Contaminated soil treatment

Abstract

To provide a contaminated soil treatment device that is compact in size and can efficiently treat contaminated soil without causing excess waste.SOLUTION: A contaminated soil treatment device has: a furnace 11 that has fluidizing means and fluidizes continuously supplied contaminated soil while bringing it into contact with hot air supplied from a hot air generator 25 and discharges the heated contaminated soil; and a dust collector 41 that traps solid in exhaust containing the hot air, discharged from the furnace 11. The solid contains contaminated soil and dust derived from the contaminated soil. The furnace 11 is in communication with the dust collector 41. The exhaust is directly sent from the furnace 11 to the dust collector 41.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a device for treating contaminated soil.

Background Art

[0002] The purification method of radioactive cesium-contaminated soil (hereinafter referred to as contaminated soil) can be roughly classified into a wet treatment method and a dry treatment method. As the wet treatment method, for example, contaminated soil is put into a wet sieve, gravel and coarse sand with a particle size exceeding 2 mm are recovered, and then the remaining soil with a particle size of 2 mm or less is applied to a hydrocyclone (centrifugal separator), and reclassified into soil with a particle size of 0.063 to 2 mm and concentrated contaminated soil with a particle size of 0.063 mm or less. The soil with a particle size of 0.063 to 2 mm is recovered by effectively peeling off the cesium adhesion part by scrubbing treatment.

[0003] As the dry treatment method, for example, calcium chloride is added to contaminated soil, and these are heated to 900 °C or higher to volatilize radioactive cesium, and a method of obtaining soil with a reduced content of radioactive cesium is available (see, for example, Patent Document 1).

[0004] There is also a treatment method in which after drying contaminated soil with a stirring dryer, the dried contaminated soil is crushed with an impact crusher, and the crushed soil is classified with an air classifier to isolate fine-grained soil (see, for example, Patent Document 2).

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0006] Wet treatment methods generate turbid water (wastewater), requiring wastewater treatment facilities to process this wastewater. The treatment method described in Patent Document 1 belongs to the heat treatment method within the dry treatment methods, and while it does not have the problem of wastewater treatment, it consumes a lot of energy and has high treatment costs.

[0007] The processing method described in Patent Document 2 recovers decontaminated soil through drying, crushing, and classification operations, with each operation performed by a separate, dedicated device. While such a processing method is easy to operate and control, it requires a device for transporting the contaminated soil from one device to another. This contaminated soil transport device also requires measures to prevent the contaminated soil from scattering during transport. For this reason, the processing equipment that implements the processing method described in Patent Document 2 requires a large number of devices, is large in scale, and is therefore expensive.

[0008] The objective of the present invention is to provide a contaminated soil treatment device that is compact and can efficiently treat contaminated soil without generating excess waste. [Means for solving the problem]

[0009] The present invention relates to a contaminated soil treatment apparatus for purifying contaminated soil by dry-classifying the contaminated soil and separating soil with high contamination concentrations, comprising: a heating furnace equipped with a fluidizing means that rotates to fluidize the contaminated soil, which is continuously supplied and fluidized while being brought into contact with hot air supplied from a hot air generating means, drying the contaminated soil and performing wind-power classification, and discharging contaminated soil of a set particle size; a dust collector that collects solid matter in the exhaust gas discharged from the heating furnace, including the hot air; a contaminated soil supply device that supplies contaminated soil to the heating furnace; and a control means that controls the hot air generating means, the fluidizing means, and the contaminated soil supply device, wherein the solid matter includes a portion of the contaminated soil and dust originating from the contaminated soil, the heating furnace and the dust collector are in communication, and the exhaust gas is directly supplied from the heating furnace to the dust collector. , The control means controls one or more of the following: the amount of hot air, the rotation speed of the fluidizing means, and the amount of contaminated soil supplied, so that the temperature and particle size of the contaminated soil discharged from the heating furnace are set to values. At this timeThis contaminated soil treatment device is characterized by controlling one or more of the following: the amount of hot air, the rotation speed of the fluidizing means, and the amount of contaminated soil supplied, so that fuel consumption is minimized and / or the amount of contaminated soil supplied is maximized.

[0010] The contaminated soil treatment apparatus according to the present invention is characterized in that the contaminated soil continuously supplied to the heating furnace contains organic matter, and the solid contains the organic matter and solid components originating from the organic matter.

[0011] In the contaminated soil treatment apparatus according to the present invention, the dust collection apparatus is characterized in that two or more or two or more types of dust collection apparatus are arranged in series and are capable of classifying solids in the exhaust gas.

[0012] In the contaminated soil treatment apparatus according to the present invention, the fluidizing means is characterized by fluidizing the supplied contaminated soil so that the surface of the soil is polished.

[0013] The contaminated soil treatment apparatus according to the present invention is characterized in that the heating furnace is an internal combustion type rotary kiln.

[0014] In the contaminated soil treatment apparatus according to the present invention, the rotary kiln is equipped with a scraping means for scraping up the contaminated soil, and the scraping means is a part of the fluidization means.

[0017] The contaminated soil treatment apparatus according to the present invention includes the heating furnace, To adjust the gas flow rate inside the heating furnace The invention is characterized by comprising a gas supply means that supplies at least a portion of the exhaust gas from which air and / or the solids have been removed, wherein the air and / or exhaust gas supplied through the gas supply means is mixed with the hot air and comes into contact with the contaminated soil, and the control means controls the gas supply means and controls the gas flow rate in the heating furnace so that the particle size of the contaminated soil discharged from the heating furnace becomes a set value.

[0018] In the contaminated soil treatment apparatus according to the present invention, the control meansIt is provided with a reference database in which the properties of contaminated soil, operating conditions, and classification results obtained in advance are stored. By referring to the reference database, one or more of the hot air volume, Rotation speed of the fluidizing means and the supply amount of contaminated soil are controlled, or one or more of the hot air volume, Rotation speed of the fluidizing means the supply amount of contaminated soil, the supply amount of air and / or exhaust gas are controlled.

[0019] In the contaminated soil treatment apparatus according to the present invention, the properties of the contaminated soil include particle size distribution, water content, type and content of organic substances, and the operating conditions include hot air volume, flow the rotation speed of the automation means, and the supply amount of contaminated soil, or the hot air volume, flow the rotation speed of the automation means, the supply amount of contaminated soil, the supply amount of air and / or exhaust gas are included, and the classification result includes an evaluation value. The control means refers to the reference database and controls one or more of the hot air volume and the supply amount of contaminated soil so that the evaluation value becomes maximum according to the properties of the contaminated soil, or Rotation speed of the fluidizing means controls one or more of the hot air volume, Rotation speed of the fluidizing means the supply amount of contaminated soil, the supply amount of air and / or exhaust gas.

Advantages of the Invention

[0020] According to the present invention, it is possible to provide a contaminated soil treatment apparatus that is compact and can efficiently treat contaminated soil without generating excess waste.

Brief Description of the Drawings

[0021] [Figure 1] It is a configuration diagram of a contaminated soil treatment apparatus 1 according to the first embodiment of the present invention. [Figure 2] It is a configuration diagram of a contaminated soil treatment apparatus 2 according to the second embodiment of the present invention. [Figure 3] It is a functional configuration diagram of an operation control device 81 used in the contaminated soil treatment apparatus 2 according to the second embodiment of the present invention. <s>0000096< / s><s>0000097< / s>It is a flowchart showing a control procedure of an operation control device 81 used in the contaminated soil treatment apparatus 2 according to the second embodiment of the present invention. Note: There seems to be an issue with the tags and [Figure 4] as they are marked as <s> in the output which might be an error in the original input or the translation process. They are left as is in the translation based on the instructions. [Figure 5] This figure shows the configuration of the reference database of the operation control device 81 used in the contaminated soil treatment apparatus 2 of the second embodiment of the present invention. [Figure 6] This is a diagram showing the configuration of a contaminated soil treatment apparatus 3, which is a modified example of the contaminated soil treatment apparatus of the second embodiment of the present invention. [Figure 7] This figure shows the configuration of a dust collection device that can be used in the contaminated soil treatment device of the present invention. [Figure 8] This figure shows the configuration of the test apparatus used in the test described in Example 1 of the present invention. [Figure 9] This figure shows the configuration of the test apparatus used in the test described in Example 2 of the present invention. [Figure 10] This figure shows the results of a preliminary test of Example 2 of the present invention, relating to the water content. [Figure 11] This figure shows the results of a preliminary test of Example 2 of the present invention, relating to the particle size distribution. [Figure 12] This figure shows the results of a preliminary test of Example 2 of the present invention, relating to the particle size distribution. [Figure 13] This figure shows the results of a preliminary test of Example 2 of the present invention, relating to soil components. [Figure 14] This figure shows the results of a preliminary test of Example 2 of the present invention, relating to the fine particle content. [Figure 15] This figure shows the results of a preliminary test of Example 2 of the present invention, relating to the particle size distribution. [Figure 16] This figure shows the results of a preliminary test of Example 2 of the present invention, relating to the particle size distribution. [Figure 17] This figure shows the results of a preliminary test of Example 2 of the present invention, relating to the amount of organic matter. [Figure 18] This figure shows the results of a preliminary test of Example 2 of the present invention, relating the mass ratio to the fine particle removal rate and the coarse particle mixing rate. [Figure 19] This figure shows the results of a preliminary test of Example 2 of the present invention, illustrating the relationship between the fine particle removal rate and the organic matter removal rate. [Figure 20]This figure shows the results of a preliminary test of Example 2 of the present invention, relating the static pressure of the dryer to the mass ratio of the fine particles. [Figure 21] This figure shows the results of a preliminary test of Example 2 of the present invention, illustrating the relationship between airflow and the mass ratio of the fine particles. [Figure 22] This figure shows the results of a demonstration test of Example 2 of the present invention, relating to the water content. [Figure 23] This figure shows the results of a demonstration test of Example 2 of the present invention, relating to the particle size distribution. [Figure 24] This figure shows the results of a demonstration test of Example 2 of the present invention, relating to the particle size distribution. [Figure 25] This figure shows the results of a demonstration test of Example 2 of the present invention, relating to soil components. [Figure 26] This figure shows the results of a demonstration test of Example 2 of the present invention, relating to the fine particle content. [Figure 27] This figure shows the results of a demonstration test of Example 2 of the present invention, relating to the particle size distribution. [Figure 28] This figure shows the results of a demonstration test of Example 2 of the present invention, relating to the particle size distribution. [Figure 29] This figure shows the results of a demonstration test of Example 2 of the present invention, relating to the amount of organic matter. [Figure 30] This figure shows the results of a demonstration test of Example 2 of the present invention, relating the mass ratio to the fine particle removal rate and the coarse particle mixing rate. [Figure 31] This figure shows the results of a demonstration test of Example 2 of the present invention, illustrating the relationship between the fine particle removal rate and the organic matter removal rate. [Figure 32] This figure shows the results of a demonstration test of Example 2 of the present invention, relating to the radioactive Cs concentration. [Figure 33] This figure shows the results of a demonstration test of Example 2 of the present invention, relating to the decontamination rate. [Figure 34] This figure shows the results of a demonstration test of Example 2 of the present invention, illustrating the relationship between the fine particle removal rate and the decontamination rate. [Modes for carrying out the invention]

[0022] Figure 1(A) is a diagram showing the configuration of the contaminated soil treatment device 1 according to the first embodiment of the present invention, and Figure 1(B) is a diagram schematically showing the flow state of contaminated soil in the heating furnace 11. The contaminated soil treatment device 1 purifies contaminated soil by drying it in a heating furnace, further dry classifying the contaminated soil, and separating soil with high contamination concentrations. It includes a heating furnace 11 that brings the supplied contaminated soil into contact with hot air, a contaminated soil supply device 31 that supplies contaminated soil to the heating furnace 11, a dust collector 41 that collects solids in the exhaust gas discharged from the heating furnace 11, and an exhaust fan 61.

[0023] The contaminated soil to be treated is not particularly limited, but typically it is soil to which radioactive materials, heavy metals, dioxins, PCBs, pesticides, and persistent organic pollutants (POPs) have adhered, adsorbed, or attached. Examples of radioactive materials include cesium (Cs), plutonium (Pu), uranium (U), and radium (Ra). The contaminated soil may contain moisture and organic matter such as plants, leaves, wood chips, and root hairs. The contaminated soil may also contain lumpy material, but even such contaminated soil can basically be treated without pretreatment.

[0024] The heating furnace 11 is an internal combustion rotary kiln 11, comprising a kiln body 12, a drive device 21 for rotating the kiln body 12, and a hot air generator 25 for supplying hot air to the kiln body 12. The heating furnace 11 liquefies the contaminated soil continuously supplied by the contaminated soil supply device 31 while bringing it into contact with the hot air supplied by the hot air generator 25. The heating furnace 11 can be any device that can liquefy the contaminated soil continuously supplied by the contaminated soil supply device 31 while bringing it into contact with the hot air supplied by the hot air generator 25, for example, a horizontal agitator equipped with a hot air generator. The internal combustion rotary kiln 11 is preferred as the heating furnace 11 because it can be easily made large and is relatively inexpensive.

[0025] The kiln body 12 is rotatably supported by the drive unit 21, with its inlet slightly higher than its outlet and slightly inclined from the inlet to the outlet. The kiln body 12 is cylindrical, and multiple scraping blades 13 for scraping up contaminated soil are mounted inside in a circular direction. The scraping blades 13 are fixed to the kiln body 12 and rotate integrally with the kiln body 12.

[0026] The shape and structure of the stirring blades 13 are not particularly limited, but it is preferable that they stir up and agitate the contaminated soil in a way that increases the contact area with the hot air. For example, it is preferable that they lift the contaminated soil to a high position and drop it inside the kiln body 12. Furthermore, it is preferable that the kiln body 12 and the stirring blades 13 fluidize the contaminated soil so that the surface of the contaminated soil particles is polished.

[0027] The inlet end of the kiln body 12 is covered by a cover 15 that is airtightly attached to the kiln body 12. On the other hand, the outlet end of the kiln body 12 is covered by a hood 16 that is airtightly attached to the kiln body 12. The cover 15 and the hood 16 are fixed in place. Here, the inlet is the side to which contaminated soil is supplied.

[0028] A discharge device 18 for discharging contaminated soil is attached to the bottom of the hood 16. In this embodiment, a rotary valve is shown as the discharge device 18, but the discharge device 18 is not limited to this. Since the kiln body 12 is under negative pressure, the discharge device 18 should be one that can discharge the contaminated soil while being sealed to the kiln body 12. An exhaust port 19 for exhaust gas is also provided at the top of the hood 16.

[0029] The heating furnace 11 functions not only as a dryer for drying the supplied contaminated soil, but also as a wind classifier. In the heating furnace 11, the gas (exhaust gas), mainly hot air supplied from the hot air generator 25, acts to classify the contaminated soil. Increasing the gas flow velocity inside the kiln body 12 increases the amount of solid (contaminated soil) contained in the exhaust gas discharged from the exhaust port 19, decreases the amount of contaminated soil discharged from the discharge device 18, and increases the average particle size.

[0030] The heating furnace 11 determines the gas flow rate inside the kiln body 12 and the size of the kiln body 12 so that the particle size of the contaminated soil (discharged soil) discharged from the discharge device 18 becomes a predetermined particle size (hereinafter referred to as the classification point) based on the set supply amount and properties of the contaminated soil. The properties of the contaminated soil include particle size distribution, moisture content, type of organic matter, and organic matter content.

[0031] The drive unit 21 rotatably supports the kiln body 12 and rotates the kiln body 12 in a direction that allows the scraping blades 13 to scrape up the contaminated soil. Preferably, the drive unit 21 has a variable rotation speed for the kiln body 12. The drive unit 21 rotates the kiln body 12 so that the contaminated soil is sufficiently scraped up inside the kiln body 12, the contaminated soil is sufficiently fluidized, and the surface of the contaminated soil particles is polished.

[0032] The hot air generator 25 is installed on the inlet side of the kiln body 12 and directly sends the hot air generated by burning fuel into the kiln body 12. In this embodiment, the heating furnace 11 has a parallel flow in which the direction of movement of the hot air is parallel to the direction of movement of the contaminated soil, but it may also be a cross flow in which the direction of movement of the hot air and the direction of movement of the contaminated soil are opposite.

[0033] The kiln body 12 is equipped with a pressure detector 27 for detecting the pressure at the inlet and a temperature detector 28 for detecting the temperature of the contaminated soil at the outlet inside the kiln body 12, and is connected to a pressure controller 67 and a temperature controller 65, respectively. The pressure controller 67 adjusts the opening of the electric damper 62 so that the pressure at the inlet of the kiln body 12 becomes a preset pressure. The temperature controller 65 adjusts the hot air generator 25 so that the temperature of the contaminated soil at the outlet becomes a preset temperature.

[0034] The contaminated soil supply device 31 is a device that supplies a fixed amount of contaminated soil to the heating furnace 11, and comprises a screw feeder 33 equipped with a hopper 32 and a supply pipe 34 connecting the screw feeder 33 and the heating furnace 11. In addition to a screw feeder, other types of soil supply devices such as table feeders may be used as the contaminated soil supply device 31. The contaminated soil supply device 31 is preferably capable of supplying a fixed amount of contaminated soil and can material seal regardless of the supply speed.

[0035] Since the contaminated soil supply device 31 communicates with the heating furnace 11 via the supply pipe 34, if a material seal is not formed, air will leak into the heating furnace 11 through the contaminated soil supply device 31 when negative pressure is created inside the heating furnace 11. Even if a complete material seal is not formed and air leaks in, it is preferable that the amount of air leaking in does not fluctuate with the amount of contaminated soil supplied. If the amount of air leaking into the heating furnace 11 fluctuates with the amount of contaminated soil supplied, operation and control become difficult.

[0036] The dust collector 41 is connected to the exhaust port 19 of the heating furnace 11 and collects solids contained in the exhaust gas discharged from the heating furnace 11. The main component of the exhaust gas discharged from the heating furnace 11 is the hot air supplied from the hot air generator after heating the contaminated soil, and it also contains water vapor resulting from the moisture contained in the contaminated soil and air leaking into the kiln body 12. The solids contained in the exhaust gas are small particles of the contaminated soil, polished contaminated soil generated in the kiln body 12, dust, organic matter contained in the supplied contaminated soil, crushed organic matter, carbonized material, and ashed material.

[0037] The dust collector 41 is composed of three types of dry dust collectors with different particle sizes for collection. In this embodiment, the baffle-type dust collector 43, which is an inertial-type dust collector, the cyclone 45, which is a centrifugal-type dust collector, and the bag filter 47, which is a filtration-type dust collector, are arranged in series in the order that the particle size for collection decreases from upstream to downstream.

[0038] The baffle-type dust collector 43, cyclone 45, and bag filter 47 used here are specified to correspond to the particle size to be collected, but the devices themselves are no different from known dust collectors. The baffle-type dust collector 43, cyclone 45, and bag filter 47 are each equipped with discharge devices 44, 46, and 48 for discharging the collected solids. In this case, the discharge devices 44, 46, and 48 are rotary valves.

[0039] The exhaust fan 61 is installed downstream of the bag filter 47 and is connected to the heating furnace 11 via the dust collector 41. An electrically operated damper 62 for adjusting the exhaust volume is provided in the pipeline connecting the exhaust fan 61 and the bag filter 47.

[0040] The operation procedure and effects of the contaminated soil treatment device 1 will be explained. The contaminated soil, which is continuously supplied from the contaminated soil supply device 31 to the heating furnace 11, is agitated and stirred up as it moves from the inlet to the outlet inside the kiln body 12, and is heated by contact with the supplied hot air. The temperature and pressure inside the kiln body 12 are controlled to predetermined levels via the temperature controller 65 and the pressure controller 67.

[0041] Specifically, the amount of hot air generated is adjusted so that the temperature detected by the temperature detector 28 reaches the set temperature T0. Note that the amount of hot air generated can also be referred to as the amount of hot air supplied or the amount of hot air. Temperature T0 is the minimum temperature at which the supplied contaminated soil dries sufficiently, or the minimum temperature + α (a margin). It is preferable to determine temperature T0 through preliminary tests or similar methods.

[0042] The pressure controller 67 also adjusts the exhaust air volume so that the pressure detected by the pressure detector 27 becomes the set pressure P0. Pressure P0 is atmospheric pressure or slightly lower than atmospheric pressure at the inlet side of the kiln body 12. By making the inlet pressure inside the kiln body 12 atmospheric pressure or slightly lower than atmospheric pressure, it is possible to prevent contaminated soil from being ejected from the kiln body 12 to the outside.

[0043] The drive unit 21 rotates the kiln body 12 at a predetermined rotational speed N0. Rotational speed N0 is the speed at which the contaminated soil is sufficiently scraped up inside the kiln body 12, the contaminated soil is sufficiently fluidized, and the surface of the contaminated soil particles is polished. It is preferable to determine this rotational speed N0 by conducting preliminary tests or the like.

[0044] The contaminated soil containing moisture is dried in the heating furnace 11, and a portion of the heated and dried contaminated soil (discharged soil) flows from the end of the kiln body 12 into the hood 16 and is continuously discharged via the discharge device 18. The remaining contaminated soil is carried along with the exhaust gas and sent to the dust collector 41 from the exhaust port 19. The solids contained in the exhaust gas are filtered by the baffle-type dust collector 43, cyclone 45, and bag filter 47, and are continuously discharged via discharge devices 44, 46, and 48. The particle size of the discharged solids decreases in the order of discharge device 18, discharge device 44, discharge device 46, and discharge device 48.

[0045] Since the contaminated soil treatment device 1 allows for variable control of the contaminated soil supply rate, hot air generation rate, and kiln rotation, these can be appropriately adjusted so that the discharged soil reaches the desired classification point.

[0046] Any lumpy material contained in the contaminated soil being supplied is crushed within the kiln body 12. Organic matter such as plants, leaves, wood chips, and root hairs contained in the contaminated soil is either kept in its original form, crushed and pulverized, or converted into carbonized or ashed material, which is then carried along with the exhaust gas and sent to the dust collector 41 where it is collected.

[0047] It is known that in soil on which radioactive cesium and other contaminants are fixed, adsorbed, or attached to the surface, the smaller the particle size, the higher the contamination concentration. When such contaminated soil is treated with the contaminated soil treatment device 1, the contaminated soil discharged from the discharge device 18 (discharged soil) has a low contamination concentration, while the contamination concentration of the solids discharged in the baffle-type dust collector 43, cyclone 45, and bag filter 47 increases in that order.

[0048] Thus, the contaminated soil treatment device 1 can separate and recover soil with different levels of contamination, enabling decontamination. Furthermore, the contaminated soil treatment device 1 uses a heating furnace 11 to fluidize the contaminated soil so that the surface of the contaminated soil particles is polished, allowing for the recovery of contaminated soil with a polished surface and a lower level of contamination.

[0049] As described above, the contaminated soil treatment device 1 can treat various types of contaminated soil, including soil containing moisture, lumps, and organic matter. Furthermore, because the heating furnace 11 and the dust collector 41 are directly connected, the exhaust gas discharged from the heating furnace 11 is directly guided to the dust collector 41, resulting in a compact device. These points are also true for the contaminated soil treatment devices 2 and 3 described later.

[0050] Figure 2 is a configuration diagram of the contaminated soil treatment apparatus 2 according to the second embodiment of the present invention. Figure 3 is a functional configuration diagram of the operation control device 81 used in the contaminated soil treatment apparatus 2, and Figure 4 is a flowchart of the control procedure of the operation control device 81. Components identical to those in the contaminated soil treatment apparatus 1 of the first embodiment shown in Figure 1 are denoted by the same reference numerals and their descriptions are omitted.

[0051] The contaminated soil treatment device 2 has the same basic configuration as the contaminated soil treatment device 1, but differs from the contaminated soil treatment device 1 in the following respects. Firstly, the contaminated soil treatment device 2 is equipped with an air supply device 71 that supplies air to the kiln body 12. In this embodiment, the air supply device 71 consists of an air supply valve 73 that adjusts the amount of air supplied and an air supply pipe 75 that connects the air supply valve 73 to the cover 15. The air supplied through the air supply device 71 is intended to increase the gas flow rate and gas velocity inside the kiln body 12, and this air is mixed with hot air and ultimately becomes exhaust gas.

[0052] Since the kiln body 12 is controlled by negative pressure, opening the air supply valve 73 draws outside air into the kiln body 12. If the pressure difference between the inside and outside of the kiln body 12 is small and a predetermined amount of air cannot be drawn in, a blower or forced-air fan can be installed upstream of the air supply valve 73.

[0053] Secondly, the contaminated soil treatment device 2 is equipped with an operation control device 81 that controls the operation of the contaminated soil treatment device 2. Similar to the contaminated soil treatment device 1 of the first embodiment, the contaminated soil treatment device 2 uses dry classification to separate contaminated soil into predetermined particle sizes and then separates and recovers them. In the contaminated soil treatment device 2, as in the contaminated soil treatment device 1, the gas flow rate inside the kiln body 12 basically determines the classification point. In other words, by controlling the gas flow rate inside the kiln body 12, the contaminated soil can be separated into desired particle sizes. In the contaminated soil treatment device 2 of this embodiment, in order to respond to contaminated soil with various properties, the operation control device 81 controls each device in accordance with the properties of the contaminated soil.

[0054] The operation control device 81 includes a data input means 83 capable of inputting data or receiving data signals, a storage means 85 for storing data and an operation control program 91, a control means 87 for controlling each means, and a data output means 89 capable of transmitting data signals. In the contaminated soil treatment device 1 of the first embodiment, a temperature controller 65 and a pressure controller 67 control the temperature and pressure inside the heating furnace 11 to predetermined levels, but in the contaminated soil treatment device 2, the operation control device 81 performs this role. For this reason, the contaminated soil treatment device 2 is not specifically provided with a temperature controller 65 or a pressure controller 67.

[0055] The control procedure for the operation control device 81 will now be explained. When data on the properties of contaminated soil is input via the data input means 83, the control means 87 reads the operation control program 91 stored in the storage means 85 and calculates the amount of contaminated soil to be supplied and the amount of hot air generated, etc., that are appropriate for the properties of the contaminated soil. The control means 87 transmits control signals via the data output means 89 to the contaminated soil supply device 31, the hot air generator 25, etc., so that the calculated amount of soil to be supplied and the amount of hot air generated, etc.

[0056] The specific calculation procedures for the amount of contaminated soil supplied and the amount of hot air generated will be explained. The operation control program 91 is given the gas flow velocity U0 in the kiln body 12 required for classification, the amount of hot air generated required to heat the contaminated soil containing water to temperature T0, and the residence time θ0 in the heating furnace 11 required to heat the contaminated soil containing water to temperature T0. The amount of hot air generated is given as a correlation formula or correlation data between the amount of contaminated soil supplied and the amount of hot air generated, for example, with the moisture content as a parameter. The gas flow velocity U0, temperature T0, residence time θ0, and amount of hot air generated are preferably obtained through preliminary tests, and the gas flow velocity U0 may have a range, such as gas flow velocity U0 ± β (micro-flow velocity).

[0057] When the operation control device 81 receives data on the properties of the contaminated soil via the data input means 83 (step S1), it calculates the amount of contaminated soil supplied F and the amount of hot air generated Q that satisfy the temperature T0 based on the correlation formula or correlation data between the amount of contaminated soil supplied and the amount of hot air generated (step S2). From the amount of contaminated soil supplied obtained in step S2, it selects the amount of contaminated soil supplied F and the corresponding amount of hot air generated Q that satisfy the residence time θ0 (step S3).

[0058] Next, the gas flow velocity U inside the kiln body 12 is calculated from the amount of hot air generated Q obtained in step S3 and the cross-sectional area (effective cross-sectional area) of the kiln body 12 (step S4), and it is determined whether the gas flow velocity U is within the range of gas flow velocity U0 (step S5). If the gas flow velocity U is within the range of gas flow velocity U0 in step S5, the kiln with the largest amount of contaminated soil supplied F is selected (step S6). This allows the contaminated soil to be treated under the conditions of the largest amount of contaminated soil supplied F and the smallest fuel consumption Q.

[0059] On the other hand, if the gas velocity U in step S5 is outside the range of gas velocity U0, air is supplied from the air supply device 71 so that the gas velocity U is within the range of gas velocity U0 (step S7). Along with the supply of air, it is determined whether the temperature T of the discharged contaminated soil detected by the temperature detector 28 is above or below temperature T0 (step S8). If the temperature T of the discharged contaminated soil is above or below temperature T0 in step S8, the control is performed according to the conditions of step S7 (step S9). On the other hand, if the temperature T of the discharged contaminated soil is below temperature T0 in step S8, the amount of hot air generated Q is increased and controlled so that the gas velocity U satisfies the gas velocity U0 and the temperature T satisfies the temperature T0 (step S10).

[0060] The rotation speed of the kiln body 12 is set to a speed at which the contaminated soil is sufficiently fluidized and shoveled up, and furthermore, the surface of the contaminated soil particles is polished. It is best to determine such a rotation speed by conducting preliminary tests. It is desirable for the surface of the contaminated soil particles to be polished, but it is undesirable for them to be crushed. Larger soil particles have a low concentration of contamination and become discharged soil, but if such particles are divided into two, they will be carried along with the exhaust gas and collected by the dust collector 41. This is the same in other embodiments as well.

[0061] In this embodiment, the contaminated soil treatment device 2 does not have soil transporting capabilities because the raking blades 13 do not have any effect on soil transport. Therefore, increasing or decreasing the rotation speed does not affect the residence time θ. However, since the kiln body 12 slopes downward towards the outlet, increasing the rotation speed of the kiln body 12 may shorten the residence time θ. It is advisable to conduct preliminary tests to determine in advance the relationship between the rotation speed N of the kiln body 12 and the residence time θ of the contaminated soil in the heating furnace 11, and to reflect this in the operation control. This is the same for other embodiments as well.

[0062] As a result, desired classification results can be obtained even for contaminated soils with different properties such as moisture content. Furthermore, since the contaminated soil can be processed under conditions that maximize the amount of contaminated soil supplied F and minimize fuel consumption Q, it is efficient and effective. When processing contaminated soils with different particle size distributions, a preliminary test should be conducted to calculate the gas flow velocity U0 suitable for classification, and the operating conditions should be calculated to satisfy this. The control procedure shown in Figure 4 is an example of an operating control method and is not limited to this.

[0063] Other control procedures for the operation control device 81 will be described below. The relationship between the properties of the contaminated soil, the operating conditions, and the classification results may be obtained in advance, a reference database linked together, and the operation may be controlled based on the selection of items from the reference database that match the properties of the contaminated soil. Figure 5 shows an example of the database configuration. The reference database is stored in the storage means 85.

[0064] In the reference database shown in Figure 5, the properties of the contaminated soil include particle size distribution, moisture content, type of organic matter, and organic matter content, while the operating conditions include the amount of contaminated soil supplied, the amount of hot air supplied, the amount of air supplied, and the rotation speed of the heating furnace 11. The distinction between particle size distribution PT1 to PT2 may be based on a predetermined particle size, such as a classification point, and the distinction may be based on the weight percentage of soil with a particle size smaller than or equal to that value. The classification between type of organic matter O0 to O2 may be, for example, O0 being soil with no organic matter, O1 being soil mainly containing leaves and wood chips, and O2 being soil mainly containing root hairs. In Figure 5, organic matter content OW0 indicates that the organic matter content is zero, and air supply amount AF0 indicates the case where no air is supplied from the air supply device 71.

[0065] In Figure 5, the evaluation values ​​Z1 to Z18 for the classification results are set higher for results that are closer to the desired classification result. For example, a predetermined particle size, such as the classification point, may be used as the basis, and the percentage of soil recovered with a particle size of 75 μm or less may be used as the evaluation value. For example, if the classification point is 75 μm, and the percentage of soil with a particle size of 75 μm or less in the supplied contaminated soil is 30 wt%, and the percentage of soil recovered by the dust collector 41 is 24 wt%, then the evaluation value would be 24 / 30 × 100 = 80. Note that in Figure 5, a higher number does not necessarily mean a higher evaluation value for evaluation values ​​Z1 to Z18.

[0066] The specific control procedure of the operation control device 81 will now be explained. When the operation control device 81 receives data on the properties of contaminated soil via the data input means 83, it reads from the reference database 85, selects operating conditions that match the properties of the contaminated soil, and controls each device based on these conditions. In this case, even if the properties of the contaminated soil only partially match, if there is only one operating condition selected, each device will be controlled under that condition.

[0067] If the properties of the contaminated soil only partially match and multiple operating conditions can be selected, the operating condition with the highest evaluation value will be selected, and each device will be controlled under that condition. If the properties of the contaminated soil do not match those of the contaminated soil listed in the reference database, the closest matching property will be selected, and each device will be controlled under that condition.

[0068] After treating the contaminated soil with the contaminated soil treatment device 2, it is advisable to add the data to a reference database. Accuracy improves as the data accumulates.

[0069] The operation control device 81 described above can be easily implemented using a known control device such as a programmable logic controller or a computer that stores the operation control program 91.

[0070] The contaminated soil treatment apparatus 2 of the second embodiment of the present invention is equipped with an operation control device 81 that controls each device, and can therefore be suitably used when treating various types of contaminated soil with different moisture content, particle size distribution, and types and amounts of organic matter. Furthermore, by using a reference database, it is possible to predict the classification results in advance, enabling efficient and effective classification.

[0071] Figure 6 is a configuration diagram of a contaminated soil treatment apparatus 3, which is a modified example of the contaminated soil treatment apparatus 2 of the second embodiment of the present invention. Components identical to those in the contaminated soil treatment apparatus 2 of the second embodiment shown in Figure 2 are denoted by the same reference numerals and their descriptions are omitted.

[0072] The contaminated soil treatment device 3 is designed to treat radioactively contaminated soil and includes a radiation concentration detector 30 installed at the bottom of the hood 16 to detect the radiation concentration of the discharged soil. The operation control device 81 controls each device so that the radiation concentration of the discharged soil reaches a preset concentration.

[0073] Since the radiation concentration in contaminated soil is higher for smaller particle sizes, if the radiation concentration of the discharged soil is higher than a predetermined concentration, the system is controlled to increase the particle size at the classification point. Specifically, the gas flow rate inside the kiln body 12 is controlled to increase so that the particle size of the solids contained in the exhaust gas increases.

[0074] The contaminated soil treatment device 3 can be used suitably for decontaminating radioactive soil because it can recover contaminated soil with a desired radiation concentration. Furthermore, by combining it with magnetization and magnetic separation technology for the decontaminated soil, it is possible to provide a more advanced decontamination and volume reduction treatment. The same applies to the contaminated soil treatment devices 1 and 2 of the first and second embodiments.

[0075] The contaminated soil treatment apparatus according to the present invention has been described above using the contaminated soil treatment apparatus 1 and 2 of the first and second embodiments, and the contaminated soil treatment apparatus 3 which is a modified example of the second embodiment. However, the contaminated soil treatment apparatus according to the present invention is not limited to the above embodiments and can be modified without changing the gist of the invention.

[0076] In the above embodiment, an example was shown in which three types of dust collectors with different collection principles are arranged in series as the dust collector 41, but it is not limited to this. The dust collector 41 should be arranged so as to efficiently collect solids according to the amount of exhaust gas, the concentration of solids contained in the exhaust gas, and the particle size of the solids.

[0077] Figure 7 shows the configuration of a dust collector that can be used in the contaminated soil treatment apparatus according to the present invention. When the solid concentration in the exhaust gas is low, one dust collector may be used as shown in Figure 7(A). When the particle size distribution of the solids in the exhaust gas is wide, four or five or more dust collectors of different types arranged in series can be suitably used as shown in Figure 7(B). Furthermore, when the amount of exhaust gas is large and the solid concentration in the exhaust gas is high, a configuration in which dust collectors are partially arranged in parallel as shown in Figure 7(C), or a configuration divided into two systems as shown in Figure 7(D), may be used.

[0078] In the second embodiment and its modified versions, the contaminated soil treatment apparatus 2 and 3, an air supply device 71 is provided for adjusting the gas flow rate U in the heating furnace 11. However, the contaminated soil treatment apparatus 1 of the first embodiment may also be equipped with an air supply device 71. Furthermore, in the contaminated soil treatment apparatus 1, 2, and 3, a gas supply means may be provided to supply a portion of the exhaust gas from which solids have been removed to the heating furnace 11, either in place of the air supply device 71 or together with the air supply device 71, as the gas for adjusting the gas flow rate U in the heating furnace 11.

[0079] In the above embodiment, a rotary kiln 11 is shown as the heating furnace 11, in which a hot air generator 25 is directly attached to the kiln body 12. However, the hot air generator 25 and the kiln body 12 may be separate. As long as a predetermined amount of hot air can be supplied to the heating furnace body, that is sufficient. This is also true when a device other than a rotary kiln is used as the heating furnace 11.

[0080] In the contaminated soil treatment devices 1, 2, and 3 described above, a weir that rotates together with the kiln body 12 may be provided at the outlet of the kiln body 12 in order to increase the residence time of the soil in the heating furnace 11. This weir can be provided by fixing a donut-shaped disc or the like to the outlet of the kiln body 12. Instead of providing a weir on the kiln body 12, a weir may be provided on the hood 16 at the outlet of the kiln body 12. A weir provided on the hood 16 does not rotate because it is separate from the kiln body 12. The weir provided on the hood 16 may be a movable weir with adjustable height. Such a weir can be easily formed from a plate.

[0081] Furthermore, in the contaminated soil treatment devices 1, 2, and 3 described above, a collision plate may be provided at the exhaust port 19 on the top of the hood 16 in order to prevent coarse particles from short-passing and mixing into the dust collection device 41. Also, in the contaminated soil treatment devices 1, 2, and 3 described above, a single damper, a double damper, a screw feeder (extractor), or a conveyor may be used as the discharge device 18.

[0082] In a contaminated soil treatment system, many variables (operating parameters) are involved in appropriately treating contaminated soil with different properties, as shown in Figure 5. Therefore, a reference database may be created by using preliminary test results as training data and applying machine learning to a learning model. In this case, it is preferable to add any newly obtained experimental data as training data.

[0083] While preferred embodiments have been described with reference to the drawings, those skilled in the art will readily anticipate various changes and modifications within the obvious scope upon reviewing this specification. Such changes and modifications will therefore be construed as falling within the scope of the invention as defined by the claims. Furthermore, the present invention is not limited to the embodiments described below. [Examples]

[0084] <Example 1> An internal combustion rotary kiln was used as the heating furnace, and a bag filter (BF) was used as the dust collection device. A quantitative supply of test soil was used to dry the sample soil and simultaneously perform air-based classification. The heating furnace was a Nikko Multi Dryer NMD-100 (outer diameter φ1,100 mm, length L3,500 mm, burner NTB-1S (combustion rate 20-49 L / h; fuel - kerosene), burner fan airflow 40.0 m³). 3 A motor (3.7kW, 2P, inverter) was used ( / min). A flowchart of the test setup is shown in Figure 8.

[0085] Commercially available decomposed granite soil was used for the test. Table 1 shows the physical properties of the decomposed granite soil used in the test. The natural moisture content of the test soil was 13.5%.

[0086] [Table 1]

[0087] Tests were conducted by varying the material supply rate, kiln air velocity, and kiln rotation speed to assess the drying state of the test soil and measure the discharge volume and particle size distribution of the samples collected in the discharge belt conveyor and bag filter. Air volume was calculated from the exhaust gas oxygen concentration at the exhaust chamber outlet, and kiln air velocity was calculated from the dryer hot air volume and the total exhaust gas volume.

[0088] Test Run5-1, Run5-2 Test soil was introduced into a rotary kiln at a rate of 1,000 kg / h, with a kiln rotation speed of 60 Hz, internal wind speeds of 0.52 m / s (Run 5-1) and 0.64 m / s (Run 5-2), and an exhaust gas temperature setting of 130°C for Run 5-1 and 180°C for Run 5-2. Wind force classification was then performed. The temperature of the test soil discharged from the discharge conveyor belt was 120°C for Run 5-1 and 165°C for Run 5-2. It has been confirmed that the test soil can be sufficiently dried, with a moisture content of approximately 1% or less, when heated to 112°C.

[0089] The test results showed that the fine particles recovered by the bag filter BF accounted for 6.3% of the total weight of the input soil in Run 5-1 and 7.7% in Run 5-2. The particle size composition (silt and clay content) of these fine particles was 86.1% (silt: 8.5%, clay: 17.6%) in Run 5-1 and 91.8% (silt: 74.3%, clay: 17.5%) in Run 5-2. These results indicate that by controlling the wind speed inside the kiln, the fine particles (silt and clay) can be selectively wind-classified. Furthermore, the proportion of silt increased compared to the untreated (raw) soil, confirming the grinding effect of the sand.

[0090] Test Run4-1, Run4-2 Test soil was fed into a rotary kiln at a rate of 500 kg / h, the kiln wind speed was set to 0.6 m / s, and wind classification was performed at kiln rotation speeds of 30 Hz (Run 4-1) and 15 Hz (Run 4-2). As a result, the fine-grained portion recovered by the bag filter (BF) accounted for 17.0% of the total weight of the input soil in Run 4-1 and Run 4-2. It was found that by reducing the kiln rotation speed (60 Hz → 30 Hz), the amount of soil held in the kiln and the amount of soil removed increased, allowing control over the amount of wind-classified soil sent to the bag filter (BF).

[0091] <Example 2> Figure 9 shows the test apparatus. This test apparatus is the same as the one shown in Figure 8 used in Example 1, but differs in the following two points. First, a fine / coarse particle partition wall is provided at the bottom of the bag filter to prevent fine particles from mixing with the coarse particle side when collecting the fine particles collected in the bag filter. Second, a mesh (foreign matter contamination prevention net) is provided at the top of the bag filter to prevent sand, gravel, etc. from accidentally mixing with the fine particle side.

[0092] The test procedure was basically the same as in Example 1, with the discharge from the kiln designated as the coarse-grained side or coarse-grained portion side, and the material collected in the back filter designated as the fine-grained side or fine-grained portion side. The coarse-grained side or coarse-grained portion side may be referred to as air separation (large), and the fine-grained side or fine-grained portion side may be referred to as air separation (small). "After treatment" has the same meaning as "after test," "after drying," and "after air classification."

[0093] The evaluation criteria for the test are as follows: (1) Removal of radioactive cesium Cs The decontamination rate was evaluated by reducing the radioactivity concentration of the coarse-grained soil after treatment relative to the radioactivity concentration of the test soil (before treatment). The formula for calculating the decontamination rate is as follows.

number

[0094] (2) Removal of fine particles and the amount of coarse particles contained in the fine particles after processing For fine-grained particles considered to have a high concentration of contamination, the amount of fine-grained particles in the test soil (before treatment) and the coarse-grained side after treatment was compared, and the removal rate was evaluated as the proportion of fine-grained particles removed. In addition, the wind classification was evaluated by the coarse-grained particle content, which is the proportion of coarse-grained particles in the fine-grained side after treatment. The evaluation formulas for each are as follows. Fine-grained particles consisted of silt (5-75 μm) and clay (less than 5 μm), and coarse-grained particles consisted of gravel (2 mm or more) and sand (75 μm-2 mm), and were calculated from the particle size distribution measurement results.

number

[0095] (3) Confirmation of changes in the amount of organic matter after treatment In wind-power classification, collecting organic matter on the fine-grained side is thought to contribute to a reduction in the contamination concentration of the coarse-grained portion by allowing radioactive substances attached to the organic matter to migrate to the fine-grained side. Furthermore, if the coarse-grained portion is to be recycled into construction materials, there are concerns about deterioration over time, such as the decomposition of organic matter contained in the coarse-grained portion. Therefore, it is desirable to remove as much organic matter as possible from the coarse-grained portion. Accordingly, the change in the amount of organic matter after treatment was evaluated as the organic matter removal rate, which is the ratio of the decrease in the amount of organic matter contained in the coarse-grained side after treatment compared to the amount of organic matter contained in the test soil (before treatment). The amount of organic matter was evaluated using the loss on ignition. The evaluation formula is as follows.

number

[0096] (4) Dryness evaluation (moisture ratio / moisture content) This process includes both classification and drying. Dryness was evaluated using either the moisture content ratio or the moisture content percentage. This paper primarily uses the moisture content ratio for evaluation. The formulas for calculating the moisture content ratio and moisture content percentage are as follows. Since this paper deals with dry soil, evaluation is performed using oven-dried dry soil.

number

[0097] The exam content is as follows: For the test soil, removed soil was used in the demonstration test, while simulated test soil was used in the preliminary test. The main specifications of the removed soil and simulated test soil are shown in Table 2. The simulated test soil is a soil that simulates the removed soil in terms of soil properties.

[0098] [Table 2]

[0099] Pre-examination conditions Table 3 shows the conditions (operating conditions) for the preliminary tests. In the main tests, the supply rate of simulated test soil (material supply rate, processing rate) was set to 800, 1000, and 1600 kg / h, the kiln static pressure was set to -30 and -100 Pa, the exhaust gas temperature was set to 130 and 150°C, and the kiln rotation speed was set to 6.7 and 13.4 rpm. Table 4 summarizes the test parameters for the operating conditions.

[0100] [Table 3]

[0101] [Table 4]

[0102] Results of the preliminary test Table 5 shows the test results conducted under the conditions shown in Table 3. Table 6 shows the estimated amount of water vapor generated from the simulated test soil and the amount of exhaust gas generated due to the consumption of burner fuel, using the results in Table 5. In Table 6, the "Before Input" column shows the water content of the simulated test soil, while the "Large," "Small," and "Average" columns after input show the water content of the coarse-grained side, the fine-grained side, and the average water content of the coarse-grained and fine-grained sides, respectively, after treatment.

[0103] [Table 5]

[0104] [Table 6]

[0105] The formula used to calculate the values ​​in Table 6 is shown below. The air ratio represents the ratio of the amount of excess air supplied to the burner to the theoretical amount of air required for complete combustion of the fuel supplied to the burner. The following formula was used. The O2 concentration used was an experimental value.

number

[0106] The water vapor generation rate (per unit time) indicates the amount of water vapor generated per unit time by the drying process on the soil introduced into the apparatus. As shown below, it was calculated by converting the moisture content in the soil to the volume of gaseous state. In equation (9), the treated soil moisture content ratio is the combined moisture content of the coarse-grained and fine-grained soil after treatment.

number

[0107] The combustion exhaust gas volume (per unit time) indicates the amount of exhaust gas generated per unit time by burning the fuel supplied to the burner. It was calculated using the following formula. Here, the combustion rate (per unit time) was measured. The theoretical dry amount and theoretical wet amount were values ​​used when kerosene was used as the fuel.

number

[0108] The total exhaust gas volume (per unit time) indicates the amount of exhaust gas generated per unit time from the test apparatus. The amount of exhaust gas generated from the test apparatus was evaluated as the sum of water vapor due to soil drying and exhaust gas from combustion. The calculation formula is shown below.

number

[0109] Verification of the mechanical properties of the test equipment The characteristics of the test apparatus, specifically the airflow generated within the apparatus, were evaluated using the estimated results shown in Table 6. The airflow generated within the apparatus was evaluated based on the assumption that there was no air inflow at the material discharge section and that the total exhaust gas volume and the airflow within the apparatus were equivalent. Furthermore, since the amount of water vapor generated within the total exhaust gas volume fluctuates depending on the water content of the test soil used, only the combustion exhaust gas volume was used in the evaluation of the airflow generated within the apparatus.

[0110] We confirmed that as the kiln's static pressure setting increases, the airflow supplied from the burner tends to increase. It should be noted that as the dryer's static pressure increases, the amount of air entering through gaps in the device's connections increases, leading to an increase in the airflow within the device—a common characteristic of drying equipment. A higher dryer static pressure value means a larger negative value (absolute value). We also confirmed that setting a higher exhaust gas temperature tends to increase the airflow within the device.

[0111] We confirmed that the airflow tends to increase as the amount of test soil supplied decreases. The decrease in combustion volume associated with the decrease in test soil supply is a normal trend for a drying device, as a decrease in the amount of material being processed leads to a decrease in burner combustion. On the other hand, we confirmed that the air-to-air ratio, determined from the O2 concentration in the exhaust gas, increases with the decrease in test soil supply. This is presumed to be because, as the burner combustion volume decreases, the balance between the amount of air entering through gaps in the device's connections and the amount of air leaking through gaps in the outlets changes, resulting in a change in the amount of exhaust gas inside the device and thus a change in airflow.

[0112] We confirmed that the airflow tends to increase with increasing kiln rotation speed. As the kiln rotation speed increases, the test soil inside the apparatus is lifted and dropped more frequently by the blades installed on the inner wall of the kiln, resulting in the formation of more bales. This promotes heat exchange between the hot air generated by the burner and the test soil, temporarily lowering the exhaust gas temperature. Therefore, it is thought that the burner opening increases, increasing the exhaust gas volume and thus the airflow, in order to eliminate the difference between the exhaust gas temperature and the exhaust gas set temperature.

[0113] Regarding water content The results for moisture content are shown in Figure 10. In the figure, P1 to P6 represent the test numbers, with "large air separation" representing the coarse grain side and "small air separation" representing the fine grain side. From the results in Figure 10, it can be seen that within the range of the test conditions, the moisture content was below 5% for both the fine grain side and the coarse grain side.

[0114] Regarding particle size distribution The particle size accumulation curves under each test condition are shown in Figures 11 and 12, the soil component distribution map is shown in Figure 13, and the fine particle content is shown in Figure 14. From these results, it can be seen that the soil is separated into coarse and fine particle sections.

[0115] Regarding the effects of kiln rotation The inner wall of the kiln is fitted with stirring blades, and as the kiln rotates, the soil inside is lifted and then dropped to the bottom of the kiln, a process that is repeated. This process is expected to have the effect of detaching and crushing fine particles adhering to the surface of the soil particles due to collisions between soil particles and with the wall surface. Therefore, the particle size distribution of the simulated test soil and the treated coarse and fine particles was evaluated. The results are shown as particle size volume curves in Figures 15 and 16. In the figures, large + small indicates the sum of the coarse and fine particles after treatment.

[0116] Examining the particle size volume curve, the combined total of coarse and fine particles after treatment, compared to the simulated test soil (original soil), generally shows an increase in fine particles. In particular, in test number P6, where the soil supply rate and kiln rotation speed were reduced, the increase in fine particles is clear (see Figure 16). This is thought to be due to the effects of the kiln's crushing and detachment.

[0117] Regarding the amount of organic matter Figure 17 shows the ignition loss results for each test condition. The overall trend shows that the ignition loss is higher on the finer-grained side than on the coarser-grained side. This indicates that organic matter migrated to the finer-grained side during this treatment. Note that the test apparatus was dried within a temperature range where combustion of organic matter did not occur.

[0118] Regarding fine particle removal rate, coarse particle mixing rate, and organic matter removal rate Table 7 shows the results for each test condition, including the removal rate of fine particles, the contamination rate of coarse particles, and the removal rate of organic matter.

[0119] [Table 7]

[0120] Figure 18 shows the results of evaluating the fine-grain removal rate and coarse-grain mixing rate, focusing on the proportion of fine-grained material. Since the proportion of fine-grained material in the test soil (raw soil) varies, the evaluation here was performed using the mass ratio, which is the value obtained by dividing the mass ratio of fine-grained material by the mass ratio of fine-grained material in the test soil (raw soil).

[0121] These results confirm a strong correlation between the mass percentage of the fine granules and the fine granule removal rate. To improve the fine granule removal rate, it is necessary to increase the mass percentage of the fine granules. On the other hand, since there is also a strong correlation between the mass percentage of the fine granules and the coarse granule inclusion rate, increasing the mass percentage of the fine granules will also result in unwanted material being mixed into the fine granules.

[0122] Figure 19 shows the relationship between the fine particle removal rate and the organic matter removal rate. A strong correlation is observed between the fine particle removal rate and the organic matter removal rate, confirming that the organic matter removal rate increases as the fine particle removal rate increases.

[0123] Relationship with mechanical properties Figure 20 shows the results of a summary of the changes in the mass ratio of the fine particles relative to the dryer static pressure, and the ratio of coarse particles to fine particles allocated to the fine particles. From Figure 20, it can be seen that as the value of the dryer static pressure increases in the negative direction, the mass ratio of the fine particles and the allocation ratio of fine particles tend to increase. However, the allocation ratio of coarse particles also increases.

[0124] Figure 21 shows the results of a summary of the relationship between airflow rate, the mass ratio of the fine particles, and the changes in the ratio of coarse to fine particles allocated to the fine particles. From Figure 21, it can be seen that as the airflow rate increases, the mass ratio of the fine particles and the allocation ratio of the fine particles decrease, but the allocation ratio of the coarse particles also tends to decrease. From these results, it is considered that the classification characteristics of thermal volume reduction air separation can be adjusted by setting the dryer static pressure to satisfy the set value for the mass ratio of the fine particles, and then adjusting the components contained in the fine particles by adjusting the airflow rate.

[0125] Demonstration test Table 8 shows the main specifications of the removed soil used in the demonstration test. In the demonstration test, the physical properties of each test soil were confirmed before the test was conducted.

[0126] [Table 8]

[0127] Test conditions for demonstration tests Table 9 shows the test conditions (operating conditions) using the removed soil. In this test, the supply rate of removed soil (material supply rate, processing rate) was 1000 kg / h, the kiln static pressure was set to -30 and -100 Pa, the exhaust gas temperature was set to 130 and 150 °C, and the kiln rotation speed was 6.7 and 13.4 rpm.

[0128] [Table 9]

[0129] Test results of the demonstration test Table 10 shows the results of tests conducted under the conditions shown in Table 9. Table 11 shows the estimated amount of water vapor generated from the removed soil and the amount of exhaust gas generated due to the burner's fuel consumption, based on the results in Table 10.

[0130] [Table 10]

[0131] [Table 11]

[0132] Regarding water content The results for the moisture content are shown in Figure 22. In the figure, "before," "middle," and "after" indicate the time when the sample was taken during the test. For W1 to W4, "before" was taken 20 minutes after the start, "middle" was taken 40 minutes after the start, and "after" was taken 60 minutes after the start. For W1', "before" was taken 10 minutes after the start, "middle" was taken 20 minutes after the start, and "after" was taken 30 minutes after the start. From the results in Figure 22, within the range of the test conditions, the moisture content was 3% or less for both the coarse-grained and fine-grained sides.

[0133] Regarding particle size distribution The results of the particle size accumulation curves are shown in Figures 23 and 24, the soil component distribution map is shown in Figure 25, and the fine particle content is shown in Figure 26. From these results, it can be seen that the soil is divided into coarse-grained and fine-grained components. Figures 23 and 24 use the average values ​​before, during, and after the analysis.

[0134] Regarding the effects of kiln rotation The particle size distribution of the actual decontaminated soil, and the particle size distribution of the combined coarse and fine particles after treatment, were evaluated using particle size sum curves. The evaluation was performed using the average of pre-treatment, mid-treatment, and post-treatment values. The results are shown in Figures 27 and 28.

[0135] Regarding the amount of organic matter The results of the ignition loss are shown in Figure 29. The overall trend shows that the ignition loss is higher on the finer-grained side than on the coarser-grained side. This indicates that organic matter migrated to the finer-grained side during this treatment. Note that the test apparatus was dried within a temperature range where combustion of organic matter did not occur.

[0136] Regarding fine particle removal rate, coarse particle mixing rate, and organic matter removal rate Table 12 shows the results for each test condition, including the removal rate of fine particles, the contamination rate of coarse particles, and the removal rate of organic matter.

[0137] [Table 12]

[0138] Figure 30 shows the results of evaluating the fine-grained portion removal rate and coarse-grained portion mixing rate, focusing on the proportion of fine-grained material. Since the proportion of fine-grained material in the test soil (removed soil) varies, the evaluation here was performed using the mass ratio, which is the value obtained by dividing the mass ratio of fine-grained material by the mass ratio of fine-grained material in the test soil (removed soil) by the mass ratio of fine-grained material.

[0139] These results confirm a strong correlation between the mass percentage of the fine granules and the fine granule removal rate. To improve the fine granule removal rate, it is necessary to increase the mass percentage of the fine granules. On the other hand, since there is also a strong correlation between the mass percentage of the fine granules and the coarse granule inclusion rate, increasing the mass percentage of the fine granules will also result in unwanted material being mixed into the fine granules.

[0140] Figure 31 shows the relationship between the fine particle removal rate and the organic matter removal rate. A strong correlation is observed between the fine particle removal rate and the organic matter removal rate, confirming that the organic matter removal rate increases as the fine particle removal rate increases.

[0141] Regarding radioactive Cs concentration In evaluating radioactivity levels, it is necessary to evaluate the soil in a dry state. Therefore, the radioactivity level of the dry soil was calculated using the following formula. The results are shown in the table as "without moisture". A summary of the evaluation results is shown in Table 13. Based on the contents of Table 13, the average value was calculated, and the results of the decontamination rate evaluation are shown in Table 14.

number

[0142] [Table 13]

[0143] [Table 14]

[0144] Figure 32 shows the results of the radioactive Cs concentration after treatment, Figure 33 shows the decontamination rate, and Figure 34 shows the relationship between the fine particle removal rate and the decontamination rate. From the results in Figure 32, it can be confirmed that the radioactive Cs concentration changes between the coarse particle side and the fine particle side, and that it tends to be generally higher on the fine particle side. Furthermore, as shown in Figure 34, a strong correlation is observed between the fine particle removal rate and the decontamination rate. From these results, it can be confirmed that the decontamination rate increases with increasing fine particle removal rate. Therefore, by removing the fine particles, low-concentration treatment can be performed efficiently. [Explanation of Symbols]

[0145] 1, 2, 3 Contaminated soil treatment equipment 11 Heating furnace 12 Kiln body 13 Kakiage wings 21 Drive unit 25. Hot air generator 30. Radiation concentration detector 31. Contaminated soil supply device 41 Dust collection device 43. Baffle-type dust collector 45 Cyclone 47 Bug Filter 61 Exhaust fan 71 Air supply device 81 Driving control device 91 Driving control program

Claims

1. A contaminated soil treatment device that purifies contaminated soil by dry-classifying the contaminated soil and separating the soil with high contamination levels, A heating furnace equipped with a fluidizing means that rotates to fluidize contaminated soil, which continuously supplies contaminated soil and brings it into contact with hot air supplied from a hot air generating means while fluidizing it, thereby drying the contaminated soil, classifying it by wind power, and discharging contaminated soil of a set particle size. A dust collector for collecting solids in the exhaust gas discharged from the heating furnace, including the hot air, A contaminated soil supply device that supplies contaminated soil to the aforementioned heating furnace, The hot air generating means, the fluidizing means, and the contaminated soil supply device are controlled by a control means, Equipped with, The solid comprises a portion of the contaminated soil and dust originating from the contaminated soil. The heating furnace and the dust collector are in communication, and the exhaust gas is sent directly from the heating furnace to the dust collector. The contaminated soil treatment apparatus is characterized in that the control means controls one or more of the hot air volume, the rotation speed of the fluidizing means, and the amount of contaminated soil supplied so that the temperature and particle size of the contaminated soil discharged from the heating furnace are set to values, and at the same time controls one or more of the hot air volume, the rotation speed of the fluidizing means, and the amount of contaminated soil supplied so that the fuel consumption is minimized and / or the amount of contaminated soil supplied is maximized.

2. The contaminated soil continuously supplied to the aforementioned heating furnace contains organic matter, The contaminated soil treatment apparatus according to claim 1, characterized in that the solid contains the organic matter and solid components originating from the organic matter.

3. The contaminated soil treatment apparatus according to claim 1 or 2, characterized in that the dust collection apparatus comprises two or more or two or more types of dust collection apparatus arranged in series, and is capable of classifying solids in the exhaust gas.

4. The contaminated soil treatment apparatus according to any one of claims 1 to 3, characterized in that the fluidizing means fluidizes the supplied contaminated soil so that the surface of the soil is polished.

5. The contaminated soil treatment apparatus according to any one of claims 1 to 4, characterized in that the heating furnace is an internal combustion rotary kiln.

6. The rotary kiln is equipped with a means for scooping up the contaminated soil, The contaminated soil treatment apparatus according to claim 5, characterized in that the aforementioned stirring means is part of the fluidizing means.

7. The heating furnace is provided with a gas supply means for supplying air and / or at least a portion of the exhaust gas from which the solid has been removed to adjust the gas flow rate inside the heating furnace. The air and / or exhaust gas supplied through the gas supply means is mixed with the hot air and comes into contact with the contaminated soil. The contaminated soil treatment apparatus according to any one of claims 1 to 6, characterized in that the control means controls the gas supply means and controls the gas flow rate in the heating furnace so that the particle size of the contaminated soil discharged from the heating furnace becomes a set value.

8. The control means includes a reference database in which previously acquired properties of contaminated soil, operating conditions, and classification results are stored. A contaminated soil treatment apparatus according to any one of claims 1 to 7, characterized in that it controls one or more of the following according to the properties of the contaminated soil, by referring to the aforementioned reference database: the amount of hot air, the rotation speed of the fluidizing means, and the amount of contaminated soil supplied, or controls one or more of the following: the amount of hot air, the rotation speed of the fluidizing means, the amount of contaminated soil supplied, and the amount of air and / or exhaust gas supplied.

9. The properties of the contaminated soil include particle size distribution, water content, and type and content of organic matter. The operating conditions include the amount of hot air, the rotation speed of the fluidizing means, and the amount of contaminated soil supplied, or the amount of hot air, the rotation speed of the fluidizing means, the amount of contaminated soil supplied, and the amount of air and / or exhaust gas supplied. The aforementioned classification results include an evaluation value. The contaminated soil treatment apparatus according to claim 8, characterized in that the control means refers to the reference database and controls one or more of the hot air volume, the rotation speed of the fluidizing means and the contaminated soil supply volume so that the evaluation value is maximized according to the properties of the contaminated soil, or controls one or more of the hot air volume, the rotation speed of the fluidizing means, the contaminated soil supply volume, and the supply volume of air and / or exhaust gas.

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