KR101270065B1 - Chemistry washing method - Google Patents

Abstract

PURPOSE: A heavy metal contaminated soil washing method is provided to enhance the washing efficiencies, reduce the cost and reduce the generation of sludge. CONSTITUTION: A heavy metal contaminated soil washing method comprises the following steps: (S1) classifying polluted soil by particle sizes and washing the classified polluted soil by circulating process water; (S2) washing the polluted soil aggregates using chemicals, a high speed agitator, and a jet mill; (S3) repeatedly spraying and washing the polluted aggregates; and (S4) precipitating minute polluted soil by particle sizes and sludge processing. The previous step (S1) comprises the following steps: washing aggregates with a size of 40mm or greater after sieving by a screen; agitating the aggregates with a size of 40mm or less with the processing water; isolating the agitated processing water into the polluted soil with a size of 1mm or greater and aggregates with a size of 1mm or less; sprinkle washing the aggregates with a size of 1mm and dehydrating and discharging the same; supplying the aggregates with a size of 1mm or less and processing water to an adjusting bath; supplying the aggregates with a size of 1mm and the processing water from the adjusting bath to hydrocyclone; and delivering the graded soil in the hydrocyclone to a chemistry washing tub and delivering the processing water to a log washer. [Reference numerals] (S1) Circulation washing step; (S2) Chemical washing step; (S3) Continuous washing step; (S4) Sediment soil processing step

Description

Heavy Metal Contaminated Soil Cleaning Method {Chemistry Washing Method}

The present invention relates to a heavy metal contaminated soil washing method, and more particularly, by separating the contaminated soil by aggregate, and chemically cleaning and circulating the washing water used for chemical washing to supply it again, thereby improving washing efficiency and reducing costs. The present invention relates to a heavy metal contaminated soil cleaning method.

In case of soil pollution, once contaminated, it may adversely affect the surface water and groundwater quality, causing secondary pollution to the surrounding environment. Therefore, contaminated soil must be purified and restored at the site as soon as possible.

In view of the above, the soil washing technique was first developed in the United States in the late 1970s and is currently one of the most frequently used patent technologies in many countries, including the United States, Germany and the Netherlands. Extensive

Due to its wide range of applications, it is recognized as one of the most efficient and economically efficient purification methods in view of the current situation in which a large amount of various organic pollutants and heavy metals are emitted.

Recently, soil pollution in various oil handling plant areas including oil refineries has been a serious social problem, and efforts have been made to efficiently excavate and restore such soils.

In general, soil washing techniques can be largely divided into Ex-situ washing method and In-situ washing method.

The ex-situ washing technique is also commonly referred to as soil washing, and after grasping the distribution of substances in soil and physical / chemical characteristics of the soil to excavate the contaminated soil in the treatment range, it is contaminated using an appropriate washing solution. Soil washing method can be divided into on-site treatment and off-site treatment.

The in-situ washing technique circulates the washing water in the soil by installing a washing solution injection well, a washing solution discharge well, a effluent treatment facility, a pump and instrumentation facility, and a volatile material treatment facility without polluting the soil. The treatment time is long, and the soil voids are clogged, which makes it difficult to recover the washing solution in the washing apparatus.

Soil washing technique depends on the degree of mixing of soil with pollutants, particle size distribution and specific gravity.

Here, the soil washing is specifically put contaminated soil with the wash water to wash through pressure, vibration, rotation and stirring, and passed through the screen of the mesh (網狀) to separate the washed soil particles and the wash water to wash the soil Since the soil is basically separated from the washing water by the screen, only soil having a predetermined particle size or more is collected, and soil having a particle size of less than that is discharged together with the washing water.

Therefore, a method of constructing a plurality of soil washing devices in stages or constructing a screen in the soil washing apparatus in multiple stages by particle size is applied, and a sorting device or a dewatering device for classifying soils of various particle sizes constituting soil is also basically operated. Since the method is similar to the above-described soil washing apparatus, the sorting apparatus, the soil washing apparatus, and the dehydration apparatus are mixed in the actual soil washing process.

Recently, the method of restoring and cleaning contaminated soil has been disclosed after patent application of the Korean Patent Publication No. 10-2010-0077497 (Repairing and cleaning method of soil contaminated with residual organic compounds and heavy metals). It improves washing efficiency by reducing the cost and improves the washing efficiency by circulating and supplying the washing water injected into the water, and improves the washing efficiency by sprinkling and dehydrating pollutants contained in the soil by continuously washing the soil discharged after chemical washing. The technology to reduce sludge generation by separating the sediment of fine soil settling in the sand by the particle diameter and coagulating and dehydrating is continuously developed.

The present invention was developed to meet the demands of the times, the object of the present invention is to separate the polluted soil by aggregate and to wash and to supply again by circulating the washing water used for washing, improving the cleaning efficiency and cost The purpose of the present invention is to provide a method for washing heavy metal contaminated soil, which is reduced, and continuously sprayed and dehydrated.

Another object of the present invention is to continuously clean the contaminated soil of the fine powder discharged after washing to wash the contaminants contained in the fine powder, and also to separate the soil of fine powder sedimented after chemical washing by particle size to agglomerate and dehydrate to reduce sludge generation. Another purpose is to provide a heavy metal contaminated soil cleaning method.

According to the present invention, after the soil is classified by particle diameter, the process water is circulated to be supplied to the process, and the circulating washing step of washing the classified soil and the circulating washing aggregate are repeatedly washed and dehydrated through the chemical washing step. The sedimentation soil treatment step of separating and dewatering the contaminated soil of fine powder transferred to the sedimentation tank through the continuous washing step and the chemical washing step is characterized in that it consists of.

In addition, the washing step is to put the process water and contaminated soil in the log washer having a screen on the top, the contaminated soil is the aggregate of more than 40mm particle is washed by the screen, the aggregate is less than 40mm aggregate aggregate A stirring process for stirring with the process water and a process water stirred in the log washer and a contaminated soil are supplied to a dewatering screen by a paddle provided inside the washer and separated therein to separate aggregates of 1 mm or more and aggregates of 1 mm or less. The separation process and the discharge of more than 1mm aggregate from the dewatering screen to the belt conveyor to send to the finished soil and the process of supplying less than 1mm aggregate and process water from the dewatering screen to the control tank and aggregate less than 1mm to the hydrocyclone in the adjustment tank And the process for supplying the process water and the aggregate delivered from the adjusting tank is delivered to the chemical washing tank, the process water The cycle consisting of the step of transfer into the next log washer is characterized.

In addition, the continuous washing step receives the aggregate washed in the chemical washing tank, the first sand washing step of washing and dehydrating after washing with the washing water on the first vibrating screen, and the second vibration of the aggregate after the first sand washing process again It is characterized by consisting of a second sand washing step of dehydration after washing with washing water in the screen.

In addition, the step of treating the sedimentation soil is a step of supplying the process water containing the fine particles of contaminated soil from the chemical cleaning tank to the settling tank and supplying it to the chemical reaction tank and the settling auxiliary tank according to the particle size of the fine particles included in the process water. And the process water is supplied from the chemical reaction tank to the first high-speed agglomeration concentrate tank, and a coagulant is supplied to coagulate the microparticles contained in the process water, and then the coagulated microparticles are fed through the first filter press. The process water is discharged and the process water is supplied from the sedimentation auxiliary tank to the second high-speed agglomeration concentration tank, and a coagulation agent is supplied to agglomerate the microparticles contained in the process water, and the coagulated microparticles are collected. Discharging through a filter press, and the first settling tank and the first settling tank in the first and second high Supplying process water to each of the two settling tanks to precipitate the fine particles, and then supplying the precipitated fine particles of the first settling tank and the second settling tank to the first high-density concentrating tank and the second high-density concentrating tank again; After moving the process water of the first settling tank and the second settling tank to the collecting tank, it is characterized in that the step consisting of flowing into the process water tank through the filtration tank.

Heavy metal contaminated soil washing method of the present invention is to separate the contaminated soil by aggregate, and to wash and supply again by circulating the washing water used for washing, improving the cleaning efficiency and reduce the cost.

In addition, by continuously washing the aggregate discharged after the chemical cleaning to wash the contaminants contained in the aggregate, and also to separate the contaminated soil of fine dust settled after the chemical cleaning by particle diameter, there is an effect to reduce the sludge generation.

1 is a block diagram showing the procedure of the heavy metal contaminated soil washing method according to the present invention.
2 is a view showing a circulating washing step and a chemical washing step according to the heavy metal contaminated soil washing method according to the present invention.
3 is a block diagram showing a continuous washing step according to the heavy metal contaminated soil washing method according to the present invention.
Figure 4 is a schematic diagram showing a continuous washing step according to the heavy metal contaminated soil washing method according to the present invention.
5 is a view showing the sedimentation soil treatment step in the heavy metal contaminated soil washing method according to the present invention.

Hereinafter, with reference to the accompanying drawings will be described a preferred embodiment of a heavy metal contaminated soil washing method according to the present invention with reference to the accompanying drawings. In this process, the thicknesses of the lines and the sizes of the components shown in the drawings may be exaggerated for clarity and convenience of explanation. In addition, the terms described below are defined in consideration of the functions in the present invention, and this may vary depending on the intention or custom of the user, the operator. Therefore, definitions of these terms should be made based on the contents throughout this specification.

In addition, the following embodiments are not intended to limit the scope of the present invention, but merely as an example, and various embodiments may be implemented through the present invention.

1 is a block diagram showing the order of the heavy metal contaminated soil washing method according to the invention, Figure 2 is a view showing a circulating washing step and a chemical washing step according to the heavy metal contaminated soil washing method according to the invention, Figure 3 In the heavy metal contaminated soil washing method according to the present invention, is a block diagram showing a continuous washing step according to, Figure 4 is a schematic diagram showing a continuous washing step according to the heavy metal contaminated soil washing method according to the invention, Figure 5 In the heavy metal contaminated soil washing method according to the invention, it is a view showing the step of washing the soil.

As shown in the drawings, the present inventors heavy metal contaminated soil washing method (hereinafter referred to as contaminated soil washing method for convenience of description) is to classify the contaminated soil by particle size and to configure the process water to be circulated supply to wash the contaminated soil Circulating washing step (S1) and the continuous washing step (S3) to repeatedly spray and wash through the chemical washing step (S2) and the chemical cleaning step (S2) and the chemical cleaning step of the soil contaminated through the washing step (S1) and It consists of a sedimentation soil treatment step (S4) for washing the contaminated soil of fine powder moved to the sedimentation tank through the chemical washing step (S2).

The washing step (S1) is to put the process water and contaminated soil to the upper screen 120 to the upper screen 120 and the lower log washer 110, the log washer 110 having a stirring space in the lower soil contaminated And the process water is stirred. Aggregate with a particle diameter of 40 mm or more included in the contaminated soil is filtered out by the screen 120 and then washed by water sprayed from the upper part of the screen, and an aggregate having a particle diameter of 40 mm or less passes through the screen and the log washer. (110) a paddle (Paddle) made of a rotating shaft provided in the inside and a plurality of agitating blades formed on the rotating shaft is stirred with the process water and is moved through the stirring process, the log washer 110 Agitated process water and contaminated soil in the) is moved to the dewatering screen 130 is subjected to a separation process of separating more than 1mm aggregate and less than 1mm aggregate passed through the dewatering screen 130.

Then, the aggregate of 1mm or more separated from the dewatering screen 130 is sent to the finished soil via the belt conveyor 180, the soil and process water of 1mm or less passed through the dewatering screen 130 to the adjustment tank 150 After the process of supplying and supplying the soil and the process water of 1mm or less from the adjusting tank 150 to the hydrocyclone 170 through the transfer pump 160, and classifies the liquid-liquid, and the process water exiting from the cyclone 170 again It is delivered to the log washer 110 and the chemical cleaning tank 140 to circulate, and delivers the soil of 1 mm or less classified in the cyclone to the chemical cleaning tank 140, and delivers the contaminated soil to the chemical cleaning tank for chemical cleaning. In addition to performing the washing step (S2) it can be supplied to the log washer 110 by circulating the process water. At this time, the above-mentioned process water is moved to include the fine powder of less than 1mm that is not classified after the solid-liquid classification in the cyclone.

At this time, the chemical washing tank 140 has a plurality of stirring chambers therein and by stirring the process water, contaminated soil and chemicals introduced from each stirring chamber through a high speed stirrer, to increase the residence time of the contaminated soil In order to improve the cleaning efficiency, the contaminated soil has a higher concentration as compared to the soil having a larger particle size, so that it is preferable to circulate the soil having a small particle size to lengthen the washing time.

In addition, a jet mill is provided inside the stirring chamber to discharge the compressed air delivered from the outside through nozzles disposed to face each other, thereby colliding with the soil particles to separate the contaminants of the particles.

The continuous washing step (S3) is less than the contaminated soil of fine powder, the washing area is less than 1mm of aggregates, the cleaning efficiency is supplied from the chemical washing tank and the cleaning soil is finished, the finished soil As to form, such a continuous washing step (S2) is a solid-liquid classification of the soil in the sand No. 1 cyclone 220 installed in the upper part in the chemical washing tank is supplied to the sand No. 1 vibrating screen 210 and washed with washing water and then vibrated After the first sand washing process for dehydration, the second sand washing process is applied to the second vibrating screen 230 by the second cyclone 240 to wash the soil after the first sand washing process, and then washed with washing water, followed by the second sand washing. Aggregate made by the process, the second sand washing process is completed as a complete soil, is moved to the belt conveyor and deposited, depending on the aggregate and use of the building after the soil purification verification It is also possible to backfill.

At this time, the size of the soil supplied to the sand primary vibrating screen 210 in the chemical washing tank is not limited to 1 mm, and may also supply aggregates smaller or larger than 1 mm depending on the type of soil and the degree of contamination.

The immersion soil washing step (S4) is a chemical reaction tank 320 according to the particle size of the fine particles contained in the process water after receiving the process water containing the fine particles of contaminated soil from the chemical washing tank to the immersion tank (310) And after receiving the process water from the chemical reaction tank 320 to the first high-speed condensing concentration tank 321 and agglomerating fine particles contained in the process water. After supplying the flocculant and condensing at high speed, the flocculated concentrated floc is discharged to the outside in the form of sludge through the first filter press 322.

Thereafter, the process water is supplied from the sedimentation auxiliary tank 330 to the second high speed agglomeration concentration tank 331, and a coagulant is supplied to the micro agglomerates to aggregate the fine particles contained in the process water. The fine particles are discharged through the second filter press 332, and the first settling tank 323 and the second settling tank 321 and the second set of high-density condensing tank 331 333) is supplied with the process water, respectively, and the remaining fine particles contained in the process water are precipitated for a predetermined time, and then the precipitated fine particles of the first precipitation tank 323 and the second precipitation tank 333 are again present. After passing through the process of supplying to the high speed concentration tank 321 and the second high speed concentration tank 331, the process water of the first precipitation tank 323 and the second precipitation tank 333 is moved to the collecting tank 340. After entering the process water tank 360 through the filtration tank 350 By doing so, a series of contaminated soil cleaning processes are completed.

As described above, in the sedimentation soil treatment step (S4), by dividing according to the particle size of the contaminated aggregate included in the process water into the chemical reaction tank or the sedimentation auxiliary tank 330, it is possible to maximize the washing efficiency.

At this time, it is also possible to install a plurality of the sedimentation auxiliary tank (330, 330 ') to be supplied to each of the high-speed aggregation concentration tank (321, 331) after supplying the aggregate, respectively, according to the particle size or the degree of contamination of the contaminated aggregate.

Preferably, the process water filtered by the filtration tank and introduced into the process water tank may be recycled by being supplied to the log washer again with the process water supplied from the outside.

S1: circulating washing step S2: chemical washing step
S3: Continuous washing step S4: Sedimentation soil treatment step
110: lock washer 120: screen
130: dewatering screen 140: chemical cleaning tank
150: adjustment tank 160: transfer pump
170: cyclone
210: 1st vibration screen 220: 1st cyclone pump
230: 2nd vibrating screen 240: 2nd cyclone pump
310: sedimentation tank 320: chemical reaction tank
321: first high speed condensation concentration tank 322: first filter press
323: 1st sedimentation tank 330,330 ': sedimentation auxiliary tank
331: 2nd high speed condensation concentration tank 332: 2nd filter press
333: second settling tank 340: collecting tank
350: filtration tank 360: process water tank

Claims (4)

After classifying the contaminated soil by particle size, the process water is circulated and supplied to clean the classified soil and the contaminated soil aggregate after the circulation washing step is cleaned by chemical, high speed stirrer, and jet mill. Continuous washing step of repeatedly spraying and washing the contaminated soil aggregate after the chemical washing step and the chemical washing step and the fine soil contaminated by fine particles transferred to the sedimentation tank through the chemical washing step by sedimentation by sludge treatment Soil washing stage,
The circulation washing step is to put the process water and contaminated soil in a log washer having a screen on the top, the contaminated soil is the aggregate of more than 40mm particle is filtered by the screen and washed, the aggregate of less than 40mm is the log washer A stirring step of stirring with the process water by a paddle (Paddle) is introduced into the inside;
Separating process of separating the aggregate of more than 1mm and aggregate less than 1mm by receiving the process water and contaminated soil stirred in the log washer to the dewatering screen;
Spraying the aggregate of 1 mm or more from the dewatering screen by sprinkling cleaning, and then draining it to a belt conveyor;
Supplying aggregate and process water of 1 mm or less from the dewatering screen to an adjustment tank;
Supplying aggregate and process water of 1 mm or less to the hydrocyclone in the adjusting tank; And
Aggregate delivered from the adjustment tank is made of a circulating process to deliver the soil classified in the hydrocyclone to the chemical washing tank, the process water is again delivered to the log washer,
The saline soil washing step includes the step of receiving the process water containing the fine particles of contaminated soil from the chemical washing tank and supplying it to the chemical reaction tank and the salivary auxiliary tank according to the particle size of the fine particles included in the process water;
The process water is supplied from the chemical reaction tank to the first high-speed aggregating tank, and a coagulant is supplied to agglomerate the fine particles contained in the process water, and the coagulated microparticles are discharged through the first filter press. Making process;
The process water is supplied from the sedimentation auxiliary tank to the second high-speed agglomeration concentrate tank, and a coagulant is supplied to agglomerate the fine particles contained in the process water, and then the high-density agglomerated microparticles are collected through a second filter press. Discharge process;
Receiving the process water from the first high-speed agglomeration concentration tank and the second high-speed agglomeration concentration tank to the first settling tank and the second settling tank, respectively, precipitates the fine particles, and again precipitates the fine particles of the first settling tank and the second settling tank. Supplying the first high speed condensation concentration tank and the second high speed condensation concentration tank; And
The process of washing the heavy metal contaminated soil comprising the step of moving the process water of the first settling tank and the second settling tank to a collection tank and then flowing the process water into a process water tank.
delete The method of claim 1,
The continuous washing step is a first sand washing process for receiving the aggregates washed in the chemical washing tank washing with deionized water on the first vibrating screen and then dehydrating,
The heavy sand contaminated soil washing method comprising the second sand washing step of washing the aggregate after the first sand washing step again with the washing water in the second vibrating screen.
delete

Images