysis of Ca (OH) ₂ / Al (OH) ₃ mixtures with different firing temperatures Temperatures (350 ° C, 500 ° C, 800 ° C and 1000 ° C ) at which mass was almost constant in the TG analysis The Ca (OH) ₂ / Al (OH) ₃ mixture was calcined at 0 ° C., and the crystalline compound produced by XRD analysis was identified. The result is shown in FIG. As shown, the detected sharp peak derived from the firing temperature 350 ° C. The Ca (OH) ₂ is, but from 500 ° C. At Ca (OH) ₂ was detected broad peak. Therefore, crystalline Ca (OH) ₂ exists at 350 ° C., and crystalline Ca (OH) ₂ becomes amorphous at 500 ° C. with heating. Furthermore, a slight CaO-derived peak was detected in addition to amorphous Ca (OH) _{2 at} a calcination temperature of 800 ° C. At a higher firing temperature of 1000 ° C., the peak intensity derived from CaO was increased, and at the same time, the peak derived from Ca ₁₂ Al ₁₄ O ₃₃ was clearly detected.

(3) XRD analysis of 1000 ° C calcined mixture of Ca (OH) ₂ / Al (OH) ₃ molar ratios
An X-ray diffractometer (product name: D8 ADVANCE TXS, BRUKER AXS) obtained by firing a Ca (OH) ₂ / Al (OH) ₃ mixture with a Ca / Al molar ratio changed between 0.5 and 15 at 1000 ° C. XRD analysis was performed. The result is shown in FIG. As shown in the figure, at a Ca / Al molar ratio of 0.5 and 1.0, in addition to CaO, Ca ₁₂ Al ₁₄ O ₃₃ is detected as a crystalline compound, and while CaAl ₄ O ₇ and CaAl are low in concentration. ₂ O ₄ was also detected. When the Ca / Al molar ratio was 2 or more, peaks attributed to CaO and Ca ₁₂ Al ₁₄ O ₃₃ were detected, but as the Ca / Al molar ratio increased, the peak intensity of CaO increased, and Ca ₁₂ Al ₁₄ O The peak intensity of ₃₃ decreased. From this, it is considered that the amount of CaO produced increased with the increase of the Ca / Al molar ratio, and the amount of Ca ₁₂ Al ₁₄ O ₃₃ produced decreased.

(4) TG analysis of CaCO ₃ / Al (OH) ₃ mixture
The CaCO ₃ / Al (OH) ₃ mixture having a Ca / Al molar ratio of 5 was heated to 100 ° C. to 1000 ° C. at a temperature rising rate of 10 ° C./min, and the mass change was measured using the same apparatus as described above. The result is shown in FIG. As shown in the figure, it shows a substantially constant mass up to around 100 to 250 ° C., after which the mass rapidly decreases between 250 and 270 ° C., and then gradually decreases between 270 and 600 ° C., Mass decreased rapidly between 600-770 degreeC, and showed the substantially constant mass after that (770-1000 degreeC).

(5) XRD analysis of CaCO ₃ / Al (OH) ₃ mixtures with different firing temperatures Based on the TG analysis results described above, the CaCO ₃ / Al (OH) ₃ mixture was fired at a temperature where the mass was almost constant. XRD analysis was performed using the above-mentioned apparatus. The result is shown in FIG. As shown in the figure, a sharp peak derived from CaCO ₃ present in the raw material was detected at a firing temperature of 350 ° C., and a sharp CaO peak at 800 ° C. and a broad peak of Ca (OH) ₂ with low peak intensity. A peak was detected. Therefore, between at least 350 to 800 ° C., thermal decomposition of _{CaCO 3 (CaCO 3 → CaO +} CO 2) It is estimated that happened. It is presumed that Ca (OH) ₂ was produced by CaO absorbing moisture in the air (CaO + H ₂ O → Ca (OH) ₂ ). Furthermore, at a high calcination temperature of 1000 ° C., in addition to a sharp peak derived from CaO, low intensity peaks derived from Ca ₉ Al ₆ O ₁₈ and Ca ₅ Al ₆ O ₁₄ were observed. In this case, CaO is a main component as a crystalline compound, and Ca ₅ Al ₆ O ₁₄ and Ca ₉ Al ₆ O ₁₈ are contained at a low concentration. The estimation does not limit or limit the present invention.

(6) XRD analysis of 1000 ° C calcined mixture of CaCO ₃ / Al (OH) ₃ molar ratios
A CaCO ₃ / Al (OH) ₃ mixture having a changed Ca / Al molar ratio was calcined at 1000 ° C. and subjected to XRD analysis using the above-mentioned apparatus. The result is shown in FIG. As shown in the figure, in the Ca / Al molar ratio = 0.5, trace amounts of Ca ₅ Al ₆ O ₁₄ , CaAl ₄ O ₇ and CaAl ₂ O ₄ were detected as crystalline compounds in addition to CaO. At a Ca / Al molar ratio of 1.0, trace amounts of Ca ₅ Al ₆ O ₁₄ and CaAl ₂ O ₄ were detected in addition to CaO. At a Ca / Al molar ratio of 1.5 or more, a trace amount of Ca ₅ Al ₆ O ₁₄ was detected in addition to CaO and Ca ₉ Al ₆ O ₁₈ . As the Ca / Al molar ratio increased, the intensity of the peak derived from CaO tended to increase, but the intensity of the peak derived from Ca ₉ Al ₆ O ₁₈ increased as the Ca / Al molar ratio increased. When the Ca / Al molar ratio increases to 3, the peak intensity decreases, and when the Ca / Al molar ratio increases to 10 or higher, no peak derived from Ca ₉ Al ₆ O ₁₈ is observed. . From these facts, the CaO production increases as the Ca / Al molar ratio increases, the Ca ₉ Al ₆ O ₁₈ production reaches its maximum when the Ca / Al molar ratio = 3, and further increases the Ca / Al molar ratio. And the production amount of Ca ₉ Al ₆ O ₁₈ decreases, and it is presumed that it disappeared when the Ca / Al molar ratio was 10 or more. However, the present invention is not limited or limited by the estimation.

(7) Adsorption of boron by various baked products Add 0.5 g of various baked products to 50 mL of boric acid (H ₃ BO ₃ ) aqueous solution (B concentration = 11 mg / L), mix well, and then at room temperature for 1 day. I left it alone. Thereafter, the precipitate in the solution was filtered, and the concentration of boron remaining in the filtrate was measured by ICP plasma emission method. The difference between the initial boron concentration (= 11 mg / L) and the residual boron concentration after the addition of various calcined products was defined as the boron adsorption amount (mg / g-calcined product) of the various calcined products.

Calcination temperature of boron adsorption amount for calcined products of Ca (OH) ₂ / Al (OH) ₃ mixture (Ca / Al = 2 and 5) and CaCO ₃ / Al (OH) ₃ mixture (Ca / Al = 2 and 5) The dependency is shown in FIG. As shown in the figure, the highest boron adsorption amount was shown around 1273 K (about 1000 ° C.) regardless of the Ca / Al molar ratio. Further, FIG. 8 shows the Ca / Al molar ratio dependency of the boron adsorption amount of the Ca (OH) ₂ / Al (OH) ₃ mixture and the CaCO ₃ / Al (OH) ₃ mixture fired at 1273K. As shown in the figure, the maximum boron adsorption amount was shown around the Ca / Al molar ratio = 2-5. From these facts, it can be said that these calcined products show a high boron adsorption amount at a Ca / Al molar ratio of around 2 to 5, and a higher calcining temperature indicates a high boron adsorption amount.

(8) Adsorption of chromium ions (hexavalent chromium) by various calcined products After adding 0.5 g of various calcined products to 50 mL of an aqueous solution (Cr concentration = 51 mg / L) in which chromium oxide (CrO ₃ ) is dissolved, mix well. Left at room temperature for 1 day. Thereafter, the precipitate in the solution was filtered, and the Cr concentration remaining in the filtrate was measured by ICP plasma emission method. The difference between the initial Cr concentration (= 51 mg / L) and the residual Cr concentration after addition of various calcined products was defined as the Cr ⁶⁺ adsorption amount (mg / g-calcined product) of the various calcined products.

Of Cr ⁶⁺ adsorption on calcined products of Ca (OH) ₂ / Al (OH) ₃ mixture (Ca / Al = 2 and 5) and CaCO ₃ / Al (OH) ₃ mixture (Ca / Al = 2 and 5) The firing temperature dependence is shown in FIG. As shown in the figure, the highest Cr ⁶⁺ adsorption amount was shown around 1273 K (about 1000 ° C.) regardless of the Ca / Al molar ratio. In addition, FIG. 10 shows the Ca / Al molar ratio dependence of the Cr ⁶⁺ adsorption amount of the Ca (OH) ₂ / Al (OH) ₃ mixture and the CaCO ₃ / Al (OH) ₃ mixture fired at 1273K. In the same figure, as the adsorption condition, in addition to the case of calcined product / aqueous solution = 0.5 g / 50 mL = 10 g / L, the result in the case of calcined product / aqueous solution = 0.1 g / 50 mL = 2 g / L is also shown. As shown in the figure, the maximum Cr ⁶⁺ adsorption amount = 25.5 mg / g-calcined product was shown when the Ca / Al molar ratio = 2-5. From these ^facts, it was found that these calcined products showed a high Cr ⁶⁺ adsorption amount at a Ca / Al molar ratio of around 2 to 5, and a higher calcining temperature showed a higher Cr ⁶⁺ adsorption amount.

(9) Adsorption of chromium ions (trivalent chromium) by various calcined products After adding 0.5 g of various calcined products to 50 mL of an aqueous solution (Cr concentration = 52 mg / L) in which chromium chloride (CrCl ₃ ) is dissolved, mix well. Left at room temperature for 1 day. Thereafter, the precipitate in the solution was filtered, and the Cr concentration remaining in the filtrate was measured by ICP plasma emission method. The difference between the initial Cr concentration (= 52 mg / L) and the residual Cr concentration after addition of various calcined products was defined as the Cr ³⁺ adsorption amount (mg / g-calcined product) of the various calcined products. FIG. 11 shows the influence of the Ca / Al molar ratio in the raw material on the amount of Cr ³⁺ adsorbed when various fired products are produced.

As shown in the figure, among the calcined products of the Ca (OH) ₂ / Al (OH) ₃ mixture, those calcined at a calcining temperature of 600, 800 and 1000 ° C. are all Ca / Al molar ratio = 0.5-15. In the meantime, the entire amount of Cr ³⁺ added to the solution was adsorbed regardless of the Ca / Al molar ratio, and the maximum amount of Cr ³⁺ adsorbed = 5.2 mg / g-calcined product was shown. It is presumed that the CaCO ₃ / Al (OH) ₃ mixture fired product also shows a high Cr ³⁺ adsorption amount. However, the estimation does not limit or limit the present invention.

(10) Adsorption of ions other than boron and chromium by a calcined product of Ca (OH) ₂ / Al (OH) ₃ mixture (Ca / Al = 5) As shown in Table 1, a predetermined amount of various compounds of 1 mmol / L After adding a predetermined amount of a calcined product (calcining temperature: 1000 ° C.) of a Ca (OH) ₂ / Al (OH) ₃ mixture (Ca / Al = 5) to the aqueous solution of (adsorption target ion source) and mixing well Left at room temperature for 1 day. Thereafter, the precipitate in the solution was filtered, and the concentrations of various ions derived from various compounds remaining in the filtrate were measured by ICP plasma emission method. The difference between the initial concentration of various ions and the concentration of various ions remaining after addition of the calcined product of Ca (OH) ₂ / Al (OH) ₃ mixture (Ca / Al = 5) mg / g-baked product). As shown in Table 1, it was found that the fired product also adsorbs ions other than boron and chromium. In Table 1, the maximum adsorption amount is a theoretical calculation value assuming that all the various ions in the solution are adsorbed.

(11) Adsorption of ions other than boron and chromium by the calcined CaCO ₃ / Al (OH) ₃ mixture (Ca / Al = 5) As shown in Table 2, 1 mmol / L of various compounds (adsorption target) A predetermined amount of a calcined product of CaCO ₃ / Al (OH) ₃ mixture (Ca / Al = 5) (calcination temperature: 1000 ° C.) is added to the aqueous solution of the ion source) and mixed well, and then at room temperature for 1 day. I left it alone. Thereafter, the precipitate in the solution was filtered, and the concentrations of various ions derived from various compounds remaining in the filtrate were measured by ICP plasma emission method. The difference between the initial concentration of various ions and the concentration of various ions remaining after addition of the calcined product of CaCO ₃ / Al (OH) ₃ mixture (Ca / Al = 5) -Fired product). As shown in Table 2, it was found that the fired product also adsorbs ions other than boron and chromium. In Table 2, the maximum adsorption amount is a theoretical calculation value when it is assumed that all the various ions in the solution have been adsorbed.

(12) Compressive strength of various solidified products prepared by blending calcined CaCO ₃ / Al (OH) ₃ mixtures having different Ca / Al molar ratios As shown in Table 3, the Ca / Al molar ratio is 0.5 to 10 The five types of CaCO ₃ / Al (OH) ₃ mixtures varied between the two were fired at 1000 ° C. to obtain five types of fired products. Next, each fired product, coal ash (JIS A6201 type 2 compliant product) and water are blended according to each blending amount (mass ratio) shown in Table 3, and kneaded to prepare five types of pastes. did. Next, after pouring each paste-like product into a molding container (cylindrical shape having a diameter of 50 mm × height of 100 mm), it is sealed in a desiccator with water in the lower part, and the desiccator is heated to 75 ° C. in an electric heater. The mixture was allowed to stand for 3 days in the presence of steam and steam cured to produce five types of solidified specimens.
In addition, the blending amount of water is different for each specimen because, when preparing the paste-like material, kneading while gradually adding water while confirming the state of the paste-like material in order to finish the viscosity to be easy to knead and handle. As a result, there is a difference in the blending amount of water.
Next, the compression strength (N / mm ² ) of each solidified specimen was measured using a compressive strength tester (manufactured by JT Toshi Co., ABM200S) in accordance with JIS A1108. Table 3 shows the measurement results.

From the measurement results shown in Table 3, the solidified product produced by blending a calcined CaCO ₃ / Al (OH) ₃ mixture having a Ca / Al molar ratio in the range of 1 to 10 has a compressive strength of 5.8 N / mm. ^If the Ca / Al molar ratio is in the range of 1 to 5 as high as ² or more, it can be seen that the compressive strength is as high as 8.9 N / mm ² or more.

(13) Compressive strength of various solidified products produced by blending calcined CaCO ₃ / Al (OH) ₃ mixtures with different firing temperatures
The CaCO ₃ / Al (OH) ₃ mixture having a Ca / Al molar ratio of 5 was fired at different temperatures shown in Table 4 to obtain four kinds of fired products. Next, each fired product, coal ash (JIS A6201 type 2 compliant product) and water are blended according to each blending amount (mass ratio) shown in Table 4 and kneaded to prepare four types of pastes. did. Next, after pouring each paste-like product into a molding container (cylindrical shape having a diameter of 50 mm × height of 100 mm), it is sealed in a desiccator with water in the lower part, and the desiccator is heated to 75 ° C. in an electric heater. The mixture was allowed to stand for 3 days in the presence of steam, and steam curing was carried out to produce four types of solid specimens.
In addition, although the blending amount of water differs for each specimen, it depends on the hydration method at the time of preparing the paste-like material as described above. In particular, in this test, the blending amount of water becomes larger as the firing temperature of the fired product becomes higher. It is thought that the increase is due to the fact that the higher the firing temperature, the more hydration components are produced.
Next, the compressive strength was measured by the same method as the said test example (12) about the test body of each solidified material. Table 4 shows the measurement results.

From the measurement results shown in Table 4, the solidified product produced by blending the calcined CaCO ₃ / Al (OH) ₃ mixture having a calcining temperature of 800 to 1200 ° C. has a high compressive strength of 3.6 N / mm ² or more. I understand that.

(14) Compressive strength of various solidified products with different blending amounts such as calcined CaCO ₃ / Al (OH) ₃ mixture Solidified product containing calcined CaCO ₃ / Al (OH) ₃ mixture
The calcined product obtained by calcining a CaCO ₃ / Al (OH) ₃ mixture having a Ca / Al molar ratio of 5 at 1000 ° C., coal ash (JIS A6201 type 2 compliant product), and water are shown in Table 5. Blending was carried out according to the blending amount (mass ratio) shown in each column of 5-a, 5-b, 5-c, and 5-d, and kneaded to prepare four types of pastes. Next, after pouring each paste-like product into a molding container (cylindrical shape having a diameter of 50 mm × height of 100 mm), it is sealed in a desiccator with water in the lower part, and the desiccator is heated to 75 ° C. in an electric heater. The mixture was allowed to stand for 3 days in the presence of steam, and steam curing was carried out to produce four types of solid specimens.
The compression strength of each solidified specimen was measured by the same method as in Test Example (12). The measurement results are shown in the columns of test specimens 5-a, 5-b, 5-c and 5-d in Table 5.

2. Solidified product containing alumina cement Alumina cement (AGC Ceramics, Asahi Alumina Cement No. 1 (AC-1)) and coal ash (JIS
A6201 2 types) and water are blended according to the blending amount (mass ratio) shown in each column of the specimens 5-e, 5-f, 5-g and 5-h in Table 5 and kneaded. Different types of pastes were prepared. Next, after pouring each paste-like product into a molding container (cylindrical shape having a diameter of 50 mm × height of 100 mm), it is sealed in a desiccator with water in the lower part, and the desiccator is heated to 75 ° C. in an electric heater. The mixture was allowed to stand for 3 days in the presence of steam, and steam curing was carried out to produce four types of solid specimens.
The compression strength of each solidified specimen was measured by the same method as in Test Example (12). The measurement results are shown in the columns of test specimens 5-e, 5-f, 5-g and 5-h in Table 5.

3. Solidified material blended with Portland cement Portland cement, coal ash (JIS A6201 type 2 compliant product) and water are shown in each column of specimens 5-i, 5-j, 5-k and 5-l in Table 5. They were blended according to the blending amount (mass ratio) and kneaded to prepare four types of pastes. Next, after pouring each paste-like product into a molding container (cylindrical shape having a diameter of 50 mm × height of 100 mm), it is sealed in a desiccator with water in the lower part, and the desiccator is heated to 75 ° C. in an electric heater. The mixture was allowed to stand for 3 days in the presence of steam, and steam curing was carried out to produce four types of solid specimens.
The compression strength of each solidified specimen was measured by the same method as in Test Example (12). The measurement results are shown in each column of the test specimens 5-i, 5-j, 5-k and 5-l in Table 5.
In addition, FIG. 12 represents the description content of Table 5 with the graph.

From Table 5 and FIG. 12, the solidified material blended with the calcined CaCO ₃ / Al (OH) ₃ mixture has higher compressive strength than the solidified material blended with alumina cement or Portland cement, regardless of the blending amount. I understand that. In particular, a solidified product (test bodies 5-a to 5-d) in which the blended amount of the fired product is adjusted to 30 to 60% by mass with respect to the total blended amount of the fired product and coal ash is alumina cement or Portland cement. It can be seen that the compressive strength is remarkably higher than that of the solidified product containing the surfactant.

(15) XRD analysis of various solidified products XRD analysis was performed on the test pieces 5-c, 5-g, and 5-k of the solidified products shown in Table 5 using the X-ray diffraction apparatus. The result is shown in FIG. The specimens 5-c, 5-g, and 5-k correspond to (a), (b), and (c) in FIG.
As shown in the figure, from the solidified product ((a), 5-c) containing the calcined CaCO ₃ / Al (OH) ₃ mixture, Ca (OH) ₂ and Ca ₃ Al ₂ (SiO ₄ ) (OH) ₈ was detected, but these compounds were not detected from the solidified product containing alumina cement ((b), 5-g) and the solidified product containing Portland cement ((c), 5-k). It was. Therefore, the burned material of CaCO ₃ / Al (OH) ₃ mixture, the may form a high solidified product compressive strength than alumina cement and Portland cement, for example, CaCO ₃ / Al (OH) ₃ the calcined product of the mixture By mixing the coal ash and water, CaO contained in the fired product reacts with water to become Ca (OH) ₂ , which chemically reacts with the compound containing Al and SiO ₂ contained in the coal ash. This is presumed to be due to the formation of Ca ₃ Al ₂ (SiO ₄ ) (OH) ₈ or the like. Note that such estimation does not limit the present invention.

(16) Compressive strength of solidified material containing sand instead of coal ash
A calcined product obtained by calcining a CaCO ₃ / Al (OH) ₃ mixture having a Ca / Al molar ratio = 5 at 1000 ° C., sand (JIS R5201 standard sand for cement strength test, Cement Association) and water Were mixed at a blending amount of 100: 100: 124 (mass ratio) and kneaded to prepare a paste. Next, the paste-like material is poured into a molding container (cylindrical shape with a diameter of 50 mm and a height of 100 mm), and then sealed in a desiccator with water in the lower part, and the desiccator is placed in an electric heater heated to 75 ° C. Then, the mixture was allowed to stand for 3 days in the presence of water vapor to cure the water vapor to produce a solidified specimen.
When the compressive strength of the obtained solid specimen was measured by the same method as in Test Example (12), the compressive strength was as low as 0.1 N / mm ² and was brittle and easily collapsed.

(17) Compressive strength of various solidified products containing different types of coal ash
A calcined product obtained by calcining a CaCO ₃ / Al (OH) ₃ mixture with a Ca / Al molar ratio = 5 at 1000 ° C., three types of coal ash (compliance with JIS A6201, Type 1, Type 2 and Type 4), and Water was blended at a ratio of 100: 100: 149 (mass ratio) and kneaded to prepare three types of paste. Next, each paste-like material is poured into a molding container (a cylindrical shape with a diameter of 50 mm and a height of 100 mm), and then sealed in a desiccator with water in the lower part, and the desiccator is heated to 75 ° C. The mixture was allowed to stand for 3 days in the presence of water vapor, and then steam-cured to produce three types of solidified specimens.
The three types of coal ash used have different particle sizes, etc., and when mixed with concrete, the compression strength after solidification is generally the highest in type 1, and decreases in the order of type 2 and type 4. Has been.
Next, the compressive strength of the obtained solidified specimen was measured by the same method as in Test Example (12). Table 6 shows the measurement results.

From the measurement results shown in Table 6, according to the calcined product of the CaCO ₃ / Al (OH) ₃ mixture, a solidified product having high compressive strength can be produced regardless of the type of coal ash. It turns out that the compressive strength of a solidified substance becomes high when the coal ash of this is mix | blended.

(18) Compressive strength of various solidified products with different curing conditions
A calcined product obtained by calcining a CaCO ₃ / Al (OH) ₃ mixture having a Ca / Al molar ratio = 5 at 1000 ° C., coal ash (JIS A6201 type 2 compatible product) and water are each 100: 100: The mixture was blended at a ratio of 154 (mass ratio) and kneaded to prepare a paste. Next, after pouring the obtained paste-like material into four molding containers (cylindrical shape having a diameter of 50 mm × height of 100 mm), a desiccator in which water is placed in the lower portion of the molding container containing these paste-like materials. Sealed inside and placed in an electric heater heated to 40 ° C, 60 ° C, 75 ° C and 90 ° C together with the desiccator and allowed to stand for 3 days in the presence of water vapor for steam curing, 7-a shown in Table 7 4 kinds of solidified specimens of 7-d were produced.

About each obtained test body, when compressive strength was measured by the same method as the said test example (12), 7-b, 7-c, and 7- which are test bodies which were cured and manufactured in the range of 60 degreeC or more d showed a high compressive strength of about 9 N / mm ² or more.

A calcined product obtained by calcining a CaCO ₃ / Al (OH) ₃ mixture having a Ca / Al molar ratio of 5 at 1000 ° C., coal ash (JIS A6201 type 2 compliant product) and water are used in 100: 100: 154. (Mass ratio) or 100: 100: 172 (mass ratio) were blended and kneaded to prepare two types of paste. Next, after pouring each of the two types of pastes obtained into four molding containers (cylindrical shape with a diameter of 50 mm and a height of 100 mm), these were put in a plastic bag and sealed, as shown in Table 8. Eight types of solidified specimens from 8-a to 8-h were produced by leaving them in the room (room temperature: about 25 ° C.) for each predetermined period.

The compressive strength of each of the obtained specimens was measured by the same method as in Test Example (12). As shown in Table 8, it was found that the compressive strength increased almost in proportion to the number of days in the standing period.

(19) Suppression of elution of ions such as heavy metals by various solidified products containing calcined CaCO ₃ / Al (OH) ₃ mixture By the following method, coal ash or the like to which oxo acid salts containing heavy metals are adhered is blended. Various solidified products were manufactured, and the elution amount of ions such as heavy metals from these solidified products was measured.
1. Preparation of coal ash to which oxo acid salts containing heavy metals are attached Coal ash (JIS
A6201 two types of compatible products) are sprayed with various aqueous oxo acid salts in which CrO ₃ , H ₃ BO ₃ , Na ₂ HAsO ₄ · 7H ₂ O and Na ₂ SeO ₄ are dissolved and dried. Coal ash with oxo acid salt attached was prepared. As shown in Table 9, the adhesion amount of the oxoacid salt was changed between 0.1 to 50 mmol / 100 g-coal ash to obtain four types of coal ash having different adhesion amounts.

2. Production of solidified product The four types of coal ash obtained and the calcined product and water obtained by calcining a CaCO ₃ / Al (OH) ₃ mixture with a Ca / Al molar ratio = 5 at 1000 ° C. Four kinds of pastes were prepared by blending according to the blending amounts (mass ratio) shown in the respective columns of the test specimens 9-b, 9-d, 9-f and 9-h. In addition, calcined product obtained by calcining coal ash (JIS A6201 type 2 compliant product) without adhering oxo acid salt and CaCO ₃ / Al (OH) ₃ mixture with Ca / Al molar ratio = 5 at 1000 ° C. And water were blended according to the blending amount (mass ratio) shown in the column 9-j of Table 9 and kneaded to prepare a paste.
After pouring these five kinds of pastes into a molding container (cylindrical shape with a diameter of 50 mm and a height of 100 mm), they were sealed in a desiccator with water in the lower part, and the desiccator was heated to 75 ° C. And cured by steaming in the presence of water vapor for 3 days to produce 5 types of solidified specimens.

3. Measurement of elution amount of ions such as heavy metals The obtained 5 kinds of solidified products were pulverized and sieved to obtain pulverized products having a particle size of 2 mm or less. Next, 100 g of each pulverized product was suspended in 1 L of deionized water, shaken for 6 hours, and then filtered. The concentrations of B, As, and Se contained in the filtrate were determined using an ICP emission analyzer (Seiko). It was measured using a nanotechnology company, product number SPS3100). Further, the concentration of Cr (hexavalent chromium) was measured by an absorptiometer (manufactured by Hitachi, Ltd., product number U-2000) by an absorptiometry shown in a factory drainage test method (JIS K0102). The measurement results are shown in the columns of test specimens 9-b, 9-d, 9-f, 9-h and 9-j in Table 9.
In addition, 100 g of each coal ash is suspended in 1 L of deionized water and the mixture is shaken for 6 hours with respect to the coal ash to which the four types of oxo acid salts are attached and the coal ash to which no oxo acid salt is attached. After filtration, each concentration of B, As, Se and Cr (hexavalent chromium) contained in the filtrate was measured by the same method as described above. The measurement results are shown in the columns of test specimens 9-a, 9-c, 9-e, 9-g and 9-i in Table 9.

From the measurement results shown in Table 9, the solidified product containing the calcined product of the CaCO ₃ / Al (OH) ₃ mixture can sufficiently suppress the elution of ions such as heavy metals adhering to the coal ash and mixed in the solidified product. (Specimens 9-b, 9-d, 9-f, 9-h and 9-j). In particular, even when the concentration of ions such as heavy metals adhering to coal ash is very high (specimens 9-b and 9-d), it shows excellent elution suppression effects, and As and Cr (hexavalent chromium) It can be seen that the elution inhibitory effect on is extremely high.

(20) Suppression of elution of ions such as heavy metals by solidified material containing cement By the following method, coal ash to which oxo acid salt containing heavy metal etc. is adhered and cement are mixed to produce two types of solidified materials, The amount of elution of ions such as heavy metals from these solidified products was measured.
1. Preparation of coal ash to which oxo acid salt containing heavy metal and the like was attached By using the same method as in the test example (19), various oxo acid salts (CrO ₃ , H ₃ BO ₃ , Na ₂ HAsO ₄ · 7H ₂ O And Na ₂ SeO ₄ ) at a rate of 10 mmol / 100 g-coal ash was prepared.

2. Manufacture of solidified material The blended amount (mass) shown in each column of the specimens 10-a and 10-b in Table 10 is the coal ash to which the obtained oxo acid salt is adhered, alumina cement or Portland cement and water, respectively. Ratio) and kneaded to prepare two types of paste. Next, each of these pastes was poured into molding containers (cylindrical shape with a diameter of 50 mm and a height of 100 mm), and then sealed in a desiccator with water in the lower part, and the desiccator was heated to 75 ° C. It was placed in a vessel and allowed to stand for 3 days in the presence of water vapor to cure the water vapor to produce two types of solidified specimens.

3. Measurement of elution amount of ions such as heavy metals The obtained two kinds of solidified products were pulverized and sieved to obtain pulverized products having a particle size of 2 mm or less. Next, 100 g of each pulverized product is suspended in 1 liter of deionized water, shaken for 6 hours, and then filtered. Each concentration of B, As, Se, and Cr (hexavalent chromium) contained in the filtrate is determined. The measurement was performed by the same method as in Test Example (19). The measurement results are shown in each column of the test specimens 10-a and 10-b in Table 10.
Table 10 also shows the measurement results of the specimens 9-c and 9-d obtained in the test example (19).

From the measurement results shown in Table 10, the solidified product blended with alumina cement or Portland cement can suppress the elution of ions such as heavy metals adhering to the coal ash and mixed in the solidified product to some extent, but the effect is CaCO ₃ / It can be seen that it is lower than the solidified product containing the burned product of the Al (OH) ₃ mixture.
The reason for this difference in effect is that the solidified product blended with the calcined CaCO ₃ / Al (OH) ₃ mixture forms a watertight solidified product like various cements, resulting in heavy metal ions, etc. It is presumed that this is because it has the property of adsorbing and insolubilizing ions such as heavy metals unlike various cements. Note that such estimation does not limit the present invention.

(21) Compressive strength of solidified product prepared by blending calcined Ca (OH) ₂ / Al (OH) ₃ mixture
A Ca (OH) ₂ / Al (OH) ₃ mixture having a Ca / Al molar ratio of 5 was fired at 1000 ° C. to obtain a fired product. Next, the obtained calcined product, coal ash (JIS A6201 type 2 compatible product) and water were blended at a blending amount of 100: 100: 160 (mass ratio) and kneaded to prepare a paste. Next, the paste-like material is poured into a molding container (cylindrical shape with a diameter of 50 mm and a height of 100 mm), and then sealed in a desiccator with water in the lower part, and the desiccator is placed in an electric heater heated to 75 ° C. Then, the mixture was allowed to stand for 3 days in the presence of water vapor to cure the water vapor to produce a solidified specimen.
When the compressive strength of the obtained solidified specimen was measured by the same method as in Test Example (12), the compressive strength was as high as 6.9 N / mm ² .

(22) From the general test examples (1) to (6) of the test examples (1) to (21), the present invention includes a calcined product of a mixture of Ca (OH) ₂ or CaCO ₃ and Al (OH) ₃ . The solidified material for coal ash is CaO
It can be understood that compounds such as Ca (OH) ₂ , Ca ₁₂ Al ₁₄ O ₃₃ , CaAl ₄ O ₇ , CaAl ₂ O ₄ , Ca ₅ Al ₆ O _14, and Ca ₉ Al ₆ O ₁₈ are contained.
In addition, from Test Examples (7) to (11), the solidified material for coal ash containing a calcined product of Ca (OH) ₂ or a mixture of CaCO ₃ and Al (OH) ₃ is a positive material containing heavy metals and other substances. It can be understood that it has the property of adsorbing and insolubilizing ions and anions. Further, such characteristics are better when the molar ratio of Ca to Al (Ca / Al) is in the range of 2 to 5 in the fired product of the mixture, and the firing temperature of the fired product is 600 ° C. or higher. If so, it can be understood that it is superior.

From Test Examples (12) to (14), a solidified product produced by blending a solidified material for coal ash containing a fired product of a mixture of CaCO ₃ and Al (OH) ₃ with coal ash and water is compressed. It can be understood that it is strong and strong. The compression strength of the solidified product is higher when the molar ratio of Ca to Al (Ca / Al) is in the range of 1 to 10 in the fired product of the mixture, and the firing temperature of the fired product is 800 to 1200. It can be understood that the temperature is higher at ° C.
Furthermore, the solidified material blended with the coal ash solidifying material has higher compressive strength than the solidified material blended with alumina cement or Portland cement. The solidified product prepared by adjusting the mass of the calcined product contained in the material to be 30 to 60% by mass with respect to the total mass of the calcined product and coal ash is a solidified mixture of alumina cement or Portland cement. It can be understood that the compressive strength is much higher than that of the product.

From Test Examples (15) and (16), the solidified product containing the solidified material for coal ash containing the fired product of the mixture of CaCO ₃ and Al (OH) ₃ includes Ca (OH) ₂ and Ca ₃ Al _2. (SiO ₄ ) (OH) _{8 and} other solidified compounds containing alumina cement and Portland cement are included, and the coal ash solidified material is made of sand instead of coal ash. It can be understood that when blended, a solidified product having a high compressive strength cannot be produced, such as having properties different from those of alumina cement and Portland cement.

From the test example (17), according to the solidified material for coal ash containing a fired product of a mixture of CaCO ₃ and Al (OH) ₃ , a solidified product with high compressive strength is produced regardless of the type of coal ash used. I understand what I can do.
Further, according to the test example (18), according to the solidified material for coal ash containing the calcined product of the mixture of CaCO ₃ and Al (OH) ₃ , when producing the solidified product, It can be understood that a solidified product with higher compressive strength can be produced in a short period of time by solidifying by steam curing at a temperature of 60 ° C. or higher.

From Test Examples (19) and (20), the solidified material blended with the solidified material for coal ash containing the calcined product of the mixture of CaCO ₃ and Al (OH) ₃ adheres to the coal ash and is mixed into the solidified material. It can be understood that it is effective in suppressing elution of ions such as heavy metals, and in particular, even when the concentration of ions such as heavy metals adhering to coal ash is very high, it exhibits a sufficient elution suppression effect.
Moreover, it can be understood that the elution suppression effect of ions such as heavy metals of the solidified material blended with the solidified material for coal ash is much higher than the solidified material blended with alumina cement or Portland cement.

From the test example (21), the solidified material for coal ash containing the calcined product of the mixture of Ca (OH) ₂ and Al (OH) ₃ is the calcined product of the mixture of CaCO ₃ and Al (OH) _3. It can be understood that a solidified product having a high compressive strength can be produced by blending coal ash and water, kneading and solidifying in the same manner as the coal ash solidifying material included.

The present invention provides a solidified material for coal ash that can be mixed with coal ash and water, etc., molded into an arbitrary shape and solidified firmly, and can suppress elution of cations and anions containing heavy metals and the like. Especially usefulness is recognized, and usefulness is recognized in providing the method of manufacturing the solidified material which can be utilized for a wide range of uses, such as a construction and civil engineering material.

Claims (8)

A solidified material for coal ash, comprising a fired product of a mixture of at least one of Ca (OH) ₂ and CaCO ₃ and Al (OH) ₃ .   2. The solidified material for coal ash according to claim 1, wherein the calcined product of the mixture has a Ca to Al molar ratio (Ca / Al) in the range of 1 to 10. 3.   2. The coal ash solidified material according to claim 1, wherein a molar ratio of Ca to Al (Ca / Al) is in a range of 2 to 5 in the fired product of the mixture.   The solidified material for coal ash according to any one of claims 1 to 3, wherein a firing temperature of the fired product is 600 ° C or higher.   The solidification material for coal ash according to any one of claims 1 to 3, wherein a firing temperature of the fired product is 800 to 1200 ° C.   A solidified material for coal ash according to any one of claims 1 to 5, coal ash, water, and, if necessary, other raw materials are blended and kneaded to form a paste, A method for producing a solidified product, characterized by forming into a predetermined shape and solidifying.   Compounding the solidified material for coal ash such that the mass of the fired product contained in the solidified material for coal ash is 30 to 60% by mass with respect to the total mass of the calcined product and the coal ash. The manufacturing method of the solidified material of Claim 6 characterized by these.   The method for producing a solidified product according to claim 6 or 7, wherein the paste-like material is solidified by steam curing at a temperature of 60 ° C or higher.