Power stirring device for fine-grained soil

Abstract

The utility model discloses a fine-grained soil power stirring device. The stirring device comprises a stirring kettle with an inner cavity and further comprises a concentric type double-shaft pored stirring paddle arranged in the center of the stirring kettle, a stirring rod of the double-shaft pored stirring paddle is of a hollow structure, and a side hole and a bottom hole are formed in the side portion and the bottom portion of the stirring rod respectively; the monitoring unit comprises a particle concentration probe and a conductivity probe which are arranged on the side wall of the stirring kettle; the collecting unit comprises a conduit, a valve and a collecting box, two ends of the conduit are respectively connected with the stirring kettle and the collecting box, and the valve is arranged at one end, close to the stirring kettle, of the conduit; the stirring device is used for leaching remediation of polluted fine-grained soil. According to the utility model, the mixing efficiency and uniformity are improved, the stirring process can be monitored in real time, leacheate is recycled, the device is simple in structure and convenient to operate, the leaching method is economical and efficient, and the device has better practicability, innovativeness, industrial application and popularization effects and sustainable development capability.

Description

Technical Field

[0001] This utility model relates to the field of environmental protection, particularly the field of soil remediation technology, and specifically to a fine-grained soil dynamic mixing device. Background Technology

[0002] Soil pollution has become a global environmental problem. Exploring efficient, environmentally friendly, and economical soil remediation technologies is crucial for improving soil quality, restoring ecological balance, and promoting sustainable development. Soil leaching technology is suitable for various types of soil pollution, including soil contaminated with organic matter, heavy metals, and pesticides, and can remove pollutants in a controllable, efficient, and economical manner, thus possessing broad application prospects. Ex-situ leaching has lower requirements for soil particle size and permeability, removes pollutants more thoroughly, is more effective at removing specific pollutants, allows for more precise monitoring during the leaching process, and reduces the secondary pollution problems associated with the use of chemical agents.

[0003] Traditional soil leaching remediation techniques suffer from limitations due to high clay content in the soil, resulting in poor flowability of the leaching solution and difficulty in fully contacting and cleaning soil particles. To address this issue, one approach is to optimize the leaching agent formulation or use solubilizers. Another approach is to employ enhanced leaching technologies, primarily ultrasonic leaching, electrodynamic field leaching, and agitated leaching, to improve the soil agglomeration caused by soil accumulation during static column leaching. Agitation leaching offers advantages such as simple equipment and low cost. It uses mechanical force to thoroughly mix and react soil particles suspended in the leaching solution, increasing the contact efficiency between the soil and the leaching solution and effectively improving the chemical leaching removal rate.

[0004] In stirred washing technology, material stirring efficiency and material mixing uniformity are among the most important performance indicators. In particular, soil at the bottom of the stirred tank tends to settle during stirring, resulting in insufficient mixing of the bottom soil and making it difficult for it to participate in the stirring washing process.

[0005] Currently, the newly disclosed blades can improve the mixing efficiency of materials in the upper and lower layers to some extent, but they still have the following shortcomings:

[0006] (1) The material mixing is still not sufficient, and the stirring area near the vessel wall is not ideal;

[0007] (2) The mixing effect of materials needs to be further improved.

[0008] Therefore, there is an urgent need to develop efficient and energy-saving fine-grained soil mixing devices and rinsing methods, which can improve the removal rate of pollutants while significantly reducing the amount of chemical agents used and lowering costs. Utility Model Content

[0009] To address the shortcomings of existing technologies, this utility model provides a dynamic mixing device for fine-grained soil.

[0010] The technical solution of this utility model is as follows:

[0011] The stirring device includes:

[0012] A stirred tank with an internal cavity;

[0013] The stirring unit includes a dual-shaft perforated stirring paddle located inside and in the center of the stirring vessel;

[0014] The monitoring unit includes a particle concentration probe and a conductivity probe, both of which are installed on the side wall of the stirred tank.

[0015] The collection unit includes a conduit, a valve, and a collection tank. The two ends of the conduit are connected to the stirring vessel and the collection tank, respectively, so that the liquid in the stirring vessel flows through the conduit to the collection tank. The valve is arranged at the port of the conduit near the stirring vessel.

[0016] The dual-axis perforated stirring impeller includes an outer impeller, an inner impeller, a stirring rod, side holes, and a bottom hole. The lower middle part of the stirring rod has a cavity, and multiple radial side holes are formed on the side of the stirring rod. These side holes are arranged at intervals along the circumference of the stirring rod, and the centers of all the side holes are located on the same radial plane. The radial plane is located below and close to the connection between the stirring rod and the outer impeller. An axial bottom hole is formed on the end face of the bottom of the stirring rod. Both the side holes and the bottom hole communicate with the cavity inside the stirring rod. An outer impeller and an inner impeller are mounted on the stirring rod. The outer impeller is coaxially arranged outside the inner impeller, and the inner impeller is located at the bottom of the stirring vessel.

[0017] The side hole is elliptical in shape, with its major axis arranged along the axial direction of the stirring rod.

[0018] The inner propeller is a single-layer propeller, and the blade angle of the inner propeller is 30° to 60°.

[0019] The outer propeller can be a frame-type propeller, such as a square frame propeller, a round frame propeller, or a diamond frame propeller.

[0020] Preferably, the inner impeller is fitted onto the bottom of the stirring rod, and the bottom end of the stirring rod extends from the center of the inner impeller to form an extension. The extension is a frustum-shaped part that is narrower at the top and wider at the bottom, and a through hole is formed along the axial direction on the bottom end face of the extension to form a bottom hole.

[0021] Furthermore, the stirring unit also includes a torque sensor, a controller, and a stirring motor. The torque sensor is used to record the torque of the dual-shaft perforated stirring paddle in real time; specifically, the stirring power is obtained from the torque of the dual-shaft perforated stirring paddle. The controller is used to control the stirring motor to turn on or off. The output shaft of the stirring motor drives the stirring rod of the dual-shaft perforated stirring paddle to rotate coaxially and synchronously with the output shaft of the stirring motor via a stirring clamp.

[0022] The monitoring unit includes several particle concentration probes and one conductivity probe. All particle concentration probes are arranged sequentially from top to bottom along the axial direction of the stirred tank on its sidewall, for measuring the solid phase concentration at different axial heights within the stirred tank. The conductivity probe is located on the bottom sidewall of the stirred tank. The monitoring unit also includes a particle concentration monitor and a conductivity monitor. The particle concentration probes are electrically connected to the particle concentration monitor and transmit the collected signals to it. Similarly, the conductivity probe is electrically connected to the conductivity monitor and transmits the collected signals to it.

[0023] The mixing vessel is equipped with a sand cushion layer, which is laid at the bottom of the mixing vessel.

[0024] The bottom of the mixing vessel is provided with a water outlet, which is connected to the interior of the mixing vessel and is also connected to a collection box via a conduit; the height of the water outlet is greater than the height of the connection between the conduit and the collection box.

[0025] Compared with the prior art, the present invention has the following beneficial technical effects:

[0026] 1. The stirring device in this utility model increases the stirring range of the material by setting a dual-shaft stirring paddle, which drives the material on the inner wall of the stirring vessel to mix, thereby improving the overall mixing efficiency of the material in the radial direction of the stirring paddle and reducing the stirring time, making it quite practical.

[0027] 2. The stirring device in this invention creates a new dynamic circulation within and outside the straight-axis impeller by opening holes in the stirring rod of the dual-shaft stirring paddle. As the material circulates up and down within the mixing vessel, it enters the hollow side holes of the stirring rod, resulting in more uniform mixing due to compression. Furthermore, since the fluid velocity in the pipe is inversely proportional to the pipe's cross-sectional area, the material movement rate within the stirring rod is increased. When it exits through the bottom hole, it impacts the material deposited at the bottom of the mixing vessel, drawing it into the mixing zone, thus innovatively achieving highly efficient mixing of the upper and lower layers of material.

[0028] 3. The stirring device in this utility model, by setting up a conductivity monitor, monitors the conductivity of the solution in real time, better controls the rinsing time during the stirring and rinsing process, optimizes the amount of rinsing solution added before and after rinsing, reduces costs more accurately and reasonably, and can stop in time when abnormal situations occur, take measures to avoid accidents, and ensure the safety of the rinsing process.

[0029] 4. The stirring device in this utility model, by setting up a particle concentration monitor, monitors the changes in particle concentration in the solution in real time, helping operators to more accurately understand the uniformity and mixing efficiency of stirring and mixing, and accurately understand the particle concentration obtained after leaching. It provides feedback for test parameters such as particle size distribution of secondary feed soil and solid-liquid ratio of soil to leaching liquid, solves the sustainable problem of multiple batches of stirring and leaching of fine-grained soil, and can be applied to the field more persistently and effectively. Attached Figure Description

[0030] Figure 1 This is a schematic diagram of the structure of the dynamic mixing device for medium and fine-grained soil according to this utility model;

[0031] Figure 2 This is a schematic diagram of the flow field in the inner cross-section of the stirred tank in this utility model;

[0032] Figure 3 This is a top view of the dual-shaft perforated stirring paddle of this utility model;

[0033] Figure 4 This is a schematic diagram of the opening of the stirring rod of the dual-shaft perforated stirring paddle in this utility model.

[0034] The components include: 1. Controller; 2. Torque sensor; 3. Stirring motor; 4. Stirring fixture; 5. Dual-shaft perforated stirring paddle; 5-1. Outer paddle; 5-2. Inner paddle; 5-3. Stirring rod; 5-4. Side hole; 5-5. Bottom hole; 6. Stirring vessel; 7. Sand cushion layer; 8. Particle concentration probe; 9. Conductivity probe; 10. Particle concentration monitor; 11. Conductivity monitor; 12. Conduit; 13. Valve; 14. Collection box. Detailed Implementation

[0035] To more clearly illustrate the technical solutions of this utility model, the present utility model will be further described below in conjunction with the accompanying drawings. Obviously, the drawings described below are only some embodiments of this utility model. For those skilled in the art, other drawings can be obtained based on these drawings without any creative effort.

[0036] The specific contents of this utility model are as follows:

[0037] The dual-shaft perforated stirring paddle in this invention improves the radial material mixing efficiency of the stirring paddle blades in the mixing vessel, allowing materials far from the stirring rod to also receive high stirring power. By setting the stirring rod to be hollow and having side holes, a material circulation is formed inside the stirring rod, and the material sprayed from the bottom hole mixes with the bottom sediment, improving the mixing efficiency of the upper and lower layers of materials. It is a relatively convenient and advanced stirring device.

[0038] The fine-grained soil leaching method using this invention employs the aforementioned high-efficiency stirring device for leaching, and uses a conductivity monitor to monitor the soil-leaching solution mixture in real time to characterize the ion concentration in the solution and determine the completion of the stirring process. A particle concentration monitor is installed to measure the concentration and particle size distribution of suspended particles in the liquid, and to assess the uniformity of mixing between the upper and lower layers of materials in the stirring vessel. A controllable leaching solution outlet is provided, allowing it to be reused as secondary leaching solution. This method possesses good practicality, innovation, industrial applicability, and sustainable development capabilities.

[0039] like Figure 1 As shown, the stirring device in this invention can be used for the leaching and remediation of solid waste pollutants, especially fine-grained soil contaminated by chemicals.

[0040] This mixing device includes a mixing vessel 6 with an internal cavity. A sand cushion layer 7 is arranged inside the mixing vessel 6, and the sand cushion layer 7 is evenly spread at the bottom of the mixing vessel 6.

[0041] In practice, the mixing vessel 6 is cylindrical in shape, with support legs installed at the bottom. The height of the support frame is adjustable, and a water outlet is provided at the bottom of the mixing vessel 6. A sand cushion layer 7 is evenly laid at the bottom of the mixing vessel 6, and the particle size of the sand cushion layer 7 is larger than the diameter of the water outlet at the bottom of the mixing vessel 6. Permeable stones are laid on top of the sand cushion layer 7.

[0042] This stirring device includes a stirring unit, including a biaxial perforated stirring paddle 5 located in the center of the stirring vessel 6.

[0043] The dual-shaft perforated stirring paddle 5 includes an outer paddle 5-1, an inner paddle 5-2, a stirring rod 5-3, side holes 5-4, and a bottom hole 5-5. The lower middle part of the stirring rod 5-3 has a cavity inside. Multiple radial side holes 5-4 are opened on the side of the stirring rod 5-3. The multiple side holes 5-4 are arranged at intervals along the circumference of the stirring rod 5-3, and the centers of all the side holes 5-4 are located on the same radial plane. The radial plane is located below the connection between the stirring rod 5-3 and the outer paddle 5-1, and is arranged close to the connection. An axial bottom hole 5-5 is opened on the end face of the bottom of the stirring rod 5-3. Both the side holes 5-4 and the bottom hole 5-5 are connected to the cavity inside the stirring rod 5-3. The outer paddle 5-1 and the inner paddle 5-2 are installed on the stirring rod 5-3. The outer paddle 5-1 is coaxially arranged outside the inner paddle 5-2, and the inner paddle 5-2 is located at the bottom of the stirring vessel 6.

[0044] Furthermore, the inner impeller 5-2 is fitted onto the bottom of the stirring rod 5-3. The bottom end of the stirring rod 5-3 extends from the center of the inner impeller 5-2 to form an extension. The extension is a frustum-shaped part that is narrow at the top and wide at the bottom. A trumpet-shaped through hole that is narrow at the top and wide at the bottom is opened along the axial direction on the bottom end face of the extension to form a bottom hole 5-5.

[0045] Specifically, the inner impeller 5-2 and the stirring rod 5-3 are detachably fixed together by screws or other components.

[0046] Specifically, the outer diameter of the outer impeller 5-1 is preferably 70% to 80% of the inner diameter of the stirred tank 6.

[0047] As an optional embodiment of this utility model, the inner propeller 5-2 is a single-layer four-bladed cross propeller with a blade angle of 30° to 60°.

[0048] As an optional embodiment of this utility model, the stirring unit further includes a controller 1, a torque sensor 2, a stirring motor 3, and a stirring clamp 4. The stirring clamp 4 is positioned above the dual-shaft perforated stirring paddle 5. The height of the stirring clamp 4 can be adjusted using a height-adjustable column-type support (such as an aluminum profile frame or a steel gantry frame), which is fixed to the equipment platform or the ground. The stirring motor 3 is mounted on the top of the stirring clamp 4. The torque sensor 2 is installed on the output shaft of the stirring motor 3, measuring the torque applied to the output shaft and converting it into an electrical signal output, which is then collected and processed by the system. The torque sensor 2 is used to record the torque of the dual-shaft perforated stirring paddle 5 in real time. In specific implementations, the stirring power is obtained from the torque of the dual-shaft perforated stirring paddle 5. The upper and lower ends of the stirring clamp 4 are fixedly connected to the output shaft of the stirring motor 3 and the stirring rod 5-3, respectively. Both the stirring motor 3 and the torque sensor 2 are electrically connected to the controller 1. The controller 1 is used to control the turning on or off of the stirring motor 3. The stirring motor 3 drives the outer impeller 5-1 and inner impeller 5-2 of the dual-shaft perforated stirring paddle 5 to rotate in the same direction, with each providing a speed greater than 10 rpm. In this embodiment, the outer impeller 5-1 and inner impeller 5-2 are mounted on the stirring rod 5-3 as follows: the outer impeller 5-1 is mainly composed of an outer impeller plate and a hollow outer stirring shaft. The hollow outer stirring shaft is coaxially sleeved on the outside of the solid section at the top of the stirring rod 5-3 (i.e., the area of ​​the stirring rod 5-3 without a cavity). The hollow outer stirring shaft is fixedly connected to the stirring rod 5-3 by welding, key connection, or bolt connection, so that the stirring motor 3 can drive the outer impeller 5-1 and inner impeller 5-2 of the dual-shaft perforated stirring paddle 5 to rotate in the same direction.

[0049] Furthermore, in the above optional embodiments, the stirring clamp 4 can have a built-in transmission device, and the hollow outer stirring shaft and the stirring rod 5-3 are connected by a bearing (rolling / sliding) or a collar (shroud) or other connecting component, so that the stirring motor 3 can drive the outer impeller 5-1 and the inner impeller 5-2 respectively. The connecting component is located within the radial gap between the hollow outer stirring shaft and the stirring rod 5-3, and the position of the connecting component corresponds to the connection between the stirring rod 5-3 and the outer impeller 5-1.

[0050] As another optional embodiment of this utility model, the stirring unit further includes a controller 1, a torque sensor 2, a first variable frequency speed control motor, and a second variable frequency speed control motor. The first and second variable frequency speed control motors are used to drive and control the speed and direction of the outer propeller 5-1 and the inner propeller 5-2, respectively. Both the first and second variable frequency speed control motors are electrically connected to the controller 1. Each of the two variable frequency speed control motors has a torque sensor 2 installed on its output shaft, and both torque sensors 2 are electrically connected to the controller 1. The AC frequency output by the frequency converter affects the motor speed, thereby controlling the speed and direction of the inner propeller 5-2 and the outer propeller 5-1, respectively, to achieve opposite rotation, same rotation, or independent rotation of the outer propeller 5-1 and the inner propeller 5-2. In this embodiment, the method of installing an outer impeller 5-1 and an inner impeller 5-2 on the stirring rod 5-3 can be as follows: The outer impeller 5-1 mainly consists of an outer impeller plate and a hollow outer stirring shaft. The hollow outer stirring shaft is coaxially sleeved on the outside of the solid section at the top of the stirring rod 5-3 (i.e., the area of ​​the stirring rod 5-3 without a cavity). The hollow outer stirring shaft and the stirring rod 5-3 are connected by a bearing (rolling / sliding) or a collar (shroud) or other connecting parts. The connecting parts are located within the radial gap between the hollow outer stirring shaft and the stirring rod 5-3, and their positions correspond to the connection point between the stirring rod 5-3 and the outer impeller 5-1. A first variable frequency speed control motor is arranged on one side of the top of the dual-shaft perforated stirring impeller 5. The output shaft of the first variable frequency speed control motor transmits power to the hollow outer stirring shaft through a transmission device (such as a gear or chain). A second variable frequency speed control motor is arranged above the dual-shaft perforated stirring impeller 5. The output shaft of the second variable frequency speed control motor transmits power to the stirring rod 5-3 through a transmission device (such as a gear or chain).

[0051] In the above implementation scheme, the first variable frequency speed control motor and the second variable frequency speed control motor can further adjust their respective heights through structures such as height-adjustable column-type supports (such as aluminum profile frames or steel gantry frames).

[0052] Optionally, the speed ratio of the inner propeller 5-2 to the outer propeller 5-1 is 1:1 to 5:1.

[0053] During the mixing process, the side holes 5-4 and bottom holes 5-5 of the stirring rod 5-3 of the dual-shaft perforated impeller 5 create a new kinematic circulation inside and outside the straight-shaft impeller blades. This kinematic circulation is as follows: Figure 2As shown, when the material circulates up and down in the stirred tank, it enters the hollow stirring rod side hole 5-4. After the material fluid enters the narrower pipe, the mixing is more uniform. According to the combined effect of the continuity equation, Bernoulli's law and frictional resistance, the movement speed of the material in the stirring rod is increased when passing through the narrower pipe. When the material rushes out from the bottom hole 5-5, it can impact the material deposited at the bottom of the stirred tank and drive it into the material mixing area, thereby achieving efficient mixing of the upper and lower layers of material.

[0054] This stirring device includes a monitoring unit comprising a particle concentration probe 8 and a conductivity probe 9 arranged on the side wall of the stirred vessel 6. The particle concentration probe 8 is used to measure the solid phase concentration at different axial heights within the stirred vessel. The monitoring unit includes several particle concentration probes 8 and one conductivity probe 9; the particle concentration probes 8 are arranged sequentially from top to bottom along the axial direction on the side wall of the stirred vessel 6 at intervals. The conductivity probe 9 is located at the bottom of the side wall of the stirred vessel 6.

[0055] The monitoring unit also includes a particle concentration monitor 10 and a conductivity monitor 11. Several particle concentration probes 8 are electrically connected to the particle concentration monitor 10 and transmit the collected signals to the particle concentration monitor 10. The conductivity probes 9 are electrically connected to the conductivity monitor 11 and transmit the collected signals to the conductivity monitor 11.

[0056] Optionally, the particle concentration probe 8 is embedded in the side wall of the stirred tank 6 via its own threads, and the particle concentration probe 8 does not contact the outer impeller 5-1 when the biaxially perforated stirring paddle 5 rotates. Optionally, the conductivity probe 9 is embedded in the side wall of the stirred tank 6 via its own threads, and the conductivity probe 9 does not contact the outer impeller 5-1 when the biaxially perforated stirring paddle 5 rotates.

[0057] In practical implementation, the placement of the conductivity monitoring instrument's probe in the solution affects the monitoring results. Therefore, the probe should be positioned as close as possible to the substance to be measured in the solution and kept stable. In this invention, the probe is placed at the bottom of the stirred tank 6. After the stirring flow field stabilizes and the various substances in the solution are evenly distributed, the solution is monitored. The particle concentration monitor measures the solid phase concentration by acquiring the intensity of reflected light when the material flows past the fiber optic probe. During the measurement process, the probe of the particle concentration monitor emits visible light of a certain intensity. When the visible light encounters the particles, it is reflected and received by the sensor installed on the probe head, converting it into a voltage signal. Subsequently, based on the relationship between the voltage value and the volume fraction of the solid phase, the particle concentration monitor can measure the solid phase concentration.

[0058] This stirring device includes a collection unit, comprising a conduit 12, a valve 13, and a collection tank 14. The two ends of the conduit 12 are connected to the stirring vessel 6 and the collection tank 14, respectively. The valve 13 is located at the end of the conduit 12 near the stirring vessel 6. When the valve 13 is opened, the liquid in the stirring vessel 6 flows through the conduit 12 into the collection tank 14.

[0059] Furthermore, the bottom of the mixing vessel 6 is provided with a water outlet, which is connected to the collection tank 14 through the conduit 12; the water head height of the water outlet is greater than the water head height at the connection between the conduit 12 and the collection tank 14.

[0060] The leaching method for contaminated fine-grained soil using this device specifically includes the following steps:

[0061] Step 1: Close valve 13 below mixing vessel 6, pour fine soil into mixing vessel 6, and then pour in the prepared rinsing solution until all particle concentration probes 10 are submerged.

[0062] Step 2: Turn on the particle concentration monitor 10 and conductivity monitor 11. After setting the working parameters of the dual-shaft perforated stirring paddle 5 through the controller 1, start the stirring motor 3. The stirring motor 3 drives the dual-shaft perforated stirring paddle 5 to stir through the stirring clamp 4. The torque sensor 2 records the torque of the dual-shaft perforated stirring paddle 5 in real time.

[0063] During the stirring process, the particle concentration monitor 10 continuously collects and monitors the particle concentration at the installation position of the conductivity probe 9. When the conductivity probe 9 at the bottom of the stirring vessel detects that the current particle concentration is higher than the threshold, the motor speed can be increased to make the particles at the bottom of the stirring vessel more evenly dispersed. When all conductivity probes 9 in the stirring vessel detect that the particle concentration exceeds the required range, the amount of rinsing liquid can be increased to ensure that the material clearing effect reaches the best state.

[0064] The conductivity monitor 11 continuously collects and monitors the conductivity of the solution in the stirred tank.

[0065] In step two, the speed of the stirring motor 3 is 100 rpm to 3000 rpm, the stirring time is 1 min to 2.0 h, and the temperature of the rinsing treatment is 20℃ to 40℃.

[0066] Step 3: Once the reading of the conductivity monitor 11 stabilizes at its minimum value, turn off the stirring motor 3 and the torque sensor 2. Then, open the valve 13 below the mixing vessel 6. The leachate is collected into the collection tank 14 through the conduit 12. After the leachate collection is complete, close the valve 13 and remove the rinsed fine soil from the mixing vessel 6. In practice, the leachate in the collection tank 14 can be used for secondary rinsing.

[0067] It should be noted that the fine soil particles mentioned in this utility model have a particle size of less than 5 mm, and the pollutants in the fine soil are heavy metals or organic pollutants.

[0068] In practice, the leaching agent is selected from one or more of deionized water or chemical leaching agents, and the choice of leaching agent is related to the type of pollutants in the fine-grained soil. For example, for fine-grained soil contaminated with heavy metals, EDTA is selected as the chemical leaching agent. In addition, the particle concentration monitor 10 can be linked with the stirring device for control, and can directly and automatically adjust the amount of leaching solution based on the monitored particle concentration signal, so as to achieve real-time and precise adjustment of the amount of leaching solution, improve the leaching effect and save water resources.

[0069] The technical solutions of the embodiments of this utility model will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of this utility model, and not all of them. Based on the embodiments of this utility model, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the protection scope of this utility model.

[0070] The specific embodiments of this utility model are as follows:

[0071] (a) Stirring device

[0072] This stirring device includes a stirring vessel 6, a stirring unit, a monitoring unit, and a collection unit.

[0073] The monitoring unit includes a particle concentration probe 8, a conductivity probe 9, a particle concentration monitor 10, and a conductivity monitor 11. The particle concentration probes 8 are embedded in the outer wall of the stirred tank 6 and arranged vertically. In this embodiment, four particle concentration probes 8 are provided. The particle concentration probes 8 are electrically connected to the particle concentration monitor 10. The conductivity probes 9 are embedded in the outer wall of the stirred tank 6, arranged vertically directly below the particle concentration probes 8, and are electrically connected to the conductivity monitor 11.

[0074] The collection unit includes a conduit 12, a valve 13, and a collection box 14. The valve 13 is installed in the extension section of the conduit 12 at the bottom of the main body of the stirred tank 6, and the collection box 14 is connected to the bottom of the main body of the stirred tank 6 through the conduit 12.

[0075] The mixing unit includes a controller 1, a torque sensor 2, a mixing motor 3, a mixing fixture 4, a dual-shaft perforated mixing paddle 5, and a sand pad 7. The controller 1 is electrically connected to the torque sensor 2 and the mixing motor 3. The mixing motor 3 is fixed to the top of the mixing fixture 4. The dual-shaft perforated mixing paddle 5 is vertically connected to the mixing fixture 4 after being tightened with screws. A sand pad 7 is provided inside the mixing vessel 6.

[0076] Specifically, the dual-shaft perforated impeller 5 includes an outer impeller 5-1, an inner impeller 5-2, an agitator 5-3, side holes 5-4, and a bottom hole 5-5. The agitator 5-3 of the dual-shaft perforated impeller 5 is hollow, the bottom hole 5-5 is located at the bottom of the agitator 5-3, and several side holes 5-4 are provided. The agitator motor 3 drives the outer impeller 5-1 and the inner impeller 5-2 of the dual-shaft perforated impeller 5 to rotate clockwise or counterclockwise, respectively, providing a speed greater than 10 rpm.

[0077] In this embodiment, the inner propeller 5-2 is a single-layer four-bladed cross propeller, and the blade angle of the inner propeller 5-2 is 45°.

[0078] like Figure 3 As shown, in this embodiment, the inner paddle 5-2 is fitted onto the bottom of the stirring rod 5-3. The bottom end of the stirring rod 5-3 extends from the center of the inner paddle 5-2, and the shape of the extended part is set as a frustum shape that is narrow at the top and wide at the bottom. A through hole is opened on the end face of the bottom end of the extended part of the stirring rod 5-3 along the axial direction to form a bottom hole 5-5 that communicates with the inside of the stirring rod 5-3.

[0079] In this embodiment, the mixing vessel 6 is cylindrical in shape, with support legs installed at the bottom. The height of the support frame is adjustable, and a water outlet is provided at the bottom of the mixing vessel 6. A sand cushion layer 7 is evenly laid at the bottom of the mixing vessel 6, and the particle size of the sand cushion layer 7 is larger than the diameter of the water outlet at the bottom of the mixing vessel 6. Permeable stones are laid on top of the sand cushion layer 7.

[0080] In this embodiment, the particle concentration probe 8 is embedded in the side wall of the stirred tank 6 via its own threads, and the particle concentration probe 8 does not contact the outer impeller 5-1 when the biaxially oriented impeller 5 rotates. The conductivity probe 9 is embedded in the side wall of the stirred tank 6 via its own threads, and the conductivity probe 9 does not contact the outer impeller 5-1 when the biaxially oriented impeller 5 rotates. The water head height at the connection between the collection tank 14 and the conduit 12 is lower than the water head height at the bottom outlet of the stirred tank 6.

[0081] The leaching method for washing contaminated fine-grained soil using the apparatus in Example 1 specifically includes the following steps:

[0082] Step 1: Adjust the height of the support legs of the mixing vessel 6, install the dual-shaft perforated stirring paddle 5 onto the stirring clamp 4, adjust the height of the stirring clamp 4 so that the dual-shaft perforated stirring paddle 5 is placed in the center of the mixing vessel 6, and the distance between the outer side of the outer paddle 5-1 and the inner bottom of the mixing vessel 6 must be greater than the outer diameter of the conductivity probe 9. Install four particle concentration probes 8 and conductivity probes 9.

[0083] Step 2: Select the appropriate chemical leaching reagent according to the type of fine soil contamination, prepare a leaching solution of a certain concentration, and weigh out a certain mass ratio of fine soil and leaching solution. Close valve 13 at the bottom of the mixing vessel 6, first pour the fine soil evenly into the bottom of the mixing vessel 6, then pour in the leaching solution until all particle concentration probes 8 are submerged.

[0084] Step 3: Turn on the particle concentration monitor 10 and conductivity monitor 11, set the stirring direction and stirring speed of the dual-shaft perforated stirring paddle 5, start the stirring motor 3 to stir, and at the same time, the torque sensor 2 records the torque of the dual-shaft perforated stirring paddle 5 in real time.

[0085] During the rinsing process, the speed of the stirring motor 3 is 100 rpm to 3000 rpm, the stirring time is 1 min to 2.0 h, and the rinsing temperature is 20℃ to 40℃.

[0086] Step 4: Stir until the reading on the conductivity monitor 11 no longer changes, indicating that all ionic pollutants in the fine-grained soil have been transferred to the solution under these conditions. Turn off the stirring motor 3 and torque sensor 2, and open the valve 13 at the bottom of the mixing vessel 6. Transfer all the leachate to the collection tank 14, considering its reuse as secondary leachate or discharge after treatment to meet standards. Close valve 13, and after solid-liquid separation, obtain the leachated soil and transfer it to a container other than the mixing vessel 6.

[0087] This specification uses specific examples to illustrate the principles and implementation methods of this utility model. The descriptions of the above embodiments are only for the purpose of helping to understand the method and core idea of ​​this utility model. At the same time, those skilled in the art will understand that, based on the idea of ​​this utility model, 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 this utility model.

Claims

1. A dynamic mixing device for fine-grained soil, characterized in that: The stirring device includes: The stirred tank (6) has an internal cavity; The stirring unit includes a biaxial perforated stirring paddle (5) located in the center of the stirring vessel (6). The monitoring unit includes a particle concentration probe (8) and a conductivity probe (9), both of which are installed on the side wall of the stirred tank (6). The collection unit includes a conduit (12), a valve (13), and a collection box (14). The two ends of the conduit (12) are connected to the stirring vessel (6) and the collection box (14) respectively. The valve (13) is located at the port of the conduit (12) near the stirring vessel (6).

2. The fine-grained soil dynamic mixing device according to claim 1, characterized in that: The dual-shaft perforated stirring impeller (5) includes an outer impeller (5-1), an inner impeller (5-2), a stirring rod (5-3), side holes (5-4), and a bottom hole (5-5). The stirring rod (5-3) has an internal cavity, and multiple radial side holes (5-4) are provided on the side of the stirring rod (5-3). The multiple side holes (5-4) are arranged at intervals along the circumference of the stirring rod (5-3), and the centers of all the side holes (5-4) are located on the same radial plane. The radial plane is located between the stirring rod (5-3) and the bottom hole. Below and close to the connection of the outer impeller (5-1); an axial bottom hole (5-5) is provided on the end face of the bottom end of the stirring rod (5-3), and the side hole (5-4) and the bottom hole (5-5) are both connected to the cavity inside the stirring rod (5-3); an outer impeller (5-1) and an inner impeller (5-2) are installed on the stirring rod (5-3), the outer impeller (5-1) is coaxially arranged outside the inner impeller (5-2), and the inner impeller (5-2) is located at the bottom of the stirring vessel (6).

3. The fine-grained soil dynamic mixing device according to claim 2, characterized in that: The side hole (5-4) is elliptical in shape, and the major axis of the elliptical side hole (5-4) is arranged along the axial direction of the stirring rod (5-3).

4. The fine-grained soil dynamic mixing device according to claim 2, characterized in that: The inner propeller (5-2) is a single-layer propeller, and the blade angle of the inner propeller (5-2) is 30° to 60°.

5. A fine-grained soil dynamic mixing device according to any one of claims 2 or 4, characterized in that: The inner impeller (5-2) is fitted onto the bottom of the stirring rod (5-3). The bottom end of the stirring rod (5-3) extends from the center of the inner impeller (5-2) to form an extension. The extension is a frustum-shaped part that is narrow at the top and wide at the bottom. A through hole is opened along the axial direction on the bottom end face of the extension to form a bottom hole (5-5).

6. The fine-grained soil dynamic mixing device according to claim 1, characterized in that: The monitoring unit includes several particle concentration probes (8) and one conductivity probe (9); all particle concentration probes (8) are arranged sequentially at intervals along the axial direction of the stirred tank (6); the conductivity probe (9) is arranged on the side wall at the bottom of the stirred tank (6). The monitoring unit also includes a particle concentration monitor (10) and a conductivity monitor (11). The particle concentration probe (8) is electrically connected to the particle concentration monitor (10), and the conductivity probe (9) is electrically connected to the conductivity monitor (11).

7. The fine-grained soil dynamic mixing device according to claim 1, characterized in that: The mixing vessel (6) is provided with a sand cushion layer (7), which is laid at the bottom of the mixing vessel (6).

8. A fine-grained soil dynamic mixing device according to claim 1, characterized in that: The bottom of the mixing vessel (6) is provided with a water outlet, which is connected to the interior of the mixing vessel (6) and is connected to the collection box (14) through a conduit (12); the height of the water outlet is greater than the height of the connection between the conduit (12) and the collection box (14).

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