JP2001252637A - Method for treating halogenated organic compound- containing contaminated sold - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for treating halogenated organic compound- containing contaminated solid capable of efficiently decomposing a harmful halogenated organic compound such as dioxins and also capable of reclaiming the treated material as it is without needing the post-treatment of the treated material. SOLUTION: In the method for treating the helogenated organic compound- containing contaminated solid, the contaminated solid containing the halogenated organic compound is decomposed by heating and kneading the contaminated solid with asphalt and an alkali metal compound.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a method for treating contaminated solids containing a halogenated organic compound,
For example, a treatment method for detoxifying harmful halogenated organic compounds in contaminated solids such as contaminated soil, municipal incineration ash, fly ash, molten fly ash, and industrial waste containing toxic halogenated organic compounds such as dioxins. .

[0002]

2. Description of the Related Art In recent years, as garbage and waste generated from cities and factories have increased remarkably, incinerated ash, fly ash or molten fly ash discharged by incineration not only contains a large amount of heavy metals but also heavy metals. It contains a large amount of halogenated organic compounds such as dioxins. In addition, soil pollution by dioxins discharged from incinerators and the like has been observed, and safe detoxification of these has been desired in environmental measures.

[0003] Chelate and cement methods are used for sealing heavy metals, but these methods cannot decompose harmful dioxins. On the other hand, as a method for decomposing dioxins, various decomposition methods such as thermal decomposition, chemical decomposition, and microbial decomposition methods have been developed. Speaking of chemical degradation, for example, US Pat.
No. 7 discloses a method using a reaction product of an alkali metal or an alkali metal hydroxide with polyglycol or polyglycol monoalkyl ether. JP-A-8-141107 discloses a method in which a halogenated organic compound is dissolved in a high-boiling hydrocarbon oil and heat-treated together with an alkali metal compound. However, polyglycols and hydrocarbon solvents remain in the processed products treated by these methods, and cannot be buried as they are. Further post-treatments such as oxidative decomposition and extraction of the solvents are required.

[0004]

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems, and it is an object of the present invention to remove harmful halogenated compounds such as dioxins in contaminated solids containing halogenated organic compounds. An object of the present invention is to provide a method for treating a contaminated solid containing a halogenated organic compound, which can efficiently decompose an organic compound and bury the treated product without post-treatment.

[0005]

Means for Solving the Problems As a result of intensive studies, the present inventor has found that a contaminated solid containing a halogenated organic compound is
It has been found that the object of the present invention can be effectively achieved by heating and kneading with asphalt and an alkali metal compound, and the present invention has been completed based on this finding. That is, the gist of the present invention is as follows. 1. A method for treating a halogenated organic compound-containing contaminated solid, comprising decomposing the halogenated organic compound by heating and kneading the contaminated solid containing the halogenated organic compound together with asphalt and an alkali metal compound. 2. The method for treating a contaminated solid containing a halogenated organic compound as described in 1 above, wherein the solid is heated and kneaded at 200 ° C. or higher. 3. 3. The method for treating a contaminated solid containing a halogenated organic compound as described in 1 or 2, wherein the asphalt has a penetration of 100 or less. 4. 4. The method for treating a halogenated organic compound-containing contaminated solid according to any one of the above items 1 to 3, wherein the amount of asphalt is 1 to 50 parts by mass with respect to 100 parts by mass of the contaminated solid containing the halogenated organic compound.

[0006]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention is a simple treatment method for decomposing harmful halogenated organic substances such as dioxins in contaminated solids containing halogenated organic compounds. Each component constituting the present invention will be described below. 1. Contaminated Solids Containing Halogenated Organic Compounds Contaminated solids containing halogenated organic compounds used in the present invention include dioxins, polychlorinated biphenyls (PCBs), fluorocarbons, chlorinated hydrocarbon solvents,
It is a substance containing halogenated organic compounds such as chlorinated hydrocarbon-based detergents. The substances include contaminated soil, refuse incineration ash, fly ash, molten fly ash, sludge, slag, coal ash (fly ash), Sludge and the like. In particular, substances containing dioxins are suitable targets. In addition,
When containing water, it is preferable to dry it before the treatment.

[0007] 2. Asphalt Asphalt includes, in addition to ordinary straight asphalt obtained from petroleum refining, solvent deasphalted aphalt produced by solvent extraction, natural asphalt, modified asphalt with rubber, regenerated asphalt, and the like. They may be used alone or in combination of two or more. As the physical properties, since the heat-treated product is desirably in a solid state at room temperature, a material having a penetration of 100 or less is preferable. The amount of the asphalt to be used is preferably 1 to 50 parts by mass based on 100 parts by mass of a contaminated solid (dry state) containing a halogenated organic compound.
Parts by mass, more preferably 5 to 30 parts by mass.
If the amount is too small, the effect of decomposing the halogenated organic compound may not be sufficient. If the amount is too large, asphalt having a small penetration easily becomes a fluid state, which is not preferable.

[0008] 3. Alkali metal compound As the alkali metal compound, hydroxides such as caustic soda and caustic potash and carbonates such as sodium carbonate and potassium carbonate are preferably used. They may be used alone or in combination of two or more. The amount used depends on the amount of the halogenated organic compound in the contaminated solid containing the halogenated organic compound, but is preferably at least 10 times the mole of the halogenated organic compound. In the case of contaminated soil, the TEQ conversion value is at most 10 ng TEQ / g, and the amount of dioxin is about 1,000 ng / g or less. I just need. If the soil is acidic, an additional amount is required to neutralize it. In the case of fly ash, it is 100 ng / g at most, so it is sufficient that the amount is 0.1 part by mass or more based on 100 parts by mass of fly ash (dry state).
If the amount of the alkali metal compound is too small, the effect of decomposing the halogenated organic compound may not be sufficient.

In the present invention, the contaminated solid containing the halogenated organic compound is heated and kneaded together with the asphalt and the alkali metal compound. The kneading temperature is preferably 200 ° C. or more, more preferably 250 to 450 ° C. preferable. If the kneading temperature is too low, the effect of decomposing the halogenated organic compound may not be sufficient. The kneading time is preferably 0.1 to 4 hours. If the time is too short,
In some cases, the effect of decomposing the halogenated organic compound is not sufficient. If the effect is too long, the effect corresponding to the time cannot be obtained, which may be economically disadvantageous.

For the heat kneading, a conventional kneader used for kneading and mixing a powder and a liquid can be used, and examples thereof include wheel-type, blade-type, and roll-type kneaders.
After heating and kneading, the solidification occurs in a few minutes even if left as it is, but a solidified product can be obtained quickly by cooling with air or water. The kneading can also be performed in an atmosphere of an inert gas such as nitrogen. As described above, by heating and kneading the contaminated solid containing the halogenated organic compound together with the asphalt and the alkali metal compound, the harmful halogenated organic compound can be efficiently and easily decomposed.

The present invention is extremely effective as a treatment technology for detoxifying harmful halogenated organic compounds such as dioxin in incinerated ash, fly ash, molten fly ash, contaminated soil and other industrial wastes of municipal waste. . The stabilized solidified body that has been treated does not require post-treatment and can be used for landfill as it is, and can be used for civil engineering materials and the like.

[0012]

Next, the present invention will be described in detail with reference to examples, but the present invention is not limited to these examples. Reference Example 1 Dioxin-contaminated soil was 100
After drying at 12 ° C for 12 hours, pulverize in a mortar and divide with a sieve to 4 mm
A sample having the following particle size (hereinafter abbreviated as sample A) was obtained. The measurement of dioxins was performed according to the method for measuring dioxins in ash of the Ministry of Health and Welfare, and the amount of dioxins per 1 g of sample A was expressed as a toxic equivalent (ngTEQ).
As a result, the amount of dioxins in Sample A was 2.3 ng.
TEQ / g.

[Example 1] 100 g of sample A and 25 g of A80 grade straight asphalt (penetration 72) were heated to 250 ° C. and heated at a rate of 30 revolutions per minute while heating a 100 cc heating type biaxial kneader. It was added in small portions. To this, 4 g of caustic soda (powder) was added and kneaded. After 15 minutes, the mixture was cooled to room temperature to obtain a solid. The amount of dioxins in the solidified product was 0.38 ng TEQ / g, and the amount of dioxins could be reduced to 1 ng TEQ / g or less (tentative reference value for soil).

Example 2 A heating type biaxial kneader having a capacity of 100 cc was heated to 250 ° C. and rotated at 30 revolutions per minute while a small amount of 100 g of sample A and 15 g of propane deasphalted asphalt (penetration degree 5) were added. Were added one by one. To this, 4 g of caustic soda (powder) was added and kneaded. After 15 minutes, the mixture was cooled to room temperature to obtain a solid. The amount of dioxins in the solidified product was 0.36 ng TEQ / g, and the amount of dioxins could be reduced to 1 ng TEQ / g or less (tentative reference value for soil).

Example 3 A 100 g sample A and 15 g A80 grade straight asphalt (penetration 72) were heated while heating a biaxial kneader having a capacity of 100 cc at 250 ° C. and rotating at 30 rpm. It was added in small portions. To this, 5.6 g of potassium hydroxide (powder) was added and kneaded. After 15 minutes, the mixture was cooled to room temperature to obtain a solid. The amount of dioxins in this solidified product was 0.46 ng TEQ / g, and the amount of dioxins could be reduced to 1 ng TEQ / g or less (tentative reference value for soil).

Example 4 A 100 g sample A and 5 g of A80 grade straight asphalt (penetration 72) were heated at 250 ° C. and heated at a rate of 30 revolutions per minute by heating a 100 cc heating type biaxial kneader. It was added in small portions. To this, add 4 g of caustic soda (powder) and knead,
After 15 minutes, the mixture was cooled to room temperature to obtain a solid. The amount of dioxins in this solidified product was 0.71 ng TEQ / g, and the amount of dioxins could be reduced to 1 ng TEQ / g or less (tentative reference value for soil).

Example 5 A 100 g sample A and 15 g A80 grade straight asphalt (penetration 72) were heated at 350 ° C. in a heating type biaxial kneader having a capacity of 100 cc and rotated at 30 rpm. It was added in small portions. To this, 4 g of caustic soda (powder) was added and kneaded. After 15 minutes, the mixture was cooled to room temperature to obtain a solid. The amount of dioxins in this solidified body was 0.18 ng TEQ / g, and the amount of dioxins could be reduced to 1 ng TEQ / g or less (tentative reference value for soil).

Comparative Example 1 A 100 g sample A and 4 g caustic soda (powder) were heated at 250 ° C. in a heating type biaxial kneader having a capacity of 100 cc and rotated at 30 rpm.
Was added and kneaded, and cooled to room temperature after 15 minutes to obtain a solid. The amount of dioxins in this solidified product is 2.4 ngT
EQ / g, and no decomposition of dioxins was observed.

[0019]

According to the present invention, harmful halogenated organic compounds such as dioxins in contaminated solids containing halogenated organic compounds can be efficiently decomposed by a simple treatment method, The post-treatment can be landfilled without any need for post-treatment. Thus, the present invention is extremely significant in terms of preventing environmental pollution.

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Claims (4)

[Claims] 1. A treatment of a contaminated solid containing a halogenated organic compound, wherein the contaminated solid containing the halogenated organic compound is heated and kneaded together with asphalt and an alkali metal compound to decompose the halogenated organic compound. Method. 2. The method for treating contaminated solid matter containing a halogenated organic compound according to claim 1, wherein the mixture is heated and kneaded at 200 ° C. or higher. 3. The method for treating contaminated solid matter containing a halogenated organic compound according to claim 1, wherein the asphalt has a penetration of 100 or less. 4. The amount of asphalt is from 1 to 5 based on 100 parts by mass of a contaminated solid containing a halogenated organic compound.
The method for treating contaminated solid matter containing a halogenated organic compound according to any one of claims 1 to 3, which is 0 parts by mass.