JP2001070926A - Hazardous substance fixing material - Google Patents

Abstract

PROBLEM TO BE SOLVED: To inexpensively and surely fix hazardous substances such as heavy metals by mixing a substance having a rehydration property, obtained by heating treatment of calcium sulfoaluminate hydrate, and one or more kinds among an inorganic acid salt of iron, a sulfide or hydrosulfide of an alkali metal or an alkaline earth metal, and a thiourea. SOLUTION: For producing a fixing material, first of all calcium sulfoaluminate hydrate is synthesized and then is subjected to a heating treatment, so that its crystal structure is destroyed and converted to an amorphous state. Subsequently the substance after the heating treatment is mixed with one or more kinds among an inorganic acid salt of iron, a sulfide or hydrosulfide of an alkali metal or an alkaline earth metal, and a thiourea, thereby improving a hazardous substances fixing property. At this time, selecting the materials under condition that they are available and inexpensive, iron sulfate is preferable as the inorganic acid salt of iron, and sodium sulfide, calcium sulfide, etc., are preferable as the sulfide or hydrosulfide of the alkali metal or the alkaline earth metal. As a result, hazardous substances such as heavy metals are fixed surely and inexpensively to be detoxified.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION Waste, sludge, and contaminated soil generated during the redevelopment of urban areas are increasing as a result of our industrial and living activities. There is an urgent need for landfill or reuse. The present invention provides a material that stabilizes harmless substances contained in such wastes, sludge, and contaminated soil generated at the time of redevelopment of a city, thereby stabilizing the harmful substances, and enabling landfill disposal or reuse. Is what you do.

[0002]

2. Description of the Related Art Conventionally, as a method for detoxifying harmful substances (mainly heavy metals) contained in waste, sludge, and contaminated soil generated at the time of redevelopment of a city, a solidification method has been used. Solidification technology includes cement solidification,
There are methods such as asphalt solidification and melt solidification. Also,
There is also a method of chemical treatment in which a liquid chelating agent is reacted with heavy metals in waste to form an insoluble heavy metal chelating compound.

[0003] For the solidification treatment with cement, a method is widely used in which waste and cement are weighed so as to have a predetermined ratio, a predetermined amount of water is added, and the mixture is kneaded and molded.
In the solidification treatment with cement, the effect of insolubilizing heavy metals as a stable hydroxide by an alkali component in the cement and the effect of adsorption and physical containment accompanying the solidification of the cement are used for immobilization. Therefore, the harmful substances to be solidified are heavy metals such as cadmium, lead, mercury, arsenic, and selenium, and it is difficult to solidify such as cyanogen and hexavalent chromium, and treat waste containing such harmful substances. Pre-processing is required in the case. Further, the Environment Agency Notification No. 5, as the "Standards for solid of waste containing metal or the like", it is shown that the addition of 1 m ³ per 150kg or more hydraulic cement.

Solidification by asphalt focuses on excellent asphalt adhesiveness, impregnation, water repellency, water resistance and chemical resistance, and is kneaded with waste to prevent contact with water. This is a treatment method that suppresses the elution of harmful substances. Solidification with asphalt is performed for sludge, radioactive waste, refuse incineration ash, etc. However, due to the cost and inadequate handling of asphalt, there are few cases where it is implemented compared to the cement method.

[0005] In the melting treatment, the waste is reduced to 1400 to 1600.
By heating to a high temperature of ° C., organic matter is decomposed and sealed and fixed in slag that generates heavy metals. This method is considered to have the highest safety, but heavy metals with relatively low boiling points such as mercury, lead, arsenic, and cadmium volatilize in the gas during the melting process and are collected as fly ash. Is disadvantageous in that a new processing problem occurs. Another problem is that the processing cost is the highest.

The immobilization with a liquid chelating agent involves kneading a nitrogen and sulfur organic chelating agent or a sulfur-free inorganic chemical with waste to immobilize heavy metals, but the chelating agent is expensive. For this reason, it is common to use it together with cement solidification. In the case of an organic chelating agent, there is a problem in terms of long-term stability (for example, acid rain and biodegradability).

[0007]

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and has as its object to provide an inexpensive material for fixing harmful substances which stably fixes heavy metals over a long period of time.

[0008]

The harmful substance fixing material according to the present invention comprises a rehydratable substance obtained by heat treatment of calcium sulfoaluminate hydrate, an inorganic acid salt of iron, and an alkali metal. Alternatively, it is a mixture with at least one of sulfide or hydrosulfide of alkaline earth metal and thiourea.

In order to produce the immobilizing material of the present invention, it is necessary to first synthesize calcium sulphoaluminate hydrate as a starting material. Calcium sulfoaluminate hydrate includes trisulfate type (3CaO.Al ₂ O ₃
· 3CaSO ₄ · _32H 2 O) and mono sulfate type _{(3CaO · Al 2 O 3 ·} CaSO 4 · 12H 2 O)
Exists. The trisulfate type is called ettringite, which is naturally produced and can be used as a raw material of the present invention. These calcium sulfoaluminate hydrates can be obtained by a wet method of synthesizing a solution or a slurry, or a solid-phase method of synthesizing by mixing and baking and hydrating raw materials. However, in consideration of economy, it is preferable to apply a wet method with low heat energy cost.

Since the effect of immobilizing harmful substances cannot be expected even if this calcium sulfoaluminate hydrate is added to waste as it is, the calcium sulfoaluminate hydrate is heat-treated to remove the amorphous structure. Need to be in quality. Heat treatment is performed at a temperature of 150 ° C. or more for ettringite and 200 ° C. or more for monosulfate. By this heat treatment, the calcium sulfoaluminate hydrate becomes an amorphous state in which the attached water and the water of crystallization are desorbed and the crystal structure is broken. These heat-treated products easily react with water (rehydration reaction) to return to the original calcium sulfoaluminate hydrate. Heat treatment temperature is 4
When the temperature exceeds 00 ° C., gypsum is released and crystallized, but this does not affect the performance of the fixing material. Heat treatment at a high temperature does not affect the performance of the harmful substance as an immobilizing material, but when heated at 1000 ° C. or more, part of the gypsum decomposes into quicklime and sulfur trioxide (SO ₃ ). Cause SO ₃
It is preferable to perform the heat treatment at as low a temperature as 1000 ° C. or less in consideration of the volatilization resulting in a disorder in the composition or the heat energy cost.

Heat-treated calcium sulfoaluminate hydrate (hereinafter simply referred to as a heat-treated product) efficiently fixes heavy metals. It is not easy to immobilize heavy metals to fill.

Therefore, an inorganic acid salt of iron,
By adding and using one or more of a sulfide or hydrosulfide of an alkali metal or an alkaline earth metal and thiourea, the ability to immobilize harmful substances can be improved. On the condition that it is easily available and inexpensive, iron sulfate or iron chloride is preferred as the inorganic acid salt of iron, and sodium sulfide, sodium polysulfide, sodium sulfide as sulfides or hydrosulfides of alkali metals or alkaline earth metals. Calcium, calcium polysulfide, sodium bisulfide, calcium bisulfide and the like are preferably used. These drugs basically react with heavy metals to form poorly soluble compounds with low solubility. The amount of these additives is 5 to 30 parts by weight of the inorganic acid salt of iron, sulfide or hydrosulfide of alkali metal or alkaline earth metal, and thiourea is 0 to 100 parts by weight of the object to be fixed. 0.5 to 30 parts by weight, preferably 1 to
By adding so as to be in the range of 20 parts by weight, the immobilization effect is improved. The addition of these agents reduces the amount of heat-treated material that is the main substance of the immobilization material,
Not only can the volume of the solidified body generated in the immobilization treatment be reduced, but also the immobilization ability is much higher than when each is used alone for the immobilization treatment, and the elution standard value can be easily satisfied. Heat treated material 2 for 100 parts by weight of the object to be fixed
Assuming that 0 parts by weight are added (see Table 1 described later), the mixing ratio of the heat-treated product and the inorganic acid salt of iron in the harmful substance fixing material of the present invention is preferably 20: 5 to 30, and is preferably 20: 5 to 30. Is 2
The mixing ratio of the heat-treated product to the alkali metal or alkaline earth metal sulfide or hydrosulfide or thiourea is 20: 0.5 to 2, preferably 1 to 2.

Next, the immobilizing function of the material for immobilizing harmful substances will be described.
explain about. Calcium sulfoaluminate hydrate
Ettringite is ｛Ca₃[Al (OH)₆] ・
12H₂O｝³⁺Skeleton whose columnar structure extends in the C-axis direction
Are formed, during which SO₄Contains tetrahedrons and water molecules
It has an embedded crystal structure. Keep a large amount of water of crystallization
In the crystallization, the ion is located at the position of the Al atom.
Ti, Cr, Pb, Cd, Mn, Fe
It is known to easily replace metal ions. Also
｛Ca₃[Al (OH)₆] ・ 12H₂O｝³⁺Pillar shape
SO interposed between structures₄ ^2-The ions are also CrO₄ ^2-,
Cr₂O₇ ^2-, AsO₃ ^3-, AsO ₄ ^3-, SeO
₃ ^2-, Cl⁻, F⁻, NO₃ ⁻, NO₂ ⁻, CO₃
^2-, PO ₄ ^3-It is also possible to substitute
You. On the other hand, monosulfate is also [Ca₂Al (OH)
₆・ 2H₂O]⁺With a layered structure of
Heavy metal ions with similar ionic radii can be
Is the same as for ettringite, but in the skeletal structure
OH⁻+ 2H₂Since there is a vacancy of O, OH
⁻, AsO₃ ^3-, AsO₄ ^3-, Cl⁻, S
O₄ ^2-, PO₄ ^3-, NO₂ ⁻Is taken in.

The mechanism of immobilizing harmful substances of calcium sulfoaluminate hydrate is that harmful substances are contained in a hydrated state because the harmful substances are replaced and solid-solved in the crystal lattice, particularly when crystals are formed and grown. The immobilization ability can hardly be expected even if it is added to waste that is generated. In the present invention, the crystal lattice of calcium sulphoaluminate hydrate formed by heat-treating the hydrate to make the crystal structure amorphous once and contacting it with a harmful substance during the rehydration reaction It effectively substitutes and dissolves harmful substances into it. Therefore, the harmful substance is not simply adsorbed or physically fixed, so that the harmful substance can be more firmly fixed than a physical adsorbing and fixing agent such as cement. In addition, calcium sulfoaluminate hydrate
It is known that it has extremely low solubility, is inorganic, and stably exists over a long period of time, and is therefore excellent in the durability and durability of immobilizing harmful substances.

Inorganic acid salts of iron (ferrous sulfate, ferrous chloride,
Ferric sulfate, ferric chloride)
It is thought to have a function as a reducing agent and a function to form a precipitate of iron hydroxide and at the same time insolubilize heavy metals in a form like co-precipitation. However, since these iron salts have the effect of decomposing the solidifying material by acidification and have a rapid setting action by anions, the iron salt should be added in an amount of 30 parts by weight or more with respect to 100 parts by weight of the object to be fixed. Is not preferred.

Alkali metal or alkaline earth metal sulfides or hydrosulfides, thioureas are mainly cadmium,
It has the function of converting heavy metals such as lead, mercury, and chromium into hardly soluble sulfide salts. However, these are used as a precipitant for harmful heavy metal ions in water, but the particles to be formed are often fine, and when not used in combination with the heat-treated product, there is a possibility that they will flow out with water. For this reason, it is difficult to prevent elution from solid waste, and the objects to be used are also limited.

The harmful substance fixing material of the present invention is obtained by using a heat-treated material and at least one of an inorganic acid salt of iron, a sulfide or hydrosulfide of an alkali metal or an alkaline earth metal, and thiourea in combination. As a result, more powerful heavy metals can be immobilized, taking advantage of their characteristics and reinforcing their weak points.
It exerts various effects such as volume reduction of solidified material and application to a wide range of waste.

[0018]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, specific examples and effects of the fixing material of the present invention will be described with reference to examples, but the present invention is not limited to the following examples.

570 parts by weight of calcium hydroxide (special grade reagent), 430 parts by weight of anhydrous aluminum sulfate (special grade reagent), and 4000 parts by weight of distilled water are weighed in a stainless steel container and mixed for 5 hours while heating to 50 ° C. or higher. Stirring was allowed to proceed. After further aging at room temperature for 24 hours, after completion of the reaction, the solid phase was filtered and dried at 50 ° C.
Parts by weight were obtained. As a result of identifying a crystal phase by powder X-ray diffraction, the obtained solid was “ettringite”. Next, the obtained solid content was subjected to a heat treatment at 500 ° C. for 3 hours using an electric furnace to obtain 1000 parts by weight of a heat-treated product “A”.

460 parts by weight of calcium hydroxide (special grade reagent), 320 parts by weight of aluminum hydroxide (special grade reagent), 340 parts by weight of calcium sulfate dihydrate (special grade reagent) and 4000 parts by weight of distilled water are weighed in a stainless steel container. , 50 ° C
The mixture was stirred for 5 hours while heating as described above, and the reaction was allowed to proceed. After further aging at room temperature for 24 hours, after completion of the reaction, the solid phase was filtered and dried at 50 ° C. to obtain 1,260 parts by weight of a solid content. As a result of identifying the crystal phase by powder X-ray diffraction, the obtained solid was “monosulfate”. Next, the obtained solid content was subjected to a heat treatment at 500 ° C. for 3 hours using an electric furnace to obtain 1000 parts by weight of a heat-treated product “B”.

[0021]

Comparative Example 1 For 100 parts by weight of fly ash (garbage incinerator fly ash) having a Pb elution amount shown in Table 1, "A" was 10, and
After adding 20, 50, 100, 200 parts by weight and an appropriate amount of water and kneading the mixture, curing the mixture at room temperature for 5 days, pulverizing the fixed product after curing in a mortar, and adjusting the particle size to 0.5 to 5 mm. A dissolution test was performed based on the Environment Agency Notification No. 13. The extract was subjected to quantitative analysis of eluted components based on JIS K0102, and the results are shown in Table 1. As a result, the amount of Pb eluted was reduced, but the amount of Pb eluted was reduced to the landfill standard (0.3 mg / L) unless it was added in an equivalent amount or more to the object.
I couldn't go below. In Table 1 and subsequent tables, "ND"
Means below the detection limit.

[0022]

Comparative Example 2 For 100 parts by weight of fly ash shown in Table 1,
10, 20, 50, 100, 200 parts by weight of "B" and an appropriate amount of water were added and kneaded, and the same test as in Comparative Example 1 was conducted. As a result (Table 1), as in "A", the Pb elution amount could not be reduced below the landfill standard unless it was added in an amount equal to or greater than the target.

[0023]

Comparative Example 3 For 100 parts by weight of fly ash shown in Table 1,
10, 20, 50, 100, 20 of ordinary cement "C"
An appropriate amount of 0 parts by weight and water were added and kneaded, and a test was performed in the same manner as in Comparative Example 1. As a result (Table 1), the Pb elution amount was reduced, but did not satisfy the landfill standard.

[0024]

Comparative Example 4 With respect to 100 parts by weight of fly ash shown in Table 1,
Ferrous sulfate (FeSO ₄ ) was added to 5,10,15,20,3
An appropriate amount of 0 parts by weight and water were added and kneaded, and a test was performed in the same manner as in Comparative Example 1. As a result (Table 1), the elution amount of Pb was reduced but did not satisfy the landfill standard, and the elution amount tended to increase again when the added amount became 30 parts by weight. If the amount of ferrous sulfate added is 10 parts by weight or more,
The immobilized product becomes mud or slurry,
It was difficult to immobilize ferrous sulfate alone.

[0025]

Comparative Example 5 For 100 parts by weight of fly ash shown in Table 1,
Sodium sulfide (Na ₂ S) is 0.5, 1, _{2, 3, 5}
An appropriate amount of water and water were added and kneaded, and a test was conducted in the same manner as in Comparative Example 1. As a result (Table 1), the amount of Pb eluted was reduced, but did not satisfy the landfill standard.
At more than parts by weight, the elution amount did not change. This is considered to be due to the reaction product flowing out in the dissolution test using only sodium sulfide.

[0026]

Example 1 With respect to 100 parts by weight of fly ash shown in Table 1,
20 parts by weight of "A" and 5,10,20,3 ferrous sulfate
An appropriate amount of 0 parts by weight and water were added and kneaded, and a test was performed in the same manner as in Comparative Example 1. As a result (Table 1), the elution amount of Pb was reduced, and by adding 10 parts by weight or more of ferrous sulfate to 20 parts by weight of "A", the elution amount was below the landfill standard. The addition amount was smaller than when "A" or ferrous sulfate was used alone, and a high elution prevention effect was obtained.

[0027]

Example 2 For 100 parts by weight of fly ash shown in Table 1,
20 parts by weight of "B" and 5,10,20,3 ferrous sulfate
An appropriate amount of 0 parts by weight and water were added and kneaded, and a test was performed in the same manner as in Comparative Example 1. As a result (Table 1), the elution amount of Pb was reduced as in Example 1, and the elution amount was below the landfill standard by adding 10 parts by weight or more of ferrous sulfate to 20 parts by weight of "B". .

[0028]

Comparative Example 6 For 100 parts by weight of fly ash shown in Table 1,
20 parts by weight of "C" and 5,10,20,3 of ferrous sulfate
An appropriate amount of 0 parts by weight and water were added and kneaded, and a test was performed in the same manner as in Comparative Example 1. As a result (Table 1), the amount of Pb eluted was reduced as compared with the case where "C" was used alone, but did not satisfy the landfill standard.

[0029]

Embodiment 3 For 100 parts by weight of fly ash shown in Table 1,
20 parts by weight of “A” and 0.5, 1,
1.5, 3 parts by weight and an appropriate amount of water were added and kneaded, and a test was conducted in the same manner as in Comparative Example 1. As a result, the amount of Pb eluted was reduced, and by adding 1.5 parts by weight or more of sodium sulfide to 20 parts by weight of "A", the amount of eluted was below the landfill standard. The addition amount was smaller than when "A" or sodium sulfide was used alone, and a high elution prevention effect was obtained.

[0030]

Comparative Example 7 For 100 parts by weight of fly ash shown in Table 1,
20 parts by weight of “C” and 0.5, 1,
1.5, 3 parts by weight and an appropriate amount of water were added and kneaded, and a test was conducted in the same manner as in Comparative Example 1. As a result, the Pb elution amount was reduced as compared with the case where “C” was used alone, but did not satisfy the landfill standard.

[0031]

Example 4 For 100 parts by weight of fly ash shown in Table 1,
20 parts by weight of "A", 5 parts by weight of ferrous sulfate, 1 part by weight of sodium sulfide and an appropriate amount of water were added and kneaded. The test was carried out in the same manner as in Comparative Example 1. As a result (Table 1), Pb
The elution amount was below the detection limit. In addition, a very effective effect can be obtained with a smaller amount than when these fixing materials are used alone or when “A” is added with either ferrous sulfate or sodium sulfide. Obtained.

[0032]

Comparative Example 8 For 100 parts by weight of fly ash shown in Table 1,
20 parts by weight of "C", 5 parts by weight of ferrous sulfate, 1 part by weight of sodium sulfide and an appropriate amount of water were added and kneaded, and the same test as in Comparative Example 1 was conducted. As a result (Table 1), a higher effect can be obtained than when these immobilizing materials were immobilized by themselves or by adding either ferrous sulfate or sodium sulfide to "C". However, they did not meet the landfill standards.

[0033]

[Table 1]

[0034]

Comparative Example 9 "A" was 20, 50, 1 with respect to 100 parts by weight of the crust (glass melting furnace flue cleaning residue) in which the heavy metal content and the plurality of heavy metals eluted simultaneously as described in Table 2 were eluted.
An appropriate amount of 00 parts by weight and water were added and kneaded.
The test was performed in the same manner as in the above. The test results are shown in Table 2. C
Although the elution amounts of d, Pb, Cr ⁶⁺ , As, and Se were reduced, a large amount of “A” had to be added in order to reach the landfill standard.

[0035]

Comparative Example 10 To 100 parts by weight of the cinder shown in Table 2, 20, 50 and 100 parts by weight of "B" and an appropriate amount of water were added and kneaded, and the same test as in Comparative Example 1 was conducted. As a result (Table 2), a large amount of "B" had to be added to make the elution amount below the landfill standard.

[0036]

Comparative Example 11 To 100 parts by weight of the cinder shown in Table 2, 20, 50 and 100 parts by weight of "C" and an appropriate amount of water were added and kneaded, and the same test as in Comparative Example 1 was conducted. As a result (Table 2), the elution amount was reduced, but did not satisfy the landfill standard. Further, it is considered that Pb reacted with an alkaline component contained in “C” to form a soluble salt,
The elution volume increased.

[0037]

Example 5 20 parts by weight of "A" and 5, 10, 15 ferrous sulfate were added to 100 parts by weight of the cinder shown in Table 2.
An appropriate amount of water and water were added and kneaded, and a test was conducted in the same manner as in Comparative Example 1. As a result (Table 2), the elution amount of heavy metals decreased, and when 10 parts by weight or more of ferrous sulfate was added to 20 parts by weight of "A", the elution amount of all analyzed heavy metals was below the landfill standard. became. In addition, the addition amount was smaller than when "A" was used alone, and a high elution prevention effect was obtained.

[0038]

EXAMPLE 6 20 parts by weight of "B" and 5, 10, 15 ferrous sulfate were added to 100 parts by weight of the cinder shown in Table 2.
An appropriate amount of water and water were added and kneaded, and a test was conducted in the same manner as in Comparative Example 1. As a result (Table 2), the elution amount of heavy metals was reduced as in Example 5, and by adding 10 parts by weight or more of ferrous sulfate to 20 parts by weight of "B", all the heavy metals analyzed were reduced. The elution amount was below the landfill standard.

[0039]

Comparative Example 12 To 100 parts by weight of the cinder shown in Table 2, 20 parts by weight of "C", 15 parts by weight of ferrous sulfate and an appropriate amount of water were added and kneaded. The test was performed. As a result (Table 2), the elution amount of heavy metals was reduced, but the elution amount of Pb was able to be reduced by the effect of adding ferrous sulfate. Other heavy metals did not meet the landfill standards.

[0040]

Example 7 20 parts by weight of "A" and 100 parts by weight of cinder shown in Table 2
H), 0.5, 1, 2 parts by weight and an appropriate amount of water were added and kneaded, and the same test as in Comparative Example 1 was conducted. As a result (Table 2), the elution amount of heavy metals was reduced, and the same effect as when a large amount of "A" was used was obtained with a small amount of addition.

[0041]

Example 8 20 parts by weight of "B", 2 parts by weight of sodium hydrosulfide and an appropriate amount of water were added to 100 parts by weight of the cinder shown in Table 2 and kneaded, followed by the same test as in Comparative Example 1. Was done. As a result (Table 2), the elution amount of heavy metals was reduced as in Example 7.

[0042]

Comparative Example 13 20 parts by weight of "C", 2 parts by weight of sodium hydrosulfide and an appropriate amount of water were added to 100 parts by weight of the cinder shown in Table 2, and kneaded. Was done. As a result (Table 2), although the elution amount of heavy metals was reduced, the elution amount of Pb was not satisfied with the landfill standard although the elution amount of Pb was reduced by the effect of adding sodium hydrosulfide.

[0043]

EXAMPLE 9 20 parts by weight of "A", 10 parts by weight of ferrous sulfate, 1 part by weight of sodium hydrosulfide and an appropriate amount of water were added to 100 parts by weight of the cinder shown in Table 2 and kneaded. A test was conducted in the same manner as in Comparative Example 1. As a result (Table 2), the elution amounts of all analyzed heavy metals were below the detection limit. And "A" or "A" is ferrous sulfate,
A very effective effect was obtained with a smaller amount of use than when either of sodium hydrosulfide was used.

[0044]

Comparative Example 14 To 100 parts by weight of the cinder shown in Table 2, 20 parts by weight of "C", 10 parts by weight of ferrous sulfate, 1 part by weight of sodium hydrosulfide and an appropriate amount of water were added and kneaded. A test was conducted in the same manner as in Comparative Example 1. As a result (Table 2), a higher effect was obtained than when either ferrous sulfate or sodium hydrosulfide was added and immobilized to "C" or "C", but the landfill standard was satisfied. Did not reach.

[0045]

[Table 2]

[0046]

Comparative Example 15 20,100 parts by weight of "A" and an appropriate amount of water were added to 100 parts by weight of a waste fluorescent lamp (glass waste) showing the amount of total mercury (T-Hg) eluted as shown in Table 3. Then, the same test as in Comparative Example 1 was performed. The test results are shown in Table 3. Although the elution amount was reduced, even if the added amount of “A” was increased, the landfill standard was not satisfied.

[0047]

Comparative Example 16 To 100 parts by weight of the waste fluorescent lamp shown in Table 3, 20,100 parts by weight of "B" and an appropriate amount of water were added and kneaded, and the same test as in Comparative Example 1 was conducted. As a result (Table 3), the elution amount was reduced as in Comparative Example 15, but
Increasing the amount did not meet the landfill standards.

[0048]

Comparative Example 17 20,100 parts by weight of "C" and an appropriate amount of water were added to 100 parts by weight of the waste fluorescent lamp shown in Table 3 and kneaded, and a test was conducted in the same manner as in Comparative Example 1. (Table 3), the elution amount was hardly reduced.

[0049]

Example 10 20 parts by weight of "A", 1 part by weight of sodium sulfide and an appropriate amount of water were added to 100 parts by weight of the waste fluorescent lamp shown in Table 3 and kneaded. The test was performed. As a result (Table 3), the amount of T-Hg eluted was reduced to be below the landfill standard.

[0050]

Example 11 20 parts by weight of "B", 1 part by weight of sodium sulfide, and an appropriate amount of water were added to 100 parts by weight of the waste fluorescent lamp shown in Table 3 and kneaded. The test was performed. As a result (Table 3), the elution amount was lower than the landfill standard as in Example 10.

[0051]

Comparative Example 18 To 100 parts by weight of the waste fluorescent lamp shown in Table 3, 20 parts by weight of "C", 1 part by weight of sodium sulfide and an appropriate amount of water were added and kneaded. The test was performed. As a result (Table 3), the amount of T-Hg eluted was reduced by adding sodium sulfide, but did not satisfy the landfill standard.

[0052]

Example 12 20 parts by weight of "A", 1 part by weight of thiourea and an appropriate amount of water were added to 100 parts by weight of the waste fluorescent lamp shown in Table 3 and kneaded. The test was performed. As a result (Table 3), the elution amount of T-Hg was a value satisfying the landfill standard with a smaller amount of addition than when "A" was used alone.

[0053]

Comparative Example 19 To 100 parts by weight of the waste fluorescent lamp shown in Table 3, 20 parts by weight of "C", 1 part by weight of thiourea and an appropriate amount of water were added and kneaded. The test was performed. As a result (Table 3), the addition of thiourea reduced the elution amount of T-Hg, but did not meet the landfill criteria.

[0054]

Embodiment 13 To 100 parts by weight of the waste fluorescent lamp shown in Table 3, 20 parts by weight of "A", 5 parts by weight of ferrous sulfate, 1 part by weight of sodium sulfide and an appropriate amount of water were added and kneaded. And
The test was performed in the same manner as in Comparative Example 1. As a result (Table 3), the elution amount of T-Hg was below the detection limit.

[0055]

Comparative Example 20 To 100 parts by weight of the waste fluorescent lamp shown in Table 3, 20 parts by weight of "C", 5 parts by weight of ferrous sulfate, 1 part by weight of sodium sulfide and an appropriate amount of water were added and kneaded. And
The test was performed in the same manner as in Comparative Example 1. As a result (Table 3), the combined use of ferrous sulfate and sodium sulfide resulted in an elution amount below the landfill standard.

[0056]

[Table 3]

[0057]

Comparative Example 21 "A" was 50 and 100 parts by weight of the sludge showing the Pb elution amount and Pb content shown in Table 4.
After 100 parts by weight and an appropriate amount of water were added and kneaded, the mixture was cured at room temperature for 5 days, and the same test as in Comparative Example 1 was conducted. As a result (Table 4), the amount of Pb eluted could be reduced, but a large amount of "A" had to be added to satisfy the landfill standard.

[0058]

Comparative Example 22 To 100 parts by weight of the sludge shown in Table 4, 50 and 100 parts by weight of "C" and an appropriate amount of water were added and kneaded, followed by curing at room temperature for 5 days. The test was performed. As a result (Table 4), the amount of Pb eluted increased as the amount of “C” added increased. This is presumably because free calcium hydroxide contained in "C" and Pb in the sludge reacted to form a readily soluble compound.

[0059]

EXAMPLE 14 50 parts by weight of "A" and 5 parts of ferric chloride (FeCl ₃ ) were added to 100 parts by weight of sludge shown in Table 4.
After adding an appropriate amount of water and a suitable amount of water and kneading, the mixture was cured at room temperature for 5 days, and the same test as in Comparative Example 1 was performed. As a result (Table 4), a higher elution prevention effect was obtained than when "A" was immobilized at 100 parts by weight, and the elution amount of Pb was below the landfill standard.

[0060]

Comparative Example 23 To 100 parts by weight of the sludge shown in Table 4, 50 parts by weight of "C", 5 parts by weight of ferric chloride and an appropriate amount of water were added and kneaded, and the mixture was cured at room temperature for 5 days. The test was performed in the same manner as in Comparative Example 1. As a result (Table 4), "C"
When ferric chloride was added, the elution amount of Pb hardly changed, and the elution was only slightly prevented.

[0061]

[Table 4]

[0062]

Industrial Applicability By adding the product of the present invention to waste or wastewater containing harmful substances, the elution of harmful substances can be significantly reduced as compared with the conventional fixation treatment using cement or asphalt. The significance is significant.

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) // A62D 3/00 B09B 3/00 304J (72) Inventor Tsukasa Kamei 2120-4 Ogami, Hiratsuka-shi, Kanagawa 72) Inventor Teruo Urano 775-3 Ishizuka-cho, Sano City, Tochigi Prefecture (72) Inventor Kosuke Mori, 968 Papillon Sano C207 Furuhara-cho, Sano City, Tochigi Prefecture F-term (reference) 2E191 BA02 BB01 BD01 4D004 AA18 AA22 AA36 AA37 AA41 CA15 CA34 CA45 CC03 CC06 CC11 CC15 DA03 DA10 4D059 AA11 BG00 BJ00 DA01 DA02 DA03 DA15 DA23 DA24 DA31 DA34 DA70 DB21 DB40

Claims (1)

[Claims] 1. A rehydratable substance obtained by heat treatment of calcium sulfoaluminate hydrate, an inorganic acid salt of iron, a sulfide or hydrosulfide of an alkali metal or an alkaline earth metal, and thiourea. A material for immobilizing harmful substances, which is a mixture with at least one of the following.