JP4107056B2 - Method and agent for decomposing halogenated organic compounds - Google Patents

Description

【００５２】
表１から明らかなように、何も添加しないで３００℃に加熱した場合（参考例５）には、ごみ焼却炉の飛灰に含有されるダイオキシン類前駆物質から飛灰の触媒作用によりダイオキシン類が生成し、逆に処理物のダイオキシン類含有量が増加した。一方、各種の有機酸類を添加して加熱した場合（参考例１〜４）には、３００℃という低温度でも高効率でダイオキシン類を分解することができた。
【００５３】
実施例１
参考例１で処理したものと同様の焼却炉飛灰に塩化カルシウムの粉末を２０重量％添加混合した模擬試料を調製し、これにギ酸ナトリウムを重量比で５％添加し、参考例１と同様に加熱処理し、ダイオキシン類の分解率を調べた。
【００５４】
結果を塩化カルシウムを添加しない参考例４と比較すると、表２に示すダイオキシン類分解率が得られた。
【００５５】
【表２】

【００５６】
【発明の効果】
以上詳述した通り、本発明のハロゲン化有機化合物の分解方法及び分解剤によれば、ダイオキシン類等のハロゲン化有機化合物で汚染された固体物質からなる被処理物質中のハロゲン化有機化合物を、安全かつ安価に分解して無害化することができる。[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a decomposition method for decomposing and detoxifying a halogenated organic compound in a substance to be treated, which is a solid substance contaminated with a halogenated organic compound, safely and inexpensively, and a decomposing agent therefor.
[0002]
[Prior art]
Conventionally, the following methods have been proposed as methods for decomposing and detoxifying harmful halogenated organic compounds represented by dioxins discharged from waste incineration plants.
[0003]
(1) Method of incineration and oxidative decomposition at high temperature (Proceedings of the 8th Annual Conference of the Waste Science Society, p. 677-679)
(2) A method of dechlorinating by heating in an inert gas atmosphere ("ORGANOHALOGEN COMPOUNDS Vol.27 (1996)" p.147-152)
(3) Method of reductive dechlorination by contacting with sodium metal ("Proceedings of the 7th Annual Meeting of the Waste Science Society" p.954-957)
(4) Dechlorination by heating together with reducing substances such as amine compounds (Japanese Patent No. 3287298)
[0004]
[Patent Document 1]
Japanese Patent No. 3287298 [Non-Patent Document 2]
“Proceedings of the 8th Annual Meeting of the Waste Society” p. 677-679
[Non-Patent Document 3]
"ORGANOHALOGEN COMPOUNDS Vol.27 (1996)"
p. 147-152
[Non-Patent Document 4]
“The 7th Annual Meeting of the Waste Society Research Presentations” p. 954-957
[0005]
[Problems to be solved by the invention]
In the above method (1), heating at a high temperature of 800 ° C. or higher is necessary, and in the case of a solid pollutant contaminated with a halogenated organic compound that is insufficient in calorific value even if its concentration is high, it is a high energy consumption type. This is uneconomical.
[0006]
In the method (2), dioxins are decomposed by heating at about 200 to 550 ° C., but it is more advantageous in terms of energy than the direct combustion method. However, some dioxins are re-synthesized during the cooling process, such as fly ash generated by incineration of municipal waste, requiring additional measures for cooling. Further, with fly ash having a low melting point, a part of the matrix melts during the decomposition reaction of dioxins, making it difficult to operate the reactor stably.
[0007]
In the method (3), treatment at room temperature is possible, but since it is highly reactive and uses dangerous metallic sodium, there is a high risk of ignition and explosion, and strict safety management is required.
[0008]
The method (4) can be processed at a relatively low temperature of 100 to 300 ° C., is effective for low melting point fly ash, and is energetically compared to the methods (1) and (2). Although it is an inexpensive treatment method, there is a problem in that the mixed chemicals volatilize or decompose to generate malodor or generate a tar component, which requires a post-treatment for malodor and tar.
[0009]
For these reasons, there is a need for a technique for decomposing halogenated organic compounds, which can make the halogenated organic compounds harmless and cheaper and safer.
[0010]
The present invention has been made in view of the above-described conventional circumstances, and it is possible to safely and inexpensively decompose a halogenated organic compound in a material to be treated, which is a solid substance contaminated with a halogenated organic compound such as dioxins. It is an object of the present invention to provide a decomposing method for detoxification and a decomposing agent therefor.
[0011]
[Means for Solving the Problems]
The method for decomposing a halogenated organic compound according to the present invention (Claim 1) is a treatment target comprising fly ash containing calcium chloride discharged from an incineration facility in which hydrogen chloride in exhaust gas is treated with a calcium-based hydrogen chloride remover. In the method for decomposing a halogenated organic compound in a substance, a chemical containing formic acid and / or formate is added to the substance to be treated and heated.
[0012]
Further, the halogenated organic compound decomposing agent of the present invention contains a fly ash containing calcium chloride discharged from an incineration facility in which hydrogen chloride in exhaust gas is treated with a calcium-based hydrogen chloride removing agent. A decomposition agent for decomposing a halogenated organic compound, comprising formic acid and / or formate .
[0013]
With formic acid and / or formate , the halogenated organic compound in the material to be treated can be safely treated at a relatively low temperature of about 100 to 450 ° C. without generating malodor or tar-like substances like conventional amine compounds. In addition, it can be decomposed and made harmless at low cost.
[0014]
Formic acid and / or formate are also effective for incineration fly ash to which calcium-based alkaline agents were added, which were not sufficiently decomposed by conventional amine compounds unless the temperature was raised to 350 ° C or higher. The halogenated organic compound can be efficiently decomposed by heating at a low temperature.
[0015]
That is, in general, the exhaust gas discharged from the waste incinerator is passed through a boiler, a gas cooling tower, and then sprayed with a calcium-based hydrogen chloride removing agent such as slaked lime or quicklime, and then removed with a dust collector such as a bag filter. Released from the chimney to the atmosphere. In this way, in fly ash discharged from incineration facilities that treat hydrogen chloride in exhaust gas with calcium-based hydrogen chloride removers such as slaked lime and quicklime, calcium-based alkaline agents such as slaked lime and hydrogen chloride Calcium chloride which is a reaction product of is contained. However, calcium chloride in fly ash has a property of strongly adsorbing amine compounds having amine groups as functional groups and polyhydric alcohols having hydroxyl groups. Therefore, when an amine compound or a polyhydric alcohol is added to fly ash containing a calcium-based alkaline agent for the purpose of decomposing dioxins, it is adsorbed by calcium chloride. As a result, diffusion to dioxins present in the fly ash is impeded, so even if amine compounds and polyhydric alcohols are added to the fly ash containing calcium chloride and heated, sufficient dioxin decomposition effects Cannot be obtained. However, with fly ash collected from exhaust gas sprayed as a sodium or potassium alkaline agent as an acid gas adsorbent, amine compounds and polyhydric alcohols are adsorbed to the product sodium chloride and potassium chloride. Since there is no action, these act effectively as dioxins decomposition agents.
[0016]
On the other hand, it has been discovered that formic acid and / or formate acts effectively on fly ash containing calcium chloride. In particular , sodium formate is optimally used as a dioxin decomposing agent for fly ash containing calcium chloride because it is substantially not affected by calcium chloride.
[0017]
When the behavior of the halogenated organic compound in the treated material treated with the decomposition agent according to the present invention is traced, for example, in the case of dioxins, at the beginning of the reaction, first, OCDD (8 chlorinated dibenzo Paradioxin) or OCDF (8 chlorinated dibenzofuran) decreases, and low-chlorine substitutes show an increasing tendency. Furthermore, if the reaction is continued, the reduction of low chlorinated dioxins will proceed. From this, it is presumed that the decomposition reaction of the halogenated organic compound according to the present invention is a sequential dehalogenation reaction .
[0018]
A reactor can be used for heating the substance to be treated. In this case, a powdery or granular decomposition agent is treated in the previous step of supplying the substance to be treated to the reactor or in the reactor. It can be added to and mixed with the substance. As the reactor, it is preferable to use an indirect heating type continuous or batch reactor that does not require a function of actively supplying an inert gas.
[0019]
The addition rate of the decomposition agent of the present invention is preferably 0.1 to 20% by weight as the amount of active ingredient with respect to the substance to be treated, and the heating temperature is preferably 100 to 450 ° C.
[0020]
When the substance to be treated contains heavy metals, it is preferable to further add a heavy metal elution inhibitor to prevent the elution, and in this case, an antielution agent for heavy metals mainly composed of a phosphate compound is used. It is preferable to add and heat to the material to be treated at the same time as the decomposition agent of the present invention or in advance with the decomposition agent of the present invention.
[0021]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the method for decomposing a halogenated organic compound and the decomposing agent of the present invention will be described in detail.
[0022]
First, the halogenated organic compound decomposing agent of the present invention will be described.
[0023]
The halogenated organic compound decomposing agent of the present invention contains formic acid and / or formate . The halogenated organic compound decomposing agent of the present invention is not limited to one containing only formic acid and / or formate, and may contain high molecular aliphatic hydrocarbons, sugars and formic acid and / or formate. It may contain saccharides and formic acid and / or formate . Further, it may contain a polymeric aliphatic hydrocarbon and formic acid and / or formate .
[0024]
In the present invention, examples of the polymer aliphatic hydrocarbon include polyethylene, polypropylene, polystyrene and the like. Among these, polyethylene and / or polypropylene is preferably used because no malodor is generated during the heating reaction. .
[0025]
Examples of the saccharide include monosaccharides such as glucose, fructose and galactose, disaccharides such as sucrose, maltose, lactose and cellobiose, and polysaccharides such as starch and cellulose. In addition, glycosides such as saponin and polymer electrolytes such as lignin are also effective .
[0026]
The halogenated organic compound decomposing agent of the present invention may contain other halogenated organic compound decomposing agents in addition to formic acid and / or formate . Moreover, the below-mentioned heavy metal elution inhibitor may be included.
[0027]
The halogenated organic compound decomposing agent of the present invention is added to a material to be treated consisting of a solid material contaminated with a halogenated organic compound in accordance with the method of the present invention described later. It can also be used effectively to prevent the generation of dioxins.
[0028]
In other words, incineration fly ash in a garbage incinerator is known as a synthesis catalyst for dioxins, but it enters into the texture of the fly ash accumulated in the exhaust gas piping and the dust collector and the filter cloth of the filter dust collector. The fly ash that remains without being dropped will stay for a long time in a temperature environment where dioxins are easy to synthesize, and not only will the dioxins content increase, but also dioxins that have increased in the exhaust gas due to staying in the dust collector May desorb and volatilize again, increasing the concentration of dioxins in the chimney.
[0029]
Accordingly, the halogenated organic compound decomposing agent of the present invention is added to the exhaust gas, mixed in the exhaust gas stream, and deposited on the fly ash by being deposited on the fly ash or mixed with the fly ash. The effect of decomposing the synthesized dioxins and the effect of suppressing the synthesis of dioxins on the fly ash can be obtained.
[0030]
In particular, during start-up and shut-down of the incinerator, a large amount of dioxins and their precursors are generated due to incomplete combustion. For this reason, fly ash with a large amount of dioxins attached is also generated. It is particularly effective to add the decomposition agent of the present invention during the stop operation.
[0031]
The method for decomposing a halogenated organic compound of the present invention uses such a decomposing agent of the present invention to decompose a halogenated organic compound in a material to be treated consisting of a solid substance contaminated with a halogenated organic compound, It is a detoxifying method.
[0032]
In the present invention, by heating was added and mixed formic acid and / or formic acid salt relative to the substance to be treated to decompose the halogenated organic compounds in the treated material, sugars and with formic acid and / or formic acid salt / Or a polymer aliphatic hydrocarbon may be used in combination.
[0033]
The amount of these decomposing agents added to the substance to be treated is appropriately determined according to the type of chemical used and the content of the halogenated organic compound in the substance to be treated, but is usually effective for the substance to be treated. The component amount is preferably 0.1 to 20% by weight, more preferably 0.5 to 15% by weight, and particularly preferably 1 to 10% by weight.
[0034]
In order to heat the substance to be treated together with the decomposer of the halogenated organic compound, a heated reactor may be used, and the substance to be treated and the decomposer may be charged into the reactor. In this case, the decomposition agent can be added to the material to be treated in the form of a powder or granular solid, and may be added and mixed in the previous step before the material to be treated is added to the reactor. You may add and mix with a to-be-processed substance.
[0035]
The heating atmosphere may be an air atmosphere and does not necessarily need to be replaced with an inert gas. Therefore, the function of actively supplying the inert gas to the reactor is not necessary. The heating method is not particularly limited, but it is preferable to use an indirectly heated reactor so that it does not oxidize and burn in the reactor before the decomposition agent acts. Moreover, although it is not an essential requirement, it is preferable that the inhalation of air into the reactor is suppressed.
[0036]
The reactor used may be a continuous type or a batch type. However, in order to achieve uniform contact between the decomposition agent and the substance to be treated, it is desirable to use a reactor having a stirring function. For example, in a continuous type, an indirect heating type rotary kiln, a reactor similar to a paddle dryer having a plurality of stirring paddles, or the like can be used. As a batch reactor, an autoclave having a stirring function or the like However, the present invention is not limited to these.
[0037]
The heating temperature is preferably 100 to 450 ° C, more preferably 100 to 400 ° C, and particularly preferably 150 to 400 ° C. If the heating temperature is less than 100 ° C., a sufficient decomposition effect cannot be obtained, and high-temperature heating exceeding 450 ° C. is disadvantageous in terms of cost and equipment. The heating time varies depending on the heating temperature and the processing amount, but it may be 3 minutes or more, and is usually about 5 to 60 minutes.
[0038]
If the material to be treated contains heavy metals such as fly ash from municipal waste incinerators, the heavy metal leaching prevention treatment is also used in combination with the heavy metal leaching prevention agent to render it harmless. It is preferable to do.
[0039]
There are various organic and inorganic anti-elution agents, such as chelate compounds, but organic anti-elution agents such as chelate compounds are decomposed and lost during heat treatment. After the thermal decomposition treatment of the compound, it is necessary to add and knead it separately from the decomposition agent for the halogenated organic compound. In contrast, an inorganic heavy metal elution preventive agent has no risk of being decomposed by heating, and is added to the substance to be treated together with the halogenated organic compound decomposer during the heat decomposition treatment of the halogenated organic compound. In this case, it can be mixed with a decomposition agent of the halogenated organic compound at a predetermined ratio and added to the material to be treated, which is advantageous in terms of treatment efficiency.
[0040]
Examples of the inorganic heavy metal dissolution inhibitor include the following, among which the phosphate compound is particularly preferable because it can stably fix heavy metals over a long period of time.
[0041]
Orthophosphoric acid (orthophosphoric acid), polyphosphoric acid, metaphosphoric acid, hypophosphoric acid, phosphorous acid, hypophosphorous acid, pyrophosphoric acid, superphosphoric acid, primary phosphate soda, secondary phosphate soda, tertiary phosphate Soda, primary potassium phosphate, secondary potassium phosphate, tertiary potassium phosphate, primary calcium phosphate, secondary calcium phosphate, primary magnesium phosphate, secondary magnesium phosphate, primary ammonium phosphate, secondary phosphate Ammonium, lime superphosphate, sodium tripolyphosphate, potassium tripolyphosphate, sodium hexametaphosphate, potassium hexametaphosphate, sodium pyrophosphate, potassium pyrophosphate, sodium phosphite, potassium phosphite, sodium hypophosphite, hypophosphorous acid Phosphoric acid compounds such as potassium.
[0042]
Cements such as calcined gypsum, Portland cement, early-strength cement, jet cement, blast furnace cement, and alumina cement.
[0043]
Inorganic adsorbents such as various activated clays, synthetic silicic acid and natural silicic acid processed products.
[0044]
Water glass of water-soluble silicates such as general-purpose sodium silicate and potassium silicate.
[0045]
The amount of these heavy metal dissolution inhibitors varies depending on the type of chemicals used and the nature of the material to be treated. In normal cases, the amount of the active ingredient is 0 as an active ingredient content for heavy metal containing materials to be treated such as fly ash in municipal waste incinerators 0.1 to 50% by weight, particularly 1 to 20% by weight is preferable.
[0046]
In addition, when a to-be-processed substance contains a large amount of alkali components, the addition amount of these heavy metal elution inhibitors can also be suppressed low by adding a general-purpose acid beforehand and neutralizing.
[0047]
【Example】
Hereinafter, the present invention will be described more specifically with reference to Examples and Reference Examples.
[0048]
Reference Examples 1-4
As the material to be treated, sodium-based and potassium-based alkaline agents are not added, calcium-based alkaline agents are not included, and fly ash from a waste incinerator containing 729 ng / g of dioxins is used. The treatment was carried out using an indirect heating batch reactor in which the attached three-necked flask was heated with a mantle heater.
[0049]
5% by weight of the decomposition agent shown in Table 1 (both powders) was added to the material to be treated and mixed uniformly, and then charged into the reactor and heat-treated at 300 ° C. for 10 minutes in an air atmosphere. Thereafter, the treated product was allowed to cool naturally, and then the dioxin content of the treated product was measured. The results are shown in Table 1. Further, the decomposition rate of dioxins was calculated from the measurement results, and the results are shown in Table 1.
[0050]
Reference Example 5
The treatment was performed in the same manner as in Reference Example 1 except that no decomposing agent was added, and the results are shown in Table 1.
[0051]
[Table 1]

[0052]
As is clear from Table 1, when heated to 300 ° C. without adding anything (Reference Example 5), dioxins are catalyzed by fly ash from the dioxin precursor contained in the fly ash of the refuse incinerator. On the contrary, the dioxin content of the treated product increased. On the other hand, when various organic acids were added and heated (Reference Examples 1 to 4), dioxins could be decomposed with high efficiency even at a low temperature of 300 ° C.
[0053]
Example 1
A simulated sample is prepared by adding 20% by weight of calcium chloride powder to the incinerator fly ash treated in Reference Example 1, and 5% by weight of sodium formate is added thereto. The decomposition rate of dioxins was examined.
[0054]
When the results were compared with Reference Example 4 in which calcium chloride was not added, the dioxin decomposition rates shown in Table 2 were obtained.
[0055]
[Table 2]

[0056]
【The invention's effect】
As described above in detail, according to the method for decomposing a halogenated organic compound and the decomposing agent of the present invention, the halogenated organic compound in the material to be treated consisting of a solid material contaminated with a halogenated organic compound such as dioxins, It can be safely and inexpensively decomposed and rendered harmless.

Claims (8)

In a method for decomposing a halogenated organic compound in a material to be treated consisting of fly ash containing calcium chloride discharged from an incineration facility treating hydrogen chloride in exhaust gas with a calcium-based hydrogen chloride remover,
A method for detoxifying a halogenated organic compound, comprising adding a chemical containing formic acid and / or formate to the substance to be treated and heating. Oite to claim 1, a method of decomposing the halogenated organic compound by heating by supplying該被treatment substance to the reactor, before supplying該被treatment substance to the reactor, or reaction A method for decomposing a halogenated organic compound, which comprises adding and mixing the powdery or granular drug to the substance to be treated in a container. 3. The method for decomposing a halogenated organic compound according to claim 1, wherein the addition rate of the chemical agent is 0.1 to 20% by weight as an active ingredient with respect to the substance to be treated. The method for decomposing a halogenated organic compound according to any one of claims 1 to 3 , wherein heating is performed using an indirect heating type continuous or batch reactor. The method for decomposing a halogenated organic compound according to any one of claims 1 to 4 , wherein the heating temperature is 100 to 450 ° C. 6. The method for decomposing a halogenated organic compound according to any one of claims 1 to 5 , wherein a heavy metal elution inhibitor is further added to the substance to be treated. 7. The halogen according to claim 6 , wherein a heavy metal elution inhibitor mainly composed of a phosphate compound is added to the substance to be treated and mixed with the chemical at the same time or in advance with the chemical. Of decomposing organic compounds. A decomposition agent for decomposing a halogenated organic compound in a material to be treated consisting of fly ash containing calcium chloride discharged from an incineration facility treating hydrogen chloride in exhaust gas with a calcium-based hydrogen chloride remover. And a halogenated organic compound decomposing agent comprising formic acid and / or formate .