JP2001219134A - METHOD FOR DISPOSING OF HIGH pH SUBSTANCE - Google Patents

Abstract

PROBLEM TO BE SOLVED: To rapidly start the use of a land-fill site when a high pH substance represented by incineration ash is disposed of for land-fill measures. SOLUTION: IN the method for disposing of a high pH substance, first, a spread/level-off layer 3a is formed by spreading and levelling off the incineration ash 2 as the high pH substance on a protecting layer 1 formed on the bottom surface of a disposal site. Next, recessed parts 6 for dumping dry ice 7 are dug and formed in the previously formed spread/level-off layer 3a and then the dry ice 7 is dumped in the recessed parts 6. After that, the recessed parts 6 are blocked with the incineration ash 2 and, at the same time, a spread/ level-off layer 3b is formed anew by spreading/levelling off the incineration ash 2 on the previously formed layer 3a as illustrated by Fig. (d). Thus, the described process is repeated in the rest so that the ash 2 is land-filled in such a state a that it is mixed with the dry ice 7 and the ash 2 is maintained in a constantly wet condition.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for treating high pH substances such as coal ash mainly generated from thermal power plants.

[0002]

2. Description of the Related Art Most of incinerated ash, such as coal ash generated from thermal power plants and ash generated after incineration of wastes, is mostly landfilled unless it can be recycled. In particular, when coal ash is landfilled at a waste disposal site, high-alkaline leaching water is generated with the infiltration of rainwater, and if left as it is, alkali components may flow into the groundwater system together with the rainwater.

[0003] Therefore, even after the landfill disposal is completed, leachate from coal ash is collected in a drainage structure laid on the bottom of the disposal site, and the pH of the leachate is adjusted to a predetermined drainage standard.
For example, the exuded water is pumped up until 5.8 to 8.6 is cleared, neutralized, and then discharged to prevent the exuded component from the landfill material from diffusing into the environment.

[0004]

However, the leaching of alkali from incinerated ash such as coal ash takes a long time, and the above-mentioned work also takes a long time. In addition to the cost of processing, the use of the landfill, which is a valuable land resource, is delayed or practically difficult.

[0005] Such a situation is caused not only by incineration ash, but also by high p-powder such as cement mixed soil, lime mixed soil and concrete waste.
A similar problem arises when landfilling H substances.

The present invention has been made in view of the above-mentioned circumstances, and has been developed in consideration of the above-mentioned circumstances. It is an object to provide a processing method.

[0007]

In order to achieve the above object, a method for treating a high pH substance according to the present invention comprises, as described in claim 1, incinerated ash, cement mixed soil, lime mixed soil,
When processing high pH substances such as concrete waste,
The above process is performed in a state where dry ice is mixed in the H substance, and thereafter the high pH mixed with the dry ice is used.
It keeps the material in a constant wet state.

In the method for treating a high pH substance according to the present invention, a concave portion for introducing dry ice is formed by excavation in the pre-formed leveling layer, and the dry ice is supplied to the concave portion for supplying dry ice. Thereafter, the step of laying the high pH substance on the laying layer previously formed and closing the dry ice charging recess with the high pH substance to form a new laying layer is repeatedly performed. Things.

Further, in the method for treating a high pH substance according to the present invention, the dry ice is disposed in a state covered with a heat insulating material on a previously formed spread layer, and then the high ice substance is disposed. Immediately before being covered with the above, the step of laying out the high pH substance on the previously formed spreading layer while removing the heat insulating material to form a new spreading layer is repeated.

Further, the method for treating a high-pH substance according to the present invention is to maintain the high-pH substance after the treatment or the spreading layer made of the high-pH substance in an airtight state.

Further, the method for treating a high pH substance according to the present invention is, as described in claim 5, in a landfill made of a high pH substance such as incineration ash, cement mixed soil, lime mixed soil, concrete waste and the like. After excavating a shaft in a landfill and then putting dry ice into the shaft, the shaft is kept airtight and the landfill is maintained in a constant wet state.

Further, in the method for treating a high pH substance according to the present invention, the lower end of the shaft is communicated with a water collecting pipe arranged at the bottom of the landfill, and carbon dioxide sublimated from the dry ice is supplied to the water collecting pipe. From the water collection hole.

In the method for treating a high pH substance according to the first aspect of the present invention, when treating a high pH substance, the treatment is performed in a state where dry ice is mixed in the high pH substance, and thereafter dry ice is mixed. The maintained high pH substance is maintained in a constant wet state.

For high pH substances, elution into water provides high p
Alkali metals and alkaline earth metals presenting H are included, but when a high pH substance is treated by the method described above, the eluted alkali component, for example, Ca ²⁺ is a solid of carbon dioxide. It reacts with carbon dioxide gas sublimated from dry ice to change to carbonate, and dissociation into water is suppressed to become neutral.

That is, Ca ²⁺ + 2OH ⁻ + CO ₂ → Ca
The chemical reaction of CO ₃ + H ₂ O proceeds, and the high pH substance changes to a neutral substance.

The high pH substance means a substance which exhibits alkalinity when it comes into contact with water, and specifically includes incinerated ash such as coal ash, cement mixed soil, lime mixed soil,
Concrete waste and the like are included.

The treatment of a high-pH substance means a treatment in all situations where alkali elution is a problem, and includes, for example, treatment of transportation, temporary storage, landfill, embankment and the like.

The constant wet state after mixing dry ice is
It is a condition for the above-mentioned chemical reaction to proceed, as long as such a chemical reaction proceeds, the degree of wetting is arbitrary, and whether the wet state is artificially created by means such as watering or natural action such as groundwater or rainfall It is also optional whether to use. On the other hand, if the high pH substance has a certain water content from the beginning, it may be unnecessary to newly add water. The wet state only needs to be maintained after mixing with dry ice, and it goes without saying that the wet state may be maintained before mixing with dry ice.

Various methods and timings can be selected for mixing dry ice with the high pH substance, for example, loading, temporary storage, landfill, and the like for transporting the high pH substance.
It may be mixed during the processing such as embankment, or may be dispersed on the surface of the high pH substance after the above-mentioned processing is completed, and then both may be stirred and mixed.

[0020] Here, a dry ice charging recess is formed by excavating the previously formed spread layer, and the dry ice is charged into the dry ice charging recess. In the case where the step of laying the high pH substance and forming a new laying layer on the laying layer formed in advance while closing with the pH substance is repeatedly performed, carbon dioxide sublimated from dry ice is used. It is possible to suppress the release of gas into the atmosphere and to ensure that the carbon dioxide gas permeates the spreading layer.

The form, such as the depth, shape, and arrangement of the concave portions for putting dry ice, is arbitrary, and a large number of hole-shaped ones are arranged in a line at equal pitches in two directions. A form such as disposing them in a lattice is conceivable.

Further, the dry ice is placed on the pre-formed spreading layer in a state covered with a heat insulating material,
Then, immediately before being covered with the high pH substance, the high p material is removed on the previously formed leveling layer while removing the heat insulating material.
The same applies to the case where the process of forming a new spreading layer by spreading the H substance is repeated.

The heat insulating material is preferably light and inexpensive and easy to peel off. For example, it is conceivable that the heat insulating material is made of a paper sheet.

In each of the above-mentioned inventions, when the high-pH substance or the spread layer made of the high-pH substance after each of the above-mentioned treatments is maintained in an airtight state, the release of carbon dioxide gas into the atmosphere is achieved. Can be more reliably prevented.

As a method for maintaining an airtight state, a high pH
Covering the air-exposed surface of the spreading layer made of the substance or the high-pH substance with an air-tight sheet made of vinyl, bentonite slurry, clay slurry, or the like, for a container having an airtight state or a low degree of contact with the atmosphere, for example, a concrete mixer truck. A method such as transporting the product in a loaded state is conceivable.

In the method for treating a high pH substance according to the invention of claim 5, a shaft is excavated in a landfill made of a high pH substance, and then dry ice is charged into the shaft, and then the shaft is hermetically sealed. And maintain the landfill at a constant wet condition.

For high pH substances, high p
Alkali metals and alkaline earth metals presenting H are included, but when a high pH substance is treated by the method described above, the main component of the eluted alkali, for example, Ca ²⁺ sublimes from dry ice. It reacts with carbon dioxide and changes to carbonate,
The dissociation into water is suppressed and becomes neutral.

That is, Ca ²⁺ + 2OH ⁻ + CO ₂ → Ca
The chemical reaction of CO ₃ + H ₂ O proceeds, and the landfill changes to neutral ground.

The high pH substance and the constant wet state are the same as those described with respect to the first aspect of the present invention.
Here, the description is omitted.

The depth and shape of the shaft are arbitrary. For example, it is conceivable to form a hole in a circular cross section with an earth auger or the like, or to excavate and form a groove with a backhoe or the like.

Here, when the landfill is a waste disposal site or the like, the lower end of the shaft is communicated with a water collection pipe arranged at the bottom of the landfill to remove carbon dioxide sublimated from the dry ice. By discharging from the water collecting hole of the water collecting pipe,
It is possible to expand the area of landfill where carbon dioxide gas permeates.

[0032]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the method for treating a high pH substance according to the present invention will be described below with reference to the accompanying drawings. It is to be noted that the same reference numerals are given to components and the like that are substantially the same as those in the conventional technology, and description thereof will be omitted.

(First Embodiment)

In the present embodiment, the method for treating high pH substances according to the present invention is applied to the incineration ash burial treatment at a waste disposal site, and FIG. 1 is a diagram showing a construction procedure at that time. is there. As shown in the figure, in the method for treating a high pH substance according to the present embodiment, first, as shown in FIG.
Incineration ash 2 as a high-pH substance is spread over a protective layer 1 made of sand or the like provided on the bottom of the disposal site, and spread over the layer 3a.
To form At the time of spreading, for example, using a bulldozer 4, spread the surface to, for example, several tens cm to about 1 m,
Roll as appropriate as needed. As the incineration ash 2, for example, coal ash can be cited as a typical example.

At the boundary between the disposal site and the surrounding ground,
Generally, a water-blocking sheet (not shown) for preventing water in the disposal site from leaking to the surroundings is provided, and the above-described protective layer 1 prevents the water-blocking sheet from being damaged. A drainage pipe 5 is laid in the protective layer so as to collect rainwater collected from the bottom of the disposal site and seepage water from waste.

Next, as shown in FIG. 3 (b), a concave portion 6 for introducing dry ice is formed by excavation in the spreading layer 3a formed in advance, and then dry ice 7 is introduced into the concave portion for introducing dry ice. I do.

Here, the size, shape, or amount of the dry ice 7 is adjusted so that the incineration ash 2 is efficiently neutralized, the alkalinity of the incinerated ash 2, the height of the spread layer 3 a, and the amount of the dry ice. The depth may be appropriately determined in consideration of the depth and the like of the concave portion 6, but the amount of the input may be, for example, 1 t of incineration ash.
It can be considered to be 10 to 50 kg per (dry mass). Further, the size of the dry ice 7 is desirably not a lump but a granular shape, for example, about several tens mm, so that no void remains in the incineration ash 2.

FIG. 2 is a view showing a plan arrangement of the concave portions 6 for introducing dry ice. As can be seen from FIG. 2, circular holes are arranged at equal intervals in two directions (FIG. 2A). Are arranged in a zigzag pattern ((b) in the figure), the groove-shaped holes (trench) are arranged in parallel ((c) in the figure), and the groove-shaped holes are arranged in a grid pattern (the same figure).
An arrangement such as (d)) is conceivable.

Next, as shown in FIG. 1 (c), the dry ice charging recess 6 is closed with the incineration ash 2 and, as shown in FIG. 1 (d), on the pre-formed spreading layer 3a. Incineration ash 2
To form a new spreading layer 3b. Or later,
By repeating the above steps, the incineration ash 2 is landfilled with the dry ice 7 mixed therein. The closing operation after the introduction of dry ice is performed as quickly as possible, and care is taken to minimize the loss due to the release of carbon dioxide into the atmosphere.

Next, in this state, the incineration ash 2 is maintained in a constant wet state.

In this manner, the alkaline components contained in the incineration ash 2, that is, Ca ²⁺ , which is an alkali metal or an alkaline earth metal which exhibits a high pH by being eluted in water, are not subjected to dry ice. It reacts with the carbon dioxide gas sublimated from 7 and changes to carbonate, and dissociation into water is suppressed to become neutral. That is,

Ca ²⁺ + 2OH ⁻ + CO ₂ → CaCO ₃ + H ₂ O

A chemical reaction proceeds, and the incineration ash 2 changes to a neutral substance.

The constant wet state after mixing the dry ice 7 is a condition for the above-mentioned chemical reaction to proceed. As long as such a chemical reaction proceeds, the degree of wetness is arbitrary. Regarding the timing of the incineration ash, for example, a method in which the water content of the incineration ash 2 is increased in advance by spraying water while spreading with the bulldozer 4 can be considered.

As described above, according to the method for treating a high pH substance according to the present embodiment, when landfilling the incinerated ash 2 which is a high pH substance, dry ice 7 is mixed into the incinerated ash 2. Since the incineration ash 2 mixed with the dry ice 7 was kept in a constant wet state after that, the Ca ²⁺ contained in the incineration ash 2 sublimated from the dry ice 7. Reacts with carbon dioxide and changes to carbonate.

Therefore, Ca contained in the incineration ash 2
The dissociation of ²⁺ into water is suppressed, and the incineration ash 2 can be immediately neutralized.

Further, according to the method for treating a high pH substance according to the present embodiment, the concave portion 6 for introducing dry ice is formed by excavation in the leveling layer 3a formed in advance, and the dry ice is formed in the concave portion for introducing dry ice. 7 and then, while closing the dry ice charging recess 6 with the incineration ash 2, lay the incineration ash 2 on the previously formed leveling layer 3a to form a new leveling layer 3b. Is performed repeatedly, so that the carbon dioxide sublimated from the dry ice 7 is prevented from being released into the atmosphere.
Can be reduced, and carbon dioxide gas can be surely permeated into the spread layers 3a, 3b,....

[0048] Therefore, it does not take a long time to neutralize the incinerated ash naturally, nor does it take a large amount of cost to neutralize the incinerated ash with chemicals. It is possible to start using landfill landfills, which are valuable land resources at low cost, at an early stage.

In addition, since dry ice emits only harmless carbon dioxide gas and has only a chemical reaction product of water and poorly soluble salts, it differs from neutralization with a chemical such as hydrochloric acid. The effect that mild persistence can be expected as long as dry ice is present without causing chemical problems, and heavy metals from incinerated ash due to a sudden drop in pH due to the use of chemicals such as hydrochloric acid There is also an operational effect that there is no need to worry about elution.

More specifically, if the gaseous carbon dioxide is handled directly, the only option is to fill the cylinder and supply it by piping. However, the former has a problem in weight during transportation, and the latter has a problem in initial cost of the supply equipment. Become. In that regard, according to the method for treating a high pH substance according to the present embodiment,
Since the incineration ash is neutralized using solid dry ice, there is also a remarkable effect that the handling is extremely easy regardless of the processing steps such as transportation and landfill.

Next, the effect of the method for treating a high pH substance according to the present embodiment has been confirmed by experiments, and the outline thereof will be described below.

First, incineration ash is filled in a column made of an acrylic cylinder to form an incineration ash layer, and a mixture of incineration ash and dry ice is filled thereon to form a mixed layer. After filling the incineration ash to form an incineration ash layer, it was cured for a certain period of time to secure a reaction time.

Next, distilled water was injected from above the column, and permeated water was collected in a container set below the column.
The pH and alkalinity of the permeated water (neutralization titration at pH 7 with 0.1 molar hydrochloric acid) were measured.

FIG. 3 shows the measurement results. The figure shows that the pH and alkalinity of the permeated water are significantly reduced by the addition of dry ice.

In this embodiment, the spreading layers 3a, 3b
In each case, the concave portion 6 for dry ice was formed by excavation. However, when the layer thickness of the spread layer is small, the concave portion 6 for dry ice is collectively excavated and formed by several layers. Is also good.

Although not particularly mentioned in the present embodiment, after the landfilling process is completed, of the spread layers 3a, 3b,... Each spread layer 3 by covering the upper surface with an airtight sheet
may be maintained in an airtight state.

According to this configuration, it is possible to further reduce the loss of carbon dioxide gas in the form of release to the atmosphere, and to further promote the neutralization of the incineration ash 2.

(Second Embodiment)

Next, a second embodiment will be described. Note that components that are substantially the same as those in the first embodiment are given the same reference numerals, and descriptions thereof are omitted.

In this embodiment, as in the first embodiment, the method for treating high-pH substances according to the present invention is applied to the burial of incineration ash at a waste disposal site. FIG. It is a figure showing a procedure. As shown in the figure, in the method for treating a high pH substance according to the present embodiment, first,
As shown in (a), dry ice 7 is placed on a protective layer 1 made of sand or the like provided on the bottom of a disposal site in a state covered with a heat insulating material. The heat insulating material is preferably made of a lightweight and inexpensive material that is easy to peel off, for example, a paper sheet.

Next, the incineration ash 2 which is a high pH substance is spread on the protective layer 1 on which the dry ice 7 is disposed. At this time, sublimation of carbon dioxide is prevented until the incineration ash 2 is covered. The dry ice 7 is covered with a heat insulating material in order to remove the heat insulating material immediately before the incineration ash 2 is covered, thereby exposing the dry ice 7 therein, as shown in FIG. The spread layer 3a is formed by spreading.

Next, as shown in FIG. 6C, dry ice 7 is placed on the previously formed spread layer 3a in the same manner as described above, and the heat insulating material is placed just before the incineration ash 2 is covered. Peeling off the incinerated ash 2 on the spread layer 3a while exposing the dry ice 7 inside, and forming a new spread layer 3b
To form Thereafter, by repeating the above-described steps, the incineration ash 2 is landfilled with the dry ice 7 mixed therein.

Next, in this state, the incineration ash 2 is maintained in a constant wet state.

Thus, the alkaline components contained in the incineration ash 2, that is, Ca ²⁺ , which is an alkali metal or alkaline earth metal which exhibits a high pH by being eluted in water, is reduced to the first concentration. As described in the embodiment, it reacts with carbon dioxide sublimated from the dry ice 7 to change into carbonate, and dissociation into water is suppressed to become neutral.

As described above, according to the method for treating a high pH substance according to the present embodiment, when landfilling the incinerated ash 2 which is a high pH substance, dry ice 7 is mixed into the incinerated ash 2. Since the incineration ash 2 mixed with the dry ice 7 is kept in a constant wet state after that, the Ca ²⁺ contained in the incineration ash 2 is the same as in the first embodiment. Dissociation into water is suppressed,
The incineration ash 2 can be immediately neutralized.

Further, according to the method for treating a high pH substance according to the present embodiment, dry ice 7 is placed on the previously formed leveling layer 3a, and carbon dioxide gas is insulated by the heat insulating material until immediately before the incineration ash 2 is covered. Since the process of laying incineration ash 2 on the preceding spread layer and forming a new spread layer while preventing sublimation was performed repeatedly, the carbon dioxide gas sublimated from the dry ice 7 was removed. Suppress the release into the atmosphere, in other words, reduce the loss that does not contribute to the neutralization of the incineration ash 2 and spread carbon dioxide gas on each of the layers 3a, 3b,.
It is possible to surely penetrate.

Therefore, it does not take a long time to naturally neutralize the incinerated ash and a large cost to neutralize the incinerated ash with a chemical. It is possible to start using landfill landfills, which are valuable land resources at low cost, at an early stage.

Also, since dry ice emits only harmless carbon dioxide gas and has only the chemical reaction products of water and hardly soluble salts, it differs from neutralization with a chemical such as hydrochloric acid. The effect that mild persistence can be expected as long as dry ice is present without causing chemical problems, and heavy metals from incinerated ash due to a sudden drop in pH due to the use of chemicals such as hydrochloric acid There is also an operational effect that there is no need to worry about elution.

Although not specifically mentioned in the present embodiment, after the landfill process is completed, each spread layer 3 made of incineration ash 2 is used.
a, 3b,..., the air-exposed surface, that is, the upper surface of the uppermost layer is covered with an airtight sheet, so that each spreading layer 3a, 3b
.. May be maintained in an airtight state.

According to this configuration, it is possible to further reduce the loss of carbon dioxide in the form of release to the atmosphere, and to further promote the neutralization of the incineration ash 2.

In this embodiment, a paper sheet is used as an example of a heat insulating material coated with dry ice 7 to prevent sublimation of carbon dioxide gas. Anything is fine,
For example, it is conceivable to cover the incineration ash 2 with a scoop or the like.

(Third Embodiment)

Next, a third embodiment will be described. Note that the same reference numerals are given to components and the like that are substantially the same as those of the first and second embodiments, and description thereof will be omitted.

In this embodiment, the method for treating high-pH substances according to the present invention is applied to a series of processes such as temporary placement, transportation and landfill of incinerated ash, and FIG. 5 shows a construction procedure at that time. FIG. As shown in the figure, in the method for treating a high pH substance according to the present embodiment, first,
As shown in (a), the spreading layers 3a, 3b, 3c... are sequentially laminated while mixing the dry ice 7 into the incineration ash 2. The procedure is the same as in the second embodiment, and a description thereof is omitted here. When the volume of the incineration ash 2 is small, as shown in FIG.
The incineration ash 2 may be temporarily placed so as to cover the dry ice 7 placed in advance in a mountain shape.

Next, after maintaining the incinerated ash 2 mixed with the dry ice 7 in a constant wet state, the incinerated ash 2 is stacked on a dump truck with the exposed surface covered with an airtight sheet 11 as shown in FIG. As shown in FIG. 3 (d), it is housed in a concrete mixer truck and transported to a disposal site. As described above, by covering the exposed surface of the incineration ash 2 with the airtight sheet 11 or by housing it in a concrete mixer truck that can be expected to have some airtightness, the emission of carbon dioxide gas during transportation can be suppressed as much as possible. . The dry ice 7 may be mixed again into the incineration ash 2 immediately before loading into a dump truck or the like.

Next, as shown in FIG. 9E, the incineration ash 2 is spread and spread in the bulldozer 4 at the disposal site, and the spread layer 12 is spread.
Are sequentially formed. In this case, dry ice may be mixed again into the incineration ash 2 by the processing method described in the first embodiment or the second embodiment.

As described above, according to the method for treating a high pH substance according to the present embodiment, when the incinerated ash 2 which is a high pH substance is temporarily placed, transported and landfilled, dry ice is added to the incinerated ash 2. 7 is mixed, the dissociation of Ca ²⁺ contained in the incineration ash 2 into water is suppressed, as in the above-described embodiments.
The incineration ash 2 can be immediately neutralized.

[0078] Therefore, there is no fear that a problem that a very long time is required when the incinerated ash is neutralized naturally and a problem that a large cost is required when the incinerated ash is neutralized with a chemical are eliminated.

Further, since dry ice emits only harmless carbon dioxide gas and has only the chemical reaction products of water and poorly soluble salts, it differs from neutralization with a chemical such as hydrochloric acid. The effect that mild persistence can be expected as long as dry ice is present without causing chemical problems, and heavy metals from incinerated ash due to a sudden drop in pH due to the use of chemicals such as hydrochloric acid There is also an operational effect that there is no need to worry about elution.

Although not specifically mentioned in the present embodiment, it goes without saying that embankment processing may be employed instead of landfill processing.

(Fourth Embodiment)

Next, a fourth embodiment will be described. In addition, the same reference numerals are given to components and the like that are substantially the same as those in the above-described embodiments, and description thereof is omitted.

In this embodiment, the method for treating high pH substances according to the present invention is applied to an existing incinerated ash landfill.
FIG. 6A is a cross-sectional view at that time. As shown in the figure, in the method for treating a high pH substance according to the present embodiment, first, in a landfill 22 made of incineration ash 2, a shaft 21 is excavated in the landfill, and then a dry shaft is dried in the shaft. After the ice 7 is charged, the shaft 21 is kept airtight and the landfill 22 is maintained in a constant wet state, for example, by immediately burying the incineration ash 2 in the shaft. Shaft 21
Can be drilled and excavated with an earth auger or a backhoe.

As described above, according to the method for treating a high pH substance according to the present embodiment, the shaft 21 is excavated in the landfill 22 made of the incinerated ash 2 which is a high pH substance, and Since the ice 7 is supplied, the dissociation of Ca ²⁺ contained in the incinerated ash 2 into water is suppressed as in the above-described embodiments, and the incinerated ash 2 is immediately neutralized. It becomes possible to make it.

Therefore, there is no problem that it takes a very long time to neutralize the incinerated ash naturally, and there is no problem that a large amount of cost is required to neutralize the incinerated ash. It is possible to start using landfill landfills, which are valuable land resources at low cost, at an early stage.

Also, since dry ice emits only harmless carbon dioxide gas and has only the chemical reaction product of water and poorly soluble salts, it differs from neutralization with a chemical such as hydrochloric acid. The effect that mild persistence can be expected as long as dry ice is present without causing chemical problems, and heavy metals from incinerated ash due to a sudden drop in pH due to the use of chemicals such as hydrochloric acid There is also an operational effect that there is no need to worry about elution.

Although not specifically mentioned in the present embodiment, the lower end of the shaft 21 may be communicated with a water collecting pipe 23 arranged at the bottom of the landfill 22 as shown in FIG.

In this configuration, the carbon dioxide gas sublimated from the dry ice 7 charged into the shaft 21 is discharged from the water collecting hole of the water collecting pipe 23 and the area of the landfill 22 where the carbon dioxide gas permeates. Can be expanded. In this case, it is desirable that the base end side of the water collecting pipe 23 be closed with a valve or the like so that the carbon dioxide gas is diffused only to the landfill 22.

[0089]

As described above, according to the method for treating a high pH substance of the present invention, when treating a high pH substance,
Each treatment was performed in a state where dry ice was mixed with the H substance, and thereafter the high pH substance mixed with dry ice was maintained in a constant wet state, so that the alkali component contained in the high pH substance was removed. It reacts with carbon dioxide sublimated from dry ice to convert it to carbonate, thereby making it possible to quickly neutralize high-pH substances.

[0090]

[Brief description of the drawings]

FIG. 1 is a construction procedure diagram of a method for treating a high pH substance according to a first embodiment.

FIG. 2 is a plan view of the same.

FIG. 3 is a graph showing the results of experiments confirming the effects of the method for treating a high pH substance according to the present invention.

FIG. 4 is a construction procedure diagram of a method for treating a high pH substance according to a second embodiment.

FIG. 5 is a construction procedure diagram of a method for treating a high pH substance according to a third embodiment.

FIG. 6 is a sectional view showing a method for treating a high pH substance according to a fourth embodiment.

[Explanation of symbols]

2 Incineration ash (high pH substance) 3a, 3b, 3c Spreading layer 6 Dry ice charging recess 7 Dry ice 21 Vertical shaft 22 Landfill 23 Water collecting pipe

 ────────────────────────────────────────────────── ─── Continuing on the front page (72) Inventor Yuki Kuroki 4-640 Shimoseito, Kiyose-shi, Tokyo F-term in Obayashi Corporation Technical Research Institute Co., Ltd. 4D004 AA33 AA36 BB03 CA15 CA35 CC12 CC20

Claims (6)

[Claims] Claims: 1. Incinerated ash, cement mixed soil, lime mixed soil,
When processing high pH substances such as concrete waste,
The above process is performed in a state where dry ice is mixed in the H substance, and then the high pH mixed with the dry ice is obtained.
High pH characterized by maintaining the substance in a constant wet state
How to treat the substance. 2. A dry ice charging concave portion is formed by excavating a dry ice charging concave portion in the previously formed spread layer, and then the dry ice is charged into the dry ice charging concave portion. 2. The method for treating a high pH substance according to claim 1, wherein the step of laying the high pH substance on the previously formed laying layer while forming a new laying layer is repeated. 3. A method of disposing the dry ice in a state covered with a heat insulating material on a pre-formed spread layer, and then removing the heat insulating material immediately before being covered with the high pH substance. 2. The method for treating a high pH substance according to claim 1, wherein the step of laying the high pH substance on the previously formed spreading layer to form a new spreading layer is repeated. 4. The method for treating a high pH substance according to claim 1, wherein the high pH substance after the treatment or the spread layer made of the high pH substance is maintained in an airtight state. 5. Incinerated ash, cement mixed soil, lime mixed soil,
In a landfill made of a high pH substance such as concrete waste, a shaft is excavated in the landfill, and then dry ice is charged into the shaft, and then the shaft is airtight and the landfill is moistened. A method for treating a high pH substance, characterized by maintaining the state. 6. The water collection pipe according to claim 5, wherein a lower end of the shaft is communicated with a water collection pipe disposed at a bottom of the landfill, and carbon dioxide sublimated from the dry ice is discharged from a water collection hole of the water collection pipe. A method for treating high pH substances.