Method for treating incineration ash

Abstract

To provide a treatment method for suppressing elution of lead, hexavalent chromium, and fluorine from incineration ash.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)], and / or (b) at least one copolymer or a salt thereof selected from maleic acid-based copolymers having a weight average molecular weight of 3,000 or more and 100,000 or less 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 / or 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 a recycled material, such as a cement raw material, an antioxidant for steelmaking, or an admixture. However, 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 following components (A) to (C) to obtain a mixture: Patent Document 2 discloses a method for treating heavy metal-containing ash, which comprises adding a reducing agent and a heavy metal immobilizing agent to soot containing copper and lead and kneading the mixture, wherein the reducing agent is one or more compounds selected from the group consisting of hydrogen compounds, sulfur (III) compounds, iron powder, sugars, aliphatic carboxylic acids or derivatives thereof, aldehydes, silicon-based polymer compounds, hydrazine or derivatives thereof, tannin or derivatives thereof, morpholine or derivatives thereof, hindered phenols, gall or derivatives thereof, and rosins, and the heavy metal immobilizing agent is a nitrogen-sulfur chelating agent. Patent Document 3 discloses a soil solidification agent containing granulated slag and gypsum dihydrate as main ingredients, compounded with a main solidification agent consisting of an alkaline stimulant made of slaked lime or cement, and a solidification assistant consisting of five or more selected from potassium chloride, magnesium chloride, sodium chloride, calcium chloride, ammonium chloride, potassium carbonate, sodium sulfate, calcium phosphate, barium oxide, and manganese dioxide, and one or more selected from citric acid, tartaric acid, and maleic acid. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Japanese Patent Application Publication No. 2020-000968 [Patent Document 2] Japanese Patent Application Laid-Open No. 2006-095409 [Patent Document 3] Japanese Patent Application Laid-Open No. 2005-272510 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 / or (b) one or more copolymers or salts thereof selected from acrylic acid / maleic acid copolymers or salts thereof having a weight-average molecular weight of 3,000 or more and 100,000 or less [hereinafter referred to as compound (b)] The present inventors have discovered that a method for treating incineration ash by mixing water with lead, hexavalent chromium, fluorine, etc., can be effectively suppressed from leaching out with a simple and easy operation, and have thus 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 [referred to as compound (a)], and / or (b) one or more copolymers or salts thereof selected from maleic acid copolymers or salts thereof having a weight-average molecular weight of 3,000 or more and 100,000 or less [hereinafter referred to as compound (b)] and water. The present invention also relates to a method for treating incineration ash, which comprises mixing the above compound (a) and water with the incineration ash. The present invention also relates to a method for treating incineration ash, which comprises mixing the above compound (b) and water with the incineration ash. The present invention also relates to a granulated material for treating incineration ash, which contains the compound (a) and / or the compound (b) in incineration ash. The present invention also relates to a method for producing granulated material for treating incineration ash, which comprises adding dropwise an aqueous solution containing the compound (a) and / or the compound (b) to incineration ash or a mixture containing incineration ash. The present invention also relates to a method for treating incineration ash, which includes a step of producing the granulated material. Furthermore, the present invention provides (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)], (e) one or more compounds selected from glycerin, propylene glycol, and diethylene glycol [hereinafter referred to as compound (e)], and water. [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 a salt thereof and hydroxymethanesulfinic acid or a salt thereof, 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, one or more copolymers selected from maleic acid copolymers or salts thereof as compound (b) 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 maleic acid copolymer of compound (b) is a copolymer of maleic acid, maleic anhydride, and a monomer copolymerizable therewith, and maleic acid may be a salt. Furthermore, examples of monomers copolymerizable with maleic acid and maleic anhydride include unsaturated monocarboxylic acids, unsaturated dicarboxylic acids, and their salts or anhydrides. Specific examples of unsaturated monocarboxylic acids include acrylic acid, methacrylic acid, dimethylacrylic acid, vinylacetic acid, allylacetic acid, propylideneacetic acid, ethylidenepropionic acid, and their salts or anhydrides. Furthermore, examples of unsaturated dicarboxylic acids include fumaric acid, citraconic acid, itaconic acid, methylenemalonic acid, mesaconic acid, and their salts or anhydrides. Furthermore, examples of monomers copolymerizable with maleic acid and maleic anhydride include polyethylene oxide monoallyl ether, polypropylene oxide monoallyl ether, and methoxypolyethylene oxide monoallyl ether.

[0017] The maleic acid copolymer or its salt as compound (b) is preferably an acrylic acid / maleic acid copolymer, and examples thereof include sodium salt of acrylic acid / maleic acid copolymer, potassium salt of acrylic acid / maleic acid copolymer, and ammonium salt of acrylic acid / maleic acid copolymer, with sodium salt of acrylic acid / maleic acid copolymer being preferred. These copolymers may be any of alternating polymers, block polymers, and random polymers.

[0018] The molar ratio of acrylic acid units to maleic acid units in the acrylic acid / maleic acid copolymer, expressed as (number of moles of acrylic acid units) / (number of moles of maleic acid units), is preferably 1 / 99 or more, more preferably 10 / 90 or more, even more preferably 40 / 60 or more, and is preferably 99 / 1 or less, more preferably 90 / 10 or less, even more preferably 80 / 20 or less.

[0019] From the viewpoint of suppressing fluorine elution, the weight average molecular weight of compound (b) is 3,000 or more, preferably 5,000 or more, more preferably 10,000 or more, and 100,000 or less, preferably 80,000 or less, more preferably 60,000 or less.

[0020] 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 / or (b) one or more copolymers or salts thereof selected from acrylic acid / maleic acid copolymers having a weight-average molecular weight of 3,000 or more and 100,000 or less; and water.

[0021] 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, from the viewpoint of suppressing elution of hexavalent chromium, 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 economy.

[0022] 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 0.2% 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.

[0023] 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.

[0024] In the present invention, the incineration ash, compound (a) and / or 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) and / or compound (b), and water may be supplied to the kneader separately or in a premixed state. Also, compound (a) and / or compound (b) may be dissolved in water and supplied as an aqueous solution.

[0025] 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.

[0026] The composition for treating incineration ash obtained as described above can be cured in air at an ambient temperature of about 0 to 35°C for 1 to 48 hours to efficiently suppress the elution of harmful substances such as lead, fluorine, and hexavalent chromium.

[0027] The treatment method of the present invention may be carried out using granulated material for incineration ash treatment containing compound (a) and / or compound (b). That is, the treatment method of the present invention preferably comprises a step of kneading the incineration ash, compound (a) and / or compound (b), and water to obtain granulated material for incineration ash treatment. The granulated material has the same particle size, density, strength, etc. as natural sand or gravel, and therefore can be recycled and effectively utilized while protecting natural resources. Examples of uses for the granulated material for incineration ash treatment according to the treatment method of the present invention include banking materials, backfill materials, and roadbed materials.

[0028] 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).

[0029] When using granulated material for incineration ash treatment, hydraulic powder and / or aluminum sulfate may be mixed in order to improve the strength of the granulated material and to facilitate granulation.

[0030] 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.

[0031] 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). For example, blast furnace slag cement, fly ash cement, and silica fume cement 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.

[0032] The amount of hydraulic powder mixed with 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 improving the strength of the granulated product for incineration ash treatment, 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 ease of production of the granulated product.

[0033] 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.

[0034] From the viewpoint of assisting in the suppression of fluorine elution, improving the strength of the granulated product, and assisting in the suppression of hexavalent chromium elution, one or more compounds selected from sodium thiosulfate, sodium dithionite, and sodium pyrosulfite [hereinafter referred to as compound (d)] may be mixed and used. Of these, sodium thiosulfate is preferred. The amount of compound (d) mixed with the incineration ash is preferably 0.01% by mass or more, more preferably 0.05% by mass or more, and even more preferably 0.1% by mass or more, from the viewpoint of assisting in suppressing fluorine elution, and is preferably 5.0% by mass or less, more preferably 2.0% by mass or less, and even more preferably 1.0% by mass or less, from the viewpoint of economy.

[0035] In addition, in a treatment method using granulated material for incineration ash treatment, 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 for incineration ash treatment. 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 by 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.

[0036] 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 / or 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.

[0037] 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 / or compound (b) dropwise or spraying it onto the incineration ash in step 2.

[0038] The dropping or spraying of the aqueous solution of compound (a) and / or compound (b) in step 2 is preferably carried out with sufficient stirring, since this allows granulation to proceed efficiently and results in granules with a small amount of fine particles. The same applies to the dropping of the aqueous solution of aluminum sulfate in step 3.

[0039] 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 / or compound (b) and aluminum sulfate are dissolved may be added.

[0040] After completion of step 2 and / or step 3, further stirring may be carried out 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.

[0041] The granulated material for incineration ash treatment obtained as described above can be cured in air at an ambient temperature of about 0 to 35°C for 1 to 14 days to efficiently suppress the leaching of harmful substances such as lead, fluorine, and hexavalent chromium.

[0042] The granulated material for incineration ash treatment of the present invention may contain, as compound (d), one or more compounds selected from sodium thiosulfate, sodium dithionite, and sodium pyrosulfite. From the viewpoint of suppressing fluorine elution, sodium thiosulfate is preferred. Furthermore, from the viewpoint of solubility, compound (d) is preferably a compound having water of crystallization. The content of compound (d) in the granulated product for incineration ash treatment of the present invention is preferably 1% by mass or more, more preferably 2% by mass or more, and even more preferably 5% by mass or more, from the viewpoint of suppressing fluorine elution, and is preferably 30% by mass or less, preferably 25% by mass or less, and even more preferably 20% by mass or less, from the viewpoint of uniform solubility.

[0043] From the viewpoint of good production efficiency, it is preferable to add compound (d) in step 2 of the above-mentioned method for producing granules for use in incineration ash treatment in the same manner as compound (a) and / or compound (b).

[0044] [Additive for incineration ash treatment] The additive for incineration ash treatment of the present invention contains compound (a) and / or compound (b), one or more compounds selected from glycerin, propylene glycol, and diethylene glycol [hereinafter referred to as compound (e)], and water. By using the additive for incineration ash treatment containing compound (e), it is possible to produce a composition for incineration ash treatment and a granulated material for incineration ash treatment, and to treat incineration ash using these, without the adverse effects of freezing, even in cold seasons or cold regions where the outside air temperature is below freezing.

[0045] From the viewpoint of solubility, compound (a) of the incineration ash treatment additive of the present invention is preferably a compound having water of crystallization. Moreover, from the viewpoint of anti-freezing, the content of compound (a) in the incineration ash treatment additive is preferably 10% by mass or more, more preferably 15% by mass or more, even more preferably 20% by mass or more, and from the viewpoint of uniform solubility, it is preferably 45% by mass or less, preferably 40% by mass or less, even more preferably 35% by mass or less.

[0046] The content of compound (b) in the additive for incineration ash treatment of the present invention is preferably 1% by mass or more, more preferably 2% by mass or more, and even more preferably 5% by mass or more from the viewpoint of anti-freezing, and is 25% by mass or less, more preferably 20% by mass or less, and even more preferably 15% by mass or less from the viewpoint of uniform solubility and solution viscosity.

[0047] The content of compound (e) in the additive for incineration ash treatment of the present invention is preferably 1% by mass or more, more preferably 2% by mass or more, and even more preferably 5% by mass or more from the viewpoint of anti-freezing, and is 20% by mass or less, more preferably 15% by mass or less, and even more preferably 10% by mass or less from the viewpoint of economy and preventing a decrease in strength of the granulated product.

[0048] The additive for treating incineration ash of the present invention contains one or more compounds selected from sodium thiosulfate, sodium dithionite, and sodium pyrosulfite as compound (d), thereby increasing the solubility of compound (e). From the viewpoint of the solubility of compound (d) itself, compound (d) is preferably a compound having water of crystallization. The content of compound (d) in the additive for incineration ash treatment of the present invention is preferably 1% by mass or more, more preferably 2% by mass or more, and even more preferably 5% by mass or more, from the same viewpoint as the granules for incineration ash treatment described above, and from the viewpoint of uniform solubility, it is preferably 30% by mass or less, preferably 25% by mass or less, and even more preferably 20% by mass or less.

[0049] The additive for incineration ash treatment of the present invention contains water. That is, the additive for incineration ash treatment of the present invention is a liquid, preferably an aqueous solution. From the viewpoint of solubility, the water content in the additive for incineration ash treatment of the present invention is preferably 40% by mass or more, more preferably 42% by mass or more, and even more preferably 45% by mass or more, and from the viewpoint of anti-freezing, it is preferably 65% ​​by mass or less, more preferably 62% by mass or less, and even more preferably 58% by mass or less. The content of water in the additive for treating incineration ash of the present invention includes the water of crystallization of compound (a) and the water of crystallization of compound (d).

[0050] The pH of the additive for treating incineration ash of the present invention at 25°C is preferably 6 or more, more preferably 7 or more, and preferably 11 or less, more preferably 10 or less, from the viewpoint of storage stability. [Example]

[0051] 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. at 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) Sodium salt of acrylic acid / maleic acid (71 / 29) copolymer (weight average molecular weight 32,000, manufactured by Kao Corporation) (b-2) Sodium salt of acrylic acid / maleic acid (44 / 56) copolymer (weight average molecular weight 21,500, manufactured by Kao Corporation) Compound (c): (c-1) Sodium salt of acrylic acid polymer (weight average molecular weight 30,000, manufactured by Kao Corporation) (c-2) Triethanolamine (Fujifilm Wako Pure Chemical Industries, Ltd.) (c-3) Sorbitol (Cargill "SORBIDEX 71100") (c-4) Citric acid (Fujifilm Wako Pure Chemical Industries, Ltd.) (c-5) Acetaldehyde (Fujifilm Wako Pure Chemical Industries, Ltd.) Compound (d): (d-1) Sodium thiosulfate pentahydrate (Fujifilm Wako Pure Chemical Industries, Ltd.) Compound (e): (e-1) Glycerin (Apical "APICID G995U USP") (e-2) Diethylene glycol (Fujifilm Wako Pure Chemical Industries, Ltd.) (e-3) Propylene glycol (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)

[0052] <Preparation of composition for treating incineration ash> 3.0 g of distilled water containing compound (a) and / or compound (b) dissolved therein was slowly added dropwise to 30 g of paper sludge 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 composition was crushed in a mortar to prepare a sample.

[0053] <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.

[0054] <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 compound (a) and / or compound (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 aged in air (20°C) for 7 days.

[0055] <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.

[0056] 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.

[0057] <Method for measuring eluted fluorine> The test solution was analyzed by ion chromatography (Thermo Scientific Corporation, DIONEX 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.

[0058] <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.

[0059] A lead elution test was conducted on paper sludge incineration ash using a composition for treating incineration ash prepared by adding water and compound (a) or compound (b) in the amounts (mass%) shown in Table 1. The results are shown in Table 1.

[0060] [Table 1]

[0061] By using (a-1) sodium hydroxymethanesulfonate or (a-2) sodium hydroxymethanesulfinate as compound (a), or by using (b-1) sodium salt of acrylic acid / maleic acid (71 / 29) copolymer or (b-2) sodium salt of acrylic acid / maleic acid (44 / 56) copolymer as compound (b), the amount of lead elution could be suppressed to 0.006 mg / L or less. On the other hand, when compound (a) and compound (b) were not added but (c-2) triethanolamine was added, lead elution of 0.03 mg / L or more was observed.

[0062] A hexavalent chromium elution test was carried out on paper sludge incineration ash using a composition for treating incineration ash prepared by adding compound (a) and water in the amounts (mass %) shown in Table 2. The results are shown in Table 2.

[0063] [Table 2]

[0064] When (a-1) sodium hydroxymethanesulfonate or (a-2) sodium hydroxymethanesulfinate was used as compound (a), the amount of hexavalent chromium eluted was less than the detection limit of 0.02 mg / L. On the other hand, when neither compound (a) nor (b) was added (Comparative Example 3) or when (c-2) triethanolamine, (c-3) sorbitol, (c-4) citric acid, and (c-5) acetaldehyde were added (Comparative Examples 4-8), elution of lead at a level of 2.8 mg / L or more was observed.

[0065] Granules for incineration ash treatment were produced by adding compound (a), compound (b) or (c), water, hydraulic powder, and aluminum sulfate in the amounts (mass%) shown in Table 3 to paper sludge incineration ash, and then tests were conducted to determine the elution of fluorine, hexavalent chromium, and lead. The results are shown in Table 3.

[0066] [Table 3]

[0067] As is clear from Table 3, the amount of fluorine elution was suppressed to 0.5 mg / L or less in Examples 10 to 18. On the other hand, even when neither compound (a) nor compound (b) was added (Comparative Examples 9 and 10) or when (c-1) acrylic acid polymer or (c-2) triethanolamine was added (Examples 19 and 20), the amount of fluorine elution was 0.9 mg / L or less. In Examples 10-18, 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 16, where 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, which was smaller than that of Comparative Examples 9-11. In addition, in Examples 19 and 20, where only compound (a) was used, inhibition of elution of fluorine, hexavalent chromium, and lead was observed.

[0068] Compound (a), compound (b), compound (d), water, hydraulic powder, and aluminum sulfate were added to paper sludge incineration ash in the amounts (mass%) shown in Table 4 to produce granules for incineration ash treatment, and a fluorine elution test was conducted. The results are shown in Table 4.

[0069] [Table 4]

[0070] In Examples 21 to 23, the reduction in the amount of fluorine elution was 0.3 mg / L or less, demonstrating the effect of adding compound (d-1). On the other hand, the addition of compound (d-1) alone was not effective in suppressing fluorine elution (Comparative Example 12). The granules for incineration ash treatment of Examples 22 and 23 correspond to those obtained by adding compound (d-1) to the granules of Examples 11 and 12 in Table 3. Compared to Examples 11 and 12, fluorine elution is more suppressed in Examples 22 and 23. Furthermore, the amounts of eluted hexavalent chromium and lead in Examples 22 and 23 were below the detection limits of 0.02 mg / L and 0.001 mg / L, respectively, similar to the results of Examples 11 and 12. This demonstrates that adding compound (d-1) to the granules does not interfere with the suppression of elution of hexavalent chromium and lead.

[0071] <Preparation of additives for incineration ash treatment> In a 50 mL screw tube, predetermined amounts of compound (a), compound (d), and water were mixed so that the total amount of the additive for incineration ash was 50 g. After confirming complete dissolution, compound (b) and compound (e) were added and mixed until uniform.

[0072] The storage stability was evaluated, and the results are shown in Table 5. <Storage stability of additives for incineration ash treatment> The additive for incineration ash was adjusted to a total amount of 50 g, stored in a freezer at -10°C for 7 days, and the appearance was checked.

[0073] [Table 5]

[0074] As is clear from Examples 24-34 in Table 5, the additive for incineration ash treatment containing compound (e) maintained a uniformly dissolved state even after storage at -10°C for 7 days. On the other hand, in Comparative Examples 13-17, which did not contain compound (e), the additive froze after storage at -10°C for 7 days. Furthermore, in Comparative Example 18, in which the total water content was 35% by mass, the additive for incineration ash treatment was insoluble even before freezing, and compound (e) did not function effectively.

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 / or (b) one or more copolymers or salts thereof selected from maleic acid copolymers or salts thereof having a weight-average molecular weight of 3,000 or more and 100,000 or less [hereinafter referred to as compound (b)], A method for treating incineration ash by mixing it with water.

2. 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; A method for treating incineration ash by mixing it with water.

3. A method for treating incineration ash, comprising: (b) one or more copolymers or salts thereof selected from maleic acid copolymers or salts thereof having a weight average molecular weight of 3,000 or more and 100,000 or less; A method for treating incineration ash by mixing it with water.

4. The method for treating incineration ash according to any one of claims 1 to 3, wherein the incineration ash is paper sludge incineration ash.

5. The method for treating incineration ash according to any one of claims 1 to 3, further comprising mixing hydraulic powder.

6. The method for treating incineration ash according to any one of claims 1 to 3, further comprising mixing aluminum sulfate.

7. The method for treating incineration ash according to any one of claims 1 to 3, further comprising mixing one or more compounds selected from sodium thiosulfate, sodium dithionite, and sodium pyrosulfite [hereinafter referred to as compound (d)].

8. 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 / or (b) one or more copolymers or salts thereof selected from maleic acid copolymers or salts thereof having a weight-average molecular weight of 3,000 or more and 100,000 or less [hereinafter referred to as compound (b)] Granulated material for incineration ash treatment containing

9. 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)] Granulated material for incineration ash treatment containing

10. Incineration ash or a mixture containing incineration ash, (b) one or more copolymers or salts thereof selected from maleic acid copolymers or salts thereof having a weight-average molecular weight of 3,000 or more and 100,000 or less [hereinafter referred to as compound (b)] Granulated material for incineration ash treatment containing

11. The granulated material for incineration ash processing according to any one of claims 8 to 10, wherein the incineration ash is paper sludge incineration ash.

12. The granulated material for treating incineration ash according to any one of claims 8 to 10, wherein the mixture containing incineration ash is a mixture containing hydraulic powder and / or aluminum sulfate.

13. The mixture containing incineration ash is a mixture containing one or more compounds selected from sodium thiosulfate, sodium dithionite, and sodium pyrosulfite [hereinafter referred to as compound (d)]. Granulated material for incineration ash processing according to any one of claims 8 to 10.

14. 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 / or (b) one or more copolymers or salts thereof selected from maleic acid copolymers or salts thereof having a weight average molecular weight of 3,000 or more and 100,000 or less; A method for producing granulated material for incineration ash treatment, comprising a step of dropping or spraying an aqueous solution containing the above.

15. A method for treating incineration ash, comprising the steps of claim 14.

16. (a) one or more compounds selected from hydroxymethanesulfonic acid or a salt thereof and hydroxymethanesulfinic acid or a salt thereof; one or more compounds selected from glycerin, propylene glycol, and diethylene glycol [hereinafter referred to as compound (e)], and water.

17. The additive for treating incineration ash according to claim 16, further comprising one or more compounds selected from sodium thiosulfate, sodium dithionite, and sodium pyrosulfite [hereinafter referred to as compound (d)].

18. The additive for treating incineration ash according to claim 16, wherein the content of the compound (e) is 1% by mass or more and 20% by mass or less.

19. The additive for treating incineration ash according to claim 16, wherein the content of water including water of crystallization is 40% by mass or more and 65% by mass or less.

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