JP2000024618A - Treatment of incineration ash - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an incineration ash treating method capable of simply and efficiently treating and efficiently utilizing the incineration ash. SOLUTION: This treating method comprises the steps of pyrolyzing an unburnt organic material in the incinerating ash 1; granulating the incineration ash 1 into <=150 μm to accelerate the chemical reaction of a harmful crystalline compound such as dioxin; heating the granulated incineration ash under a oxygen poor atmosphere at 350-550 deg.C and quenching the heated incineration ash to <=200 deg.C; and mixing a sulfide suitable to prevent the elution of heavy metal compounds in the incineration ash passed through the steps in an atmosphere of 40-150 deg.C.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a technology for treating incinerated ash generated during incineration of, for example, municipal waste, sewage sludge, and other industrial wastes. The present invention relates to a method for treating incineration ash that can easily and efficiently treat incineration ash (including “main ash” and “fly ash”) and effectively use the same.

[0002]

2. Description of the Related Art Conventionally, incineration ash generated during incineration of municipal garbage, sewage sludge, and other industrial wastes is partially replaced with cement filler or aggregates such as blocks, and furthermore, with incineration ash. After being melted, it has been used as a roadbed material or the like, but most of it has been landfilled.

[0003]

However, in recent years,
It is becoming difficult to secure landfills, and incinerated ash
Usually, it contains dioxins such as dioxins and dibenzofurans and heavy metals such as chromium, mercury, lead, and cadmium, and disposal standards are strict from the viewpoint of water pollution by such dioxins and heavy metals. Cost-managed landfills are required,
There is a problem that it is difficult to use. Therefore,
Today, the safety treatment of the incinerated ash is a very important issue.

[0004] By performing incineration ash safety treatment,
This can be used as an auxiliary material for cement. However, incinerated ash contains CaO, SiO ₂ , Al ₂ O ₃ , Fe ₂
Although it contains a lot of active ingredients of cement such as O ₃ ,
On the other hand, it contains a large amount of alkali components such as K ₂ O and Na ₂ O and chlorine components such as Cl, and it is not preferable to use this as it is as a cement material. Even if it is going to treat incineration ash as it is with the latest baking equipment, not only the above-mentioned alkali component and chlorine component adhere to a heater and a sensor, etc., but also it becomes impossible to perform a stable operation, such as blocking, Incinerated ash causes alkali-aggregate reaction, corrosion of reinforcing steel due to chlorine, and the like, and there is a problem in directly using it as a cement auxiliary material. Furthermore, incinerated ash contains a large amount of unburned organic matter and heavy metal compounds, and even if an attempt is made to adopt the cement solidification method, which is an appropriate treatment method, methane gas is generated from the unburned organic matter in a short time and the solidified matter is destroyed. In addition, harmful heavy metals elute from the damaged part, and there is a problem in maintaining the environment.

[0005] In general, currently operating incinerators emit a small amount of incinerated ash completely burned, contain a large amount of unburned organic matter, and even when solidified as cement, etc., may cause methane gas and the like. Significantly accelerates environmental pollution. Even if dioxins and other chlorine and alkali components are contained in the incinerated ash, even if they are solidified with cement as they are, the solidification will be damaged by alkali-aggregate reaction etc. in a short time, resulting in functional damage. It is thought that it is connected. Cadmium (Cd) in incineration ash
Also, heavy metals such as lead (Pd) dissolve in activated state in rainwater even when solidified with cement, and cannot be used or discarded as it is.

It is known that dioxins float when left in an atmosphere of about 600 ° C. or higher while being ionized by carbon, oxygen, chlorine and the like of the constituent elements. The component elements in this state have not been evaluated as dangerous substances. However, it is known that when gradually cooled, it is regenerated and becomes highly toxic.

Further, among heavy metals, elements mainly collected in the sulfide phase on the earth, such as copper, silver, zinc, cadmium, mercury,
Lead and arsenic are considered harmful among heavy metals,
In nature, it is a principle that it exists stably as a sulfide. For example, zinc exists as a sphalerite with the compound ZnS as a natural ore, mercury with cinnabar as a compound ore with HgS as a natural ore, copper with a compound chalcopyrite with a compound Cu ₂ S, and lead with a compound PbS as a galena. However, the elements that collect in the sulfide phase in the incineration ash are artificially processed by incineration or the like, and are therefore compounds of other elements.

SUMMARY OF THE INVENTION In view of the above problems, the present invention has been made to solve the problems, and the object thereof is to include incinerated ash (including "main ash" and "fly ash"). ) Removes unburned organic matter, which is a source of methane, and decomposes and stabilizes dioxins.
Converted into sulfides that exist in nature to suppress the solubility of various heavy metal substances and converted into sulfides that are stable in nature.
It is an object of the present invention to provide a method for treating incinerated ash that can easily and efficiently treat incinerated ash at a relatively low temperature of up to 550 ° C. and make effective use of it.

[Means for Solving the Problems]

In order to achieve the above object, a method for treating incinerated ash according to the first aspect of the present invention includes a step 1 for thermally decomposing unburned organic matter in the incinerated ash, and a chemical reaction of harmful crystalline compounds such as dioxins. The incinerated ash intended to promote 1
Step 2 of forming particles into 50 μm or less, heating the incinerated ash to 350 ° C. to 550 ° C. in a low-oxygen atmosphere and rapidly cooling the heated incinerated ash to 200 ° C. or less. Mixing the sulfide which is optimal for preventing the heavy metal compound from being dissolved out of the incinerated ash after the process in an atmosphere at 40 ° C to 150 ° C. In a preferred embodiment, the incineration ash is mixed with lime in a low oxygen atmosphere of the incineration ash treatment method (claim 2). Nitrogen gas or hydrogen is used to create a low oxygen atmosphere in the incineration ash treatment method. Means formed by supplying gas (Claim 3), Means for charging incineration ash combustion gas or fuel combustion exhaust gas and carbon dioxide gas into the sulfide reaction environment of heavy metals contained in the incineration ash (Claim 4) ). Here, the incinerated ash includes “main ash” and “fly ash”.

That is, the method for treating incinerated ash according to the present invention comprises a step of thermally decomposing unburned organic matter in the incinerated ash, a step of granulating the incinerated ash to promote a reaction in the next step, Reducing the dioxins contained in the incinerated ash in a reducing atmosphere, and further comprising the step of converting harmful substances into sulfides (claim 1), wherein the chlorine component of the dioxins is Ca Reacting with the components to form a stabilizing component (claim 2); using nitrogen gas or hydrogen gas to create a stable atmosphere for accelerating ionization of dioxins (claim 3); In order to accelerate sulfide generation for preventing elution, incineration ash combustion gas and fuel combustion exhaust gas are used (claim 4).

[0011]

By heating the incinerated ash, organic substances and dioxins which are methane sources are decomposed into carbon, oxygen, carbon dioxide, chlorine and activated. Among them, the chlorine component is combined with sodium (eg, Na, Ca, Kl, etc.), fixed as a stabilizing substance (eg, CaCl, etc.), and then quenched to prevent re-generation of dioxins. The sulfide reacts with the contained heavy metal oxides, and natural ores existing in nature (for example, mercury is cinnabar,
Cadmium is converted to cadmium sulfide ore, etc. to prevent elution of heavy metals, and incinerated ash is used as a cement auxiliary material.

[0012]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the present invention will be described more specifically based on embodiments of the invention shown in the drawings. Here, FIG. 1 is a flowchart. In the figure, the incineration ash (“main ash” and “fly ash”) discharged from the garbage incineration plant
1) is sent to the reaction tank A2, where organic substances and harmful substances such as dioxins in the incineration ash are thermally decomposed by the heater A4. The solid content and the gas component of the heated incineration ash are stirred by the stirrer A3, and the unburned organic matter is oxidized and removed. Dust containing dioxins is separated from gas components by a filter 5 in the discharged exhaust gas. The form of the reaction tank A2, the heater A4 and the stirrer A3 is not limited to this mode, and it is also possible to use a device having the functions of these three devices, for example, a rotary kiln.

The incinerated ash that has passed through the process of the reaction tank A2 is converted into particles having a size of 150 mesh or less by a granulating device 6, for example, a rotary crusher or a mill. This is an auxiliary means for enlarging the surface area of the incinerated ash in the next reaction step and assisting in promoting the reaction. In this embodiment, in order to be able to treat 100 kg of incinerated ash in the next step within a time of about 2 minutes, the dioxins contained in the incinerated ash are converted to N.O. D. It was evaluated that it could be reduced to about 0.05 ng / g TEQ.

The incinerated ash that has been granulated is discharged from the granulator 6 and sent to the reaction tank B9. In addition, with lime 7,
Lime is supplied to the reaction tank B9. In this lime, quick lime, slaked lime and the like all have the same effect. Furthermore, as a material for constructing a low oxygen environment, the reaction tank B9
Actively create nitrogen gas and deoxygenation in the interior
H ₂ gas was added each supplied from the gas supply unit 8, the heater B10 and heated at a relatively low temperature of 350 ° C. ~ 550 ° C., is mixed and stirred by a stirrer B11. In this reaction tank B9, by adding an oxygen concentration of 3% or less and a Ca component weight ratio of 3 to 5%, the treatment of dioxins contained in the incineration ash discharged from the garbage incineration plant can be almost eliminated. confirmed.

The incinerated ash treated in the reaction tank B9 is cooled by the cooling device 12 so that the decomposed dioxin is not regenerated.
It is quenched to below ℃ and sent to the reaction tank C15. In particular, among heavy metals, zinc, mercury, cadmium, copper, lead, etc., which are supposed to accumulate and cause damage in the human body, exist as sulfides in nature, are extremely stabilized, and are hard to elute. It has been known. In view of this phenomenon, for example, sulfur is added to the sent reaction tank C15 using the sulfide 13 as an adjusting agent. Furthermore, this incinerated ash has a strong alkaline component, and in order to carry out the safe treatment aimed at in the present invention, it is necessary to make the incinerated ash with a pH that hardly dissolves heavy metals as much as possible. Ideally, lead (Pb) should have a pH of 9 and cadmium (Cd) should have a pH of 7.5, but it is realistic to focus on lead (Pb) which is contained in the largest amount in incinerated ash. It is. The combustion exhaust gas passing through the filter 5 and the regulating gas 14, for example, carbon dioxide gas are added to the reaction tank C15,
The mixture is heated to 40 ° C. to 150 ° C. by a heater C16 and mixed and stirred by a stirrer C17 to adjust the pH. In this embodiment, the pH becomes about 10 by introducing 1% of sulfur incineration ash, 2 m ³ / hr of combustion exhaust gas, and 2 liters of carbon dioxide gas, so that the solubility of lead (Pb) becomes extremely small, and In the metal dissolution test of Pb, Cd, Cr and As, 0.001 mg /
It could not be detected in less than 1 liter.

The incinerated ash treated in the reaction tank C15 is discharged as a cement auxiliary material 18. Since the treated incinerated ash has been calcined by passing through these steps, it causes a hydration reaction when mixed and stirred with an appropriate amount of water,
Can be solidified.

[0017]

As is apparent from the above description, according to the method for treating incinerated ash according to the present invention, incinerated ash ("main ash") is used.
And "fly ash") can be treated at a relatively low temperature of 350 ° C to 550 ° C. There is no need to treat at a high temperature of 1000 ° C or more, and incineration ash (“main ash” and “fly ash”) is extremely effective. "), Which can be treated with cement supplements,
It can be effectively used as a raw material. This has been explained mainly for general incinerated ash, but "fly ash" in incinerated ash designated as specially managed waste can also be treated in the same way, and there is no pollution problem .

[Brief description of the drawings]

FIG. 1 is a flowchart showing an embodiment of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Incineration ash 2 Reaction tank A 3 Stirrer A 4 Heater A 5 Filter 6 Particle generator 7 Lime 8 Gas supply device 9 Reaction tank B 10 Heater B 11 Stirrer B 12 Cooling device 13 Sulfide 14 Adjustment gas 15 Reaction tank C 16 Heater C 17 Stirrer C 18 Cement auxiliary material

 ────────────────────────────────────────────────── ─── Continuing from the front page (72) Inventor Hiroyuki Ito 6-17 Kajiyacho, Nagasaki City Heights Kadiya 601 (72) Inventor Katsuyuki Ogawa 139-3-501 F-term, Takada-go, Nagayo-cho, Nishisonogi-gun, Nagasaki Reference) 3K061 NA01 NA02 NA07 NA09 NA11

Claims (4)

[Claims] 1. A step 1 for thermally decomposing unburned organic substances in incinerated ash, and a step 2 for converting the incinerated ash to 150 μm or less for the purpose of promoting a chemical reaction of harmful crystal compounds such as dioxins. Heating the incinerated ash to 350 ° C. to 550 ° C. in a low-oxygen atmosphere and rapidly cooling the heated incinerated ash to 200 ° C. or less; and heavy metal compounds of the incinerated ash having passed through this step. Sulfide at 40 ° C, best for preventing elution of sulfide
A step 4 of mixing in an atmosphere at a temperature of 150 ° C. to 150 ° C. 2. The method for treating incinerated ash according to claim 1, wherein lime is mixed with the incinerated ash in a low oxygen atmosphere in the method for treating incinerated ash. 3. The incineration ash treatment method according to claim 1, wherein the incineration ash treatment method is formed by supplying a nitrogen gas or a hydrogen gas to create a low oxygen atmosphere. . 4. The method for treating incinerated ash according to claim 1, wherein incinerated ash combustion gas or fuel combustion exhaust gas and carbon dioxide gas are introduced into a sulfide reaction environment of heavy metals contained in said incinerated ash. .