WO2017071104A1

WO2017071104A1 - Combined soil washing desorption method and device

Info

Publication number: WO2017071104A1
Application number: PCT/CN2016/000013
Authority: WO
Inventors: 杨强; 孙荣江; 刘懿谦; 林匡飞; 杨雪晶
Original assignee: 华东理工大学
Priority date: 2015-10-27
Filing date: 2016-01-11
Publication date: 2017-05-04
Also published as: CN105170630A; CN105170630B

Abstract

Provided are a combined soil washing desorption method and device. The method is as follows: polluted soil is sprayed and sieved with a wet multistage vibrating sieve (3) to remove large particles of stones or coarse sand that can be directly backfilled; washing desorption treatment is carried out on a fine soil particle suspension, and same is subjected to cyclones (10-1,10-2,10-3) connected in series and respectively equipped with solid-liquid mixers (8-1,8-2) and a micro rotational flow sequencer (9-1) in order to achieve the separation of clay pollutants of small particle size; washing desorption treatment and cyclone separation are carried out on the remaining sandy soil of intermediate particle size, wherein the recycling of a washing liquid is achieved by a precision filter (12-1); and washing treatment using clear water and cyclone separation are carried out on the soil after filtration, and finally, after dehydration through a centrifugal machine (13), the deep separation of waste water and soil particles is finally achieved, thus achieving the purposes of backfilling soil, recycling tap water and recycling a washing agent. The device parameters can be adjusted and optimized according to actual conditions, thereby effectively removing pollutants containing heavy metals, pesticides, etc., and overcoming the deficiency that current soil washing cannot be industrialized.

Description

Method and device for combined soil washing and desorption

Technical field

The invention relates to a method and a device for swirling, ultrasonic and detergent combined soil washing and desorption, belonging to the field of ectopic repair of contaminated soil.

Background technique

Soil is an important part of the ecological environment and the basis for people's survival. The deterioration of the soil environment is caused by many reasons, such as: the use of a large number of chemical fertilizers and pesticides in agriculture; the discharge of industrial waste water in the industry, the landfill of solid waste; and the landfill of daily garbage. The contaminated soil will form a secondary pollution to water resources, and will be enriched into the human body through the soil-plant system or the soil-plant-animal system food chain, which directly endangers human health. Soil pollution has the characteristics of concealment, irreversibility and long-term, and the severity of the impact. Therefore, the solution of soil pollution has always been an international difficult and hot issue.

At present, soil remediation methods at home and abroad mainly include physical repair methods, chemical repair methods and bioremediation methods, but there are disadvantages such as high cost, incompleteness, long cycle, and large environmental conditions. Soil leaching repair technology is a fast and efficient chemical leaching technology, and one of the EPA recommended soil remediation methods at the end of the 20th century.

With the application of technology and research, it is found that the amount of pollutants is closely related to the particle size distribution of the soil. Whether it is organic matter adsorbed to the soil or heavy metals that are in contact with the surface functional groups of the soil, the pollutants are mainly attached or adsorbed to the particle size. Small soil, large particle size range of 2 ~ 4mm, low pollution degree, between 2 ~ 0.076mm intermediate particle size soil particles most, belonging to sandy soil, high pollution concentration, suitable for cleaning, high concentration of clay pollution less than 0.076mm However, the washing effect is poor and needs to be treated in other ways. Therefore, the washing and sieving of the soil and the improvement of the washing separation efficiency of the small-sized soil particles are crucial for improving the soil washing efficiency and reducing the processing cost. In the field repair in foreign countries, the separation of heavy metal fine soil particles is generally carried out by mechanical screening, hydraulic sorting, gravity sorting, flotation, magnetic separation, etc. The cyclone separation technology relies on its own simple structure, large processing capacity and low operating cost. The advantages have been more and more widely used in soil washing and restoration. The cyclone soil leaching and remediation technology adopts cyclone fractionation and leaching solution to remove pollutants from the soil, so that the soil environmental quality standard meets the corresponding planning land requirements. The ectopic soil washing method has a wide application range, and has the advantages of short repair cycle, high removal efficiency, and simple operation. However, it is necessary to develop one A method and apparatus for cyclonic separation grading suitable for soil washing.

At present, the domestic soil washing technology is still in the laboratory research stage. The focus of research is usually to select the eluent, rinsing mechanism and rinsing conditions suitable for a certain heavy metal element, and the core equipment in the soil washing and repairing system. There are no reports on the application of cyclone separation technology in soil washing applications. For example, the patent authorization publication number is CN202192081U, and the name is an experimental device for removing pollutants. These devices are only suitable for laboratory ideal conditions and cannot be directly scaled up for use in soil remediation projects. For example, the patent application publication number is CN103990644A, and the name is an in-situ fully automatic contaminated soil repairing device. The equipment has weak processing capacity and many chemical residues. Therefore, it is necessary to develop a combined rinsing and repairing method and device which is suitable for the characteristics of soil properties in China and which is compact and efficient, and consumes less washing liquid.

Summary of the invention

In view of the above problems, the present invention provides a method and apparatus for soil washing and desorption using a combination of swirling, ultrasonic, and detergent techniques, using a vibrating sieve to sort out large particle size impurities, eluent during agitation and ultrasonication. Washing and desorption under conditions, and taking full advantage of the advantages of simple cyclone separation structure, low cost and high reliability, mainly through one-stage cyclone classification, two-stage cyclone washing desorption and pre-separation, three-stage enrichment and fine separation Finally, the deep separation of wastewater and soil particles is achieved, and the purpose of soil backfilling, tap water reuse, and detergent recycling is achieved, ensuring low consumption of system detergent and tap water, compact and efficient, good economy, and no re-contamination.

The specific technical solutions are as follows:

A combined soil washing and desorption method comprises the following steps:

(1) After spraying the contaminated soil, it is sieved with a wet multi-stage vibrating sieve to remove the directly backfilled stones and coarse sand with a particle diameter of more than 3 mm to ensure the particles having a particle size of 50 μm - 3 mm entering the washing and desorption system. The mass concentration is 70% or more;

(2) washing and desorbing the fine soil particle suspension obtained in the step (1), controlling the flow rate to be 2-5 m/s, and the volume concentration of the solid-liquid mixture is 5 to 40%; The mixer is transported and mixed, and then desorbed and classified by swirl washing in the first cyclone. The function of the first cyclone is particle classification, the classification accuracy is set to 100-200 μm; the first stage cyclone overflow The solid washing liquid discharged from the outlet is deeply separated by a second cyclone equipped with a micro-swirl sequencer at the front end, and the function of the second cyclone is a separation function with a separation precision of 3 μm to ensure return of the washing liquid storage tank. The solid content of the washing liquid is less than 0.03%;

(3) The remaining sandy soil with a median diameter of 10 μm to 3 mm separated by the eluent rinsing step (2) And mixing and washing desorption by the second solid-liquid mixer, followed by cyclone desorption and concentration by the third cyclone, and the function of the third cyclone is set to contain solid liquid enrichment and soil particle contamination Deep desorption function of the object to achieve the purpose of pre-separation;

(4) Finely separating the pre-separated suspension to ensure that the washing liquid is entrained to the subsequent washing process as little as possible and can achieve the purpose of washing liquid reuse;

(5) The soil separated in step (4) enters the washing tank, is washed and desorbed, and then enters the fourth cyclone equipped with a micro-swirl sequencer for concentration, and the function of the fourth cyclone is set to enrichment. The liquid solid content is increased from 3-10% to 40-60%, and then dehydrated by a centrifuge. The removed water enters the tap water tank for reuse, and the dehydrated soil is backfilled.

The storage tank for washing and desorbing the detergent is provided with an inlet and outlet pipeline, the fresh detergent is replenished through the inlet pipeline, and the detergent is discharged from the outlet pipeline to the regeneration system or the desorption system after a certain number of cycles; the detergent outlet pipeline is provided with a precision filter, The goal is to entangle the soil particles without entrainment into the regeneration system. The washing liquid entering the regeneration system can be reused again, so as not to directly efflux and not pollute the environment.

The washing and desorption treatment is ultrasonic, stirring, and eluent mixing washing and desorption.

The washing method of the washing tank is stirring and washing with water.

The solid-liquid mixture in the solid-liquid mixer rotates, and the linear velocity of the liquid is controlled to be 2-5 m/s, which ensures the conveying function and has the particle reaction washing and desorption function.

A combined swirling soil washing and desorption device comprises the following units connected in sequence: wet multistage vibrating screen 3, mud water storage tank 4, first washing tank 5-1, first solid liquid mixer 8-1 a first hydrocyclone 10-1, a second hydrocyclone 10-2 of the first micro-swirl sequencer 9-1;

The outlets of the first hydrocyclone 10-1 and the second hydrocyclone 10-2 are both connected to the second rinse tank 5-2;

The second hydrocyclone 10-2, the detergent tank 15, and the first precision filter 12-1 are sequentially connected;

The detergent tank 15 is connected to the dosing tank 14 and the second precision filter 12-2, respectively;

The second rinsing tank 5-2, the second solid-liquid mixer 8-2, the third hydrocyclone 10-3, the second precision filter 12-2, the washing tank 6, and the second micro-swirl sorting The fourth hydrocyclone 10-4 and the centrifuge 13 of the device 9-2 are connected in sequence;

The shower device 2 is disposed above the wet multi-stage vibrating screen 3.

The above device also has a water tank 16 which is respectively associated with a shower device 2 and a water washing tank 6. The centrifuge 13 is connected.

The first rinse tank 5-1 and the second rinse tank 5-2 have an ultrasound system 11-1 and an ultrasound system 11-2, respectively.

a mud pump 7-1 is disposed between the first rinse tank 5-1 and the first solid-liquid mixer 8-1; the second rinse tank 5-2 is mixed with the second solid liquid A mud pump 7-2 is disposed between the tanks 8-2; a mud pump 7-3 is disposed between the water washing tank 6 and the second micro-swirl sequencer 9-2.

a double impeller mixer is installed on the upper ends of the first rinse tank 5-1, the second rinse tank 5-2 and the water wash tank 6; and the first rinse tank 5-1 and the second rinse tank 5-2 are respectively provided with ultrasonic vibration plates.

The first micro-swirl sequencer 9-1 is a spin sequencer connected in a spiral manner with the first hydrocyclone 10-1; the second micro-swirl sequencer 9-2 is a reverse rotation The sequencer is connected in reverse rotation with the fourth hydrocyclone 10-4.

The first solid-liquid mixer 8-1 and the second solid-liquid mixer 8-2 are axial flow mixers, every 8-12D (D refers to the nominal diameter of the pipe, that is, 8-12 times the nominal diameter of the pipe) Install one, two forward and reverse according to the flow direction.

The first solid-liquid mixer 8-1 and the second solid-liquid mixer 8-2 are K-type pipe mixers, every 8-12D (D refers to the nominal diameter of the pipe, that is, 8-12 times the nominal diameter of the pipe) ) Install one.

The detergent tank 15 is continuously replenished with fresh detergent by the dosing tank 14, and the waste liquid containing the detergent in the second precision filter 12-2 is discharged to the detergent tank 15.

The spraying device 2 has a plurality of nozzles; the wet multi-stage vibrating screen 3 is divided into two stages, the first stage screen removes stones larger than 20 mm, and the second stage screens out 3-20 mm coarse sand.

The first hydrocyclone 10-1 and the second hydrocyclone 10-2 can separate a small portion of fine particle contaminants of less than about 3 μm from the soil, enter the detergent tank 15, and enter the first rinse again. The tank 5-1 and the second rinse tank 5-2 are rinsed.

The above device can expand the processing capability by means of a parallel hydrocyclone.

The second precision filter 12-2 can be replaced with a centrifuge according to actual processing conditions.

The centrifuge 13 can be replaced with a filter press according to actual processing conditions.

The beneficial effects of the invention are:

(1) The soil is multi-classified by wet multi-stage vibrating screen and hydrocyclone, and the treatment is different, which reduces the total amount of soil washing; while stirring and ultrasonic are installed in the washing tank, the washing time is greatly shortened. Improve processing efficiency; at the end of the use of precision backwash filters to achieve deep separation of wastewater and soil particles, And achieve the purpose of recycling waste water and detergent;

(2) Using a solid-liquid mixer to change the fluid transport function of the ordinary pipeline to the existing transport function and the particle reaction washing and desorption function;

(3) Using the micro-swirl sequencer and the corresponding counter-rotating inlet and the cyclo-injection type cyclone, based on the particle sorting theory in the swirling flow field, by changing the particle distribution on the inlet section of the cyclone separator from a homogeneous mixed state to Arranging states, thereby reversing the particle separation efficiency and smoothing the particle classification efficiency;

(4) The particle size in the waste liquid is reduced by the two cyclones connected in series, and the amount of waste liquid is reduced, thereby improving the backfill rate and promoting the reduction of the detergent;

(5) For the repair of contaminated soil, the method and device have the characteristics of high degree of automation, high controllability, wide application range, compact and high efficiency, and low consumption of washing liquid.

DRAWINGS

1 is a schematic structural view of a device of Embodiment 1;

2 is a schematic diagram of a combination of a microswirl sequencer and a hydrocyclone; wherein (a) is a schematic diagram of a connection mode of a spin sequencer and a hydrocyclone, and (b) is a reverse sequencer and a hydrocyclone. Schematic diagram of the connection method of the device;

Figure 3 is a schematic diagram of the outer three views and the internal spiral structure of the reverse sequencer, as shown in (a), (b), (c), (d), respectively;

Figure 4 is a schematic diagram of the outer three views and internal spiral structure of the spin sequencer, as shown in (a), (b), (c), (d), respectively.

Symbol Description:

1 conveyor belt; 2 spray equipment; 3 wet multi-stage vibrating screen; 4 mud water storage tank;

5-1 first washing tank; 5-2 second washing tank; 6 washing tank; 7-1, 7-2, 7-3 mud pump;

8-1 first solid-liquid mixer; 8-2 second solid-liquid mixer; 9-1 first micro-swirl sequencer; 9-2 second micro-swirl sequencer; 10-1 first hydrocyclone 10-2 second hydrocyclone; 10-3 third hydrocyclone; 10-4 fourth hydrocyclone; 11-1, 11-2 ultrasound; 12-1, 12-2 Precision filter; 13 centrifuge; 14 dosing tank; 15 detergent tank; 16 tap water tank.

detailed description

Hereinafter, the present invention will be specifically described by way of examples. It is to be noted that the following examples are merely illustrative of the invention and are not to be construed as limiting the scope of the invention. Some non-essential improvements and modifications made by those skilled in the art in light of the present invention are still within the scope of the present invention.

Example 1

The inventors of the present application have found through extensive and intensive research that the most effective and inexpensive method for the treatment of contaminated soils is that the treatment is large and the treatment is difficult, and the most effective and inexpensive method is to use cyclone washing and desorption. Based on the research, the initial position of the particles at the inlet section of the cyclone has an important influence on the separation performance. For the conventional cyclone inlet section, the particles are chaotic, and the design is based on the new type of cyclone. The swirler arranged in the reverse spiral arrangement of the particles has a particle size ranging from small to large, and the concentration is from high to low, which can improve the separation efficiency; and the sequential arrangement can improve the classification efficiency. Based on the above findings, the present invention has been completed.

As shown in Fig. 1, it mainly comprises: wet multistage vibrating screen 3, mud water storage tank 4, first washing tank 5-1, second washing tank 5-2, washing tank 6, mud pump 7-1 to 7-3, the first solid-liquid mixer 8-1, the second solid-liquid mixer 8-2, the first micro-swirl sequencer 9-1, the second micro-swirl sequencer 9-2, the first to the first The four hydrocyclones 10-1 to 10-4, the ultrasound systems 11-1 and 11-2, the first precision filter 12-1, the second precision filter 12-2, the centrifuge 13, the dosing tank 14, Detergent tank 15, tap water tank 16, and the like. Among them, the micro-swirl sequencer 9-1 is a spin sorter; the micro-swirl sorter 9-2 is a reverse-sequence sorter.

The contaminated soil is continuously conveyed by the conveyor belt 1 to the upper side of the vibrating screen while being sprayed and sieved. The wet multi-stage vibrating screen 3 has a two-stage screen. The primary screen has a pore size of 20 mm for removing large stones. The secondary screen has a pore size of 3 mm for removing 3-20 mm of coarse sand, but the screen The pores can be selected according to the actual situation. The fine soil particle suspension flowing into the mud water storage tank 4 flows into the first washing tank 5-1 by gravity, is stirred and ultrasonically mixed, and is continuously added with the eluent; the mud pump 7-1 pumps the mixed liquid into the first solid in series. The liquid mixer 8-1, the first hydrocyclone 10-1, the first micro-swirl sequencer 9-1, the second hydrocyclone 10-2, the fine soil particle suspension of less than 3 μm by the second hydraulic force The overflow port of the upper end of the cyclone 10-2 is discharged into the detergent tank 15, and the detergent tank 15 is connected with the first rinse tank 5-1 and the second rinse tank 5-2 to promote the multiple circulation of the detergent. The outlet pipeline enters the regeneration system, and the indirect precision filter ensures that the soil particles are not entrained into the regeneration system and the plugging condition occurs, and the detergent tank 15 is connected to the dosing tank 14 to realize the supplement of the fresh detergent. The mixture of the lower end of the first hydrocyclone 10-1 and the second hydrocyclone 10-2 flows into the second rinse tank 5-2, and the mixing is continued by stirring and ultrasonication while continuously adding the eluent. Mud pump 7-2 will mix The second solid-liquid mixer 8-2 and the third hydrocyclone 10-3 which are sequentially connected are pumped, and the fine soil particle suspension is discharged into the second shower by the upper overflow port of the third hydrocyclone 10-3. The washing tank 5-2 is rinsed again, and the mixture of the lower end of the third hydrocyclone 10-3 flows into the second precision filter 12-2, so that the detergent enters the detergent tank to realize reuse, and realizes as little washing liquid as possible. The soil is entrained into the wash tank 6. The washing tank 6 is continuously mixed by stirring while continuously adding clean tap water. The washed mixture is passed through the mud pump 7-3 into the sequentially connected second micro-swirl sequencer 9-2 and the fourth hydrocyclone 10-4, and separated again, and the overflow mixture is discharged into the washing tank 6 again. The water is washed, the lower part is suspended into a centrifuge for dehydration, the lower part is obtained by directly backfilling the soil, and the water obtained in the upper part is returned to the tap water tank 16 for reuse. The operation of the entire set of equipment can be controlled by an automatic control cabinet.

As shown in FIG. 2, (a) is a schematic diagram of a connection mode of a spin sequencer and a hydrocyclone, and (b) is a schematic diagram of a connection mode of a reverse sequencer and a hydrocyclone.

Claims

A combined soil washing and desorption method, comprising the steps of:

(1) After spraying the contaminated soil, it is sieved with a wet multi-stage vibrating screen to remove the directly backfillable stones and coarse sand with a particle diameter of more than 3 mm to ensure the particles having a particle size of 50 μm to 3 mm entering the washing and desorption system. The mass concentration is 70% or more;

(2) washing and desorbing the fine soil particle suspension obtained in the step (1), controlling the flow rate to be 2 to 5 m/s, and the volume concentration of the solid-liquid mixture is 5 to 40%; The mixer is transported and mixed, and then desorbed and classified by swirl washing in the first cyclone. The main function of the first cyclone is particle classification, the classification accuracy is 100-200 μm; the first-stage cyclone overflow The solid washing liquid discharged from the outlet is deeply separated by a second cyclone equipped with a micro-swirl sequencer at the front end, and the function of the second cyclone is a separation function with a separation precision of 3 μm to ensure return of the washing liquid storage tank. The solid content of the washing liquid is less than 0.03%;

(3) using the eluent rinsing step (2) to remove the remaining sandy soil having an intermediate particle diameter of 10 μm to 3 mm and mixing and washing the desorption by the second solid-liquid mixer, and then passing through the third cyclone The cyclone washing is desorbed and concentrated, and the function of the third cyclone is set to deepen the desorption function of the solid liquid and the contaminants in the soil particles to achieve the purpose of pre-separation;

(4) fine separation of the pre-separated suspension;

(5) The soil separated in step (4) enters the washing tank, is washed and desorbed, and then enters the fourth cyclone equipped with a micro-swirl sequencer for concentration, and the function of the fourth cyclone is set to enrichment. The liquid solid content is increased from 3 to 10% to 40 to 60%, and then dehydrated by a centrifuge, and the removed water is returned to the tap water tank for reuse, and the dehydrated soil is backfilled.
The method of claim 1 wherein said washing and desorbing treatment is ultrasonic, agitating, eluent, mixed washing and desorption.
The method according to claim 1, wherein the washing tank washing mode is stirring, water mixing washing and desorption.
The method according to claim 1, wherein the solid-liquid mixture in the solid-liquid mixer is rotated, and the linear velocity of the liquid is controlled to 2 to 5 m/s.
A combined swirling soil washing and desorption device, comprising the following units connected in sequence:

Wet multi-stage vibrating screen (3), mud water storage tank (4), first elution tank (5-1), first solid-liquid mixer (8-1), first hydrocyclone (10-1) a second hydrocyclone (10-2) of the first micro-swirl sequencer (9-1);

The outlets of the first hydrocyclone (10-1) and the second hydrocyclone (10-2) are both connected to the second rinse tank (5-2);

The second hydrocyclone (10-2), the detergent tank (15), and the first precision filter (12-1) are sequentially connected;

The detergent tank (15) is respectively connected to the dosing tank (14) and the second precision filter (12-2);

The second rinsing tank (5-2), the second solid-liquid mixer (8-2), the third hydrocyclone (10-3), the second precision filter (12-2), and the washing tank (6) The fourth hydrocyclone (10-4) and the centrifuge (13) of the second micro-swirl sequencer (9-2) are sequentially connected;

A spraying device (2) is disposed above the wet multi-stage vibrating screen (3).
The apparatus according to claim 5, further comprising a tap water tank (16), the tap water tank (16) being connected to the shower device (2), the water washing tank (6), and the centrifuge (13), respectively.
The apparatus according to claim 5, wherein said first rinse tank (5-1) and said second rinse tank (5-2) have an ultrasound system (11-1) and an ultrasound system (11, respectively) -2).
The apparatus according to claim 5, characterized in that a mud pump (7-1) is provided between the first rinse tank (5-1) and the first solid-liquid mixer (8-1) a mud pump (7-2) is disposed between the second rinse tank (5-2) and the second solid-liquid mixer (8-2); the water wash tank (6) and the micro A mud pump (7-3) is provided between the swirl sorters (9-2).
The apparatus according to claim 5, characterized in that the upper ends of the first rinse tank (5-1), the second rinse tank (5-2) and the water wash tank (6) are equipped with a double impeller mixer And, the first rinsing tank (5-1) and the second rinsing tank (5-2) are respectively provided with ultrasonic vibration plates.
The apparatus according to claim 5, wherein said first micro-swirl sequencer (9-1) is a spin sequencer, and said first hydrocyclone (10-1) is rotated in sequence The second micro-swirl sequencer (9-2) is a reverse-sequencer that is connected in reverse to the fourth hydrocyclone (10-4).
The apparatus according to claim 5, wherein said first solid-liquid mixer (8-1) and said second solid-liquid mixer (8-2) are axial flow mixers, every 8 to 12D Install one, two forward and reverse according to the flow direction;

D refers to the nominal diameter of the pipe, which is 8-12 times the nominal diameter of the pipe.
The apparatus according to claim 5, wherein said first solid-liquid mixer (8-1) and said second solid-liquid mixer (8-2) are K-type pipe mixers every 8 to 12D. Install one;

D refers to the nominal diameter of the pipe, which is 8-12 times the nominal diameter of the pipe.