CN107262519B

CN107262519B - Radioactive contaminated soil purification system

Info

Publication number: CN107262519B
Application number: CN201611235823.8A
Authority: CN
Inventors: 赵南赞; 薛曾君; 周玲钟; 姜铉奎
Original assignee: Field Environmental Technology Co ltd; Kepco Nuclear Fuel Co Ltd
Current assignee: Field Environmental Technology Co ltd; Kepco Nuclear Fuel Co Ltd
Priority date: 2016-04-06
Filing date: 2016-12-28
Publication date: 2021-05-25
Anticipated expiration: 2036-12-28
Also published as: CN107262519A; KR101652811B1

Abstract

The present invention relates to a radioactive contaminated soil purification system, and more particularly, to a radioactive contaminated soil purification system which separates gravels and organic substances by a screen and a blower, separates only fine soil having a high degree of radioactive contamination, and improves purification efficiency and a reduction rate that can be reduced to reusable soil.

Description

Radioactive contaminated soil purification system

Technical Field

The present invention relates to a radioactive contaminated soil purification system, and more particularly, to a radioactive contaminated soil purification system that improves purification efficiency by separating fine soil having a high radioactive contamination degree and improves the reduction rate of reducible soil used repeatedly.

Background

In general, the start-up and disintegration of nuclear facilities produces large amounts of radioactive soil.

In particular, when an unexpected accident occurs in the nuclear facility for various reasons such as carelessness of management and natural disaster, the surrounding soil is contaminated by radionuclides released from the nuclear facility.

As described above, soil contaminated with radioactive substances causes direct damage to humans and animals and plants inhabiting on land, and further pollutes ground water flowing in the soil, thereby adversely affecting the overall environment such as the marine environment and the atmospheric environment.

Therefore, in order to reduce the amount of radioactive waste generated or to repair soil contaminated with radioactive nuclides in a short period of time, a soil cleaning technique capable of treating radioactive soil by itself has been recently developed.

As the soil purification technology, there are: a method of immobilizing soil using a polyelectrolyte complex and recovering the immobilized contaminated soil; and a method of measuring the degree of contamination of soil contaminated with a radioactive substance, transferring the contaminated soil to a radioactive waste treatment site, storing the soil for a long period of time, or treating the soil contaminated with the radioactive substance with a purifying agent, based on the measured degree of contamination with the radioactive nuclide, thereby removing the radioactive nuclide from the soil contaminated with the radioactive substance.

In this case, if the contamination degree of the radioactive substance to be measured is extremely low, the method of treating the contaminated soil with the purifying agent to obtain the soil from which the radioactive substance has been removed is carried out as an effective method without storing the contaminated soil in the radioactive waste treatment field for a long time.

However, the conventional soil purification method has the following problems.

First, in the process of purifying soil, there is a problem that a process for separating or purifying organic substances such as leaves mixed in soil is not provided.

Second, a chemical purifying agent is used, and thus equipment configuration costs for treating waste liquid generated during purification are additionally required.

Thirdly, the radioactive substance is mainly adsorbed on fine soil, but the fine soil is not easily separated from the soil, so that the soil cannot be effectively purified, and the soil having a low degree of pollution is also discarded, so that there is a problem in that the reduction rate of the soil which can be reduced to a reusable soil is low.

Documents of the prior art

Patent document 1: korean laid-open publication No. 10-2004-0074514

Disclosure of Invention

Technical problem to be solved

The present invention has been made to solve the above problems, and an object of the present invention is to provide a radioactive contaminated soil purification system which improves the efficiency of soil purification and the reduction rate of soil which can be reduced to reusable soil by separating fine soil and organic matter having radioactive substances adsorbed thereto from soil, and purifies soil only by water washing, thereby minimizing the generation of secondary waste due to waste liquid.

Technical scheme

To achieve the above object, the present invention provides a radioactive contaminated soil purification system, comprising: a pretreatment filter unit including a screen (mesh) for filtering soil in a contaminated area and a blower (blower) for blowing air to organic substances filtered through the screen; the roller screen group is used for spraying high-pressure water to the soil passing through the screen of the pretreatment filtering part to clean the soil and classify the granularity of the soil; the sprayer is used for spraying the soil and the waste liquid which are classified into small-granularity soil and waste liquid through the drum screen group at high pressure so as to remove pollutants on the surface of the soil through physical friction; the hydrocyclone group is used for classifying the granularity of the soil sprayed by the sprayer again; the waste liquid treatment unit aggregates and settles the soil classified as small in particle size by the hydrocyclone group, and dewaters the aggregated precipitate to treat the same as waste.

At this time, it is preferable that the classification standard of the soil particle size classified by the drum screen group is 0.75mm, and the classification standard of the soil particle size classified by the hydrocyclone group is 0.02 mm.

Preferably, the contaminated soil is supplied to the pretreatment filter unit by a conveyor, a measuring device for measuring a radioactive contamination level of the soil transferred by the conveyor is provided at one side of the conveyor, and the conveyor changes a direction so that the soil does not flow into the pretreatment filter unit when the soil contamination level measured by the measuring device is equal to or less than a reference value.

Further, the trommel group is composed of a first sorting part and a second sorting part, the first sorting part includes a first trommel having filtering holes and a first washing part; the second classification part comprises a second rotary screen and a second cleaning part, wherein the second rotary screen is provided with a filtering hole which reclassifies the granularity of the soil passing through the filtering hole of the first classification part to be less than or equal to 0.75 mm; preferably, the organic matter separating tank further includes an organic matter separating tank which receives the soil classified into large-sized (more than 0.75mm) soil by the first classification part and the second classification part and reduces the soil into reusable soil.

Further, preferably, the hydrocyclone group is composed of a first cyclone for accommodating soil and waste liquid flowing in through the ejector and classifying the particle size of the soil into a large particle size and a small particle size; the second cyclone is used for reclassifying the granularity of the soil classified into small granularity by the first cyclone into below 0.02 mm; the soil classified into large particles by the first cyclone is reduced into reusable soil by filtering through a screen, and the soil classified into particles having a particle size of more than 0.02mm by the second cyclone is reduced into reusable soil by measuring the degree of radioactive contamination after passing through a dewatering device or is treated as waste.

The waste liquid treatment section includes a reaction tank including an agitator that accommodates soil and waste liquid classified into small particle sizes by a hydrocyclone group and agitates the soil and waste liquid to activate coagulation sedimentation, and a precipitation tank; the sedimentation tank is used for forming agglutination sediment from the agglutinated sediment flowing from the reaction tank and separating the agglutinated sediment into sludge and water; preferably, the sludge subjected to the coagulation treatment in the sedimentation tank is treated as waste by a dewatering device, and the separated water is reused as a cleaning liquid or is discharged to the environment after being filtered.

Advantageous effects

The radioactive contaminated soil purification system of the present invention has the following effects.

First, before cleaning the soil, the gravel and organic matter are separated for the first time by a screen and a blower, so that the efficiency of the purification operation can be improved.

That is, since radioactive contaminants are not adsorbed on objects having a large particle size such as gravel mixed in soil, and thus it is not necessary to perform a washing operation to reduce the operation efficiency, the objects are separated by a screen, and when organic matter such as leaves is washed together with soil, the efficiency is reduced in the process of classifying the particle size of the soil, and thus the objects can be separated by a blower that injects air, thereby improving the efficiency of the purification operation.

Second, the contaminated materials on the soil surface are removed by physical friction of an injector (ejector) injecting soil and water at a high pressure, so that the efficiency of the soil purification operation can be improved.

In particular, only fine soil having a high degree of radioactive contamination is separated again by the hydrocyclone from the soil purified by the ejector, so that the amount of the remaining soil reduced to the soil for reuse can be maximized.

Thirdly, in the process of first supplying the soil to be purified, whether radioactive contamination exists in the soil is determined in advance by a measuring device provided on the conveyor, thereby having an effect of preventing inefficacy of blindly cleaning uncontaminated soil.

Fourth, in the washing and size classification of contaminated soil, washing and size classification of soil is accomplished using only water, so that generation of waste liquid can be minimized.

Drawings

Fig. 1 is a view showing a radioactive contaminated soil purification system according to a preferred embodiment of the present invention.

Reference numerals

100: the conveyor 110: measuring instrument

200: the pretreatment filter unit 210: screen mesh

220: blower 300: drum screen group

310: first classification section 311: a first cleaning part

312: first trommel 320: second classification part

321: second cleaning unit 322: second drum sieve

350: organic matter separating tank 360: waste liquid collecting tank

400: the ejector 500: hydraulic cyclone set

510: first swirler 511: first cyclone storage tank

520: second swirler 530: equalizing tank

540: storage tank 600: waste liquid treatment section

610: the reaction tank 611: stirrer

620: the settling tank 630: treatment water tank

400: ejector

Detailed Description

The terms or words used in the present specification and claims should not be construed restrictively as conventional meanings or dictionary meanings, but should be construed as meanings and concepts conforming to the technical idea of the present invention on the basis of the principle that the inventor can properly define the concept of the terms in order to describe his invention in the best way.

Referring to fig. 1, a radioactive contaminated soil purification system according to a preferred embodiment of the present invention will be described.

The radioactive contaminated soil purification system is technically characterized in that the particle size of soil is more finely classified by physical classification based on a screen and a blower, classification based on the specific gravity of water, and classification based on a hydrocyclone.

That is, the smaller the particle size of the soil, the higher the adsorption rate of radioactive contaminants, but since fine soil having a small particle size is classified by the above-described washing and classification of particle size several times, the reduction rate of the soil can be increased and the efficiency of the purification operation can be maximized.

Therefore, the radioactive contaminated soil purification system includes a conveyor 100, a pretreatment filter unit 200, a trommel group 300, an ejector 400, a hydrocyclone group 500, and a waste liquid treatment unit 600.

The conveyor 100 automatically transfers soil to be cleaned, that is, soil supplied from a region where radioactive contamination is predicted to occur, to the pretreatment filter unit 200.

The soil is preferably supplied in ton bags and the supplied soil falls through a hopper H onto the conveyor 100.

The conveyor 100 corresponds to the pretreatment filter unit 200, and thus soil transferred by the conveyor 100 is automatically supplied to the pretreatment filter unit 200.

Here, a measuring device 110 for measuring the radioactive contamination degree may be further provided above the conveyor 100.

The measuring device 110 measures the radioactive contamination degree of the soil transferred by the conveyor 100, and when the soil measured by the measuring device 110 on the conveyor 100 is a soil with a low radioactive contamination degree (a reusable soil), the transfer direction of the conveyor 100 is switched so that the soil does not flow into the pretreatment filter unit 200.

The purpose is to improve the efficiency of the decontamination operation by filtering the uncontaminated soil in advance before washing because the soil to be decontaminated has a wide range and there is a possibility that a large amount of uncontaminated soil may exist.

Although not shown, the conveyor 100 is configured to be reversible, so that the uncontaminated soil is transferred to a different location without flowing into the pretreatment filter unit 200 and immediately returned to a normal environment.

Next, the pretreatment filter unit 200 serves to filter soil or organic matter having a large particle size for the first time from among the soil supplied by the conveyor 100.

That is, since the soil is composed of a plurality of particle sizes and the supplied soil may contain a large amount of organic substances such as leaves, roots, branches, etc. in addition to gravel and stones, the soil and the organic substances are physically classified by the pretreatment filter unit 200.

The pretreatment filter unit 200 is composed of a mesh 210 and a blower 220.

The mesh 210 is configured to filter organic substances such as gravel having a large particle size and leaves, and therefore the size of the filtering holes of the mesh 210 is preferably 30 mm.

Accordingly, the gravel and organic matter contained in the soil supplied from the conveyor 100 are filtered by the mesh 210 for the first time.

The blower 220 is configured to blow the organic matter filtered by the screen 210 to a separate treatment site, and is therefore configured to be capable of ejecting air.

That is, the organic matter on the screen 210 is moved to another place by the blower 220, so that the gravel having a large particle size and the organic matter can be reclassified.

Next, the trommel group 300 plays a role of cleaning the soil filtered by the pretreatment filter unit 200, that is, the soil dropped through the mesh 210, and classifying the particle size of the soil.

That is, the soil dropped through the pretreatment filter unit 200 is transferred to a drum screen (dry screen) by water pressure, and the soil is washed and classified into particles by stirring by the rotation of the screen and high-pressure spraying of a washing liquid in the drum.

Here, it is preferable that the drum screen set 300 is composed of the first classification part 310 and the second classification part 320 so that the grain size classification of the soil can be finely completed.

The first sorting unit 310 includes a first cleaning unit 311 and a first trommel 312, and the first cleaning unit 311 is configured to clean soil filtered to a particle size of 30mm or less by the pretreatment filter unit 200 by spraying water at a high pressure; the first trommel 312 is a device for reclassifying the soil by rotating.

Here, the size of the filtering holes of the first trommel 312 is preferably 3 mm.

That is, the soil is classified into a grain size of 3mm or less by the first classification section 310 and transferred to the second classification section 320.

The second classification section 320 is composed of a second washing section 321 and a second washing section 321, and the second washing section 321 is configured to wash the soil having a grain size of 3mm or less filtered by the first classification section 310 by spraying water at a high pressure; the second drum screen 322 is rotated to classify the size of the soil again.

Here, the size of the filtering hole of the second trommel 322 is preferably 0.75 mm.

It is preferable that the washing waste liquid generated during the washing and the size classification of the soil by the drum screen group 300 is repeatedly transferred to the first and

second classifiers

310 and 320 by a pump, so that the washing waste liquid can be repeatedly used during the washing of the soil.

In addition, the soil classified into the size of more than 3mm by the drum screen group 300 is transferred to the organic matter separating tank 350.

The organic matter separating tank 350 serves to receive soil having a low radioactive contamination degree, i.e., soil having a particle size of more than 3mm filtered through the drum screen group 300, and then to wash the soil again and reuse it as original soil.

In detail, the organic matter separating tank 350 filters the organic matter floating on the upper portion of the water tank by the supply of the cleaning solution with a screen, and the soil having a particle size of more than 3mm is separated from the cleaning solution by another screen after settling, thereby being used as the soil for reuse.

In addition, soil classified into a grain size of 0.75mm or less by the trommel group 300 is accommodated in a waste liquid collecting tank 360 which is additionally provided.

The waste liquid collection tank 360 is provided with an ejector 400, and the soil waste liquid collected in the waste liquid collection tank 360 can be sent under pressure to a hydrocyclone unit 500, which will be described later, through the ejector 400.

The ejector 400 is configured to eject soil and waste liquid settled in the waste liquid collecting tank 360 at a high pressure, thereby removing contaminants on the soil surface by physical friction.

Second, the hydrocyclone group 500 functions to more finely classify the particle size of the soil classified by the trommel group 300 by means of a hydrocyclone.

That is, the soil is physically classified in terms of particle size by the screen 210, the blower 220, and the drum screen group 300, and then the fine soil having a high degree of radioactive contamination is classified by the hydrocyclone method.

Generally, according to the research papers published so far, the size of the fine soil having a high radioactive contamination adsorption rate is 0.02mm or less, but when only the screen 210 and the drum screen group 300 are used, the classification of the soil particle size is limited to 0.75mm, and the fine soil having a high radioactive contamination degree can be classified by the hydrocyclone group 500.

The hydrocyclone battery 500 is preferably constructed with a first cyclone 510 and a second cyclone 520 to improve the efficiency of particle size classification of the soil.

The first cyclone 510 is to reclassify the soil and the waste liquid injected through the injector 400 of the waste liquid collecting tank 360 by means of a hydrocyclone.

The classified soil had a particle size of 0.075 mm.

That is, soil having a particle size of 0.075mm or less is transferred to the additional first cyclone storage tank 511 through the first cyclone 510, and soil having a particle size of more than 0.075mm is separated from the washing liquid through the additional screen and then reduced to reuse soil.

Preferably, the cleaning effluent generated during the process is diverted to effluent collection tank 360 for reuse.

The second cyclone 520 performs a function of reclassifying soil classified to 0.075mm or less by the first cyclone 510, and receives soil and waste liquid supplied from the first cyclone storage tank 511.

The second cyclone 520 is used to reclassify soil having a particle size of 0.075mm or less by means of a hydrocyclone, wherein the classified soil has a particle size of 0.02 mm.

That is, the soil having a particle size of 0.02mm or less classified by the second cyclone 520 may be classified into fine soil most contaminated with radioactive substances and discarded, and the soil having a particle size of more than 0.02mm may be discarded or reduced to soil for reuse according to the measured radioactive contamination degree.

To perform this process, the soil classified into a grain size of 0.02mm or less in the second cyclone 520 is transferred to the equalization tank 530, and the soil classified into a grain size exceeding 0.02mm is transferred to the storage tank 540.

The soil transferred to the storage tank 540 is dehydrated by the dehydration device F to be produced into a soil block, and when the radioactive contamination degree of the soil block is equal to or higher than a reference value, the soil block is discarded, and when the radioactive contamination degree of the soil block is lower than the reference value, the soil block is returned to be reused.

Here, the dewatering device F is preferably a filter press (filter press), and water purified during dewatering is transferred to the organic matter treatment tank 350 and reused.

The soil having a particle size of 0.02mm or less transferred to the equilibrium tank 530 is transferred to a waste liquid treatment unit 600 described later as a waste treatment target.

Next, the waste liquid treatment unit 600 performs a waste treatment of soil having a particle size of 0.02mm or less, and receives and treats the waste liquid and soil contained therein supplied from the equalization tank 530.

The waste liquid treatment unit 600 filters fine soil contained in the waste liquid by coagulation and sedimentation, and treats the waste liquid as lump waste, and includes a reaction tank 610, a sedimentation tank 620, and a treatment water tank 630.

The reaction tank 610 receives fine soil having a particle size of 0.02mm or less transferred from the equilibrium tank 530, and performs a process for aggregating and precipitating the fine soil, and a coagulation sedimentation agent is charged into the reaction tank 610.

That is, when the reaction tank 610 is filled with the waste liquid containing the reference amount of fine soil, the coagulation sedimentation agent is charged, and the stirring operation is performed in the reaction tank 610 to increase the reaction between the fine soil in the waste liquid and the coagulation sedimentation agent.

For this, it is preferable that a stirrer 611 is provided in the reaction tank 610.

The settling tank 620 is configured to activate the coagulation-sedimentation reaction of the waste liquid mixed with the coagulation-sedimentation agent.

That is, the waste liquid in the reaction tank 610 is mixed with the coagulation-sedimentation agent by the stirrer 611, and then is retained for a certain period of time, and then is transferred to the sedimentation tank 620 to activate the coagulation-sedimentation reaction.

Then, the precipitate after the coagulation and sedimentation is subjected to a dehydration process by the filter press F, and the dehydrated waste is transferred to another waste treatment site and treated.

In addition, the processing water tank 630 contains water subjected to the purification processing in the settling tank 620 and the filter press F, and the purified water collected in the processing water tank 630 may be reused as a cleaning liquid for the purification system or discharged to the general environment after passing through a filter.

Thereby completing the purification process of the contaminated soil.

As described above, the radioactive contaminated soil purification system of the present invention is technically characterized in that the contaminated soil is classified into fine soils in terms of particle size and is washed with only water, thereby minimizing the generation of waste liquid.

In particular, the efficiency of the purification operation can be improved by separating the soil and the organic matter using a screen and a blower, and only fine soil having a high degree of radioactive contamination can be separated by the hydrocyclone system, so that the amount of soil to be reduced to the general environment can be increased.

That is, only fine soil having a high actual radioactive contamination degree can be separated through a series of processes, and therefore, it is possible to minimize the case where soil having a low radioactive contamination degree is treated as waste.

The specific examples described in the present invention have been described in detail, but it is obvious to those skilled in the art that various changes and modifications can be made within the technical spirit of the present invention, and such changes and modifications also fall within the scope of the claims.

Claims

1. A radioactive contaminated soil decontamination system, comprising:

a pretreatment filter unit including a screen for filtering soil in a contaminated area and a blower for blowing air to the organic matter filtered by the screen;

a drum screen group for cleaning the soil by spraying high-pressure water to the soil passing through the screen of the pretreatment filter unit and classifying the particle size of the soil;

an ejector that ejects the soil and the waste liquid classified into small-sized soil and waste liquid through the drum screen group at a high pressure to remove contaminants on the soil surface by physical friction;

a hydrocyclone group which reclassifies the particle size of the soil sprayed through the sprayer;

a waste liquid treatment unit for aggregating and settling the soil classified as small in particle size by the hydrocyclone group and dewatering the aggregated precipitate to treat the same as waste,

the roller screen group consists of a first classification part and a second classification part, and the first classification part comprises a first roller screen with filtering holes and a first cleaning part; the second classification part comprises a second drum screen and a second cleaning part, wherein the second drum screen is provided with a filtering hole for reclassifying the soil with the granularity of less than 0.75mm passing through the filtering hole of the first classification part, namely the classification standard of the soil granularity classified by the drum screen group is 0.75 mm;

further comprises an organic matter separating tank which receives soil classified as large in grain size, i.e., soil having a grain size exceeding 0.75mm, by the first classification section and the second classification section, and reduces it to reusable soil,

the hydrocyclone group is composed of a first hydrocyclone and a second hydrocyclone, the first hydrocyclone is used for accommodating soil and waste liquid flowing in through the ejector and classifying the particle size of the soil into large particle size and small particle size; the second cyclone is used for reclassifying the granularity of the soil classified into small granularity by the first cyclone to be less than 0.02mm, namely the classification standard of the granularity of the soil classified by the hydrocyclone group is 0.02 mm;

the soil classified into large particles by the first cyclone is filtered by a screen and reduced into reusable soil, the soil classified into particles having a particle size of more than 0.02mm by the second cyclone is subjected to a dehydration apparatus and then reduced into reusable soil or disposed of as waste by measuring a radioactive contamination degree, and the soil classified into particles having a particle size of 0.02mm or less is classified into fine soil most contaminated with radioactive substances and disposed of.

2. The radioactive contaminated soil decontamination system of claim 1,

contaminated soil is supplied to the pre-treatment filtering part by a conveyor,

a measuring device for measuring the radioactive contamination degree of the soil transferred along with the conveyor is arranged at one side of the conveyor,

when the soil pollution degree measured by the measuring device is below a reference value, the direction of the conveyor is changed so that the soil does not flow into the pretreatment filtering part.

3. The radioactive contaminated soil purification system according to claim 1, wherein said waste liquid treatment section includes:

a reaction tank including an agitator that accommodates soil and waste liquid classified into small particle sizes by a hydrocyclone group and agitates the soil and the waste liquid to activate coagulation sedimentation;

a sedimentation tank for separating the flocculated sludge flowing from the reaction tank into sludge and water by forming flocculated sludge and sedimentation;

the sludge subjected to the coagulation treatment in the sedimentation tank is treated as waste by a dewatering device, and the separated water is reused as a cleaning liquid or is discharged to the environment after being filtered.