JP2003300053A - Method for sorting and cleaning incineration ash - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method of making incineration ash having large grain sizes, such as coarse or middle grain ash, safely recyclable both as incineration ash for landfill and as aggregate by subjecting the incineration ash to classifying and to a safing treatment (a detoxification treatment), thereby performing the thorough detoxification of the incineration ash. <P>SOLUTION: The method for sorting and cleaning the incineration ash is provided with a coarse screen process step 8 for passing the incineration ash A formed by combusting wastes in an incineration furnace 2 in the state of dry ash through a coarse screen to remove bulky matter B from the incineration ash A, a fine screen process step 10 of passing the incineration ash passed the coarse screen through a fine screen to sort grain sizes and a water cleaning process step 18 of water cleaning the plus fine screen ash C failing to pass the fine screen and taking out the same. The plus fine screen ash C of the relatively large grain size is water cleaned, by which the fine ash having a high degree of contamination sticking to the circumference thereof is flushed away. The thorough detoxification treatment of the plus fine screen ash C is thus performed and the way to make the incineration ash lendable itself to the incineration ash for landfill and to make the incineration ash safely recyclable as the aggregate, such as HI-Cement raw material 24 and a covering material 28, is established. <P>COPYRIGHT: (C)2004,JPO

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 incineration residue (hereinafter referred to as incineration ash) discharged from an incinerator that incinerates municipal waste, industrial waste, and the like, and more specifically, a coarse sieve and The present invention relates to a method for sorting and cleaning incinerated ash that classifies incinerated ash by two-step screening of a fine sieve and cleans the incinerated ash that has not passed through the fine sieve to make it harmless and to reuse it.

[0002]

2. Description of the Related Art The total amount of municipal waste, industrial waste, and the like is increasing year by year, and the burden on each municipality to handle these wastes has increased dramatically. The treatment method of constructing artificial islands by reclaiming the coast and the like without incinerating municipal waste is now strictly regulated from the viewpoint of pollution prevention and the reason that the total amount of waste is too large.

Therefore, a method is generally used in which municipal waste or industrial waste is incinerated in an incinerator to reduce the total volume, and the incinerated ash discharged from the incinerator is sent to landfill.
FIG. 3 is a processing procedure diagram illustrating a first conventional example of a method for processing incinerated ash.

The hopper 60 of the incinerator 2 is charged with dust 60,
This dust 60 is burned in a combustion furnace to form incineration ash 62. The incinerated ash 62 is put into an ash cooling device 66 together with the boiler ash 64 and cooled to a required temperature.

All the cooled ash is transferred to the ash discharging conveyor 68.
And is deposited in the ash pit 70. The ash 72 accumulated in the ash pit 70 is loaded on a truck 76 waiting outside by using an ash crane 74. The ash 72 loaded on the truck 76 is transferred to a landfill and used for landfill.

However, since the amount of garbage itself is rapidly increasing in modern citizen life, even if the volume is reduced by incineration, the total amount of incinerated ash itself reaches a huge amount. Therefore, in the treatment method of sending all of the incineration ash to the landfill, the surplus incineration ash inevitably appears due to the rapid decrease in the landfill, and the problem of how to solve the situation in which this excess incineration ash increases appears. ing.

[0007] In order to solve such a situation, there is a measure to reduce the total amount of incinerated ash to be sent to landfill by reusing the active ingredient in the incinerated ash instead of landfilling all of the incinerated ash. It is needed. Further, it has been pointed out that heavy metals are contained in the incinerated ash and that dioxins are produced depending on the incineration temperature, and it has been pointed out that the incinerated ash needs to be treated to be harmless.

FIG. 4 is a processing procedure diagram for explaining a second conventional example of a method for treating incinerated ash. This conventional example shows a conventional method in which the incineration ash 62 discharged from the incinerator 2 is subjected to particle size adjustment (classification treatment) or detoxification treatment to divide the incineration ash into a reuse group and a landfill group.

The incineration ash 62 generated by the incinerator 2 is sent to the incineration ash processing step by the ash discharging conveyor 68.
In the pretreatment process 78, the incineration ash 62 is subjected to magnetic separation treatment and particle size adjustment. First, in the magnetic separation process, magnetic substances and non-magnetic substances are separated, and useful metals such as iron are sorted as magnetic substances 82 and reused.

Next, the particle size of the incinerated ash is adjusted (classification process).
Is applied. This particle size adjustment is performed according to the following principle. According to the study by the present inventors, as already disclosed in Japanese Patent Laid-Open No. 2000-233174, the proportion of dioxins, heavy metals and the like strongly depends on the particle size of particles constituting incinerated ash. There is.

Coarse ash with a particle size of 20 mm or more, 5 to 20 m
m is called medium ash, 2 to 5 mm is called fine ash, and 2 mm or less is called fine ash. At this time, dioxins and heavy metals in the coarse ash and medium ash are below the standard value, dioxins in the fine ash are below the standard value but heavy metals are above the standard value, and dioxins and It was discovered that both heavy metals exceeded the standard value.

[0012] In the coarse ash and medium ash, since dioxins and heavy metals are below the standard values, special treatment of dioxins and heavy metals is unnecessary, and incineration ash with a size of 5 mm or more remains as it is. It can be sent to landfill with.

In fine-grained ash, dioxins are below the standard value, but heavy metals are above the standard value, so heavy metal immobilization treatment is applied. In fine ash, both dioxins and heavy metals exceed the standard values, so melting treatment is performed to decompose dioxins and fix heavy metals. Since the heavy metal immobilization treatment can also be realized by a melting treatment, both fine ash and fine ash can be rendered harmless at once by the melting treatment.

According to this concept, by adjusting the particle size in the pretreatment step 78, coarse ash and medium ash having a particle size of 5 mm or more are sent to landfill as unsuitable materials 80, and fine ash and fine particle having a particle size of 5 mm or less. After the ash is melted and solidified through the melting furnace process 84,
It will be processed as slag 86.

[0015]

According to this conventional treatment method, incineration ash is classified according to its particle size and divided into ash for landfill and ash not for landfill. Can be. However, due to subsequent research,
It has been found that there is an essential problem with coarse-grained ash and medium-grained ash that have been sent to landfill in their original form as safe.

It has already been explained that the incineration ash having a smaller particle size contains dioxins and heavy metals. In particular,
It was found that the fine ash containing both dioxins and heavy metals is, so to speak, a powder, and a large amount is attached around the particles of coarse ash and medium ash having a large particle size.

When the coarse-grained ash and the medium-grained ash are directly subjected to landfill without any treatment, the attached fine-grained ash is mixed in the landfill sand. Of course, the amount of adhered fine ash is 1/100 to 1/1000 of the total incineration ash for landfill.
Since it is only about 0, it can be said that it is much safer than when all of the incinerated ash was landfilled.

However, the recent trend of environmental protection has reached a level at which the danger is reduced to zero as much as possible. Therefore, according to this safety concept, even the adhered fine ash is dangerous. Therefore, in addition to classifying the incinerated ash, some kind of detoxification treatment is inevitably required for the incinerated ash such as coarse ash and medium ash.

Therefore, according to the present invention, incineration ash having a large particle size such as coarse ash or medium ash obtained by classifying incineration ash is subjected to a safety treatment for removing small ash adhering to the ash. Therefore, it is safe to detoxify these incinerated ash and send it to landfill, and it is an object to provide a selective cleaning method of incinerated ash that can be safely reused as aggregate other than landfill. .

[0020]

The present invention has been made in order to achieve the above object, and the first invention thereof is that the incineration ash produced by burning waste in an incinerator is a dry ash. Coarse sieving process that removes coarse particles from incinerated ash through a coarse sieve, fine sieving process that selects the particle size by passing the incinerated ash that has passed through the coarse sieve through a fine sieve, and fine sieving top ash that does not pass through the fine sieve. This is a method for selective cleaning of incinerated ash, which is characterized by having a water cleaning step in which the ash is washed out with water. Ashes are washed away, and as a result, the fine sieving top ash can be made safe and used as landfill incineration ash or reused as aggregate.

A second aspect of the present invention is a cooling step of using the cleaning wastewater discharged from the water cleaning step as cooling water for the fine sieving lower ash that has passed through the fine sieve, and water for purifying the wastewater discharged from this cooling step. It is a method of selective cleaning of incineration ash, in which the treatment step and the treated water purified by this water treatment step are returned to the water washing step and reused as washing water, and as a result, the washing water of fine sieving top ash is recycled. It is possible to improve the economical efficiency and to further enhance the environmental safety by enclosing the cleaning water in the system.

A third aspect of the present invention is a method for selecting and washing incinerated ash which is used as a raw material for high cement by drying fine sieving on fine sieve that has been washed with water and then finely pulverizing the ash. The fine sieving top ash can be converted into a reusable form to improve the reuse efficiency of incineration ash.

A fourth aspect of the present invention is a method for selecting and washing incinerated ash that is used as a covering material by drying the ash on the fine sieve that has been washed with water, and then crushing it to adjust the particle size. It is possible to pave the way for the safe use of the fine sieving top ash as soil cover material.

[0024]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of a method for sorting and cleaning incinerated ash according to the present invention will be described in detail below with reference to the drawings.

FIG. 1 is a process diagram of a method for sorting and cleaning incinerated ash according to the present invention. The incineration ash A generated by the incinerator 2 is conveyed by the conveyor 6 and sent to the coarse sieving step 8. The coarse sieve used in this coarse sieving step 8 is about 50.
A coarse product B having a grain size of 50 mm and a particle size of 50 mm or more is left, and incineration ash having a particle size of 50 mm or less is passed.

In this embodiment, the coarse sieve has a size of 50 mm.
However, depending on the particle size of the incineration ash discharged from the incinerator, for example, it may be 40 mm or 100 mm. If the incinerated ash has a large particle size, the coarse sieving mesh should have a large size, and if the incinerator ash has a small particle size, the coarse sieving mesh should have a small mesh size.

In the present invention, the incineration ash having a size of coarse sieve or larger is defined as a coarse product B. In this embodiment, the size of the coarse sieving is set to 50 mm. It becomes B. The coarse product B is conveyed to the outside by an ash extraction process 12 including an ash extraction conveyor and is sent to the final disposal process 14.

The incinerated ash that has passed through the coarse sieving step 8 is sent to the fine sieving step 10. The fine sieving mesh used in the fine sieving step 10 is set to about 5 mm. Of course, the mesh of the fine sieve can be changed, and in some cases it can be adjusted to 10 mm, and in some cases to 2 mm.

In this embodiment, the fine sieve has a size of 5 mm.
Therefore, the particle size of fine ash C on the fine sieve which is blocked by the fine sieve and remains on the fine sieve is 5 to 50 mm. As described above, according to the definition of Japanese Patent Laid-Open No. 2000-233174,
Since 20 mm or more is coarse grain ash and 5 to 20 mm or more is medium grain ash, it is considered that fine sieve top ash C is composed of coarse grain ash and medium grain ash.

It is known that the coarse-grained ash and the medium-grained ash mainly consist of earth and sand, glass, pottery, etc., and contain almost no dioxins or heavy metals. However, finer ash adheres to the surroundings, and it is also known that these fine ash contain a relatively large amount of dioxins and heavy metals.

Therefore, the fine ash C on the fine sieve is sent to the water washing step 18 in order to remove fine ash containing dioxins and heavy metals. When the washing water W is supplied to the water washing step 18 and the fine sieving top ash C is stirred, fine ash is removed from the fine sieving top ash C. The washed fine sieve ash E thus obtained is sent to the drying step 20.

The dried and washed fine sieve top ash E is effectively used through two passes. The first pass is the raw material for high cement and the second pass is the soil cover material. First, the washed fine sieving top ash E is finely pulverized by the fine pulverization step 22 to such an extent that it can be used as a high cement raw material. Even if it is pulverized, it is extremely safe because it contains no dioxins or heavy metals. Therefore, the high cement raw material 24 is produced from the incinerated ash and reused as an effective resource.

Next, as a second pass, the washed fine sieve top ash E is sent to the crushing particle size adjusting step 26. This step 2
In No. 6, crushing is performed to an appropriate size, and the covering material 28 having the most uniform particle size is produced from the incinerated ash. By covering the particle size in multiple stages, it is possible to produce soil covering materials with multiple particle sizes.

The incinerated ash that has passed through the fine sieving step 10 is called fine sieving bottom ash. In this embodiment, since the fine sieve has a size of 5 mm, the particle size of the fine sieve lower ash D is about 5 mm or less. According to the definition of Japanese Patent Laid-Open No. 2000-233174, 2
Since ~ 5 mm is fine-grained ash and 2 mm or less is fine-grained ash, it is considered that the fine sieve lower ash D is composed of fine-grained ash and fine-grained ash.

Fine ash contains a relatively large amount of heavy metals,
Since the fine ash contains a large amount of heavy metals and dioxins, the fine sieving bottom ash D needs to be detoxified. As an example of this detoxification process, the fine sieving lower ash D may be sent to the melting process step 16 as shown by a broken line. Dioxins are decomposed and rendered harmless by the melting process, and heavy metals are sealed inside by melting and solidification, and the heavy metals do not leak to the outside.

In this embodiment, as shown by the solid line, the fine sieving lower ash D is sent to the ash removing step 12 and then to the final disposal step 14 by the ash removing conveyor. Final disposal process 1
As 4, there are, for example, a firing step of decomposing dioxins, a heavy metal fixing treatment step of confining heavy metals inside, and other necessary final treatments.

In the ash removal step 12, the fine sieving bottom ash D
Cooling water is used to cool the. For example, in the case where an ash discharging conveyor is used, cooling water is collected in the ash discharging conveyor water tank to cool the fine sieving lower ash D.

At this time, as the cooling water, a water washing step 18 is performed.
It is efficient to use the cleaning drainage water W1. After cooling, the wastewater W2 discharged from the ash extraction process 12 is subjected to a purification treatment by the water treatment process 30. This water treatment process 3
At 0, harmful heavy metals and salts can be completely removed by appropriately combining various wastewater treatment methods in accordance with a physical filtration method, if necessary. The purified treated water W3 is fed back to the water washing step 18 and reused in the water washing step of the fine ash C on the fine sieve.

Since the fine ash separated from the fine sieve ash C is mixed in the wash water, it is necessary to avoid discharging the wash water to the environment. In the present invention, the wash water W is confined and circulated for use without flowing out to the outside, so that it is not discharged to the environment and constitutes a very safe water treatment system for the environment.

FIG. 2 is a schematic explanatory view of an example of a water cleaning apparatus used in the water cleaning step of the present invention. Although any cleaning device can be used as the water cleaning device 40, a rotary drum system is adopted in this embodiment. As shown in the figure, a cylindrical rotary drum screen 44 is arranged in the casing 42, and is rotationally driven by the rotational drive units 46.

On the outer peripheral surface of the rotary drum screen 44, the cleaning water W is discharged in a shower form from the outer surface cleaning machine 48, and at the same time, the cleaning water W is discharged in a shower shape from the inner surface cleaning machine 50 on the inner peripheral surface. It Therefore, the supply pipe 52
When the fine sieving upper ash C is supplied from the above, the fine sieving upper ash C is stirred and washed by the cleaning water W as the rotary drum screen 44 rotates, and fine ash is separated.

Washed fine sieving top C is washed drainage W1
Is discharged from the discharge pipe 54 together with, and the washed fine sieve upper ash E and the cleaning waste water W1 are separated on the way. Thereafter, as described above, the washed fine sieve ash E is sent to the drying step 20, and the washing wastewater W1 is sent to the ash removing step 12 as cooling water. After that, the steps as described above are followed.

The essential point of the present invention is to wash fine sieving top ash C with water to separate and remove fine ash adhering to fine sieving top ash C, and pass this cleaned fine sieving top ash E to landfill. Or to effectively use it as a high cement raw material or soil covering material. Effective utilization is not limited to high cement raw materials and soil covering materials.

Since the separated fine ash may contain heavy metals and dioxins in excess of the standard value, it is melted together with the fine sieving bottom ash D to decompose dioxins or after melting. It is solidified and sealed with heavy metals inside to detoxify it.

The size of the fine sieve is not limited to 5 mm, and the degree of contamination of the fine ash or fine ash on the fine sieve and the degree of purification after washing can be adjusted by adjusting the size of the fine sieve.
This is based on the discovery of a significant fact that the content of heavy metals and dioxins changes depending on the particle size of incinerated ash particles.

Further, since it is highly possible that heavy metals and dioxins are mixed in the cleaning wastewater, a method is adopted in which the wastewater is purified and circulated and not released to the environment. This further ensures the safety of the environment.

The present invention is not limited to the above embodiments, and various modifications and design changes within the scope of the technical idea of the present invention are included in the technical scope thereof. Needless to say.

[0048]

EFFECTS OF THE INVENTION According to the first aspect of the invention, since the incinerated ash is passed through a two-stage sieve consisting of a coarse sieving step and a fine sieving step and the fine ash on the fine sieving which does not pass through the fine sieving is washed with water, the particle size is relatively large. The fine ash on the fine sieve of the above is washed with water to wash away the fine ash adhering to the surrounding area. As a result, the fine ash on the fine sieve can be safely used for incineration ash for landfill and reused as aggregate. ing. Therefore, this is an epoch-making invention that ensures the safety of the landfill soil even when it is sent to landfill and establishes a positive way to use the aggregate by detoxifying the incineration ash.

According to the second aspect of the present invention, the washing wastewater of the fine sieving upper ash is used as cooling water for the fine sieving lower ash, and the fine ash is used as a washing water for the fine sieving upper ash again after purification treatment. Since the contained cleaning wastewater is recycled without being discharged to the environment, it constitutes a water treatment system that is extremely safe for the environment. Also, if fine ash is separated from wastewater during this circulation, it can be subjected to final disposal such as melting treatment and firing treatment together with fine sieving lower ash, making fine sieving lower ash and fine ash harmless. The processing can be made efficient.

According to the third aspect of the invention, the ash on a fine sieve that has been washed with water is dried and then finely pulverized to be used as a raw material for high cement. Therefore, it has conventionally been used only for landfill. It established a path for positive and effective utilization of incineration ash.

According to the fourth invention, the ash on the fine sieve which has been washed with water is dried and then crushed to be used as a covering material by adjusting the particle size. Therefore, similar to the third invention. , It has established a path for positive and effective utilization of incinerated ash that had to be used only for landfill. As described above, the present invention has excellent practical utility.

[Brief description of drawings]

FIG. 1 is a process diagram of a method for sorting and cleaning incinerated ash according to the present invention.

FIG. 2 is a schematic explanatory view of an example of a water cleaning apparatus used in the water cleaning step of the present invention.

FIG. 3 is a processing procedure diagram illustrating a first conventional example of a method for processing incinerated ash.

FIG. 4 is a processing procedure diagram illustrating a second conventional example of a method for processing incinerated ash.

[Explanation of symbols]

2 is an incinerator, 6 is a conveyor, 8 is a coarse sieving process, 10 is a fine sieving process, 12 is an ashing process, 14 is a final disposal process, 16 is a melting treatment process, 18 is a water washing process, 20 is a drying process, 22 is a fine grinding process, 24 is a high cement raw material,
26 is a crushed particle size adjusting step, 28 is a soil covering material, 30 is a water treatment step, 40 is a water cleaning device, 42 is a casing, 44 is a rotary drum screen, 46 is a rotary drive unit, 48 is an outer surface cleaning machine, and 50 is an inner surface cleaning. Machine, 52 is a supply pipe, 54 is a discharge pipe, 60 is dust, 62 is incinerated ash, 64 is boiler ash, 66 is an ash cooling device, 68 is an ash discharge conveyor, 70 is an ash pit, 72 is ash, and 74 is ash. Crane, 76 is a truck, 78 is a pretreatment process, 80 is an unsuitable material, 82 is a magnetic material,
84 is a melting furnace process, 86 is slag, A is incinerated ash, B is coarse, C is fine sieve top ash, D is fine sieve bottom ash, E is washed fine sieve top ash, W is wash water, W1 is Wash drain, W2
Is drainage and W3 is treated water.

─────────────────────────────────────────────────── ─── Continuation of front page (51) Int.Cl. ⁷ Identification code FI theme code (reference) B07B 1/00 C04B 7/28 C04B 7/28 7/38 7/38 B09B 5/00 ZABN (71) Application People 500417764 Akira Nakajima 3-17-19 Komakawa, Higashi Sumiyoshi-ku, Osaka-shi, Osaka (71) Applicant 502121845 Ryuji Ikushima 2-64-25, Tsudamoto-cho, Hirakata-shi, Osaka (71) Applicant 000183266 Sumitomo Osaka Cement Co., Ltd.Tokyo 6-28 Rokuban-cho, Chiyoda-ku 28 (71) Applicant 500177190 Hanshin Environmental Maintenance Co., Ltd. 5-9-6-1002 Nishinakajima Nishinakajima, Yodogawa-ku, Osaka-shi, Osaka (72) Masahide Nishigaki 2-chome, Kirakuji-cho, Amagasaki-shi, Hyogo 2-33 In stock company Takuma (72) Inventor Takeshi Shinohara 2-32 Kinrakuji-cho, Amagasaki-shi, Hyogo Prefecture In-house company Takuma (72) Inventor Eiji Tashiro Kobe, Hyogo Prefecture 3-9-9 Tsukamoto-dori, Hyogo-ku (72) Inventor Yoshiyoshi Hirono 5-16-1 Mikanodai, Kawauchi-Nagano City, Osaka Prefecture (72) Akira Nakajima 3-17-19 Komagawa, Higashi-Sumiyoshi-ku, Osaka City, Osaka Prefecture (72) Inventor Ryuji Ikushima 2-64-25, Tsudamotomachi, Hirakata-shi, Osaka (72) Inventor Takao Koide 7-55, Minamienkajima, Taisho-ku, Osaka Sumitomo Osaka Cement Co., Ltd. (72) Invention Person Mori Yoshinobu 5-8-29 Nishinakajima, Yodogawa-ku, Osaka Local Building No. 3 Shin-Osaka 204 Hanshin Environmental Maintenance Co. F-Term (Reference) 4D004 AA36 AB03 AB07 BA02 CA08 CA10 CA40 CA42 CB01 CB09 CB44 CC03 4D021 AB02 EA10 4D071 AA65 AB12 AB22 AB33 AB48 CA03 DA01 DA15

Claims (4)

[Claims] 1. A coarse sieving process in which incinerator ash generated by burning waste in an incinerator is passed through a coarse sieve as dry ash to remove coarse particles from the incinerator ash, and an incinerated ash that has passed through the coarse sieve is finely divided. A method for sorting and cleaning incinerated ash, which comprises a fine sieving step of selecting a particle size through a sieve and a water washing step of washing and removing the ash on the fine sieve that does not pass through the fine sieve. 2. A cooling process in which the cleaning wastewater discharged from the water cleaning process is used as cooling water for the fine sieving bottom ash that has passed through a fine sieve, and a water treatment process for purifying the wastewater discharged from this cooling process. The method for sorting and cleaning incinerated ash according to claim 1, wherein the treated water purified by the water treatment step is returned to the water washing step and reused as washing water. 3. The method for sorting and cleaning incinerated ash according to claim 1, wherein the ash on the fine sieve that has been washed with water is dried and then finely pulverized to be a raw material for high cement. 4. The method for selective cleaning of incinerated ash according to claim 1, wherein the fine ash on the fine sieve that has been washed with water is dried and then crushed to be used as a covering material by adjusting the particle size.