Method for treating incineration ash

Abstract

To provide a method for treating incineration ash containing harmful substances such as lead, fluorine, and hexavalent chromium.SOLUTION: Incineration ash is mixed with (a) at least one compound selected from hydroxymethanesulfonic acid or a salt thereof and hydroxymethanesulfinic acid or a salt thereof [Compound (a)], (b) at least one compound selected from monoalkanolamine or a salt thereof and dialkanolamine or a salt thereof [Compound (b)], and water, thereby treating the incineration ash. A granulated material for incineration ash treatment containing incineration ash and Compound (a) and Compound (b) is produced to treat the incineration ash.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to a method for treating incineration ash containing harmful substances such as lead, fluorine, and hexavalent chromium, and to a granulated product in which the elution of such harmful substances is suppressed and which can be suitably reused as civil engineering and construction materials such as roadbed materials and ground materials. [Background technology]

[0002] In recent years, there has been a strong demand for the reduction of industrial waste from the perspective of environmental conservation. This reduction of industrial waste is a requirement for all companies and local governments that generate electricity or incinerate waste, and the paper and pulp industry is no exception.

[0003] In this context, the handling of incineration ash has become a major social issue. Currently, some incineration ash is effectively utilized as recycled materials, such as cement raw materials, antioxidants for steelmaking, and admixtures, while the remainder is often landfilled as industrial waste. One reason for the limited reuse is that incineration ash often exceeds the leaching levels of hazardous components listed in the soil environmental standards (Ministry of the Environment Notification No. 18, revised Ministry of the Environment Notification No. 48) established pursuant to Article 5, Paragraph 3, Item 4 of the Enforcement Regulations of the Soil Contamination Countermeasures Act (Ministry of the Environment Order No. 29 of 2002). Among these hazardous components, organic hazardous components are decomposed during incineration and therefore hardly remain in the incineration ash, posing no problem. However, leaching levels of inorganic hazardous components, such as lead, fluorine, and hexavalent chromium, often exceed the standards. When the leaching levels of hazardous components exceed the soil environmental standards, the ash cannot be applied to soil, posing a major obstacle to reuse.

[0004] In most cases, incineration ash is a fine solid powder, requiring careful handling as dust. It is common to add moisture to incineration ash to prevent dust dispersion during discharge or transportation. However, if incineration ash with added moisture is left in the atmosphere, the added moisture reacts with the calcium in the ash to form calcium hydroxide, which then reacts with carbon dioxide in the atmosphere to form calcium carbonate. As a result, the leaching pH of the incineration ash decreases, increasing the amount of hexavalent chromium leached. Furthermore, adding a large amount of moisture reduces the absorbency of the incineration ash, which can lead to problems when reused as absorbent products that take advantage of the ash's excellent absorbency.

[0005] In order to satisfy the soil environmental standards stipulated in the Soil Contamination Countermeasures Act, many technologies have been investigated and patent applications have been filed for the addition of some kind of insolubilizing agent to contaminated materials to reduce the amount of inorganic harmful components leached out. Patent Document 1 describes the following in incineration ash containing fluorine: (A) Component: Water Component (B): acid or acid source (however, the acid source for component (B) does not include alkanolamine salts.) Component (C): Alkanolamine or its salt A method for treating incineration ash is disclosed, which comprises a step of mixing the above components to obtain a mixture. Patent Document 2 discloses a method for solidifying alkaline fly ash containing harmful substances, which is discharged from incinerators for municipal waste, sewage sludge, etc., with a hydraulic material, characterized in that the fly ash is treated with a mineral acid or its acid salt, and then solidified using a hydraulic material and a solidification aid in combination, and the solidification aid contains a metal salt of a higher fatty acid and an organic amino compound such as ethanolamine. Patent Document 3 discloses a method for treating a hexavalent chromium-containing substance, which is characterized by bringing a material to be treated containing hexavalent chromium into contact with a compound having a coordinate bond to reduce the hexavalent chromium, and uses a reducing compound containing nitrogen, such as triethanolamine or o-phenanthroline, as the compound having a coordinate bond. Patent Document 4 discloses a method for treating harmful substances contained in fly ash discharged from an incinerator, which comprises adding a phosphate-based heavy metal immobilizing agent and a dioxin decomposing agent such as an amine compound, for example, an alkanolamine such as monoethanolamine, diethanolamine, triethanolamine, methanolamine, or aminomethylpropanol; a lower alkyl-substituted amine such as diethylamine, propylamine, or ethylenediamine; or a cyclic amine such as aniline, to the fly ash, kneading the mixture, and returning the resulting kneaded mixture to the incinerator. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Japanese Patent Application Publication No. 2020-000968 [Patent Document 2] Japanese Patent Application Publication No. 10-113634 [Patent Document 3] Japanese Patent Application Laid-Open No. 2004-121949 [Patent Document 4] Japanese Patent Application Laid-Open No. 2003-340394 Summary of the Invention [Problem to be solved by the invention]

[0007] An object of the present invention is to provide a treatment method for suppressing the elution of lead, hexavalent chromium, and fluorine from incineration ash. [Means for solving the problem]

[0008] As a result of intensive research by the present inventors, it was found that the incineration ash (a) one or more compounds selected from hydroxymethanesulfonic acid or a salt thereof and hydroxymethanesulfinic acid or a salt thereof [hereinafter referred to as compound (a)], and (b) one or more compounds selected from monoalkanolamines or salts thereof and dialkanolamines or salts thereof [hereinafter referred to as compound (b)] The inventors have found that by using a method for treating incineration ash in which the incineration ash is mixed with water, the elution of lead, hexavalent chromium, fluorine, etc. can be effectively suppressed with a simple and easy operation, and have arrived at the present invention. That is, the present invention provides: A method for treating incineration ash, comprising: (a) one or more compounds selected from hydroxymethanesulfonic acid or a salt thereof and hydroxymethanesulfinic acid or a salt thereof [hereinafter referred to as compound (a)], and (b) one or more compounds selected from monoalkanolamines or salts thereof and dialkanolamines or salts thereof [hereinafter referred to as compound (b)] and water. The present invention also relates to a granulated material for treating incineration ash, which contains the above compound (a) and the above compound (b) in incineration ash or a mixture containing incineration ash. The present invention also relates to a method for producing granulated material for treating incineration ash, which comprises a step of adding dropwise or spraying an aqueous solution containing the compound (a) and the compound (b) to incineration ash or a mixture containing incineration ash. The present invention further relates to a composition for treating incineration ash, which comprises incineration ash, the compound (a) and the compound (b). [Effects of the Invention]

[0009] The present invention can provide a treatment method for suppressing the elution of lead, hexavalent chromium, and fluorine from incineration ash. DETAILED DESCRIPTION OF THE INVENTION

[0010] First, the incineration ash used in the treatment method of the present invention will be described. In the treatment method of the present invention, general incineration ash can be used. This includes incineration ash or fly ash generated from municipal waste incineration plants and industrial waste incineration plants, and incineration ash from coal-fired power plants. In particular, it is preferable to use paper sludge incineration ash, which has a porous surface and can be used in a wide range of applications, such as as a deodorizer, water-retaining material, dehydration material, humidity conditioner, and compost promoter.

[0011] Paper sludge is waste generated from processes such as pulp manufacturing, paper manufacturing, and waste paper processing, and is commonly referred to as papermaking sludge. Paper sludge contains various raw materials commonly used in the papermaking field, including inorganic substances such as silica, calcium carbonate, talc, kaolin, and silica sand, which are used as pigments and fillers, organic substances such as pulp and papermaking chemicals, and ink components contained in waste paper. Paper sludge incineration ash is ash obtained by incinerating such paper sludge in a combustion device.

[0012] Paper sludge incineration ash may be obtained by mixing and burning paper sludge with other materials. Examples of other materials include waste tires, refuse-derived fuel (RDF), recycled paper-based plastics (RPF), wood chips, sawdust, cotton, rayon, hemp, newspapers, magazines, irrigation mud, wastewater sludge, and other general combustible materials. Fossil fuels such as heavy oil and coal may be mixed and burned with paper sludge in amounts sufficient to support combustion. However, the amount of other materials or fossil fuels used in the mixture must not impair the properties of the paper sludge incineration ash.

[0013] Next, compound (a), which is one or more compounds selected from hydroxymethanesulfonic acid or its salt and hydroxymethanesulfinic acid or its salt, will be described. Compound (a) is effective in suppressing the elution of lead, hexavalent chromium, and fluorine, and is particularly effective in suppressing the elution of lead and hexavalent chromium.

[0014] Two or more types of compound (a) can be used. The salts of hydroxymethanesulfonic acid and hydroxymethanesulfinic acid are preferably alkali metal salts, more preferably sodium salts. Hydrates of hydroxymethanesulfonic acid and hydroxymethanesulfinic acid may also be used. When a hydrate is used, the amount of compound (a) used is calculated as the anhydride.

[0015] Next, the compound (b), which is one or more compounds selected from monoalkanolamines or their salts and dialkanolamines or their salts, will be described. Compound (b) is effective in suppressing the elution of lead, hexavalent chromium, and fluorine, and is particularly effective in suppressing the elution of lead and fluorine.

[0016] The monoalkanolamine of compound (b) is represented by general formula (1). N(R 1 -OH)R 2 R 3 (1) [In the formula, R 1 represents an alkylene group having 1 to 4 carbon atoms. 2 and R 3 each independently represents a hydrogen atom or an alkyl group having 1 to 4 carbon atoms. Specific examples include methanolamine, ethanolamine, propyl alcoholamine, butanolamine, etc. Methanolamine and ethanolamine are preferred from the viewpoint of suppressing fluorine elution. Examples of salts of monoalkanolamine include salts of inorganic acids such as hydrochlorides and sulfates, and salts of organic acids such as acetates. In terms of easy availability, salts of inorganic acids are preferred, and hydrochlorides are more preferred.

[0017] The dialkanolamine of compound (b) is represented by general formula (2). N(R 4 -OH)(R 5 -OH)R 6 (2) [In the formula, R 4 and R 5 R each independently represents an alkylene group having 1 to 4 carbon atoms. 6represents a hydrogen atom or an alkyl group having 1 to 4 carbon atoms.] Specific examples include dimethanolamine, diethanolamine, dipropyl alcoholamine, dibutanolamine, methyl dimethanolamine, methyl diethanolamine, methyl dipropyl alcoholamine, methyl dibutanolamine, ethyl dimethanolamine, ethyl diethanolamine, ethyl dipropyl alcoholamine, and ethyl dibutanolamine. From the viewpoint of suppressing fluorine elution, diethanolamine and methyl diethanolamine are preferred. Examples of salts of dialkanolamine include salts of inorganic acids such as hydrochlorides and sulfates, and salts of organic acids such as acetates. From the viewpoint of easy availability, salts of inorganic acids are preferred, and hydrochlorides are more preferred.

[0018] In addition, compound (a), which is an organic acid, and compound (b), which is an organic base, may form a salt when they coexist. When a salt is formed, compound (a) and compound (b), which are the raw materials, can be considered to exist individually.

[0019] Next, the treatment method of the present invention will be described. (a) one or more compounds selected from hydroxymethanesulfonic acid or a salt thereof and hydroxymethanesulfinic acid or a salt thereof, and (b) one or more compounds selected from monoalkanolamines or salts thereof and dialkanolamines or salts thereof and water.

[0020] The amount of compound (a) mixed with the incineration ash is preferably 0.005% by mass or more, more preferably 0.01% by mass or more, and is preferably 10% by mass or less, more preferably 5% by mass or less, and even more preferably 3% by mass or less, from the viewpoint of suppressing elution of hexavalent chromium.

[0021] The amount of compound (b) mixed with the incineration ash is preferably 0.05% by mass or more, more preferably 0.1% by mass or more, and even more preferably 0.25% by mass or more, from the viewpoint of suppressing fluorine elution, and is preferably 10% by mass or less, more preferably 5% by mass or less, and even more preferably 2% by mass or less, from the viewpoint of economy.

[0022] The amount of water mixed with the incineration ash is preferably 2% by mass or more, more preferably 5% by mass or more, and even more preferably 10% by mass or more, from the viewpoint of preventing dust scattering, and is preferably 50% by mass or less, more preferably 30% by mass or less, and even more preferably 20% by mass or less, from the viewpoint of reducing the amount of transportation.

[0023] In the present invention, the incineration ash, compound (a), compound (b), and water are kneaded to produce a composition for treating incineration ash. There are no limitations on the kneading method, but a kneading method using a conventional stirrer is preferred from the standpoint of convenience. The kneading time is affected by the mixing device (such as the rotation speed and size of the stirrer), so it is preferable to adjust it appropriately, but 1 to 30 minutes is preferred, and 5 to 10 minutes is more preferred. There are no particular limitations on the mixing device used for kneading, and the raw materials can be kneaded using a device equipped with a kneading roll or kneading blades, but a tumbling kneader is most suitable for efficient kneading. Examples of suitable kneaders include the ELBA mixer (Kurihara), the intensive mixer (Eirich), and the Pellegaia (Kitagawa Iron Works). In the present invention, the incineration ash, compound (a), compound (b), and water may be supplied to the kneader separately or in a premixed state. Also, compound (a) and compound (b) may be dissolved in water and supplied as an aqueous solution.

[0024] Paper sludge incineration ash can also be pretreated before kneading. Pretreatments include, for example, pulverization, crushing, disintegration, classification, re-burning, re-drying, magnetic separation, etc., and can be carried out using any appropriate device known to those skilled in the art. Of course, the ash can also be used for kneading as is. From the viewpoint of energy consumption and cost, it is preferable not to carry out these pretreatments.

[0025] The composition for treating incineration ash obtained as described above can efficiently suppress the elution of harmful substances such as lead, fluorine, and hexavalent chromium by curing in air for 1 to 48 hours at an ambient temperature of about 0 to 35° C. Depending on the work process after treating the incineration ash, the composition may be cured for 48 hours or longer, and the elution suppression effect will be maintained.

[0026] The treatment method of the present invention may be carried out using granulated material for treating incineration ash containing compound (a) and compound (b). That is, the treatment method of the present invention preferably comprises a step of kneading the incineration ash, compound (a), compound (b), and water to obtain granulated material for treating incineration ash. The granulated material has the same particle size, density, strength, etc. as natural sand or gravel, and therefore can recycle and effectively utilize waste while protecting natural resources. Examples of uses for the granulated material for treating incineration ash according to the treatment method of the present invention include banking materials, backfill materials, and roadbed materials.

[0027] There is no limitation on the size of the granulated material for incineration ash treatment, and considering ease of handling, the average particle size is preferably 0.5 mm or more, more preferably 1.0 mm or more, and preferably 20 mm or less, more preferably 10 mm or less. The average particle size is a value calculated from the sieve passing rate in accordance with JIS A 1102-2014 (Sieving test method for aggregates).

[0028] When using granulated material for incineration ash treatment, a mixture containing hydraulic powder and / or aluminum sulfate may be used from the viewpoint of improving the strength of the granulated material and facilitating granulation.

[0029] The hydraulic powder is a powder that has the physical property of hardening through a hydration reaction, and examples thereof include cement and gypsum. Examples of cement include ordinary Portland cement, high-early-strength Portland cement, ultra-high-early-strength Portland cement, sulfate-resistant Portland cement, low-heat Portland cement, white Portland cement, and ecocement (e.g., JIS R5214, etc.). Among these, cement selected from ordinary Portland cement, sulfate-resistant Portland cement, and white Portland cement is preferred, with ordinary Portland cement being more preferred.

[0030] Furthermore, from the viewpoint of effective utilization of industrial waste, the hydraulic powder such as cement may contain powders having pozzolanic action and / or latent hydraulic properties, such as blast furnace slag, fly ash, and silica fume, as well as stone powder (calcium carbonate powder), etc. For example, blast furnace slag cement, fly ash cement, silica fume cement, etc. may be used. The hydraulic powder of the present invention is preferably ordinary Portland cement from the viewpoint of improving the strength of the granulated product, and more preferably ordinary Portland cement containing blast furnace slag from the viewpoint of assisting in suppressing the elution of hexavalent chromium.

[0031] The amount of hydraulic powder mixed with the incineration ash is preferably 0.1% by mass or more, more preferably 0.5% by mass or more, and even more preferably 1.0% by mass or more, from the viewpoint of ease of production of the granulated product, and is preferably 50% by mass or less, more preferably 30% by mass or less, and even more preferably 10% by mass or less, from the viewpoint of improving the strength of the granulated product.

[0032] The amount of aluminum sulfate mixed with the incineration ash is preferably 0.1% by mass or more, more preferably 0.2% by mass or more, and even more preferably 0.6% by mass or more from the viewpoint of assisting in suppressing fluorine elution, and is preferably 30% by mass or less, more preferably 10% by mass or less, and even more preferably 5% by mass or less from the viewpoint of suppressing hexavalent chromium elution. Aluminum sulfate may also be dissolved in water and used as an aqueous solution in the production of granules.

[0033] In addition, in the treatment method using granulated material, the amount of water mixed with the incineration ash is preferably 10% by mass or more, more preferably 15% by mass or more, and even more preferably 20% by mass or more, from the viewpoint of facilitating granulation, and is preferably 50% by mass or less, more preferably 45% by mass or less, and even more preferably 40% by mass or less, from the viewpoint of improving the strength of the granulated material. When producing granules, some of the mixed water may be lost due to consumption of water in the hydration reaction of incineration ash or hydraulic powder, evaporation due to heat generated during the hydration reaction, etc. Therefore, the amount of water in the produced granules for incineration ash treatment may be less than the amount of water mixed during production.

[0034] The production of granulated material for incineration ash treatment can be carried out using a known granulating device, but it is preferable to include the following steps 1 to 3 in order to ensure that granulation proceeds efficiently and that the particle size of the granulated material is uniform. Step 1: A step of kneading incineration ash and hydraulic powder to obtain a mixture containing incineration ash. Step 2: A step of adding dropwise or spraying an aqueous solution of compound (a) and compound (b) to the mixture obtained in step 1. Step 3: Following step 2, a step of dropping or spraying an aqueous solution of aluminum sulfate.

[0035] The kneading in step 1 can be carried out by the kneading method described above. That is, the kneading time is affected by the mixing equipment (such as the rotation speed and size of the stirrer), so it is preferable to adjust it appropriately, but 1 to 30 minutes is preferable, and 5 to 10 minutes is more preferable. There are no particular restrictions on the mixing equipment used for kneading, and the raw materials can be kneaded using an equipment equipped with kneading rolls or kneading blades, but for efficient kneading, a tumbling kneader is most suitable. Examples of suitable kneaders include the ELBA mixer (Kurihara), the intensive mixer (Eirich), and the Pellegaia (Kitagawa Iron Works). If no hydraulic powder is used, step 1 can be omitted, and the manufacturing process can begin by directly applying the aqueous solution of compound (a) and compound (b) dropwise or spraying it onto the incineration ash in step 2.

[0036] In step 2, the aqueous solution of compound (a) and compound (b) is preferably added dropwise or sprayed while stirring thoroughly, since this allows granulation to proceed efficiently and results in granules with little fine particles. The same applies to the addition of the aqueous solution of aluminum sulfate in step 3.

[0037] The order of steps 2 and 3 may be reversed, or the aqueous solution used in step 2 and the aqueous solution used in step 3 may be added simultaneously. Alternatively, an aqueous solution in which both compound (a) and compound (b) and aluminum sulfate are dissolved may be added.

[0038] After completion of step 2 and / or step 3, further stirring may be performed, which may be performed by manual stirring or by using a known mixing and stirring device. Alternatively, the mixture may be mixed uniformly in a kneader and then molded in a granulator such as a disc pelletizer.

[0039] The granulated material for incineration ash treatment obtained as described above can efficiently suppress the elution of harmful substances such as lead, fluorine, and hexavalent chromium by curing it in air at an ambient temperature of about 0 to 35°C for 1 to 14 days. Depending on the work process after incineration ash treatment, it may be cured for 14 days or more, and the elution suppression effect will be maintained. [Example]

[0040] In the examples and comparative examples, evaluations were carried out by the following methods. The incineration ash and reagents used were as follows. Paper sludge incineration ash: Ash generated by burning paper sludge, waste tires, RPF, etc. in a paper mill, with small and medium-sized gravel and wood chips removed. Compound (a): (a-1) Sodium hydroxymethanesulfonate (Fujifilm Wako Pure Chemical Industries: Formaldehyde Sodium Disulfite) (a-2) Sodium hydroxymethanesulfinate (Fujifilm Wako Pure Chemical Industries: Rongalite) Compound (b): (b-1) Diethanolamine (Fujifilm Wako Pure Chemical Industries, Ltd.) (b-2) Monoethanolamine (Fujifilm Wako Pure Chemical Industries, Ltd.: 2-aminoethanol) (b-3) Diethanolamine hydrochloride (Tokyo Chemical Industry Co., Ltd.) (b-4) Monoethanolamine hydrochloride (Fujifilm Wako Pure Chemical Industries, Ltd.: 2-aminoethanol hydrochloride) (b-5) Methyldiethanolamine (Fujifilm Wako Pure Chemical Industries, Ltd.: 2,2'-methyliminodiethanol) Compound (c): (c-1) Triethanolamine (Fujifilm Wako Pure Chemical Industries, Ltd.) Hydraulic powder (Sumitomo Osaka Cement: ordinary Portland cement) Aluminum sulfate (Fujifilm Wako Pure Chemical Industries: Aluminum sulfate 14-18 hydrate)

[0041] <Preparation of composition for treating incineration ash> 3.0 g of distilled water containing compound (a) and compound (b) was slowly added dropwise to 30 g of incineration ash using a dropper, stirred with a glass rod for 1 minute, and cured in air (20°C) for 24 hours. After curing, the mixture was crushed in a mortar to prepare a sample.

[0042] <Dissolution test> 20 g of the prepared composition for incineration ash treatment and 200 g of distilled water were added to a 300 mL Erlenmeyer flask and stirred for 6 hours using a magnetic stirrer. After stirring, the mixture was left to stand for 30 minutes and then centrifuged at approximately 3,000 revolutions per minute for 10 minutes. The supernatant was filtered through a membrane filter with a pore size of 0.8 μm, and the filtrate was accurately measured and used as the test solution.

[0043] <Preparation of granules for incineration ash treatment> 30 g of paper sludge incineration ash and hydraulic powder were placed in a 1000 mL beaker and mixed. Distilled water containing compounds (a) and (b) dissolved therein was slowly added dropwise with a dropper while rotating the beaker, followed by the addition of an aqueous aluminum sulfate solution. Granules with an average particle size of 3 mm or more were obtained. After granulation, the mixture was left to cure in air (20°C) for 7 days.

[0044] <Elution test using granulated material for incineration ash treatment> After curing, the granulated material was crushed in a mortar to a size of under 2 mm to prepare a sample. 20 g of crushed granules and 200 g of distilled water were added to a 300 mL Erlenmeyer flask and stirred for 6 hours using a magnetic stirrer. After stirring, the mixture was left to stand for 30 minutes and then centrifuged at approximately 3,000 revolutions per minute for 10 minutes. The supernatant was filtered through a 0.8 μm membrane filter, and the filtrate was accurately measured and used as the test solution.

[0045] Using each of the above test solutions, the amount of eluted lead, fluorine, and hexavalent chromium was measured by the following method. <Method for measuring eluted lead> The test solution was analyzed by ICP mass spectrometry (inductively coupled plasma mass spectrometer: Agilent Technologies 7800CS) according to the method specified in 54.4 of JIS K 0102 (testing method for industrial wastewater), and the amount of eluted lead was quantified.

[0046] <Method for measuring eluted fluorine> The test solution was analyzed by ion chromatography (Thermo Scientific Co., Ltd., DEONEX INTERGRION HPIC) according to the method specified in Appendix 7 of Notification No. 59 of the Environment Agency in 1971 (JIS K 0102 34.3), and the amount of eluted fluorine was determined.

[0047] <Method for measuring eluted hexavalent chromium> The test solution was analyzed by diphenylcarbazide absorptiometry (spectrophotometer: Hitachi High-Tech Science U2900) in accordance with the method specified in 65.2.1 of JIS K 0102 (testing method for industrial wastewater), and the amount of eluted hexavalent chromium was quantified.

[0048] A lead elution test was conducted on paper sludge incineration ash using a composition for treating incineration ash prepared by adding compound (a), compound (b), and water in the amounts (mass%) shown in Table 1. The results are shown in Table 1.

[0049] [Table 1]

[0050] By using (a-1) sodium hydroxymethanesulfonate or (a-2) sodium hydroxymethanesulfinate as compound (a), and further using (b-1) diethanolamine or (b-2) monoethanolamine as compound (b), the amount of hexavalent chromium elution could be suppressed to the detection limit of 0.02 mg / L or less, and the amount of lead elution could be suppressed to 0.006 mg / L or less. On the other hand, in a composition that did not contain compounds (a) and (b) but added (c-1) triethanolamine, hexavalent chromium elution of 2.8 mg / L or more and lead elution of 0.03 mg / L or more were observed.

[0051] Granules were produced by adding compound (a), compound (b), hydraulic powder, and aluminum sulfate to paper sludge incineration ash in the amounts (mass%) shown in Table 2, and then tests were conducted to determine the elution of fluorine, hexavalent chromium, and lead. The results are shown in Table 2.

[0052] [Table 2]

[0053] As is clear from Table 2, the amount of fluorine elution was suppressed to 0.7 mg / L or less in Examples 6 to 18. On the other hand, when neither compound (a) nor (b) was added (Comparative Examples 3 and 4) or when triethanolamine, which is comparative substance (c-1), was added as compound (b) (Comparative Examples 5 and 6), the amount of fluorine elution was 1.1 mg / L or more. In Examples 6 to 14 and 16 to 18, the amounts of elution of both hexavalent chromium and lead were below the detection limits of 0.02 mg / L and 0.001 mg / L. In Example 15, in which the amount of compound (a) added was as small as 0.01 mass% relative to the incineration ash, the amount of elution of hexavalent chromium was 1.8 mg / L, a value smaller than those of Comparative Examples 3 to 5. In Comparative Example 6, in which compound (a) and comparative substance (c-1) were used, the amount of elution of hexavalent chromium was kept below the detection limit, but elution of lead was significant. In Comparative Example 5, in which compound (a) was not added and only triethanolamine, the comparative substance (c-1), was added, elution of both hexavalent chromium and lead was significant.

Claims

1. A method for treating incineration ash, comprising: (a) one or more compounds selected from hydroxymethanesulfonic acid or a salt thereof and hydroxymethanesulfinic acid or a salt thereof [hereinafter referred to as compound (a)], and (b) one or more compounds selected from monoalkanolamines or salts thereof and dialkanolamines or salts thereof [hereinafter referred to as compound (b)] A method for treating incineration ash by mixing it with water.

2. 2. The method for treating incineration ash according to claim 1, wherein the incineration ash is paper sludge incineration ash.

3. 3. The method for treating incineration ash according to claim 1, further comprising mixing hydraulic powder.

4. 3. The method for treating incineration ash according to claim 1, further comprising mixing aluminum sulfate.

5. 3. The method for treating incineration ash according to claim 1, wherein the monoalkanolamine is monoethanolamine.

6. 3. The method for treating incineration ash according to 1 or 2, wherein the dialkanolamine is diethanolamine or methyldiethanolamine.

7. Incineration ash or a mixture containing incineration ash, (a) one or more compounds selected from hydroxymethanesulfonic acid or a salt thereof and hydroxymethanesulfinic acid or a salt thereof [hereinafter referred to as compound (a)], and (b) one or more compounds selected from monoalkanolamines or salts thereof and dialkanolamines or salts thereof [hereinafter referred to as compound (b)] Granulated material for incineration ash treatment containing

8. The granules according to claim 7, wherein the incineration ash is paper sludge incineration ash.

9. The granulated material for treating incineration ash according to claim 7 or 8, wherein the mixture containing incineration ash is a mixture containing hydraulic powder and / or aluminum sulfate.

10. Incineration ash or a mixture containing incineration ash, (a) one or more compounds selected from hydroxymethanesulfonic acid or a salt thereof and hydroxymethanesulfinic acid or a salt thereof, and (b) one or more compounds selected from monoalkanolamines or salts thereof and dialkanolamines or salts thereof A method for producing granulated material for incineration ash treatment, comprising a step of dropping or spraying an aqueous solution containing the compound.

11. In the incineration ash, (a) one or more compounds selected from hydroxymethanesulfonic acid or a salt thereof and hydroxymethanesulfinic acid or a salt thereof [hereinafter referred to as compound (a)], and (b) one or more compounds selected from monoalkanolamines or salts thereof and dialkanolamines or salts thereof [hereinafter referred to as compound (b)] A composition for treating incineration ash comprising:

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