KR20210141429A - Method for purification of radioactive contaminated soil - Google Patents

Abstract

Disclosed is a method for purifying radioactive contaminated soil. The method for purifying radioactive contaminated soil according to an embodiment of the present invention includes: a crushing/washing step of performing a washing process after crushing soil contaminated with a radioactive material; a soil selecting step of separating soil having a large particle size from the soil by size after the crushing/washing step and selecting soil having a small particle size to process the soil as soil waste; and a purifying step of processing the soil separated in the soil selecting step to generate purified soil and a purified waste solution.

Description

Method for purification of radioactive contaminated soil

The present invention relates to a method for purifying radioactively contaminated soil for selecting and removing radioactive substances from soil contaminated with radioactive substances for purifying soil contaminated with radioactive substances.

In the wake of the Fukushima nuclear accident caused by the Great East Japan Earthquake in March 2011, the number of countries choosing to phase out nuclear power is gradually increasing. In line with the global trend, Korea is also pursuing a policy to phase out nuclear power, such as abolishing new nuclear power plant construction plans and suspending the lifespan extension of old nuclear power plants. When a nuclear power plant is dismantled, a large amount of radioactively contaminated soil is generated. Therefore, in Korea, the need for a technology for effectively purifying contaminated soil according to the dismantling of a nuclear power plant is emerging.

In addition, clay among soil components is selectively and irreversibly bound to radioactive materials, making it difficult to purify, whereas soil with large particle sizes such as sand and gravel has a low contamination distribution and is relatively easy to purify. The need for a technology to reduce the amount of soil waste by selectively separating highly polluted clay, which accounts for 30%, is also emerging.

However, the conventional method for purifying radioactively contaminated soil is about a method of purifying radioactively contaminated soil through a detergent without considering the size of soil particles, and since it does not go through a selection process according to the size of soil particles, the amount of soil waste is significantly increased. There was a problem being

In addition, in particular, in the case of cesium (Cs) or cobalt (Co), since it has a strong bond with clay, the efficiency of soil purification and purification is low with the prior art, or a separate high-temperature process is required, which significantly increases the treatment cost. , there was also a problem in that re-contamination by the discarded magnetic adsorbent or the like occurs.

Registered Patent Publication No. 10-1265255 (2013. 05. 16. Announcement)

Therefore, the present invention has been proposed to solve the above problems, and the problem to be solved by the present invention is to efficiently treat a large amount of radioactive soil generated during a nuclear power accident or dismantling of a nuclear power plant, thereby reducing the amount of radioactive soil waste and treating it. It is aimed at reducing costs and suppressing secondary waste generation.

In order to achieve the object of the present invention as described above, the present invention is a crushing/washing step of performing a washing process after crushing the soil contaminated with radioactive material; a soil selection step of separating soil having a large particle size from the soil after the crushing/washing step by size, selecting selected soil having a small particle size, and treating it as soil waste; and a purification step of processing the soil separated in the soil selection step to generate purified soil and a purified waste solution;

In addition, the crushing and washing step is a crushing step of crushing radioactive contaminated soil; and a washing step of washing the soil after the crushing step.

In addition, the washing step is a cleaning agent input step of spraying the cleaning agent to the crushed contaminated soil after the crushing step; and a stirring step of stirring the crushed contaminated soil.

In addition, the cleaning agent input step preferably includes a step of evenly dispersing the soil agglomerates and the cleaning agent by applying ultrasonic energy to the ultrasonic dispersing device.

In addition, the soil selection step may include a first separation step of separating and removing soil having a diameter of 2 mm or more from the soil after the crushing/washing step; a second separation step of separating soil having a diameter of 0.2 mm or more from the soil after the first separation step; a fine soil separation step of separating soil having a diameter of 0.1 mm or more from the soil after the second separation step; and a highly selective separation step of separating soil with a diameter of 0.04 mm or more after the fine soil separation step.

In addition, in the first separation step, it is preferable to separate soil with a diameter of 2 mm or more using a screen sorting device.

In addition, in the second separation step, it is preferable to perform a high-pressure fluidization process by introducing a magnetic adsorbent, and perform a sieve separation process after the high-pressure fluidization process is performed.

In addition, in the fine soil selection step, it is preferable to wet-separate soil with a diameter of 0.1 mm or more from the soil by applying a hydrocyclone technology.

In addition, the fine soil selection step separates the solution from the solution containing the soil separated after applying the hydrocyclone technology and selectively removes nuclides in the generated waste solution in the first separation step or the second separation step It is desirable to perform solid/liquid separation and waste-liquid treatment processes so that they can be reused.

In addition, the high-level screening and separation step selects soil with a diameter of less than 0.4 mm by magnetic force-based high-level screening technology, and the magnetic-based high-level screening technology is a selective magnetization technology for selectively attaching cationic magnetic nanoparticles to the soil; and a magnetic-soil complex magnetic selection technology for separating the soil to which the cationic magnetic nanoparticles are attached.

In addition, the highly selective separation step is the first separation step or the second separation by separating the solution from the solution containing the soil separated after application of the magnetic-soil complex magnetic screening technology and selectively removing nuclides in the generated waste solution. It is preferable to perform a solid/liquid separation and waste liquid treatment process so that it can be reused in the step.

In addition, the purification step may include a pollution level measurement step of measuring the level of pollution of the soil separated in the soil selection step; a soil washing step of separating the waste solution by purifying the soil whose contamination level is determined to be greater than or equal to the reference value in the contamination level measurement step; and a waste liquid treatment step of treating the waste liquid separated in the soil washing step.

In addition, in the step of measuring the degree of pollution, it is preferable to classify the soil whose pollution level is found to be less than the reference value as purified soil.

In addition, it is preferable to perform the contamination level measurement step on the soil from which the waste liquid is separated after the soil washing step.

In addition, the waste liquid treatment step may include a floating component separation step of separating an oil component or a suspended matter from the waste liquid; a major nuclide removal step of removing at least one nuclide selected from the group consisting of cesium, strontium, iodine, etc. after the suspended component separation step; Residual nuclide removal step of removing residual nuclide in the waste solution after the main nuclide removal step; and a fine particle removal step of removing fine particles in the waste solution after the residual nuclide removal step.

According to an embodiment of the present invention, the soil can be separated according to particle size and the most efficient purification treatment method can be applied for each particle size, so that the purification effect is excellent and inefficient waste of purification resources can be prevented.

In addition, it is possible to minimize the volume of radioactive waste by limiting the range so that the soil to be disposed of because it is economically impossible to purify is soil having a minimum particle size.

In addition, since the magnetic adsorbent input in the purification process is magnetically recovered and reused, the cost associated with the purification process can be reduced and secondary contamination problems caused by the disposal of the magnetic adsorbent can be prevented.

1 is a table showing characteristics of each particle size of soil.
2 is a block diagram schematically illustrating a method for purifying radioactively contaminated soil according to an embodiment of the present invention.
3 is a configuration diagram schematically illustrating a system for implementing a method for purifying radioactively contaminated soil according to an embodiment of the present invention.
4 is a block diagram schematically illustrating the crushing and washing steps of the method for purifying radioactively contaminated soil according to an embodiment of the present invention.
5 is a view showing an attrition scrubber according to an embodiment of the present invention.
6 is a block diagram schematically illustrating a soil selection step in a method for purifying radioactively contaminated soil according to an embodiment of the present invention.
7 schematically illustrates a trommel screen according to an embodiment of the present invention.
8 schematically shows a system in which a high-pressure fluidization process is performed according to an embodiment of the present invention.
9 schematically shows a system in which hydrocyclone technology is performed according to an embodiment of the present invention.
10 shows that a plurality of systems are provided in which the hydrocyclone technique of FIG. 9 is performed.
11 shows a magnetic-soil complex formation process according to an embodiment of the present invention.
12 is a magnetic field according to an embodiment of the present invention - shows a magnetic force selection technology of the soil complex.
13 is a block diagram schematically illustrating a waste liquid treatment step according to an embodiment of the present invention.

Hereinafter, with reference to the accompanying drawings, the embodiments of the present invention will be described in detail so that those of ordinary skill in the art to which the present invention pertains can easily implement them. The present invention is not limited to the embodiments disclosed below, but may be implemented in a variety of different forms, and only these embodiments allow the disclosure of the present invention to be complete, and common knowledge in the technical field to which the present invention belongs It is provided to fully inform the possessor of the scope of the invention. In order to clearly explain the present invention in the drawings, parts irrelevant to the description are omitted, and the same reference numerals are used for the same or similar elements throughout the specification. In addition, the terminology used herein is for the purpose of describing the embodiments, and is not intended to limit the present invention. In this specification, the singular form also includes the plural form as the case may be, unless otherwise specified in the phrase. As used herein, “comprises” and/or “comprising” does not exclude the presence or addition of one or more other components than the stated components. Unless otherwise defined, all terms used herein may be used with meanings commonly understood by those of ordinary skill in the art to which the present invention pertains. In addition, terms defined in general used dictionary are not to be interpreted ideally or excessively unless clearly specifically defined. Other advantages and features of the present invention, and methods of achieving them, will become apparent with reference to the embodiments described below in detail in conjunction with the accompanying drawings.

1 is a table showing characteristics of each particle size of soil. "Size (mm)" in FIG. 1 means the diameter of the particle.

In soil, the degree of contamination of nuclides, surface area, surface charge, and cation adsorption capacity vary depending on the particle size. In general, since particles of various sizes are mixed in soil, a separate purification process according to the size of the particles is required to efficiently purify the radioactively contaminated soil. In particular, soils with large particle sizes such as sand and gravel have a low contamination distribution and are relatively easy to purify even when contaminated. It is irreversibly bound and difficult to purify.

In addition, in soil, clay, silt, organic matter, iron oxide, etc. are physically and chemically combined to form an aggregate, and contaminants including radionuclides are mainly present in the form of adsorption or sedimentation on the aggregated particles, so efficient soil decontamination is achieved. For this, the agglomeration of the soil is very important.

Therefore, the embodiment of the present invention described below is a method for efficiently dispersing the particle size of radioactively contaminated soil, performing a separate purification process according to the particle size of the soil, and selectively separating and purifying particles with a small diameter, such as clay with a high degree of contamination. and the provision of the system will be described.

2 is a block diagram schematically showing a radioactively contaminated soil purification method according to an embodiment of the present invention, and FIG. 3 is a configuration schematically illustrating a system for implementing a radioactively contaminated soil purification method according to an embodiment of the present invention. It is also

The method for purifying radioactively contaminated soil according to an embodiment of the present invention includes a crushing/washing step (S10), a soil selection step (S20) and a purification step (S30).

In the crushing/washing step (S10), a washing process is performed after crushing the soil contaminated with a radioactive material.

4 is a block diagram schematically illustrating the crushing/washing step (S10).

The crushing/washing step (S10) includes a crushing step (S11) and a washing step (S12).

In the crushing step (S11), the contaminated soil is crushed. The crushing of the contaminated soil is preferably performed with an appropriate strength enough to separate the aggregated soil into individual particles such as gravel, sand, silt, and clay. In the crushing step (S11), a crusher may be used. The crusher may be a device that crushes the soil by applying a physical force. In addition, the crusher may be a device for crushing soil using ultrasonic waves. When the contaminated soil is crushed, the surface area of the contaminated soil particles is widened, thereby increasing the efficiency of the washing step (S12).

In the washing step (S12), the soil crushed in the crushing step (S11) is washed. In the washing step (S12), it is possible to wash the radioactive material of the contaminated soil using a cleaning agent. When the crushing step (S11) proceeds, most of the radioactive materials contaminated with gravel, sand, etc. may be purified. In addition, some of the radioactive material contaminated with silt, clay, etc. can also be purified. The washing step (S12) may include a washing agent input step (S121) and a stirring step (S122).

In the cleaning agent input step (S121), the cleaning agent is sprayed on the crushed soil after the crushing step (S11). The cleaning agent can purify most of the radioactive material contaminated with gravel and sand and some of the radioactive material contaminated with silt and clay. The cleaning agent sprayed on the contaminated soil is preferably _{sodium bicarbonate (NaHCO 3 ).} For example, if described with respect to the action of sodium bicarbonate (NaHCO _3), if of a typical uranium of radioactive sodium bicarbonate (NaHCO ₃₎ and when the reaction of sodium bicarbonate (NaHCO ₃₎ the molecular uranium oxide in bimolecular reaction or bicarbonate One molecule of uranium oxide reacts with three molecules of sodium (NaHCO _{3 ) to form a complex.} When the complex thus formed is separated and removed, radioactive contaminants such as uranium adsorbed on the surface of the particles of the contaminated soil are washed.

Conventionally, a strong acid solution has been used as a cleaning agent, but the strong acid solution has a high possibility of safety accidents and may reduce the durability of peripheral devices when used for a long period of time. In addition, there is a problem in that a separate process for neutralizing the acid is required, thereby complicating the process and increasing the cost. Therefore, using sodium bicarbonate (NaHCO ₃ ) as a cleaning agent can solve these problems.

In the cleaning agent input step (S121), an ultrasonic dispersing device may be used. The ultrasonic dispersing device may separate the aggregates of the soil by applying ultrasonic energy. When ultrasonic energy is applied by the ultrasonic dispersing device, the dispersion efficiency is increased, the injected cleaning agent is evenly dispersed, and the contaminant dissolution effect by the cleaning agent is increased. When the ultrasonic dispersing device is used together with the Attrition Scrubber (1) described below, it has been experimentally confirmed that the dispersion efficiency is improved by about 7-8%.

Figure 5 shows an attrition scrubber that can be used in the stirring step (S10).

In the stirring step (S122), the contaminated soil is stirred so that the added cleaning agent can be evenly dispersed in the contaminated soil. Attrition scrubber (Attrition Scrubber, 1) may be used for agitation of contaminated soil. When the Attrition Scrubber (1) is applied, the dispersion efficiency is increased, the cleaning agent is dispersed evenly, and the effect of dissolving contaminants by the cleaning agent can be increased. When the attrition scrubber (1) is applied alone, the dispersion efficiency increases by about 2-3%, and as described above, when the ultrasonic dispersion device is simultaneously applied, the dispersion efficiency increases by about 7-8%. confirmed experimentally.

Attrition scrubber (Attrition Scrubber, 1) is connected to the input port (5) to put the contaminated soil, the stirrer (3) to stir the contaminated soil, the motor (2) to rotate the stirrer, the motor (2) and the stirrer (3) To include a rotary shaft (4) for transmitting power and an outlet (6) for discharging contaminated soil. The stirrer 3 is preferably rotated at a speed of 100 to 200 rpm. If the rotation speed of the stirrer 3 is lower than 100 rpm, stirring may not be sufficient. If the rotation speed of the agitator 3 is higher than 200 rpm, the contaminated soil may come out through the outlet 6 without being properly stirred.

The cleaning agent input step (S121) and the stirring step (S122) may be started at the same time, and the stirring step (S122) may be performed first and the cleaning agent input step (S121) may be performed while the soil is stirred.

6 is a block diagram schematically illustrating a soil selection step (S20).

In the soil selection step (S20), the soil having a large particle size is separated by size from the soil crushed and washed in the crushing/washing step (S10), and the soil having a small particle size is selected (selected soil) and treated as soil waste. Referring to FIG. 6 , the soil selection step ( S20 ) includes a first separation step ( S21 ), a second separation step ( S23 ), a fine soil selection step ( S25 ), and a complex formation step ( S27 ).

In the first separation step (S21), the soil having a diameter of 2 mm or more, such as gravel, is separated from the soil that has undergone the crushing/washing step (S10).

7 schematically shows a trommel screen that can be used in the first separation step S21.

In the first separation step (S21), for example, the soil with a diameter of 2 mm or more may be separated through the screen sorting device 10 such as a trommel screen as shown in FIG. 8 . Soil with a diameter of 2 mm or more, such as separated gravel, can be disposed of as it is without going through a separate treatment process because the degree of nuclides contamination is low. The screen sorting device 10 includes an input hopper 11 , a screen unit 13 , and a high pressure injection unit 14 . When contaminated soil is put into the screen sorting device 10 through the input hopper 11, the screen part 13 filters out particles with a diameter of 2 mm and sprays water at high pressure from the high-pressure spraying part 14 to the screen part 13 ) to remove soil particles and contaminants attached to it. Contaminants attached to the soil particles may also be partially removed by the water sprayed at high pressure from the high-pressure spraying unit 14 .

In the second separation step (S23), the soil having a diameter of 0.2 mm or more, such as sand, is separated and removed from the soil that has undergone the first separation step (S21). Since soil having a diameter of 2 mm or more, such as gravel, has already been separated and removed in the first separation step (S21), in the second separation step (S23), soil with a diameter of less than 2 mm or more, such as sand, is separated and removed.

A high pressure fluidization process may be performed to separate soil with a diameter of 0.2 mm or more. Aggregate dispersion and soil washing are performed to separate nuclides and particulates adsorbed on contaminated soil by applying high-pressure spraying as a high-pressure fluidization process.

8 schematically shows a system in which a high-pressure fluidization process is performed.

Magnet adsorbent 25 is added in the high pressure fluidization process. The magnetic adsorbent 25 may be injected into the process water by an ejection method or an injection method. The radionuclide 24 is combined with the magnetosorbent 25 to form the magnetosorbent 26 to which the radionuclide is adsorbed. The high-pressure pump 23 may perform high-pressure multipurpose injection (PMI) high-pressure injection through the rod 21 . When the PMI high-pressure spraying is performed, the contact time between the magnetic adsorbent 25 and the soil may be increased, and the clay separation and penetration power through the magnetic adsorbent 25 input may be improved. The soil containing the magnetic adsorbent 26 to which the radionuclide is adsorbed is put into the metal gauze 30 provided with the electromagnet 31 around it and can be easily recovered using magnetism.

The magnetic adsorbent 25 is preferably provided as an environmentally friendly material. The environmentally friendly radionuclide removal magnetic adsorbent 25 added to the high-pressure fluidization process without the use of chemicals such as acids or bases can selectively adsorb the radionuclides 24 desorbed from the soil, and thus the radionuclides desorbed from the soil. to prevent re-contamination in the soil. The magnetic adsorbent 25 can be easily separated by magnetic force and reused.

The dispersion efficiency of the high pressure fluidization process can be evaluated as follows.

Dispersion efficiency (%) = (content (%) of less than 100 μm applied to high pressure spraying/content less than 100 μm of raw material (%))*100

The cesium removal efficiency of the high pressure fluidization process can be evaluated as follows.

Removal efficiency (%) = 100 - (Cesium concentration remaining in solution after high-pressure spraying with adsorbent added and sieving of contaminated soil)/(Concentration of cesium remaining in solution after high-pressure spraying and sieving of contaminated soil without adding adsorbent) *100

After the high pressure fluidization process is performed in the second separation step (S23), a sieve separation process may be performed. When the sieving process is performed, the soil with a diameter of less than 0.2 mm and the soil with a diameter of 0.2 mm or more are separated from the soil separated through the high pressure fluidization process.

In the fine soil selection step (S25), the soil having a diameter of 0.1 mm or more is separated from the soil that has undergone the second separation step (S23). Referring to FIG. 9 , hydrocyclone technology may be applied to separate soil with a diameter of 0.1 mm or more in the fine soil selection step (S25). When hydrocyclone technology is applied, soil with a diameter of 0.1 mm or larger is separated by wet.

9 schematically shows a system in which hydrocyclone technology is performed.

The hydrocyclone system 40 includes a cylindrical portion 41 , an inlet 42 , a lower outlet 43 , and an upper outlet 44 . When the contaminant liquid flows into the sidewall of the cylindrical portion 41, contaminants having a large size or density due to a vortex formed therein are collected on the conical wall while turning by centrifugal force and discharged through the lower outlet 43. The dense material is collected in the center and is discharged to the upper outlet 44 by riding the rising vortex.

10 shows a plurality of hydrocyclone systems.

The hydrocyclone system may be provided in plurality. If a plurality of hydrocyclone systems are connected in series, the soil separation efficiency may be higher.

The corresponding particle size distribution ratio of the hydrocyclone process can be evaluated as follows.

Corresponding particle size distribution ratio (%) = Corresponding particle size mass (g)/total mass (g)*100

Solid/liquid separation and waste-liquid treatment processes are performed on the separated solution containing soil with a diameter of 0.1 mm or more. When the solid/liquid separation and waste liquid treatment process is performed, the solution is separated from the solution containing soil with a diameter of 0.1 mm or more, reused in the first separation step or the second separation step, and nuclides in the generated waste liquid can be selectively removed . For solid/liquid separation, a chemical treatment method, chromatography method, centrifugal separation method, etc. may be used. When the solid/liquid separation and waste liquid treatment process are performed, the separated solution may be reused in the first separation step or the second separation step.

In the highly selective separation step (S27), the soil having a large particle size is separated from the fine soil that has undergone the fine soil selection step (S25). When soil with a large particle size is separated, the soil consists of only selected soil with a small particle size. Selected soil is preferably less than 0.04 mm in diameter. Selected soil is preferably disposed of as soil waste. Soils with a diameter of more than 0.04 mm are separated by wet.

11 shows the formation process of the magnetic-soil complex by the advanced screening technology, and FIG. 12 shows the magnetic separation technology of the magnetic-soil complex.

In the advanced sorting and separation step (S27), soil with a diameter of less than 0.04 mm can be selected by magnetic force-based advanced sorting technology. Magnetic force-based advanced screening technology includes selective magnetization technology and magnetic-soil complex magnetic selection technology. Cationic magnetic nanoparticles 53 are selectively attached by utilizing the characteristics of high negative charge and large surface area of small diameter particles 51 such as clay by selective magnetization technology. It is possible to select the soil to which the cationic magnetic nanoparticles are attached by magnetic-soil complex magnetic screening technology. In the case of applying the magnetic force-based advanced sorting technology, it is possible to sort out soil with a diameter of less than 0.04mm with an efficiency of 80% or more of the particle size ratio.

A magnetic separator 60 may be used in magnetic separation technology of the magnetic-soil complex. The magnetic separator 60 may separate the magnetic-soil complex by using gravity and magnetic force. The magnetic separator 60 is magnetic - it is preferable to have sufficient magnetic force so that the soil complex can go up against gravity. The magnetic separator preferably includes an electromagnet so as to selectively apply a magnetic force.

It is desirable that the particle size ratio of less than 0.04 mm after applying the magnetic force-based advanced screening technology is 80% or more, and the particle size ratio can be evaluated as follows.

Particle size ratio (%) = (Particles less than 0.04mm after separation)/(Particles before separation)*100

Solid/liquid separation and waste-liquid treatment processes are performed on the separated solution containing soil with a diameter of 0.04 mm or more. When the solid/liquid separation and waste liquid treatment process is performed, the solution is separated from the solution containing soil with a diameter of 0.04 mm or more, reused in the first separation step and the second separation step, and nuclides in the generated waste liquid can be selectively removed. . For solid/liquid separation, a chemical treatment method, chromatography method, centrifugal separation method, etc. may be used. When the solid/liquid separation and waste liquid treatment process are performed, the separated solution may be reused in the first separation step or the second separation step.

In the purification step (S30), the soil separated in the soil selection step (S20) is treated to generate purified soil and purified waste solution. The purification step (S30) includes a pollution level measurement step (S31), a soil washing step (S33), and a waste liquid treatment step (S35).

In the pollution level measurement step S31 , the pollution level of the soil separated in the soil selection step 20 is measured. In the pollution degree measuring step (S31), the degree of pollution can also be measured for the soil separated in the first separation step (S21), but in general, since the degree of pollution is negligibly low for particles with a diameter of 2 mm or more, in the first separation step (S21) For the separated soil, the degree of contamination of the soil separated from the second separation step (S23), the fine soil selection step (S25), and the high-level separation step (S27) may be measured without measuring the degree of contamination. In the pollution degree measuring step (S31), the soil with a diameter of less than 2 mm and more than 0.2 mm separated from the second separation step (S23), the soil with a diameter of less than 0.2 mm and more than 0.1 mm separated from the fine soil selection step (S25), and a high-level separation step (S27) ), measure the contamination level of soil with a diameter of less than 0.1 mm and 0.04 mm or more separated from it. The pollution level measurement step ( S31 ) may include classifying soil whose pollution level is found to be less than a reference value as purified soil. Soil classified as clarified can be used for other purposes requiring uncontaminated soil.

In the soil washing step (S33), a soil washing process of purifying the soil whose contamination level is determined to be greater than or equal to the reference value in the pollution degree measurement step (S31) is performed. When the soil washing process is performed, the soil is purified using the physical and chemical properties of the contaminants, and this includes methods such as soil washing, incineration, solidification, stabilization, and solvent extraction. It is preferable to use an ex-situ method for soil purification (refer to Korean Patent Publication No. 10-1345398 for the above-ground treatment method). When the soil washing process is completed, the waste liquid is separated. A pollution level measurement step (S31) is performed on the soil from which the waste liquid is separated.

13 is a block diagram schematically illustrating the waste liquid treatment step (S35).

In the waste liquid treatment step (S35), the waste liquid separated in the soil washing step (S33) is treated. The waste liquid treatment step (S35) is a suspended component separation step (S351) of separating an oil component or suspended matter from the waste liquid separated in the soil washing step (S33), a floating component separation step (S351), after the oil component and the suspended matter are separated from the waste liquid After the main nuclide removal step (S353), which removes one or more nuclides selected from the group consisting of cesium (Cs), strontium (Sr) and iodine (I), the residual nuclides in the waste fluid are removed after the main nuclide removal step (S353) After the residual nuclide removing step (S355) and the residual nuclide removing step (S355), it may include a fine particle removing step (S357) of removing the fine particles in the waste liquid.

In the removal of major nuclides (S353) or the removal of residual nuclides (S355), nuclides may be removed through an adsorption process and a precipitation process. In the main nuclides removal step (S353), the nuclides may be treated by a precipitation method, an ion exchange method, an evaporative concentration method, a reverse osmosis method, an ultrafiltration method, or the like. In the major nuclides removal step (S353), cesium (Cs) is adsorbed or ion exchanged by zeolite or metal ferrocyanide, strontium (Sr) is adsorbed or precipitated by zeolite or barium sulfate (BaSO4), and iodine (I) is activated carbon However, it can be removed by adsorption by activated alumina.

When all processes of the method for purifying radioactively contaminated soil according to an embodiment of the present invention are completed, the removal rate of radionuclides in the waste liquid can be evaluated as follows.

Nuclide removal rate (%) = (Nuclide concentration after treatment)/(Nuclide concentration before treatment)*100

If the removal rate of radionuclides in the waste liquid is 95% or more, it is safe as a purified waste liquid, so it can be discharged.

1: Attraction scrubber 2: Motor
3: agitator 4: rotating shaft
5: Inlet 6: Outlet
10: screen sorting device 11: input hopper
12: cover 13: screen part
14: high pressure injection unit
20: underground high-pressure injection equipment 21: rod
22: check valve 23: high pressure pump
24: radionuclide 25: magnetosorbent
26: Magnetosorbent adsorbed with radionuclides
27: reactor
30: metal gauze (iron gause) 31: electromagnet
40: hydrocyclone 41: cylindrical part
42: inlet 43: lower outlet
44: upper outlet 45: sludge
46: sludge pump
51: soil with a diameter of 0.04 mm or more
52: soil less than 0.04 mm in diameter
53: magnetic nanoparticles 54: soil-magnetic nanoparticle complex
60: magnetic separator

Claims (13)

A crushing/washing step of performing a washing process after crushing the soil contaminated with radioactive materials;
a soil screening step of separating soil having a large particle size from the soil by size after the crushing/washing step, selecting selected soil having a small particle size, and treating it as soil waste; and
A purification step of processing the soil separated in the soil selection step to generate purified soil and purified waste solution; including,
The soil selection step
a first separation step of separating and removing soil having a diameter of 2 mm or more from the soil after the crushing and washing step;
a second separation step of separating soil having a diameter of 0.2 mm or more from the soil after the first separation step;
a fine soil separation step of separating soil having a diameter of 0.1 mm or more from the soil after the second separation step; and
After the fine soil separation step, a highly selective separation step of separating soil with a diameter of 0.04 mm or more:
The altitude selection and separation step is
Soil with a diameter of less than 0.04mm is selected by magnetic-based advanced screening technology,
The magnetic force-based advanced screening technology is
selective magnetization technology to form a magnetic-soil complex by selectively attaching cationic magnetic nanoparticles to small-diameter clay particles with high negative charge and large surface area characteristics; and
The magnetic-soil complex to which the cationic magnetic nanoparticles are attached is separated using a magnetic separator - magnetic separation technology of the soil complex; including
A method of purifying radioactively contaminated soil. According to claim 1,
The crushing and washing steps are
A crushing step of crushing the radioactively contaminated soil; and
A washing step of washing the soil after the crushing step; including
A method of purifying radioactively contaminated soil. 3. The method of claim 2,
The washing step
a cleaning agent input step of spraying a cleaning agent on the crushed contaminated soil after the crushing step; and
Agitating step of stirring the crushed contaminated soil; Containing
A method of purifying radioactively contaminated soil. 4. The method of claim 3,
The cleaning agent input step is
It includes a process of evenly dispersing soil agglomerates and cleaning agents by applying ultrasonic energy with an ultrasonic dispersing device.
A method of purifying radioactively contaminated soil. According to claim 1,
The first separation step is
Separating soil with a diameter of 2 mm or more using a screen sorting device
A method of purifying radioactively contaminated soil. According to claim 1,
The second separation step is
A high-pressure fluidization process is performed by introducing a magnetic adsorbent,
After the high-pressure fluidization process is performed, the sieving process is performed.
A method of purifying radioactively contaminated soil. According to claim 1,
The fine soil separation step is
Hydrocyclone technology is applied to wet-separate soil with a diameter of 0.1 mm or more from the soil.
A method of purifying radioactively contaminated soil. 8. The method of claim 7,
The fine soil separation step is
After applying the hydrocyclone technology, the solution is separated from the solution containing the separated soil, and nuclides in the generated waste solution are selectively removed to be reused in the first separation step or the second separation step. and performing a waste liquid treatment process
A method of purifying radioactively contaminated soil. According to claim 1,
The altitude selection and separation step is
After application of the magnetic-soil complex magnetic separation technology, the solution is separated from the solution containing the separated soil, and nuclides in the generated waste solution are selectively removed so that it can be reused in the first separation step or the second separation step. liquid separation and waste liquid treatment process
A method of purifying radioactively contaminated soil. According to claim 1,
The purification step
a pollution level measurement step of measuring the level of pollution of the soil separated in the soil selection step;
a soil washing step of separating the waste solution by purifying the soil whose contamination level is determined to be greater than or equal to the reference value in the contamination level measurement step; and
A waste liquid treatment step of treating the waste liquid separated in the soil washing step; including
A method of purifying radioactively contaminated soil. 11. The method of claim 10,
The contamination level measurement step is
Classifying soil whose contamination level is found to be less than the reference value as purified soil.
A method of purifying radioactively contaminated soil. 11. The method of claim 10,
performing the contamination level measurement step on the soil from which the waste liquid is separated after the soil washing step
A method of purifying radioactively contaminated soil. 11. The method of claim 10,
The waste liquid treatment step
a floating component separation step of separating an oil component or a suspended matter from the waste liquid;
a major nuclide removal step of removing at least one nuclide selected from the group consisting of cesium, strontium, iodine, etc. after the suspended component separation step;
Residual nuclide removal step of removing residual nuclide in the waste solution after the main nuclide removal step; and
Containing;
A method of purifying radioactively contaminated soil.

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