A method and system for shield tunneling slurry separation and resource recycling.

Abstract

This invention provides a method and system for shield tunneling slurry separation and resource recycling. The method employs a shield tunneling slurry separation and resource recycling system to treat shield tunneling slurry. This system includes a slurry separation and grading device, a wall-breaking and mixing device with uniform distribution and deep cone thickening, and a filter press connected sequentially according to the shield tunneling slurry feeding sequence. The method includes the following steps: the shield tunneling slurry enters the slurry separation and grading device to separate coarse particles and a first slurry; the first slurry enters the wall-breaking and mixing device to break down and mix the uneven solid particles, and then enters the uniform distribution device to be uniformly and thoroughly mixed with flocculant to obtain a second slurry; the second slurry is concentrated by sedimentation in the deep cone thickening device to obtain a third slurry; the third slurry enters the filter press and is filtered to obtain slurry with a water content of less than 30%, with water reused throughout the process. The method of this invention has good separation effect and is environmentally friendly and low-carbon. The system of this invention has high production efficiency.

Description

Technical Field

[0001] This invention relates to the field of shield tunneling slurry treatment technology, specifically to a method and system for shield tunneling slurry separation and resource recycling. Background Technology

[0002] With the rapid development of my country's economy, urban traffic congestion has become increasingly severe. To effectively alleviate urban traffic pressure, subway construction has been accelerated. Shield tunneling is a crucial part of subway construction. Due to geological conditions, segment assembly quality, or other reasons, the strata need to be disturbed multiple times during shield tunneling, generating a large amount of slurry. This slurry not only contains a large amount of mud and water, but also has high viscosity, density, and hardness, and may contain certain amounts of heavy metals such as iron, nickel, and chromium. Improper handling can cause serious pollution to the surrounding land environment and water quality. Therefore, shield tunneling slurry must be treated before it can be transported off-site. Shield tunneling slurry is mainly composed of water and soil, with its main components including clay, expansive soil, water, and additives. The slurry has high fluidity and viscosity, making the separation of liquid and solid components difficult. Therefore, providing a method and system for shield tunneling slurry separation and resource recycling is of great significance.

[0003] Chinese patent application number CN201710014477.9, entitled "A Method for Harmless Treatment of Shield Tunnel Excavation Soil," discloses a method for treating shield tunnel excavation soil. This method involves: hydraulically washing the shield tunnel excavation soil through a slurry separation device to separate slurry and washed gravel particles; subjecting the slurry to a slurry treatment process to form mud-water and mud blocks; and further purifying the mud-water through a mud-water treatment system. In this patent, the gravel particles formed after treatment of the shield tunnel excavation soil can be used as concrete aggregate, turning waste into treasure and increasing economic value; the mud blocks, with their low sand and moisture content, can be used as brick-making materials, producing high-quality bricks; and the mud-water can be reused after treatment. However, this method differs from the method in this application, exhibiting poor mud-water separation, slow concentration speed, low production efficiency, and a higher moisture content in the final mud blocks. Summary of the Invention

[0004] In view of the shortcomings of the prior art, the purpose of this invention is to solve one or more problems existing in the prior art. For example, one objective of this invention is to provide a shield tunneling slurry separation and resource recycling method that achieves uniform mixing, good sedimentation separation effect, low water content of the produced slurry, and continuous output.

[0005] To achieve the above objectives, the present invention provides a method for shield tunneling slurry separation and resource recycling. This method utilizes a shield tunneling slurry separation and resource recycling system to treat shield tunneling slurry. The system includes a slurry separation and grading device, a wall-breaking and mixing device for uniform distribution and deep cone thickening, and a filter press connected sequentially according to the shield tunneling slurry feeding sequence. The wall-breaking and mixing device for uniform distribution and deep cone thickening includes a wall-breaking mixing device, a uniform distribution device, and a deep cone thickening device. The method includes the following steps: the shield tunneling slurry enters the slurry separation and grading device to separate coarse particles and a first slurry; the first slurry enters the wall-breaking mixing device to break up uneven solid particles and uniformly mix the slurry, and then enters the uniform distribution device to be uniformly and thoroughly mixed with flocculant to obtain a second slurry; the second slurry enters the deep cone thickening device for sedimentation and concentration to obtain a third slurry with a water content of 20%–40%; the third slurry enters the filter press, and after filtration, a slurry with a water content of less than 30% is obtained.

[0006] According to one or more exemplary embodiments of one aspect of the present invention, the water content of the shield tunneling slurry can be above 70%; the uneven solid particles can be formed into regular spherical particles after being broken up multiple times.

[0007] According to one or more exemplary embodiments of one aspect of the present invention, the third slurry can be pumped to the filter press by a slurry pump.

[0008] According to one or more exemplary embodiments of one aspect of the present invention, the system may further include a greywater reuse tank connected to the deep cone thickener and the filter press, and the method may further include: allowing the overflow water from the deep cone thickener and the filtrate from the filter press to flow by gravity to the greywater reuse tank.

[0009] According to one or more exemplary embodiments of one aspect of the present invention, the step of screening out coarse particles and the first slurry may include: feeding shield tunneling slurry into a rotating drum screen of a slurry separation and grading device through a feed pipe; injecting high-pressure water into the shield tunneling slurry through a high-pressure pipe, causing the shield tunneling slurry to be dispersed; adding a dispersant to the drum screen to promote slurry dispersion; screening out coarse and fine particles in the shield tunneling slurry under the action of high-pressure water, dispersant, and drum screen; conveying the coarse particles to the end of the drum screen through a spiral conveyor on the inner wall of the drum screen, discharging them as dry material into a collection box, and then outputting them through the coarse particle outlet; conveying the fine particles to the screen around the drum by centrifugal force and gravity, discharging them, and forming a first slurry with water, which enters the collection box and then flows out through the slurry outlet.

[0010] According to one or more exemplary embodiments of one aspect of the present invention, the coarse particles may be particles with a diameter greater than 1 mm, and the fine particles may be particles with a diameter less than 1 mm.

[0011] According to one or more exemplary embodiments of one aspect of the present invention, the dispersant may include inorganic nano-dispersants, environmentally friendly surfactants, and mud cleaning agents.

[0012] According to one or more exemplary embodiments of one aspect of the present invention, the step of breaking down the wall and stirring the slurry uniformly may include: a first slurry entering the tank of the wall-breaking and stirring device through the feed inlet of the tank; the uneven solid particles in the slurry being broken down first by a cutting head rotating inside the tank, and then further broken down by a shearing and stirring blade rotating at high speed inside the tank; the slurry being stirred by the shearing and stirring blade to achieve uniform solid-liquid mixing; and the slurry flowing out from the discharge outlet at the lower end of the tank.

[0013] According to one or more exemplary embodiments of one aspect of the present invention, the step of uniformly and fully mixing with flocculant and settling and concentrating in the uniform distribution device may include: the slurry flowing out of the wall-breaking agitator enters the inner well of the uniform distribution device tangentially from the feed pipe and circulates; the slurry flows out from the bottom periphery of the inner well in a uniform jet state and enters the annulus of the inner well and the outer well; flocculant is added to the annulus; the slurry and flocculant are fully and uniformly mixed to obtain a second slurry; the second slurry enters the deep cone thickener and is settled and concentrated to obtain a third slurry; the clear water generated in the settling and concentration process enters the annulus through the dilution port of the outer well and is added to the settling process to achieve cyclic settling and concentration.

[0014] Another aspect of the present invention provides a shield tunnel slurry separation and resource recycling system. The system may include a slurry separation and grading device, a wall-breaking and mixing device and a deep cone thickening device and a filter press connected in sequence according to the shield tunnel slurry feeding process, and a greywater reuse tank connected to the deep cone thickening device and the filter press. The wall-breaking and mixing device and the deep cone thickening device are designed as an integrated unit of the wall-breaking and mixing device, the uniform distribution device and the deep cone thickening device.

[0015] Compared with the prior art, the beneficial effects of the present invention include at least one of the following:

[0016] (1) The shield tunnel mud-water separation and resource recycling treatment method proposed in this invention is much more efficient than natural sedimentation separation, has a good sedimentation separation effect, and the treated mud has a low water content.

[0017] (2) The shield tunneling mud-water separation and resource recycling method proposed in this invention can screen the solid matter in the mud multiple times. Attached Figure Description

[0018] The above and other objects and features of the present invention will become clearer from the following description taken in conjunction with the accompanying drawings, in which:

[0019] Figure 1A schematic flowchart of a shield tunneling slurry separation and resource recycling method according to an exemplary embodiment of the present invention is shown. Detailed Implementation

[0020] In the following description, a shield tunneling slurry separation and resource recycling method and system of the present invention will be described in detail with reference to the accompanying drawings and exemplary embodiments.

[0021] It should be noted that terms such as "first" and "second" are merely for ease of description and distinction, and should not be interpreted as indicating or implying relative importance. Terms such as "upper," "lower," "inner," "outer," "left," "right," "middle," and "bottom" are merely for ease of description and to establish relative orientations or positional relationships, and do not indicate or imply that the component referred to must have that specific orientation or position.

[0022] In a first exemplary embodiment of the present invention, the shield tunneling slurry separation and resource recycling treatment method can employ a shield tunneling slurry separation and resource recycling treatment system to treat the shield tunneling slurry. This system may include a slurry separation and grading device, a wall-breaking and mixing device with uniform distribution and deep cone thickening device, and a filter press connected sequentially according to the shield tunneling slurry feeding sequence. The wall-breaking and mixing device with uniform distribution and deep cone thickening device includes a wall-breaking and mixing device, a uniform distribution device, and a deep cone thickening device. The integrated design of the wall-breaking and mixing device with uniform distribution and deep cone thickening reduces the equipment's footprint, facilitates construction, improves work efficiency, and increases the slurry treatment capacity.

[0023] Figure 1 A schematic flowchart of a shield tunneling slurry separation and resource recycling method according to an exemplary embodiment of the present invention is shown.

[0024] like Figure 1 As shown, the shield tunneling slurry separation and resource recycling method mainly includes the following steps: solid classification and slurry separation of the shield tunneling slurry, followed by cell wall breaking and stirring, high-efficiency thickening, high-pressure filtration, and finally, off-site transport of the resulting slurry to a stockpile. The clean water is then reused as greywater, achieving the recycling of shield tunneling slurry. During the process, the clean water from the high-efficiency thickening process can be reused as greywater, and the slurry generated during solid classification can be transported off-site to a stockpile.

[0025] In the context of shield tunneling slurry separation and resource recycling systems, the main methods for shield tunneling slurry separation and resource recycling include the following steps:

[0026] S1. The slurry from the tunnel boring machine (TBM) enters the slurry separation and grading device, where it undergoes washing, screening, and filtration to separate coarse and fine particles, outputting the first slurry. Specifically, the TBM slurry enters the drum screen of the slurry separation and grading device through the feed pipe. The drum screen rotates, and high-pressure water is simultaneously injected into the slurry through a high-pressure pipe to disperse it. A dispersant is added to the drum screen to further promote dispersion. Under the action of high-pressure water, dispersant, and multiple filter screens, the slurry is separated into coarse and fine particles. The coarse particles are conveyed to the end of the drum screen through the spiral structure on the inner wall, and discharged separately as dry material, entering the collection box from the drum screen and then exiting through the coarse particle outlet. This can then be transported off-site. The fine particles are conveyed by centrifugal force and gravity to the screens around the drum and discharged. The fine particles and water are discharged simultaneously, forming the first slurry, which enters the collection box and then flows out through the slurry outlet. Here, coarse particles can be particles with a diameter greater than 1 mm, and fine particles can be particles with a diameter less than 1 mm. Furthermore, the dispersant may include inorganic nano-dispersants, environmentally friendly surfactants, and mud cleaning agents, etc., with the dosage determined according to the specific site conditions.

[0027] S2. The first slurry enters the wall-breaking and mixing device for further refinement of solid particles. This process involves multiple rounds of wall breaking to ensure uniform mixing of the slurry. The intermediate slurry is then output into a uniform distribution device to obtain the second slurry. The second slurry enters a deep cone thickener for sedimentation and concentration, resulting in the output of the third slurry. Specifically, the first slurry enters the tank through the inlet of the wall-breaking and mixing device. Irregular solid particles in the slurry are first broken up by rotating cutting blades within the tank. These particles then flow to the bottom of the tank and are further refined by high-speed rotating shearing and mixing blades. After multiple rounds of breaking down the uneven solid particles, regular spherical particles are formed. Simultaneously, the slurry is further homogenized by the shearing and mixing blades. The intermediate slurry flows out through the outlet at the bottom of the tank. The intermediate slurry enters tangentially from the feed pipe into the inner well of the uniform distribution device for circulation (i.e., the trajectory and direction of the circulation and stirring motion of the uniform distribution device). The slurry flows out uniformly in a jet state from the discharge outlet around the bottom of the inner well, entering the annular space between the inner and outer wells. The inner and outer wells of the uniform distribution device are spaced a certain distance apart, with the inner well being higher than the outer well. Flocculant is added to this annular space, and after the slurry and flocculant are fully mixed, a second slurry is obtained. The slurry is then allowed to settle evenly to ensure uniform distribution within the deep cone thickener. In the cylinder of the deep cone thickener, sedimentation and concentration occur to form a third slurry. The clear water generated during the formation of the third slurry can enter the annular space through the dilution port at the top of the outer well to undergo another settling process, achieving cyclic sedimentation and concentration. The deep cone thickener outputs the third slurry after repeated sedimentation and concentration. Here, the slurry in the deep cone thickener undergoes sedimentation and separation under the action of flocculant and the device itself. Solid particles move downwards and settle at the bottom of the cylinder, while the clear water separated from the solid particles forms a water layer above the cylinder. When the water level in the deep cone thickener rises to the height of the dilution port at the top of the outer well, the upper water layer can flow back into the annulus through the dilution port, remixing with the slurry and added flocculant in the annulus. This dilutes and adjusts the slurry concentration to achieve the optimal sedimentation effect, while also promoting mixing between the slurry and flocculant, improving mixing efficiency and effect, and further enhancing the sedimentation and separation effect of the slurry in the deep cone thickener. Simultaneously, the upper clear water can also flow out of the deep cone thickener through the overflow port on the cylinder wall and be recycled.

[0028] S3. The third slurry enters the filter press and is filtered to obtain mud with very low water content.

[0029] S4. The mud is transported by belt to the transfer device and then transported to the stockpile.

[0030] In this exemplary embodiment, the water content of the shield slurry can be above 70%, for example 74%, 80%, or 91%. The water content of the third slurry can be between 20% and 40%, for example 21%, 34%, or 40%. The water content of the mud can be less than 30%, for example 17%, 26%, or 29%.

[0031] In this exemplary embodiment, the third slurry can be pumped from the deep cone thickener to the filter press via a slurry pump.

[0032] In this exemplary embodiment, the shield tunneling slurry separation and resource recycling treatment system may further include a greywater reuse tank, which is connected to a deep cone thickener and a filter press. The shield tunneling slurry separation and resource recycling treatment method may further include: the overflow water from the deep cone thickener and the filtrate from the filter press flowing by gravity to the greywater reuse tank to achieve water resource recycling, making the process more environmentally friendly and low-carbon.

[0033] In this exemplary embodiment, the filter press may be a plate and frame filter press, and the transfer device may be a dump truck.

[0034] In this exemplary embodiment, the cell-wall breaking and stirring device ensures stable operation while maintaining high-speed stirring. The device also enables high-speed shearing, continuous cell wall breaking, uniform mixing, and continuous output. The cutting blade in the device is a consumable part, secured with bolts for easy replacement.

[0035] In this exemplary embodiment, the main function of the uniform distribution device is to ensure that the feed slurry of the deep cone thickener is evenly distributed within the thickener, achieving the optimal settling concentration and thus obtaining the best solid-liquid separation effect. The deep cone thickener can simultaneously inject mud and add flocculants for settling. When the feed slurry concentration is high, utilizing the density difference principle, the overflow water in the deep cone thickener will automatically enter the well to dilute the feed slurry to achieve the optimal settling concentration, thereby achieving the best settling effect.

[0036] A second exemplary embodiment of the present invention provides a shield tunneling slurry separation and resource recycling system. This system can implement the shield tunneling slurry separation and resource recycling method described in the first exemplary embodiment.

[0037] The treatment system may include, from left to right, a slurry separation and grading device, a wall-breaking and mixing device with uniform distribution and a deep cone thickening device, and a filter press. The wall-breaking and mixing device with uniform distribution and a deep cone thickening device is an integrated design combining the wall-breaking mixing device, the uniform distribution device, and the deep cone thickening device. This integrated design reduces the equipment's footprint, facilitates construction, and improves work efficiency and slurry treatment capacity. The tunnel boring machine's slurry is fed into the slurry separation and grading device for resource recycling. The uniform distribution device ensures that the feed slurry to the deep cone thickening device is evenly distributed within the device, achieving optimal settling concentration. The filter press can be a plate and frame filter press.

[0038] In this exemplary embodiment, a slurry pump may be provided between the deep cone thickener and the filter press.

[0039] In this exemplary embodiment, the shield tunneling slurry separation and resource recycling system may further include a greywater reuse tank. The greywater reuse tank can be located at any available location within the system. Connecting the greywater reuse tank to the deep cone thickener and the filter press facilitates the gravity flow of the overflow water from the deep cone thickener and the filtrate from the filter press to the greywater reuse tank, thereby achieving water resource recycling.

[0040] Furthermore, the shield tunneling slurry separation and resource recycling system may also include conveyor belts and dump trucks. The processed slurry can be transported by conveyor belt to dump trucks and then transported to the stockpile.

[0041] The method / process of using the shield tunnel slurry separation and resource recycling system of the present invention includes:

[0042] The slurry from the tunnel boring machine (TBM) with a water content of over 70% enters the slurry separation and grading device through pipelines. After screening and washing in the slurry separation and grading device, particles with a diameter greater than 1 mm are screened out, while fine particles with a diameter less than 1 mm are mixed with water to form slurry which enters the wall-breaking and mixing device. After the wall-breaking and mixing device breaks down the irregular particles, they become regular spherical particles. The average slurry with a water content of 70% in the wall-breaking and mixing device is then transported to the uniform distribution device and mixed evenly and thoroughly with flocculant before being transported to the deep cone thickening device. The slurry with a water content of 70% is concentrated to a water content of about 20% to 40% in the deep cone thickening device and then pumped to the plate and frame filter press. After the slurry with a water content of 20% to 40% is filtered by the plate and frame filter press, slurry with a water content of less than 30% is obtained and transported by belt to dump trucks for transport to the stockpile.

[0043] In summary, the advantages proposed by this invention include at least one of the following:

[0044] (1) The shield tunneling mud-water separation and resource recycling treatment method proposed in this invention can ensure that the mud after solid-liquid separation treatment can be formed into blocks with a low water content, which is convenient for external transportation.

[0045] (2) The clean water separated in the shield tunnel mud-water separation and resource recycling treatment method proposed in this invention can meet the requirements of environmental protection discharge and realize resource reuse.

[0046] (3) The shield tunnel slurry separation and resource recycling system proposed in this invention has complete functions and high working efficiency;

[0047] (4) The method of the present invention can filter and separate shield tunnel slurry in a large capacity and with high efficiency, and accurately classify solids of different particle sizes. The slurry settles and thickens quickly with low water content. The integrated design of the device can make the equipment small in size and footprint, with low vibration, low noise, low failure, low energy consumption, long service life, simple structure and easy to use. The process consumes less reagents, requires less maintenance, and the reduction of slurry can reduce transportation and disposal costs. It can realize the reuse of greywater, environmental protection and low carbon, low cost, high efficiency and large capacity production. It can be widely used in the comprehensive treatment of shield tunnel slurry in urban subway construction.

[0048] Although a shield tunneling slurry separation and resource recycling method and system of the present invention has been described above in conjunction with exemplary embodiments, those skilled in the art should understand that various modifications and changes can be made to the exemplary embodiments of the present invention without departing from the spirit and scope defined by the claims.

Claims

1. A method for separating and recycling slurry from tunnel boring machine (TBM) water, characterized in that, The method employs a shield tunneling slurry separation and resource recycling system to treat the shield tunneling slurry. The system includes a slurry separation and grading device, a wall-breaking and mixing device for uniform distribution and deep cone thickening, and a filter press, connected sequentially according to the shield tunneling slurry feeding sequence. The wall-breaking and mixing device for uniform distribution and deep cone thickening includes a wall-breaking and mixing device, a uniform distribution device, and a deep cone thickening device. The method includes the following steps: The slurry from the tunnel boring machine enters the slurry separation and grading device to separate coarse particles and the first slurry. The first slurry enters the cell wall breaking and mixing device to break up the uneven solid particles and mix the slurry evenly. Then, it enters the uniform distribution device and is mixed evenly and thoroughly with the flocculant to obtain the second slurry. The uneven solid particles are broken up multiple times to form regular spherical particles. The steps of breaking down the wall and mixing the slurry evenly include: the first slurry enters the tank of the wall-breaking and mixing device through the feed inlet of the tank; the uneven solid particles in the slurry are first broken down by the rotating cutting head in the tank, and then broken down again by the high-speed rotating shearing and mixing blades in the tank; the slurry is mixed by the shearing and mixing blades to make the solid and liquid evenly mixed; the slurry flows out from the discharge port at the bottom of the tank. The second slurry enters a deep cone thickener for sedimentation and concentration to obtain a third slurry with a water content of 34% to 40%. The third slurry enters the filter press equipment, and after filter pressing, mud with a water content of less than 30% is obtained; The system also includes a greywater reuse tank, which is connected to the deep cone thickener and the filter press. The method further includes allowing the overflow water from the deep cone thickener and the filtrate from the filter press to flow by gravity into the greywater reuse tank.

2. The shield tunneling slurry separation and resource recycling method according to claim 1, characterized in that, The water content of the slurry used in the tunnel boring machine is above 70%.

3. The shield tunneling slurry separation and resource recycling method according to claim 1, characterized in that, The third slurry is pumped to the filter press via a slurry pump.

4. The shield tunneling slurry separation and resource recycling method according to claim 1, characterized in that, The step of screening out coarse particles and the first slurry includes: The slurry from the tunnel boring machine is fed into the rotating drum screen of the slurry separation and grading device through the feed pipe. High-pressure water is injected into the shield tunnel slurry through a high-pressure pipe, and the shield slurry is dispersed. Add a dispersant to the drum screen to promote slurry dispersion; The slurry from the tunnel boring machine is separated into coarse and fine particles by the action of high-pressure water, dispersant and drum screen; Coarse particles are conveyed to the end of the drum screen by a spiral conveyor on the inner wall of the drum screen, discharged as dry material into the collection box, and then output through the coarse particle outlet. Fine particles are conveyed to the screen around the drum by centrifugal force and gravity and discharged. The fine particles and water form the first slurry, which enters the collection box and then flows out through the slurry outlet.

5. The shield tunneling slurry separation and resource recycling method according to claim 4, characterized in that, The coarse particles are particles with a diameter greater than 1 mm, and the fine particles are particles with a diameter less than 1 mm.

6. The shield tunneling slurry separation and resource recycling method according to claim 4, characterized in that, The dispersant includes inorganic nano-dispersants, environmentally friendly surfactants, and mud cleaning agents.

7. The shield tunneling slurry separation and resource recycling method according to claim 1, characterized in that, The steps of uniformly and thoroughly mixing the flocculant in the uniformly distributed fabric device and then settling and concentrating it include: The slurry flowing out of the wall-breaking and mixing device enters the inner well of the uniform material distribution device tangentially from the feed pipe for circulation. The slurry flows out uniformly from the discharge outlet around the bottom of the inner well and enters the annulus of the inner and outer wells; Add flocculant into the surrounding air; The second slurry is obtained after the slurry and flocculant are thoroughly and evenly mixed. The second slurry enters the deep cone thickener for sedimentation and concentration to obtain the third slurry. The clear water produced during sedimentation and concentration enters the annulus through the external well dilution port and is added to the sedimentation process to achieve cyclic sedimentation and concentration.

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