Chemical remediation treatment process and device for soil heavy metal pollution

Abstract

The application relates to the technical field of soil remediation, in particular to a chemical remediation treatment process and device for soil heavy metal pollution, which comprises an acid pickling tank, an acid pickling progress monitoring device, a solid-liquid separation device, a catalytic reaction tank and a stirring catalysis device; the acid pickling tank is used for soil acid pickling; the acid pickling progress monitoring device is connected with the acid pickling tank and is used for real-time monitoring of the soil acid pickling progress; the inlet of the solid-liquid separation device is connected with the acid pickling tank and is used for solid-liquid separation of a mixed solution obtained through soil acid pickling; the catalytic reaction tank is connected with the liquid phase outlet of the solid-liquid separation device and is used for containing the solution after soil acid pickling and reducing the heavy metal pollution of the solution through reaction; the stirring catalysis device is arranged in the catalytic reaction tank and is used for driving the catalyst and the solution to rotate reversely in the electrochemical oxidation tank. The chemical remediation treatment process and device for soil heavy metal pollution can effectively improve the soil remediation efficiency and remediation effect and is favorable for the resource utilization of heavy metals in the soil.

Description

A chemical remediation process and apparatus for soil heavy metal pollution Technical Field

[0001] This invention relates to the field of soil remediation technology, and more specifically, to a chemical remediation process and apparatus for heavy metal pollution in soil. Background Technology

[0002] Once heavy metal pollutants enter the soil, they are prone to accumulation, are highly concealed, are difficult to eradicate, and can easily enter the food chain, posing a threat to human health and ecosystem safety. They can cause serious damage to the farmland ecological environment and the living space of soil microorganisms. Some heavy metals can also be transformed into more toxic compounds. Therefore, the remediation and treatment of soil heavy metal pollution has become a matter of great concern to governments at all levels and scientists.

[0003] Soil acid washing is a remediation technology for contaminated soil. It involves mixing soil with chemical solvents to dissolve, separate, and treat pollutants, ultimately achieving soil purification and resource utilization. However, it's worth noting that current soil acid washing technologies still rely on experience to determine the endpoint. Some equipment involves extracting samples for solid-liquid separation and then testing the acid wash solution for multiple heavy metals. This process is time-consuming, labor-intensive, and requires frequent testing, resulting in extremely low efficiency. Furthermore, the types and amounts of heavy metals vary between different soils, leading to significant errors in sample testing and further contributing to the low efficiency of soil acid washing.

[0004] Furthermore, after acid washing and solid-liquid separation of some soils contaminated with heavy metals, the acid washing solution contains a high concentration of hexavalent chromium. The heavy metal ion pollution in the acid washing solution requires sufficient reaction to be removed, and adding appropriate catalysts can effectively improve reaction efficiency. For example, hexavalent chromium is highly toxic, exhibiting strong teratogenic, carcinogenic, and mutagenic effects, causing serious environmental pollution. Trivalent chromium, on the other hand, is an essential trace element for the human body. Both are the most common stable valence states, and the current common method for chromium removal is to reduce hexavalent chromium to trivalent chromium, and then increase the pH value to form Cr(OH)3 precipitate for recycling. A commonly used method for chromium reduction is electrochemical catalytic oxidation. In this reaction, iron and carbon are mixed to form a micro-electrolysis catalyst, utilizing the galvanic cell effect formed between iron and carbon to reduce hexavalent chromium in the liquid. Specifically, iron loses electrons at the anode and is oxidized to ferrous ions (Fe2+), while hexavalent chromium gains electrons at the cathode and is reduced to trivalent chromium. However, in practical applications, incomplete reactions and incomplete reduction of hexavalent chromium in the solution can easily occur, seriously affecting the elimination of heavy metal ion pollution and the resource-based reuse of heavy metals.

[0005] In summary, due to the difficulty in monitoring the progress of soil heavy metal acid washing and the low efficiency of heavy metal pollution ion removal, the existing soil remediation technology is not effective, and there is an urgent need to improve the chemical remediation process and equipment for soil heavy metal pollution. Summary of the Invention

[0006] To overcome the problem of poor soil remediation effect in the prior art, the present invention provides a chemical remediation process and apparatus for soil heavy metal pollution.

[0007] To address the aforementioned technical problems, the first aspect of this invention provides a chemical remediation treatment apparatus for heavy metal pollution in soil.

[0008] A second aspect of the present invention provides a chemical remediation process for soil heavy metal pollution.

[0009] A chemical remediation device for soil heavy metal pollution includes: an acid washing tank, an acid washing progress monitoring device, a solid-liquid separation device, a catalytic reaction tank, and a stirring catalytic device. The acid washing tank is used for soil acid washing. The acid washing progress monitoring device is connected to the acid washing tank to monitor the soil acid washing progress in real time. The inlet of the solid-liquid separation device is connected to the acid washing tank to perform solid-liquid separation on the mixture obtained from soil acid washing. The catalytic reaction tank is connected to the liquid phase outlet of the solid-liquid separation device to receive the solution obtained after solid-liquid separation and to react to reduce the valence state of chromium ions, thereby reducing the heavy metal pollution in the solution. The stirring catalytic device is set in the catalytic reaction tank to drive the catalyst and solution to rotate in opposite directions in the electrochemical oxidation tank.

[0010] In the technical solution of the present invention, the acid washing progress monitoring device can monitor the progress of soil acid washing in real time without repeated sampling for experimental measurement, thus improving the monitoring efficiency of soil acid washing; the stirring catalytic device can drive the solution and catalyst to rotate in opposite directions, so that the catalyst and solution can fully contact each other, thereby improving the chemical reaction efficiency. The chemical remediation treatment device for soil heavy metal pollution of the present invention can effectively improve the soil remediation effect.

[0011] Furthermore, the pickling progress monitoring device includes a float assembly, a linkage assembly, and an observation assembly. The float assembly is floating in the pickling tank. One end of the linkage assembly is connected to the float assembly for transmission, and the other end of the linkage assembly is connected to the observation assembly to drive the observation assembly to change.

[0012] In this scheme, as the acid washing process continues, heavy metal ions in the soil enter the solution, causing the solution density to gradually increase. The buoy assembly rises gradually with the increasing solution density, which in turn moves the linkage assembly, thus causing changes in the observation assembly. By observing these changes, the acid washing progress can be visually determined. When the observation assembly stabilizes, it indicates that the solution density has reached a stable level, signifying the end of the heavy metal acid washing process.

[0013] Furthermore, the pickling progress monitoring device also includes a filter assembly and a sludge scraping mechanism. The filter assembly is connected to the pickling tank and forms a filtration space in the pickling tank. The float assembly is placed in the filtration space. The sludge scraping mechanism is connected to the pickling tank and moves in contact with the outer surface of the filter assembly.

[0014] In this solution, a filtration space is formed in the pickling tank by a filtration component. On the one hand, the soil in the mixed liquor can be filtered out, and a relatively pure mixed liquor environment can be obtained in the filtration space. On the other hand, the disturbance caused by the mixing of the mixed liquor can be reduced, ensuring the relative stability of the floating component in the filtration space. The sludge scraping mechanism can scrape off the mud and sand adhering to the outer surface of the filtration component, thereby continuously ensuring the filtration effect of the filtration component.

[0015] Furthermore, the observation assembly includes a U-shaped tube, a piston tube, and a translational piston. The U-shaped tube is fixedly connected to the outer wall of the pickling tank and contains liquid. One end of the U-shaped tube is connected to the piston tube. The translational piston is fixedly connected to the linkage assembly and slidably connected in the piston tube.

[0016] In this scheme, the linkage component drives the translational piston to move in the piston tube, causing the liquid level at one end of the U-shaped tube to change, thus allowing for a direct observation of the progress of soil acid washing.

[0017] Furthermore, the stirring catalytic device includes a rotating mechanism, a driving mechanism, a stirring assembly, and a suspension chamber assembly. The rotating mechanism is disposed in the catalytic reaction tank. The stirring assembly and the suspension chamber assembly are respectively connected to the rotating mechanism. The suspension chamber assembly is used to carry the catalyst. The driving mechanism is connected to the rotating mechanism to drive the stirring assembly and the suspension chamber assembly to rotate in opposite directions simultaneously.

[0018] In this scheme, the driving mechanism drives the rotating mechanism to move, thereby causing the stirring assembly and the suspension chamber assembly to rotate in opposite directions simultaneously, promoting full contact between the catalyst in the suspension chamber assembly and the solution in the catalytic reaction tank, so as to improve the reaction conversion rate.

[0019] Furthermore, the suspension chamber assembly includes a catalyst chamber, a float, a retaining rod, and a suspension cylinder. The retaining rod is fixedly connected to the suspension cylinder and extends circumferentially. The catalyst chamber and the float are both annular and surround the outside of the suspension cylinder and are fixedly connected to the retaining rod respectively. The suspension chamber assembly is movably connected to the rotating mechanism in the vertical direction and rotates with the rotating mechanism.

[0020] In this scheme, buoyancy is provided by a float component, and the catalyst chamber and the float component are connected to the suspension cylinder by a fixing rod. Since the suspension chamber assembly is vertically connected to the rotating mechanism, it can always remain suspended in the solution as the liquid level changes, so that the catalyst in the suspension chamber assembly can always be in contact with the solution. At the same time, the suspension chamber assembly can rotate with the rotating mechanism, promoting further contact between the solution and the catalyst, and effectively carrying out the catalytic reaction.

[0021] Furthermore, the catalyst chamber has an inner cavity for containing the catalyst, and the side wall of the catalyst chamber has a liquid inlet hole communicating with the inner cavity. There are multiple catalyst chambers and multiple floats, and each catalyst chamber and each float is spaced apart in the circumference of the suspension cylinder.

[0022] In this design, the solution can react with the catalyst through the inlet hole, the multiple catalyst chambers spaced apart can promote the contact between the catalyst and the solution, and the spaced floats can provide stable buoyancy.

[0023] Furthermore, the rotating mechanism includes multiple vertically arranged shafts, each shaft rotating around the same vertical axis. The suspension chamber assembly has multiple through holes along the vertical direction, and each shaft passes through each through hole for movable connection.

[0024] In this design, multiple shafts are movably connected to the suspension chamber assembly through multiple through holes. At the same time, each shaft rotates around the same vertical axis, so that the suspension chamber assembly can float with the change of solution level while rotating with the rotating mechanism, ensuring that the catalyst is always in contact with the solution.

[0025] Furthermore, the side wall of the pickling tank is provided with a soil inlet, a feed hopper is connected to the outside of the soil inlet, and a rinsing net is connected to the inside of the soil inlet.

[0026] In this scheme, the soil to be pickled is placed in the feed hopper, and the mixed liquid in the pickling tank is continuously washed by the soil through the rinsing net, so that the soil is evenly spread in the pickling liquid and the soil pickling effect is improved.

[0027] This invention provides a chemical remediation process for soil heavy metal pollution, used in conjunction with the aforementioned apparatus, and includes the following steps:

[0028] S1: Soil contaminated with heavy metals is acid-washed in an acid washing tank;

[0029] S2: Observe the soil acid washing progress in the acid washing tank in real time until the soil acid washing is completed through the acid washing progress monitoring device;

[0030] S3: Solid-liquid separation is performed on the mixture obtained after pickling using a solid-liquid separation device;

[0031] S4: The solution obtained after solid-liquid separation is sent into the catalytic reaction tank. The solution and catalyst are rotated in opposite directions by a stirring catalytic device to promote the chemical reaction of heavy metal ions and reduce heavy metal pollution.

[0032] In this treatment process, the acid washing progress monitoring device eliminates the need for sampling experiments, thereby effectively improving the efficiency of soil acid washing progress monitoring and endpoint determination. The suspension catalytic stirring reaction device can improve the conversion rate of hexavalent chromium ions to trivalent chromium ions, enhance the soil remediation effect, and facilitate the subsequent resource utilization of heavy metals in the soil.

[0033] Compared with the prior art, the beneficial effects of the present invention are:

[0034] I. This invention is a chemical remediation treatment device for soil heavy metal pollution specifically designed based on the characteristics of soil heavy metal acid washing and the accumulated experimental results of the research group. Soil is screened and acid is washed by cyclone washing in an acid washing tank. After solid-liquid separation, the heavy metal pollutant ions are reacted in a catalytic reaction tank, for example, reducing hexavalent chromium to trivalent chromium. Using this chemical remediation treatment device for soil heavy metal pollution, on the one hand, all heavy metals in the soil can be acid-washed into the washing solution, thereby removing heavy metals from the soil; on the other hand, after solid-liquid separation, the solution containing soil heavy metal ions is fully reacted to reduce heavy metal pollution, which is beneficial for subsequent heavy metal recovery and utilization, enabling the resource utilization of heavy metals in the soil.

[0035] II. The chemical remediation treatment device for heavy metal pollution in soil of the present invention, by designing a float assembly, a linkage assembly and an observation assembly in the acid washing tank, reflects the density change of the mixed liquid containing heavy metal ions in the acid washing tank as the liquid level change of the U-shaped tube that can be directly observed, thereby intuitively monitoring the acid washing progress. Compared with sampling and experimental analysis, the efficiency is significantly improved, thereby greatly improving the efficiency of soil acid washing.

[0036] 3. The chemical remediation treatment device for heavy metal pollution in soil of the present invention, by setting a filter component and a sludge scraping component on the outside of the float component, the filter component can filter out the soil in the mixed liquid, obtain a relatively pure mixed liquid environment in the filtration space, and at the same time reduce the disturbance caused by the mixing of the mixed liquid, ensuring the relative stability of the float component in the filtration space. The sludge scraping mechanism can scrape off the mud and sand adhering to the outer surface of the filter component, thereby ensuring the filtration effect of the filter component.

[0037] IV. The chemical remediation treatment device for heavy metal pollution in soil of the present invention is equipped with a stirring catalytic device in the catalytic reaction tank, which realizes that the catalyst and the solution rotate in opposite directions, so that the catalyst can fully contact the solution, thereby improving the reaction efficiency of converting hexavalent chromium ions into trivalent chromium ions.

[0038] V. The chemical remediation treatment device for heavy metal pollution in soil of the present invention is equipped with a suspension chamber assembly on the stirring catalytic device, which can carry the catalyst and keep it suspended at a certain depth in the solution, ensuring that the catalyst is completely immersed in the solution. At the same time, by designing a multi-layered catalyst chamber and float structure, the coverage of the catalyst in the catalytic reaction tank is improved, and the suspension chamber assembly can rotate horizontally in the solution smoothly.

[0039] VI. The chemical remediation process for heavy metal pollution in soil of the present invention, when used in conjunction with the above-mentioned device, can efficiently remediate soil contaminated with heavy metals, reduce heavy metal ion pollution, and facilitate the subsequent resource-based reuse of heavy metals in the soil. Attached Figure Description

[0040] Figure 1 is a schematic diagram of the overall structure of the chemical remediation treatment device for heavy metal pollution in soil according to the present invention.

[0041] Figure 2 is a schematic diagram of the pickling tank and pickling progress monitoring device;

[0042] Figure 3 is the front view of Figure 2;

[0043] Figure 4 is a top view of Figure 2;

[0044] Figure 5 is a schematic diagram of the float assembly;

[0045] Figure 6 is an enlarged view of point A in Figure 5;

[0046] Figure 7 is an enlarged view of section B in Figure 2;

[0047] Figure 8 is an enlarged view of point C in Figure 2;

[0048] Figure 9 is a partial structural diagram of the second rack;

[0049] Figure 10 is a schematic diagram of the filter assembly and the sludge scraping mechanism;

[0050] Figure 11 is a structural schematic diagram of Figure 10 from another angle;

[0051] Figure 12 is an enlarged view of point D in Figure 11;

[0052] Figure 13 is an enlarged view of point E in Figure 11;

[0053] Figure 14 is a structural schematic diagram of the scraper blade and scraper connector;

[0054] Figure 15 is a schematic diagram of the catalytic reaction tank and the stirred catalytic device;

[0055] Figure 16 is a schematic diagram of the various mechanisms at the bottom of the catalytic reaction tank in Figure 15;

[0056] Figure 17 is a schematic diagram of the rotating mechanism and the driving mechanism;

[0057] Figure 18 is a structural schematic diagram from the lower side view of Figure 17;

[0058] Figure 19 is a structural schematic diagram from the upper side view of Figure 17;

[0059] Figure 20 is a structural schematic diagram of the suspension tank assembly;

[0060] Figure 21 is a partial schematic diagram of the catalyst chamber and float component in Figure 20;

[0061] Figure 22 is a schematic diagram of the connection between the suspended middle cylinder and the through shaft after the outer cylinder structure has been removed;

[0062] Figure 23 is a schematic diagram of the connection structure between the crossbeam at the top of the catalytic reaction tank and the through shaft;

[0063] Figure 24 is a schematic diagram of the measuring component.

[0064] In the attached diagram: 1. Pickling tank; 11. Soil inlet; 12. Feed hopper; 13. Washing net; 14. Pickling propeller; 15. Agitator motor; 16. Pickling liquid inlet; 17. Pickling liquid outlet; 18. First crossbeam; 181. Annular part; 182. Limiting ring; 19. Guide assembly; 191. Rolling support; 192. Rolling element; 2. Pickling progress monitoring device; 21. Float assembly; 211. Float body; 212. First rack; 213. Limiting rod; 214. Limiting boss; 22. Linkage assembly; 221. First rotating shaft; 222. First gear; 223. Second gear; 22 4. Second rack; 2241. Guide groove; 23. Observation assembly; 231. U-shaped tube; 2311. First pipe section; 2312. Second pipe section; 232. Piston tube; 233. Translational piston; 24. Filter assembly; 241. Filter frame; 242. Filter membrane; 243. Filter space; 244. L-shaped fixed column; 25. Sludge scraping mechanism; 251. Sludge scraper; 252. Sludge scraping transmission assembly; 2521. Third gear; 2522. Fourth gear; 2523. Sludge scraping rotating bearing; 2524. Sludge scraping ring; 253. Sludge scraping connecting assembly; 2531. Receiving ring; 2532. Receiving column ; 254. Sludge scraping drive component; 3. Catalytic reaction tank; 31. Solution inlet; 32. Solution outlet; 33. Bearing ring; 34. Bearing bearing; 35. First mounting shaft; 36. Second mounting shaft; 37. Support component; 38. Second crossbeam; 381. Positioning column; 382. Positioning bearing; 4. Stirring catalytic device; 41. Rotating mechanism; 411. Stirring collar; 412. Through shaft; 4121. Shaft body; 4122. Arc-shaped step; 413. Gear transmission assembly; 4131. First bearing; 4132. First external gear; 4133. Second external gear; 4134. First internal gear; 41 35. Second internal gear; 4136. Rotating ring; 4137. Positioning outer ring; 42. Drive mechanism; 421. Drive motor; 422. First drive gear; 423. Second drive gear; 43. Stirring assembly; 44. Suspension chamber assembly; 441. Catalyst chamber; 4411. Inner cavity; 4412. Liquid inlet; 442. Float component; 4421. Float tip; 443. Fixing rod; 444. Suspension cylinder; 4441. Outer cylinder; 4442. Inner disc; 4443. Through hole; 5. Measuring assembly; 51. Measuring tube; 52. Measuring tank; 53. Measuring valve; 6. Solid-liquid separation device. Detailed Implementation

[0065] The accompanying drawings are for illustrative purposes only and should not be construed as limiting this patent. To better illustrate this embodiment, some components in the drawings may be omitted, enlarged, or reduced, and do not represent the actual dimensions of the product. It is understandable to those skilled in the art that some well-known structures and their descriptions may be omitted in the drawings. The positional relationships described in the drawings are for illustrative purposes only and should not be construed as limiting this patent.

[0066] The technical solution of the present invention will be further described in detail below through specific embodiments and with reference to the accompanying drawings:

[0067] Example 1

[0068] Referring to Figure 1, this embodiment discloses a chemical remediation treatment device for soil heavy metal pollution, including an acid washing tank 1, an acid washing progress monitoring device 2, a solid-liquid separation device 6, a catalytic reaction tank 3, and a stirring catalytic device 4.

[0069] The pickling tank 1 is used for soil pickling. Soil and pickling solution are swirled in the pickling tank 1 to pickle all the heavy metals in the soil into the acidic mixed solution, thereby removing heavy metal pollution from the soil.

[0070] The acid washing progress monitoring device 2 is connected to the acid washing tank 1 and is used to monitor the soil acid washing progress in real time. By observing the acid washing progress monitoring device 2, information on the arrival of the soil acid washing endpoint can be obtained. Compared with the existing technology of repeatedly sampling experiments to monitor the acid washing progress, this embodiment can effectively improve the soil acid washing efficiency.

[0071] The inlet of the solid-liquid separation device 6 is connected to the acid washing tank for solid-liquid separation of the mixture obtained from soil acid washing. The liquid phase outlet of the solid-liquid separation device 6 is connected to the catalytic reaction tank 3. The catalytic reaction tank 3 is used to receive the solution obtained after solid-liquid separation and to carry out related reactions to reduce heavy metal pollution in the solution. The solid-liquid separation device 6 can be a solid-liquid separation compressor. The catalytic reaction tank 3 and the acid washing tank 1 are connected through the solid-liquid separation compressor and pipelines. After soil acid washing is completed, the solid-liquid separation compressor is started to perform solid-liquid separation, so that the separated solution enters the catalytic reaction tank 3.

[0072] The stirring catalytic device 4 is installed in the catalytic reaction tank 3 to drive the catalyst and solution to rotate in opposite directions in the electrochemical oxidation tank, thereby promoting full contact between the catalyst and solution for reaction and improving reaction efficiency.

[0073] In this embodiment, the acid washing progress monitoring device 2 can monitor the progress of soil acid washing in real time, eliminating the need for repeated sampling and experimental testing, thus improving the monitoring efficiency of soil acid washing. The stirring catalytic device 4 drives the solution and catalyst to rotate in opposite directions, ensuring sufficient contact between the catalyst and solution and improving reaction efficiency. The chemical remediation treatment device for heavy metal pollution in soil using this scheme can effectively improve soil remediation results and promote the resource utilization of heavy metals in the soil.

[0074] The structure of each part of this embodiment will be described in further detail below.

[0075] Referring to Figures 2 to 4, the upper end of the pickling tank 1 is roughly cylindrical, and the bottom of the pickling tank 1 is funnel-shaped with a cross-section that gradually decreases downwards. Three sets of pickling propellers 14 are installed on the inner wall of the pickling tank 1. Each pickling propeller 14 is connected to a stirring motor 15 for drive. The rotation axis of each pickling propeller 14 can be horizontal and does not pass through the vertical central axis of the pickling tank 1; that is, each pickling propeller 14 is horizontally lateral. From a top view, the rotation axes of each pickling propeller 14 can form an equilateral triangle in the pickling tank 1 by rotating clockwise or counterclockwise, which can better propel the water flow to rotate within the tank, performing swirling pickling of the soil and ensuring thorough mixing of the soil and pickling solution. A pickling solution inlet 16 is provided on the side wall of the pickling tank 1, through which the pickling solution is introduced into the pickling tank 1. A pickling liquid outlet 17 is provided at the bottom of the pickling tank 1 to discharge the mixed liquid after pickling.

[0076] Referring to Figures 2 to 4, a soil inlet 11 is provided on the side wall of the pickling tank 1. A feed hopper 12 is connected to the outside of the soil inlet 11, and a scouring net 13 is connected to the inside of the soil inlet 11. The feed hopper 12 may have a cross-sectional shape that gradually narrows from top to bottom. The top of the feed hopper 12 is open, and the bottom of the feed hopper 12 is connected to the soil inlet 11 on the side wall of the pickling tank 1. The scouring net 13 protrudes towards the interior of the pickling tank 1 to facilitate contact between the pickling solution and the soil. The bottom part of the feed hopper 12 can accommodate other debris in the soil.

[0077] During operation, soil contaminated with heavy metals is placed in the feed hopper 12. The acid solution in the pickling tank 1 continuously contacts and washes the soil through the holes in the rinsing mesh 13, ensuring the soil is evenly distributed in the pickling solution. Heavy metal elements in the soil dissolve into the pickling solution in an ionic state. The rinsing mesh 13 also screens the soil, breaking down and dissolving larger clods under the scouring action of the pickling solution. Hard stones, glass, or other debris in the soil are isolated at the bottom of the feed hopper 12. After the soil pickling process is complete, the debris at the bottom of the feed hopper 12 can be cleaned out.

[0078] Only after thorough acid leaching can heavy metal pollution in the soil be removed as much as possible, thus achieving the goal of soil remediation. In related technologies, there are methods to monitor the leaching progress by testing the composition of the acid leaching solution experimentally. However, this requires repeated sampling and experiments, and because it involves many types of heavy metals, it requires numerous experiments, resulting in low efficiency. But the inventors' research has found that during the soil heavy metal acid leaching process, the density of the acid leaching solution increases as heavy metals enter in ionic form. For example, at a concentration of 10% by mass, the density of a sulfuric acid solution is approximately 1.06 g / cm³. 3 The density of copper sulfate solution is approximately 1.08 g / cm³. 3 The density of cadmium sulfate solution is approximately 1.15 g / cm³. 3 The density of chromium sulfate solution is approximately 1.2 g / cm³. 3 Therefore, the progress of soil acid washing can be judged by the change in the density of the acid washing solution.

[0079] Referring to Figures 2 and 3, the acid washing progress monitoring device 2 of this embodiment is used to monitor the soil acid washing progress in the acid washing tank 1 in real time. It includes a float assembly 21, a linkage assembly 22 and an observation assembly 23. The float assembly 21 is floated in the acid washing tank 1. One end of the linkage assembly 22 is connected to the float assembly 21 for transmission, and the other end of the linkage assembly 22 is connected to the observation assembly 23 to drive the observation assembly 23 to change.

[0080] In this embodiment, as the acid washing process continues, heavy metal ions in the soil enter the mixed solution, causing the density of the solution to gradually increase. The float assembly 21 rises gradually as the density of the solution increases. This rise of the float assembly 21 drives the linkage assembly 22, which in turn causes the observation assembly 23 to change. By observing the changes in the observation assembly 23, the acid washing progress can be directly judged. When the liquid level in the observation assembly 23 stabilizes, it indicates that the density of the mixed solution has stabilized, meaning the acid washing of heavy metals in the soil has reached its endpoint.

[0081] Referring more specifically to Figures 5 and 6, the float assembly 21 includes a float body 211. A first crossbeam 18 is provided at the top of the pickling tank 1. The float body 211 is movably connected to the first crossbeam 18 in the vertical direction. A first rack 212 is fixedly connected to the float body 211 in the vertical direction for transmission connection with the linkage assembly 22. By movably connecting the float body 211 to the first crossbeam 18 in the vertical direction, the float body 211 can float stably in the pickling tank 1. The height change of the float body 211 is stably transmitted to the linkage assembly 22 for output through the vertically arranged first rack 212.

[0082] Referring to Figures 5 and 6, a first crossbeam 18 spans above the pickling tank 1, with both ends of the first crossbeam 18 fixedly connected to the pickling tank 1. An annular portion 181 is formed in the middle of the first crossbeam 18 to facilitate the installation of a float body 211. The float body 211 can be approximately conical in shape, hollow inside, with its tip pointing downwards. The float body 211 is located below the annular portion 181 in the middle of the first crossbeam 18. The taper of the float body 211 can be set relatively small, allowing it to float a longer distance when the density of the mixed solution changes, thus facilitating changes in the observation component 23 and making observation easier. A first rack 212 is fixedly connected to the top center of the float body 211, and the first rack 212 is vertically oriented. The first rack 212 can move with the up-and-down movement of the float body 211, thereby outputting to the linkage component 22.

[0083] To limit the horizontal position of the float body 211 and prevent the float assembly 21 from detaching from the first crossbeam 18, the float assembly 21 also includes limiting rods 213, and the first crossbeam 18 is provided with limiting rings 182. Multiple limiting rings 182 are arranged along the inner circle of the annular portion 181 of the first crossbeam 18. Multiple limiting rods 213 are vertically fixed to the top of the float body 211 and pass through the limiting rings 182. The top of each limiting rod 213 is provided with a limiting boss 214, the outer diameter of which is larger than the inner diameter of the limiting ring 182. The limiting rods 213 passing through the limiting rings 182 achieve a movable connection, allowing the float assembly 21 to float horizontally within a certain range. When the mixed liquid in the pickling tank 1 is discharged, the limiting bosses 214 support the float assembly 21, preventing it from detaching from the bottom when the pickling liquid is insufficient. Among them, multiple limit rods 213 are provided on the top of the float body 211 along the circumference, which can prevent the float body 211 from shifting in the horizontal direction and also prevent the float body 211 from rotating around the vertical axis.

[0084] Referring to Figures 5 to 7, the linkage assembly 22 includes a first rotating shaft 221, a first gear 222, a second gear 223, and a second rack 224. The first rotating shaft 221 is rotatably connected to the first crossbeam 18. One end of the first rotating shaft 221 is coaxially and fixedly connected to the first gear 222, and the other end of the first rotating shaft 221 is coaxially and fixedly connected to the second gear 223. The first gear 222 meshes with the first rack 212, and the second gear 223 meshes with the second rack 224. The second rack 224 is slidably connected to the first crossbeam 18, and one end of the second rack 224 is connected to the observation assembly 23. A bearing seat is provided on the first crossbeam 18, and the first rotating shaft 221 is rotatably connected to the bearing seat through the bearing.

[0085] During the entire transmission process, the float body 211 rises, causing the first rack 212 to move vertically. The first rack 212 drives the first gear 222 to rotate, which in turn drives the first shaft 221 to rotate. The first shaft 221 drives the second gear 223 to rotate, and the second gear 223 drives the second rack 224 to move. The second rack 224 causes the observation component 23 to change, so as to show the progress of soil acid washing.

[0086] Specifically, referring to the XYZ coordinate system shown in Figure 2, the first rack 212 is positioned along the Z-axis, the first rotating shaft 221 is positioned along the X-axis, and the second rack 224 is positioned along the Y-axis. Through the meshing of the first gear 222 and the first rack 212, the translational motion of the float body 211 along the Z-axis is converted into the rotation of the first rotating shaft 221 around the X-axis. Then, through the meshing of the second gear 223 and the second rack 224, the rotation around the X-axis is converted into the translational motion of the second rack 224 along the Y-axis.

[0087] Therefore, in this embodiment, the height change of the float body 211 in the Z direction is converted into the displacement change of the second rack 224 in the Y direction by the linkage component 22, so as to facilitate connection to the external observation component 23. Of course, the linkage component 22 provided in this embodiment is only one specific form, and those skilled in the art can also implement it through other transmission structures, which will not be elaborated here.

[0088] To more clearly display the height change of the float body 211, the diameter of the second gear 223 can be set to be larger than the diameter of the first gear 222. For example, if the diameter of the second gear 223 is six times that of the first gear 222, the linear velocity of the second gear 223 is also six times that of the first gear 222 when rotating by the same angle. This can magnify the upward distance of the float body 211, making it easier to drive the observation component 23 and observe the changes more readily.

[0089] Referring to Figures 7 to 9, a guide assembly 19 is fixedly connected to the first crossbeam 18. The guide assembly 19 includes a rolling support 191 and a rolling element 192. The rolling element 192 is rotatably connected to the rolling support 191 and can rotate along the length direction of the second rack 224. A guide groove 2241 is provided at the bottom of the second rack 224, and the second rack 224 abuts against the rolling element 192 through the guide groove 2241. In this embodiment, by setting the guide assembly 19, the second rack 224 can move on the rolling element 192. At the same time, the guide groove 2241 at the bottom of the second rack 224 serves as a limiting function to prevent the second rack 224 from deviating.

[0090] Specifically, the rolling support 191 is arranged along the length of the second rack 224, and the rolling element 192 can be formed by connecting a mounting shaft through a bearing. The inner ring of the bearing is fixedly connected to the mounting shaft, and both ends of the mounting shaft are fixedly connected to the rolling support 191. The outer ring of the bearing protrudes upwards and contacts the bottom of the second rack 224, providing support to the bottom of the second rack 224 and reducing resistance during its movement. A guide groove 2241 is also provided along the length of the bottom of the second rack 224. The width of the guide groove 2241 is slightly larger than the width of the bearing. The guide groove 2241 limits the movement of the second rack 224, allowing it to move along the rolling direction of the bearing without disengaging from the side.

[0091] Of course, the rolling support 191 and rolling element 192 shown in this embodiment are only one specific way to guide the second rack 224. Those skilled in the art can design other guiding structures to achieve the same result. For example, it can be achieved through a guide rail slider structure. When using a guide rail slider structure, the guide rail is fixedly connected to the first crossbeam 18 along the length direction of the second rack 224, and a slider is slidably connected to the guide rail. Multiple sliders can be provided. The top of the slider is fixedly connected to the bottom of the second rack 224, and the guide rail slider guides and limits the second rack 224.

[0092] Referring to Figures 5 and 10 to 14, the pickling progress monitoring device 2 also includes a filter assembly 24 and a sludge scraping mechanism 25. The filter assembly 24 is connected to the pickling tank 1 and forms a filtration space 243 in the pickling tank 1. The float assembly 21 is placed in the filtration space 243. The sludge scraping mechanism 25 is connected to the pickling tank 1 and moves in contact with the outer surface of the filter assembly 24. By forming a filtration space 243 in the pickling tank 1 through the filter assembly 24, soil in the mixed liquor can be filtered out, and a relatively pure mixed liquor environment can be obtained in the filtration space 243. On the other hand, it can reduce the disturbance caused by the mixing of the mixed liquor and ensure the relative stability of the float assembly 21 in the filtration space 243. The sludge scraping mechanism 25 can scrape off the mud and sand adhering to the outer surface of the filter assembly 24, thereby ensuring the filtration effect of the filter assembly 24.

[0093] Referring to Figure 5, the filter assembly 24 includes a filter frame 241 and a filter membrane 242. The filter frame 241 is fixedly connected to the first crossbeam 18. The filter membrane 242 covers the circumference and bottom of the filter frame 241 to form a filter space 243 in the pickling tank 1. The float assembly 21 is located in the filter space 243.

[0094] Specifically, the top of the filtration space 243 has an opening to allow the float assembly 21 to be placed inside from the top. The filtration space 243 is sealed and isolated around its perimeter and bottom by a filter membrane 242 to prevent sediment from entering the mixture. The internal dimensions of the filtration space 243 are larger than the dimensions of the float assembly 21, thus preventing direct contact between the float assembly 21 and the filter assembly 24, avoiding interference with the floating of the float body 211. The filtration space 243 formed inside the filter assembly 24 can be conical in shape, similar to the float body 211, but larger. This ensures effective floating of the float body 211 while reducing the volume of the mixture to be filtered.

[0095] Referring to Figures 10 to 14, the sludge scraping mechanism 25 includes a scraper blade 251, a scraper transmission assembly 252, a scraper connecting assembly 253, and a scraper drive component 254. The fixed end of the scraper drive component 254 is fixedly connected to the first crossbeam 18, and the output end of the scraper drive component 254 is connected to the scraper transmission assembly 252. The scraper transmission assembly 252 is connected to the scraper connecting assembly 253 to drive the scraper connecting assembly 253 to rotate around the filter assembly 24. The scraper connecting assembly 253 is fixedly connected to the scraper blade 251, and the scraper blade 251 is in contact with the filter membrane 242. The sludge scraping mechanism 25 can scrape away the mud and sand adhering to the outer surface of the filter membrane 242, thereby ensuring the filtration effect of the filter assembly 24.

[0096] Specifically, the scraper connection assembly 253 can be in a generally frame-like shape surrounding the outside of the filter assembly 24. For example, the scraper connection assembly 253 includes multiple receiving rings 2531 and receiving posts 2532. Individual receiving rings 2531 are arranged horizontally around the outside of the filter assembly 24, while different receiving rings 2531 are arranged vertically in sequence. The receiving rings 2531 are fixedly connected to each other via the receiving posts 2532, forming the frame structure of the scraper connection assembly 253. Multiple scraper blades 251 can be provided, each fixedly connected to a receiving ring 2531. For example, two scraper blades 251 can be arranged opposite each other on both sides of the filter assembly 24. The length direction of the scraper blades 251 is inclined vertically, so that one side of the scraper blade 251 fits against the outside of the filter assembly 24. The scraper drive component 254 can be a scraper motor, with its fixed end fixedly connected to the first crossbeam 18.

[0097] Referring to Figures 10 to 14, the sludge scraping drive assembly 252 includes a third gear 2521, a fourth gear 2522, a sludge scraping rotating bearing 2523, and a sludge scraping ring 2524. The sludge scraping rotating bearing 2523 is coaxially arranged with the filter assembly 24. The third gear 2521 is coaxially and fixedly connected to the output end of the sludge scraping drive component 254. The fourth gear 2522 is coaxially and fixedly connected to the outer ring of the sludge scraping rotating bearing 2523. The inner ring of the sludge scraping rotating bearing 2523 is fixedly connected to the first crossbeam 18. The sludge scraping ring 2524 is sleeved on the outer ring of the bearing, and the bottom of the sludge scraping ring 2524 is fixedly connected to the sludge scraping connection assembly 253. The sludge scraping drive component 254 drives the third gear 2521 to rotate, which in turn drives the fourth gear 2522 to rotate. The fourth gear 2522 drives the outer ring of the bearing to rotate, thereby causing the sludge scraping ring 2524 to drive the sludge scraping assembly to rotate around the filter assembly 24, scraping away the mud and sand adhering to the outer surface of the filter membrane 242.

[0098] In other embodiments, the scraper drive assembly 252 may also be connected using other transmission structures, as long as the output power of the scraper drive assembly can be transmitted to the scraper blade 251, which will not be elaborated here.

[0099] Referring to Figures 12 and 13, the upper end of the top support column 2532 is fixedly connected to the lower end of the scraper ring 2524 of the outer ring of the scraper rotating bearing 2523. The top of the filter frame 241 is fixedly connected to the bottom of the first crossbeam 18 through the L-shaped fixing column 244. The L-shaped fixing column 244 extends outward in a horizontal direction, so that the inner ring of the scraper rotating bearing 2523 can be mounted and fixed on the support of the L-shaped fixing column 244.

[0100] Referring to Figures 7 and 8, the observation assembly 23 includes a U-shaped tube 231, a piston tube 232, and a translational piston 233. The U-shaped tube 231 is fixedly connected to the outer wall of the acid washing tank 1 and contains liquid. One end of the U-shaped tube 231 is connected to the piston tube 232. The translational piston 233 is fixedly connected to the linkage assembly 22 and slidably connected within the piston tube 232. By pushing the translational piston 233 within the piston tube 232 through the linkage assembly 22, the liquid level at one end of the U-shaped tube 231 changes, thus allowing for direct observation of the soil acid washing progress.

[0101] Specifically, the U-shaped tube 231 and the piston tube 232 can be integrally formed, or they can be connected through an intermediate pipe, as long as the piston tube 232 and one end of the U-shaped tube 231 are sealed and connected. The piston tube 232 includes at least one section that is collinear with the second rack 224, allowing the second rack 224 to push the translational piston 233 within the piston tube 232. The U-shaped tube 231 is fixedly connected to the outer side wall of the pickling tank 1 via a pipe clamp. The U-shaped tube 231 contains a colored, non-volatile liquid, and graduations are provided on the side wall of the U-shaped tube 231 for easy observation.

[0102] To make the changes in liquid level in the U-shaped tube 231 more noticeable, the side connecting the U-shaped tube 231 to the piston tube 232 can be designated as the first tube segment 2311, and the other side as the second tube segment 2312. The diameter of the first tube segment 2311 is larger than the diameter of the second tube segment 2312. For example, if the diameter of the first tube segment 2311 is twice the diameter of the second tube segment 2312, then the cross-sectional area of ​​the first tube segment 2311 is four times that of the second tube segment 2312. This would magnify the changes in liquid level by four times, making them easier to observe.

[0103] In other embodiments, the observation component 23 may be displayed in other ways. For example, the observation component 23 may be implemented by connecting the block to the end of the second rack 224 via a traction rope, the traction rope passing through a pulley system to change its direction of movement, and displaying the change in the height of the block.

[0104] It is understandable that the acid washing progress and the changes in observation component 23 do not necessarily have to be linear; as long as there is a positive correlation between the two, the acid washing progress can be determined. When observation component 23 stabilizes, and there is sufficient acid washing solution, it can be determined that the soil acid washing has reached its end.

[0105] After the soil acid washing is completed, the mixture in acid washing tank 1 is subjected to solid-liquid separation to obtain the remediated soil and the heavy metal ion contaminated solution. The heavy metal ion contaminated solution needs to be reacted to reduce the heavy metal ion contamination in the solution. The reaction is carried out in catalytic reaction tank 3.

[0106] Referring to Figure 15, the catalytic reaction tank 3 is roughly cylindrical, with a solution inlet 31 and a solution outlet 32 ​​on its bottom sides, respectively. The solution obtained from acid washing and solid-liquid separation is fed into the reaction tank through the solution inlet 31, thereby reducing heavy metal ion pollution in the solution. The fully reacted solution is discharged through the solution outlet 32. The soil in the acid washing tank 1 is acid-washed to obtain a mixed solution. After solid-liquid separation, the solution containing heavy metal ions is fed into the catalytic reaction tank 3 through the solution inlet 31.

[0107] Referring to Figure 24, a measuring component 5 is connected to the outer wall of the catalytic reaction tank 3. The measuring component 5 includes a measuring tube 51, a measuring tank 52, and a measuring valve 53. The measuring tube 51 is located on the lower side wall of the catalytic reaction tank 3 and communicates with the interior of the catalytic reaction tank 3. The other end of the measuring tube 51 is provided with the measuring tank 52, which is fixedly connected to the side wall of the catalytic reaction tank 3. The measuring valve 53 is connected to the measuring tube 51. By opening the measuring valve 53, the liquid in the catalytic reaction tank 3 can be placed into the measuring tank 52, allowing for sampling of the liquid in the catalytic reaction tank 3 to monitor the reaction progress in the catalytic reaction tank 3.

[0108] Referring to Figure 15, a stirring catalytic device 4 is provided in the catalytic reaction tank 3 to promote sufficient contact between the solution and the catalyst, thereby promoting the reaction in the catalytic reaction tank 3. The stirring catalytic device 4 includes a rotating mechanism 41, a driving mechanism 42, a stirring assembly 43, and a suspension chamber assembly 44. The rotating mechanism 41 is disposed in the catalytic reaction tank 3. The stirring assembly 43 and the suspension chamber assembly 44 are both connected to the rotating mechanism 41. The driving mechanism 42 is connected to the rotating mechanism 41 to drive the stirring assembly 43 and the suspension chamber assembly 44 to rotate in opposite directions simultaneously.

[0109] The following is a detailed explanation of the suspension reaction device.

[0110] Referring to Figure 15, the suspended reaction device is installed in the catalytic reaction tank 3. Taking the illustrated direction as an example, the rotating mechanism 41 is vertically distributed throughout the entire height space of the catalytic reaction tank 3. The drive mechanism 42 is connected to the bottom outside of the catalytic reaction tank 3 and passes through the bottom of the catalytic reaction tank 3, and is driven by the rotating mechanism 41. The lower end of the rotating mechanism 41 is connected to the stirring assembly 43, which can agitate the solution in the catalytic reaction tank 3 to form a swirling flow. Above the stirring assembly 43 and vertically connected to the rotating mechanism 41 is the suspension chamber assembly 44. The suspension chamber assembly 44 can carry the catalyst required for the reaction and floats with the change of liquid level in the catalytic reaction tank 3, ensuring that the catalyst can always be in contact with the solution to promote the reaction. The rotating mechanism 41 can make the suspension chamber assembly 44 and the stirring assembly 43 rotate in opposite directions, thereby promoting the contact between the catalyst and the solution, and enabling the heavy metal ions to fully react and transform. The specific structure of the rotating mechanism 41 will be further explained below.

[0111] Referring to Figures 15 to 19, the rotating mechanism 41 includes a stirring ring 411, a through shaft 412, and a gear transmission assembly 413. The stirring ring 411 and the through shaft 412 are respectively connected to the gear transmission assembly 413 for transmission. The gear transmission assembly 413 achieves opposite rotation directions for the stirring ring 411 and the through shaft 412 through a series of gear transmissions.

[0112] Specifically, the stirring ring 411 is a hollow column and is rotatably connected to the bottom of the catalytic reaction tank 3. A support ring 33 extends upward from the bottom of the catalytic reaction tank 3, and a support bearing 34 is fixedly sleeved on the outside of the support ring 33. The stirring ring 411 is fixedly sleeved on the outer ring of the support bearing 34, thereby realizing the rotatable connection between the stirring ring 411 and the bottom of the catalytic reaction tank 3.

[0113] Referring to Figures 17 to 19, the gear transmission assembly 413 includes a first bearing 4131, a first external gear 4132, a second external gear 4133, a first internal gear 4134, and a second internal gear 4135. The first external gear 4132 and the second external gear 4133 are rotatably connected to the catalytic reaction tank 3. The first internal gear 4134 is coaxially fixedly connected to the inner side of the upper end of the stirring ring 411. The first external gear 4132 is located in the stirring ring 411 and meshes with the first internal gear 4134. The second external gear 4133 meshes with the first external gear 4132. The outer ring of the first bearing 4131 is fixedly connected to the catalytic reaction tank 3. The inner ring of the first bearing 4131 is coaxially fixedly connected to the second internal gear 4135. The second internal gear 4135 meshes with the second external gear 4133. The bottom end of the through shaft 412 is fixedly connected to the second internal gear 4135.

[0114] Referring to Figures 17 and 18, the top of the support ring 33 is provided with a first mounting shaft 35, a second mounting shaft 36, and a support member 37. A first external gear 4132 is rotatably connected to the first mounting shaft 35, and a second external gear 4133 is rotatably mounted on the second mounting shaft 36. A positioning outer ring 4137 is fitted around the outer ring of the first bearing 4131, and the top end of the support member 37 is fixedly connected to the positioning outer ring 4137. Both the first mounting shaft 35 and the second mounting shaft 36 are arranged vertically. The first mounting shaft 35 is fixedly connected to the top end face of the support ring 33, and the projection of the second mounting shaft 36 on the horizontal plane is located inside the support ring 33 and is fixedly connected to the bottom wall of the catalytic reaction tank 3. The first external gear 4132 and the second external gear 4133 can be rotatably connected to the upper ends of the first mounting shaft 35 and the second mounting shaft 36 respectively via bearings. The first mounting shaft 35 and the second mounting shaft 36 provide axial support for the first external gear 4132 and the second external gear 4133. The first mounting shaft 35 and the second mounting shaft 36 are both located in the stirring ring 411, making the structure more compact.

[0115] It is understandable that when a pair of external gears mesh, their respective shafts rotate in opposite directions; when a pair of internal gears mesh, their respective shafts rotate in the same direction. In this embodiment, the stirring ring 411 drives the through shaft 412, and the meshing relationships of the gears are as follows: the first internal gear 4134 meshes with the first external gear 4132, the first external gear 4132 meshes with the second external gear 4133, and the second external gear 4133 meshes with the second internal gear 4135. Therefore, the entire transmission path includes one pair of external gears meshing and two pairs of internal and external gears meshing. Since the meshing of internal and external gears does not change the rotation direction of the shaft, while the meshing of external gears changes the rotation direction of the shaft, the above transmission relationship allows the stirring ring 411 and the through shaft 412 to rotate in opposite directions.

[0116] By selecting an appropriate transmission ratio, the stirring ring 411 and the through shaft 412 can generate different rotational speeds. For example, in this embodiment, since the linear velocity of the gears at each meshing point is the same, but the diameter of the second internal gear 4135 is larger than that of the first internal gear 4134, the angular velocity of the second internal gear 4135 is smaller than that of the first internal gear 4134. That is, if the second internal gear 4135 rotates once, the first internal gear 4134 will rotate more than once, making the rotational speed of the stirring assembly 43 greater than that of the catalyst chamber 441, promoting the contact between the catalyst and the liquid, and improving the efficiency of converting hexavalent chromium ions into trivalent chromium ions.

[0117] Referring to Figures 17 to 19, the first internal gear 4134 is fixedly connected to the inner side of the upper end of the stirring ring 411. The projection of the first external gear 4132 on the horizontal plane is located inside the stirring ring 411, thus enabling it to mesh with the first internal gear 4134. The vertical height of the first external gear 4132 is higher than that of the first internal gear 4134, allowing the lower end of the first external gear 4132 to mesh with the first internal gear 4134, while the upper end of the first external gear 4132 extends above the stirring ring 411. The projection of the axis of the second external gear 4133 on the horizontal plane is located inside the stirring ring 411, resulting in a compact structure, and the second external gear 4133 meshes with the upper end of the first external gear 4132. The second internal gear 4135 meshes with the second external gear 4133, so the second external gear 4133 can drive the second internal gear 4135 to rotate. The second internal gear 4135 is fixedly connected to the inner ring of the first bearing 4131, thereby driving the inner ring of the first bearing 4131 to rotate. The outer ring of the first bearing 4131 is fixedly connected to the top of the support ring 33 at the bottom of the catalytic reaction tank 3, which can be connected through an intermediate connecting part, so that the first bearing 4131 can be supported above the stirring ring 411.

[0118] Referring to Figure 18, the inner ring of the first bearing 4131 and the second internal gear 4135 can be connected by an intermediate part, such as a rotating ring 4136. The bottom end of the through shaft 412 can also be indirectly fixedly connected to the second internal gear 4135 via the rotating ring 4136.

[0119] The advantage of the gear transmission assembly 413 used in this embodiment is that the central axes of the through shaft 412 and the stirring ring 411 are the same, that is, the rotation centers of the through shaft 412 and the stirring ring 411 are the same. Therefore, the rotation center of the stirring assembly 43 is the same as the rotation center of the suspension chamber assembly 44. Both can be located at the center of the cylindrical catalytic reaction tank 3, which can more fully cover the catalytic reaction tank 3 compared to an eccentric arrangement, promoting solution stirring and catalyst contact reaction. At the same time, this embodiment only requires one drive mechanism 42 to drive two opposite rotational motions, while the prior art usually requires two drive mechanisms 42 to drive them separately. For the bearings used in this embodiment, if axial loads need to be borne, bearings capable of bearing axial loads can be selected, such as cylindrical roller bearings, which can provide axial support.

[0120] Referring to Figures 15, 17 and 22, the through shaft 412 includes a plurality of shafts 4121 distributed circumferentially along the second internal gear 4135. The bottom of each shaft 4121 is fixedly connected to the second internal gear 4135. The suspension chamber assembly 44 has a plurality of through holes 4443 vertically. Each shaft 4121 passes through the through holes 4443 and is movably connected to the suspension chamber assembly 44.

[0121] In this embodiment, the shaft 4121 can be bent from bottom to top. For example, the bottom of the shaft 4121 is fixedly connected to the second internal gear 4135 via a rotating ring 4136. Each shaft 4121 forms an inwardly converging bent structure from the bottom up. After converging, the shafts 4121 extend vertically upward, making the structure more compact. The number of shafts 4121 can be selected according to actual needs, ensuring that the suspension chamber assembly 44 has both rotation and floating functions. For example, in this embodiment, three shafts 4121 are used. Three or more shafts 4121 can ensure, to a certain extent, that the suspension chamber assembly 44 remains horizontally stable during vertical floating, thereby ensuring the continuous and stable chemical reaction of hexavalent chromium ions converting to trivalent chromium ions. By connecting multiple shafts 4121 through the through-hole 4443 of the suspension chamber assembly 44, the suspension chamber assembly 44 can both float stably vertically and rotate together with the through shaft 412. Since the suspended chamber assembly 44 is vertically connected, it can remain suspended in the liquid as the liquid level in the catalytic reaction tank 3 changes, ensuring that the catalyst in the suspended chamber assembly 44 is always in contact with the liquid and can effectively carry out the catalytic reaction.

[0122] Referring to Figures 15 and 23, a second crossbeam 38 is fixedly connected to the top of the catalytic reaction tank 3. A positioning post 381 extends downwards from the bottom of the second crossbeam 38, and a positioning bearing 382 is sleeved on the positioning post 381. The outer ring of the positioning bearing 382 is fixedly connected to the top of each shaft 4121. The positioning bearing 382 positions each shaft 4121, forming a stable through-shaft 412 structure. The top of each shaft 4121 has an arc-shaped step 4122 that matches the outer ring of the positioning bearing 382 for fixed connection.

[0123] Referring to Figures 20 to 22, the suspension chamber assembly 44 is described in detail below. The suspension chamber assembly 44 carries a catalyst that comes into contact with the solution, thereby promoting the reaction. The suspension chamber assembly 44 includes a catalyst chamber 441, a float 442, a retaining rod 443, and a suspension cylinder 444. The retaining rod 443 is fixedly connected to the suspension cylinder 444 and extends circumferentially. The catalyst chamber 441 and the float 442 are both annular and surround the outside of the suspension cylinder 444, and are respectively fixedly connected to the retaining rod 443. The suspension chamber assembly 44 is movably connected vertically to a rotating mechanism 41 and rotates with the rotating mechanism 41. The rotating mechanism 41 has multiple vertically arranged shafts 4121, each rotating around the same vertical axis. The suspension chamber assembly 44 has multiple vertically formed through holes 4443, and each shaft 4121 passes through each through hole 4443 for movable connection.

[0124] In this embodiment, buoyancy is provided by the float 442, and the catalyst chamber 441 and the float 442 are connected to the suspension cylinder 444 by the fixing rod 443. Since the suspension chamber assembly 44 is movably connected to the rotating mechanism 41 in a vertical direction, it can always be suspended in the solution as the liquid level changes, so that the catalyst in the suspension chamber assembly 44 can always be in contact with the solution. At the same time, the suspension chamber assembly 44 can rotate with the rotating mechanism 41, which promotes further contact between the solution and the catalyst, and effectively carries out the catalytic reaction.

[0125] Specifically, the catalyst chamber 441 can be approximately annular, with an inner cavity 4411 for containing the catalyst. The catalyst can be a micro-electrolysis catalyst made by mixing iron and carbon, utilizing the galvanic cell effect formed between iron and carbon to reduce hexavalent chromium. A liquid inlet 4412 communicating with the inner cavity 4411 is provided on the side wall of the catalyst chamber 441, allowing liquid to enter the inner cavity 4411 and contact the catalyst. The float 442 can also be approximately annular, or formed by combining multiple arc shapes to form an annulus. Multiple catalyst chambers 441 and floats 442 can be provided, with different diameters and alternating radially, so that each catalyst chamber 441 and each float 442 is spaced apart around the circumference of the suspension cylinder 444, providing better and more balanced buoyancy to the suspension chamber assembly 44. When the float 442 is annular, float tips 4421 can be provided at both ends of the annulus to reduce liquid resistance during rotation. The catalyst in the suspension chamber assembly 44 is always in contact with the liquid, thereby effectively promoting the chemical reaction of hexavalent chromium to trivalent chromium.

[0126] Example 2

[0127] Referring to Figure 20, this embodiment is similar to Embodiment 1, except that in this embodiment, the float component 442 includes an inner float and an outer float, and the catalyst chamber 441 includes a first chamber, a second chamber, and a third chamber. They are arranged from the inside out as follows: first chamber, inner float, second chamber, third chamber, and outer float. By setting an appropriate buoyancy, the suspended chamber assembly 44 can always be kept in the liquid, allowing it to fully contact the liquid in the catalytic reaction tank 3 and undergo a chemical reaction.

[0128] Referring to Figures 20 and 22, the floating inner cylinder includes an outer cylinder 4441 and an inner disc 4442. The outer cylinder 4441 is vertically continuous, and the inner disc 4442 has multiple vertically formed through holes 4443 and is fixedly connected to the outer cylinder 4441. Each retaining rod 443 is fixedly connected to the outside of the outer cylinder 4441, and each shaft 4121 is movably connected through the through holes 4443 of the inner disc 4442.

[0129] Referring to Figure 22, one side surface of the retaining rod 443 is fixedly connected to the catalyst chamber 441 and the float component 442, while the other side surface of the retaining rod 443 is streamlined. This streamlined design reduces resistance to contact with the liquid. For example, retaining rods 443 are fixedly connected to both the upper and lower sides of the catalyst chamber 441 and the float component 442. The bottom of the upper retaining rod 443 is fixedly connected to the catalyst chamber 441 and the float component 442, and its top is streamlined. The top of the lower retaining rod 443 is fixedly connected to the catalyst chamber 441 and the float component 442, and its bottom is streamlined.

[0130] Example 3

[0131] This embodiment provides a chemical remediation process for soil heavy metal pollution, used in conjunction with the apparatus shown in Figures 1 to 24, and includes the following steps:

[0132] S1: Soil contaminated with heavy metals is acid-washed in acid washing tank 1;

[0133] S2: Observe the soil acid washing progress in acid washing tank 1 in real time through acid washing progress monitoring device 2 until soil acid washing is completed;

[0134] S3: The mixture obtained after acid washing is separated into solid and liquid components by the solid-liquid separation device 6;

[0135] S4: The solution obtained after solid-liquid separation is sent into the catalytic reaction tank 3. The solution and the catalyst are rotated in opposite directions by the stirring catalytic device 4 to promote the reaction and reduce heavy metal pollution.

[0136] In step S1, the soil contaminated with heavy metals is placed into the feed hopper 12 of the pickling tank 1. The mixed liquid in the pickling tank 1 comes into contact with the soil through the holes on the washing net 13 and washes it, so that the soil is evenly spread in the pickling liquid. The heavy metal elements in the soil dissolve into the pickling liquid in an ionic state, and hard stones, glass and other debris are isolated at the bottom of the feed hopper 12.

[0137] In step S1, the pickling propeller 14 on the inner wall of the pickling tank 1 is used to drive the pickling liquid to rotate and generate a swirling flow, which improves the washing effect of the pickling liquid on the soil and the uniform diffusion effect of the soil in the pickling liquid.

[0138] In step S2, the float assembly 21 of the pickling progress monitoring device 2 floats up and down as the density of the mixed liquor in the pickling tank 1 changes. The float assembly 21 drives the observation assembly 23 to change through the linkage assembly 22, so that the pickling endpoint can be judged intuitively without the need to sample the mixed liquor.

[0139] In step S3, the acid-washed mixture and soil are separated by the solid-liquid separation device 6 to obtain the remediated soil and the solution containing heavy metal ion pollution. The solution containing heavy metal ion pollution is sent to the electrochemical oxidation tank for catalytic reaction.

[0140] In step S4, the stirring catalytic device 4 has a stirring component 43 and a suspension chamber component 44 rotating in opposite directions. The stirring component 43 can stir the solution in the catalytic reaction tank 3 to form a swirling flow, and the suspension chamber component 44 carries the catalyst, so that the solution and the catalyst rotate in opposite directions to promote the reaction and reduce heavy metal pollution in the soil.

[0141] In step S4, the suspension chamber assembly 44 of the stirring catalytic device 4 is suspended in the solution. During the process of adding the solution to the catalytic reaction tank 3, the suspension chamber assembly 44 can float up as the liquid level in the catalytic reaction tank 3 rises, and the catalyst and the solution can always be in full contact.

[0142] After step S4, recyclable heavy metal resources in the solution are recovered and reused. For example, hexavalent chromium is reduced to trivalent chromium, and then the pH value is increased to form Cr(OH)3 precipitate for recovery and reuse.

[0143] In the chemical remediation process for heavy metal pollution in soil according to this embodiment, the acid washing endpoint can be determined without sampling the acid washing mixture, thus effectively improving the soil acid washing efficiency. The suspended catalytic stirring reactor promotes sufficient contact between the solution and the catalyst, thereby increasing the conversion rate of heavy metal ions and facilitating the resource utilization of heavy metals in the soil. For example, it can reduce hexavalent chromium to trivalent chromium, reducing hexavalent chromium ion heavy metal pollution and recovering trivalent chromium metal resources.

[0144] The above embodiments are merely illustrative examples. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of this invention should be included within the scope of protection of the claims of this invention.

Claims

1. A chemical remediation treatment device for soil heavy metal pollution, characterized in that: The system includes an acid washing tank (1) for soil acid washing; an acid washing progress monitoring device (2) connected to the acid washing tank (1) for real-time monitoring of soil acid washing progress; a solid-liquid separation device (6) connected to the acid washing tank (1) for solid-liquid separation of the mixed liquid obtained from soil acid washing; a catalytic reaction tank (3) connected to the liquid phase outlet of the solid-liquid separation device (6) for receiving the solution obtained after solid-liquid separation and reacting it to reduce heavy metal pollution in the solution; and a stirring catalytic device (4). The device (4) is set in the catalytic reaction tank (3) to drive the catalyst and solution to rotate in opposite directions in the electrochemical oxidation tank; the pickling progress monitoring device (2) includes a float assembly (21), a linkage assembly (22) and an observation assembly (23). The float assembly (21) is floated in the pickling tank (1). One end of the linkage assembly (22) is connected to the float assembly (21) for transmission, and the other end of the linkage assembly (22) is connected to the observation assembly (23) to drive the observation assembly (23) to change; the pickling progress monitoring device (2) also includes a filter assembly (24) and a sludge scraping mechanism (25). The component (24) is connected to the pickling tank (1) and forms a filtration space (243) in the pickling tank (1). The float assembly (21) is placed in the filtration space (243). The sludge scraping mechanism (25) is connected to the pickling tank (1) and moves in contact with the outer surface of the filter assembly (24). The observation assembly (23) includes a U-shaped tube (231), a piston tube (232), and a translational piston (233). The U-shaped tube (231) is fixedly connected to the outer wall of the pickling tank (1) and contains liquid. One end of the U-shaped tube (231) is connected to the piston tube (232), and the translational piston (233) is connected to the outer wall of the pickling tank (1). The linkage component (22) is fixedly connected and slidably connected in the piston tube (232); the stirring catalytic device (4) includes a rotating mechanism (41), a driving mechanism (42), a stirring component (43), and a suspension chamber component (44). The rotating mechanism (41) is disposed in the catalytic reaction tank (3). The stirring component (43) and the suspension chamber component (44) are respectively connected to the rotating mechanism (41). The suspension chamber component (44) is used to carry the catalyst. The driving mechanism (42) is connected to the rotating mechanism (41) to drive the stirring component (43) and the suspension chamber component (44) to rotate in opposite directions simultaneously.The suspension chamber assembly (44) includes a catalyst chamber (441), a float (442), a retaining rod (443), and a suspension cylinder (444). The retaining rod (443) is fixedly connected to the suspension cylinder (444) and extends circumferentially. The catalyst chamber (441) and the float (442) are both annular and surround the outside of the suspension cylinder (444), and are respectively fixedly connected to the retaining rod (443). The suspension chamber assembly (44) is vertically connected to the rotating machine. The structure (41) is movably connected and rotates with the rotating mechanism (41); the catalyst chamber (441) has an inner cavity (4411) for containing the catalyst, and the side wall of the catalyst chamber (441) has a liquid inlet (4412) communicating with the inner cavity (4411). Multiple catalyst chambers (441) and multiple floats (442) are provided, and each catalyst chamber (441) and each float (442) is spaced apart around the circumference of the suspension cylinder (444).

2. The chemical remediation treatment device for heavy metal pollution in soil according to claim 1, characterized in that: The rotating mechanism (41) includes a plurality of vertically arranged shafts (4121), each shaft (4121) rotating around the same vertical axis. The suspension chamber assembly (44) has a plurality of vertically arranged through holes (4443), and each shaft (4121) is movably connected through each of the through holes (4443).

3. The chemical remediation treatment device for heavy metal pollution in soil according to claim 2, characterized in that: The pickling tank (1) has a soil inlet (11) on its side wall. A feed hopper (12) is connected to the outside of the soil inlet (11), and a scouring net (13) is connected to the inside of the soil inlet (11).

4. A chemical remediation process for soil heavy metal pollution, employing the apparatus described in any one of claims 1-3, characterized in that: Includes the following steps: S1: Soil contaminated with heavy metals is acid-washed in acid washing tank (1); S2: The soil acid washing progress in the acid washing tank (1) is observed in real time through the acid washing progress monitoring device (2) until the soil acid washing is completed; S3: The mixture obtained after acid washing is separated into solid and liquid by the solid-liquid separation device (6); S4: The solution obtained after solid-liquid separation is sent into the catalytic reaction tank (3), and the solution and catalyst are rotated in opposite directions by the stirring catalytic device (4) to promote the chemical reaction of heavy metal ions and reduce heavy metal pollution.

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