JP2022145409A - Refuse incineration ash processing method and processing system - Google Patents

Abstract

To separate a foreign matter such as a wire and the like from ashes.CONSTITUTION: Main ashes from a refuse incinerator are processed by a roll screen, and are separated into screen lower components that have fallen to a lower side of the roll screen and screen upper components which have passes an upper side thereof. Next, the screen lower components and the screen upper components are separately processed by magnetic force to sort magnetically attracted substances. The screen lower components and the screen upper components after sorting the magnetically attracted substances are screened into non-magnetically attracted foreign matters and ashes.SELECTED DRAWING: Figure 1

Description

This invention relates to the treatment of bottom ash in refuse incineration ash.

It is known to separate metal foreign matter and solid foreign matter from bottom ash in garbage incineration ash, and use the remaining ash as a raw material for cement or the like. For example, in Patent Document 1 (Patent No. 4979164), bottom ash is treated with a sieve with an opening of 20 mm and a magnetic separator to separate large foreign matters and metals from the ash. Next, after pulverizing the ash with a pulverizer to an average particle size of 1 mm or less, it is processed through a sieve with an opening of 5 mm to separate small solid foreign matters. Thereafter, the under-sieved components are washed with water to separate solids, and the waste liquid is treated as waste water.

Patent 4979164

By the way, bottom ash sometimes contains wire-like foreign matter. When a wire-like foreign matter is passed through a vibrating sieve, which is a typical sieve, the wire-like foreign matter rises due to vibration and may pass through the mesh of the sieve in a dancing manner. Furthermore, since a large amount of incineration ash adheres to the wire-like foreign matter that has passed through the sieve, it may not be adsorbed by the magnetic separator. Since it is difficult to sufficiently remove the wire-like foreign matter by using a vibrating sieve or a magnetic separator, there is a possibility that the wire-like foreign matter may be mixed into the cement raw material.

An object of the present invention is to more reliably separate wire-like foreign matter from ash.

In the garbage incineration ash treatment method of the present invention, the bottom ash from the garbage incinerator is treated with a roll screen, and separated into an under-screen component that has fallen to the lower side of the roll screen and an on-screen component that has passed through the upper side of the roll screen. A roll screen step, a first magnetic separation step in which the under-screen component and the on-screen component are separately processed by magnetic force to sort out the magnetic substances, and after the magnetic substances are sorted, the under-screen component and the on-screen component are separated into a non- By performing a sieving step of sieving into magnetically attracted foreign matter and ash, the refuse incineration ash is separated into magnetically attracted foreign matter and non-magnetically attached foreign matter and ash. Note that magnetic separation means sorting into magnetic substances and non-magnetic substances by magnetic force.

The garbage incineration ash treatment system of the present invention comprises a roll screen for treating main ash from a garbage incinerator, a screen under-screen component falling below the roll screen, and a screen over-screen component separately treated by magnetic force. Equipped with a magnetic separator for sorting out the substances, and a sieve for sieving the components under the screen and the components on the screen after sorting the magnetic substances into non-magnetic foreign substances and ash, and the garbage incineration ash is divided into the magnetic substances, It is configured to separate non-magnetic foreign matter and ash.

A roll screen is equipped with rotating rolls, and is a device that allows small objects to drop through rolls and openings in the rolls, etc., and transports large objects over the openings. Since the roll screen does not vibrate, the wire-like foreign matter does not stand up due to the vibration and drop vertically from the opening, and the wire-like foreign matter is conveyed over the opening. In the roll screen, wire-like foreign matters and other foreign matters are mainly sorted by their long diameters, and become on-screen components. Foreign matter such as screws with a small major diameter, gravel, and pieces of pottery falls through the opening of the roll screen together with ash and becomes a component under the screen.

By magnetically treating the components on the screen, wire-like foreign matter is separated by magnetic force. By magnetically treating the under-screen component separately from the on-screen component, small metal screws and the like in the ash are separated from the ash. After removing the magnetized substances, the on-screen component and the under-screen component are sieved to separate non-magnetized foreign matters.

In this manner, wire-like foreign substances and the like are removed from the bottom ash, and other magnetically attracted foreign substances and non-magnetic substances are also removed from the bottom ash. Since the foreign matter can be sufficiently removed from the bottom ash, the bottom ash after the foreign matter separation is suitable as a raw material for cement or the like. Wire-like foreign matter can also be recovered from bottom ash.

Preferably, the crushing step of crushing the on-screen components with an impact crusher is performed between the roll screen step and the first magnetic separation step. The crushing makes it easier to remove the ash that has entered the interior of large foreign objects such as empty cans, and part of the ash adhering to foreign objects such as wires also peels off. As the ash falls off, the foreign objects become smaller in size and lighter. Since the ash is removed and the weight is reduced, foreign matter such as wires and large foreign matter can be easily sorted out by magnetic force.

Preferably, when the amount of foreign matter in the main ash is large, the roll screening step is performed, and when the amount of foreign matter in the main ash is small, the roll screening step is omitted, and the main ash is processed by magnetic force. A second magnetic separation step is performed to sort out the magnetic substances. The bottom ash containing less foreign matter omits the roll screen step, which simplifies the disposal of the incinerated ash. The amount of foreign matter may be determined each time incineration ash is received, or may be determined in advance for each generation source of incineration ash. The amount of foreign matter is determined by passing the incinerated ash through a sieve with the same mesh size as the sieve used in the sieving step.

Preferably, in the magnetic separation step, the under-screen component and the on-screen component are processed by separate magnetic separation devices. That is, the small magnetic substances in the under-screen component and the large magnetic substances in the on-screen component are magnetically separated separately. Since the on-screen component has a lower ash content than the under-screen component, it is easier to perform magnetic separation if it is not mixed with the under-screen component. Also, the small magnetized foreign matter in the under-screen component does not have a very large amount of ash adhered. At least it's not thick and covered with ash. Therefore, they can be easily sorted by magnetic force.

Preferably, a wet step of adding water to at least part of the ash sieved in the sieving step to treat it, and a water washing step of storing the magnetic substance and the non-magnetic foreign matter in separate water-permeable baskets and washing them with water. and using at least a portion of the effluent from the water washing step, for example containing ash, in the wet step. It can be easily washed with water by using a water-permeable basket. Also, wastewater from the water washing step can be used in the wet step and reused within the treatment system.

A diagram showing an overview of the first embodiment FIG. 2 is a plan view of the main part of the roll screen used in the first embodiment; Vertical cross-sectional view of the roll in the roll screen used in the first embodiment A diagram showing an overview of the second embodiment Schematic cross-sectional view of a net basket and a water tank used in the second embodiment A diagram showing an overview of the third embodiment A diagram showing an overview of the fourth embodiment

Examples for carrying out the present invention are shown below. The scope of the present invention should be determined according to the understanding of those skilled in the art based on the description of the claims, taking into consideration the description of the specification and well-known techniques in this field.

Example 1
1 to 7 show an embodiment of the method and system for treating incinerated ash, and FIGS. 1 to 3 show the first embodiment. As shown in FIG. 1, a receiving hopper 1 receives bottom ash from an incinerator and feeds it to a roll screen 2 . Bottom ash is incineration ash discharged from the bottom of a stoker furnace, etc., and the ash discharged together with exhaust gas is called fly ash.

The roll screen 2 is shown in FIGS. 2 and 3. FIG. The roll screen 2 has a plurality of rolls 20, and a set of a small-diameter flange 21 and a large-diameter flange 22 protrudes radially from a roll shaft 24 of each roll 20. As shown in FIG. Note that these flanges 21 and 22 are sometimes called discs in the industry. In adjacent rolls 20, 20, the large-diameter flange 22 and the small-diameter flange 21 face each other, and the gap between the facing flanges 21, 22 is narrow. Each roll 20 is provided with a plurality of pairs of flanges 21 and 22 . Between the roll shafts 24, 24, there is an opening 25 sandwiched by the left and right flanges 21, 22. Ashes in the bottom ash and small foreign matter fall from the opening 25, and large foreign matter is conveyed without passing through the opening 25. be.

As shown in FIG. 3, the flanges 21 and 22 are shaped such that the central portions of the sides of the polygonal sides of triangles to pentagons bulge outward. With the flanges 21 and 22 having such shapes, it is difficult for foreign matter to pass through the gap between the flanges 21 and 22 . Assuming that the size of the opening 25 in the direction parallel to the roll axis 24 is a, and the size in the direction perpendicular to the roll axis 24 is b, the ratio a:b is preferably about 1:1 to 1:2. The size a is preferably, for example, 5 mm or more and 50 mm or less, and the size b is preferably, for example, 10 mm or more and 60 mm or less. The rolls 20 rotate in the same direction and bottom ash is carried by the rolls 20 . The component that has fallen from the opening 25 is defined as the under-screen component, and the component that has not fallen is defined as the above-screen component.

Adjacent openings 25 and 25 are separated by flanges 21 and 22 so that wire-like foreign matter cannot pass through the gap between flanges 21 and 22. FIG. In order for the wire-like foreign matter to pass through the opening 25, it must stand up in the vertical direction due to vibration, but the roll 20 does not apply vibration to the bottom ash. Therefore, the wire-like foreign matter does not pass through the opening 25 and is discharged as an on-screen component.

The number of rolls 20 is arbitrary, and the flanges 21 and 22 may be circular instead of polygonal. Further, instead of a combination of large diameter and small diameter flanges, flanges having the same diameter may be arranged facing each other or alternately between adjacent rolls. However, in the roll screen 2 of FIGS. 2 and 3, it is difficult for the wire-like foreign matter to pass through the adjacent openings 25, 25, so that the wire-like foreign matter is less likely to be mixed into the under-screen component.

Magnetic substances are separated from the under-screen component and the on-screen component that have fallen through the openings 25 of the roll screen 2 by a magnetic separator. Since the under-screen component and the on-screen component have different sizes of magnetic substances (mainly metals), it is preferable to treat them with different magnetic separators 4 and 5 . The magnetic separators 4 and 5 may be of an electromagnetic type, or may be of a magnet pulley having a permanent magnet attached to the end of a belt conveyor so as to change the falling position between magnetic substances and other substances.

The ash and solid foreign matter that have passed through the magnetic separators 4 and 5 are passed through a sieve 6 to separate the solid foreign matter from the ash. The sieve 6 is, for example, a vibrating sieve, and preferably has an opening of 8 mm or more and 25 mm or less, but the type of sieve and the range of opening are arbitrary. The ash that has passed through the sieve 6 is stored in a silo 7 or the like, a part of which is shipped as unwashed ash, and the rest of the ash is desalted by wet pulverization and water washing and then shipped. Also, the magnetic substances in the magnetic separators 4 and 5 are collected as magnetic foreign substances, and the sieved components in the sieve 6 are collected as non-magnetic foreign substances. As described above, it is possible to prevent wire-like foreign matter from passing through the sieve 6 and mixing with the ash to be shipped.

Example 2
A second embodiment is shown in FIGS. 4 and 5, and is the same as the embodiment of FIGS. 1 to 3 except for the points specifically pointed out. In a second embodiment, the on-screen components of the roll screen 2 are crushed by an impact crusher 3 . The impact crusher 3 has, for example, a plurality of hammers attached to a rotary shaft, and by rotating the rotary shaft, impacts are applied from the hammers to the object to be processed. In the impact crusher 3, the object to be processed is sandwiched between a fixed gate and a rotating hammer, or between a hammer of one rotating shaft and another rotating shaft to apply an impact. Such impact crushers are put to practical use as crushers or shredders. A crusher that uses a toggle mechanism to hold the material between a movable jaw and a fixed plate and crush the material by gradually increasing the pressure is not suitable for separating ash and foreign matter.

A large amount of ash adheres to the foreign matter on the screen. If the ash is not peeled off from the foreign matter, the recovery rate of the ash will decrease, and the attached ash may prevent the subsequent magnetic separator from separating the magnetic substances. Therefore, by applying an impact with the impact crusher 3, the components on the screen (metallic and non-metallic foreign matter) are crushed and the ash adhering to the foreign matter is peeled off. When a shock is applied, the ash adhering to the foreign matter is peeled off. Ash may have entered the inside of a container such as an empty can or bottle, but crushing the container can separate the ash from the inside. Also, the ash adhering to the foreign matter is partially peeled off, and the foreign matter becomes smaller and lighter. In addition, clumps of ash are also crushed and separated into ash and foreign matter. For these reasons, the magnetically-attached foreign matter can be reliably sorted out by the subsequent magnetic separator 5, and the ash recovery rate is also improved. If the impact crusher 3 is not passed, the magnetized foreign matter may not be magnetically separated by the magnetic separator 5 .

The magnetic substances from the magnetic separators 4 and 5 are housed in a net basket 8 in a water tank 10 and washed with water. Similarly, foreign matter remaining on the sieve 6 is placed in a net basket 9 in a water tank 11 and washed with water. The net baskets 8 and 9 and the water tanks 10 and 11 are schematically shown in FIG. When the mesh cages 8 and 9 are sprinkled with water or vibrated in the water tanks 10 and 11 by a device (not shown), the ash attached to the magnetic substances (magnetic substances such as metals) and non-magnetic foreign substances is removed. can be dropped. Removing the ash facilitates the recycling of magnetic and non-magnetic foreign matter. The net baskets 8 and 9 may be water-permeable and impervious to foreign matter, and may be baskets other than net baskets.

The ash stored in the silo 7 from which foreign matter and the like have been removed is transported to, for example, a cement factory and used as part of the raw material for cement clinker. Cement clinker has an upper chlorine concentration limit. Therefore, part of the ash from which foreign matter has been removed is pulverized by a wet pulverizer 13 and immersed in water in a desalting tank 14 to elute chlorine. Next, ash and water are separated by a solid-liquid separator 15 such as a filter press. In this way the average salinity of the treated ash is reduced to acceptable levels. Further, the waste water separated by the solid-liquid separator 15 is treated by the waste water treatment device 16, and a part of the waste water is discharged after conforming to the environmental standards. When the fly ash generated at the garbage incineration plant is also treated, the dioxin in the fly ash is removed by the de-dioxin device 12 . Then, the fly ash after treatment is treated in the desalting tank 14 .

The wash water used in the water tanks 10, 11 to separate foreign matter from ash contains ash. Even if the wastewater from the water tanks 10 and 11 is used in the wet pulverizer 13 or the desalting tank 14, for example, in a state containing ash, it does not contaminate the object to be treated or the surrounding equipment. Therefore, the waste water from the water tanks 10, 11 is reused in the wet step (wet milling or desalination) within the treatment system. In addition, when the ash content in the waste water is high, the waste water may be treated by the solid-liquid separator 15 . It is also possible to settle the ash from the wastewater, use the supernatant in the wet step, and treat the sediment in the solid-liquid separator 15 . Additionally, the wastewater can be used in the wet step without treatment to separate the ash from the wastewater.

Example 3
FIG. 6 shows a third embodiment, which is the same as the embodiment of FIGS. 1-3 except as otherwise noted. In the third embodiment, when the amount of foreign matters in bottom ash is large, it is treated with a roll screen, and magnetic substances are separated by magnetic separators 4 and 5 . When the amount of foreign matter in the bottom ash is small, the treatment with the roll screen is omitted, and the bottom ash is treated with the magnetic separator 4 via the receiving hopper. The amount of foreign matter may be determined each time incinerated ash is received, or may be determined in advance for each source of incinerated ash. The amount of foreign matter is determined by passing the incinerated ash through a sieve with the same mesh size as the sieve used in the sieving step. Since the sieve 6 used in the sieving step has, for example, an opening of 8 mm or more and 25 mm or less, a sieve with an opening of 8 mm or more and 25 mm or less is used for determining the amount of foreign matter. In the third embodiment, since bottom ash containing less foreign matter does not need to be treated by the roll screen 2 and the magnetic separator 5, the treatment of incinerated ash is simplified.

Example 4
FIG. 7 shows a fourth embodiment, which is the same as the second embodiment shown in FIGS. 4 and 5 except for points that are particularly pointed out. In the fourth embodiment, bottom ash containing less foreign matter does not need to be processed by the roll screen 2, the crusher 3, and the magnetic separator 5, so the disposal of the incinerated ash is simpler than in the second embodiment.

1 Receiving hopper 2 Roll screen 3 Impact crusher 4, 5 Magnetic separator 6 Sieve 7 Silo 8, 9 Net cage 10, 11 Water tank 12 Dioxin removal device 13 Wet pulverizer 14 Desalination tank 15 Solid-liquid separation device 16 Wastewater treatment device 20 Rolls 21, 22 Flange 24 Roll shaft 25 Opening

Claims (6)

A roll screen step in which main ash from a garbage incinerator is treated with a roll screen and separated into an under-screen component that has fallen below the roll screen and an on-screen component that has passed above the roll screen;
a first magnetic separation step of separately magnetically treating the under-screen component and the on-screen component to sort out the magnetic substances;
By performing a sieving step of sieving the under-screen component and the on-screen component after sorting the magnetic substances into non-magnetic foreign matter and ash,
A method for treating incinerated refuse ash, wherein the incinerated refuse ash is separated into magnetic substances, non-magnetic foreign matter, and ash. 2. The method of treating incinerated ash according to claim 1, wherein the crushing step of crushing the screened components by an impact crusher is performed between the roll screen step and the first magnetic separation step. If the amount of foreign matter in the main ash is large, perform the roll screen step,
When the amount of foreign substances in the main ash is small, the roll screen step is omitted, and a second magnetic separation step is performed to treat the main ash with a magnetic force and sort out magnetic substances. Or the disposal method of garbage incineration ash of 2. 4. The method for treating incinerated ash according to any one of claims 1 to 3, wherein in said first magnetic separation step, the under-screen component and the on-screen component are treated by separate magnetic separators. a wet step in which water is added to treat at least a portion of the sieved ash from the sieving step;
Further performing a water washing step of storing the magnetic substance and the foreign matter in separate water-permeable baskets and washing them with water,
5. The method for treating refuse incineration ash according to any one of claims 1 to 4, wherein at least part of the wastewater generated in said water washing step is used in said wet step. a roll screen for treating bottom ash from a garbage incinerator;
A magnetic separation device that separates the under-screen component and the on-screen component that have fallen to the lower side of the roll screen by magnetic force and sorts the magnetic substances,
A sieve for sieving the under-screen component and the on-screen component after sorting the magnetic substances into non-magnetic foreign matter and ash,
A refuse incineration ash treatment system configured to separate refuse incineration ash into magnetized matter, non-magnetized foreign matter, and ash.

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