JP2008272539A - Method and apparatus for detoxifying dioxin polluted particle - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method and apparatus capable of always efficiently detoxifying pollutant of soil or the like polluted with dioxin up to a sufficient level. <P>SOLUTION: Particles polluted with dioxin are classified by a method including the mutual rubbing of the particles or the contact with a moving fluid (S1-S3). A particulate sample collected at the same place is trially classified in advance to measure the concentration of dioxin at every particle size and, on the basis of the measuring result, a set particle size is determined. The particles with the set particle size or below in the classified particles are chemically treated to detoxify dioxin (S5-S8) and the particles exceeding the set particle size are not chemically treated (S4). <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The invention which concerns on a claim is related with the method and apparatus for detoxifying the granular material, such as soil contaminated with dioxins.

  Contamination of soil and the like with dioxins may become a problem in the vicinity of factory sites, waste disposal facilities, or illegal dumping sites.

About the method of detoxifying the contaminant by dioxins, there are description in the following patent documents 1-3. The method described in Patent Document 1 is a method in which a contaminant containing an organic chlorine compound such as dioxins is dried and pulverized, and a detoxifying chemical is added and heat-treated. The thing of patent document 2 is a method of wash | cleaning a comparatively low concentration contaminated soil with hot water, and isolate | separating muddy water from soil. In the technique of Patent Document 3, a contaminated soil or powder is slurried with water, foreign matter such as pebbles and iron pieces is removed by wet classification (classification using water), and the slurry is heated to dioxins. Is to be decomposed.
JP 2004-174372 A JP 2002-86129 A JP 2004-8872 A

  The method described in Patent Document 1 is suitable for detoxifying contaminants caused by dioxins. However, if the entire amount of soil and the like is always treated according to them, it is efficient in terms of time and cost required for the treatment. May not be right. The method of Patent Document 2 is good when the dioxins are at a low concentration, but there is a possibility that the treatment cannot be performed to a sufficient level when the concentration is high. The method of Patent Document 3 is a method of removing foreign substances and increasing the efficiency of heating by removing sludge by slurrying the soil or the like. As with 1, there will be an efficiency problem.

  In consideration of the above points, the claimed invention provides a method and apparatus capable of detoxifying contaminants such as soil contaminated by dioxins efficiently and always to a sufficient level. It is.

The method of detoxifying the dioxin-contaminated powder particles described in the claim is:
1) Particles contaminated with dioxins are classified (separated according to particle size) by a method that involves rubbing particles or contacting with a moving fluid.
2) Dioxins are detoxified by heat-treating powder particles that are smaller than the set particle size (or less than the set particle size),
3) It is characterized in that heat treatment is not performed on the powder particles exceeding the set particle size (or larger than the set particle size) (after the above classification).
“Dioxins” refers to polychlorinated dibenzofurans, polychlorinated dibenzo-para-dioxins, and coplanar-polychlorinated biphenyls, that is, chemical substances stipulated in the Special Measures Countermeasures against Dioxins. “Powder and granular material” refers to those obtained by crushing and crushing soil and ash, as well as building waste materials and dumped materials, etc. In order to classify particles by a method involving friction between particles or contact with a moving fluid, so-called dry or wet (type using water) classification means (vibrating sieve, etc.) are used, respectively. Good. “Abrasion between powder particles or contact with moving fluid” means only the former (rubbing between particles), only the latter (contact with moving fluid), and the case where the former and the latter are combined It is.

According to the investigation by the inventors, dioxins adhering to large particles (eg, stone or large sand) among particles such as soil rub the surface of the particles or flush with water. Many are removed. For this reason, when the granular material is classified by the method as described in 1) above, most of the dioxins are removed from the large granular material in the classification process.
In the claimed invention, after appropriately determining the particle size (set particle size) as the boundary of classification, only those having a particle size equal to or less than the set particle size are heat-treated as in 2) above, while as in 3) above No heat treatment is performed for those exceeding the set particle size. This is because a particle having a particle size larger than the set particle size is sufficiently decontaminated (removing adhering contaminants by washing) in the classification process as described above to become a decontaminated product.
According to the present invention, the amount of the granular material subjected to the heat treatment for detoxification is reduced to increase the efficiency in treatment time and cost, and the detoxification is promoted to a sufficient level regardless of the contamination concentration. It becomes possible.

With regard to the method of the invention, classified powder particles exceeding the set particle size may be buried in the collection point of the powder particles (that is, in the original place or in the vicinity thereof).
This eliminates the work burden of carrying out the cleaned granular material, and if the powder is excavated soil, the work burden of arranging and carrying in the soil to backfill the excavation site is also included. It is reduced.

As a heat treatment for a granular material having a particle size equal to or smaller than a set particle size, it is preferable to perform a heat dechlorination treatment in a low oxygen atmosphere (indirect heating) in the vicinity of the sampling point of the granular material (that is, on-site). .
Here, the detoxification of the contaminated powder particles by dioxins can be appropriately realized using heat dechlorination treatment (Hagenmeier method). If such an appropriate detoxification process is performed on-site, there is no need to carry out pollutants, and there is an advantage that dioxins are not scattered during the carry-out. As described above, the powder particles subjected to the chemical treatment are limited to those having a set particle size or less as described above and are quantitatively reduced. Therefore, the burden on facilities and work associated with on-site heat treatment is small.

The set particle size described above is determined based on the measurement result after measuring and classifying the powder sample collected from the same sampling point as the powder and measuring the concentration of dioxins for each particle size (that is, dioxin). It is preferable to find the particle size of the boundary where a remarkable difference in the concentration of the compound is found and to use it as the set particle size).
The set particle size can also be determined according to actual results and experience. However, since the state of contamination often varies depending on the properties of the granular material (soil, etc.), it is most appropriate to determine it after conducting test classification in advance. When the set particle size is appropriate, the amount of chemical treatment for detoxification can be greatly reduced to increase efficiency, and the level of detoxification can be increased. In addition, prior test classification should be performed by a method involving friction between powder particles or contact with a moving fluid, similar to the above classification, but it is necessary to determine the set particle size from the difference in dioxin concentration for each particle size In addition, here, it is advantageous to perform the test classification so that the particle size can be divided into a larger number of particle sizes than in the classification.

If the objects to be treated include a large amount of building waste or dumped waste that is not granular, the classification process is the same as for soil, etc. It is possible to detoxify by the above method including
In the case where the object to be treated including the contaminated portion by dioxins is not a granular material, it is preferable to obtain the contaminated granular material by crushing it beforehand.

The detoxifying device for dioxins-contaminated powder particles described in the claims is a device for carrying out the detoxification method described above, and the powder is crushed by a method in which the powder particles are rubbed or contacted with a moving fluid. Means for classifying granules (for example, a dry or wet classifier including a vibrating screen) and means for heat-treating particles having a particle size equal to or smaller than a set particle size to detoxify dioxins (for example, an apparatus for the Hagenmeier method) ).
According to such a detoxifying device, it is possible to carry out the above detoxifying method and detoxify pollutants efficiently and at a high level.

The method for detoxifying dioxin-contaminated powder granules described in the claims reduces the amount of powder (soil, etc.) subjected to chemical treatment to improve efficiency in terms of treatment time and cost, and depends on the contamination concentration. It is possible to promote detoxification to a sufficient level. It is also possible to reduce the work burden for carrying out the granular material and the risk of scattering of dioxins.
In addition, according to the detoxification device for dioxins-contaminated granular materials described in the claims, the detoxification method described above can be carried out to detoxify contaminants efficiently and at a high level.

  1 to 6 show an embodiment of the invention. FIG. 1 is a flowchart showing a basic procedure for the detoxification method of the present invention, and FIGS. 2 and 3 are explanatory diagrams specifically showing the entire procedure in the case where the classification process is performed by a dry process and a wet process, respectively. FIG. 4 is a block diagram showing an outline of the configuration of the detoxifying means 3 that performs heat treatment. FIG. 5 and FIG. 6 are explanatory diagrams showing a flow when the test classification is performed by a dry method and a wet method, respectively.

The soil contaminated with dioxins (hereinafter referred to as “DXN”) can be detoxified by the procedure shown in FIG. That is,
First, when contaminated soil is received (S1), classification is performed by a dry or wet method (S2). By the classification, the original soil is divided into those having a size exceeding a predetermined set particle size and those having a size smaller than that (S3).
The soil (classified product) exceeding the set particle size is not subjected to special treatment thereafter as it has been washed (S4). In the case of dry classification, the powder particles rub against each other in a vibrating screen, and in the case of wet classification, the powder particles come into contact with running water, resulting in a large particle size exceeding the set particle size. This is because most of DXN should have been removed.
On the other hand, soil (classified product) having a particle size equal to or smaller than the set particle size is accepted as a contaminant that has not been removed (S5), dried and pulverized (S6), and the Hagenmeier (hereinafter referred to as “HM”) method. Detoxification treatment is performed (S7), and the soil from which most of DXN has been removed is defined (S8).

A specific flow in the case where the above classification process is performed by a dry method is as shown in FIG. Reference numerals S1 to S8 in the figure are associated with the processes in FIG.
As shown in Fig. 2, contaminated soil is first excavated and collected, placed in a flexible container (flexible transport bag), air-dried (indoor drying, etc.), and then transferred to a hopper for quantitative supply ( S1). At the excavation site, the soil (or other object to be treated) may be crushed into a granular form using an appropriate crushing means before being transferred to the hopper. The soil taken out from the hopper is divided into a size exceeding the set particle size (15 mm in the example of FIG. 2) and the other size by vibration sieve (S2 · S3), and the soil exceeding the set particle size is sieved ( It is backfilled in the excavation site as a processed product removed during classification) (S4). Those below the set particle size classified by the vibration sieve are further finely pulverized (with a particle diameter of 2 mm or less in the example of FIG. 2) by a pulverizer such as a vibro mill and the second vibration sieve, and supplied to the silo as contaminants. (S5). The dry classification means 1 is constituted by the above-mentioned vibrating screen, a grinding device such as a vibro mill, and the second vibrating screen.
Soil that is considered to be uncontaminated soil whose size is less than the set particle size is taken out from the supplied silo, dried and crushed (S6), and sent to the detoxification equipment by the HM method. A heat treatment for decomposing DXN is performed (S7) to make a detoxified product (S8). The exhaust gas generated during the drying and the detoxification treatment is also treated at the same time, and the detoxification treatment means 3 is constituted by the detoxification treatment equipment, peripheral equipment and exhaust gas treatment equipment.

The flow in the case where the classification process is performed by a wet process is illustrated in FIG. Also in this figure, reference numerals S1 to S8 are entered in association with the process in FIG.
In the case of FIG. 3, the contaminated soil is excavated and collected, transferred from the flexible container to the hopper (S1), passed through a washing screen together with industrial water and passed through a wet vibrating screen, and the set particle size (2 mm in the example of FIG. 3) is set. Separate the ones that exceed the size and the others (S2, S3). In addition, those exceeding the set particle diameter are backfilled in the excavation site as treated products removed in the classification process (S4). Soil having a particle size equal to or smaller than the set particle size that passes through the mesh of the vibration sieve is sent to the raw water tank together with water as a contaminant that has not been removed, and is agglomerated and settled to separate water (drainage) and soil (sludge). Water is filtered and stored in the treated water tank, while the soil is put into a dewatered sludge silo through a dehydrator and supplied to a transport system including a pump (S5). The wet classifying means 2 is constituted by the illustrated cleaning screen, vibrating screen, raw water tank / coagulation tank / sedimentation tank / dehydrator.
As in the case of FIG. 2, the soil as a contaminant is dried and pulverized (S6), then sent to a detoxification device using the HM method, and subjected to a heat treatment for decomposing DXN in the soil (S7). (S8). The detoxification processing means 3 is composed of the detoxification processing equipment, its peripheral equipment and equipment for exhaust gas treatment.

  The configuration and processing steps of the detoxification processing means 3 used in the flow of FIGS. 2 and 3 are as shown in FIG. That is, rotary kilns (heating drums) 3C are connected to the ends of feeders 3A and 3B that quantitatively supply soil and the like, and nitrogen gas is supplied to these to make the inside of the atmosphere low in oxygen. The soil, etc. (solid) exiting the rotary kiln 3C is supplied to the cooler 3D and further sent to the cooling storage tank 3E for storage, while the gas generated in the rotary kiln 3C is sent to the gas cooling tower 3F for cooling and filled with activated carbon. Exhaust after passing through tank 3G.

  In the flow of FIG. 1, in order to determine whether the soil classification is performed by a dry method as shown in FIG. 2 or wet as shown in FIG. 3 and to determine a set particle size (ie, sieve size), Dry and wet test classifications shown in FIGS. 5 and 6 are performed using soil samples collected in advance from the excavation site of the contaminated soil.

  In the dry test classification shown in FIG. 5, the sample is air dried and, for example, a test classifier 11 (electromagnetic type) having sieves (mesh) of 2 mm, 0.85 mm, 0.425 mm, 0.25 mm, and 0.075 mm. (A collection of vibration sieves 11A, 11B, 11C, 11D, and 11E). The particle size classification in the test classification, that is, the number of sieves and the size of the eyes is not limited to this, but in this example, the soil sample is a gravel with a particle size exceeding 2 mm and a particle size exceeding 0.85 mm. Coarse sand 1 of 2 mm or less, Coarse sand 2 of particle size exceeding 0.425 mm and 0.85 mm or less, Fine sand 1 exceeding particle size of 0.25 mm and 0.425 mm or less, and particle size 0 It is divided into fine sand 2 exceeding 0.075 mm and not more than 0.25 mm and clay having a particle diameter of not more than 0.075 mm.

  In the wet test classification shown in FIG. 6, the sample is passed through a drum washer and a trommel together with washing water, the gravel having a particle size of 5 mm or more is removed and rubbed with a sand scrubber, and then wet test classifier in a state containing water. Classify at 12. The test classifier 12 is also an aggregate of electromagnetic vibration sieves 12A, 12B, 12C, 12D, and 12E having screens of 2 mm, 0.85 mm, 0.425 mm, 0.25 mm, and 0.075 mm, for example. By using this, the soil sample is divided into gravel and coarse sand 1, coarse sand 2, fine sand 1, fine sand 2, and clay, as in the test classification of FIG. The clay (having a particle size of 0.075 mm or less) that has passed through the test classifier 12E having the finest sieve is coagulated and precipitated, and then dehydrated as sludge and recovered as a dehydrated cake.

  Whether the soil to be collected is suitable for dry or wet classification is determined by performing the test classification shown in FIGS. 5 and 6 together. For example, if the dry test classification cannot adequately separate the small particle size because the soil is agglomerated and difficult to loosen, it is based on the wet classification. Further, how much the set particle size is determined is determined by measuring the concentration of DXN for each particle size classification screened in the above test classification. The particle size of the boundary where a significant difference in density is found is taken as the set particle size.

  An example of detoxification of the soil subjected to simulated contamination by DXN and detoxification by the method of the invention will be introduced below. In this example, wet classification is performed, and after setting the set particle size by test classification performed in advance, classification is performed at the set particle size and detoxification treatment (heat treatment by HM method) is performed on a part of the soil. It was given.

  First, Table 1 shows the results of wet test classification. The measured value about the weight according to the particle size of soil and DXN density | concentration is shown. From these values, it was judged that DXN concentration was reduced for processed products exceeding 0.075 mm (test classification treatment was performed. These dry weights were 68% of the total), and they were sufficiently washed. . On the other hand, since a reduction in DXN concentration was not observed in treated products of 0.075 mm or less (dry weight was 32% of the total), it was judged that they need chemical treatment as contaminants. However, in Table 1, the sum of the dry weights for each particle size recovered without including work loss was 100%.

  Based on the results of the above test classification, wet classification was performed on 150 kg of DXN simulated contaminated soil, and the weight of each soil particle size was measured. The results are shown in Table 2. The amount of the processed material exceeding 0.075 mm (namely, the washed product) was about 63% of the total amount before classification, and the amount of the processed material (namely, contamination) equal to or less than 0.075 mm was about 32%. However, in Table 2, the work loss was 5%. Since heat treatment is performed only on the latter, the number of heat treatment objects can be reduced to one-third of the whole.

  The treated product (contaminated matter) having a wet classification of 0.075 mm or less was detoxified by the HM method. Table 3 shows the DXN concentration measured for the treated soil. The removal rate of DXN by the detoxification treatment was 99.6% according to the bioassay, and 99.9% according to the official method.

  In this embodiment, the chemical detoxification treatment is performed after wet classification. However, the same procedure can be applied to dry classification instead of wet classification.

It is a flowchart which shows a basic procedure about the detoxification method of the dioxin contamination granular material by invention. It is explanatory drawing which shows specifically the whole procedure in the case of performing a classification process by a dry type among the detoxification methods of invention. It is explanatory drawing which shows specifically the whole procedure in the case of performing a classification process by wet among the detoxification methods of invention. It is a flowchart which shows the outline of a structure about the means which aims at detoxification by heat processing. It is explanatory drawing which shows the flow in the case of performing prior test classification by a dry type. It is explanatory drawing which shows the flow in the case of performing prior test classification by wet.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Dry classification means 2 Wet classification means 3 Detoxification treatment means 11 Dry type test classifier 12 Wet test classifier

Claims (6)

Classifying powders contaminated with dioxins by a method involving rubbing of the powders or contact with a moving fluid,
Dioxins-contaminated powder, characterized by chemical treatment of powder particles smaller than the set particle size to detoxify dioxins and no chemical treatment of particles larger than the set particle size How to detoxify your body.   2. The method for detoxifying dioxin-contaminated powder particles according to claim 1, wherein classified powder particles exceeding a set particle diameter are buried in the collection points of the powder particles.   3. A heat dechlorination treatment (Hagenmeier method) in which heating is performed in a low-oxygen atmosphere as a heat treatment for a granular material having a particle size equal to or smaller than a set particle diameter is performed at a sampling location of the granular material. Detoxification method for dioxin-contaminated powder particles described in 1.   A granular sample collected from the same location as the granular material is subjected to test classification in advance, and the concentration of dioxins for each particle size is measured, and the set particle size is determined based on the measurement result. The detoxification method of the dioxin contamination granular material as described in any one of Claims 1-3.   The dioxin-contaminated granular material according to any one of claims 1 to 4, wherein the contaminated granular material is obtained by crushing an object to be treated containing a contaminated portion by dioxins in advance. Detoxification method. An apparatus for carrying out the detoxification method for dioxins-contaminated powder particles according to any one of claims 1 to 5,
Means for classifying powder particles by a method involving friction between particles or contact with a moving fluid; Means for chemically treating powder particles having a set particle size or less to detoxify dioxins An apparatus for detoxifying dioxin-contaminated powder particles, comprising:

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