JPH09248419A - Waste gas treatment method for ash melting furnace and apparatus therefor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To actualize recovery and recycling of molten fly ash contained in a waste gas discharged out of an ash melting furnace and at the same time easily carry out disposal of components which can not be used for recycling. SOLUTION: A waste gas 11 discharged out of an ash melting furnace 2 is primarily cooled by a primary cooling apparatus 5, so that only high boiling point substances in the waste gas 11 are separated by solidification separation and then high boiling point substances 11, separated from the primarily cooled gas 11a by solidification separation are recovered by a ceramic filter 5b. Moreover, a waste gas 11b which passes through the ceramic filter 5b is secondarily cooled by a secondary cooling apparatus 6a, so that volatile heavy metals in the waste gas 11b are separated by solidification separation and then heavy metals 112 separated from the secondarily cooled gas 11c by solidification separation are recovered by a bag filter 6b. In this way, the high boiling point substances 111 and the heavy metals 112 contained in the waste gas are separated and recovered.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to ash obtained by incinerating municipal waste, industrial waste, and other waste (soot dust separated and recovered from incineration residue discharged from a refuse incinerator and its exhaust gas). The present invention relates to a method for treating exhaust gas discharged from an ash melting furnace when melted in the ash melting furnace, and an apparatus for carrying out the method.

[0002]

2. Description of the Related Art Since waste such as municipal waste and industrial waste is incinerated to be reduced in volume, volume, and rendered harmless, traditional methods of treating waste include stoker furnaces and fluidized beds. The mainstream of this is incineration using a refuse incinerator such as a furnace.

Thus, the ash obtained by incinerating the refuse is a non-combustible substance such as metal, glass, earth and sand contained in the refuse to be incinerated, or a trace amount of carbon component which cannot be completely burned by combustion. And the incineration residue discharged from the incineration residue port of the incinerator (for example, bottom ash or main ash discharged from the end of the stoker in the stoker) and the exhaust from the incinerator together with the exhaust gas. It is roughly divided into soot dust (fly ash) that is separated and removed from exhaust gas by bag filters, electrostatic precipitators, etc. The proportion of these ash to incinerator is generally incinerated. About 10 to 15 wt% for residues and about 2 to 5 wt% for soot and dust
Therefore, the amount of waste will be greatly reduced and the volume will be reduced by incineration. Moreover, unlike trash, these ashes have no problem in hygiene. For these reasons, ash has traditionally been disposed of in landfills.

By the way, regarding ash, especially soot dust,
It has been pointed out that since its particle size is extremely small, it scatters in landfills, and because it contains harmful substances such as heavy metals, it may elute in rainwater and cause secondary pollution. In general, instead of landfilling soot and dust as it is, it is normal to landfill it after performing some kind of toxic substance elution prevention treatment (for example, solidification treatment with cement or elution prevention treatment with a chelating agent). is there. On the other hand, although waste is reduced in volume and volume by incineration, due to the recent difficulty in securing landfill, further weight reduction and volume reduction and long-term stabilization as waste are required. Moreover, there is a growing social demand for the reuse of ash as valuable resources without discarding it.

Therefore, recently, ash is melted and the molten metal (slag molten metal) is granulated into slag and finally disposed of (landfill or reused as valuables). There is. That is, ash is melted in a melting furnace using fossil fuel or electric power, and the molten metal discharged from the melting furnace is rapidly cooled by being put into water to form granular granulated slag. By such a melting treatment, the volume of ash which is the material to be melted can be reduced to 30 to 40%, and the volume of original waste can be reduced to 3 to 5%. . Moreover, by converting to granulated slag, harmful substances such as heavy metals contained in the ash are encapsulated in a more physically and chemically stable form. Since it is harmless and harmless, it can be disposed of in landfill as it is without performing the above-mentioned treatment for preventing the elution of harmful substances. Further, since the granulated slag has a high hardness, it can be reused as a valuable material such as concrete filler, roadbed material, embankment material, landfill material, and blocks.

As described above, the melting treatment of the ash such as soot and dust discharged and collected from the refuse incinerator is an extremely effective means for reducing the weight, reducing the volume, detoxifying and reusing the waste. , Is expected to solve the problems that have been pointed out in the waste management.

By the way, as the ash melting furnace, there have been conventionally used various systems (for example, surface system, swirl flow system, coke bed system, arc system, plasma system, electric resistance system, induction heating system, etc.). Although it has been developed and put into practical use, it is impossible to slag all the ash in any of the methods. That is, the ash charged into the ash melting furnace has a melting point or higher (usually 1300
It is heated to ~ 1500 ° C) and melted, but since the ash is melted at such a high temperature, all the ash does not completely slag, and a part of the ash component is volatilized and melted. It becomes fly ash and is discharged outside the furnace together with the exhaust gas. Particularly, heavy metals having a low melting point among the ash components are volatilized in a considerable amount and are transferred to the exhaust gas. This is clear from Table 1 described later, and the content ratio of heavy metals (Zn, Pb) in the molten fly ash is higher than that in the molten metal.

In this way, the exhaust gas discharged from the ash melting furnace contains the original gas components (N ₂ gas and CO ₂ , CO,
In addition to O ₂ etc.), most of the ash components are contained as a gas phase having a boiling point or higher, a volatilized gas body, and a sublimation gas body.

For this reason, conventionally, the exhaust gas is generally cooled to an appropriate temperature, the molten fly ash in the exhaust gas is collected and removed by a bag filter, and then released to the atmosphere. Is normal. That is, high temperature exhaust gas discharged from the ash melting furnace (usually 1000 to 12
The temperature (generally, 2 ° C.) that the filter material of the bag filter (composed of polytetrafluoroethylene cloth, glass cloth, etc.) can withstand 100 ° C. by air cooling or water cooling.
When cooled to about 00 ° C.), the heavy metals, other salts, and oxides that have been volatilized in the exhaust gas at high temperature become solids in the form of fine powder. Therefore, by reducing the temperature of the exhaust gas to about 200 ° C., it is possible to solidify all the molten fly ash components contained in the exhaust gas as a gas phase, a volatilized gas body, and a sublimated gas body into a fine powdery solid. By guiding the exhaust gas thus cooled to the bag filter, it is possible to reliably collect and remove the molten fly ash contained in the exhaust gas and recover it from the bag filter.

By the way, Table 1 shows that the ash to be melted, which is soot dust separated and collected from the exhaust gas generated during the incineration of municipal waste, is melted in an electric resistance type ash melting furnace and is discharged from this ash melting furnace. When the molten fly ash is collected and collected by the bag filter after reducing the temperature of the exhaust gas to about 200 ° C, in the molten ash (soot dust), molten metal, and molten fly ash (collected and collected by the bag filter) Although the content ratios of the main components are shown, as is clear from Table 1, the components that account for a large proportion of the molten fly ash components are alkali metals such as K and Na and alkalis represented by Ca. earth metal and Zn, and a and heavy metals such as Pb, these alkaline earth metals and heavy metals, Cl which also accounts for a large proportion in the molten fly ash ^-, bonded to SO ₄ ^2-like , Salt or acid It is considered that exists as a thing. That is, the molten fly ash component is an alkali metal salt,
First consisting of oxides and salts of alkaline earth metals, oxides
It is roughly divided into a component group and a second component group consisting of salts and oxides of heavy metals. And, as the salt, Cl
^- as seen from the many cases, it is considered overwhelmingly things chloride in many cases. The components such as the molten fly ash and the ratio thereof vary depending on the components of the waste and the type of the refuse incinerator or the ash melting furnace, but are generally as shown in Table 1, and the molten ash subjected to the melting treatment The amount of molten fly ash (collected and collected from the exhaust gas generated during the melting process of the molten ash) is generally 3 to 10% regardless of the type of the ash melting furnace.
It is a degree.

[0011]

[Table 1]

Although the molten fly ash contained in the exhaust gas is only about 3 to 10% of the ash to be melted (soot dust) as described above, it is a valuable metal resource which is said to have a short useful life. Heavy metals are contained in large amounts (for example, Zn, Pb, which are especially contained in large amounts, according to the Mining Handbook, 1994 edition, as of 1992, the number of years of harvest (world reserves 47 years (Z)
n), it has been pointed out that it is only 24 years (Pb)), so it is preferable to recycle the second component group (heavy metals) of the molten fly ash components, and the request is extremely high.

[0013]

However, depending on the above-mentioned conventional exhaust gas treatment method, the molten fly ash collected by the bag filter is mixed with the first component group and the second component group which is required to be recycled. The ratio (content ratio) of the second component group in the recovered molten fly ash is extremely low. For example, as shown in Table 1,
The content ratio of Zn in the molten fly ash was only 8.2%,
The Pb content is only 6.4%. Therefore, it is economically unprofitable to effectively reuse low-concentration heavy metals as valuables from such molten fly ash, and it is practically impossible to recover and recycle the molten fly ash. It was

For this reason, in the conventional art, the recycling of the molten fly ash has to be abandoned, and the actual situation is that it must be landfilled. Of course, there is a problem in performing such disposal. That is, since the molten fly ash has a low content ratio as described above, it contains a large amount of harmful substances (heavy metals), and therefore cannot be directly landfilled. It is necessary to take some safety measures such as taking measures to prevent elution of harmful substances.

As described above, the molten fly ash obtained by the conventional exhaust gas treatment method has a problem regardless of whether it is recycled or disposed of in a landfill, and its solution is strongly desired.

The present invention has been made in view of the above points, and an exhaust gas treating method capable of treating exhaust gas discharged from an ash melting furnace without causing the above-mentioned problems and a method therefor are suitable. It is an object of the present invention to provide an exhaust gas treatment device that can be implemented, thereby realizing the recovery and recycling of the molten fly ash contained in the exhaust gas and the easy disposal of the components that cannot be recycled.

[0017]

By the way, the molten fly ash contained in the exhaust gas discharged from the ash melting furnace is composed of various components as described above, but these component characteristics are different, Each has its own melting point, boiling point, sublimation temperature, and vapor pressure. On the other hand, many of the components constituting the molten fly ash, as described above, Cl ^- has many present as chloride bound to, chlorides of the first component group, namely (KC
1, NaCl, CaCl _2, etc.) have a higher boiling point and a lower vapor pressure than chlorides (PbCl ₂ , ZnCl ₂ , etc.) of the second component group. Therefore, when the temperature of the exhaust gas is decreased from the temperature (1000 to 1200 ° C.) immediately after being discharged from the ash melting furnace, the chloride of the first component group is changed to the solid phase along with this, and When the temperature is reduced to a certain level (hereinafter referred to as "first component group solidification temperature"),
The chlorides of the first component group are almost completely immobilized.
On the other hand, the chlorides of the second component group have a low boiling point and a high vapor pressure, and therefore, even when the exhaust gas is cooled to the solidification temperature of the first component group, most of it is solidified. Instead, it remains in the gas phase and is solidified while the temperature is reduced from the first component group solidification temperature to a temperature close to the temperature (about 200 ° C.) that the bag filter can withstand as described at the beginning. . As described above, the high-boiling substance that is the first component group and the volatile heavy metals that are the second component group have distinctly different temperature conditions for solidifying by reducing the temperature (cooling) of the exhaust gas.

In the method of treating exhaust gas in an ash melting furnace of the present invention, paying attention to this point, the exhaust gas discharged from the ash melting furnace is primarily cooled to solidify and separate only the high boiling point substances in the exhaust gas. In addition, by further secondary cooling of the primary-cooled exhaust gas and solidifying and separating the volatile heavy metals in the exhaust gas, we propose that the high-boiling substances and heavy metals in the exhaust gas can be separated and collected. To do.

That is, only the molten fly ash component constituting the first component group is solidified by primary cooling, and this is collected and collected. The primary recovery product contains almost no heavy metals of the second component group. Then, by further secondary cooling the exhaust gas from which the primary recovery product has been removed, the second component group remaining in the exhaust gas in the vapor phase is solidified, and this is collected and recovered. Since this secondary recovery product is collected and separated from the exhaust gas from which the first component group has been removed, it naturally contains almost no substance of the first component group and does not contain Zn, Pb, etc. Heavy metals will be contained in high concentration. Therefore, the recycling of the secondary recovery material containing high-concentration heavy metals becomes economically well-profitable and can be realized. On the other hand, since the primary recovery product contains almost no harmful heavy metals, it is possible to simply dispose of it as it is without landfilling, such as solidification with cement, to prevent elution of harmful substances. .

Further, the exhaust gas treating apparatus in the ash melting furnace of the present invention has been devised so that such a method can be suitably carried out, and the primary treating apparatus and its downstream side are provided in the exhaust gas discharge passage of the ash melting furnace. It is provided with the arranged secondary processing device. Thus, the primary treatment device is capable of primary cooling the exhaust gas discharged from the ash melting furnace in order to solidify and separate only the high boiling point substances contained therein, and to recover the solidified high boiling point substances, The secondary treatment device is capable of secondarily cooling the primary cooled exhaust gas so as to solidify and separate the volatile heavy metals contained therein, and recover the solidified heavy metals.

[0021]

FIG. 1 is a block diagram showing an embodiment of the present invention.
This will be specifically described based on the following.

First, the structure of the exhaust gas treating apparatus according to the present invention will be described.

As shown in FIG. 1, the exhaust gas treatment apparatus 1 includes a primary treatment device 5, a secondary treatment device 6, and a final treatment device 7 in an exhaust gas discharge passage 4 extending from an exhaust port of an ash melting furnace 2 to a chimney 3. It is arranged in series.

The ash melting furnace 2 is soot dust (fly ash) collected or collected from incineration residue or exhaust gas discharged from a refuse incinerator (not shown), or ash (melted ash) 9 thereof. Is 1300 to 15 which is a temperature above its melting point.
The molten metal 10 is melted by heating it to 00 ° C., and the molten metal 10 is taken out from the outlet of the furnace 2, and the exhaust gas 11 generated in the furnace 2 by the melting process is discharged to the exhaust gas discharge passage 4. Has become. As the ash melting furnace 2, various types as described at the beginning are used, but in this example, an electric resistance type is used.

By the way, the amount of the exhaust gas 11 generated in the electric resistance type ash melting furnace 2 is usually about 120 Nm ³ (per 1 t of molten ash). The molten ash 9 to be melted in this example is soot dust, and its main components and their content ratios are as shown in Table 1. Further, in the exhaust gas 11 immediately after being discharged from the furnace 2 to the exhaust gas discharge passage 4, since it has a high temperature (1000 to 1200 ° C.),
Most of the contained substances are in the gas phase. That is, exhaust gas 1
The main component of No. 1 is N ₂ gas, but other CO, CO
_{In addition} to containing ₂ , O _{2 and the} like, it also contains ₂ to 10 g (per 1 Nm ^{3 of} exhaust gas) of an ash component which becomes a solid phase at room temperature. Further, needless to say, the molten metal 10 taken out of the furnace 2 is disposed of as described in the beginning, such as being made into granulated slag by being rapidly cooled by being poured into water and being reused as valuable material.

The primary treatment device 5 includes a primary cooler 5a arranged in the exhaust gas discharge passage 4 and a primary filter 5b on the downstream side thereof.
Consists of The primary cooler 5a primarily cools the exhaust gas 11 discharged from the ash melting furnace 2 to a temperature at which only the high-boiling-point substance of the molten fly ash component contained in the exhaust gas 11 can be solidified. Specifically, the exhaust gas 11 introduced into the primary cooler 5a from the furnace 2 through the exhaust gas discharge passage 4 is treated with an alkali metal component (KCl, NaCl, etc.) and an alkaline earth metal component (CaCl _2, etc.). A temperature sufficient to solidify (coagulate), specifically 500 to 750
Air-cooling or water-cooling to ℃ (more preferably 600 to 700 ℃). The primary filter 5b is a solid substance contained in the exhaust gas introduced from the primary cooler 5a, that is, the exhaust gas 11a in which the high boiling point substance is made into a fine powder solid by the primary cooling and is mixed, that is, the alkali metal solidified by the primary cooling. High-boiling substances such as salts are collected and separated, and the primary recovery product 11
It is configured to be collected as ₁ . by the way,
Exhaust gas 1 introduced into the primary filter 5b
Since the temperature of 1a is high as described above, it is necessary to use a structure having excellent heat resistance, and it is possible to use an ordinary bag filter using a filter material made of polytetrafluoroethylene cloth or glass cloth. Can not. In this example, a ceramic filter 5b in which a bag made of ceramic woven cloth or a porous porous cylinder arranged in a shell-and-tube type is used as a filter medium and a fireproof material is lined in a filter casing is used.

The secondary treatment device 6 comprises a secondary cooler 6a and a secondary filter 6b on the downstream side of the secondary cooler 6a, which is disposed in the exhaust gas discharge passage 4 portion on the downstream side of the primary filter 5b. The secondary cooler 6a uses the primary filter 5b to collect the primary recovered material 11
_The exhaust gas 11b from which ₁ (high-boiling substance containing alkali metal and alkaline earth metal as a main component) is separated and removed is secondarily cooled to a general exhaust gas cooling temperature (about 200 ° C.). Specifically, the secondary cooler 6a includes the primary filter 5
The exhaust gas 11b introduced from b is air-cooled or cooled to 180 to 200 ° C., and the volatile heavy metals (PbCl ₂ , ZnC) in the exhaust gas 11b not solidified by the primary cooling are included.
l ₂ etc.) is concentrated and solidified. The secondary filter 6b collects and separates the fine powdery solid substance contained in the exhaust gas 11c introduced from the secondary cooler 6a, that is, the heavy metals 11 ₂ solidified by the secondary cooling, while passing through the exhaust gas 11c. The secondary recovery product 11 ₂ can be recovered. By the way, as the secondary filter 6b, since the temperature of the exhaust gas 11c introduced from the secondary cooler 6a is low as described above, the primary filter 5b
As described above, it is not necessary to take heat resistance into consideration so much, and a normal bag filter or the like in which the filter medium is made of polytetrafluoroethylene cloth, glass cloth or the like can be used. In this example, such a normal bag filter 6b (the filter casing is made of mild steel) is used.

Exhaust gas 11 is treated by the primary treatment device 5
By passing through the secondary treatment device 6 and most of the ash components contained therein, a substantially harmless gas (N
₂ as the main component), but there is a possibility that a trace amount of harmful gas components may still be contained. The final treatment device 7 is a known device provided in consideration of such a point, and detoxifies the exhaust gas 11d that has passed through the secondary filter 6b by an ordinary method to remove harmful gas components remaining in the exhaust gas 11d. It is configured to be completely removed. The exhaust gas 11e that has passed through the final treatment device 7 is discharged from the chimney 3 into the atmosphere.

Thus, the exhaust gas treatment method of the present invention is carried out as follows in the electric resistance type ash melting furnace 2 equipped with the exhaust gas treatment apparatus 1 described above.

That is, when the molten ash (soot dust) 9 whose main component is the content ratio shown in Table 1 is melted in the electric resistance type ash melting furnace 2, the exhaust gas 11 generated in the furnace 2 is generated.
Is discharged to the exhaust gas discharge path 4, and firstly the primary cooler 5a
Will be introduced. And this exhaust gas 11 is the primary cooler 5
It is primarily cooled by a and cooled to 500 to 750 ° C (preferably 600 to 700 ° C). Due to such temperature reduction, most of the high-boiling substances (alkali metal salts and oxides and alkaline earth metal salts and oxides) among the ash components contained in the exhaust gas 11 in the gas phase are solidified. It becomes a fine powdery solid phase. On the other hand, heavy metals (salts and oxides of heavy metals) that volatilize in the exhaust gas 11 have a low boiling point and a high vapor pressure, so that they do not solidify due to such a decrease in temperature, and most of them are in a gas phase state. It remains.

Exhaust gas 11a passing through the primary cooler 5a
Is the ceramic filter 5 that is the primary filter.
While being introduced into b and passing through the filter 5b, fine powdery solid substances mixed in the exhaust gas 11a are collected and separated. The solid substance separated from the exhaust gas 11a is recovered from the ceramic filter 5b. The components contained in the primary recovery product 11 ₁ which is the recovered solid substance are as shown in Table 2.
Almost all of them are occupied by alkali metal components and alkaline earth metal components, and heavy metals are very small. That is, Table 2 shows the content ratios of the main components in the primary recovery product 11 _{1. From} this table, the primary recovery product 1 1
It is understood that 1 ₁ contains almost no heavy metals.

The exhaust gas 11b from which the primary recovery product 11 ₁ has been separated and removed is passed from the ceramic filter 5b to the secondary cooler 6a.
Is secondarily cooled and cooled to 180 to 200 ° C. When the temperature is reduced to such a temperature, the volatile heavy metals that have not been solidified by the primary cooling are almost completely solidified and become a fine powdery solid substance. It should be noted that alkali metal salts other than heavy metals which are not solidified in the primary cooling but remain in the vapor phase state are also solidified in the secondary cooling, but the amount thereof is very small.

Exhaust gas 11c cooled by the secondary cooler 6a
Is introduced into the bag filter 6b which is a secondary filter, and while passing through the filter 6b, fine powdery solid substances mixed in the exhaust gas 11c are collected and separated. The solid substance separated from the exhaust gas 11c is recovered from the bag filter 6b.
Containing component of 1 _2, as shown in Table 2, the majority accounts are heavy metals component, components other than heavy metals is only a very little. That is, Table 2 shows the content ratios of the main components in the secondary recovery product 11 _{2. From} this table, the secondary recovery product 11 ₂ contains almost no components other than heavy metals, and the high concentration of heavy metals is high. It is understood that it is a thing.

As described above, the molten fly ash component contained in the exhaust gas 11 in the gas phase is reduced in temperature in two stages, and the primary recovery product 1 containing a high boiling substance such as an alkali metal salt as a main component is used.
It is separated into 1 ₁ and a secondary recovery product 11 ₂ containing heavy metals as a main component, and recovered separately from the filters 5b and 6b. Therefore, the primary recovery product 11 ₁ containing almost no harmful heavy metals can be safely disposed of as it is (landfill) without the trouble and expense of performing the harmful substance elution prevention treatment as described at the beginning. You can On the other hand, secondary harvest 11 _2, heavy metals can be reused as valuable resources (especially, Zn, Pb) since the contained at a high concentration, which can be effectively used as a mining resources, recovered again Resource recycling is well worth the profit.

[0035]

[Table 2]

The present invention is not limited to the above-described embodiments, but can be appropriately improved and changed without departing from the basic principle of the present invention. For example, as the respective coolers 5a, 6a and the respective filters 5b, 6b, depending on the type of ash melting furnace, the ash 9 to be melt-processed by this, and the components of the molten fly ash contained in the exhaust gas 11, etc. It is possible to arbitrarily use the optimum one for processing. In addition, each cooler 5a, 6a
The exhaust gas cooling temperature due to the above can be appropriately set according to the molten fly ash component, the melting treatment condition, the exhaust gas treatment condition, and the like, but it is generally preferable to set the above temperature.

[0037]

As is apparent from the above description, according to the exhaust gas treating method of the present invention, the molten fly ash contained in the exhaust gas contains the primary recovered substance containing almost no heavy metals and the high concentration of heavy metals. It is possible to separate and collect the secondary recovered matter, and to solve all the problems on the recovery and recycling of waste fly ash and the waste disposal that have been pointed out in the past when melting ash such as incineration residue. You can That is, since the secondary recovered material contains a high concentration of heavy metals such as Zn and Pb, which are valuable metal resources that are said to have a short useful life, the heavy metals contained in the molten fly ash are economically economical. It is possible to effectively recover and recycle as valuable resources without causing any problem (collecting and recycling is not profitable). Since the secondary recovered material of the molten fly ash is reused without being disposed of in this manner, the amount of waste fly ash disposed of is reduced, and as a result, the amount of waste disposed of by incineration of waste and melting of ash is reduced. It will be possible to further reduce the volume and volume of the. On the other hand, the primary recovery product is mainly composed of alkali metals and alkaline earth metals, and contains almost no harmful heavy metals. It can be performed easily and inexpensively without applying.

Thus, the exhaust gas treatment method of the present invention is
It contributes to the global environment improvement such as pollution prevention and recovery of valuable resources, while making the most effective use of the advantages of melting treatment of ash such as dust generated after incineration of garbage, and its practical value is extremely large. It will be.

According to the exhaust gas treating apparatus of the present invention,
The above-mentioned exhaust gas treatment method can be suitably implemented.

[Brief description of drawings]

FIG. 1 is a system diagram showing an example of an exhaust gas treating apparatus in an ash melting furnace according to the present invention.

[Explanation of symbols]

1 ... Exhaust gas treatment device, 2 ... Ash melting furnace, 3 ... Chimney, 4 ... Exhaust gas discharge passage, 5 ... Primary treatment device, 5a ... Primary cooler, 5
b ... Primary filter (ceramic filter), 6 ... Secondary treatment device, 6a ... Secondary cooler, 6b ... Secondary filter (bag filter), 7 ... Final treatment device, 9 ... Ash (molten ash),
10 ... Molten metal, 11, 11a, 11b, 11c, 11d,
11e ... Exhaust gas, 11 ₁ ... Primary recovery product, 11 ₂ ... Secondary recovery product.

Claims (2)

[Claims] 1. Exhaust gas discharged from an ash melting furnace is primarily cooled to solidify and separate only high-boiling substances in the exhaust gas, and primary cooled exhaust gas is further secondary cooled to volatilize in the exhaust gas. A method for treating exhaust gas in an ash melting furnace, characterized in that high-boiling substances and heavy metals in exhaust gas can be separated and collected by solidifying and separating heavy metals. 2. An exhaust gas discharge passage of the ash melting furnace is provided with a primary treatment device and a secondary treatment device disposed downstream thereof.
The primary treatment device is a device that can primarily cool the exhaust gas discharged from the ash melting furnace so as to solidify and separate only the high-boiling-point substances contained therein, and collect the solidified high-boiling-point substances. Is an exhaust gas treatment apparatus in an ash melting furnace, which is capable of recovering the solidified heavy metals by secondarily cooling the primary cooled exhaust gas to solidify and separate the volatile heavy metals contained therein. .