Heavy metal insolubilizing material and method for solidification and insolubilization treatment

Abstract

To provide a heavy metal insolubilizing material that, even when waste or other materials capable of eluting heavy metals over time are subjected to solidification and insolubilization treatment, allows the elution level of heavy metals, after a long time has passed following the solidification and insolubilization treatment, to be reduced to or below a standard value, thereby enabling the treated material to be reused as recycled resources.SOLUTION: A heavy metal insolubilizing material including hemihydrate gypsum powder, blast furnace slag micropowder, and acidic powder, the proportion of the hemihydrate gypsum powder being 30 to 65 mass%, the proportion of the blast furnace slag micropowder being 8 to 50 mass%, and the proportion of the acidic powder being 2 to 38 mass%, based on a total of 100 mass% of the hemihydrate gypsum powder, the blast furnace slag micropowder, and the acidic powder.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to a heavy metal insolubilizing material and a solidification and insolubilization method using the heavy metal insolubilizing material. [Background technology]

[0002] Fly ash, slag, and other by-products generated by factories and other facilities may contain heavy metals in excess of the soil environmental standards, posing a problem when reusing these by-products as resources. Furthermore, soil at former factory sites may be contaminated with heavy metals, posing a problem when reusing such sites. As a countermeasure against these heavy metal contaminations, insolubilizing materials and solidification insolubilization methods for insolubilizing heavy metals have been proposed.

[0003] For example, Patent Document 1 discloses a method for solidifying and insolubilizing heavy metals and the like contained in mud using (A) calcined gypsum, (B) an aluminum compound, and (C) a compound containing a calcium component and / or a magnesium component, in which (B) an aluminum compound is used in an amount of 0.8 to 20 parts by mass relative to 100 parts by mass of (A) calcined gypsum, and (C) at least one calcium component and / or magnesium component selected from the group consisting of calcium hydroxide, calcium oxide, magnesium oxide, magnesium hydroxide, and calcium carbonate, which is a raw material for calcium oxide. The document describes a method for insolubilizing heavy metals, which comprises reacting a compound in mud in the presence of 0.08 to 15 parts by mass of a nesium component to solidify the mud, and incorporating and insolubilizing at least one heavy metal selected from the group consisting of cadmium and its compounds, hexavalent chromium compounds, cyanide compounds, mercury and its compounds (including alkyl mercury), selenium and its compounds, lead and its compounds, arsenic and its compounds, fluorine and its compounds, and boron and its compounds into the layered double hydroxide-like mineralized, monosulfate-like mineralized, or ettringite-like mineralized structure. Furthermore, Patent Document 2 describes an agent for preventing the elution of fluorine, boron, arsenic, and selenium from waste containing lime components, which contains calcium aluminate, aluminum sulfate, and potassium phosphate, and is characterized in that the molar ratio of calcium aluminate, CaO, and Al2O3 is CaO / Al2O3 = 0.5 to 2.9, and the amount added is 0.5 to 10 parts by mass per 100 parts by mass of the waste. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Patent No. 5315096 [Patent Document 2] Patent No. 6157947 Summary of the Invention [Problem to be solved by the invention]

[0005] Known insolubilizing agents are capable of insolubilizing heavy metals contained in materials that are the subject of solidification and insolubilization treatment by forming calcium hydrates such as ettringite in a relatively short time and incorporating the heavy metals into their structure. On the other hand, depending on the type of object to be solidified and insolubilized, the heavy metals contained in the object may leach out over a relatively long period of time. In such cases, the amount of heavy metals leached from the object after the solidification and insolubilization treatment (hereinafter also referred to as the "solidified and insolubilized object") may exceed the standard value when a long period of time has passed since the solidification and insolubilization treatment. Furthermore, the color of the object after solidification and insolubilization treatment may change compared to the object before solidification and insolubilization treatment, making it difficult to use the object after solidification and insolubilization treatment as a recycled material. The object of the present invention is to provide a heavy metal insolubilizing material that can reduce the amount of heavy metals leaching from the solidified and insolubilized product to a standard value or less even after a long period of time (e.g., 90 days or more) has passed since the solidification and insolubilization treatment, even when the solidified and insolubilized product is waste or the like from which heavy metals leach over a long period of time, and that can enable the solidified and insolubilized product to be used as a recycled material or the like. [Means for solving the problem]

[0006] As a result of intensive research to solve the above-mentioned problems, the present inventors have found that the above-mentioned object can be achieved by a heavy metal insolubilizing material containing hemihydrate gypsum powder, ground granulated blast furnace slag, and an acidic powder, wherein, based on the total amount (100% by mass) of the hemihydrate gypsum powder, ground granulated blast furnace slag, and acidic powder, the proportion of the hemihydrate powder is 30 to 65% by mass, the proportion of the ground granulated blast furnace slag powder is 8 to 50% by mass, and the proportion of the acidic powder is 2 to 38% by mass, and have completed the present invention. That is, the present invention provides the following [1] to [8]. [1] A heavy metal insolubilizing material comprising hemihydrate gypsum powder, ground granulated blast furnace slag, and an acidic powder, wherein, in the total amount (100% by mass) of the hemihydrate gypsum powder, ground granulated blast furnace slag, and acidic powder, the proportion of the hemihydrate gypsum powder is 30 to 65% by mass, the proportion of the ground granulated blast furnace slag powder is 8 to 50% by mass, and the proportion of the acidic powder is 2 to 38% by mass.

[0007] [2] The heavy metal insolubilizing material according to [1], further comprising a reducing powder, wherein the amount of the reducing powder is 2 to 30 parts by mass per 100 parts by mass of the total amount of the hemihydrate gypsum powder, the ground granulated blast furnace slag, and the acidic powder. [3] The heavy metal insolubilizing material according to [1] or [2], further comprising an alkaline powder, wherein the amount of the alkaline powder is 2 to 25 parts by mass per 100 parts by mass of the total amount of the hemihydrate gypsum powder, the ground granulated blast furnace slag, and the acidic powder. [4] The heavy metal insolubilizing material according to any one of [1] to [3], wherein the a value in the Hunter Lab color space of the heavy metal insolubilizing material is −0.5 or less. [5] A solidification and insolubilization method comprising mixing the heavy metal insolubilizing material according to any one of [1] to [4] above with a material to be solidified and insolubilized, thereby obtaining a solidified and insolubilized material in which the heavy metals contained in the material to be solidified and insolubilized are insolubilized. [6] The cone index of the solidified insolubilized product is 200 kN / m 2 The solidification and insolubilization method according to [5] above. [7] The solidification and insolubilization method according to [5] or [6], wherein the heavy metals contained in the insolubilization treatment object are fluorine and its compounds. [8] The solidification and insolubilization method according to [5] or [6], wherein the heavy metals contained in the insolubilization treatment object are hexavalent chromium compounds. [Effects of the Invention]

[0008] According to the heavy metal insolubilizing material of the present invention, even when the solidification and insolubilization treatment is performed on waste or the like from which heavy metals leach over a long period of time, the amount of heavy metals leaching from the solidified and insolubilized product after a long period of time has elapsed since the solidification and insolubilization treatment can be reduced to below the standard value, and the solidified and insolubilized product (the product after the solidification and insolubilization treatment) can be used as a recycled material, etc. DETAILED DESCRIPTION OF THE INVENTION

[0009] The heavy metal insolubilizing material of the present invention contains hemihydrate gypsum powder, ground granulated blast furnace slag, and acidic powder, and the proportion of the hemihydrate gypsum powder is 30 to 65 mass%, the proportion of the ground granulated blast furnace slag is 8 to 50 mass%, and the proportion of the acidic powder is 2 to 38 mass%, based on the total amount (100 mass%) of the hemihydrate gypsum powder, ground granulated blast furnace slag, and acidic powder. The proportion of the hemihydrate gypsum powder in the total amount (100% by mass) of the hemihydrate gypsum powder, ground granulated blast furnace slag, and acidic powder is 30 to 65% by mass, preferably 38 to 60% by mass, more preferably 40 to 58% by mass, and particularly preferably 48 to 56% by mass. If the proportion is less than 30% by mass, the amount of heavy metals eluted from the solidified and insolubilized product increases. If the proportion is more than 65% by mass, the amount of heavy metals eluted from the solidified and insolubilized product increases over a long period of time after the solidification and insolubilization treatment.

[0010] The Blaine specific surface area of the hemihydrate gypsum is preferably 1,000 to 5,000 cm 2 / g, more preferably 1,500 to 4,500 cm 2 / g, and particularly preferably 2,000 to 4,200 cm 2 / g. The above Blaine specific surface area is 1,000 cm 2 / g or more, the amount of heavy metals eluted from the solidified and insolubilized product can be further reduced. 2 If the content is 0.1g or less, the labor required to obtain the material is small and the cost does not become excessive.

[0011] The proportion of ground granulated blast furnace slag in the total amount (100% by mass) of hemihydrate gypsum powder, ground granulated blast furnace slag, and acidic powder is 8 to 50% by mass, preferably 15 to 48% by mass, more preferably 25 to 45% by mass, and particularly preferably 38 to 42% by mass. If the proportion is less than 8% by mass, the amount of heavy metals eluted from the solidified and insolubilized product increases over a long period of time after the solidification and insolubilization treatment. If the proportion exceeds 50% by mass, the amount of heavy metals eluted from the solidified and insolubilized product increases. Examples of ground blast furnace slag include fine powders such as granulated slag obtained by quenching with water and crushing molten slag, which is a by-product of producing pig iron in a blast furnace, and slowly cooled slag obtained by crushing the molten slag. These may be used alone or in combination of two or more.

[0012] The Blaine specific surface area of the ground granulated blast furnace slag is preferably 3,000 to 10,000 cm 2 / g, more preferably 3,500 to 9,500 cm 2 / g, particularly preferably 4,000 to 9,000 cm 2 / g. The specific surface area of the above Blaine is 3,000 cm 2 / g or more, the amount of heavy metals eluted from the solidified and insolubilized product can be further reduced. 2If the content is 0.1g or less, the labor required to obtain the material is small and the cost does not become excessive.

[0013] The proportion of the acidic powder in the total amount (100% by mass) of the hemihydrate gypsum powder, ground granulated blast furnace slag, and acidic powder is 2 to 38% by mass, preferably 3 to 32% by mass, more preferably 4 to 25% by mass, even more preferably 5 to 15% by mass, and particularly preferably 5 to 10% by mass. If the proportion is less than 2% by mass, the amount of heavy metals eluted from the solidified and insolubilized product increases. If the proportion is more than 38% by mass, the amount of heavy metals eluted from the solidified and insolubilized product increases over a long period of time after the solidification and insolubilization treatment. In this specification, the term "acidic powder" refers to a powdered acidic substance. Also, the term "acidic substance" refers to a substance that, when dissolved in water, has an aqueous solution with a pH of less than 7.0. Examples of acidic substances constituting the acidic powder include sulfates such as aluminum sulfate; nitrates such as potassium nitrate and sodium nitrate; acetates such as aluminum acetate, sodium acetate, and potassium acetate; phosphates such as sodium dihydrogen phosphate; metal chlorides such as aluminum chloride and iron (III) chloride; and organic acids such as carboxylic acids (e.g., acetic acid) and citric acid. These may be used alone or in combination of two or more. These may also be in the form of hydrates. Among these, aluminum sulfate and aluminum chloride are preferred, and aluminum sulfate is more preferred, from the viewpoints of ease of availability and further suppression of elution of heavy metals.

[0014] The heavy metal insolubilizing material may further contain a reducing powder, which reduces heavy metals (especially hexavalent chromium compounds) from the object of solidification and insolubilization treatment, such as waste, thereby making it possible to further reduce the amount of heavy metals leaching out. In this specification, the term "reducing powder" refers to a reducing substance in powder form. Examples of reducing substances constituting the reducing powder include metals such as iron and aluminum; sulfur compounds such as sulfur dioxide and sulfur; divalent iron compounds such as ferrous sulfate, ferrous nitrate, and ferrous chloride; divalent tin compounds such as tin chloride; metal sulfides such as iron disulfide, sodium sulfide, potassium sulfide, and calcium sulfide; thiosulfates such as potassium thiosulfate and sodium thiosulfate; sulfites such as potassium sulfite, calcium sulfite, and sodium sulfite; coal; reducing sugars such as glucose; and organic compounds such as ascorbic acid. These may be used alone or in combination of two or more. These may also be in the form of a hydrate. Among these, from the viewpoints of easy availability and further suppressing the elution of heavy metals, divalent iron compounds are preferred, and ferrous sulfate is more preferred. In this specification, the reducing powder does not include ground granulated blast furnace slag.

[0015] The amount of reducing powder is preferably 2 to 30 parts by mass, more preferably 4 to 28 parts by mass, even more preferably 6 to 25 parts by mass, and particularly preferably 8 to 22 parts by mass, relative to 100 parts by mass of the total amount of hemihydrate gypsum powder, ground granulated blast furnace slag, and acidic powder. When the amount is within the above range, the amount of heavy metals (especially hexavalent chromium compounds) leaching from the solidified insolubilized product is reduced. Furthermore, by setting the amount to 30 parts by mass or less, the b value in the Hunter Lab color space of the solidified insolubilized product can be reduced (e.g., 1.5 or less), making it easier to reuse the solidified insolubilized product as a resource. Furthermore, excessive material costs can be prevented.

[0016] The heavy metal insolubilizer may further contain an alkaline powder. By containing the alkaline powder, it is possible to further reduce the amount of heavy metals eluted from the solidified insolubilized product over a long period of time after the solidification insolubilization treatment and to improve the strength of the solidified insolubilized product. In particular, when the target of the solidification insolubilization treatment is a neutral or acidic waste, it is preferable that the heavy metal insolubilizer contain an alkaline powder. The amount of alkaline powder is preferably 2 to 25 parts by mass, more preferably 3 to 15 parts by mass, and particularly preferably 4 to 10 parts by mass, relative to 100 parts by mass of the total amount of hemihydrate gypsum powder, ground granulated blast furnace slag, and acidic powder. When the amount is within the above range, the strength of the solidified insolubilized product is improved, and the amount of heavy metals eluted from the solidified insolubilized product is reduced. Furthermore, by setting the amount to 25 parts by mass or less, excessive material costs can be prevented.

[0017] In this specification, the term "alkaline powder" refers to a powdered alkaline substance, and the term "alkaline substance" refers to a substance that dissolves in water and forms an aqueous solution with a pH of more than 7.0. Examples of alkaline substances constituting the alkaline powder include magnesium oxide-containing substances, magnesium hydroxide, quicklime, slaked lime, sodium carbonate, sodium hydrogen carbonate (sodium bicarbonate), potassium carbonate, and potassium hydrogen carbonate. These may be used alone or in combination of two or more. Examples of magnesium oxide-containing substances include light-burned magnesia, partial hydrate of light-burned magnesia, light-burned dolomite, and partial hydrate of light-burned dolomite. Among these, magnesium oxide-containing substances are preferred from the viewpoints of ease of availability and further suppression of elution of heavy metals.

[0018] The magnesium oxide content in the magnesium oxide-containing substance is preferably 65% by mass or more, more preferably 75% by mass or more, even more preferably 80% by mass or more, and particularly preferably 85% by mass or more. If the content is 20% by mass or more, the amount of heavy metals eluted from the solidified and insolubilized product is further reduced. The Blaine specific surface area of the magnesium oxide-containing material is preferably 2,000 to 10,000 cm 2 / g, more preferably 3,000 to 9,000 cm 2 / g, particularly preferably 4,000 to 8,000 cm 2 / g. The specific surface area is 2,000 cm 2 / g or more, the amount of heavy metals eluted from the solidified and insolubilized product can be further reduced. 2 If the content is 0.1g or less, the labor required to obtain the material is small and the cost does not become excessive. In this specification, the alkaline powder does not include ground granulated blast furnace slag.

[0019] In order to further reduce the amount of heavy metals eluted, the total proportion of the above-mentioned hemihydrate gypsum powder, ground granulated blast furnace slag, acidic powder, reducing powder, and alkaline powder in 100% by mass of the heavy metal insolubilizing material is preferably 95% by mass or more, more preferably 98% by mass or more, and particularly preferably 100% by mass. Furthermore, from the viewpoint of further reducing the amount of heavy metals eluted from the solidified and insolubilized product over a long period of time after the solidification and insolubilization treatment, it is preferable that the heavy metal insolubilizing material does not contain cement.

[0020] The a value of the heavy metal insolubilizing agent in the Hunter Lab color space is preferably -0.5 or less, more preferably -3.0 to -1.0, and particularly preferably -2.0 to -1.4. If the a value is -0.5 or less, the b value of the solidified insolubilized product in the Hunter Lab color space can be made smaller (for example, 2.0 or less), and adverse effects such as changes in color can be reduced when the solidified insolubilized product is used as a resource such as a raw material for cement clinker or a cement admixture, making it easier to reuse the solidified insolubilized product.

[0021] The heavy metal insolubilizing material of the present invention is preferably in the form of a powder or granule, from the viewpoint of further reducing the amount of heavy metals eluted from the material to be treated. Here, in this specification, "granular" means an aggregate of powdery materials (those with a particle size of less than 0.1 mm; powder), an aggregate of granular materials (those with a particle size of 0.1 mm or more; granules), or an aggregate containing powdery and granular materials. Also, "granular material" means an aggregate of powder, an aggregate of granules, or an aggregate containing powder and granules. Also, "particle size" means a size corresponding to the size of the sieve openings. For example, a particle size of 0.6 mm or less means that the material will pass through a sieve with 0.6 mm openings.

[0022] The object to be solidified and insolubilized (object to be solidified and insolubilized) contains heavy metals. In this specification, "heavy metals" refers to Type 2 specified hazardous substances as defined in the Soil Contamination Countermeasures Act (2003). Specifically, these include cadmium and its compounds, cyanide compounds, hexavalent chromium compounds, mercury and its compounds, selenium and its compounds, lead and its compounds, arsenic and its compounds, fluorine and its compounds, and boron and its compounds. One or more of these may be contained in the waste. Although fluorine and boron are not heavy metal elements, these elements and their compounds are considered to be included in heavy metals. Among heavy metals, hexavalent chromium compounds, arsenic and its compounds, and fluorine and its compounds may be eluted from the solidification / insolubilization treatment object over a long period of time, and therefore are suitable as the object of the solidification / insolubilization treatment in the present invention, with fluorine and its compounds being more suitable.

[0023] From the viewpoint of further reducing the amount of heavy metals eluted from the solidified and insolubilized product over a long period of time after the solidification and insolubilization treatment, the solidified and insolubilized product is preferably alkaline. The pH of the material to be solidified and insolubilized is preferably 9.0 or higher, more preferably 9.5 or higher, and particularly preferably 10.0 or higher. The above pH is the pH of the test solution prepared when measuring the amount of eluted heavy metals in accordance with Notification No. 46 of the Ministry of the Environment.

[0024] Examples of materials to be solidified and insolubilized include waste materials and soil. In this specification, waste refers to industrial waste or general waste. Industrial waste refers to waste generated as a result of business activities. Examples of industrial waste include raw concrete sludge, various sludges (e.g., sewage sludge, water purification sludge, steelmaking sludge, etc.), construction waste, concrete waste, various incineration ash (e.g., coal ash, chicken manure ash, livestock manure ash, biomass ash, sludge incineration ash), foundry sand, rock wool, waste glass, secondary blast furnace ash, various by-products (pulverized slag, etc.), and unused resources (unused remaining materials, etc.). Municipal waste refers to waste other than industrial waste. Examples of municipal waste include dried sewage sludge, municipal waste incineration ash, and seashells.

[0025] By mixing the above-mentioned heavy metal insolubilizing agent with the object to be solidified and insolubilized, the heavy metals contained in the object to be solidified and insolubilized can be insolubilized. In addition, by solidifying the object to be solidified and insolubilized, the strength (e.g., Cone Index) of the object after the solidification and insolubilization treatment (solidified and insolubilized object) can be increased. The amount of heavy metal insolubilizer per 100 parts by mass of the solidified insolubilization treatment object is preferably 0.1 to 20 parts by mass, more preferably 0.5 to 15 parts by mass, even more preferably 0.8 to 10 parts by mass, and particularly preferably 2 to 8 parts by mass. If the amount is 0.1 part by mass or more, the amount of heavy metals eluted from the solidified insolubilization treatment object can be further reduced. If the amount is 20 parts by mass or less, an excessive increase in the cost of the heavy metal insolubilizer can be prevented. Furthermore, from the viewpoint of further reducing the amount of heavy metals leaching from the solidified insolubilization treatment object, water may be added to the solidified insolubilization treatment object before mixing, and then the heavy metal insolubilizing material and the solidified insolubilization treatment object may be mixed. The amount of water per 100 parts by mass of the solidified insolubilization treatment object varies depending on the type and properties of the solidified insolubilization treatment object, but is preferably 100 parts by mass or less, more preferably 80 parts by mass or less, even more preferably 60 parts by mass or less, and particularly preferably 50 parts by mass or less.

[0026] The b value of the solidified insolubilized product in the Hunter Lab color space is preferably 2.0 or less, more preferably −1.0 to 1.5, and particularly preferably −0.5 to 1.0. If the b value is 2.0 or less, adverse effects such as changes in color can be reduced when the solidified insolubilized product is used as a resource such as a raw material for cement clinker or a cement admixture, and the solidified insolubilized product can be easily reused. From the viewpoint of further reducing the amount of heavy metals eluted from the solidified and insolubilized product over a long period of time after the solidification and insolubilization treatment, the solidified and insolubilized product is preferably alkaline. The cone index of the solidified insolubilized product is preferably 200 kN / m, for example, as a value measured 7 days after the solidification and insolubilization treatment. 2 More preferably, 250 kN / m 2 More preferably, 300 kN / m or more 2 The cone index is 200kN / m or more. 2 If the above conditions are met, when the object to be solidified and insolubilized is soft ground or the like, the strength of the ground after the solidification and insolubilization treatment can be made sufficient. [Example]

[0027] The present invention will be specifically described below with reference to examples, but the present invention is not limited to these examples. [Materials used] (1) Hemihydrate gypsum powder; manufactured by Chiyoda Ute Co., Ltd., Blaine specific surface area: 3,140 cm 2 / g (2) Blast furnace slag powder; DC Corporation, trade name "Cerament CR", Blaine specific surface area: 4,050 cm 2 / g (3) Acidic Powder A: Aluminum sulfate, manufactured by Taimei Chemical Co., Ltd., containing aluminum sulfate, several types of aluminum sulfate hydrate, the average of which is aluminum sulfate 14-hydrate. (4) Acidic Powder B: Aluminum chloride, Fujifilm, manufactured by Wako Pure Chemical Industries, Ltd., hexahydrate (5) Acidic Powder C: Sodium dihydrogen phosphate, Fujifilm, manufactured by Wako Pure Chemical Industries, Ltd. (6) Acidic Powder D; Citric Acid, manufactured by Japan Salt Co., Ltd., food additive, anhydrous (7) Reducing powder A: ferrous sulfate, manufactured by Fuji Titanium Industry Co., Ltd., monohydrate (8) Reducing powder B: ferrous chloride, manufactured by Kokusan Chemical Co., Ltd., tetrahydrate (9) Reducing Powder C; Sodium sulfite, manufactured by Hayashi Pure Chemical Industries, Ltd., Grade 1, for research and experiment use (10) Reducing Powder D;D(+)-Glucose, manufactured by Hayashi Pure Chemical Industries, Ltd., Grade 1, for research and experiment use (11) Reducing Powder E; L(+)-Ascorbic Acid, Hayashi Pure Chemical Industries, Ltd., Special Grade, for Research and Experiments (12) Alkaline powder A: Magnesium oxide-containing substance, manufactured by Taiheiyo Cement Corporation, light-burned magnesia, magnesium oxide content: 88% by mass or more (13) Alkaline Powder B; Quicklime, Sanyo Taiheiyo Lime Co., Ltd., No. 1, Powder (14) Alkaline powder C; slaked lime, manufactured by Okutama Kogyo Co., Ltd. (15) Alkaline powder D; sodium bicarbonate, manufactured by AGC, for general industrial use (16) Waste A: Sludge (elution amount of fluorine and its compounds: 1.4 mg / L, elution amount of hexavalent chromium compounds: 0.09 mg / L, pH of test solution: 10.7, Cone index: 1600 kN / m 2 (above the upper measurement limit) (17) Waste B: Slag pulverized material (elution amount of fluorine and its compounds: 1.8 mg / liter, elution amount of hexavalent chromium compounds: 0.22 mg / liter, pH: 11.9, Cone index: 1600 kN / m 2 (above the upper measurement limit) (18) Waste C: Incineration ash (elution amount of fluorine and its compounds: 1.8 mg / liter, elution amount of arsenic and its compounds: 0.07 mg / liter, pH: 12.4, Cone index: 1600 kN / m 2 (above the upper measurement limit) (19) Soil: Mud (elution of fluorine and its compounds: 2.5 mg / L, elution of hexavalent chromium compounds: 0.06 mg / L, pH: 4.3, Cone Index: 63 kN / m 2 ) The amounts of heavy metals leached from wastes A to C and soil were measured in accordance with Ministry of the Environment Notification No. 46. The pH of wastes A to C and soil is the pH of the test solution used in the above measurements. The cone index of wastes A to C and soil was measured in accordance with JIS A 1228:2020 (Test method for cone index of compacted soil).

[0028] [Examples 1 to 8, Comparative Examples 1 to 6] The types and amounts of materials shown in Table 1 were mixed to prepare a powdery heavy metal insolubilizing material. Three parts by mass of water were added to 100 parts by mass of waste A and mixed. Five parts by mass of heavy metal insolubilizer were added to 100 parts by mass of the resulting mixture and mixed, thereby carrying out a solidification and insolubilization treatment. After the solidification and insolubilization treatment, waste A was stored in a polyethylene bag, and the amount of fluorine and its compounds leached from waste A at 7 and 91 days (shown as "fluorine leaching amount" in Table 1) and the amount of hexavalent chromium compounds leached from waste A (shown as "hexavalent chromium leaching amount" in Table 1) were measured in accordance with Ministry of the Environment Notification No. 46. The results are shown in Table 1.

[0029] [Table 1]

[0030] From Table 1, it can be seen that the elution amounts of fluorine and its compounds (7 days: 0.57 to 0.80 mg / liter, 91 days: 0.38 to 0.72 mg / liter) and the elution amounts of hexavalent chromium compounds (7 days: less than 0.02 mg / liter, 91 days: less than 0.02 mg / liter) in Examples 1 to 8 respectively satisfied the elution standard values for fluorine and its compounds (0.8 mg / liter or less) and hexavalent chromium compounds (0.05 mg / liter or less) specified in Ministry of the Environment Notification No. 18. It is also clear that the amount of fluorine and its compounds eluted at a material age of 91 days is smaller than the amount of fluorine and its compounds eluted at a material age of 7 days. On the other hand, it can be seen that the amount of hexavalent chromium compounds eluted in Comparative Example 1 (7 days: 0.07 mg / liter, 91 days: less than 0.06 mg / liter) does not meet the elution standard value for hexavalent chromium compounds specified in Ministry of the Environment Notification No. 18. It can be seen that the amount of elution of fluorine and its compounds at an age of 91 days (0.81 mg / liter) and the amount of elution of hexavalent chromium compounds at an age of 7 days (0.06 mg / liter) of Comparative Example 2 do not satisfy the elution standard values for fluorine and its compounds and hexavalent chromium compounds specified in Ministry of the Environment Notification No. 18, respectively. It can be seen that the amount of fluorine and its compounds leached in Comparative Example 3 (7 days: 1.00 mg / liter, 91 days: 1.00 mg / liter) does not meet the leaching standard value for fluorine and its compounds stipulated in Ministry of the Environment Notification No. 18. It can be seen that the amount of fluorine and its compounds leached in Comparative Example 4 (7 days: 1.10 mg / liter, 91 days: 0.88 mg / liter) does not meet the leaching standard value for fluorine and its compounds stipulated in Ministry of the Environment Notification No. 18. It can be seen that the elution amounts of fluorine and its compounds in Comparative Example 5 (7 days: 1.20 mg / liter, 91 days: 1.30 mg / liter) and the elution amounts of hexavalent chromium compounds (7 days: 0.06 mg / liter, 91 days: 0.07 mg / liter) do not satisfy the elution standards for fluorine and its compounds and hexavalent chromium compounds specified in Ministry of the Environment Notification No. 18, respectively. It can be seen that the amount of hexavalent chromium compounds eluted from Comparative Example 6 at the age of 7 days (0.07 mg / liter) does not meet the elution standard value for hexavalent chromium compounds stipulated in Notification No. 18 of the Ministry of the Environment.

[0031] [Examples 9 to 14] The types and amounts of materials shown in Table 2 were mixed to prepare a powdery heavy metal insolubilizing material. 10 parts by mass of water was added to 100 parts by mass of waste B and mixed. A heavy metal insolubilizer was added in an amount equivalent to 1 part by mass per 100 parts by mass of the resulting mixture, and the mixture was mixed to carry out a solidification and insolubilization treatment. After the solidification and insolubilization treatment, waste B was stored in a polyethylene bag, and the amount of fluorine and its compounds eluted from waste B at 7 days and 91 days (shown as "fluorine elution amount" in Table 3) and the amount of hexavalent chromium compounds eluted from waste B (shown as "hexavalent chromium elution amount" in Table 3) were measured in accordance with Ministry of the Environment Notification No. 46. The results are shown in Table 3. Furthermore, the L value, a value, and b value in the Hunter color space of the heavy metal insolubilizing material, as well as the L value, a value, and b value in the Hunter color space of waste B after solidification and insolubilization treatment, were measured using a color difference meter. Table 2 shows the L value, a value, and b value in the Hunter color space of the heavy metal insolubilizing material, and Table 3 shows the L value, a value, and b value in the Hunter color space of waste B after insolubilization treatment.

[0032] [Table 2]

[0033] [Table 3]

[0034] From Table 3, it can be seen that the elution amounts of fluorine and its compounds (7 days: 0.38 to 0.77 mg / L, 91 days: 0.32 to 0.65 mg / L) and the elution amounts of hexavalent chromium compounds (7 days: less than 0.02 mg / L to 0.04 mg / L, 91 days: less than 0.02 mg / L to 0.04 mg / L) of Examples 9 to 14 respectively meet the elution standards for fluorine and its compounds and hexavalent chromium compounds specified in Ministry of the Environment Notification No. 18. It can also be seen that the elution amounts of fluorine and its compounds at an age of 91 days are smaller than the elution amounts of fluorine and its compounds at an age of 7 days. Furthermore, the b value in the Hunter color space of waste B after solidification and insolubilization treatment is -0.3 to 0.6, meaning that it has a light color, and even if it is reused as a raw material for cement clinker or a cement admixture, there will be no adverse effects due to changes in color.

[0035] [Examples 15 to 19] The types and amounts of materials shown in Table 4 were mixed to prepare a powdery heavy metal insolubilizing material. 35 parts by mass of water was added to 100 parts by mass of waste C and mixed. 7 parts by mass of heavy metal insolubilizer was added to 100 parts by mass of the resulting mixture and mixed, thereby carrying out a solidification and insolubilization treatment. After the solidification and insolubilization treatment, waste C was stored in a polyethylene bag, and the amount of fluorine and its compounds leached from waste C (shown as "fluorine leaching amount" in Table 5), the amount of arsenic and its compounds leached from waste C (shown as "arsenic leaching amount" in Table 5), and the amount of hexavalent chromium compounds leached from waste C (shown as "hexavalent chromium leaching amount" in Table 5) were measured at 7 and 91 days of age in accordance with Ministry of the Environment Notification No. 46. The results are shown in Table 5.

[0036] [Table 4]

[0037] [Table 5]

[0038] From Table 5, it can be seen that the elution amounts of fluorine and its compounds (7 days: 0.57 to 0.76 mg / liter, 91 days: 0.32 to 0.52 mg / liter), the elution amounts of arsenic and its compounds (7 days: less than 0.001 mg / liter to 0.010 mg / liter, 91 days: less than 0.001 mg / liter to 0.009 mg / liter), and the elution amounts of hexavalent chromium compounds (7 days: less than 0.02 mg / liter to 0.04 mg / liter, 91 days: less than 0.02 mg / liter to 0.03 mg / liter) of Examples 15 to 19 respectively meet the elution standard values for fluorine and its compounds, the elution standard value for arsenic and its compounds (0.01 mg / liter or less), and the elution standard value for hexavalent chromium compounds specified in Ministry of the Environment Notification No. 18. It is also found that the amounts of fluorine and its compounds, arsenic and its compounds, and hexavalent chromium compounds eluted at a material age of 91 days are equal to or smaller than the amounts of fluorine and its compounds, arsenic and its compounds, and hexavalent chromium compounds eluted at a material age of 7 days, respectively.

[0039] [Examples 20 to 23] The types and amounts of materials shown in Table 6 were mixed to prepare a powdery heavy metal insolubilizing material. Solidification and insolubilization treatment was performed by adding 3 parts by mass of heavy metal insolubilizer to 100 parts by mass of soil and mixing. After solidification and insolubilization treatment, specimens were prepared in accordance with JIS A 1228:2020 (Cone Index Test Method for Compacted Soil). The specimens were sealed with polyethylene wrap and stored, after which the Cone Index was measured at 7 and 91 days. After measuring the Cone Index, the amount of fluorine and its compounds leached from the soil (shown as "Fluorine Leaching Amount" in Table 7) and the amount of hexavalent chromium compounds leached from the specimens (shown as "Hexavalent Chromium Leaching Amount" in Table 7) were measured in accordance with Ministry of the Environment Notification No. 46. The results are shown in Tables 6 to 8.

[0040] [Table 6]

[0041] [Table 7]

[0042] From Table 7, it can be seen that the elution amounts of fluorine and its compounds in Examples 20 to 23 (7 days: 0.51 to 0.75 mg / liter, 91 days: 0.38 to 0.49 mg / liter) and the elution amounts of hexavalent chromium compounds (7 days: less than 0.02 mg / liter, 91 days: less than 0.02 mg / liter) each satisfy the elution standard value for fluorine and its compounds (0.8 mg / liter or less) specified in Ministry of the Environment Notification No. 18. It can also be seen that the amount of fluorine and its compounds leached and the amount of hexavalent chromium compounds leached at a material age of 91 days are equal to or smaller than the amount of fluorine and its compounds leached and the amount of hexavalent chromium compounds leached at a material age of 7 days, respectively. In addition, the cone index (7 days: 320 to 750 kN / m 2 , 91 days: 870kN / m 2 ~1600kN / m 2 or more) are equivalent to Class 4 construction waste soil to Class 2 construction waste soil (200kN / m 2 It can be seen that the above applies. It can also be seen that the cone indexes at 91 days of age are greater than those at 7 days of age.

Claims

1. The composition includes hemihydrate gypsum powder, ground granulated blast furnace slag, and acid powder, A heavy metal insolubilizing material characterized in that, in the total amount (100% by mass) of the hemihydrate gypsum powder, the ground granulated blast furnace slag, and the acidic powder, the proportion of the hemihydrate gypsum powder is 30 to 65% by mass, the proportion of the ground granulated blast furnace slag is 8 to 50% by mass, and the proportion of the acidic powder is 2 to 38% by mass.

2. The heavy metal insolubilizer according to claim 1, further comprising a reducing powder, and the amount of the reducing powder is 2 to 30 parts by mass per 100 parts by mass of the total amount of the hemihydrate gypsum powder, the ground granulated blast furnace slag, and the acidic powder.

3. 3. The heavy metal insolubilizing material according to claim 1 or 2, further comprising an alkaline powder, and the amount of the alkaline powder is 2 to 25 parts by mass per 100 parts by mass of the total amount of the hemihydrate gypsum powder, the ground granulated blast furnace slag, and the acidic powder.

4. 3. The heavy metal insolubilizing material according to claim 1, wherein the a value in the Hunter Lab color space of said heavy metal insolubilizing material is −0.5 or less.

5. 3. A method for solidification and insolubilization, comprising mixing the heavy metal insolubilizing material according to claim 1 or 2 with a material to be solidified and insolubilized, to obtain a solidified and insolubilized material in which the heavy metals contained in the material to be solidified and insolubilized are insolubilized.

6. The cone index of the solidified insolubilized product is 200 kN / m ２ The solidification and insolubilization method according to claim 5, wherein the solidification and insolubilization method is as described above.

7. 6. The solidification and insolubilization method according to claim 5, wherein the heavy metals contained in the material to be insolubilized are fluorine and its compounds.

8. 6. The solidification and insolubilization method according to claim 5, wherein the heavy metals contained in the material to be insolubilized are hexavalent chromium compounds.

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