JP2002355638A - Ash heat treatment method - Google Patents

Abstract

(57) [Summary] [PROBLEMS] To efficiently and reliably decompose halogenated aromatic compounds such as dioxins contained in ash such as fly ash and bottom ash generated during incineration of refuse. , To remove. SOLUTION: As incineration ash such as fly ash and furnace bottom ash, as an agent having an oxidation catalytic activity and / or an agent having an oxidation activity,
(A): an oxide of a metal selected from molybdenum (Mo), chromium (Cr), manganese (Mn), cobalt (Co), nickel (Ni), tungsten (W) and vanadium (V); An oxygen-containing iron compound; (c): an oxidizing agent selected from potassium nitrate (KNO ₃ ), sodium nitrate (NaNO ₃ ) and sodium peroxide (Na ₂ O ₂ );
(D): hydrogen peroxide (H ₂ O ₂ ) and ozone (O ₃ )
Oxidizing agent and the like are added, and the mixture is heated to a temperature of 300 ° C. or more in the presence of oxygen and water vapor.
A heat treatment method for ash, characterized in that the ash is cooled to 00 ° C or less.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for heat-treating ash such as fly ash or incinerated ash (furnace ash) generated in a refuse incinerator or the like, and more particularly, to a halogenated aromatic contained in the ash. The present invention relates to a heat treatment method for ash that enables decomposition and removal of group III compounds.

[0002]

2. Description of the Related Art Halogenated aromatic compounds such as dioxins generated during incineration of refuse are taking measures to prevent their diffusion into the environment because of their strong toxicity. For example, at present, a technology has been established to collect about 90% of dioxins contained in combustion gas together with fly ash by providing a special dust filter such as a bag filter in an exhaust gas treatment device of a waste incineration plant. . However, the fly ash collected in this way contains a high concentration of dioxins, so that it is necessary to detoxify it.

As a technique for treating dioxin and the like in fly ash, there is a method in which fly ash from a refuse incineration plant contaminated with a polyhalogenated compound is directly heat-treated at 200 to 550 ° C. in an oxygen-deficient state in a non-through system. (Japanese Patent Publication No. 6-38863). However, this method has poor decomposition efficiency of dioxins, and according to the measurement of the present inventors, requires treatment at 400 ° C. for 1 hour to remove 99% of dioxins contained in fly ash. However, there is a problem that the processing takes too much time.

On the other hand, in Japanese Patent Application Laid-Open No. 11-267507, a special iron compound catalyst having the property of converting carbon monoxide to carbon dioxide under specific conditions is used intermittently in order to suppress the generation of dioxins in incineration of refuse. A method has been proposed in which a combustion chamber or a reburning chamber of an operation type incinerator is directly spray-added and brought into contact with combustion gas. This method is not intended to remove dioxins in fly ash, but to prevent the generation of dioxins due to memory effects when starting up or shutting down an intermittently operating incinerator. Therefore, no consideration is given to the treatment of fly ash collected from the dust collection equipment.

[0005]

As described above, halogenated aromatic compounds such as dioxins contained in ash such as fly ash and furnace bottom ash generated during incineration of refuse and the like can be efficiently removed. There is a demand for a technique for reliably and reliably decomposing and removing, and this is an object of the present invention.

[0006]

According to a first aspect of the present invention, there is provided a method for heat-treating ash, comprising adding an agent having an oxidation catalytic ability and / or an agent having an oxidizing ability to the ash. Then, after heating to a temperature of 300 ° C. or more in the presence of oxygen and water vapor, it is rapidly cooled to 200 ° C. or less. According to this feature, the action of the added agent having an oxidation catalytic ability and / or the agent having an oxidizing ability and the heating in an oxygen atmosphere and in the presence of water vapor allow the halogenated aromatic compound contained in the ash to be reduced. It can be oxidatively decomposed and removed at a high decomposition rate in a short time. Further, the ash after the heat treatment is rapidly cooled, so that the re-synthesis of the halogenated aromatic compound is reliably prevented. Further, since the agent to be added is a powder, liquid or gas, large-scale equipment such as a fixed-bed catalytic reactor is not required to perform the method of the present invention. Therefore, the method of the present invention is a highly practical method that can be implemented even in existing waste incineration facilities and the like simply by providing small-scale auxiliary facilities.

According to a second aspect of the present invention, there is provided a method for heat-treating ash, wherein the chemicals having the catalytic activity for oxidation include the following (a) and (b); (a): molybdenum (Mo), chromium (Cr) Oxides of metals selected from manganese (Mn), cobalt (Co), nickel (Ni), tungsten (W) and vanadium (V); (b): one or two selected from oxygen-containing iron compounds; It is characterized by the above. According to this feature, in addition to obtaining the same effects as the first aspect, the oxidation catalytic activity of the metal oxide and / or the oxygen-containing iron compound and the heating in an oxygen atmosphere allow the halogenated aromatic compound to be heated. Efficient removal is achieved. In addition, since the metal oxide and the oxygen-containing iron compound remaining in the ash after the treatment have little influence on the human body and the environment, the post-treatment is also easy.

According to a third aspect of the present invention, there is provided the ash heat treatment method according to the second aspect, wherein the metal oxide of (a) is molybdenum oxide (MoO ₃ ), dichromium trioxide (Cr ₂ O).
₃ ), manganese monoxide (MnO), manganese dioxide (M
nO ₂ ), dimanganese trioxide (Mn ₂ O ₃ ), cobalt monoxide (CoO), tricobalt tetroxide (Co ₃ O ₄ ),
Nickel oxide (NiO), tungsten trioxide (W
O ₃ ) and one or more metal oxides selected from divanadium pentoxide (V ₂ O ₅ ). According to this feature, the same function and effect as the second aspect can be obtained. In this case, if a powdery metal oxide is used, it is easy to handle and easy to add, and when mixed with ash, the chance of contact with the halogenated aromatic compound is increased, and the metal oxide is used. This is even more advantageous because it is possible to maximize the oxidation catalytic action of the compound. In addition, since these metal oxides generally have some non-stoichiometric property, the above-mentioned general formula M _m O
_n (where m and n each represent an integer) as well as those having a stoichiometric composition deviated by a predetermined amount [for example, a general formula; M _x O _y (where, 0.90
n / m ≦ y / x ≦ 1.10 n / m)] is also included in the scope of the present invention.

According to a fourth aspect of the present invention, there is provided the ash heat treatment method according to the second aspect, wherein the oxygen-containing iron compound of (b) is iron monoxide (FeO) or iron trioxide (Fe ₃ O _4). ),
α-type ferric oxide (α-Fe ₂ O ₃ ), γ-type ferric oxide (γ-Fe ₂ O ₃ ), α-type ferric hydroxide [α-FeO
(OH)], β-type ferric hydroxide [β-FeO (OH)]
And one or more oxygen-containing iron compounds selected from γ-type ferric hydroxide [γ-FeO (OH)]. According to this feature, the same function and effect as the second aspect can be obtained. In this case, when the powdered oxygen-containing iron compound is used, it is easy to handle and easy to add, and by mixing with the ash, the chance of contact with the halogenated aromatic compound is increased, and the oxygen-containing iron compound is increased. This is even more advantageous because it is possible to maximize the oxidation catalytic action of the iron compound. Further, the oxygen-containing iron compound is a general-purpose agent, and is inexpensive and easily available, so that the ash treatment cost can be reduced. Also these oxygen Mototetsu compound, because it has a certain degree of nonstoichiometric the above-mentioned general formula Fe m _{'O n'} (where m ', n' each represent an integer) stoichiometry represented by like Not only a stoichiometric oxygen-containing iron compound but also a compound whose composition is deviated by a predetermined amount [e.g.
_{x ′} O _{y ′} (where 0.90 n ′ / m ′ ≦ y ′ / x ′ ≦
1.10n '/ m')] is also included in the scope of the present invention.

According to a fifth aspect of the present invention, there is provided a method for heat-treating ash according to the first aspect, wherein the oxidizing agent comprises the following (c) and (d); (c): potassium nitrate (KN
An oxidizing agent selected from O ₃ ), sodium nitrate (NaNO ₃ ) and sodium peroxide (Na ₂ O ₂ ); (d):
An oxidizing agent selected from hydrogen peroxide (H ₂ O ₂ ) and ozone (O ₃ ); one or more oxidizing agents selected from the group. According to this feature, in addition to obtaining the same action and effect as in claim 1, the halogenated aromatic compound is efficiently oxidized and decomposed by the oxidizing action of the oxidizing agent and heating in an oxygen atmosphere. Is removed.

[0011]

According to Japanese Patent Publication No. Hei 6-38863, the polyhalogenated compound present in the fly ash can be decomposed by directly heating the fly ash. It is essential that they be performed under deficient conditions, declaring that this is a critical condition. It is pointed out that the reason for this is that heating under oxygen-excess conditions results in regeneration of polychlorinated dibenzodioxin and dibenzofuran (see the same publication, page 4, left column, lines 32 to 42). Therefore, it has been generally accepted that the decomposition treatment of the halogenated aromatic compound by heating the fly ash is performed under a non-oxygen condition or a reducing atmosphere.

In Japanese Patent Application Laid-Open No. 11-267507, while the dioxins in fly ash are decomposed, Japanese Patent Publication No. 6-38863 is referred to, and such fly ash is rendered harmless downstream of the incinerator. It states that constructing facilities is practically impossible because of the huge capital investment required, and disagrees negatively with the feasibility of technology for processing fly ash to remove dioxins. (The same publication,
See paragraph 0012). For this reason, Japanese Unexamined Patent Application Publication No. 11-2675
It is considered that JP-A-07-2007 proposes means for directly charging a special iron compound catalyst into an incinerator to suppress the generation of dioxins itself. However, Japanese Patent Application Laid-Open
According to the technology of -267507, as a result of suppressing the generation of dioxins in an incinerator, it is expected that the amount of dioxins contained in the generated fly ash can be reduced to some extent, but once the dust is collected. Dioxins present in the recovered fly ash cannot be removed.
In addition, oxygen is required for the action of the iron compound catalyst added to the incinerator in Japanese Patent Application Laid-Open No. 11-267507 and the like. In order to decompose and remove the dioxins present in the iron oxide, heating under non-oxygen conditions is essential, so that the iron compound catalyst can hardly exhibit its function.

Under the circumstances described above, the present inventors have repeatedly studied methods for removing halogenated aromatic compounds such as dioxins in ash.
Contrary to the teaching of JP 863, surprisingly, halogenated aromatic compounds can be efficiently decomposed in a short time by heating to a predetermined temperature under the condition that oxygen is present,
It has been found that a higher decomposition rate can be achieved by adding a specific agent to the heat treatment.
The chemicals used in the present invention have a high oxidation catalytic activity or high oxidizing ability, and by adding these to fly ash and heating in the presence of oxygen, an extremely short-time and highly efficient halogenated aromatic compound is used. The decomposition was realized.

[0014]

BEST MODE FOR CARRYING OUT THE INVENTION The heat treatment method of ash according to the present invention comprises adding an agent having an oxidation catalytic activity and / or an agent having an oxidizing activity to ash, and heating the ash at a temperature of 300 ° C. After heating to 200 ° C., it is quickly cooled to 200 ° C. or less.

The ash to be treated is, for example, fly ash or hearth ash generated from incineration facilities for refuse and the like, which contains or may possibly contain halogenated aromatic compounds. . Fly ash is mainly collected from dust collection equipment such as an electric dust collector and a bag filter, and bottom ash is collected from an incinerator. Examples of the halogenated aromatic compound to be decomposed and removed by the method of the present invention include dioxins such as polychlorinated dibenzodioxin (PCDD), polychlorinated dibenzofuran (PCDF), coplanar PCB (Co-PCB), and PCBs. And the like.

Examples of the agent having an oxidation catalytic activity added to ash include molybdenum (Mo), chromium (Cr), manganese (Mn), cobalt (Co), nickel (Ni), tungsten (W), An oxide of a metal such as vanadium (V) (metal oxide) can be used alone or in combination of two or more [hereinafter sometimes referred to as a drug (a)]. More specifically, for example, molybdenum oxide (Mo)
O ₃ ), dichromium trioxide (Cr ₂ O ₃ ), manganese monoxide (MnO), manganese dioxide (MnO ₂ ), dimanganese trioxide (Mn ₂ O ₃ ), cobalt monoxide (CoO),
Tricobalt tetroxide (Co ₃ O ₄ ), nickel oxide (Ni
O), metal oxides such as tungsten trioxide (WO ₃ ) and divanadium pentoxide (V ₂ O ₅ ).

The above metal oxide is preferably used in a powder state. The particle size of the powder is preferably about 0.01 to 10 μm, more preferably 0.1 to 5 μm, in order to facilitate mixing with the ash. When the particle size is in the above range, the ash is easily mixed with the ash and the contact with the ash increases, so that the halogenated aromatic compound contained in the ash can be efficiently decomposed. The specific surface area of metal oxide is preferably in a 1~200m ² / g approximately, and more preferably if 2~150m ² / g. If the specific surface area is in the above range, the contact point with the halogenated aromatic compound contained in the ash becomes large, so that the decomposition efficiency is improved. The metal oxide is preferably added to the ash in a total amount of 0.05% by weight or more, more preferably 0.1 to 5% by weight.

Examples of the agent having an oxidation catalytic activity include iron monoxide (FeO) and triiron tetroxide (Fe).
₃ O ₄ ), α-type ferric oxide (α-Fe ₂ O ₃ ), γ-type ferric oxide (γ-Fe ₂ O ₃ ), α-type ferric hydroxide [α-
FeO (OH)], β-type ferric hydroxide [β-FeO (O
H)] and oxygen-containing iron compounds such as γ-type ferric hydroxide [γ-FeO (OH)] can be used alone or in combination of two or more [hereinafter referred to as drug (b). There is]. In particular, as the drug (b), it is preferable to use α-type ferric oxide (α-Fe ₂ O ₃ ) or a substance that can be converted to α-type ferric oxide by heating in the presence of oxygen. Substances that can be converted to α-type ferric oxide under such conditions include triiron tetroxide, γ-type ferric oxide, α-type ferric hydroxide, β-type ferric hydroxide, and γ-type ferric hydroxide. Ferrous iron and the like.

The oxygen-containing iron compound is preferably used in a powder state. The particle size of the powder is preferably about 0.01 to 10 μm, more preferably 0.1 to 5 μm, in order to facilitate mixing with the ash. When the particle size is within the above range, the ash is easily mixed with the ash, and the chance of contact with the halogenated aromatic compound contained in the ash increases, so that the decomposition can be performed efficiently. Further, the specific surface area of the oxygen-containing iron compound is preferably about 1 to 200 m ² / g, and more preferable result is obtained if the specific surface area is ^{2 to} 150 m ² / g. The iron oxide, α-type ferric oxide, α-type ferric hydroxide, and β-type ferric hydroxide are 3 to 150 m ² / g, and are γ-type ferric oxide and γ-type ferric hydroxide. 30-150m for iron
² / g. In the specific surface area in the above range, the contact point with the halogenated aromatic compound contained in the ash becomes appropriate, so that the decomposition efficiency by the oxidation catalytic action is improved and the halogenated aromatic compound is less likely to be resynthesized. These oxygenated iron compounds are contained in the ash in powder form in a total of 0.1.
It is preferably added in an amount of at least 05% by weight, and more preferably about 0.1 to 3% by weight from the viewpoint of economy (drug cost).

Examples of oxidizing agents include potassium nitrate (KNO ₃ ) and sodium nitrate (Na
An oxidizing agent such as NO ₃ ) and sodium peroxide (Na ₂ O ₂ ) can be used alone or in combination of two or more [hereinafter sometimes referred to as a drug (c)].

These oxidizing agents can be used in the form of powder or liquid, but are preferably in the form of powder. When the oxidizing agent is in a powder state, it is easy to handle and easy to add, and by mixing with the ash, the chance of contact with the halogenated aromatic compound is increased to maximize the oxidizing action of the oxidizing agent. It becomes possible to withdraw. The particle size when used as a powder is preferably about 0.01 to 10 μm, more preferably 0.1 to 5 μm, for the same reason as the above-mentioned drug (a). The chemical (c) is preferably added to the ash in a total amount of about 0.05 to 10% by weight, more preferably 0.1% by weight or more.

Further, the oxidizing agents include, for example, hydrogen peroxide (H ₂ O ₂ ) and / or ozone (O ₂ ).
₃ ) can be used [hereinafter sometimes referred to as drug (d)]. These oxidizing agents can be used in the form of a gas or a liquid such as an aqueous solution. When the oxidizing agent is in a gaseous or liquid state, the addition is easy, and the oxidative decomposition reaction can be promoted by strengthening the oxidizing atmosphere around the ash. The amount added in this case is 1 × 10 ⁻⁷ to 1 × in terms of an oxidizing agent per 1 g of ash.
About 10 ⁻¹ mol is preferable, and 1 × 10 ⁻⁵ to
More preferably, it is about 1 × 10 ⁻³ mol.

The method of adding an agent having an oxidation catalytic ability and / or an agent having an oxidizing ability (hereinafter sometimes simply referred to as “drug”) to ash is as follows. A liquid (aqueous solution, water slurry, etc.) chemicals may be added and mixed. When adding, sufficient stirring should be performed to ensure a contact area between the chemicals and the halogenated aromatic compound in the ash. Is preferred. Further, the phrase “added to ash” in the present invention includes adding a gaseous drug to a heating container (for example, setting a gas atmosphere containing ozone of the drug (d)). Further, as another addition method, for example, upstream (preferably immediately before) of dust collecting equipment such as a cyclone dust collector, a bag filter, and an electric dust collector.
It is also possible to introduce a powder or liquid (aqueous solution, water slurry, etc.) chemical into the flue. In this case, a specific method of introducing the drug is preferably spraying, blowing or the like. In this way, by adding to the flue on the upstream side of the dust collecting facility, the chemical and the fly ash can be captured in the dust collecting facility in a uniformly mixed state. Therefore, in the ash heat treatment performed later, the stirring step as a pretreatment can be advantageously omitted or simplified.

The heating of the ash is performed in the presence of oxygen. The purpose is to promote a reaction in which the halogenated aromatic compound in the ash is oxidatively decomposed by the action of a drug and the aromatic ring is opened by placing the ash under an oxygen atmosphere. The oxygen concentration for promoting the oxidative decomposition reaction of the halogenated aromatic compound can be about 1 to 50% by volume, preferably 5 to 25% by volume.

The drug (c) and the drug (d) themselves are compounds having oxygen in the molecule, and can generate oxygen by heating and supply it to the ash. Therefore, when the chemical (c) or the chemical (d) is added, the ash is automatically placed in the presence of oxygen, so that it may not be necessary to separately introduce oxygen. In addition, by heating in an atmosphere of the chemical (d) in addition to the chemical (a), the chemical (b) having the oxidation catalytic ability, and the chemical (c) having the oxidizing ability,
A stronger oxidizing atmosphere can be created, and the decomposition of the halogenated aromatic compound is further promoted.

In the method of the present invention, heating is performed under the condition that water vapor is present together with oxygen. The presence of water vapor makes it possible to more reliably oxidatively decompose the halogenated aromatic compound. The water vapor concentration in this case is
The range is 0.1 to 80% by volume, and more preferably 5 to 40% by volume. In addition, steam may be supplied separately, or the ash contained in the ash may be used.

The heating temperature is 300 ° C. or higher, for example, preferably about 300 to 600 ° C.
A temperature range of 500 ° C. is more preferable. Here, the upper limit of the heating temperature was set to 600 ° C. (or 500 ° C.)
At this temperature, it is possible to sufficiently decompose the halogenated aromatic compound in a short time, and it is not necessary to raise the temperature further in the ordinary ash treatment, and this is mainly at the upper limit from the viewpoint of energy efficiency. is there. Therefore, it does not prevent performing heating (for example, 900 ° C.) exceeding the above range.

In the present invention, the temperature is set to, for example, 1 second to 5 seconds.
By holding for about a minute, halogenated aromatic compounds such as dioxins can be decomposed at a high rate. 400-50
Even in a temperature range of 0 ° C., at least 95% or more of the halogenated aromatic compound can be decomposed in a short time of 2 minutes or less. Therefore, considering energy efficiency, 4
It is preferable to maintain the temperature of 00 to 500 ° C. for 1 second to 2 minutes. However, when more complete decomposition is performed, a higher temperature or a longer heat treatment may be performed. In addition, the heating step from the start of heating until the temperature is reached is 0.5 0.5
Minutes to 30 minutes, but preferably 3 minutes to 5 minutes, and all steps from heating to cooling are:
It is preferable to set it for about 5 to 15 minutes.

During the heating, it is preferable to stir the fly ash and the chemical. With sufficient stirring during heating, the fly ash and the chemical are mixed, and the chance of contact with oxygen is increased to promote the decomposition of the halogenated aromatic compound, so that the decomposition efficiency of the halogenated aromatic compound can be increased. Because you can.

After keeping the ash at a temperature of 300 ° C. or more for a predetermined time, the treated material containing the ash is quickly cooled to 200 ° C. or less. This is to prevent resynthesis of the decomposed halogenated aromatic compound. For this reason, the shorter the time from the start of cooling until the temperature of the processed material reaches 200 ° C. or less is preferable, but in actual processing, 0.5 to
The temperature can be lowered to 200 ° C. or less in about 4 minutes.

FIG. 1 is a drawing schematically showing an embodiment of an ash heat treatment apparatus 100 which can be suitably used in the method of the present invention. The ash heat treatment apparatus 100 can be installed after a dust collector in an exhaust gas treatment facility, and includes a supply tank 41 for an ash 31 and a heater 1
3 and a water-cooled cooler 21;
The heater 11 employs a rotary kiln system having a rotating retort (inner cylinder) 15. An example of such a rotary kiln type ash heat treatment apparatus is a die obliquer (registered trademark: manufactured by Mitsui Engineering & Shipbuilding Co., Ltd.).

In FIG. 1, the ash 31 is supplied to a supply tank 41.
Are fed by the screw feeder 42 by a predetermined amount, and are fed into the heater 11 together with the air 35 heated by the air heater 51. The chemicals used in the present invention may be added to and mixed with the ash 31 before being charged into the supply tank 41, or the ash 31 upstream of the heater 11 may be mixed.
Can be added by providing an inlet (not shown) on the transfer path of. Further, for gas such as ozone of the medicine (d), air (oxygen) 35
(And steam). Depending on the type of the chemical, an introducing means may be provided in the heater 11 to add the ash just before heating or during the heat treatment in order to avoid an unintended reaction with components in the ash.

The retort 15 in the heater 11 is provided so as to be inclined from the upstream to the downstream in the traveling direction of the processing ash, and the ash 31 rotates in the inclined retort 15 together with the added chemicals. It moves toward the outlet while being stirred. During this time, the ash 31 is efficiently heated by the heater 13 while being in contact with the medicine and oxygen by stirring, and halogenated aromatic compounds such as dioxins are decomposed. The rotation of the retort at this time is
An appropriate rotation speed is selected so that the ash does not stick to the retort 15 by centrifugal force (for example, about 0.5 to 60 rpm, preferably about 3 to 30 rpm).

The heat-treated ash 31 moves to the cooler 21 downstream via the screw feeder 44, and the water-cooled jacket 23 prevents the re-synthesis of dioxins and the like.
It is quenched by the cooling water inside. The treated ash 31 cooled by passing through the inside of the cooler 21 is discharged from the discharge port 43 and subjected to a process such as cement solidification or chemical treatment as necessary, and is finally disposed. The exhaust gas 33 generated in the heater 11 is sent to an incinerator (not shown) after dust is reduced by a dust collector (not shown).

An ash heat treatment apparatus 101 shown in FIG. 3 is an embodiment in which a liquid medicine supply tank 54 and a liquid feed pump 53 are provided in the apparatus shown in FIG. 1, and an ash heat treatment apparatus 102 shown in FIG. In this embodiment, an ozone generator 55 is provided in the apparatus shown in FIG. 1 so that ozone 37 can be supplied. FIG.
Ash heat treatment apparatus 100 'having a mechanism substantially similar to that of FIG.
2 is a drawing more specifically showing the structure of FIG. In the heat treatment apparatus 100 ′ of FIG. 5, four retorts 15 are provided in the heater 11.
Is provided, so that the stirring efficiency and the heating efficiency are good and the processing capacity is high. 3 to 5
Are the same as those in FIG. 1, and the same components are denoted by the same reference numerals and description thereof will be omitted.

FIG. 6 is a view showing an example in which an exhaust gas treatment device 10 and an ash heat treatment device 100 in a refuse incineration facility or the like are connected in series. In this exhaust gas treatment device 10, after the exhaust gas containing fly ash generated in the incinerator 1 is cooled in the water-cooling and cooling tower 2, it is introduced into the dust collection equipment 3 such as a cyclone dust collector, a bag filter, and an electric dust collector. Configuration. The exhaust gas from which fly ash and the like have been removed by the dust collection equipment 3 is subjected to a decomposition treatment of harmful substances such as dioxins in a reaction tower (not shown) as necessary, and is passed through a blower 4 and an exhaust tower 5 to the atmosphere. Will be released. In the exhaust gas treatment device 10 having such a configuration, when the ash 31 collected in the dust collecting facility 3 is treated by the ash heat treatment device 100, as shown in FIG. From the ash 31 in the heat treatment apparatus 100. Of course, it is also possible to mix the ash 31 collected at the stage before introduction into the ash heat treatment apparatus 100 and the chemical.

Further, as shown in FIG. 6 (b), it is also possible to provide a medicine supply means 6 in the flue upstream (preferably immediately before) of the dust collecting facility 3 to supply the medicine. Although fly ash is targeted as the ash 31 in FIG. 6, the bottom ash recovered from the incinerator 1 can be treated according to FIG. 6 (a).

[0038]

The present invention will be described in more detail with reference to the following Examples and Comparative Examples, which do not limit the present invention in any way. Example 1 <Experimental method> Using the ash heat treatment apparatus shown in FIG.
% By weight (commercial grade 1 or special grade reagent in a mortar with a particle size of 10 μm
The mixture was supplied to a retort rotating at 10 rpm in a heater, and heat-treated while stirring. Polychlorinated dibenzoparadioxin (hereinafter referred to as "PCDDs") and polychlorinated dibenzofurans (hereinafter referred to as "PCDFs") in ash before and after heat treatment
About gas chromatography mass spectrometer (GCM
Quantification was performed by the internal standard method using S). The extraction of PCDDs and PCDFs of the ash sample used for the analysis was performed with toluene using a Soxhlet extractor for 24 hours.

The quantification by GCMS is performed using a commercially available reagent.¹³C mark
Quasi-PCDDs / PCDFs mixture ( ¹³C₁₂-2,3,
7,8-TCDD,¹³C₁₂-2,3,7,8-TCD
F,^{1 3}C₁₂-1,2,3,7,8-P5CDD,¹³C
₁₂-1,2,3,4,6,7,8-H6CDD,¹³C₁₂
-1,2,3,4,6,7,8-H7CDF,¹³C₁₂−
1,2,3,4,6,7,8-H7CDD,¹³C₁₂-1,
2,3,4,6,7,8-H7CDF, O8CDD, O8C
DF) tetravalent of the sample according to the chromatographic area of each chlorine valence
Check the actual concentration of each octavalent PCDDs and PCDFs
It was determined by the quantitative method. And in the ash to be treated, PCDDs
In the total concentration of PCDFs and PCDFs before and after heat treatment
Calculated the decomposition removal rate, and evaluated the decomposition performance promotion effect of each drug.
Valued. For comparison, an agent with oxidation catalytic ability was added.
Measurements were also made for those that did not exist.

In addition, MnO ₂ (particle diameter 1
(Pulverized to 0 μm or less), the decomposition removal rates of PCDDs and PCDFs were measured in the same manner as described above when the amount of addition to ash was changed.

<Experimental conditions> Achieved treatment temperature: 400 ° C. Heating time until reaching the treatment temperature: 5 minutes Retention time of the reached treatment temperature: 2 minutes Carrier gas composition: 10 vol% O ₂ , 5 to 15 vol% H
₂ O / balance N ₂ Cooling method: Water cooled cooling reaction tube, less than 4 minutes until reaching 100 ° C. Analysis item: Total concentration of dioxins by chlorine number (PCDD)
s, PCDFs)

<Experimental results> As shown in Table 1, the decomposition and removal rate of dioxins in the ash heated with the addition of the chemical was higher than the decomposition and removal rate (89.0%) without the addition of the chemical. did. Table 2 shows the decomposition and removal rates of MnO ₂ when the addition amount to ash was changed.

[0043]

[Table 1]

[0044]

[Table 2]

Example 2 <Experimental method> α-Fe ₂ listed in Table 3 was used as a drug sample.
O ₃ , FeO, γ-Fe ₂ O ₃ , α-FeO (OH)
Is a commercially available chemical product (purity 95% or more) in a mortar with a particle size of 5μ.
m or less was used. Table 3, set forth the specific surface area measured by N ₂ adsorption method of each sample. In the experiment, a mixture of ash containing dioxins and each powdered drug was heat-treated under the following experimental conditions using a non-stirring type basic test device shown in FIG. 2 which simulated a heat treatment device for ash. The amounts of PCDDs and PCDFs were measured in the same manner as in Example 1. And, in the ash to be treated, PCDDs and PCDs
The decomposition removal rate was calculated from the concentration change before and after the heat treatment in the total concentration of Fs, and the decomposition performance promoting effect of each drug was evaluated.
For comparison, the measurement was also performed for a sample to which no agent having an oxidation catalytic ability was added.

<Experimental conditions> Achieved processing temperature: 450 ° C. Heating time until reaching the processing temperature: 5 minutes Holding time of the reached processing temperature: 2 minutes Carrier gas composition: 10 vol% O ₂ , 5 vol% H ₂ O /
Balance N ₂ Ash sample filling amount: 30 g Drug addition amount: 3% by weight Apparatus: Quartz glass tube heating type tube furnace apparatus (Fig. 2) Cooling method: Water cooling of quartz reaction tube from outside, less than 4 minutes until reaching 100 ° C Analysis items : Total dioxin concentration by chlorine valence (PCDD)
s, PCDFs)

<Experimental results> As shown in Table 3, the decomposition and removal rate of dioxins in the ash heated with the addition of the chemical was improved as compared with the decomposition and removal rate (95.2%) without the addition of the chemical. did.

[0048]

[Table 3]

Example 3 <Experimental method> Commercially available primary or special grade reagents α-Fe ₂ O ₃ , β-FeO (OH), γ-
FeO (OH) and Fe ₃ O ₄ were pulverized to a particle size of 10 μm or less for use. A mixture of ash containing dioxins and a drug at 3% by weight was supplied to a supply tank using the ash heat treatment apparatus of FIG. 1, and the mixture was fed to a retort rotating at 10 rpm in a heater, and heat-treated while stirring. As in Example 1, the PCDDs and PCDFs before and after the heat treatment were G
Quantification was performed by the internal standard method using CMS. Then, the decomposition removal rate was calculated from the concentration change before and after the heat treatment in the total concentration of PCDDs and PCDFs in the ash to be treated, and the decomposition performance promoting effect of each chemical was evaluated. For comparison, the measurement was also performed for a sample to which no agent having an oxidation catalytic ability was added.

For α-Fe ₂ O ₃ (which had been pulverized to a particle size of 10 μm or less), the decomposition removal rates of PCDDs and PCDFs were measured in the same manner as described above when the amount of addition to ash was changed. The heat treatment temperature is 400
C. and the holding time was 2 minutes.

<Experimental conditions> Achieved processing temperature: 400 ° C., 450 ° C., 480 ° C. Heating time until reaching the processing temperature: 5 minutes Holding time of the reached processing temperature: 2 minutes Carrier gas composition: 10 vol% O ₂ , 5 to 15% by volume H
₂ O / balance N ₂ Cooling method: Water cooled cooling reaction tube, less than 4 minutes until reaching 100 ° C. Analysis item: Total concentration of dioxins by chlorine number (PCDD)
s, PCDFs)

<Experimental results> As shown in Table 4, α-
Fe ₂ O ₃ , β-FeO (OH), γ-FeO (O
H), the dioxin decomposition removal rate of the ash heat-treated with the addition of the Fe ₃ O ₄ agent was improved as compared with the decomposition removal ratio without the addition of the agent. Table 5 shows the decomposition removal rates of α-Fe ₂ O ₃ when the amount added to ash was changed.

[0053]

[Table 4]

[0054]

[Table 5]

Example 4 <Experimental method> While 30 kg of ash was treated per hour using the ash heat treatment apparatus shown in FIG. 500 g of the diluted drug from the drug tank of FIG.
The ash containing the dioxins was heat-treated while stirring. The analysis was performed in accordance with Example 1, and the decomposition removal rate was calculated from the change in the total concentration of PCDDs and PCDFs in the ash to be treated before and after the heat treatment, and the effect of promoting the decomposition performance of each chemical was evaluated. For comparison, the measurement was also performed for a sample to which no oxidizing agent was added.

<Experimental conditions> Achieved treatment temperature: 410 ° C. Heating time until reaching the treatment temperature: 5 minutes Retention time of the reached treatment temperature: 2 minutes Carrier gas composition: 10 vol% O ₂ , 10 to 15 vol%
H ₂ O / Balanced N ₂ Cooling method: Water cooled the cooling reaction tube, less than 4 minutes until reaching 100 ° C. Analysis item: Total concentration of dioxins by chlorine valency (PCDD)
s, PCDFs)

<Experimental results> As shown in Table 6, the dioxin decomposition removal rate of ash added with 10 ^-4 mol / g · ash of hydrogen peroxide and heat-treated was as follows. Rate (90.5%).

[0058]

[Table 6]

Example 5 <Experimental method> Using the ash heat treatment apparatus shown in FIG. 4, an ozone mixed atmosphere containing 100 ppm of ozone generated by an atmosphere-excited ozone generator was introduced into a retort system at 10 ⁻⁴ mol / mol.
g and ash, and heat-treated while stirring the ash containing dioxins. The analysis was performed according to Example 1, and the decomposition removal rate was calculated based on the concentration change before and after the heat treatment in the total concentration of PCDDs and PCDFs in the ash to be treated,
The degradation performance promoting effect of the drug was evaluated. For comparison, measurements were also made on a sample to which no oxidizing agent was added.

<Experimental Conditions> Achieved processing temperature: 410 ° C. Heating time until reaching the processing temperature: 5 minutes Holding time of the reached processing temperature: 2 minutes Carrier gas composition: 10 vol% O ₂ , 5 to 15 vol% H
₂ O / balance N ₂ Cooling method: Water cooled cooling reaction tube, less than 4 minutes until reaching 100 ° C. Analysis item: Total concentration of dioxins by chlorine number (PCDD)
s, PCDFs)

<Experimental results> As shown in Table 7, the dioxin decomposition removal rate of the ash added with 10 ^-4 mol / g · ash of ozone and heat-treated was as follows: 90.5%).

[0062]

[Table 7]

[0063]

According to the method of the present invention, the action of the added agent having an oxidation catalytic activity and / or the agent having an oxidizing activity and the heating in an oxygen atmosphere and in the presence of water vapor cause the halogen contained in the ash. The halogenated aromatic compound can be removed at a high decomposition rate in a short time, and the resynthesis of the halogenated aromatic compound is also prevented. Further, the method of the present invention does not require a large-scale facility, and is a highly practical method that can be implemented with a small-scale auxiliary facility even in an existing incineration facility.

[Brief description of the drawings]

FIG. 1 is a diagram illustrating an embodiment of an ash heat treatment apparatus suitable for carrying out the method of the present invention.

FIG. 2 is a view for explaining a tubular furnace test apparatus used in Example 2.

FIG. 3 is a diagram illustrating an embodiment of an ash heat treatment apparatus suitable for carrying out the method of the present invention.

FIG. 4 is a view for explaining an embodiment of an ash heat treatment apparatus suitable for carrying out the method of the present invention.

FIG. 5 is a view for explaining an embodiment of an ash heat treatment apparatus suitable for carrying out the method of the present invention.

FIG. 6 is a diagram illustrating an example of an exhaust gas treatment apparatus and an ash heat treatment apparatus that can carry out the method of the present invention.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 incinerator 2 water-cooling and cooling tower 3 dust-collecting equipment 4 blower 5 exhaust tower 6 chemical supply means 10 exhaust gas treatment device 11 heater 13 heater 15 retort 17 gas introduction unit 21 cooler 23 water cooling jacket 31 ash 33 exhaust gas 35 air 37 ozone 41 supply tank 42 screw feeder 43 discharge port 44 screw feeder 45 exhaust port 51 air heater 52 fan 53 liquid feed pump 54 liquid medicine tank 55 ozone generator 100, 101, 102 ash heat treatment device

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) B01J 23/30 F23J 1/00 A 23/34 B09B 3/00 304G 23/745 ZAB 23/75 B01J 23 / 74 311M 23/755 321M F23J 1/00 301M (72) Inventor Kazuyo Fujisawa No. 1 Yawata Kaigandori, Ichihara-shi, Chiba Prefecture Mitsui Engineering & Shipbuilding Co., Ltd. Chiba Works (72) Inventor Shinyasu Kanda 1 Yawata Kaigan-dori, Ichihara-shi, Chiba Prefecture Address: Mitsui Engineering & Shipbuilding Co., Ltd. Chiba Works Co., Ltd. F term in the Chiba office of the company (reference) 3K061 NA01 NA07 NA18 4D004 AA36 AB06 CA24 CA32 CA36 CC01 CC09 CC11 DA03 DA06 4G069 AA02 BB04A BB04B BB05A BB05B BC54A BC54B BC58A BC58B BC59A BC59B BC60A BC60B BC62A BC62B BC66A BC66B BC67A BC67B BC68A BC68B CA04 CA10 CA19 DA05

Claims (5)

[Claims] 1. An agent having an oxidation catalytic activity and / or an agent having an oxidation activity is added to ash, and heated to a temperature of 300 ° C. or more in the presence of oxygen and water vapor, and then the ash is rapidly added to the ash.
A heat treatment method for ash, characterized in that the ash is cooled to 00 ° C or less. 2. The method according to claim 1, wherein the chemicals having the oxidation catalytic activity include the following (a) and (b); (a): molybdenum (Mo), chromium (Cr), manganese (Mn), cobalt ( An oxide of a metal selected from Co), nickel (Ni), tungsten (W) and vanadium (V); and (b) a heat treatment of ash, which is one or more selected from oxygen-containing iron compounds. Method. 3. The method according to claim 2, wherein the metal oxide (a) is molybdenum oxide (MoO ₃ ), dichromium trioxide (Cr ₂ O ₃ ), manganese monoxide (MnO), or manganese dioxide (MnO ₂ ). ), Dimanganese trioxide (Mn)
₂ O ₃ ), cobalt monoxide (CoO), tricobalt tetroxide (Co ₃ O ₄ ), nickel oxide (NiO), tungsten trioxide (WO ₃ ) and divanadium pentoxide (V ₂
O ₅ ) A method for heat-treating ash, which is one or more metal oxides selected from O ₅ ). 4. The oxygen-containing iron compound according to claim 2, wherein the oxygen-containing iron compound (b) is iron monoxide (FeO), triiron tetroxide (Fe ₃
O ₄ ), α-type ferric oxide (α-Fe ₂ O ₃ ), γ-type ferric oxide (γ-Fe ₂ O ₃ ), α-type ferric hydroxide [α-F
eO (OH)], β-type ferric hydroxide [β-FeO (O
H)] and γ-type ferric hydroxide [γ-FeO (OH)]
A heat treatment method for ash, which is one or more oxygen-containing iron compounds selected from the group consisting of: 5. The method according to claim 1, wherein the oxidizing agents are the following (c) and (d); (c): potassium nitrate (KNO ₃ ), sodium nitrate (NaNO ₃ ) and sodium peroxide (Na ₂ O ₂ )
(D): hydrogen peroxide (H ₂ O ₂ ) and ozone (O ₃ )
An oxidizing agent selected from the group consisting of one or more selected from the group consisting of: