A contaminated soil grading dual-channel remediation device

Abstract

The present application relates to a kind of contaminated soil grading dual-channel repair equipment, including feeding device, multistage screening device, repair device, unloading device and waste gas recovery device;Feeding device is used to transport contaminated soil to the multistage screening device;Multistage screening device is provided with multistage screening aperture, for selecting soil particle size screening according to soil pollution gradient;Repair device receives the soil screened after multistage screening device, and according to soil particle size and pollution type, select the kind of reagent, concentration, and determine repair process, carry out leaching or thermal desorption repair;Unloading device is used to unload the soil after repair of repair device, or send back high concentration contaminated soil and carry out intermittent cycle repair.Compared with prior art, the present application realizes the purpose of fast, efficient, energy-saving, uniform and sufficient repair of contaminated soil, especially for low permeability soil, different pollutant gradient mixed soil, using different reagent combination has obvious effect.

Description

Technical Field

[0001] This invention relates to the field of environmental protection technology, and in particular to a graded dual-channel remediation device for contaminated soil. Background Technology

[0002] Soil pollution refers to the phenomenon where pollutants generated by human activities enter the soil through various pathways and accumulate to a level exceeding the soil's capacity for containment and purification, leading to soil quality deterioration and harm. When there are excessive harmful substances in the soil, it will cause changes in the soil's composition, structure, and function, inhibiting microbial activity. Ultimately, these harmful substances or their decomposition products will endanger human health.

[0003] Soil remediation refers to the use of physical, chemical, and biological methods to transfer, absorb, degrade, and transform pollutants in soil, reducing their concentration to acceptable levels or converting toxic and harmful pollutants into harmless substances. Soil leaching technology utilizes the fluidity of the leaching solution and its reaction characteristics with pollutants to remove soil contaminants. It achieves the transfer of pollutants from the solid phase to the liquid phase through separation or desorption. Soil leaching technology is attracting attention in the remediation field due to its stable effects, simple process, pollutant concentration, reduction of contaminated soil volume, and ability to remove pollutants from the soil. It can simultaneously treat inorganic or organic contaminated soil and is one of the few remediation methods that can permanently treat heavy metal pollution. Thermal desorption, as a non-combustion technology, has a wide range of pollutant treatment capabilities, mobile equipment, and allows for the reuse of remediated soil. Its non-oxidative combustion treatment method avoids dioxin formation and is widely used for the remediation of organic pollutant-contaminated soil. Currently, existing remediation devices are mostly used for single-purpose remediation of heavy metal-contaminated soil or single-purpose remediation of organic-contaminated soil. When the soil contamination is a mixture of heavy metals and organics, separate remediation is required, leading to resource waste, reduced remediation selectivity, and increased costs.

[0004] The distribution of soil pollution gradients is closely related to soil particle size. Smaller soil particles have higher pollution concentrations, requiring higher concentrations of remediation agents and resulting in higher costs; conversely, larger soil particles have lower pollution concentrations, requiring lower concentrations of remediation agents and resulting in lower costs. Currently, remediation processes generally do not involve grading. This leads to over-remediation and resource waste in the remediation of large-particle contaminated soil, while insufficient concentrations of remediation agents result in unsatisfactory remediation effects in small-particle contaminated soil. Current remediation equipment suffers from drawbacks such as insufficient leaching of the soil interior due to factors including the type and state of pollutants, resistance to the transfer of leaching agents in contaminated soil, and the treatability and recyclability of the leaching solution. This results in unsatisfactory treatment effects on low-permeability soils, low pollutant removal rates, uneven mixing, lack of leaching solution recycling, and serious secondary pollution. Summary of the Invention

[0005] The purpose of this invention is to overcome the shortcomings of the existing technology by providing a selective leaching / thermal desorption remediation system that allows for the conversion or simultaneous use of heavy metal leaching remediation and organic matter thermal desorption remediation systems without the need for equipment reassembly. The equipment selects the screen aperture based on the soil particle size and pollution concentration distribution. The screen aperture can be directly adjusted according to operating parameters without replacing the screen. The type and concentration of leaching agents are selected based on soil particle size requirements for segmented or combined remediation. Contaminated soil is sieved into different particle sizes using a selective particle size sieving device. After sieving, the contaminated soil enters the remediation equipment, where it settles from top to bottom due to gravity. This invention utilizes a combination of high-pressure bubbles generated by aeration equipment and mechanical stirring. The remediation liquid, bubbles, and hot steam flow upwards against the contaminated soil, thoroughly stirring and leaching it, achieving efficient, uniform, and graded combined remediation of heavy metal and organic matter contaminated soils. It is particularly effective for contaminated soils with low permeability, viscosity, and significant variations in pollution concentration with particle size distribution. The leaching liquid and steam can be recycled and reused, minimizing the risk of external pollution and offering high remediation selectivity.

[0006] The objective of this invention can be achieved through the following technical solutions: This invention provides a graded dual-channel remediation device for contaminated soil, including a feeding device, a multi-stage screening device, a remediation device, a discharging device, and a waste gas recovery device; The feeding device is used to transport contaminated soil to the multi-stage screening device; The multi-stage screening device is equipped with multiple screening apertures, which are used to select soil particle size for screening according to the soil pollution gradient. The remediation device receives soil after sieving by a multi-stage screening device, selects the type and concentration of the agent according to the soil particle size and the type of pollution, and determines the remediation process, performing leaching or thermal desorption remediation. The unloading device is used to unload the soil after it has been repaired by the remediation device, or to send back high-concentration contaminated soil for intermittent cyclic remediation.

[0007] Furthermore, the multi-stage screening device includes, in series, a first-stage fine-aperture screening device, a second-stage medium-aperture screening device, and a third-stage coarse-aperture screening device, wherein the sieve apertures decrease in a stepped manner.

[0008] Furthermore, the multi-stage screening device also includes a first-stage discharge hopper, a second-stage discharge hopper, and a third-stage discharge hopper respectively installed on a first-stage fine-aperture screening device, a second-stage medium-aperture screening device, and a third-stage coarse-aperture screening device.

[0009] Furthermore, the first-stage fine-aperture screening device, the second-stage medium-aperture screening device, and the third-stage coarse-aperture screening device all include a screening device body, a screen mesh disposed in the device body, and transverse fixed connecting rods respectively connected to the screen mesh and the screening device body; The unloading hoppers are all hinged below each screening device.

[0010] The main body of the screening equipment is a vibrating screen or a rotary screen; The screen has a double-layer structure. The inner screen is fixed in the main body of the screening equipment, and the outer screen can be displaced relative to the inner screen. The adjustable screening aperture is formed by the degree of overlap of the screen holes on the inner and outer screens.

[0011] Furthermore, the repair device includes: The multi-stage rinsing / thermal desorption device includes multiple independent remediation units, each of which can operate independently and perform rinsing or thermal desorption processes on the soil screened by the multi-stage screening device. Chemical treatment unit: Provides the necessary chemicals for the multi-stage rinsing / thermal desorption unit, and adjusts different types and concentrations of chemicals according to different soil particle sizes and pollutant concentrations in the multi-stage rinsing / thermal desorption unit.

[0012] Furthermore, the independent repair unit in the multi-stage rinsing / thermal desorption device includes a first-stage rinsing / desorption device, a second-stage rinsing / desorption device, and a third-stage rinsing / desorption device; The first-stage unloading hopper, the second-stage unloading hopper, and the third-stage unloading hopper are respectively connected to the first-stage rinsing / desorption device, the second-stage rinsing / desorption device, and the third-stage rinsing / desorption device; The first-stage rinsing / desorption device, the second-stage rinsing / desorption device, and the third-stage rinsing / desorption device all include a rinsing / desorption device housing and a rinsing liquid sprayer disposed in the rinsing / desorption device housing.

[0013] Furthermore, the repair device also includes a steam / exhaust gas treatment device disposed in the housing of the rinsing / desorption device, the steam / exhaust gas treatment device being used for aeration and stirring during rinsing or steam injection during thermal desorption.

[0014] Furthermore, the steam / exhaust gas treatment device includes a steam generator and an aeration device; The steam generator is connected to the air inlet of each independent repair unit to provide steam to each repair unit. The aeration devices are connected to the air inlets of each independent repair unit to provide air to each repair unit.

[0015] Furthermore, the steam / exhaust gas treatment device also includes: A filter, connected to the exhaust port of each individual repair unit, is used to filter the exhaust gas emitted by each individual repair unit; A heat exchanger, connected to the filter, is used to exchange heat from the exhaust gas to a preset temperature range; Catalytic converter: connected to the heat exchanger, used to catalytically convert harmful substances in the exhaust gas into harmless or low-toxicity substances.

[0016] Furthermore, the unloading device includes a starting screw conveyor, an unloading trough, an auxiliary unloading device, and a drying device; The screw conveyors are located in each independent repair unit; The soil unloading trough is located at one end of the screw conveyor; An auxiliary unloading device is located above the unloading trough. The auxiliary unloading device includes at least one rotating impeller. The auxiliary unloading device is used to prevent the unloaded soil from accumulating. When the auxiliary unloading device rotates forward, it pushes the soil to the remediated soil unloading hopper and enters the continuous remediation mode. It performs intermittent cyclic remediation for high-concentration contaminated soil. When the auxiliary unloading device rotates in reverse, it stirs and transports the contaminated soil upward to a first-stage rinsing / desorption device. It is then transported back to the bottom hollow spiral device by aeration / steam stirring to form an internal cyclic remediation. After the remediation target is achieved, the auxiliary unloading device rotates forward to push the soil into the remediated soil unloading hopper. The drying device is an air dryer, which is connected to the unloading trough via pipeline; The screw conveyor is started, and the contaminated soil flows from top to bottom in the opposite direction to the leaching agent. After remediation, the soil settles to the bottom of the remediation pool and is then transported to the unloading trough by the screw device. The soil in the unloading trough will accumulate. The auxiliary unloading device is started, and the remediated soil enters the unloading trough. During the conveying process, the soil is further deeply leached by the screw agitation to improve the remediation efficiency. The remediated soil is transported to the drying device through pipelines, and the dried soil is discharged to the outside.

[0017] Compared with the prior art, the present invention has the following beneficial effects: This invention employs an air-mechanical combination as the stirring medium, utilizing a segmented and graded remediation process. It combines heavy metal leaching with organic thermal desorption in a dual-channel operation, eliminating the need for additional equipment and allowing for direct conversion or simultaneous use. This achieves efficient, uniform, graded, combined, and selective remediation of soils contaminated with heavy metals and organic matter, with particularly significant effects on soils with low permeability, viscosity, and multiple particle sizes. High-pressure air aeration / hot steam combined with mechanical stirring effectively desorbs solid and free pollutants on soil particles and surfaces. The antagonistic contact between soil and the leaching solution / bubbles / steam is more effective and uniform than ordinary mechanical stirring. The invention features a rotating stirring paddle / aeration pipe / steam pipe design, ensuring high efficiency and easy maintenance. The remediation solution / aeration / steam is treated and returned to the remediation device for recycling, reducing secondary pollution. A dosing tank is used to replenish losses from the leaching solution and adjust reagent concentration. A screw conveyor and auxiliary devices at the bottom of the remediation tank allow for intermittent / continuous auxiliary remediation. The simple structure, low cost, and compact size enable sealed transport and reverse transport, facilitating the clearing of blocked soil in the unloading trough. The remediation equipment of this invention can be used as a single unit for remediation, or in combination with other units as needed. Parameters such as remediation time, leaching solution concentration, stirring density, stirring intensity, heavy metals, and organic matter content can all be adjusted according to the degree of soil pollution. Attached Figure Description

[0018] Figure 1 This is a schematic diagram of the screening-repair structure in this application; Figure 2 This is a schematic diagram of the adjustable screening equipment in this application; Figure 3 This is a schematic diagram of the rinsing / thermal desorption repair equipment in this application; Figure 4-1 This is a schematic diagram of the bubble / steam agitator structure in this application; Figure 4-2 This is a schematic diagram of the main shaft structure of the agitator in this application; Figure 4-3 This is a schematic diagram of the agitator blade structure in this application; Figure 4-4 This is a schematic diagram of the unloading plate structure in this application.

[0019] Explanation of reference numerals in the attached drawings: 1. Feeding device; 2. Crushed stone discharge device / combined connection device; 3. Multi-stage screening device; 31. First-stage fine aperture screening equipment; 311. First screening connection device; 312. Adjustable screening aperture; 313. Aperture fixing frame; 314. Second screening connection device; 315. First-stage screening discharge hopper; 316. Second-stage screening discharge hopper; 317. Third-stage screening discharge hopper; 32. Second-stage medium aperture screening equipment; 33. Third-stage coarse aperture screening equipment; 34. Rotary gear; 35. Inclination adjustment table; 4. Multi-stage rinsing / thermal desorption unit; 41. First-stage rinsing / desorption unit; 411. First-stage repair and connection device; 42. Second-stage rinsing / desorption unit; 421. Second-stage repair and connection device; 43. Third-stage rinsing / desorption unit; 431. Third-stage repair and connection device; 412. Chemical preparation unit; 413. Screw conveyor (the central shaft and agitator are hollow with air holes for soil mixing and spraying); 414. Repair chemical overflow outlet; 415. Chemical purification unit; 416. High-pressure aeration / high-pressure steam unit; 417. Aeration / steam unit. 4171. Inner jet pipe; 4172. Outer jet pipe; 4173. Air vent of the agitator; 418. Bubble / steam collection device activated during aeration; 419. Polluted gas treatment device activated during aeration; 441. Remediated soil unloading hopper; 442. Auxiliary unloading device; 445. Soil drying device; 5. Drying treatment device; 6. Chemical treatment device; 61. Primary remediation chemical preparation device; 62. Secondary remediation chemical preparation device; 63. Tertiary remediation chemical preparation device; 7. Steam / exhaust gas treatment device. Detailed Implementation

[0020] The equipment in this invention includes: a feeding device 1, a screening link device / crushed stone outlet 2, an adjustable particle size screening device 3, a rinsing / thermal desorption device 4, a drying treatment device 5, a reagent treatment device 6, and a steam / tail gas treatment device 7. When using the rinsing process, the aeration device is connected to the air inlet device to generate microporous high-pressure bubbles, which agitate the contaminated soil from bottom to top. The aeration inlets are located on both sides of the remediation tank, and the remediation liquid, microporous bubbles, and contaminated soil flow in opposite directions, improving agitation efficiency. When using the thermal desorption process, the high-pressure steam device is connected to the air inlet device to generate high-temperature steam, which agitates the contaminated soil from bottom to top. The steam inlets are located on both sides of the remediation equipment, and the steam and contaminated soil flow in opposite directions, improving agitation efficiency.

[0021] Feeding Unit: Contaminated soil is transported by conveyor belt to an adjustable particle size screening device. The screening aperture is selected based on the soil contamination gradient. Below the feeding and screening device is a segmented leaching / thermal desorption remediation unit. Within the remediation unit, the smaller the contaminated soil particle size, the higher the reagent concentration; conversely, the larger the contaminated soil particle size, the lower the reagent concentration. The type and concentration of reagent are selected according to different pollutant types. The final discharge port is for bricks, gravel, and other debris. A sleeve connection device is installed at the end of the feeding unit. Given the significant differences in contamination concentration across different particle sizes of the contaminated soil, different numbers of remediation units can be selected for multi-stage combined remediation. Selecting the remediation process based on the contaminated soil particle size classification makes the remediation selective, reduces reagent usage, and saves costs.

[0022] Chemical inlet: The inlet is located at the bottom of the device, with multiple rows of perforated agitators evenly arranged. The remediation solution is pressurized and sprayed from the bottom, pre-treating the contaminated soil to form a slurry. The remediation solution then performs initial leaching of the contaminated soil from bottom to top. During operation, the soil and leaching agent flow in opposite directions due to gravity, increasing the contact area between the soil and the agent and improving leaching efficiency. After leaching, the leaching agent flows out from the side outlet. The effluent device is connected to the purification device; the treated remediation solution is re-mixed and reintroduced into the effluent device, allowing the remediation leaching agent to be recycled.

[0023] Aeration Device: Multiple rows of porous aeration and mixing pipes are located throughout the tank. These are rotatable high-pressure jet pipes, and each set of porous aeration pipes has an adjustment device. The jet volume and bubble size can be directly adjusted according to the operating process parameters, eliminating the need for equipment replacement. The rotation of the aeration pipes provides initial mechanical mixing, while the high-pressure gas jets create microbubbles for uniform mixing of contaminated soil. The aeration holes are located away from the rotating pipes to prevent pore blockage during mixing. When using the organic matter thermal desorption process, the aeration device is a high-pressure hot steam device, allowing direct integration into the organic matter thermal desorption process without equipment replacement.

[0024] Leaching device: The chemical feeding device is located at the bottom of the remediation tank. After the remediation liquid is injected, the aeration equipment is activated, and high-pressure gas is sprayed upward from the bottom in a rotating manner. The bubbles carry the contaminated soil and leaching agent upward by their own buoyancy, increasing the leaching contact surface and the uniformity of the soil.

[0025] The leaching and mixing process controls the residence time of the leaching solution by controlling the flow rate of the remediation solution, and controls the mixing intensity by controlling the aeration volume, aeration hole size, and density of the aeration equipment. This addresses the shortcomings of poor permeability of small-sized or cohesive soil particles, reduces dead zones in the mixing process, and enhances the ability of the leaching agent to fully mix with pollutants.

[0026] Unloading device: The unloading device consists of a screw conveyor, unloading trough, conveying device, and filter press. The screw conveyor is located at the bottom of the scrubbing tank and is used to clean the soil after scrubbing. The unloading trough is located below the scrubbing tank and is in the shape of an inverted trapezoidal cone.

[0027] The soil unloading device is used for unloading clean soil after remediation. An inverted trapezoidal unloading trough is installed at the bottom of the remediation tank. A hollow spiral device sprays remediation chemicals while simultaneously pushing the remediated soil into the trapezoidal unloading trough. Spiral unloading and remediation occur simultaneously, and the device can operate continuously or intermittently. For continuous operation of low-concentration contaminated soil, a spiral agitator pushes clean soil into the unloading trough and into the slurry conveying pipe, which then sends it to a filter press for drying and dewatering. Above the unloading trough is an auxiliary unloading device. This device operates forward to prevent soil accumulation and pushes the remediated soil into the unloading trough, initiating continuous remediation. For high-concentration contaminated soil, intermittent cyclic remediation is performed. The auxiliary unloading device rotates counter-clockwise, agitating and transporting the contaminated soil upwards. Through aeration / steam agitation, the soil is then transported back to the bottom hollow spiral device, forming an internal cyclic remediation system. Once the remediation target is achieved, the auxiliary unloading device rotates forward, and the remediated soil enters the unloading trough.

[0028] Repair fluid circulation treatment device: The circulation treatment device of the present invention removes impurities by filtering, settling and adsorbing, thereby improving the reuse rate of repair rinsing fluid.

[0029] Dosing device: After the remediation solution undergoes circulation treatment, there may be a loss in the concentration or total amount of the reagents. The dosing device adds reagents or water to the remediation solution and sets the appropriate concentration before circulating it back into the remediation tank.

[0030] Waste gas recovery device: During the repair operation, the repair device operates in a closed or negative pressure manner. An exhaust pipe is installed on the top of the device. If the soil contains volatile organic compounds or waste gas is generated during the repair, it can be treated by the waste gas recovery device and recycled to reduce secondary pollution.

[0031] The present invention will now be described in detail with reference to the accompanying drawings and specific embodiments. Component models, material names, connection structures, control methods, algorithms, and other features not explicitly described in this technical solution are considered common technical features disclosed in the prior art.

[0032] Example 1 This embodiment selects a dual-channel remediation system of leaching / thermal desorption, which allows for the conversion or simultaneous use of heavy metal leaching remediation and organic matter thermal desorption remediation systems without the need for equipment reassembly. The equipment selects the screen aperture based on the soil particle size and pollution concentration. The screen aperture can be adjusted according to operating parameters without replacing the screen. The type and concentration of leaching agents are selected based on soil particle size requirements for segmented or combined remediation. The system includes: a feeding device 1, a screening link device / gravel outlet 2, an adjustable particle size screening device 3, a leaching / thermal desorption device 4, a drying treatment device 5, a reagent treatment device 6, and a steam / exhaust gas treatment device 7.

[0033] The schematic diagram shows a single remediation unit. This unit includes a soil screening and conveying device with a screening inlet 1 and a screening outlet 2. The screening outlet is equipped with a sleeve connecting device (specifically a cylindrical structure with connectors at both ends for connection to other equipment) for linking different remediation units (the link in this invention can be interpreted as a coupling connection) for combined use, or for individual use. By stretching the screen... Figure 2 This allows for adjustment of the adjustable sieve aperture size of 312. For example... Figure 2 As shown, the tension screen has a double-layer structure. The inner layer is fixed, while the outer layer can move left and right. Moving the outer and inner screens causes displacement, resulting in the screen aperture 312 increasing or decreasing in size. The first screening link device 311 and the second screening link device 314 form the main frame, used for connecting the various screens. The fixing frame 313, located on the screen, is used to fix and support the screen after movement, preventing deformation. The relative fixation of the outer and inner screens can be achieved by limiting the screening link devices with bolts or clamps.

[0034] Soil leaching unit 4 is located at the lower end of spiral screening device 3, and is subjected to high-pressure aeration / steam stirring with aeration leaching equipment 7; after stirring and separation by spiral conveyor separation equipment, it enters drying device 445; the leachate treatment equipment system, including reagent preparation device 412, spiral conveyor 413, remediation agent overflow port 414, and reagent purification device 415, is connected in sequence for reagent preparation and recycling; the leachate dosing equipment is connected to aeration / steam enhanced leaching equipment and leachate circulation and purification equipment respectively. The gas generated by the aeration equipment enters the remediation tank through multiple rows of porous pipes for gas stirring and leaching. The equipment performs heavy metal leaching remediation process, adjusting and controlling the pore size to enter the contaminated soil for remediation, and the exhaust gas passes through a collection device, the pollutant-containing gas enters a collection and treatment device, and the clean air enters a high-pressure device for recycling. The equipment performs thermal desorption remediation process, the steam enters the stirring device through a high-pressure steam device, the pore size is adjusted to enter the contaminated soil for remediation, and the exhaust gas passes through a collection device, the pollutant-containing gas enters a collection and treatment device, and the clean air enters a high-pressure device for recycling.

[0035] 1. First Workflow: See Figure 5 Contaminated soil enters the spiral screening device via the feed conveyor belt and screening inlet 1. Different screening apertures are selected according to technical requirements, corresponding to the type and concentration of the reagents chosen in the lower remediation device. The screened soil then enters the lower remediation device under gravity. Soil with apertures larger than the required size enters the next stage for remediation based on the screening results. Soil that meets the standards, or gravel and bricks, exits the screening device and is stockpiled.

[0036] 2. Second Workflow: The purified remediation agent enters the agent mixing device 412, where it is prepared according to the soil contamination concentration and particle size. The remediation agent enters the remediation tank via a screw conveyor 413. The inlet is located at the bottom of the remediation tank, and the remediation solution is injected from the bottom inlet to flush the contaminated soil in the opposite direction, pre-treating and rinsing the soil to form a slurry. The remediation solution passes through the contaminated soil from the bottom to the upper outlet pipe, entering the leaching solution purification tank 415. The purified leaching solution re-enters the agent mixing device 412 for further mixing and then returns to the remediation tank for recycling.

[0037] 3. Third Working Process: Aeration / Steam Device 6 provides aeration / steam. The aeration / steam pipes are located in the main body of the remediation tank, employing multiple rows of perforated unidirectional pipes. Each group of perforated aeration pipes has a regulating valve, and the air holes face away from the direction of rotation to prevent clogging. During operation, gas is injected from multiple exhaust holes, spirally stirred, and the high-pressure injected gas flows upward, agitating and floating to mix with the contaminated soil and leachate. The remediation tank is a closed or negative pressure device, and the gas rises into the gas collection and treatment device. Heavy metal pollution is handled through the aeration device channel, while organic pollution is handled through the steam device channel.

[0038] 4. Fourth Work Process: The screw conveyor 413 is started, and the contaminated soil flows downwards against the leaching agent. After remediation, the soil settles to the bottom of the remediation tank and is then transported by the screw conveyor to the remediated soil unloading hopper 441. Soil accumulates at the unloading hopper. The auxiliary unloading device 442 is then activated, and auxiliary soil enters the remediated soil unloading hopper 441. During the conveying process, the screw conveyor further leaches the soil, improving remediation efficiency. The remediated soil is then transported via pipeline to the drying device 445. Screw unloading and remediation occur simultaneously; the device can operate continuously or intermittently. For continuous operation processes involving low-concentration contaminated soil, the screw conveyor pushes clean soil to the unloading trough, which then enters the slurry conveying pipe and is sent to the filter press for drying and dewatering. Above the unloading trough is the auxiliary unloading device, which operates in the forward direction to prevent soil accumulation and pushes the remediated soil to the unloading trough, entering the continuous remediation mode. For highly contaminated soil, intermittent cyclic remediation is employed. An auxiliary unloading device rotates counter-clockwise, agitating and transporting the contaminated soil upwards. It is then agitated again by aeration / steam and transported back to the bottom hollow spiral device, forming an internal cyclic remediation system. Once the remediation target is achieved, the auxiliary unloading device rotates clockwise, and the remediated soil enters the unloading trough.

[0039] 5. Fifth working process: The polluted soil contains volatile organic compounds or waste gas is generated during leaching. The waste gas can be recovered, treated and recycled to reduce secondary pollution.

[0040] In practice: Reference Figure 1A soil leaching / thermal desorption remediation device for contaminated soil includes an inlet 1, a crushed stone inlet 2, a multi-stage screening device 3, a multi-stage leaching / thermal desorption device 4, a clean soil drying device 5, a chemical treatment device 6, and a steam / exhaust gas treatment device. (Refer to...) Figure 1 , Figure 2 Contaminated soil enters the multi-stage screening device 3 through inlet 1. The screening aperture of the multi-stage screening device 3 can be adjusted as needed without replacing the screen. The screen can be selected as a single-stage, two-stage, three-stage, or higher-stage type depending on the usage requirements. The screened gravel is discharged and stored through outlet 2. Soil of different particle sizes is classified according to the pollution gradient, and the type / concentration of leaching and thermal desorption steam are selected before entering their respective multi-stage treatment devices. The number of treatment devices corresponds to the number of stages of the screening device. The equipment can be used individually or in combination with multiple units connected through the gravel outlet 2, depending on the technical requirements. The equipment selects the thermal desorption process based on the type of contaminated soil, such as heavy metal leaching or organic matter leaching. The cleaned soil after remediation is treated by the drying treatment device 5. The multi-stage remediation device 4 includes three auxiliary remediation devices: the drying treatment device 5, the chemical treatment device 6, and the steam / exhaust gas treatment device 7.

[0041] Reference Figure 1 , Figure 2 The contaminated soil enters a multi-stage screening device through inlet 1. The screening devices are connected sequentially, each equipped with the required screen mesh. The screen mesh apertures are arranged in small, medium, and large sizes according to the soil remediation process, and can be adjusted at any time based on site parameters after installation. The screen mesh aperture 312 is adjusted by rotation and stretching, and the screening device and aperture size are fixed by a transverse fixing link 313. The three-section screen is connected by a screen mesh linking device, with different aperture meshes installed sequentially. A rotating gear 34 adjusts the soil feeding speed and the soil particle size by controlling the gear rotation speed. A lifting platform 35 adjusts the soil feeding speed and the soil particle size by controlling the screen tilt angle. The screened soil enters its respective remediation chamber through three unloading hoppers: a first-stage unloading hopper 315, a second-stage unloading hopper 316, and a third-stage unloading hopper 317.

[0042] Reference Figure 1 , Figure 3 After the contaminated soil enters the three-stage remediation device, there are three remediation connection devices: 411, 421, and 431. Figure 4-4Each section of the remediation connection device includes an openable and closable sealed unloading plate. When the screened soil is fed in, the unloading plate automatically opens due to the gravity of the soil. When the equipment needs to be operated in a closed manner, feeding is stopped, and the unloading plate closes, allowing the remediation equipment to operate in a closed manner. The device operates in a closed or negative pressure manner to prevent exhaust gas and pollutants from entering the atmosphere. The concentration and type of remediation agent are adjusted according to requirements. The agent enters the remediation equipment through a stirring device, and the remediation agent flows from bottom to top, forming a counter-current flow with the contaminated soil to increase the remediation contact area. The remediation agent flows out from the liquid outlet device 414 and enters the leaching liquid purification device 415 to remove impurities. After purification, the liquid flows into the agent preparation device 412, and after adjusting the concentration according to the test, it re-enters the stirring and liquid inlet device 413 for recycling.

[0043] When the remediation contaminant is heavy metal, shut down the high-pressure steam treatment unit and start the high-pressure aeration unit for rinsing remediation. (Refer to...) Figure 1 , Figure 3 Figure 4 shows the high-pressure aeration / steam equipment 416 generating high-pressure gas which is injected through a pipeline into the high-pressure aeration and mixing device 417. The high-pressure aeration device is located in the main body of the remediation device, operating in opposite directions on both sides. During operation, high-pressure gas is ejected from 417, and the gas moves upwards. During operation, the mixing assists aeration, and the remediation liquid reacts evenly with the contaminated soil. The gas is recovered and processed by the collection device 418, and the gas containing pollutants enters the collection and treatment device 419 for collection and treatment. Clean gas enters the gas recycling pipeline and returns to the high-pressure aeration device 416 for reuse.

[0044] When the pollutant to be remediated is organic matter, the high-pressure aeration device is shut down and the thermal desorption device is activated for thermal desorption remediation. High-pressure steam is introduced into device 416 and then into the steam agitator, which operates in opposite directions on both sides. During operation, high-pressure steam is ejected from 417, and the gas rises from bottom to top. During operation, the agitator assists in aeration, ensuring uniform reaction between the washing liquid and the contaminated soil. The gas is recovered and processed by the gas collection device 418, while the gas containing pollutants enters the collection and treatment device 419 for further processing. The clean gas enters the gas recycling pipeline and is then recycled back into the high-pressure aeration / steam equipment 416.

[0045] Reference Figure 1 , Figure 3 Figure 4 shows that the bottom of the repair equipment has a high concentration of repair agent, which is in full contact with the soil. The soil repair effect is most obvious in the clean soil after repair. Therefore, the bottom is the unloading area for clean soil after repair. The stirring device 413 spirally propels the clean soil into the unloading hopper 441 after repair. The auxiliary unloading device 442 rotates to guide the unloaded soil into the unloading trough. The soil after repair enters the drying device 445 through the pipeline for soil dehydration. The output is clean soil after repair. The leaching liquid is recycled into the leaching liquid purification device 415 for recycling.

[0046] The spiral unloading and remediation processes occur simultaneously, and the system can operate continuously or intermittently. For continuous operation of low-concentration contaminated soil, the spiral agitator pushes clean soil into the unloading trough and into the slurry conveying pipe, which then sends it to the filter press for drying and dewatering. Above the unloading trough is an auxiliary unloading device. This device operates in the forward direction to prevent soil accumulation and pushes the remediated soil back into the unloading trough, initiating continuous remediation. For high-concentration contaminated soil, intermittent cyclic remediation is performed. The auxiliary unloading device rotates in the reverse direction, agitating and transporting the contaminated soil upwards. Through aeration / steam mixing, the soil is then transported back to the bottom hollow spiral device, forming an internal cyclic remediation system. Once the remediation target is achieved, the auxiliary unloading device rotates in the forward direction, and the remediated soil returns to the unloading trough.

[0047] Referring to Figure 4, the aeration and mixing device has a hollow structure 4171. It uses high-pressure gas or steam and is connected to a crescent-shaped mixing paddle. The paddle has an air hole 4173 for injecting gas / steam. The air hole is located on the back of the paddle to prevent it from being blocked by soil during rotation. It also includes an inner tube injection hole 4171 and an outer tube injection hole 4172. According to technical requirements, the injection hole diameter is adjusted by rotating the outer tube to create a cross angle with the inner tube, thereby adjusting the size and flow rate of the injected gas bubbles without requiring replacement of the pipe diameter equipment.

[0048] refer to Figure 1 , Figure 3 Figure 4 shows that the three stages—fine-pore screening device 31, medium-pore screening device 32, and coarse-pore screening device 33—have similar structures. They utilize screens with different particle size control ranges to screen contaminated soil of different particle sizes according to technical requirements, which are then fed into the remediation equipment. The screen apertures of all three stages can be directly adjusted without replacing the screens. Different types and concentrations of remediation agents are prepared according to the soil particle size and contaminant concentration. The three remediation agent preparation devices—stage 1 (fine-pore), stage 2 (medium-pore), and stage 3 (coarse-pore)—are all solid / liquid or liquid / liquid mixing devices. Agents and solvents are added and mixed evenly according to design requirements. The agent concentration and type are adjusted as needed before being fed into their respective remediation devices. This allows for the remediation of different types and concentrations of contaminants without requiring equipment replacement, enabling integrated remediation.

[0049] The above description of the embodiments is provided to enable those skilled in the art to understand and use the invention. It will be apparent to those skilled in the art that various modifications can be made to these embodiments, and the general principles described herein can be applied to other embodiments without inventive effort. Therefore, the present invention is not limited to the above embodiments, and any improvements and modifications made by those skilled in the art based on the disclosure of the present invention without departing from the scope of the invention should be within the protection scope of the present invention.

Claims

1. A graded dual-channel remediation device for contaminated soil, characterized in that, It includes a feeding device, a multi-stage screening device, a repair device, a discharge device, and a waste gas recovery device; The feeding device is used to transport contaminated soil to the multi-stage screening device (3). The multi-stage screening device (3) includes, in series, a first-stage fine-aperture screening device (31), a second-stage medium-aperture screening device (32), and a third-stage coarse-aperture screening device (33). The remediation device receives soil after sieving by the multi-stage sieving device (3), selects the type and concentration of the agent according to the soil particle size and the type of pollution, and determines the remediation process to carry out rinsing or thermal desorption remediation. The unloading device is used to unload the soil after it has been repaired by the remediation device, or to send back high-concentration contaminated soil for intermittent cyclic remediation. The repair device includes: The multi-stage rinsing / thermal desorption device (4) includes multiple independent remediation units, each of which can operate independently and perform rinsing or thermal desorption processes on the soil screened by the multi-stage screening device (3). Chemical treatment device (6): Provides the required chemicals for the multi-stage rinsing / thermal desorption device, and adjusts different types and concentrations of chemicals according to different soil particle sizes and pollutant concentrations in the multi-stage rinsing / thermal desorption device (4); The independent repair unit in the multi-stage rinsing / thermal desorption device (4) includes a first-stage rinsing / desorption device (41), a second-stage rinsing / desorption device (42), and a third-stage rinsing / desorption device (43). The first-stage rinsing / desorption device (41), the second-stage rinsing / desorption device (42), and the third-stage rinsing / desorption device (43) all include a rinsing / desorption device housing and a rinsing liquid sprayer disposed in the rinsing / desorption device housing; The repair device also includes a steam / exhaust gas treatment device (7) disposed in the housing of the rinsing / desorption device. The steam / exhaust gas treatment device (7) includes a steam generator and an aeration device; The unloading device includes a screw conveyor (413), a soil unloading hopper (441) after remediation (441), an auxiliary unloading device (442), and a drying device (445). The screw conveyor (413) is located in each independent remediation unit. The screw conveyor (413) is a hollow structure with air holes and is used for soil mixing and spraying. The soil unloading hopper (441) after repair is located at one end of the screw conveyor (413); An auxiliary unloading device (442) is located above the remediated soil unloading hopper (441). The auxiliary unloading device (442) includes at least one rotating impeller. The auxiliary unloading device (442) is used to prevent the unloaded soil from accumulating. When the auxiliary unloading device (442) rotates in the forward direction, it pushes the soil into the remediated soil unloading hopper (441) and enters the continuous remediation mode. It performs intermittent cyclic remediation for high-concentration contaminated soil. When the auxiliary unloading device (442) rotates in the reverse direction, it stirs and transports the contaminated soil upward to a first-stage rinsing / desorption device (41). It is then transported back to the bottom hollow spiral device by aeration / steam stirring to form an internal cyclic remediation. After the remediation target is achieved, the auxiliary unloading device (442) rotates in the forward direction and pushes the soil into the remediated soil unloading hopper (441).

2. The graded dual-channel remediation device for contaminated soil according to claim 1, characterized in that, The multi-stage screening device (3) includes a first-stage discharge hopper (315), a second-stage discharge hopper (316), and a third-stage discharge hopper (317) respectively installed on a first-stage fine-aperture screening device (31), a second-stage medium-aperture screening device (32), and a third-stage coarse-aperture screening device (33). The first-stage unloading hopper (315), the second-stage unloading hopper (316), and the third-stage unloading hopper (317) are respectively connected to the first-stage rinsing / desorption device (41), the second-stage rinsing / desorption device (42), and the third-stage rinsing / desorption device (43).

3. The graded dual-channel remediation device for contaminated soil according to claim 1, characterized in that, The steam / exhaust gas treatment device (7) further includes: A filter, connected to the exhaust port of each individual repair unit, is used to filter the exhaust gas emitted by each individual repair unit; A heat exchanger, connected to the filter, is used to exchange heat from the exhaust gas to a preset temperature range; A catalytic converter, connected to the heat exchanger, is used to catalytically convert harmful substances in the exhaust gas into harmless or low-toxicity substances.

4. The graded dual-channel remediation device for contaminated soil according to claim 1, characterized in that, The steam generator is connected to the air inlet of each independent repair unit to provide steam to each repair unit. The aeration devices are connected to the air inlets of each independent repair unit to provide air to each repair unit.

5. The graded dual-channel remediation device for contaminated soil according to claim 2, characterized in that, The first-stage fine-aperture screening device (31), the second-stage medium-aperture screening device (32), and the third-stage coarse-aperture screening device (33) all include a screening device body, a screen installed in the device body, and a transverse fixed connecting rod (313) that is connected to the screen and the screening device body respectively. The main body of the screening equipment is a vibrating screen or a rotary screen; The screen is a double-layer screen structure. The inner screen is fixed in the main body of the screening equipment, and the outer screen can be displaced relative to the inner screen. The degree of overlap of the screen holes on the inner and outer screens forms an adjustable screening aperture (312).

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