KR101693575B1 - Apparatus for washing soils contaminated by heavy metals and method therefor - Google Patents

Abstract

The present invention relates to an apparatus for treating heavy metal-contaminated soil and a treatment method. According to an embodiment of the present invention, a system for treating heavy metal-contaminated soil comprises: a particle sorting part separating rubble stones bigger than the minimum rubble stone particle size and pebbles bigger than the minimum pebble particle size after the heavy metal-contaminated soil is supplied, and then releasing the soil after separating fine soil having the particle size smaller than the minimum purification particle size as well as contaminated soil having the particle size satisfying a value between the minimum purification particle size and the minimum pebble particle size; a water treatment part releasing fine soil sorted from the particle sorting part after purifying the same; and a soil purification part separating the contaminated soil sorted from the particle sorting part, and then eluting magnetic contaminated soil, while nonmagnetic contaminated soil is pulverized to float the same, and then is separated from moisture.

Description

FIELD OF THE INVENTION [0001] The present invention relates to an apparatus for treating soil contaminated with heavy metals,

The present invention relates to a contaminated soil treatment apparatus and a treatment method thereof, and more particularly, to a contaminated soil treatment apparatus for sorting soil contaminated with heavy metals by particle size and purifying the soil by minimizing the chemical treatment object through magnetic force selection, And a method of processing the same.

Due to urban expansion and industrial development, domestic sewage and factory wastewater are increasing, and various domestic wastewater and factory wastewater are flowing into the rivers. Domestic sewage and factory waste water are flowing into the river. As well as domestic wastewater and industrial wastewater, large amounts of water are introduced into the river, and foreign matter remaining on the surface of the river flows into the river to form sediments in the river.

Sediments formed in the rivers not only impede the smooth flow of water but also generate odor from water congestion and increase flood damage in the flood. The sediments contaminated with organic matter or heavy metals, Causing environmental and ecological problems in the long run.

In order to smoothly flow the water in the river, dredged sediments are periodically dredged. In dredged soil, not only domestic sewage and factory wastewater, but also heavy pollutants with high concentration of heavy metals are contained .

Especially, in the downstream area of the river where the harbors are installed and in the coastal waters, the pollutants tend to accumulate due to the stagnation of the flow rate, and the high content of silt and clay in the fine particles generally shows high heavy metal content. In addition, sediments accumulating heavy metal concentrations may be generated in the middle upstream of the river when the industrial complex is adjacent to the river. In other words, sediments from rivers, lakes and marine ports can be a source of pollutants discharged to the aquatic system and at the same time, a source of pollutants that are continuously discharged to the aquatic environment. Long-lived sediments can negatively impact water management, such as impeding the ability of rivers to flow during floods or lowering lake reservoirs. Particulate matter (sediment), which is desorbed from the surface and introduced into the water body, is adsorbed by nutrients, heavy metals, and organic substances and flows into rivers and lakes and flows or stagnates to form sediments. The pollutants present in the sediments are eluted into the logarithm of the sediments according to the conditions such as hydrogen ion concentration, dissolved oxygen, redox potential, organic carbon content, and then repeatedly flow into the benthic organisms or combine with the sediments again. Bounded contaminants between sediments can be resuspended by disturbances such as bioturbation, floods, and dredging by the activities of benthic organisms, affecting water quality and aquatic ecosystems.

The dredging of sediment has a great influence on the water environment as well as the ability of the river to pass through and the storage capacity of the reservoir. However, in Korea, the systematic and technological basis for judging and managing polluted sediments, treating dredged pollutants and recycling them is insufficient.

Since the efficiency and economical efficiency of such dredged soil are poor, it is required to sort out and purify the dredged soil contaminated with heavy metal pollutants and recycle them.

It should be understood that the foregoing description of the background art is merely for the purpose of promoting an understanding of the background of the present invention and is not to be construed as adhering to the prior art already known to those skilled in the art.

SUMMARY OF THE INVENTION The present invention has been made in order to solve the above problems, and it is an object of the present invention to maximize recycling by sorting and sorting soil contaminated with heavy metals by a certain standard, Which is capable of minimizing the purification treatment cost and improving the purification efficiency, and a method of treating the heavy metal contaminated soil.

In order to accomplish the above object, the heavy metal contaminated soil treatment system according to an embodiment of the present invention is a system for treating a heavy metal polluted soil, which comprises supplying ground contaminated with heavy metals, separating gravels having a minimum particle size and / And a purifier for purifying and discharging the fine soil selected by the particle size selector, and a purifier for purifying the polluted soil selected from the particle size selector by a magnetic force And separating the magnetic contaminated soil to remove the non-magnetic contaminated soil, and separating the non-magnetic contaminated soil from the soil.

Wherein the particle size selector comprises a feed hopper for supplying soil contaminated with heavy metals, a sorting unit for separating gravel or gravel having a minimum size of gravel by treating the soil supplied through the feed hopper, and treating the soil passing through the sorting unit for purification And may include a cyclone device that separates fine soil below a minimum particle size.

Wherein the sorting unit comprises a first separator for treating the soil supplied through the feed hopper to separate lumps of a minimum particle size of the rubble and a second separator for separating the gravels having a minimum particle size of the gravel by processing the soil having passed through the first separator . ≪ / RTI >

The cyclone device may comprise at least one hydrocyclone.

The particle size selector may further include a third separator for separating the fine soil contained in the contaminated soil that has passed through the cyclone apparatus and having a pore size smaller than the minimum pore size.

The soil remover includes a magnetic separator for separating the contaminated soil that has passed through the particle size discriminating unit into a magnetic contaminated soil having magnetism and a non-magnetic contaminated soil having non-magnetic property by adding magnetic force, a crusher for physically crushing non- A pressurized flotation tank for flushing the non-magnetic contaminated soil crushed through the crusher by floating the contaminants through the fine bubbles, a leaching treatment device for separating the heavy metals by reacting the magnetic contaminated soil with the leaching agent, And a sand unit for separating the contained water of the purified soil purified through the treatment device.

The elution processing apparatus may include a drying tank for mixing the magnetic contaminated soil with an eluting agent to elute a chemically bound heavy metal and a storage tank for storing the purified soil purified in the drying tank and discharging the purified soil to the sand unit .

The elution treatment apparatus may further comprise a pH adjustment tank for adjusting the pH of the purified soil purified in the above-mentioned leaching tank.

The crusher is provided with a blade for rotating the non-magnetic contaminated soil to be charged, a motor for driving the blade to rotate, and a tip for separating contaminants from the non- . ≪ / RTI >

The pressurized floatation vessel may include an ultrasonic generator capable of generating ultrasonic waves at a lower portion thereof and transmitting the generated ultrasonic waves.

And a skimmer installed at an upper portion of the pressurized floating tank to remove floating contaminants.

The water treatment unit includes a sedimentation tank in which the fine soil flows into the sedimentation tank, which is flocculated, precipitated and discharged by the polymer flocculant, a concentrated tank in which the fine soil discharged from the sedimentation tank flows in and is concentrated, And a filter press to remove the filter press.

Also, the method of treating heavy metals contaminated soil according to one embodiment of the present invention is a method of treating heavy metals contaminated soil according to an embodiment of the present invention, in which the soil contaminated with heavy metals is supplied to separate gravels and gravels having a minimum particle size greater than or equal to the minimum particle size, A process for sorting the polluted soil between the particle size and the minimum particle size of the gravel, a water treatment process for purifying and discharging the selected fine soil in the particle size selection process, and a process for separating the polluted soil selected through the particle size selection process , A soil purification process in which the separated magnetic contaminated soil is eluted, the non-magnetic contaminated soil is crushed and floated, and the eluted or floated soil is separated from moisture and recovered.

The particle sorting process includes a first sorting process of receiving soil contaminated with heavy metals and separating lumps having a minimum particle size of the rubble, a second sorting process of separating the gravels having a minimum particle size of the gravel by treating the soil subjected to the first sorting process And a cyclone sorting step of separating the soil subjected to the second sorting process through the cyclone apparatus to remove the fine soil having a size smaller than the minimum particle size of the purification.

The particle size selection process may further include a third sorting step of separating the fine soil having the purest minimum particle size included in the contaminated soil subjected to the cyclone sorting process.

The soil remediation process includes a magnetic force selection process of separating the polluted soil selected in the particle size selection process into magnetic polluted soil and non-magnetic polluted soil through magnetic force, magnetic separation of the magnetic polluted soil separated by the magnetic separation process, An elution process of eluting the soil heavy metals, a pulverizing process of physically crushing the non-magnetic contaminated soil, a pressurized floating process of floating the non-magnetic contaminated soil through the micro-bubbles through the pulverization process, And a water removing step of removing moisture of the purified soil that has undergone the pressurized floatation process.

The soil remediation process may further include a pH control process of neutralizing the purified soil after the elution process by adding a pH adjusting agent thereto.

In the water treatment process, the polymer flocculant may be added to the fine soil, followed by flocculation and precipitation, followed by concentration and then removing water.

The average particle size of the rubble is 50 mm or more, the average particle size of the gravel is 5 to 50 mm, the average particle size of the contaminated soil is 0.075 to 5 mm, and the average particle size of the fine soil is less than 0.075 mm.

The eluent may comprise sulfuric acid, hydrochloric acid or phosphoric acid.

The pH adjusting agent may be sodium hydroxide.

The bubbles in the pressurized flotation process may be 0.1 to 10 mu m microfine.

And may be to add vibration by ultrasonic waves in the pressurized floating process.

According to the heavy metal contaminated soil treatment system and treatment method of the present invention, the following effects can be obtained.

First, the heavy metal contaminated soil which can not be recycled due to the heavy metal contamination, and especially the contaminated dredged soil is purified and recycled, thereby maximizing the aggregate recycling and minimizing the final landfill amount, thereby reducing the contamination by landfill.

Second, the present invention can purify effectively by selecting an object to purify the soil contaminated with heavy metals by particle size separation.

Third, soil contaminated with heavy metals are separated by high and low concentrations using the property that the soil is more than a certain magnetism. Soil contaminated with high concentration is purified through elution process, and soil contaminated with low concentration is subjected to physical grinding and wounding It is possible to purify contaminated soil effectively with heavy metals at low cost through the process.

1 is a simplified view of a heavy metal contaminated soil treatment system according to an embodiment of the present invention.
2 is a view showing a crusher in a heavy metal contaminated soil treatment system according to an embodiment of the present invention.
3 is a view showing a pressurized float in a heavy metal contaminated soil treatment system according to an embodiment of the present invention.
4 is a process diagram of a method for treating heavy metal contaminated soil according to an embodiment of the present invention.
FIG. 5 is a view illustrating a result of heavy metal contamination measurement according to a method of treating heavy metal contaminated soil according to an embodiment of the present invention.

The terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the invention. The singular forms as used herein include plural forms as long as the phrases do not expressly express the opposite meaning thereto. Means that a particular feature, region, integer, step, operation, element and / or component is specified, and that other specific features, regions, integers, steps, operations, elements, components, and / And the like.

Unless otherwise defined, all terms including technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. Commonly used predefined terms are further interpreted as having a meaning consistent with the relevant technical literature and the present disclosure, and are not to be construed as ideal or very formal meanings unless defined otherwise.

Hereinafter, a heavy metal contaminated soil treatment system according to a preferred embodiment of the present invention will be described with reference to the accompanying drawings.

The heavy metal contaminated soil treatment system according to the present invention is intended to purify and treat soil contaminated with heavy metals such as copper, zinc and cadmium. For example, it treats heavy metals contained in dredged soil and recycles them.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a view showing an overall configuration of a heavy metal contaminated soil treatment system according to an embodiment of the present invention; FIG. As shown in FIG. 1, the heavy metal contaminated soil treatment system according to an embodiment of the present invention mainly includes a particle size sorting unit 100, a water treatment unit 200, and a soil remover 300.

The particle size selection unit 100 receives soil contaminated with heavy metals to separate gravels and gravels having a minimum particle size greater than or equal to the minimum particle size of the gravel and fine gravels having a particle size smaller than the minimum particle size of purification, . The particle sorting unit 100 may include a feed hopper 110, a sorting unit 120, and a cyclone apparatus 130.

The feed hopper 110 is a device for inputting soil contaminated with heavy metals and may be formed in the form of a rectangular funnel. The sorting unit 120 is for picking up rubble and gravel that can be used as aggregate immediately without basically purifying the contaminated soil that is fed through the feed hopper 110. The sorting unit 120 may include a first sorting unit 121 and a second sorting unit 122.

The first sorting device 121 is installed below the feed hopper 110. However, in the present invention, it is possible to remove lumps having an average particle size of about 50 mm or more by vibrating the screen. It is possible to recycle the lumps of an average particle size of about 50 mm or more because the contamination by heavy metals is low. A belt conveyor 123 may be installed on the lower portion of the first sorting device 121 so that the contaminated soil from which the rubble is removed can be moved. Various conveying means as well as a belt conveyor may be used, and the present invention is not limited thereto.

A second separator 122 may be installed at the end of the belt conveyor 123. The second sorting device 122 is a device for separating the gravels having an average particle size of 5 mm or more from the contaminated soil having passed through the first separator 121 and having an average diameter of less than 50 mm. Any device that can be separated by particle size can be used. In this embodiment, a screen may be provided and a plurality of springs may be connected to a lower portion of the main body so as to be connected to the upper portion of the support body so as to be elastically flowable with respect to the tear body. In order to vibrate the main body of the second selector 122, a motor is installed on the support body, and the rotation axis of the motor is connected to the lower portion of the main body so as to elastically flow. In the present invention, gravels having a diameter of 5 mm or less are discharged, and contaminated soil of less than 5 mm is transported to the lower part. The lower part of the upper screen has a space for storing less than 5 mm of soil and sprayed water when sorted. In the storage space, there is a pump for circulating water and soil in the form of slurry so that soil is not settled, and a pump for cyclone apparatus 130 as a next step.

The cyclone device 130 may be connected to separate the fine soil smaller than the usable size of the aggregate from the contaminated soil that has passed through the second separator 122. The cyclone device 130 may be a wet cyclone device capable of separating the particles by the centrifugal force and the gravity force, and may be implemented in various forms. In the present embodiment, however, the cyclone device includes the first cyclone 131, And may include a second cyclone 132. The first cyclone 131 is a hydrocyclone for sorting the fine soil having an average diameter of less than 0.075 mm from the contaminated soil supplied through the second separator 122. The first cyclone 131 has a purifying minimum particle size . The purifying minimum particle size is a minimum particle size that can be purified through the soil purifying unit 300, and may be about 0.075 mm in the present invention. It is possible to adjust the classifying point by changing operating conditions. The second cyclone 132 is a hydrocyclone apparatus for separating additional fine soil from the contaminated soil treated in the first cyclone 131. The second cyclone 132 is used for sorting fine soil having an average diameter of less than 0.075 mm Hydrocyclone.

In the present invention, the first cyclone 121 may be composed of a multistage cyclone (for example, two stages in series), and the second cyclone 132 may be composed of multiple cyclones (for example, four stages in parallel). In order to maximize the screening efficiency, a multi-cyclone is applied after minimizing the size of the hydron cyclone.

The contaminated soil discharged through the cyclone apparatus 130 has an average diameter of 0.075 to 5 mm and can be directly supplied to the soil remover 300 and processed. However, in order to improve the screening efficiency, (140) may be connected. The screen of the third separator 140 is the same as that of the second separator 122. The screens used in the third separator 140 are for separating the fine particles having an average particle size of less than 0.075 mm, The soil is transferred to the water treatment unit 200 and the contaminated soil having an average diameter of 0.075 to 5 mm to be filtered is conveyed to the soil purification unit 300.

The water treatment unit 200 is connected to the particle size selection unit 100 so as to purify the selected fine soil. The water treatment unit 200 may include a water collecting tank 210, a settling tank 220, a concentration tank 230, a filtration tank 240, a flow rate adjusting tank 250, and a filter press 260. The fine soil separated through the particle size selecting unit 100 enters muddy water mixed with water and moves to the settling tank 220. The polymer flocculant reservoir 221 may be connected to the settling tank 220 to supply the polymer flocculant to the settling tank 220 and may be supplied to the settling tank 220 by a pump. In the sedimentation tank 220, the polymer flocculant is agglomerated in the colloidal form so that the sediment is submerged by gravity. At this time, the concentration tank 230 is installed so as to concentrate the soil that has settled downward. The water collecting tank 210 may be connected to the sedimentation tank 220. The fine soil concentrated in the concentration tank 230 is dehydrated in the filter press 260 using the AOD pump, the cake is waste treated, and the filtrate is transferred to the water collection tank 210 through the filtrate storage tank 270. The water separated in the thickener tank 230 is transferred to the flow rate regulator 250 through the filtration tank 240 and can be used as the process water of the particle size sorter 100 again.

On the other hand, the soil purging unit 300 separates and separates the polluted soil selected through the particle size selecting unit 100 through the magnetic force, purifies the purged soil, and finally removes moisture to separate the purged soil. The soil remover 300 may include a magnetic separator 310, a crusher 320, a pressurized floating tank 330, an elution processor 340, and a sand unit 350.

The magnetic separator (310) separates the contaminated soil selected by the particle size selector into magnetic contaminated soil and non-magnetic contaminated soil by magnetic force. The heavy metals contained in the soil have a certain degree of magnetic activity due to the existence of oxide minerals such as hematite and magnetite. In particular, soil contaminated with cadmium, chromium, copper, nickel, and zinc, which are separated by pollutants in the Soil Environment Conservation Act, has relatively high autonomy. Therefore, since the magnetic susceptibility varies depending on the degree of contamination of heavy metals, it is possible to separate them through the magnetic separator 310.

Here, the magnetic contaminated soil is separated through the magnetic separator 310 and the magnetism is strong. The soil is a soil with a high degree of heavy metal contamination, and the non-magnetic soil is a soil having a low magnetic property due to a low heavy metal contamination degree. In the present invention, a permanent magnet of about 3000 gauss was used.

The crushing tank 320 physically crushes the non-magnetic contaminated soil selected by the magnetic separator 310. Non-magnetic contaminated soils with a relatively weak combination of soil and heavy metals are applied. Various forms can be adopted for the physical pulverization. 2 is a cross-sectional view schematically illustrating a crusher according to an embodiment of the present invention. 2, in this embodiment, the crushing tank 320 includes a motor 321 for rotating driving, a blade 322 for rotating the soil, and a tip 323 at an upper tip to be hit through the blade can do. The non-magnetic contaminated soil strikes the upper tip 323 through the rotation of the blade 322, thereby physically impacting and separating the contaminants.

The pressurized floating tank 330 is a device for removing contaminants from the non-magnetic contaminant soil in which the contaminants are physically separated from the crush tank 320. When the air is dissolved in the waste water to be treated under pressure, the air that is dissolved in the waste water rises as air bubbles, and is attached to the periphery of the suspended material to float the suspended matter onto the water. At this time, the bubble used may be a microfine film having a thickness of 0.1 to 10 mu m. The minute bubbles have a slower rising speed in water than ordinary bubbles having a size of several tens of micrometers, and can increase the residence time of the bubbles, increase the specific surface area, and increase the adsorption force at the gas-liquid interface. In addition, the OH - (hydroxide ion) is collected at the interface and the surface is charged with (-), so that the adhesion of the heavy metal to the cation can be increased. 3 is a view showing a pressurized floating tank in a heavy metal contaminated soil treatment system according to an embodiment of the present invention. A bubble generator 332 capable of generating minute bubbles and an ultrasonic generator 331 for transmitting vibration generated by ultrasonic waves to the pressurized floating vessel may be disposed under the pressurized floating vessel 330. [ When ultrasonic vibration is generated in the pressurized floating tank, shock waves are generated by the ultrasonic waves, so that the contaminants can be effectively lifted and removed together with the micropumps. That is, it is possible to physically desorb the contaminants adsorbed on the soil by the strong collision wave generated by colliding with each other as the water molecules surrounding the minute bubbles collide with each other. In addition, it is possible to decompose other contaminants by a chemical reaction due to the oxidizing power of OH radical and H ₂ O ₂ generated at instantaneous high temperature and high pressure condition.

A skimmer can be installed on the upper part of the pressurized floating tank to separate floating contaminants, and the purified soil purified through the pressurized floating tank is transferred to the sand unit.

On the other hand, the dissolution processor 340 performs a function of chemically dissolving heavy metals and other contaminants in the magnetic contaminated soil selected by the magnetic force selector 310. The elution processing apparatus 340 may include a reservoir reservoir 344 for a three-stage structure, a pH adjustment reservoir 345, and a reservoir 346 for the three-stage structure 341, 342, and 343. 343 and 343 of the three-stage structure are formed by mixing the magnetic contaminated soil with the leaching agent to elute the heavy metal, and the primary leaching tank 341, the secondary leaching tank 342 and the tertiary leaching tank 342 343). The elution step can be stepwise eluted to increase the elution efficiency. In the present embodiment, although three stages of the casting tank are used, one or more casting tanks can be used, and it is preferable to increase the number of stages to increase the treatment efficiency. Each elution tank has a stirring tank so that the soil and eluent can be mixed. The eluent reservoir 344 stores the eluent to be supplied to the elution tank, and the eluent can be supplied to the elution tank by the connected supply pump. The leaching agent used herein may include sulfuric acid or hydrochloric acid. The pH adjusting tank 345 functions to neutrally neutralize the pH adjusting agent after elution. The pH adjustment tank may be connected to a pH adjuster reservoir capable of storing a pH adjusting agent (e.g., NaOH) and supplying it to the pH adjusting tank. The reservoir stores the neutralized soil in the pH adjustment tank and the eluent mixture, and transfers the purified soil to the sand unit.

The sand unit 350 functions to separate water and soil from the pressurized floating tank and the purified soil supplied from the storage tank. For example, as in the third sorting device, the purified soil of about 0.075 to 2 mm is separated from the water through the screen. Here, the water component may be connected to the water treatment unit so that the water component can be treated through the water treatment unit since the pollutant is present.

Hereinafter, a method for treating heavy metal contaminated soil according to an embodiment of the present invention will be described in detail. 4 is a process diagram of a method for treating heavy metal contaminated soil according to an embodiment of the present invention. As shown in FIG. 4, the heavy metal contaminated soil treatment method according to an embodiment of the present invention includes a particle size selection process (S10), a water treatment process (S20), and a soil purification process (S30).

The particle selection process (S10) is a process in which the soil contaminated with heavy metals is supplied to separate gravels having a minimum particle size of lumps and gravels having a minimum particle size of greater than or equal to the minimum particle size and to remove polluted soil between the minimum particle size and the minimum particle size And discharge them selectively. First, the contaminated soil is supplied through the feed hopper to heavy metals. The first sorting machine installed under the feed hopper vibrates and dry-drains the lumps having an average particle size of at least 50 mm or more of the minimum particle size and discharges them (first screening process). After the rubble is discharged, the contaminated soil having an average particle size of less than 50 mm is moved through the conveyor belt, and the gravel having an average particle size of about 5 mm or more and the minimum particle size of the average particle size is separated through the second sorter (second screening process). In the selection process, the lumps and gravel contained in the contaminated soil are heavy metals, and the pollutants are hardly combined, so that they can be recycled immediately, thereby separating the usable lumps and gravel from the contaminated soil.

After the gravel is selected, the contaminated soil is separated into clean soil which can be recycled after purification treatment, and micro-soil which is less than the purification minimum particle, which is remarkably low in polluted soil between the minimum particle size and gravel minimum particle size. (Cyclone screening process) The fine soil having an average particle diameter of less than 0.075 mm in the contaminated soil through the cyclone device is contained in the upper drainage water together with water and can be recycled as an aggregate after the purification treatment. . In order to improve the screening efficiency, the multi-cyclone that minimizes the size of the cyclone is applied, and the efficiency of separation can be improved by applying the multi-cyclone. In the embodiment of the present invention, a first cyclone is used in a two-stage cycle, and a multi-cyclone in which four cyclones are arranged in parallel is used as a second cyclone.

The fine soil contained in the contaminated soil subjected to the cyclone sorting process can be further separated through the third separator (third sorting process). This third sorting process is a process for preventing the micro-soil having low purification efficiency from being included in the subsequent process.

After separating the contaminated soil having an average diameter of about 0.075 to 5 mm and the fine soil having an average diameter of less than 0.075 mm through the cyclone sorting process, the polluted soil is removed and recycled through the purification process (S30) Is flocculated through the water treatment process (S20), and discharged in a state of being easily buried.

In the purification process (S30), it is essential that the contaminated soil is separated into magnetic contaminated soil and non-magnetic contaminated soil through magnetic force. Heavy metals in the soil are correlated with magnetic susceptibility due to the existence of oxide minerals such as hematite and magnetite. In particular, cadmium, chromium, copper, nickel, and zinc, which are classified as pollutants in the Soil Environment Conservation Law, have a relatively high autonomy. Therefore, in the case of separation into magnetic contaminated soil and non-magnetic contaminated soil through magnetic force, heavy metal pollutants are strongly chemically bonded to the soil when they are magnetized, and non-magnetic contaminated soil is relatively weakly bonded to the soil, It is possible not only to increase the purification efficiency in the treatment but also to recycle the heavy metal contaminated soil at a lower cost than in the past. The magnetic force selection process can be applied through permanent magnets of about 3000 Gauss. In the case where fine grains having an average particle diameter of less than 0.075 mm are contained in the magnetic separation process, the fine grained soil is negatively charged, which may lower the magnetic separation efficiency. Therefore, after the cyclone sorting process for separating the fine grains, The efficiency can be improved.

The magnetic contaminated soils separated through the magnetic separation process have a large amount of heavy metal contaminants strongly chemically bound to the soil, so they are eluted to remove heavy metal contaminants. Sulfuric acid, hydrochloric acid or phosphoric acid may be used as the eluent to be used at this time. As in the case of the embodiment of the present invention, when a three-stage drying tank is used, an eluent with a pH of about 1 is supplied to the first elution tank and the third elution tank, . In each tank, thoroughly agitate using a stirring device so that the solvent and the soil are mixed well. The pH adjustment tank is moved from the tertiary use tank to the pH adjustment tank. A variety of alkali materials such as sodium hydroxide may be used as the pH adjuster used at this time. The purified soil is transferred to the sand unit in the storage tank to remove moisture from the purified soil and separate and store it. The purified soil thus stored can be recycled as aggregate.

Since the non - magnetic contaminated soil separated through the magnetic separation process is weakly bound to the soil by the heavy metal contaminant than the magnetic contaminated soil, the heavy metal contaminant is removed through the pressurized float after physically breaking down. If this process is performed, it is possible to simplify the separation through the process without using the extraction agent and to save the cost. First, it is physically shredded through a crusher to remove heavy metal contaminants attached to non-magnetic contaminated soil. According to the present invention, contaminants are separated through friction between the rotary driving blades and the blades through the blades. After crushing through a crusher, the soil is floated up by pressurized float treatment and separated through a skimmer. The purified soil is transferred to a sand unit to remove moisture and then to be separated and stored. The stored purified soil is recycled as aggregate It is possible. At this time, it is preferable to use fine bubbles of 0.1 to 10 mu m for the pressurized floating treatment. When the microbubbles are treated, the rate of rise in the water becomes slow and the residence time of the bubbles becomes long and the specific surface area becomes large, so that the adsorption power of the gas-liquid interface becomes high, which is advantageous for the movement of contaminants. In addition, the OH - (hydroxide ion) is collected at the interface and the surface is charged with (-), so that the adhesion of the heavy metal to the cation can be increased.

The water treatment step S20 is a step of mixing the fine soil with a polymer flocculant and separating and discharging the fine soil. Through the particle size selection process, the separated fine soil is converted to a sedimentation tank in the form of muddy water mixed with water. The polymer flocculant is added to the sedimentation tank to aggregate the colloidal soil so that it sinks downward by gravity. The concentrate is moved and concentrated and the water is transferred to the collection channel. The concentrated black in the concentration tank is dehydrated in the filter press and is treated as a cake, and the filtrate is transferred to the settling tank again. The water separated from the concentration tank is transferred to the collection channel, transferred to the flow control tank through the filtration tank, and can be used as the process water.

Hereinafter, a method for treating heavy metal contaminated soil according to the present invention will be described in more detail with reference to the following experimental examples.

1. Measurement of heavy metal pollutant concentration by particle size

The pollution level of polluted soil by the representative domestic livestock wastewater was selected and the pollution level of heavy metals was determined according to the particle size. The weight ratios according to the particle size and the content ratios of representative heavy metals such as copper (Cu), zinc (Zn) and cadmium (Cd) are shown in Table 1 below.

Particle size classification
(mm) Weight ratio
(wt.%) Cu (mg / kg) Zn (mg / kg) Cd (mg / kg) 5.00 or higher 12.9 130.5 197.4 2.87 4.75 ~ 0.84 18.5 335.3 687.0 4.67 0.84 to 0.25 40.2 333.3 697.2 4.96 0.25 to 0.075 15.3 387.5 673.7 5.14 0.075 to 0.037 9.3 425.4 927.5 8.25 0.037 or less 3.8 448.7 941.1 8.65

As shown in Table 1, soil of 5.00 mm or more in particle size is low in pollution level, but it can be immediately recycled, but it is found that the pollutant is concentrated in microsoil of less than 0.075 mm.

2. Measurement of cyclone separation efficiency

The micro-soil separation efficiency according to the apparatus arrangement of the hydrocyclone, that is, the micro-soil content remaining after the treatment of less than 0.075 mm in particle size is shown in Table 2 below.

How to separate Screening Single Cyclone Separation Efficiency Multistage Cyclone Separation Efficiency Multi-stage + multi-cyclone separation efficiency Fine soil content less than 0.075mm in particle size
(Weight ratio wt%) 13.1% 5.04% 3.10% 2.14% Separation efficiency (%) - 61.5% 76.3 83.6

As shown in Table 2, the content of fine soil with a particle size of less than 0.075 mm was 13.1%, and the separation efficiencies were 61.5% for single cyclone, 76.3% for multistage cyclone, And multi-stage + multi-cyclone was the best at 83.6%. The application of the hydrocyclone is a low-cost continuous apparatus, and it is possible to separate the fine soil most efficiently when multi-stage + multi-cyclone is applied. In this experiment, the multi-stage cyclone is a two-stage cyclone apparatus, and the multi-cyclone uses a cyclone apparatus in which four cyclones are connected in parallel.

3. Measurement of heavy metal pollutant concentration by magnetic force sorting

The concentrations of heavy metal contaminants before and after magnetic force sorting for contaminated soils of 0.075 to 5 mm in particle size are shown in Table 3 below.

division Cu
(mg / kg) Zn
(mg / kg) CD
(mg / kg) A magnetic line 411.8 878.9 6.54 After magnetic force sorting Magnetic contaminated soil 528.5 1085.6 8.69 Non-magnetic contaminated soil 302.5 689.7 4.92

As shown in Table 3, when the magnetic force was selected, it was found that about 1.3 times heavy metals were concentrated.

4. Measurement of Heavy Metal Contamination Concentration after Purification by Crushing and Pressurization

First, recovery rates and heavy metal pollutant concentrations are shown in Table 4 when there is a crushing process and when there is no crushing process.

division Soil particle recovery (%) Cu
(mg / kg) Zn
(mg / kg) CD
(mg / kg) If there is no shredding process Raw sample - 302.5 689.7 4.92 Wound sample 8.60 415.2 623.4 5.98 Sedimentation sample 91.40 244.3 575.4 3.25 If you have a shredding process Raw sample - 302.5 689.7 4.92 Wound sample 15.90 598.4 758.7 6.54 Sedimentation sample 84.10 204.7 514.8 2.35

As shown in Table 4, the recovery rate and the contamination concentration are different in the case of and without the crushing process, and it is necessary to apply the crushing process.

Table 5 shows recovery rates and heavy metal pollutant concentrations depending on the size difference of the bubbles in the pressurized floating process. Herein, micro bubbles refer to bubbles having a size of 0.1 to 10 μm, and general bubbles refer to bubbles having a size of several tens of μm.

division Soil particle recovery (%) Cu
(mg / kg) Zn
(mg / kg) CD
(mg / kg) Fine bubble Raw sample - 341 779.2 1.025 Wound sample 8.60 698.7 126.1 2.223 Sedimentation sample 91.40 318.7 789.4 1.258 Plain bubble Raw sample - 341 779.2 1.025 Wound sample 5.90 563.32 695.15 2.051 Sedimentation sample 94.10 335.51 714.63 1.021

In the case of ordinary bubbles, it is difficult to rise the solid content dispersed in the inside because it ruptures with a rapid rise. However, in the case of fine bubbles, the rising speed is slow and the specific surface area can be made large. Therefore, it can be seen that the recovery rate of the floating sample is high when the microbubbles are used.

5. Concentration change of heavy metal contaminants after elution treatment

The concentrations of heavy metal contaminants after the elution treatment on the contaminated soil are shown in Table 6 below.

division Cu
(mg / kg) Zn
(mg / kg) CD
(mg / kg) Before application 528.5 1085.6 8.69 Stage 1 380.5 922.8 5.65 Step 2 200.8 597.1 3.91 Step 3 185.0 412.5 4.08

As shown in Table 6, it can be seen that the concentration of the heavy metal contaminant decreases as the elution step increases.

FIG. 5 is a view illustrating a result of heavy metal contamination measurement according to a method of treating heavy metal contaminated soil according to an embodiment of the present invention. As shown in FIG. 5, after the particle size selection process in the raw sample, the separation treatment through the magnetic force separation showed that the concentration of the heavy metal contaminant was remarkably lowered.

While the present invention has been described in connection with what is presently considered to be practical exemplary embodiments, it is to be understood that the invention is not limited to the disclosed embodiments, but, on the contrary, You will understand.

It is therefore to be understood that the above-described embodiments are illustrative in all aspects and not restrictive. The scope of the present invention is defined by the appended claims rather than the detailed description, and all changes or modifications derived from the meaning and scope of the claims and their equivalents should be interpreted as being included in the scope of the present invention .

100: particle size selection unit 110: feed hopper 120: sorting unit
121: first selector 122: second selector 130: cyclone device
131: first cyclone 132: second cyclone 140: third selector
200: Water treatment section 210: Collecting tank 220:
221: Polymer flocculant storage tank 230: Enrichment tank
240: Filtration tank 250: Flow adjustment tank 260: Filter press
270: filtrate reservoir 300: soil remover 310: magnetic separator
320: crushing tank 330: pressurized floating tank 340: elution treatment apparatus
341: Primary usage 342: Secondary usage 343: Third usage
345: pH adjusting tank 346: storage tank 350: sand unit

Claims (23)

A soil sorting unit for sorting and discharging contaminated soil between the minimum particle size of the purifying minimum particle size and the minimum particle size of the purifying soil, ,
A water processor for purifying and discharging the fine soil selected by the particle size selector;
The contaminated soil selected by the particle size selecting unit is separated through magnetic force to elute the magnetic contaminated soil, the non-magnetic contaminated soil is crushed and floated, the soil subjected to the elution treatment or floating treatment is separated from the soil And a purifying section,
The soil remover includes a magnetic separator for separating the contaminated soil that has passed through the particle size discriminating unit into a magnetic contaminated soil having magnetism and a non-magnetic contaminated soil having non-magnetic property by adding magnetic force, a crusher for physically crushing non- A pressurized flotation tank for flushing the non-magnetic contaminated soil crushed through the crusher by floating the contaminants through the fine bubbles, a leaching treatment device for separating the heavy metals by reacting the magnetic contaminated soil with the leaching agent, And a sand unit for separating the contained water of the purified soil purified through the treatment apparatus,
Wherein the particle size selector comprises a feed hopper for supplying soil contaminated with heavy metals, a sorting unit for separating gravel or gravel having a minimum size of gravel by treating the soil supplied through the feed hopper, and treating the soil passing through the sorting unit for purification And a cyclone device for separating the fine soil less than the minimum particle size,
The sorting unit includes a first sorter for treating the soil supplied through the feed hopper to separate gravels having a size of the minimum particle size of the rubble, a second separator for separating the gravels having a minimum size of gravel by processing the soil having passed through the first sorter, And a third separator for separating the fine soil contained in the contaminated soil that has passed through the cyclone apparatus and having a pore size smaller than the purifying minimum particle size,
Wherein the leaching treatment apparatus comprises: a leaching tank for leaching the chemically bound heavy metal by mixing the magnetic contaminated soil with the leaching agent; a storage tank for storing the purified soil purified in the leaching tank and discharging the purified soil to the sand unit; And a pH adjustment tank for adjusting the pH of the purified soil,
The crusher includes a blade for rotating the non-magnetic contaminated soil to be charged, a motor for driving the blade to rotate, and a tip provided at the tip of the blade for separating contaminants from non- / RTI >
The water treatment unit includes a sedimentation tank in which the fine soil flows into the sedimentation tank, which is flocculated, precipitated and discharged by the polymer flocculant, a concentrated tank in which the fine soil discharged from the sedimentation tank flows in and is concentrated, And a filter press for removing the filter press,
Wherein the average particle size of the rubble is 50 mm or more, the average particle size of the gravel is 5 to 50 mm, the average particle size of the contaminated soil is 0.075 to 5 mm, and the average particle size of the fine soil is less than 0.075 mm. Soil treatment system.
delete delete The method according to claim 1,
Wherein the cyclone apparatus comprises at least one hydrocyclone.
delete delete delete delete delete The method according to claim 1,
Wherein the pressurized floatation vessel includes an ultrasonic generator capable of generating ultrasonic waves at a lower portion and transmitting vibrations thereof.
The method according to claim 1,
And a skimmer installed on the upper portion of the pressurized floating tank to remove floating contaminants.
delete Removal of gravels with a minimum particle size of liquor and pebbles of minimum gravel size or more with a heavy metal contaminated soil and separation of fine gravels below the minimum purification particle size and purifying soil between minimum purification particle size and gravel minimum particle size process,
A water treatment process for purifying and discharging the selected fine soil in the particle size selection process, and
The separated contaminated soil is separated by magnetic force, the separated magnetic contaminated soil is eluted, the non-magnetic contaminated soil is crushed and floated, and the eluted or floated soil is separated from water And recovering the soil,
The soil remediation process includes a magnetic force selection process of separating the polluted soil selected in the particle size selection process into magnetic polluted soil and non-magnetic polluted soil through magnetic force, magnetic separation of the magnetic polluted soil separated by the magnetic separation process, An elution process of eluting the soil heavy metals, a pulverizing process of physically crushing the non-magnetic contaminated soil, a pressurized floating process of floating the non-magnetic contaminated soil through the micro-bubbles through the pulverization process, And a water removing step of removing moisture of the purified soil after the pressurized floating process,
The particle sorting process includes a first sorting process of receiving soil contaminated with heavy metals and separating lumps having a minimum particle size of the rubble, a second sorting process of separating the gravels having a minimum particle size of the gravel by treating the soil subjected to the first sorting process A cyclone sorting process for separating the fine soil having a pore size smaller than the minimum pore size through the cyclone apparatus, and a step for separating the fine soil having the pore size smaller than the minimum pore size contained in the polluted soil subjected to the cyclone sorting process And a third selection process,
The soil remediation process further includes a pH control process of neutralizing the purified soil after the elution process by adding a pH adjusting agent thereto,
In the water treatment process, the polymer flocculant is added to the micro-soil to flocculate and precipitate the water, and then the water is removed after concentration.
Wherein the average particle size of the rubble is 50 mm or more, the average particle size of the gravel is 5 to 50 mm, the average particle size of the contaminated soil is 0.075 to 5 mm, and the average particle size of the fine soil is less than 0.075 mm. Soil treatment method.
delete delete delete delete delete delete 14. The method of claim 13,
The above-mentioned eluent is a method for treating a heavy metal contaminated soil containing sulfuric acid, hydrochloric acid or phosphoric acid
14. The method of claim 13,
Wherein the pH adjusting agent is sodium hydroxide.
14. The method of claim 13,
Wherein the bubbles in the pressurized flotation process are microcapsules of 0.1 to 10 mu m.
23. The method of claim 22,
And the ultrasonic vibration is added in the pressurized float process.

Images