JP2003024914A - Method for solidifying incinerated ash and fly ash with pressurized fluidized bed coal ash and method for using solidified body - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for solidifying an incineration ash and a fly ash originating from an industrial waste and a general waste by which a solid material which is of high strength and free from the elution of a heavy metal ion, is obtained. SOLUTION: This method for solidifying the incineration ash and the fly ash with the addition of coal cinders comprises the steps to add the combustion coal cinders of the pressurized fluid bed and an appropriate amount of water and knead these materials and further perform the solidification process of the mixture. The descriptions of the invension claim 2 cover the solidification process to add the combustion coal cinders of the pressurized fluid bed, cement and at least one selected from sodium carbonate, a polyaluminum chloride, aluminum sulfate and ferrous sulfate to the incineration ash and the fly ash of refuse and knead these materials, further with the addition of water.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to municipal waste incineration ash,
The present invention relates to a method for solidifying wastes such as fly ash and melting furnace fly ash, and a method for using the obtained solidified body.

[0002]

2. Description of the Related Art Incinerator ash and fly ash generated when incinerating municipal solid waste and industrial waste contain heavy metals such as Pb and Cd and cannot be directly landfilled. These incinerated ash and fly ash are specially controlled general waste,
Intermediate treatment by any of melt solidification, cement solidification, drug (chelate) treatment, and solvent extraction is obligatory. However, for example, in the case of chemical treatment, expensive chelating agent requires several% (by weight) with respect to the ash to be treated. Further, when the melting and solidifying process is performed, a large amount of equipment cost and a large amount of energy for melting and solidifying are required.
Thus, these intermediate treatments cause an increase in waste treatment cost.

Therefore, most of wastes such as incinerated ash, fly ash, and melting furnace fly ash are solidified by using a solidifying agent mainly composed of cement, and are landfilled.

[0004]

However, the strength of the solidified body is relatively low when the waste solidification method such as municipal solid waste incineration ash, fly ash, melting furnace fly ash and the like which uses a solidifying agent mainly composed of cement is used. Further, when left for a long period of time, there is a possibility that heavy metal ions and the like may be eluted. Thus, there is a problem that it is difficult to utilize the solidified body treated by the conventional technique as a roadbed material or a backfill material.

The present invention provides a waste solidification method capable of obtaining a solidified product having high strength and free of elution of heavy metal ions, and until now, it has been costly to dispose of it as industrial waste. An object of the present invention is to provide a method for solidifying wastes such as municipal waste incineration ash, fly ash, and melting furnace fly ash that can use coal ash generated from a coal-fired power plant as a solidifying agent.

[0006]

The invention according to claim 1 for solving the above-mentioned problems is to knead refuse incineration ash and fly ash by adding pressurized fluidized bed coal ash and an appropriate amount of water, and kneading. Incinerated ash by pressurized fluidized bed coal ash, which is characterized by performing solidification treatment,
It is a method of solidifying fly ash.

According to the second aspect of the present invention, incineration ash, fly ash, pressurized fluidized bed coal ash and cement, and one or more of sodium carbonate, polyaluminum chloride, aluminum sulfate and ferrous sulfate are used. A method for solidifying incineration ash and fly ash by pressurized fluidized bed coal ash, which further comprises adding an appropriate amount of water, kneading, and solidifying the mixture.

According to the third aspect of the invention, the content (weight) of the incinerated ash and fly ash is as follows: pressurized fluidized bed coal ash: 5% to
10%, cement: 0% to 5%, sodium carbonate: 1.
0% to 1.5%, polyaluminum chloride: 0% to 0.5
%, Aluminum sulfate 0% to 0.5%, ferrous sulfate: 0
% To 0.5% of 1 or 2 or more, and an appropriate amount of water is further added and kneaded to perform solidification treatment, which is a method for solidifying incineration ash and fly ash by pressurized fluidized bed coal ash. is there.

The invention according to claim 4 uses the solidified body obtained by the method for solidifying incinerated ash or fly ash according to any one of claims 1 to 3 as a roadbed material or a backfill material. It is a method of using incinerated ash and fly ash solidified material.

[0010]

The present invention has a high strength because of the above constitution.
It is possible to obtain a solidified product of wastes such as municipal waste incineration ash, fly ash, and melting furnace fly ash without elution of heavy metal ions. Also,
Up to now, coal ash generated from a coal-fired power plant, which has been costly to dispose of as industrial waste, can be used as a solidifying agent. In the present invention, coal ash from a pressurized fluidized bed combustion type coal-fired power plant is used. Pressurized fluidized bed combustion type coal-fired power plants have low NO _X , low SO _X and can utilize gas turbine power generation from exhaust gas from boilers, and their power generation efficiency is very high. To be The coal ash from this coal-fired power plant is not only used as an additive for secondary concrete products,
It can be used as a solidifying agent for incinerated ash and fly ash of industrial waste and general waste.

[0011]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention will be described below with reference to its preferred embodiments. In the present invention, the solidification treatment refers to waste such as municipal waste incineration ash, fly ash, and melting furnace fly ash.
Pressurized fluidized bed coal ash and cement as required, an appropriate amount of water is added and kneaded, and press molding, production, granulation, and other treatments are performed to form a lump.

[0012]

[Examples] Fly ash generated from a continuous stalker type combustion furnace in City A and fly ash collected when the incinerated ash generated in a continuous stalker type combustion furnace in City B was treated in an electric furnace type melting furnace,
40 kg each of fly ash collected in the direct melting furnace of C and C
It was collected. These fly ash were in a dry state in which lime milk or lime powder was sprayed on the flue and then dust was collected by a bag filter.

The fly ash was dried for about 24 hours in a constant temperature dryer kept at 105 ° C to 110 ° C to obtain a measurement sample.
The chemical analysis of these samples was carried out by powder X-ray diffraction on the contained minerals by the method specified in JIS R5202.
In addition, the elution test was carried out in accordance with the Environmental Agency Notification No. 3B and the availability test (NEN 7345 in the Netherlands).
Atomic absorption spectrometer 8 Japan Jarrell Ash Co., Flame atomic absorption, AA-880 Mar
k2). Elemental analysis of the solidified body obtained by the method for solidifying incinerated ash and fly ash of the present invention was carried out by a scanning electron microscope (SEM), EPMA and the like.

Among the samples, those which elute anions (Cr ⁶⁺ , As, etc.) are phosphoric acid (H ₃ PO ₄ ), ordinary cement, and pressurized fluidized bed combustion type coal in combination with ferrous sulfate. The dust collected from the thermal power plant, etc.
A predetermined amount was put into a mortar kneading bowl specified by 5201, mixed with a kneading rod, and a predetermined amount of each chemical was dissolved in kneading water and added to the mixture, and the mixture was kneaded by adding ion-exchanged water. Put the kneaded product in a plastic bag to harden it, and after about 24 hours, remove it from the plastic bag and store it in a thermostatic chamber (20 ° C ± 20 ° C).
After curing at 1 ° C. and humidity (RH): 80% ± 1% for 48 hours, it was cured naturally. Table 1 shows the chemical analysis values of coal ash generated from the commercial Portland cement used and the coal-fired power plant of the pressurized fluidized bed combustion system, the minerals contained, etc.
Shown in. Furthermore, the powder X-ray diffraction diagram and the measurement conditions are shown in FIG.
Shown in. For chemicals, use commercially available special grade reagents, kneading water,
Commercially available ion-exchanged water was used as the elution water.

[0015]

[Table 1]

After the lapse of a predetermined period (7 days, 28 days), the solidified body is crushed by a jaw crusher, and the temperature is 105 ° C to 110 ° C.
It was dried for about 48 hours in a constant temperature dryer kept at ° C, and used as a dissolution test sample according to the method announced by the Environment Agency and also as a powder X-ray diffraction measurement sample.

For the combustion method of coal in a coal-fired power plant
Is pulverized coal combustion system, fluidized bed combustion system, pressurized fluidized bed combustion
There is a method. Stones produced by pulverized coal combustion method or fluidized bed combustion method
For coal ash, cement should be distributed unless a small amount of lime or gypsum is added.
Even if combined, the curing strength is low. In contrast, pressurized fluidized bed combustion
In the combustion process, coal ash is mixed with limestone in the combustion process.
It burns in the state of being burned, and the sulfur contained in the coal is oxidized and raw.
Ji SO_TwoAnd limestone (CaCO_Three) Reacts and plaster (C
aSO_Four) Is produced and contained,
It also shows a considerable hardening strength in taste and uses a little cement in combination.
It cures very well. Stone by pressurized fluidized bed combustion method
In the charcoal combustion process, coal and limestone are mixed and burned in the formation.
By doing so, an in-furnace desulfurization reaction occurs. That is, CaCO_Three→ CaO + CO_Two S + O_Two→ SO_Two CaO + SO_Two+ 1 / 2O_Two→ CaSO_Four Also, under pressure, CaCO_Three+ SO_Two+ 1 / 2O_Two→ CaSO_Four The direct reaction of limestone to promote desulfurization
Plaster with ash (CaSO _Four) Is generated.

These pulverized coal combustion systems, fluidized bed combustion systems,
In order to compare the coal ash of each of the pressurized fluidized bed combustion method and the pressurized fluidized bed combustion method, each sample having a mixing ratio shown in Table 5 is a mold (mold: 10 cmφ ×) specified in JIS for each sample.
(12.7 cm length) divided into 3 layers, each layer dropped the rammer 25 times, demolded with a stuffing sleeve, cured for 12 days in moisture and cured for 1 day in water to give concrete uniaxial compressive strength. It was measured (n = 3). The results are shown in Table 7.

[0019]

[Table 5]

[0020]

[Table 7]

Furthermore, after mixing the respective raw materials in the mixing ratio shown in Table 5, a pelletizer (50 cmφ × 10 cm) was used.
Granulation while sprinkling water at a depth of 18 rpm to 20 rpm), the pellets obtained were cured in a plastic bag, and after 7 days, taken out from the plastic bag and measured for crush strength (n
= 5). The results are shown in Table 7. The properties of the coal ash used in the comparative test are shown in Table 1-1.

[0022]

[Table 1-1]

When municipal incineration ash, fly ash, and melting furnace ash contain aluminum, when solidified by cement, hydrogen gas is generated in about 3 to 6 months,
The solidified body expands and collapses. In order to prevent the expansion and the disintegration, the metallic aluminum is treated with an alkaline solution or the like to be converted into aluminum hydroxide or the like, and then solidified with chemicals such as ferrous sulfate and polyaluminum chloride.

Fly ash generated in the municipal solid waste incinerator (continuous stalker type furnace), fly ash generated when the incinerator ash and fly ash are melted and solidified by an electric furnace, and the municipal solid waste are directly melted in the melting furnace. Table 2 shows the chemical analysis values of the fly ash generated during the treatment, and the fly ash when melted and solidified (water slag) in the melting furnace, and Table 3 shows the main contained minerals.

[0025]

[Table 2]

As is clear from Table 2, the chemical composition of the municipal solid waste incinerator fly ash and the melting furnace fly ash is Ig · Loss, SiO.
₂ , CaO, Na ₂ O, K ₂ O and Cl are the main components, and Cl,
Volatile substances such as Pb and Zn are concentrated in fly ash, especially in the melting furnace fly ash.

[0027]

[Table 3]

The above-mentioned coal ash sample was tested by the Environment Agency Notification 13
The elution test of heavy metal ions etc. was carried out by the No. B method and the availability method. The results are shown in Table 4.

[0029]

[Table 4]

As is clear from Table 4, Cl, Pb, Z
n, etc. elutes and exceeds the regulation value under the Environmental Agency Notification No. 13B Law. Further, the dissolution test results by the availability method greatly exceed the regulation value due to the pH of the dissolution solution being as low as 4. On the other hand, as shown in Table 3, contained minerals are Ca (OH) ₂ , NaCl, KCl, and CaC.
_{O 3, CaClOH, Ca (ClO} ) 2 · 4H 2 O, 2
Examples thereof include CaO / Al ₂ O ₃ / SiO ₂ .

In the present invention, the pressure fluidized bed combustion coal ash: 5% to 1 in terms of internal content (weight) with respect to refuse incineration ash and fly ash
0%, cement: 0% -5%, sodium carbonate: 1%-
1.5%, polyaluminum chloride: 0% to 0.5%, aluminum sulfate: 0% to 0.5%, ferrous sulfate: 0% to
It is added at a compounding ratio of 0.5%. This is for the reason explained below. If the blending ratio of the pressurized fluidized bed combustion coal ash, cement and chemicals is less than the lower limit, the additive effect cannot be exhibited. On the other hand, the upper limit is because the addition effect is saturated at this blending amount.

As shown in Table 1, the chemical components and main minerals contained in the pressurized fluidized bed combustion coal ash are CaSO ₄ , Si.
_{O2, Al 2 O 3, CaO} , SO 3 is in principal CaSO ₄
Is high in content. Then, when the pressurized fluidized bed combustion coal ash is mixed as it is or with cement and water is added and kneaded,
It has the property of solidifying very quickly.

On the other hand, as a method for reducing the solubility of Ca, Na, Cl or the like in water, sulfides are formed (sodium sulfide, ferrous sulfate, etc. are added), and acetyl salts are formed (dithiocarbamic acid, etc. are added). There is a method of forming a carbonate (addition of sodium carbonate, polyaluminum chloride, aluminum sulfate, etc.), a generation of a phosphate (addition of phosphoric acid (H ₃ PO ₄ )) and the like.

Therefore, pressurized fluidized bed combustion coal ash, cement and chemicals (chemicals are blended after being dissolved with ion exchange water) are mixed with incinerator fly ash and melting furnace fly ash, and the insufficient water is ion exchanged. Water was added and kneaded, and then solidified, the elapsed time after solidification was changed, and the elution test and the amounts of Ca, Na, Cl, SO ₄ ions, etc. in the eluted water were measured in accordance with the Environmental Agency Notification Method and the Availability Method. . The results are shown in Table 6-1 to Table 6-4.
Shown in.

[0035]

[Table 6-1]

[0036]

[Table 6-2]

[0037]

[Table 6-3]

[0038]

[Table 6-4]

In summary of the above results, a) Compared to the formation of sulfides, acetates and phosphates,
Considering the amount of goods used (cost including price), charcoal
Effective generation of acid salt and elution amount of Ca ion from solidification
Can also be reduced. Sodium carbonate is 0.5% to 1.5%
The effect can be obtained by adding a relatively small amount. b) Pressurized fluidized bed combustion coal ash is CaSO_FourContains a lot of
Kneading alone or compounding cement and adding water,
It solidifies very quickly and also contains Cr among heavy metals. ³⁺When
It is possible to prevent elution of such cations. Chemicals
If solidification treatment is performed by using⁶⁺Such as Yio
It is also possible to prevent the elution of ions. That is, the shadow in the fly ash
On (Cr⁶⁺Etc.) is ferrous sulfate.
It is effective to use them together for solidification. The eluted ions
The amount of chemicals added may increase or decrease depending on the amount. c) Ca, Na, K, Cl, SO in the elution solution_Fourion
Of these, C becomes a problem especially as a source of scale, C
a, SO_FourThe amount of ions eluted is determined by the solidification treatment of fly ash.
By adding 0.5% to 1.5% of sodium carbonate
Significantly reduced. However, for the elution of Cl ions
The reduction effect is small. Sodium carbonate is carbonated when dissolved in water.
Generates gas to produce carbonate, which dissolves heavy metal ions
Useful for prevention. That is, Ca²⁺+ NaCO_Three→ CaC
O_Three+ 2Na²⁺  Reaction occurs, Ca ion decreases
It seems to be less. d) Coal ash of the pressurized fluidized bed combustion system is pulverized coal combustion system or
Gypsum content is 25% more than fluidized bed combustion type coal ash
High as high as 27%, with high solidification strength without the addition of cement
Expresses. By adding a small amount of cement,
Further, the solidification strength is increased. Pressurized fluidized bed combustion type coal ash
Solidified by mixing and assembling municipal waste incinerator ash and fly ash, and melting furnace fly ash.
Therefore, the elution of heavy metal ions can be prevented, and the obtained solid
It is possible to use the fossilized material as a lower roadbed material, backfill material, etc.
Wear.

[0040]

According to the present invention, coal ash generated from a coal-fired power plant, which has been costly to dispose of as industrial waste, can be utilized as a roadbed material, a backfill material, etc. It is possible to obtain a solidified product such as municipal waste incineration ash, fly ash, and melting furnace fly ash that has high strength and does not elute heavy metal ions.

According to the inventions of claims 2 and 3, the elution of heavy metal ions can be prevented more reliably,
Solidified materials such as incineration ash and fly ash of industrial waste and general waste can be utilized as highly reliable lower roadbed materials and backfill materials.

According to the invention described in claim 4, solidified bodies such as incineration ash and fly ash of industrial waste and general waste can be effectively utilized.

[Brief description of drawings]

FIG. 1 is a graph showing a powder X-ray diffraction result of coal ash in a pressurized fluidized bed combustion system.

Claims (4)

[Claims] 1. An incineration ash, fly ash by a pressurized fluidized bed coal ash, characterized in that the incineration ash and fly ash are kneaded by adding pressurized fluidized bed coal ash and an appropriate amount of water and solidified. Ash solidification method. 2. Incinerator ash and fly ash are mixed with pressurized fluidized bed coal ash, cement and one or more of sodium carbonate, polyaluminum chloride, aluminum sulfate and ferrous sulfate, and an appropriate amount of water. A method for solidifying incineration ash and fly ash by pressurized fluidized bed coal ash, which is characterized by additionally kneading and solidifying. 3. Internal content (weight) for refuse incineration ash and fly ash
Then, pressurized fluidized bed coal ash: 5% to 10%, cement: 0%
~ 5%, sodium carbonate: 1.0% to 1.5%, polyaluminum chloride: 0% to 0.5%, aluminum sulfate 0
% -0.5%, ferrous sulfate: 1% or more of 0% -0.5%, and an appropriate amount of water is added and kneaded to perform solidification treatment. Solidification method of incineration ash and fly ash by floor coal ash. 4. An incineration ash and a fly ash solidified body, wherein the solidified body obtained by the solidification method of the incineration ash or fly ash according to any one of claims 1 to 3 is utilized as a roadbed material or a backfill material. How to use.