JP6077765B2 - Anti-elution agent for harmful substances and elution prevention method using the same - Google Patents

Description

  The present invention relates to an elution inhibitor capable of effectively preventing elution of harmful substances from waste in an acidic environment, and an elution prevention method using the same.

  In recent years, various efforts have been made regarding the effective use of waste, but the results are not sufficient. Hundreds of thousands of tons of sewage sludge incineration ash is generated annually, and some of it is used for backfill soil, roadbed materials, or admixtures for concrete products, but most of it is industrial waste. It is disposed of in the ground or on the sea as an object. Fly ash is about 10 million tons of incinerated ash generated during the combustion of coal at coal-fired power plants or coal boilers, and some of it is backfilled as cement raw materials or earthwork materials, roadbed materials, concrete -Although it is used for admixtures and other products, most of it is disposed of in the ground or on the sea as industrial waste. Similarly, paper sludge ash is incinerated ash generated by incineration and volume reduction of paper sludge discharged from paper mills, and it is generated in millions of tons per year. Yes, most are disposed of as waste. In the future, it will be necessary to maximize the effective use of these wastes as earthwork materials in order to respond to the social situation such as the tightness of waste disposal sites and the reduction of environmental impact. However, these wastes have environmental safety issues such as the elution of heavy metals and harmful substances. Specifically, the amount of elution of fluorine, boron, arsenic, and selenium is mainly determined by soil environmental standards (announced by the Environment Agency). No. 46) is a problem for effective use as earthwork material. Table 1 shows the elution amounts of fluorine, boron, arsenic, and selenium specified in the soil environmental standards (Environment Agency Notification No. 46).

  Conventionally, fluorine insolubilization techniques include the use of calcium salts such as slaked lime to produce sparingly soluble calcium fluoride, and the process in which aluminum hydroxide is produced using aluminum salts such as aluminum sulfate. There are known methods for adsorption and insolubilization, methods for adsorption and insolubilization of fluorine in the process of producing magnesium hydroxide using a magnesium salt such as magnesium sulfate. Further, as a boron insolubilization technique, a method is known in which boron is adsorbed and insolubilized by using an aluminum salt such as aluminum sulfate or using aluminum sulfate and slaked lime in combination. As arsenic insolubilization technology, arsenic is adsorbed and insolubilized in the process of producing aluminum hydroxide using aluminum salt such as aluminum sulfate, and iron salt such as ferric chloride is used for hydroxylation. A method of adsorbing and insolubilizing arsenic in the process of iron generation is known. As a selenium insolubilization technique, an adsorption / insolubilization method using an iron salt or the like is known.

  However, since these insolubilization techniques have a low insolubilizing effect, it has been difficult to suppress the amount of the harmful substances eluted from the waste below the soil environment standard. Under such circumstances, methods for suppressing the elution of harmful substances in industrial waste have been proposed. That is, arsenic and hexavalent chromium are captured and insolubilized with a chelating agent such as dithiocarbamate or dithiocarbamic acid derivative (Patent Documents 1 and 2), thiosulfate compound is added to contaminated soil and incinerated ash, and incinerated ash is heated By adding a cement or lime, which is a hydraulic binder, to the incineration ash, a technology related to a device that insolubilizes heavy metals such as arsenic and selenium contained in the incineration ash, etc. (Patent Document 3) Technology that suppresses the elution of fluorine and boron contained (Patent Document 4), Technology that suppresses elution of fluorine from industrial waste by adding powder such as calcium aluminate to industrial waste such as steelmaking slag (Patent Document 5), calcium oxides and / or calcium hydroxide in boron-containing combustion ash generated by burning coal, paper sludge, etc. , Calcium sulfate, alumina cement, a technique for suppressing the elution of boron from the combustion ash by adding water (Patent Document 6), insolubilization containing calcium aluminate and calcium silicate This is a method for insolubilizing fluorine and / or boron using an agent, in which fluorine and / or boron is insolubilized by mixing the solid material containing fluorine and / or boron, the insolubilizing agent and water and then curing for a required period of time. (Patent Document 7), by adding and mixing pollutants that contain aluminum sulfate, sodium thiosulfate and iron powder as essential components to contaminated soil and incinerated ash, heavy metals such as arsenic and selenium and Technology to suppress elution of boron and fluorine (Patent Document 8), adding and mixing a solidifying material such as Portland cement and water to sewage sludge incineration ash Then, after granulation by rolling granulation method or compression granulation method, the elution of heavy metals such as arsenic is physically performed by forming asphalt film on the surface of the granulated product using asphalt / water emulsion. Technology (Patent Document 9), leaching inhibitor of harmful elements containing iron powder, calcium oxide, and aluminum oxide as essential components, fluorine, boron, heavy metals such as arsenic and selenium from fly ash A technique (Patent Document 10) that suppresses elution of selenium has been reported.

In addition, in order to effectively use waste containing heavy metals and toxic substances as earthwork materials, it is necessary to keep the effect of preventing elution of heavy metals, etc., in insolubilized waste regardless of environmental conditions. .
Although it is different from waste, it has become clear from past survey results that pH is the most important factor for environmental conditions in which harmful substances such as heavy metals are eluted in insolubilized contaminated soil. Regarding the dissolution behavior of heavy metals, etc. in response to changes in pH, there is an evaluation test method that considers the case where soil contaminated with heavy metals, etc. is insolubilized and exposed to acid rain at pH 4.0 at an annual rainfall of 2,000 mm for 100 years. Proposed by the Japan Soil Environment Center (GEPC Technical Standard TS-02-S1 Relative evaluation method for the stability of insolubilized soils such as heavy metals) The insolubilized waste also has such an acidic environment. It is necessary to prevent elution of heavy metals underneath.

  Therefore, a method has been proposed for suppressing the elution of harmful substances from waste even in the situation of being exposed to acid rain. In other words, technology to prevent the elution of lead and cadmium by solidifying waste incineration ash with waste clay and solidification material (Patent Document 11), adding iron salt or iron salt and mineral acid to waste such as waste incineration ash Technologies for preventing elution of heavy metals such as lead (Patent Documents 12 and 13), and methods for preventing elution of lead and cadmium from alkaline fly ash generated in an incinerator using carbon dioxide and phosphate (Patent Document 14) ) Has been reported.

Japanese Patent Laid-Open No. 10-192870 JP 2001-121133 A JP 2006-000746 A JP 2004-089816 A JP 2001-259570 A JP 2005-329343 A JP 2006-224025 A JP 2002-239522 A Japanese Unexamined Patent Publication No. 7-060222 JP 2005-279413 A JP-A-5-096263 JP-A-8-099075 JP-A-8-192128 JP-A-8-155417

However, these conventional toxic substance elution prevention techniques are merely means that use expensive components, use large-scale devices, and can suppress elution of only some toxic substances. There is a problem that elution cannot be suppressed, and the technique for preventing elution particularly in an acidic environment has problems such as a large amount of chemicals required for insolubilization and the need for special treatment equipment. Therefore, with these technologies, it has been difficult to economically and efficiently insolubilize waste containing hazardous substances and maintain the elution prevention effect in an acidic environment.
Accordingly, an object of the present invention is to provide an economical and efficient treatment technique capable of reducing the amount of elution of fluorine, boron, arsenic and selenium, which are harmful substances contained in waste, in an acidic environment to below the soil environment standard. That is. Specifically, an object of the present invention is to provide an elution inhibitor capable of suppressing elution of hazardous substances even when waste containing these hazardous substances is exposed to acid rain, and an elution prevention method using the same.

  Therefore, as a result of repeated studies, the present inventor has made calcium aluminate, aluminum sulfate, lime, and alkali metal phosphorus in the treatment of waste containing at least one selected from fluorine, boron, arsenic and selenium as harmful substances. By using a composition that combines acid salts, it was found that the amount of toxic substances released from waste can be reduced to below the soil environment standard even in an acidic environment assuming conditions of long-term exposure to acidic rain. The invention has been completed.

That is, the present invention relates to the following [1] to [5] .
[1] Containing calcium aluminate, aluminum sulfate, lime and potassium phosphate , 3 to 40 parts by mass of aluminum sulfate, 2 to 20 parts by mass of lime and 0.5 to 0.5 parts of potassium phosphate with respect to 100 parts by mass of calcium aluminate 4 mass parts, and 0.5-10 mass parts added to 100 mass parts of waste, an elution preventive agent for fluorine, boron, arsenic and selenium from waste in an acidic environment .
[2] The calcium aluminate is a crystalline calcium aluminate in which CaO and Al ₂ O ₃ are in an equimolar ratio, and the molar ratio of CaO and Al ₂ O ₃ is CaO / Al ₂ O ₃ = 1.6-2. 6. The dissolution inhibitor according to [1], comprising 6 amorphous calcium aluminate.
[3] calcium aluminate, CaO and Al ₂ O ₃ and the crystalline calcium aluminate equimolar ratio, CaO and Al ₂ O ₃ of molar ratio of _{CaO / Al 2 O 3 = 1.6~2} . 6. The dissolution inhibitor according to [1] or [2], comprising 6 amorphous calcium aluminate in a mass ratio of 100: 15 to 100: 120.
[4] The elution inhibitor according to any one of [1] to [3] is applied to a waste product whose elution amount under one or more acidic conditions selected from fluorine, boron, arsenic and selenium exceeds environmental standards. A method for preventing elution of fluorine, boron, arsenic and selenium from the waste, characterized by adding and mixing.
[5] The amount of elution in one or more acidic environments selected from fluorine, boron, arsenic and selenium is measured by the technical standard (GEPC TS-02-S1) of the soil environment center. 4. The elution prevention method according to 4.

  Waste treated with the elution inhibitor of the present invention is an economical prescription for the amount of elution in the acidic environment of fluorine, boron and heavy metals (arsenic, selenium), which are harmful substances contained in the waste. Since it can be reduced below the environmental standard, it is possible to maintain environmental safety even if it is exposed to acid rain for a long time when the waste after elution prevention treatment is used as earthwork material such as backfill material. Therefore, the present invention is an extremely useful technique for promoting effective utilization of waste such as incinerated ash contaminated with harmful substances.

The calcium aluminate used in the elution inhibitor of the present invention is basically a substance obtained by heat treating a CaO raw material and an Al ₂ O ₃ raw material. Calcium aluminate may be a hydrated active substance with a crystallized structure composed of CaO and Al ₂ O ₃ and a vitrified structure as a chemical component, and other chemical components are added in addition to CaO and Al ₂ O ₃ . It may be a compound, a solid solution, a glassy substance, or a mixture thereof. The former (crystalline) The example _{12CaO · 7Al 2 O 3, CaO} · Al 2 O 3, 3CaO · Al 2 O 3, CaO · 2Al 2 O 3, CaO · 6Al 2 O 3 and the like, the latter (Glass the quality) for _{example, 4CaO · 3Al 2 O 3 ·} SO 3, 11CaO · 7Al 2 O 3 · CaF 2, Na 2 O · 8CaO · 3Al 2 O 3 and the like.

The calcium aluminate used in the present invention is preferably one containing crystalline calcium aluminate and amorphous calcium aluminate, crystalline calcium aluminate having an equimolar ratio of CaO and Al ₂ O ₃ , CaO and More preferably, the Al ₂ O ₃ content molar ratio includes amorphous calcium aluminate with CaO / Al ₂ O ₃ = 1.6 to 2.6.

The crystalline calcium aluminate having an equimolar ratio of CaO and Al ₂ O ₃ was mixed so that the CaO source and the Al ₂ O ₃ source were equimolar ratios in terms of CaO and Al ₂ O ₃ , respectively. A thing is obtained by heating at 1600 degreeC, for example, and cooling this slowly. In addition, natural cooling in the heating device can be generally used for the slow cooling, but if a sudden temperature drop occurs due to the structure of the heating device, the heating is adjusted so that the temperature lowering rate is approximately 10 ° C./min or less. Is preferred. Although the CaO source is not particularly limited, for example, limestone powder, slaked lime and quick lime powder can be preferably mentioned, and as the Al ₂ O ₃ source, bauxite powder, aluminum hydroxide, aluminum carbonate, aluminum residual ash, alumina powder, etc. are suitable, for example. Can be listed. The crystalline calcium aluminate preferably has a Blaine specific surface area of 3000 to 10000 cm ² / g, and is preferably substantially the same as the Blaine specific surface area of the amorphous calcium aluminate used therewith.

Amorphous calcium aluminate molar ratio CaO / Al ₂ O ₃ = from 1.6 to 2.6 of CaO and Al ₂ O ₃ is, CaO source and Al ₂ O ₃ source, respectively as CaO and Al ₂ O _{What is} converted into ₃ and mixed in the range of the molar ratio is obtained by, for example, heating and melting at 1400 to 1900 ° C. and rapidly cooling it. The rapid cooling can be performed by a known rapid cooling method such as taking out the melt from the heating temperature from the furnace, quenching in water, or blowing a cooling gas. When the molar ratio of CaO to Al ₂ O ₃ (CaO / Al ₂ O ₃ ) is less than 1.6, the reactivity is lowered and the elution preventing effect may not be sufficiently obtained. On the other hand, if the molar ratio (CaO / Al ₂ O ₃ ) exceeds 2.6, vitrification requires an extremely high melting point and a rapid cooling operation from the temperature, which makes the production difficult, which is not practical. The amorphous calcium aluminate is preferably adjusted to a particle size by appropriately performing pulverization, classification, sieving, etc., and a Blaine specific surface area of 3000 to 10000 cm ² / g. Incidentally, CaO source and Al ₂ O ₃ source, the same thing can be used in the case of the crystalline calcium aluminate.

Calcium aluminate to be used in the present invention comprises a crystalline calcium aluminate of the of CaO and Al ₂ O ₃ equal molar ratio, the molar ratio of said CaO and Al ₂ O ₃ is CaO / Al ₂ O ₃ = 1 Those containing an amorphous calcium aluminate of .6 to 2.6 in a mass ratio of 100: 10 to 100: 200 are preferred, and those containing a mass ratio of 100: 15 to 100: 120 are more preferred. By using the calcium aluminate mixture of this mass ratio, the elution prevention effect with respect to the waste containing the hazardous | toxic substance in an acidic environment can be exhibited especially favorable.

The aluminum sulfate used in the present invention may be either a hydrate represented by Al ₂ (SO ₄ ) ₃ .nH ₂ O as a chemical component or an anhydrous salt represented by Al ₂ (SO ₄ ) ₃ . Preferably, a hydrate having n of 14 to 18 is preferable because it is excellent in the elution suppression effect of harmful substances.

As the lime used in the present invention, the main component is calcium oxide represented by CaO as a chemical component, or the main component is calcium hydroxide represented by Ca (OH) ₂ as a chemical component. It may include both of these. Preferably, lime having a high calcium oxide content is preferable because it is excellent in the elution suppressing effect of harmful substances. The fineness of lime is preferably 2000 cm ² / g or more as the Blaine specific surface area.

  Examples of the alkali metal phosphate used in the present invention include readily soluble salts such as sodium phosphate and potassium phosphate. In this invention, a favorable elution inhibitory effect is acquired by mix | blending an alkali metal phosphate. As the alkali metal phosphate, potassium phosphate represented by the following formulas (1) to (3) is preferable, and potassium dihydrogen phosphate represented by the following formula (2) is preferable because of its excellent elution suppression effect. More preferred.

K ₂ HPO ₄ (1)
KH ₂ PO ₄ (2)
K ₃ PO ₄ (3)

  In the dissolution inhibitor of the present invention, the mixing ratio of aluminum sulfate, lime and alkali metal phosphate is 3 to 40 parts by mass of aluminum sulfate, 2 to 20 parts by mass of lime and alkali metal phosphorus with respect to 100 parts by mass of calcium aluminate. When it mix | blends so that it may become 0.5-4 mass parts of acid salt, since a favorable elution prevention effect is acquired, it is preferable.

  Examples of the waste targeted by the elution inhibitor of the present invention include sewage sludge incineration ash, fly ash, paper sludge ash, steelmaking slag, and garbage incineration ash. Furthermore, it is preferable that the wastes are those whose elution amount of one or more selected from fluorine, boron, arsenic and selenium exceeds the environmental standard. Sewage sludge incineration ash is one that has been incinerated in order to dehydrate sewage sludge and further reduce and stabilize it. Fly ash is incinerated ash generated by the combustion of coal in a coal-fired power plant or a coal boiler. Paper sludge ash is incinerated ash generated when incinerating and reducing the volume of paper sludge discharged from a paper mill. Steelmaking slag is slag generated in a process of decarbonizing pig iron produced in a blast furnace and refining it into steel. Garbage incineration ash has been incinerated to reduce and stabilize municipal waste. These wastes preferably have a maximum particle size of 1.2 mm or less. Specific examples of earthwork materials that effectively use these wastes include backfill materials, roadbed materials, embankment materials, backing materials, soil improvement materials, road materials, admixtures for concrete products, and the like. .

  In order to treat the waste in which the harmful substances exceed the soil environment standard with the elution inhibitor of the present invention, the elution inhibitor may be added to the waste, and water may be added and mixed. The amount of the dissolution inhibitor added to the waste is preferably 0.5 to 10 parts by weight with respect to 100 parts by weight of the waste, although it depends on the content of harmful substances. It is more preferable to use parts.

  The mixing method of the elution inhibitor of the present invention, waste and water is not particularly limited. When using waste as a backfill material, a general mixer such as a pan-type mixer or a forced biaxial mixer is used on site. The elution inhibitor of the present invention, waste, and water can be mixed using, and processed into a slurry-like or massive mixture for backfilling.

  EXAMPLES Next, an Example is given and this invention is demonstrated still in detail.

(Elution inhibitor)
Using coarse crushed particles (particle size of about 1 mm or less) of limestone (CaO content; 56% by mass) as the CaO source and van earth shale (Al ₂ O ₃ content; 88% by mass) as the Al ₂ O ₃ source, Calcium aluminate powders represented by A1 to A6 were prepared. The production method is as follows: a mixture of a CaO source and an Al ₂ O ₃ source in a predetermined molar ratio is heated to 1800 ° C. (± 50 ° C.) in an electric furnace, held for 60 minutes, and then the heating is stopped and the furnace It was obtained by allowing to cool naturally (A1 to A3). Similarly, after heating to 1800 ° C. (± 50 ° C.) and holding for 60 minutes, the heated product is taken out from the electric furnace at a temperature of 1800 ° C. at room temperature, and immediately after removal, nitrogen gas is applied to the surface of the heated product at a flow rate of about 100 cc / sec. Were obtained by spraying (A4 to A6). The obtained cooled product was pulverized by a ball mill, and the fineness was adjusted by changing the pulverization time so that the specific surface area of the brane was 5000 ± 500 cm ² / g.
A1; CaO / Al ₂ O ₃ = crystalline calcium aluminate A2 in molar ratio A2; CaO / Al ₂ O ₃ = crystalline calcium aluminate A3 in molar ratio 1.7; CaO / Al ₂ O ₃ = mol A crystalline calcium aluminate A4 with a ratio of 0.5; CaO / Al ₂ O ₃ = amorphous calcium aluminate A5 with a molar ratio of 1.7; CaO / Al ₂ O ₃ = amorphous calcium with a molar ratio of 2.3 Aluminate A6; CaO / Al ₂ O ₃ = calcium aluminate with a molar ratio of 2.9 and a vitrification rate of 10%

Using materials selected from A1 to A6 calcium aluminate and B to D shown below, dry mixing was performed for 3 minutes using a Henschel mixer at a blending ratio shown in Table 2 to prepare an elution inhibitor.
B; Aluminum sulfate 14-18 hydrate: Powder reagent C manufactured by Kanto Chemical Co .; Calcium oxide: Powder reagent D manufactured by Kanto Chemical Co .; Potassium dihydrogen phosphate: Powder reagent manufactured by Kanto Chemical Co.

(waste)
・ Sewage sludge incineration ash Sewage sludge incineration ash with a maximum particle size of 1.2 mm or less was used as waste containing hazardous substances. About this sewage sludge incineration ash, in an acidic environment measured by a method in accordance with the technical standard of the Soil Environment Center (GEPC TS-02-S1: Relative evaluation method for stability of pH in insolubilized soil such as heavy metals) Table 3 shows the elution amounts of fluorine, boron, arsenic and selenium.

(Measurement of elution amount)
The elution inhibitor and water shown in Table 2 were added to the sewage sludge incineration ash at the blending ratio shown in Table 5 and mixed for 3 minutes with a mortar mixer to prepare a mixture. The mixture is enclosed in a plastic bag and cured at a temperature of 20 ° C. After a curing period of 1 or 7 days, the technical standard of the soil environment center (GEPC TS-02-S1: pH of insolubilized soil such as heavy metals) The amount of elution of fluorine, boron, arsenic and selenium in an acidic environment was measured by a method according to the method of relative evaluation of stability against change. Table 5 shows the measurement results of the elution amount.

[Method for measuring elution amount according to GEPC TS-02-S1]
(1) Roughly crush the sample after curing for a predetermined period, collect and mix the sieve 2 mm passage.
(2) Weigh 50 g of sample into a 1000 mL capacity plastic container, add 500 g of sulfuric acid aqueous solution (0.769 mmol / L) as a solvent, and shake for 6 hours with a shaker (number of shakes: 200 times / min).
(3) After allowing the polycontainer to stand for 30 minutes, the supernatant of the sample solution is filtered through a membrane filter having a pore diameter of 0.45 μm to obtain a test solution.
(4) The components of the collected test solution are measured by the method shown in Table 4.

  From the results shown in Table 5, the sewage sludge incineration ash containing the dissolution agent of the present invention has an elution amount of fluorine, boron, arsenic and selenium for soil environment standards when the curing period is 7 days. No. 46) is suppressed to a specified value or less, and it can be seen that the elution preventing effect in an acidic environment is well exhibited. No. In Examples A1 to A7 using 1 to 4 elution inhibitors, the amount of elution of fluorine, boron, arsenic, and selenium is suppressed below the specified value of the soil environment standard even when the curing period is 1 day. It turns out that especially the elution prevention effect is favorable. On the other hand, when an elution inhibitor other than the present invention is used, Except for the amount of fluorine and boron elution when the curing period of Comparative Example A3 using 12 elution inhibitors is 7 days, all of them exceeded the soil environmental standards, and elution of sewage sludge incineration ash containing harmful substances The prevention effect was insufficient.

(waste)
-Fly ash and paper sludge ash Fly ash and paper sludge ash having a maximum particle size of 1.2 mm or less were used as waste containing harmful substances. About this fly ash and paper sludge ash, the acidity measured by a method according to the technical standard of the Japan Soil Environment Center (GEPC TS-02-S1: Relative evaluation method for the stability of insolubilized soil such as heavy metals against pH change) Table 6 shows the elution amounts of fluorine, boron, arsenic, and selenium under the environment.

(Measurement of elution amount)
With respect to the above fly ash and paper sludge ash, the dissolution inhibitor shown in Table 2 and water are blended in the blending ratios shown in Table 7, and the dissolution rate measurement method (method according to GEPC TS-02-S1) is used. The elution prevention effect was evaluated. The results are shown in Table 7.

  From the results shown in Table 7, the fly ash and / or paper sludge ash containing the dissolution agent of the present invention has an elution amount of fluorine, boron, arsenic and selenium when the curing period is 7 days. (Environment Agency Notification No. 46) is suppressed below the specified value, and it can be seen that the elution prevention effect in an acidic environment is well exhibited. No. In Examples B1 to B7, B13 and B14 using 1 to 4 elution inhibitors, the elution amount of fluorine, boron, arsenic and selenium is suppressed below the specified value of the soil environment standard even when the curing period is 1 day. It can be seen that the effect of preventing elution is particularly good. On the other hand, when an elution inhibitor other than the present invention is used, Comparative Example B2 using No. 11 dissolution inhibitor and The amount of fluorine and selenium eluted when the curing period was 7 days in Comparative Example B3 using 12 dissolution inhibitors, and Except the elution amount of selenium for the curing period 1 day and the elution amount of arsenic and selenium for the curing period 7 days in Comparative Examples B8 and B9 using 12 elution inhibitors, both exceeded the soil environmental standards, The anti-elution effect on fly ash and paper sludge ash containing harmful substances was insufficient.

Claims (5)

Containing calcium aluminate, aluminum sulfate, lime and potassium phosphate , 3 to 40 parts by mass of aluminum sulfate, 2 to 20 parts by mass of lime and 0.5 to 4 parts by mass of potassium phosphate with respect to 100 parts by mass of calcium aluminate An eluting inhibitor for fluorine, boron, arsenic and selenium from waste in an acidic environment , wherein 0.5 to 10 parts by weight are added to 100 parts by weight of waste. Calcium aluminate, CaO and Al ₂ O ₃ and the crystalline calcium aluminate equimolar ratio, CaO and Al ₂ O ₃ of molar ratio of CaO / Al ₂ non of O ₃ = 1.6 to 2.6 The dissolution inhibitor according to claim 1, comprising crystalline calcium aluminate. Calcium aluminate, CaO and Al ₂ O ₃ and the crystalline calcium aluminate equimolar ratio, CaO and Al ₂ O ₃ of molar ratio of CaO / Al ₂ non of O ₃ = 1.6 to 2.6 The dissolution inhibitor according to claim 1 or 2, comprising crystalline calcium aluminate in a mass ratio of 100: 15 to 100: 120. The elution inhibitor according to any one of claims 1 to 3 is added to and mixed with waste having an amount of elution in one or more acidic environments selected from fluorine, boron, arsenic and selenium exceeding a soil environmental standard. A method for preventing elution of fluorine, boron, arsenic and selenium from the waste. 5. The amount of elution in one or more acidic environments selected from fluorine, boron, arsenic and selenium is measured by a technical standard (GEPC TS-02-S1) of the soil environment center. Elution prevention method.