JP3450323B1 - Thermal decomposition treatment method for halogen-containing organic compounds - Google Patents

Abstract

An object of the present invention is to provide a method capable of thermally decomposing a halogen atom-containing organic compound so that a halogen component (particularly, chlorine) and benzene are not discharged to the outside as much as possible. SOLUTION: A halogen atom-containing organic compound is mixed with soil in the presence of metal oxide particles and moisture for 300 to 60 hours.
By heating to a temperature of 0 ° C., a halogen component is eliminated from the halogen-containing organic compound, the halogen component is trapped in a mixture of soil and metal oxide particles, and then the mixture is melted. Fix the halogen component inside,
A method for thermally decomposing an organic compound containing a halogen atom, wherein the organic compound from which a halogen component has been eliminated is reduced and thermally decomposed.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a method for thermally decomposing a halogen atom-containing organic compound.

[0002]

2. Description of the Related Art Organic compounds containing halogen atoms have been widely used as pesticides (insecticides), insulating materials, cleaning agents, and fire extinguishing agents, but their use has been rejected due to environmental problems in recent years. At present, most halogen-containing organic compounds have been discontinued from production and use. However, the halogen atom-containing organic compound is generally a chemically and thermally stable substance, and in the soil polluted by the halogen atom-containing organic compound which has been conventionally used,
It is an environmental problem that halogen-containing organic compounds tend to remain in soil for a long period of time. Therefore, it is desired to decompose the halogen atom-containing organic compound in the contaminated soil as soon as possible to render it harmless. In addition, soils contaminated with dioxins that are unintentionally generated due to the incineration of garbage or solid matters such as incineration ash and fly ash are also problems around the municipal waste incinerator. For this reason, many studies have been conducted aiming at detoxification of soils polluted by organic compounds.

In Patent Document 1, as a method for detoxifying deposits and soil contaminated with organic pollutants and inorganic substances, the deposits and soil are mixed with a calcium oxide source, alumina, iron oxide, and a flux. There is disclosed a method of heating these to melt them and then cooling them to obtain an amorphous substance (glass vitrified body).

In Patent Document 2, as a method of detoxifying incinerated ash or molten ash contaminated with harmful organic compounds such as dioxins, the incinerated ash or molten ash is mixed with SiO ₂ or Al ₂ O ₃ and heated. A method of doing so is disclosed.

[0005]

[Patent Document 1] Japanese Patent Publication No. 2001-506964

[Patent Document 2] Japanese Patent Laid-Open No. 2000-51818

[0006]

If the soil or solid matter contaminated with the halogen atom-containing organic compound is heated to thermally decompose the halogen atom-containing organic compound, the soil or solid matter is rendered harmless. Similarly, a halogen atom-containing organic compound such as an agricultural chemical or a liquid, powder or lump containing the same can be heated and pyrolyzed. However, even if a halogen atom-containing organic compound is heated and once pyrolyzed, dioxins may be produced if a halogen component (especially chlorine) or an organic compound (especially benzene) is present in the decomposition product gas. is there.

Therefore, an object of the present invention is to eliminate halogen atom-containing organic compounds in soil contaminated by halogen atom-containing organic compounds from halogen component gas (especially chlorine gas) and organic compounds (especially benzene) as much as possible. It is an object of the present invention to provide a method that can be pyrolyzed without being discharged. The object of the present invention is also to provide a method capable of thermally decomposing a halogen atom-containing organic compound in a solid material contaminated by a halogen atom-containing organic compound without discharging the halogen component gas or the organic compound as much as possible to the outside. To provide. A further object of the present invention is to thermally decompose a halogen atom-containing organic compound or a liquid, powder or lump containing the halogen atom-containing organic compound without discharging the halogen component gas or the organic compound as much as possible to the outside. It is to provide a method that can.

[0008]

Means for Solving the Problems The present inventor has found that an organic compound containing a halogen atom is used together with soil in activated alumina or surface.
3 in the presence of metal oxide particles having pores and water
The halogen component (especially chlorine) is desorbed from the halogen atom-containing organic compound by heating to a temperature of 00 to 600 ° C., and the halogen component is deposited on the soil and the activated alumina or the surface.
Trapped in a mixture with metal oxide particles having pores ,
Then, by melting the mixture and fixing the halogen component in the melt, the amount of halogen component in the decomposition product gas can be reduced, and the organic compound (especially benzene) from which the halogen component has been desorbed is present in the presence of water. The organic compounds are efficiently decomposed by reductive thermal decomposition under
The present invention has been achieved by finding that the amount of organic compounds in the decomposition product gas can be reduced.

In the present invention, the soil polluted by a halogen atom-containing organic compound is treated with activated alumina or a surface with pores.
300-6 in the presence of metal oxide particles having
Heating to a temperature of 00 ° C. to desorb the halogen component from the halogen atom-containing organic compound and trap the halogen component in a mixture of soil and activated alumina or metal oxide particles having pores on the surface , Then, the mixture is melted to fix a halogen component in the melt, and the organic compound from which the halogen component is desorbed is subjected to reductive thermal decomposition, which is a thermal decomposition treatment method for a halogen atom-containing organic compound.

The present invention also includes activated alumina or surface fine particles.
300-in the presence of metal oxide particles having pores and water
Heating to a temperature of 600 ° C. to desorb the halogen component from the halogen atom-containing organic compound, and capture the halogen component in a mixture of soil and activated alumina or metal oxide particles having pores on the surface , Next, there is also a method for thermally decomposing a halogen atom-containing organic compound, characterized in that the mixture is melted to fix a halogen component in the melt, and the organic compound from which the halogen component has been eliminated is subjected to reductive thermal decomposition. . Here, the soil used for heating together with the contaminated solid matter means an inorganic matter produced by decomposition of rocks or the like on the surface of the crust, and may or may not have an organic matter such as a corrosive matter.

The present invention further comprises a halogen atom-containing organic compound or a liquid, powder or lump containing the halogen atom-containing organic compound together with soil, activated alumina or
Is heated to a temperature of 300 to 600 ° C. in the presence of metal oxide particles having pores on the surface and water to separate the halogen component from the halogen atom-containing organic compound, and the halogen component is removed from the soil and the activated alumina. Alternatively , it is trapped in a mixture with metal oxide particles having pores on the surface , then the mixture is melted to fix the halogen component in the melt, and the organic compound from which the halogen component is desorbed There is also a method for thermally decomposing a halogen atom-containing organic compound, which comprises reductively decomposing the compound. Here, the soil used when heating together with a halogen atom-containing organic compound and the like means an inorganic substance generated by decomposition of rocks or the like on the surface of the crust, and may or may not have an organic substance such as a corrosive substance.

A preferred embodiment of the method for thermally decomposing a halogen atom-containing organic compound of the present invention is as follows. (1) Activated alumina has pores on the surface. (2) The metal oxide particles are activated alumina. (3) The mixture is melted by using Joule heat generated by passing an electric current between two or more electrodes embedded in the mixture. (4) The mixture is melted inside the hole formed in the ground. (5) The melting of the mixture is performed inside a container that is movably installed on the ground. (6) The halogen atom-containing organic compound is a chlorine atom-containing organic compound.

[0013]

BEST MODE FOR CARRYING OUT THE INVENTION In the method of the present invention, the halogen atom-containing organic compound to be decomposed is not particularly limited. The method of the present invention has a volatilization temperature (boiling point) of 1
It is particularly useful for decomposition treatment of halogen atom-containing organic compounds at a temperature of 00 ° C or higher (particularly 100 to 300 ° C). Typical examples thereof are hexachlorobenzene (HCB), hexachlorocyclohexane (BHC), p, p'-dichlorodiphenyltrichloroethane (DDT), chlordane, organochlorine pesticides such as endrin, and polychlorinated biphenyls (PCB). , And dioxins and other hardly decomposable chlorine atom-containing organic compounds.

In the present invention, the halogen atom-containing organic compound is heated with soil in the presence of activated alumina or metal oxide particles having pores on the surface thereof and water.

The activated alumina preferably has pores on the surface so that the halogen component desorbed from the halogen atom-containing organic compound can be efficiently captured. Pores on the surface
As a specific example of the metal oxide particles having , activated alumina (alumina containing γ-alumina as a main component) can be mentioned. The activated alumina also acts as a decomposition accelerator for the halogen atom-containing organic compound. The activated alumina used in the method of the present invention has a specific surface area of 50 to 50.
Range of 0 m ² / g, it is preferable that in particular in the range of 50 to 300 m ² / g.

As a method of allowing water to exist when the halogen atom-containing organic compound is heated together with the soil, for example, a method of previously adding water or a compound which generates steam by heating to the soil can be mentioned. Examples of compounds that generate water vapor when heated include water-retaining substances such as bentonite and metal hydroxides. Examples of metal hydroxides include sodium hydroxide, magnesium hydroxide, calcium hydroxide,
And aluminum hydroxide. Also,
As another method of allowing water to exist in the soil when heating,
A method may also be used in which an inlet for supplying steam or water is provided in a melting furnace for heating and melting the soil, and steam or water is supplied while heating and melting the soil.

Further, an alkali metal compound or an alkaline earth metal compound which acts as a depressant for the melting point (vitrification temperature) of the soil may be added to the soil. Examples of alkali metal compounds or alkaline earth metal compounds include sodium carbonate, magnesium carbonate, and calcium carbonate, sodium hydroxide, magnesium hydroxide, and calcium hydroxide.

A method of thermally decomposing a halogen atom-containing organic compound in a contaminated soil will be described below by taking a contaminated soil as an example of a treatment object. Examples of the contaminated soil to be treated in the method of the invention include HCB and BH.
Agricultural land soil sprayed with organochlorine pesticides such as C, DDT, chlordane, and endrin, soil around factories that manufacture or use organic compounds containing halogen atoms, and dioxin-contaminated soil around municipal waste incinerators Can be mentioned. The amount of the halogen atom-containing organic compound in the contaminated soil is generally in the range of 0.01 to 50% by mass, particularly 1 to 50% by mass, and further 2 to 40% by mass.

First of all, activated alumina or
Metal oxide particles having pores on the surface, and if necessary, water or a compound that generates water vapor by heating, and an alkali metal compound or an alkaline earth metal compound as a melting point depressant are added and mixed to obtain a contaminated soil mixture. To get Instead of activated alumina or metal oxide particles having pores on the surface, activated alumina or
A compound that produces metal oxide particles having pores on the surface may be added to the contaminated soil. A specific example of this compound is aluminum hydroxide which forms activated alumina at a temperature of 600 ° C. or lower.

Pores on the contaminated soil and activated alumina or surface
A known mixer such as a drum mixer or a paddle mixer can be used for mixing with the metal oxide particles. The addition amount of activated alumina or metal oxide particles having pores on the surface varies depending on the content of the halogen atom-containing organic compound in the contaminated soil, but is generally 0.1 to 100 parts by mass with respect to 100 parts by mass of the contaminated soil. Parts by weight, preferably 1 to 50 parts by weight. Further, based on the amount of halogen atom-containing organic compound in the contaminated soil, the addition amount of activated alumina or metal oxide particles having pores on the surface is 0 with respect to 100 parts by weight of the halogen atom-containing organic compound. 1 to 1000 parts by mass,
It is preferably in the range of 1 to 500 parts by mass.

Next, the contaminated soil mixture is heated to desorb the halogen component from the halogen atom-containing organic compound, and the halogen component has pores in the soil and the activated alumina or on the surface.
Entrapped in a mixture with metal oxide particles, which is then melted to immobilize the halogen component in the melt,
Then, the organic compound from which the halogen component is desorbed is thermally decomposed by reduction. It is preferable to carry out the series of heating operations using one melting furnace.

The contaminated soil mixture is heated by filling the contaminated soil mixture in a hole formed in the ground or in a heat-resistant container movably installed on the ground, and filling the contaminated soil mixture from top to bottom. It is preferable to use a method of heating and melting. As a method of heating and melting the contaminated soil mixture, it is preferable to use a method of utilizing Joule heat generated by passing an electric current between two or more electrodes embedded in the mixture. Even when the above-mentioned contaminated soil mixture is heated inside the hole formed in the ground, in consideration of contamination of the surrounding soil, a container is installed in the ground in advance, and inside the container, It is preferably carried out.

A method of heating a contaminated soil mixture using Joule heat will be described below with reference to the accompanying drawings.

First, as shown in FIG. 1, a heat-resistant container is filled with a contaminated soil mixture. The packing density of the contaminated soil mixture 1 in the container 2 is generally in the range of 1 to 2 ton / m ³ . The filling volume of the contaminated soil mixture 1 in the container 2 is generally preferably 1 m ³ or more (particularly 5 to 10 m ³ ). The shape of the opening of the heat-resistant container 2 can be various shapes such as a rectangular shape, a shape in which four corners of a rectangle are cut (octagonal shape), and a circular shape, but the shape in which the four corners of a rectangle are cut off. Is preferred.

In FIG. 1, the heat-resistant container 2 has a double structure of an inner container 3 and an outer container 4. The inner container 3 is preferably formed of ceramic powder such as silica sand (silicon dioxide powder). The inner container 3 has a thickness that increases in order to increase heat resistance as it goes downward. This is because the heat of the molten soil tends to spread laterally as the melting progresses downward. The thickness of the inner container 3 is generally in the range of 10 to 20 cm above (thin portion of thickness) and below (thick portion of).
The thickness is preferably 1.1 to 2 times the thickness of the upper part.

The outer container 4 is preferably made of a material having low gas permeability so that the decomposition products of the halogen atom-containing organic compound do not scatter to the outside. Examples of the material include refractory bricks, refractory castables, and various heat insulating materials (eg, ceramic fiber, calcium silicate,
Perlite, rock wool, asbestos, diatomaceous earth, glass wool, magnesium carbonate) and the like.

Next, as shown in FIG. 2 and FIG. 3, a soil not containing a halogen atom-containing organic compound is practically covered on the contaminated soil mixture 1 to form a coated soil layer 5. Then, on the coated soil layer 5, an initial conductive resistance path 6 for converting electric energy into thermal energy (Joule heat),
An electrode 7 for supplying electric energy to the initial conductive resistance path 6 is arranged in this order. FIG. 2 is a cross-sectional view of an example of a container in which a coated soil layer, an initial conductive resistance path, and electrodes are arranged on a contaminated soil mixture, and FIG. 3 is a top view of the heat-resistant container of FIG. It is a top view.

The coated soil layer 5 has a function of melting before the contaminated soil mixture 1 and uniformly heating the entire surface of the contaminated soil mixture 1. By providing the coated soil layer 5,
The contaminated soil mixture 1 can be uniformly heated and melted. The thickness of the coated soil layer 5 is generally 1 to 100 c
It is in the range of m, and preferably in the range of 10 to 60 cm. The composition of the soil used for the coated soil layer 5 is not particularly limited as long as it is a soil substantially free of a halogen atom-containing organic compound. Here, "substantially free of a halogen atom-containing organic compound" means that the content of the halogen atom-containing organic compound is less than 0.01% by mass. An aluminum compound which produces aluminum oxide by heating, a silicon compound which produces silicon oxide by heating, or metallic aluminum may be added to the soil used for the coated soil layer 5.

As shown in FIG. 3, the initial conductive resistance band 6 is a rectangular plate-like body and has four electrodes 7a, 7b, 7
It is arranged so as to be connected to each of c and 7d.
The initial conductive resistance band 6 does not necessarily have to be a plate-shaped body and may be, for example, a rod-shaped body. When the rod-shaped initial conductive resistance band is used, the initial conductive resistance band is arranged so that the electrodes 7a, 7b, 7c, and 7d are electrically connected.

The material of the initial conductive resistance band 6 is not particularly limited as long as it has a function of converting electric energy into heat energy (Joule heat). Examples of the material of the initial conductive resistance zone 6 include graphite, and a mixture of graphite and a melting temperature lowering agent for soil. Examples of the melting temperature lowering agent for soil include alkali salts such as sodium hydroxide and sodium carbonate, and glass frit.

The electrodes 7a, 7b, 7c, 7d are fixed to an electrode feed device (not shown) whose tip is movable in the vertical direction. Examples of the material of the electrode 7 include metals such as graphite and molybdenum. An electrode 7a and an electrode 7b, and an electrode 7b and an electrode 7c, which are arranged on a diagonal line, are set as one set, and an alternating current pressure with a phase difference of 90 degrees is supplied to each set,
Uniform electrical energy can be supplied to the initial conductive resistance path.

Next, as shown in FIG. 4, the opening of the container 2 is covered with a hood. FIG. 4 is a cross-sectional view of an example of a container covered with a hood. In FIG. 4, the hood 8 is provided with a gas introduction port 9 on a side portion and an exhaust port 10 on an upper portion. In order to prevent dioxins from being generated from the decomposition product gas of the halogen atom-containing organic compound in the hood 8, the gas introduction port 9 has a temperature of 300 ° C. or higher (usually 30 ° C.).
Hot air of 0 to 800 ° C.) is supplied. Exhaust port 10
Is an exhaust port of a decomposition product gas of a halogen atom-containing organic compound. The hood 8 is preferably formed of a material having low gas permeability so that decomposition products of the halogen atom-containing organic compound do not scatter to the outside. Examples of the material include metals such as iron and stainless steel.

Next, as shown in FIG. 5, an electric energy supply device is connected to the electrode 7, an air heating device is connected to the gas introduction port 9 of the hood, and a gas treatment device is connected to the exhaust port 10.

FIG. 5 is a schematic view showing an example of the constitution of a treatment system for a contaminated soil mixture using a melting furnace (electric resistance type melting furnace) manufactured by the steps shown in FIGS. In FIG. 5, the treatment system for contaminated soil mixture is
The melting furnace 11, the electric energy supply device 12 for supplying electric energy to the melting furnace 11, the gas processing device 13 for processing the gas discharged from the melting furnace 11, and the high-temperature air sent to the melting furnace 11 are adjusted. Air heating device 14
Consists of. The electric energy supply device 12 is a self-power generation type device, and includes a generator 15 and a transformer 16. The gas treatment device 13 includes a secondary heating facility 17, a cooling dust remover (venturi scrubber) 18, a HEPA filter 19, and an activated carbon filter 20.

The electric energy supply device 12 is a generator 1.
The electric energy generated in 5 is adjusted to a predetermined electric power by the transformer 16 and supplied to the melting furnace 11. Melting furnace 11
The electrical energy supplied to the electrode is sent to the initial conductive resistance path 5 through the electrode 7. The initial conductive resistance path 6 converts electric energy into heat energy (Joule heat). The heat causes the soil in the coated soil layer 5 to be heated and melted.

The heat distribution of the soil mixture when the coated soil layer is melted is shown schematically in FIG. In FIG. 6, the contaminated soil mixture 1 is heated by the melt 5a of the coated soil layer and heated to 300 ° C. or higher in the region 1a, 100 ° C. to 3 ° C.
It is divided into a region 1b heated to 00 ° C. and a region 1c below 100 ° C. The temperature of the melt 5a in the coated soil layer is 1300 ° C or higher (usually 1300 to 1600).
℃). In the region 1b, the halogen atom-containing organic compound and water in the contaminated soil mixture are volatilized, and the contaminated soil is rendered harmless. The volatile halogen atom-containing organic compound is
In the region 1a, 300 ° C or higher (usually 300 to 600
When heated to a temperature of (.degree. C.), the halogen component of the halogen atom-containing organic compound is eliminated. The halogen component desorbed from the halogen-containing organic compound is the soil and activated alumina or
Mixture with metal oxide particles having pores on the surface (mainly,
Activated alumina or metal oxide particles having pores on the surface )
Caught inside. Then, the mixture in which the halogen component is captured is further heated to 1300 ° C. or more to be melted to be a melt, but all or most of the halogen component captured in the mixture is fixed in the melt. On the other hand, the organic compound from which the halogen component is desorbed undergoes reductive thermal decomposition in the presence of water to generate carbon monoxide and hydrogen. The carbon monoxide gas and the hydrogen gas are oxidized by oxygen in the high temperature air introduced from the gas inlet 9 to become carbon dioxide gas and water (steam), respectively.

After the entire amount of the contaminated soil mixture is melted, the supply of electric energy to the melting furnace 11 is stopped, and the melted soil is cooled and solidified into glass. In the obtained vitrified body, the halogen component fixed in the melt is confined as it is. However, since the vitrified body does not substantially contain a halogen atom-containing organic compound and is physically and chemically stable, it can be crushed and used as a recycled crushed stone or the like.

The treatment of the decomposition product gas produced by the above heat treatment will be described with reference to FIG. The decomposition product gas of the halogen atom-containing organic compound is sent from the exhaust port 10 of the hood 8 to the gas treatment device 13.

The secondary heating equipment 17 supplies the decomposition product gas to 85
Heat to a temperature of 0 ° C. or higher (usually 900 to 1000 ° C.) for 2 seconds or longer. By this heating, a volatile gas of an organic compound containing a halogen atom and an organic compound (eg, benzene, dioxins) which may be present in the decomposition product gas very slightly are oxidatively pyrolyzed. The cooling dust remover 18 removes the decomposition product gas heated in the secondary heating equipment 17 to 100 ° C.
It is rapidly cooled to the following, and an acidic gas such as a hydrogen halide gas contained therein is neutralized to remove particles. HEP
The A filter 19 and the activated carbon filter 20 further collect the volatile gas and organic compound of the halogen atom-containing organic compound in the decomposition product gas that may be present in a very small amount. The decomposition product gas processed by the gas processing device 13 is released to the outside.

In the above, the method of the present invention has been described with reference to a representative example of a contaminated soil as an object to be treated. A solid matter contaminated with a halogen atom-containing organic compound and a halogen atom-containing organic material Liquids, powders or lumps containing compounds or organic compounds containing halogen atoms can be treated in the same manner.

That is, when the object to be treated is a contaminated solid, it can be treated as follows, for example. First, activated alumina or pores are formed on the surface of soil that does not practically contain a halogen atom-containing organic compound or has a small content of a halogen atom-containing organic compound.
The activated alumina with a metal oxide particles or heating to
Is a substance that produces metal oxide particles having pores on the surface ,
Further, if necessary, water or a compound that generates steam by heating and an alkali metal compound or an alkaline earth metal compound as a melting point depressant are added and mixed to obtain a contaminated solid mixture. Here, "the content of the halogen atom-containing organic compound is small" means that the content of the halogen atom-containing organic compound is in the range of 0.01 to 1% by mass. Then, this contaminated solid is heated in the same manner as the above-mentioned contaminated soil mixture to fix the halogen component of the halogen atom-containing organic compound to the melt of the mixture, and the organic compound component is thermally decomposed by reduction. Halogen atom-containing organic compound 1
The amount of soil used with respect to parts by mass is generally 1 to 1000.
The amount is in the range of 0 parts by weight, preferably in the range of 1 to 100 parts by weight.

In the present invention, examples of contaminated solids to be treated include PCB-containing containers, incinerated ash discharged in a municipal waste incinerator, fly ash, refractory materials (brick) in the municipal waste incinerator, And sludge discharged from a factory that manufactured or used a halogen atom-containing organic compound.

The object to be treated is a halogen atom-containing organic compound or a liquid substance containing a halogen atom-containing organic compound,
The powder or lump can be treated as follows, for example. First, in the soil which does not substantially contain a halogen atom-containing organic compound or has a small content of a halogen atom-containing organic compound, a liquid material containing a halogen atom-containing organic compound or a halogen atom-containing organic compound, a powder or Lumps, activated alumina or
Metal oxide particles with pores on the surface or by heating
Activated alumina or a compound that forms metal oxide particles having pores on the surface, and if necessary, a compound that generates water vapor by heating with water, and an alkali metal compound or an alkaline earth metal compound as a melting point depressant are added. And mixed to obtain a mixture. And this mixture
It heats like the said contaminated soil mixture, the halogen component of a halogen atom containing organic compound is fixed to the melt of a mixture, and an organic compound component is reduced-pyrolysis. The amount of soil used per 1 part by mass of the halogen atom-containing organic compound is generally in the range of 1 to 10000 parts by mass, preferably 1 to 100 parts by mass.

In the method of the present invention, when a halogen atom-containing organic compound or a liquid, powder or lump containing the halogen atom-containing organic compound is contained in a container, the whole container is mixed with the soil for treatment. can do. For example, a transformer or capacitor in which PCB is used can be mixed with soil as it is for processing. Examples of liquids, powders or lumps containing a halogen atom-containing organic compound to be treated in the present invention include pesticides (insecticides), insulating materials and detergents containing a halogen atom-containing organic compound as an active ingredient. , And a digestive agent.

1 to 5, the case where the contaminated soil mixture is heated and melted by using Joule heat has been described, but the contaminated soil mixture filled in the melting furnace is heated in order from the upper side to the lower side. Then, as long as it can be melted, the method for heating and melting the contaminated soil mixture is not particularly limited. For example, plasma may be used to heat and melt the contaminated soil mixture.

[0046]

EXAMPLES The present invention will be described below with reference to examples. The soil components used in this example are as follows.

[0047]

[Table 1] Table 1 ────────────────────────── Al ₂ O ₃ 11.1% by mass CaO 4.2% by mass K ₂ O 2.6 wt% MgO 2.1 wt% MnO 0.04 wt% NaO ₂ 3.7 wt% P ₂ O ₅ 0.04 wt% SiO ₅ 61.4 wt% TiO ₂ 0.7 wt% Fe ₂ O ₃ 4.5% by mass Organic compound containing halogen atom Less than 0.01% by mass ──────────────────────────

Example 1 Soil 385 kg, activated alumina (specific surface area: 50 m ² / g) 107 kg, sodium carbonate 52 kg, calcium carbonate 91 kg, powdery hexachlorobenzene (HCB) 285 kg, and water 55
In this order, kg was charged into a drum (capacity: 2 m ³ ). Next, the lid of the drum can was closed, the drum was attached to the rotary mixer, and the drum was rotated together with it to prepare a mixture.

The total amount of the resulting mixture (975 kg) was
The heat-resistant container 2 shown in FIG. 1 having an open top (opening size: 1.1 m in length × 1.1 m in width × 1.5 m in depth) was filled. Next, as shown in FIG. 2 and FIG. 3, the mixture is covered with soil having the composition shown in Table 1 above to form a coated soil layer 5 having a thickness of 40 cm, and then the coated soil layer 5 is initially filled with the soil. The conductive resistance band 6 (material: a mixture of graphite and glass frit) is filled, and the four electrodes 7 are provided on the initial conductive resistance band 6.
a, 7b, 7a, 7b (diameter: 100 mm) were arranged. Then, as shown in FIG. 4, on the upper portion of the heat resistant container 2,
A hood 8 having a gas inlet 9 and an exhaust port 10 was installed.

High temperature air of 500 ° C. was sent to the gas inlet of the hood 8 to adjust the temperature inside the hood to 500 ° C. Then, between the electrodes 7a and 7d, and between the electrodes 7b and 7c.
An alternating voltage is applied to each of these to supply electric energy to the initial conductive resistance band to heat the coated soil layer to form a melt having a temperature of 1300 ° C or higher, and the mixture is heated to 300 ° C to 6 ° C.
Heated to a temperature of 00 ° C. Further, electric energy was continuously supplied to the melt, and the mixture was heated and melted. After melting the entire amount of the mixture, the supply of electric energy was stopped and the molten mixture was cooled to solidify into a glass.

H in the exhaust gas discharged from the exhaust port of the hood from the start of the supply of electric energy to the initial conductive resistance band until the molten mixture solidifies into a glass.
From the amount of CB (P) and the amount of HCB (A ₁ ) in the vitrified body after the treatment, the HCB decomposition rate (%) was calculated by the following formula, and as a result, it was confirmed to be 99.5% by mass. Moreover, as a result of analyzing the components of the exhaust gas, it was confirmed that most of them were carbon dioxide and water.

[0052]

[Equation 1] HCB decomposition rate (%) = {1- (P + A ₁ ) /
A ₀ } × 100 where P is the amount of HCB in the exhaust gas (kg), A ₁ is the amount of HCB in the vitrified body (kg, but substantially 0),
A ₀ is the amount of HCB (285 kg) in the mixture before treatment.

Example 2 A chlordane emulsion was used as the halogen atom-containing organic compound, and the mixing ratio was set to 540 in soil.
4 kg, activated alumina (specific surface area: 300 m ² / g) 3
A mixture was prepared in the same manner as in Example 1 except that 62 kg, chlordane emulsion 140 kg (chlorine amount about 35 kg), and water 277 kg were used.

Total amount of mixture obtained (6183 kg)
The opening size is 1.7 m in length x 1.7 m in width x depth 1.
The procedure of Example 1 was repeated, except that a 6 m heat-resistant container was used, to heat and melt.

As a result of measuring the decomposition rate of chlordane by the same method as in Example 1, it was confirmed to be 99.9999% by mass or more. It was also confirmed that most of the exhaust gas components were carbon dioxide and water. Furthermore, as a result of measuring the amount of chlorine in the vitrified body by fluorescent X-ray, 25 kg of chlorine was fixed in the vitrified body, and about 71 mass% of chlorine in chlordane was fixed in the vitrified body. Was confirmed.

[0056]

EFFECTS OF THE INVENTION According to the method for decomposing a halogen atom-containing organic compound of the present invention, the halogen component of the halogen atom-containing organic compound is formed into pores in the soil and the activated alumina or the surface.
Since it is fixed to the melt with the metal oxide particles that it has, the amount of halogen components in the decomposition product gas is reduced. In addition, since the organic compound from which the halogen component is desorbed is thermally decomposed by reduction in the presence of water, the organic compound is efficiently decomposed and the amount of the organic compound in the decomposition product gas is reduced. Therefore, dioxins are less likely to be generated in the decomposition product gas.

[Brief description of drawings]

FIG. 1 is a cross-sectional view showing an example of a heat-resistant container filled with contaminated soil.

FIG. 2 is a cross-sectional view of a heat-resistant container in which a coated soil layer, an initial conductive resistance path, and electrodes are arranged.

FIG. 3 is a plan view of the heat resistant container of FIG. 2 seen from above.

FIG. 4 is a cross-sectional view of an example of a heat-resistant container covered with a hood.

FIG. 5 is a schematic diagram showing an example of the configuration of a contaminated soil mixture processing system using a melting furnace that uses Joule heat.

FIG. 6 is a diagram schematically showing a heat distribution of a contaminated soil mixture when the contaminated soil mixture is heated by using a melting furnace using Joule heat.

[Explanation of symbols]

1 Contaminated soil mixture 2 heat-resistant container 3 inner container 4 outer container 5 Covered soil layer 6 Initial conductive resistance path 7, 7a, 7b, 7c, 7d electrodes 8 hood 9 gas inlet 10 exhaust port 11 melting furnace 12 Electric energy supply equipment 13 Gas processing equipment 14 Air heating device 15 generator 16 transformer 17 Secondary heating equipment 18 Cooling Dust Cleaning Machine (Venturi Scrubber) 19 HEPA filter 20 Activated carbon filter

─────────────────────────────────────────────────── ─── Continuation of front page (56) References JP 2001-233621 (JP, A) JP 2002-35736 (JP, A) JP 4-118414 (JP, A) JP-B 2-43847 ( JP, B1) (58) Fields surveyed (Int.Cl. ⁷ , DB name) B09C 1/06 B09B 3/00 E02D 3/11 A62D 3/00

Claims (13)

(57) [Claims] 1. A soil contaminated with a halogen atom-containing organic compound is treated in the presence of activated alumina and water in an amount of 30%.
The halogen component is desorbed from the halogen atom-containing organic compound by heating to a temperature of 0 to 600 ° C., the halogen component is trapped in a mixture of soil and activated alumina, and then the mixture is melted to melt the mixture. A method for thermally decomposing an organic compound containing a halogen atom, which comprises fixing a halogen component to an object and reductively pyrolyzing the organic compound from which the halogen component is desorbed. 2. A solid matter contaminated with a halogen atom-containing organic compound is heated together with soil to a temperature of 300 to 600 ° C. in the presence of activated alumina and water to desorb the halogen component from the halogen atom-containing organic compound. The halogen component is trapped in a mixture of soil and activated alumina , then the mixture is melted to fix the halogen component in the melt, and the organic compound from which the halogen component is desorbed is reduced and thermally decomposed. A method for thermally decomposing a halogen atom-containing organic compound, comprising: 3. A halogen atom-containing organic compound or a liquid, powder or lump containing a halogen atom-containing organic compound is heated together with soil to a temperature of 300 to 600 ° C. in the presence of activated alumina and water, The halogen component is desorbed from the halogen atom-containing organic compound, the halogen component is trapped in a mixture of soil and activated alumina, and then the mixture is melted to fix the halogen component in the melt, and A method for thermally decomposing a halogen atom-containing organic compound, which comprises thermally decomposing an organic compound from which components have been eliminated. 4. The method for thermally decomposing a halogen atom-containing organic compound according to any one of claims 1 to 3, wherein the activated alumina has pores on its surface. 5. The specific surface area of activated alumina is 50 to 50.
The thermal decomposition treatment method for a halogen atom-containing organic compound according to any one of claims 1 to 4, which is in a range of 0 m ² / g . 6. The method according to claim 1, wherein the reduced thermal decomposition product of the organic compound is oxidized and then discharged to the outside.
The method for thermally decomposing a halogen atom-containing organic compound according to any one of 1. 7. The method according to claim 1, wherein the mixture is melted by utilizing Joule heat generated by passing an electric current between two or more electrodes embedded in the mixture. 5. A method for thermally decomposing a halogen atom-containing organic compound according to the above item. 8. The thermal decomposition treatment of a halogen atom-containing organic compound according to claim 1, wherein the melting of the mixture is performed inside a hole formed in the ground. Method. 9. The heat of the halogen atom-containing organic compound according to claim 1, wherein the melting of the mixture is performed inside a container that is movably installed on the ground. Decomposition method. 10. The method for thermally decomposing a halogen atom-containing organic compound according to any one of claims 1 to 9, wherein the halogen atom-containing organic compound is a chlorine atom-containing organic compound. 11. A halogen atom-containing organic compound
Metal oxide particles with pores on the surface of contaminated soil
And heating to a temperature of 300 to 600 ° C. in the presence of water,
Desorption of halogen component from the halogen atom-containing organic compound
And mix the halogen component with soil and metal oxide particles.
Entrapment in a mixture and then melting the mixture to form the melt
The halogen component is fixed inside, and the halogen component is desorbed.
Halo characterized by reductive thermal decomposition of organic compounds
A method for thermally decomposing an organic compound containing a gen atom. 12. A halogen atom-containing organic compound
Contaminated solids along with soil, gold with pores on the surface
A temperature of 300 to 600 ° C in the presence of metal oxide particles and water
The halogen atom-containing organic compound
The halogen component is desorbed and the halogen component is oxidized to soil and metal.
Entrapped in a mixture with particulates and then melted the mixture.
To fix the halogen component in the melt.
The special feature is the reduction and thermal decomposition of organic compounds from which
Method of thermal decomposition of organic compounds containing halogen atoms
Law. 13. A halogen atom-containing organic compound or
Liquids, powders or halogen-containing organic compounds
Has lumps with soil and has pores on the surface Metal oxide
Heat to a temperature of 300-600 ° C in the presence of particles and moisture
The halogen component from the halogen atom-containing organic compound.
It is desorbed and the halogen component is separated from the soil and the metal oxide particles.
Entrapped in a mixture of
Fix the halogen component in the melt, and
Characterized by reductive thermal decomposition of released organic compounds
A method for thermally decomposing an organic compound containing a halogen atom.