Tailing pond vertical shaft seepage drainage method based on gas drive negative pressure

Abstract

The invention discloses a tailing pond vertical shaft seepage drainage method based on gas drive negative pressure, and relates to the technical field of gas drive seepage drainage. The slotted hole pipe and the inverted filter layer are mounted; starting gas-driven negative-pressure seepage drainage; a seepage draining process and water draining; the gas drive system and the slotted hole pipe are introduced on the basis of vertical seepage drainage, vacuum negative pressure can be generated in the seepage drainage well to improve the precipitation efficiency, the adopted gas drive seepage drainage precipitation effect is good, the slotted hole pipe guarantees the stability of the water inflow, the vacuum negative pressure is gradually increased from top to bottom, and the precipitation efficiency is improved. After precipitation, the non-drainage shear strength and effective stress of slag bodies are remarkably improved, the permeability coefficient is reduced compared with that before reinforcement, the reinforcement effect is continuously improved along with increase of the depth, the reinforcement effect on a soil layer exceeding the depth of a drainage well is also remarkable, and the problems that tailings with extremely fine particles, high compressibility and poor permeability are low in drainage consolidation strength, large in difficulty and poor in permeability are effectively solved. The seepage line of the tailing pond is high, and the safety risk of the tailing dam is high.

Description

Technical Field

[0001] This invention relates to the field of gas-driven drainage technology, specifically a tailings dam vertical shaft drainage method based on gas-driven negative pressure. Background Technology

[0002] Tailings dams are sites used to store tailings or other industrial waste discharged after ore beneficiation in metal or non-metal mines. They are not only storage facilities, but also, due to their unique structure and potential risks, are considered a high-potential source of man-made debris flows. Currently, tailings dams typically consist of a tailings storage system, a tailings dam drainage system, and a tailings dam return water system. The tailings storage system stores tailings discharged during the ore beneficiation process. The tailings dam drainage system ensures effective drainage of accumulated water during the rainy season or heavy rainfall to prevent excessively high water levels from causing safety issues. The tailings dam return water system recycles water from the tailings to reduce water waste and improve efficiency. However, tailings dam leakage is a common and serious safety hazard, potentially leading to dam erosion, piping, or even dam collapse, while also polluting the surrounding soil, groundwater, and ecological environment. Currently, when tailings dams are fulfilling their storage function, the characteristics of tailings slag, such as extremely fine particles, high compressibility, and poor permeability, result in low drainage consolidation strength, high wetting line, and high safety risks for tailings dams. Summary of the Invention

[0003] This invention provides a tailings dam vertical shaft drainage method based on air-driven negative pressure, which can effectively solve the problems mentioned in the background art. Currently, when tailings dams realize their storage function, the tailings slag generally has the characteristics of extremely fine particles, high compressibility, and poor permeability, which leads to low tailings drainage consolidation strength, high tailings dam wetting line, and high tailings dam safety risks.

[0004] To achieve the above objectives, the present invention provides the following technical solution: a tailings dam vertical shaft drainage method based on gas-driven negative pressure, which has a good water reduction effect on tailings slag bodies with fine particles, high compressibility and poor permeability, and can effectively solve the problems of low consolidation strength, high difficulty and high wetting line in tailings dam drainage. Includes the following steps: Step 1: Construction and layout of drainage wells; Step 2: Install the perforated tube and the filter layer; Step 3: Start-up of air-driven negative pressure drainage; Step four: the seepage process and water discharge; Step 5: Monitoring and Continuous Optimization of Results.

[0005] According to the above technical solution, in step one, the overall structural design and construction of the drainage well are realized. The gas-driven drainage shaft adopts a double-pipe structure. The double-pipe structure composed of the outer pipe and the inner pipe ensures efficient drainage and well wall stability. In the construction of the outer pipe, the outer pipe is similar to a traditional pipe well, used for reinforcement and support. It consists of a wellhead, well wall pipe, slotted pipe and sand settling section. The top of the wellhead is welded together by a loose flange. A high-pressure air inlet and a water outlet are reserved on the flange. The high-pressure air inlet and the water outlet extend through the flange into the drainage well so that the inner pipe can be connected. The well wall pipe is made of impermeable pipe materials, including steel pipe, cast iron pipe, reinforced concrete pipe or plastic pipe. The slotted pipe is connected below the well wall pipe. Its special structure is used to directly contact the tailings layer. The sand settling section is located at the bottom of the slotted pipe and is used to settle the sand and gravel and groundwater solid particles that enter the well. In the construction of the inner pipe, the inner pipe is the core of the gas-driven drainage system. It consists of three parts: a high-pressure air inlet pipe, a water outlet pipe, and a water inlet pipe. The water outlet pipe is a solid-wall PE pipe with a diameter of 40mm, the water inlet pipe is a slotted pipe with a smaller diameter, and the high-pressure air inlet pipe is a flexible hose with a diameter of 10mm.

[0006] According to the above technical solution, in step one, when specifically arranging and installing, firstly, drill holes at the selected location in the tailings dam. The depth is determined according to the characteristics of the tailings layer, specifically based on the height of the seepage line of the tailings layer and geological exploration data. After drilling, install the outer pipe at the drilling location. First, place the well wall pipe to reinforce the borehole wall and ensure that the well wall pipe sinks vertically. Then connect the slot pipe and the settling section. The settling section needs to be buried underground to a certain depth. Finally, connect the inner tube to the outer tube via a flange. During installation, ensure that the slotted tube is wrapped with stainless steel mesh as a filter layer.

[0007] According to the above technical solution, in step two, the slotted pipe is used to expand the seepage area and prevent clogging. The slotted pipe needs to be specially set after the drainage well is installed to ensure efficient seepage when facing extremely fine tailings slag. In the specific design of the perforated pipe, the diameter of the perforated pipe is designed to be 50-100mm. 12-16 rectangular seepage channels are evenly arranged longitudinally on the outer side of the pipe wall. The width of the rectangular seepage channels is 10mm and the depth is 3.5mm. Rectangular seepage channels are used to replace the round holes in ordinary drainage pipes, directly contacting the tailings. Holes are drilled at intervals of 150-200mm, with a diameter of 8mm. The contact area per meter is 3140cm², the seepage area per meter is 1600cm², the permeability ratio is 0.51, and the seepage area is expanded to 50% of the surface area. Furthermore, ordinary filters have a small seepage area and an opening rate that cannot exceed 15%. This design adopts a rectangular seepage channel design, combined with a stainless steel mesh reverse filter layer, so that the drainage pipe can achieve efficient drainage without relying on the surrounding gravel drainage layer, and is suitable for deep foundation installation.

[0008] According to the above technical solution, in step two, when setting the filter layer, a stainless steel mesh matching the soil particle size is wrapped around the outer wall of the slotted pipe to block coarse particles in the soil outside the drainage pipe, forming a natural filter layer and expanding the influence range of the drainage pipe. The stainless steel mesh aperture design allows 80% of fine tailings to pass through smoothly, leaving 20% ​​of coarse tailings to form a filter layer around the slotted pipe. By setting this filter layer, efficient drainage can be achieved without increasing the crushed stone drainage layer around the pipe, creating conditions for installing drainage pipes in deep foundation layers.

[0009] On-site adjustments can be made based on the actual tailings particle size distribution by changing parameters such as the width (10 mm – 15 mm), depth (3.5 mm), and mesh size (0.2 mm – 0.5 mm) of the rectangular seepage channel in the slotted pipe. Engineering tests have shown that when the tailings particle size distribution is 2 μm–30 μm, the above adjustments can maintain a seepage area of ​​50% of the pipe wall area and a stable drainage efficiency.

[0010] According to the above technical solution, in step two, during the specific arrangement of the slotted pipe and the filter layer, during the installation of the drainage well, the slotted pipe needs to be wrapped with stainless steel mesh beforehand and then connected to the bottom of the well wall pipe. The slotted pipe needs to be installed vertically and the mesh layer needs to be evenly wrapped. For different tailings particle sizes, the stainless steel mesh needs to be selected with matching mesh size to ensure that the mesh size of the stainless steel mesh is compatible with the particle size of the tailings soil layer. After the arrangement is completed, the sand settling section is connected to the bottom of the trench pipe for subsequent sedimentation of gravel and solid particles from groundwater that enter the drainage well.

[0011] According to the above technical solution, step three is to realize the specific operation of gas-driven negative pressure drainage, which accelerates drainage by generating vacuum negative pressure. The gas-driven drainage system specifically includes a high-pressure air inlet pipe, a water inlet pipe, and a water outlet pipe. The water outlet pipe is responsible for transporting the water-gas mixture out of the well. The high-pressure air inlet pipe inputs high-pressure gas. The bottom of the high-pressure air inlet pipe extends into the water inlet pipe. As an important component of the gas-driven negative pressure drainage system, the high-pressure air inlet pipe generates negative pressure by inputting high-pressure gas. When starting the negative pressure, connect the air inlet end of the high-pressure air inlet pipe to the external air supply equipment. The external air supply equipment supplies air, and the high-pressure air inlet pipe inputs compressed air. When the high-pressure gas passes through the water inlet pipe, a vacuum negative pressure of up to 0.1 MPa will be generated at the bottom of the water inlet pipe. After this negative pressure is transmitted to the surrounding soil layer, it forms a vacuum seepage field within a certain range. This range expands with the increase of depth. The vacuum negative pressure increases from top to bottom, accelerating the seepage and precipitation of pore water.

[0012] According to the above technical solution, in step three, when implementing the gas-driven negative pressure drainage operation, it is necessary to control the gas pressure and flow rate to avoid slurry seepage from the ground and solidification accidents in the borehole. At the same time, for shallow weathered bedrock, the pressure should be gradually increased.

[0013] According to the above technical solution, step four mainly realizes the intake and discharge of pore water. For tailings with fine particles and poor permeability, it is discharged smoothly outside the well in the form of a water-air mixture. In the specific process of realizing drainage, under the action of vacuum negative pressure, the vacuum seepage field accelerates the seepage of pore water. The pore water is continuously drawn into the water inlet pipe and mixed with gas to form an upward-moving water-air mixture. During the discharge of the water-gas mixture, the water-gas mixture enters through the inlet pipe and is transported out of the well through the outlet pipe. The outlet pipe has a solid wall structure. Finally, the water-gas mixture is discharged into the collection and treatment facility outside the tailings dam. In addition, solid particles in the water-air mixture settle in the sedimentation section, so the sedimentation section needs to be inspected regularly to remove the accumulated sand and gravel.

[0014] According to the above technical solution, step five involves evaluating the drainage effect through monitoring data and optimizing and adjusting any deficiencies. When monitoring and evaluating the effect, specifically after seepage, the strength of the slag increases and the permeability coefficient decreases. Sensors are needed to monitor the vacuum negative pressure and the outflow rate. At the same time, instruments are used to measure the seepage volume of the tailings dam regularly and to monitor the height of the phreatic line. The effect of gas-driven negative pressure seepage is evaluated by combining multiple parameters. When implementing optimization and adjustment, the depth of the drainage well and the gas pressure are adjusted based on the characteristic that the reinforcement effect increases with depth. When signs of blockage appear, the reverse filter layer and the slotted pipe are checked in time, and the stainless steel mesh is cleaned and replaced if necessary. In addition, the high-pressure air inlet pipe and water outlet pipe need to be checked regularly.

[0015] Compared with the prior art, the beneficial effects of the present invention are as follows: 1. By introducing an air-driven system and slotted pipes on the basis of traditional vertical seepage prevention, the precipitation of pore water is accelerated by vacuum negative pressure. For tailings with extremely fine particles, high compressibility and poor permeability, the dewatering efficiency is significantly improved and the tailings dam is reinforced. This is of great practical significance for ensuring the safe storage of tailings and the stability of the dam. Compared with traditional seepage prevention technology, it has the characteristics of high seepage efficiency and strong stability. Moreover, it has a significant effect on lowering the phreatic line of the tailings dam, greatly reducing the amount of earth and rock required for the sub-dam body to achieve the same stability, saving transportation and construction costs, and resulting in significant economic benefits. At the same time, it can also quickly and effectively improve the stability of the dam body, reduce the safety risks of the tailings dam, and has significant social benefits. It has great potential for promotion and application in similar tailings dam construction projects.

[0016] 2. By using air-driven drainage, an air-driven system and slotted pipes are introduced on the basis of vertical drainage. Vacuum negative pressure can be generated in the drainage well to improve the dewatering efficiency. The air-driven drainage has a good dewatering effect. The slotted pipes ensure the stability of the water inflow. The vacuum negative pressure increases from top to bottom. After dewatering, the shear strength and effective stress of the slag body without drainage are significantly improved. The permeability coefficient is reduced compared with that before reinforcement. The reinforcement effect increases with depth. The reinforcement effect is also significant for soil layers that exceed the depth of the drainage well. It effectively solves the problems of low drainage consolidation strength, high difficulty, high phreatic line of tailings dam, and high safety risk of tailings dams with extremely fine particles, high compressibility, and poor permeability.

[0017] In summary, this gas-driven drainage technology has the advantages of significant seepage prevention effect, short construction period, reasonable treatment cost, relatively simple post-maintenance, high level of automation and safety management. Its technical level is at the leading level in the domestic industry. Moreover, through the continuous operation of gas-driven drainage, the seepage line is reduced to a safe level, which has a significant effect on reducing the seepage line. Attached Figure Description

[0018] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0019] Figure 1 This is a flowchart of the steps of the gas-driven negative pressure drainage method of the present invention; Figure 2 This is a schematic diagram of the structure of the gas-driven drainage well of the present invention; Figure 3 This is a schematic diagram of the structure of the slotted tube of the present invention; Figure 4 This is a schematic diagram of the structure of the slotted tube of the present invention wrapped with stainless steel mesh. Detailed Implementation

[0020] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0021] like Figure 1 As shown, the present invention provides a technical solution, a tailings dam vertical shaft drainage method based on gas-driven negative pressure, which has a good water reduction effect on tailings slag bodies with fine particles, high compressibility and poor permeability, and can effectively solve the problems of low consolidation strength, high difficulty and high wetting line in tailings dam drainage. Includes the following steps: Step 1: Construction and layout of drainage wells; Step 2: Install the perforated tube and the filter layer; Step 3: Start-up of air-driven negative pressure drainage; Step four: the seepage process and water discharge; Step 5: Monitoring and Continuous Optimization of Results.

[0022] like Figure 2 As shown, based on the above technical solution, in step one, the overall structural design and construction of the drainage well are realized. The gas-driven drainage shaft adopts a double-pipe structure. The double-pipe structure composed of the outer pipe and the inner pipe ensures efficient drainage and well wall stability. In the construction of the outer pipe, the outer pipe is similar to that of a traditional well, used for reinforcement and support. It consists of a wellhead, well wall pipe, slotted pipe and sand settling section. The top of the wellhead is welded together by a loose flange. A high-pressure air inlet and a water outlet are reserved on the flange. The high-pressure air inlet and water outlet extend through the flange into the drainage well so that the inner pipe can be connected. It is necessary to ensure the sealing of the wellhead to prevent gas leakage. The well wall pipe is made of impermeable pipe material, which is steel pipe. The well wall pipe has strong corrosion resistance and is mainly used to reinforce the well wall and prevent collapse. The slotted pipe is connected below the well wall pipe. Its special structure is used to directly contact the tailings layer. The sand settling section is located at the bottom of the slotted pipe and is used to settle the sand and gravel and groundwater solid particles that enter the well to prevent siltation. In the construction of the inner pipe, the inner pipe is the core of the gas-driven drainage system. It consists of three parts: a high-pressure air inlet pipe, a water outlet pipe, and a water inlet pipe. The water outlet pipe is a solid-wall PE pipe with a diameter of 40mm. The water inlet pipe uses a slotted pipe with a smaller diameter to optimize gas flow and improve efficiency. The high-pressure air inlet pipe is a flexible hose with a diameter of 10mm.

[0023] Based on the above technical solution, in step one, when specifically arranging and installing, firstly, drill holes at the selected location in the tailings dam. The depth is determined according to the characteristics of the tailings layer, specifically based on the height of the seepage line of the tailings layer and geological exploration data. After drilling, install the outer pipe at the drilling location. First, place the well wall pipe to reinforce the borehole wall and ensure that the well wall pipe sinks vertically. Then connect the slot pipe and the settling section. The settling section needs to be buried underground to a certain depth. Finally, the inner pipe, including the high-pressure air inlet pipe, water outlet pipe, and water inlet pipe, is connected to the outer pipe through a flange to ensure a tight seal. During installation, it is necessary to ensure that the grooved pipe is wrapped with stainless steel mesh as a filter layer to optimize seepage.

[0024] like Figure 3-4 As shown, based on the above technical solution, in step two, the slotted pipe is used to expand the seepage area and prevent clogging. The slotted pipe needs to be specially set after the drainage well is installed to ensure efficient seepage when facing extremely fine tailings slag. In the specific design of the perforated pipe, the diameter of the perforated pipe is designed to be 80mm. Fourteen rectangular seepage grooves are evenly arranged longitudinally on the outer side of the pipe wall. The width of the rectangular seepage groove is 10mm and the depth is 3.5mm. Rectangular seepage grooves replace the round holes in ordinary drainage pipes, directly contacting the tailings. Compared with the traditional round hole design, this increases the seepage area. Holes are drilled at 180mm intervals with a diameter of 8mm, resulting in a contact area of ​​3140cm² per meter and a seepage area of ​​1600cm² per meter, with a permeability ratio of 0.51. This expands the seepage area to 50% of the surface area. Furthermore, ordinary filters have a small seepage area. To avoid clogging due to excessive openings, the opening rate must not exceed 15%. This design adopts a rectangular seepage channel design, combined with a stainless steel mesh filter layer, so that the drainage pipe can achieve efficient drainage without relying on the surrounding gravel drainage layer, and is suitable for deep foundation installation.

[0025] Based on the above technical solution, in step two, when setting the filter layer, a stainless steel mesh matching the soil particle size is wrapped around the outer wall of the slotted pipe. The stainless steel mesh is white steel mesh, which blocks coarse particles in the soil outside the drainage pipe, forming a natural filter layer, expanding the influence range of the drainage pipe and improving the anti-clogging ability. The stainless steel mesh aperture design allows 80% of fine tailings to pass through smoothly, leaving 20% ​​of coarse tailings to form a filter layer around the slotted pipe, preventing fine particles from entering the pipe and causing blockage. By setting this filter layer, efficient drainage can be achieved without increasing the crushed stone drainage layer around the pipe, creating conditions for installing drainage pipes in deep foundation layers.

[0026] Based on the above technical solution, in step two, during the specific arrangement of the slotted pipe and the filter layer, during the installation of the drainage well, the slotted pipe needs to be pre-wrapped with stainless steel mesh and then connected to the bottom of the well wall pipe. The slotted pipe needs to be installed vertically, and it is necessary to ensure that the mesh layer is evenly wrapped to avoid gaps. For different tailings particle sizes, the stainless steel mesh needs to be selected with matching mesh size to ensure that the mesh size of the stainless steel mesh is compatible with the particle size of the tailings soil layer. After the arrangement is completed, the sand settling section is connected to the bottom of the trench pipe for subsequent sedimentation of gravel and solid particles from groundwater that enter the drainage well.

[0027] Based on the above technical solution, step three involves the specific operation of gas-driven negative pressure drainage. By generating vacuum negative pressure, drainage is accelerated, solving the problems of low consolidation strength and high difficulty in tailings dam drainage. Specifically, the gas-driven drainage system includes a high-pressure air inlet pipe, a water inlet pipe, and a water outlet pipe. The water outlet pipe is responsible for transporting the water-air mixture out of the well. The high-pressure air inlet pipe inputs high-pressure gas, and the bottom of the high-pressure air inlet pipe extends into the water inlet pipe. As an important component of the gas-driven negative pressure drainage system, the high-pressure air inlet pipe generates negative pressure by inputting high-pressure gas. When starting the negative pressure, connect the air inlet end of the high-pressure air inlet pipe to the external air supply equipment. The external air supply equipment is an air compressor. Compressed air is input through the high-pressure air inlet pipe. When the high-pressure gas passes through the water inlet pipe, a vacuum negative pressure of up to 0.1MPa will be generated at the bottom of the water inlet pipe. After this negative pressure is transmitted to the surrounding soil layer, it forms a vacuum seepage field within a certain range. This range expands with the increase of depth. The vacuum negative pressure increases from top to bottom, accelerating the seepage and precipitation of pore water.

[0028] Based on the above technical solution, in step three, when implementing the gas-driven negative pressure drainage operation, it is necessary to control the gas pressure and flow rate to avoid slurry seepage from the ground and solidification accidents in the borehole. At the same time, for shallow weathered bedrock, the pressure should be gradually increased to ensure the stability of the negative pressure.

[0029] Based on the above technical solution, step four mainly realizes the intake and discharge of pore water. For tailings with fine particles and poor permeability, the water is discharged smoothly outside the well in the form of a water-air mixture. The vacuum seepage field is formed in the vertical shaft by using air-driven negative pressure to increase from top to bottom: when high-pressure gas is injected into the bottom of the inner pipe through the air inlet pipe and the pore water is quickly drawn out, the vacuum negative pressure field diffuses into the surrounding soil in a cone shape, avoiding the channelization of a single high-pressure jet; the annular loop between the outer pipe and the inner pipe also flows the water-air mixture back to be distributed around the perimeter. With the help of multi-point pressure sensors for real-time monitoring, if a local pressure change is detected, the PLC can automatically adjust the air inlet pressure and flow rate to prevent slurry leakage on the ground or pipe solidification accidents inside the borehole.

[0030] In the specific process of realizing drainage, under the action of vacuum negative pressure, the vacuum seepage field accelerates the seepage of pore water. The pore water is continuously drawn into the water inlet pipe and mixed with gas to form an upward-moving water-air mixture, which significantly improves the drainage efficiency, especially for tailings with high compressibility and poor permeability. During the discharge of the water-gas mixture, the mixture enters through the inlet pipe and is transported out of the well through the outlet pipe. The outlet pipe has a solid wall structure to ensure stable transport and avoid leakage. Finally, the water-gas mixture is discharged into the collection and treatment facility outside the tailings dam to quickly lower the phreatic line, ensure that the phreatic line drops to a safe level, and reduce the risk to the dam. In addition, solid particles in the water-air mixture settle in the settling section to prevent clogging of the system. Therefore, the settling section needs to be inspected regularly to remove accumulated sand and gravel. A dedicated sedimentation chamber is set at the bottom of the slotted pipe. When the water-air mixture flows through this chamber, due to the sudden change in the pipe's inner diameter and the sharp drop in flow velocity, the mixture's flow velocity slows down from high speed to low speed instantly. Under the action of gravity and inertia, solid particles detach from the airflow and settle downwards, forming a stable gravel coating in the sedimentation chamber. The deposited gravel can be periodically removed through the inspection port reserved on the side wall of the sedimentation chamber, ensuring continuous and efficient drainage.

[0031] Based on the above technical solution, step five is to evaluate the drainage effect through monitoring data and optimize and adjust any deficiencies to ensure long-term stability. When monitoring and evaluating the effect, specifically after seepage, the strength of the slag increases and the permeability coefficient decreases. Sensors are needed to monitor the vacuum negative pressure and the outflow rate. At the same time, instruments are used to measure the seepage volume of the tailings dam regularly and to monitor the height of the phreatic line. The effect of gas-driven negative pressure seepage is evaluated by combining multiple parameters. When implementing optimization and adjustment, the depth of the drainage well and the gas pressure are adjusted based on the characteristic that the reinforcement effect increases with depth. When signs of blockage appear, the reverse filter layer and the slotted pipe are checked in time, and the stainless steel mesh is cleaned and replaced if necessary. In addition, the high-pressure air inlet pipe and water outlet pipe need to be checked regularly to ensure sealing. A detachable maintenance section is arranged above the sedimentation section, and a stainless steel mesh with a particle size matching the tailings is wrapped around the slotted pipe as a natural filter layer. The maintenance section is quickly connected to the main pipeline through a slip-on flange. With the help of backwash valves, the mesh and slotted pipe can be flushed and unclogged online using high-pressure gas or reverse water flow without interrupting the gas-driven negative pressure drainage operation, effectively removing blockages.

[0032] The various embodiments in this specification are described in a progressive manner, with each embodiment focusing on the differences from other embodiments. The same or similar parts between the various embodiments can be referred to each other.

[0033] This document uses specific examples to illustrate the principles and implementation methods of the present invention. The descriptions of the above embodiments are only for the purpose of helping to understand the method and core ideas of the present invention. Furthermore, those skilled in the art will recognize that, based on the ideas of the present invention, there will be changes in the specific implementation methods and application scope. Therefore, the content of this specification should not be construed as a limitation of the present invention.

Claims

1. A tailings dam vertical shaft seepage drainage method based on gas-driven negative pressure, characterized in that: It has a good water reduction effect on tailings dams with fine particles, high compressibility and poor permeability, and can effectively solve the problems of low consolidation strength, high difficulty and high wetting line in tailings dam drainage. Includes the following steps: Step 1: Construction and layout of drainage wells; Step 2: Install the perforated tube and the filter layer; Step 3: Start-up of air-driven negative pressure drainage; Step four: the seepage process and water discharge; Step 5: Monitoring and Continuous Optimization of Results.

2. The tailings dam vertical shaft seepage drainage method based on gas-driven negative pressure according to claim 1, characterized in that: Step one involves the overall structural design and construction of the drainage well. The gas-driven drainage shaft adopts a double-pipe structure, which ensures efficient drainage and well wall stability through the double-pipe structure composed of an outer pipe and an inner pipe. In the construction of the outer pipe, the outer pipe is similar to a traditional pipe well, used for reinforcement and support. It consists of a wellhead, well wall pipe, slotted pipe and sand settling section. The top of the wellhead is welded together by a loose flange. A high-pressure air inlet and a water outlet are reserved on the flange. The high-pressure air inlet and the water outlet extend through the flange into the drainage well so that the inner pipe can be connected. In the construction of the inner pipe, the inner pipe is the core of the gas-driven drainage system. It consists of three parts: a high-pressure air inlet pipe, a water outlet pipe, and a water inlet pipe. The water outlet pipe is a solid-wall PE pipe with a diameter of 40mm, the water inlet pipe is a slotted pipe with a smaller diameter, and the high-pressure air inlet pipe is a flexible hose with a diameter of 10mm.

3. The tailings dam vertical shaft seepage drainage method based on gas-driven negative pressure according to claim 2, characterized in that: In step one, when specifically arranging and installing, first drill holes at the selected location in the tailings dam. The depth is determined according to the characteristics of the tailings layer, specifically based on the height of the seepage line of the tailings layer and geological exploration data. After drilling, install the outer pipe at the drilling location. First, place the well wall pipe to reinforce the borehole wall and ensure that the well wall pipe sinks vertically. Then connect the slot pipe and the settling section. The settling section needs to be buried underground to a certain depth. Finally, connect the inner tube to the outer tube via a flange. During installation, ensure that the slotted tube is wrapped with stainless steel mesh as a filter layer.

4. The tailings dam vertical shaft seepage drainage method based on gas-driven negative pressure according to claim 2, characterized in that: In step two, the slotted pipe is used to expand the seepage area and prevent clogging. The slotted pipe needs to be specially installed after the drainage well is installed to ensure efficient seepage when facing extremely fine tailings slag. In the specific design of the perforated pipe, the diameter of the perforated pipe is designed to be 50-100mm. 12-16 rectangular seepage grooves are evenly arranged longitudinally on the outer side of the pipe wall. The width of the rectangular seepage groove is 10mm and the depth is 3.5mm. The rectangular seepage grooves replace the round holes in ordinary drainage pipes to directly contact the tailings. Holes are drilled at intervals of 150-200mm with a diameter of 8mm. The contact area per meter is 3140cm2, the seepage area per meter is 1600cm2, the permeability ratio is 0.51, and the seepage area is expanded to 50% of the surface area.

5. The tailings dam vertical shaft seepage drainage method based on gas-driven negative pressure according to claim 4, characterized in that: In step two, when setting up the filter layer, a stainless steel mesh matching the soil particle size is wrapped around the outer wall of the perforated pipe to block coarse particles in the soil from entering the drainage pipe, forming a natural filter layer and expanding the influence range of the drainage pipe.

6. The tailings dam vertical shaft seepage drainage method based on gas-driven negative pressure according to claim 4, characterized in that: In step two, during the specific arrangement of the slotted pipe and the filter layer, during the installation of the drainage well, the slotted pipe needs to be pre-wrapped with stainless steel mesh and then connected to the bottom of the well wall pipe. The slotted pipe needs to be installed vertically, and it is necessary to ensure that the mesh layer is evenly wrapped.

7. A tailings dam vertical shaft seepage drainage method based on gas-driven negative pressure according to claim 2, characterized in that: Step three involves the specific operation of gas-driven negative pressure drainage, which accelerates drainage by generating vacuum negative pressure. The gas-driven drainage system specifically includes a high-pressure air inlet pipe, a water inlet pipe, and a water outlet pipe. The water outlet pipe is responsible for transporting the water-gas mixture out of the well. The high-pressure air inlet pipe inputs high-pressure gas, and the bottom of the high-pressure air inlet pipe extends into the water inlet pipe. As an important component of the gas-driven negative pressure drainage system, the high-pressure air inlet pipe generates negative pressure by inputting high-pressure gas. When starting the negative pressure, connect the air inlet end of the high-pressure air inlet pipe to the external air supply equipment. The external air supply equipment supplies air, and the high-pressure air inlet pipe inputs compressed air. When the high-pressure gas passes through the water inlet pipe, a vacuum negative pressure of up to 0.1 MPa will be generated at the bottom of the water inlet pipe. After this negative pressure is transmitted to the surrounding soil layer, it forms a vacuum seepage field within a certain range. This range expands with the increase of depth. The vacuum negative pressure increases from top to bottom, accelerating the seepage and precipitation of pore water.

8. A tailings dam vertical shaft seepage drainage method based on gas-driven negative pressure according to claim 7, characterized in that: In step three, when implementing the gas-driven negative pressure drainage operation, it is necessary to control the gas pressure and flow rate to avoid slurry seepage from the ground and solidification accidents in the borehole. At the same time, for shallow weathered bedrock, the pressure should be gradually increased.

9. A tailings dam vertical shaft seepage removal method based on gas-driven negative pressure according to claim 7, characterized in that: Step four mainly realizes the intake and discharge of pore water. For tailings with fine particles and poor permeability, it is discharged out of the well in the form of a water-air mixture. In the specific process of realizing drainage, under the action of vacuum negative pressure, the vacuum seepage field accelerates the seepage of pore water. The pore water is continuously drawn into the water inlet pipe and mixed with gas to form an upward-moving water-air mixture. During the discharge of the water-gas mixture, the water-gas mixture enters through the inlet pipe and is transported out of the well through the outlet pipe. The outlet pipe has a solid wall structure. Finally, the water-gas mixture is discharged into the collection and treatment facility outside the tailings dam. In addition, solid particles in the water-air mixture settle in the sedimentation section, so the sedimentation section needs to be inspected regularly to remove the accumulated sand and gravel.

10. A tailings dam vertical shaft seepage removal method based on gas-driven negative pressure according to claim 1, characterized in that: Step five involves evaluating the drainage effect using monitoring data and making optimizations and adjustments to address any shortcomings. When implementing effect monitoring and evaluation, specifically after seepage, the strength of the slag increases and the permeability coefficient decreases. Sensors are needed to monitor the vacuum negative pressure and the outflow rate. At the same time, instruments are used to periodically measure the seepage volume of the tailings dam and monitor the height of the phreatic line, so as to evaluate the effect of gas-driven negative pressure seepage by combining multiple parameters.

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