Soil treatment process

Abstract

The present invention discloses a soil treatment process, comprising the following steps: ① placing soil in a first reaction tank, into which an EDTA aqueous solution is introduced, where heavy metal ions in the soil react with the EDTA to form an EDTA-heavy metal complex; ② stirring the soil and the EDTA aqueous solution, and then draining the soil and the EDTA aqueous solution into a filtration tank; ③ draining the EDTA aqueous solution from the filtration tank into a liquid accumulation tank; ④ introducing a sodium sulfide solution into the liquid accumulation tank, where the sodium sulfide reacts with the EDTA-heavy metal complex to form a heavy metal sulfide precipitate, and the EDTA is separated from the heavy metal ions; ⑤ introducing the reactants from the liquid accumulation tank into a container tank, where the container tank separates the heavy metal sulfide precipitate from the liquid by filtration; ⑥ introducing the liquid from step ⑤ into a second reaction tank, where hydrochloric acid and hydrogen peroxide are added to the second reaction tank to remove excess sodium sulfide by reaction; and ⑦ introducing the EDTA aqueous solution from the second reaction tank into the first reaction tank via a pipeline. The present invention provides a soil treatment process that recycles and reuses the EDTA solution, thereby reducing process costs.

Description

Technical Field

[0001] The present invention relates to the technical field of soil regeneration, and more particularly to a soil treatment process. Background Art

[0002] Heavy metal contamination of soil is becoming increasingly serious. One soil treatment process involves using EDTA solution to react with heavy metal ions in the soil to separate them from the soil, improving the soil and enabling soil recycling. However, the complexes produced by the EDTA reaction with heavy metal ions in the soil are prone to secondary pollution. Furthermore, EDTA is expensive, and direct disposal increases overall process costs, necessitating improvements. Summary of the Invention

[0003] The purpose of the present invention is to overcome the deficiencies of the prior art and provide a soil treatment process that recycles and reuses EDTA solution and reduces process costs.

[0004] To achieve the above-mentioned object, the present invention adopts the following technical solution: a soil treatment process, comprising the following treatment steps: ① placing soil in a first reaction tank, introducing an EDTA aqueous solution into the first reaction tank, and causing heavy metal ions in the soil to react with the EDTA to form an EDTA heavy metal complex; ② after stirring the soil and the EDTA aqueous solution, the soil and the EDTA aqueous solution are discharged together into a filter tank; ③ the EDTA aqueous solution is discharged from the filter tank into a liquid accumulation tank; ④ a sodium sulfide solution is introduced into the liquid accumulation tank, causing the sodium sulfide to react with the EDTA heavy metal complex to form a precipitate of heavy metal sulfide, and the EDTA is separated from the heavy metal ions; ⑤ the reactants in the liquid accumulation tank are introduced into a container tank, and the container tank separates the heavy metal sulfide precipitate from the liquid by filtration; ⑥ the liquid in step ⑤ is introduced into a second reaction tank, and hydrochloric acid and hydrogen peroxide are added to the second reaction tank to react and remove excess sodium sulfide; and ⑦ the DETA aqueous solution in the second reaction tank is introduced into the first reaction tank through a pipeline.

[0005] The present invention is further configured such that the soil in step ① is crushed by a crushing device to crush the gravel in the soil, and then enters the reaction tank 1.

[0006] The present invention is further configured such that the reaction tank 1 is equipped with a driving device 1 and a driving device 2, and both the driving device 1 and the driving device 2 are equipped with a stirring rod, and the stirring rod extends into the reaction tank 1.

[0007] The present invention is further configured as follows: the container tank is installed with a sleeve, the sleeve includes a channel one and a channel two located below the channel one, the channel one is installed with a filter component, the filter component is inserted into the channel one, and a liquid outlet is provided at the bottom of the channel one and is connected to a valve body three; a pressure plate is installed on the top of the filter component, the lower end of the pressure plate is fit with the upper end surface of the filter component, the pressure plate is installed with a rod sleeve, the rod sleeve passes through the filter component, the rod sleeve is installed with a gasket, and the gasket is inserted into the rod sleeve; the sleeve is installed with a rod body, the rod body can move up and down along the axial direction, the outer wall of the rod body is provided with a protrusion, the protrusion can pass through the gasket, and the outer diameter of the protrusion is larger than the inner diameter of the gasket; the channel two is slidably connected and installed with a piston plate, which closes the upper end of the channel two when the piston plate is at the upper end limit position to disconnect the channel two from the channel one, the piston plate is provided with a through hole one, and the minimum distance between the through hole one and the axis of the piston plate is larger than the inner diameter of the channel one; the rod body is installed with a baffle, which is located above the piston plate.

[0008] The present invention is further configured such that the washer and the rod body are coaxially arranged.

[0009] The present invention is further configured such that a connecting disk is connected to the bottom of the piston plate, the connecting disk is provided with a groove body and a second through hole, the groove body is connected to the second through hole, the second through hole is connected to a hose, and the first through hole is connected to the groove body.

[0010] The present invention is further configured such that a plurality of through holes are provided along the circumference of the piston plate, and the groove body is in the shape of a circular ring.

[0011] The present invention is further configured such that the first hole is a tapered hole.

[0012] The present invention is further configured such that a discharge port is provided on one side of the container tank, and a push plate is installed on the other side of the container tank. The push plate can be close to or away from the discharge port, and the bottom position of the push plate is at the same height as the top position of the pressure plate.

[0013] In summary, the present invention has the following beneficial effects:

[0014] 1. Sodium sulfide reacts with EDTA heavy metal complex to generate heavy metal sulfide precipitation, heavy metals and EDTA are separated, and EDTA is released and then recycled, reducing the cost of EDTA solution.

[0015] 2. By spraying the soil multiple times, the heavy metals remaining in the soil continue to react with the EDTA solution, reducing the heavy metal content in the soil and the EDTA residue in the soil, resulting in better soil regeneration. The liquid obtained from the initial filtration is treated separately from the liquid obtained from the spray filtration to ensure the concentration of the reused EDTA solution, eliminating the concentration purification process step and reducing process costs. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 Schematic diagram of the process equipment of the embodiment;

[0017] Figure 2 is a cross-sectional view of a container tank in an embodiment;

[0018] Figure 3 for Figure 2 Enlarged view of point A in the middle;

[0019] Figure 4 for Figure 2 Enlarged view of point B in the middle;

[0020] Figure 5 2 is a cross-sectional view of the connection disk in the embodiment.

[0021] Figure numerals: feed bin 1, crushing device 11, reaction tank 12, drive device 121, drive device 2 122, valve body 13, filter tank 14, liquid accumulation tank 15, liquid inlet 151, pipeline 16, fluid pump 161, container tank 2, cavity 21, discharge port 211, baffle 212, push plate 213, valve body 22, sleeve 3, channel 1 31, channel 2 32, fixing plate 1 33, spring 34, filter component 4, rod body 5, drive component 51, rod sleeve 52, insert cylinder 521, gasket 522, boss 523, pressure plate 53, fixing ring 54, fixing plate 2 55, protrusion 56, baffle 57, valve body 3 6, piston plate 7, through hole 1 71, connecting plate 72, trough body 721, through hole 2 722, hose 73, reaction tank 2 8, stirring device 81. DETAILED DESCRIPTION

[0022] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0023] like Figure 1 As shown, this embodiment discloses a soil treatment process, including the following treatment steps:

[0024] ① The soil in feed bin 1 is crushed by crushing device 11 and then placed in reaction tank 12. Crushing device 11 is used to crush the gravel in the soil. An EDTA aqueous solution is introduced into reaction tank 12. Heavy metal ions in the soil react with the EDTA to form EDTA-heavy metal complexes. The EDTA-heavy metal complexes are then mixed in the solution, allowing the EDTA to separate the heavy metal ions from the soil.

[0025] ② Reaction tank 12 is equipped with a drive unit 121 and a drive unit 2 122. Both drive units 121 and 122 are equipped with stirring rods, which extend into reaction tank 12. Drive units 121 and 122 are driven by an augers reduction motor and a thrust paddle reduction motor, respectively.

[0026] After the soil and the EDTA aqueous solution are stirred to make the reaction more complete, the soil and the EDTA aqueous solution are opened and discharged to the filter tank 14 through the valve body 13 at the bottom of the reaction tank 12.

[0027] ③ A filter plate is installed at the bottom of filter tank 14, through which the EDTA aqueous solution is filtered and discharged into liquid collection tank 15. Filter tank 14 is equipped with a discharge port to facilitate soil drainage. A spray pipe is also installed above filter tank 14 to further flush the soil through a spraying process, thereby reducing the residual EDTA heavy metal complex mixture on the soil surface and enhancing soil purification.

[0028] ④ The liquid accumulation pool 15 is provided with a liquid inlet 151, and the liquid inlet 151 is used to introduce sodium sulfide solution into the liquid accumulation pool 15. Sodium sulfide reacts with EDTA heavy metal complex to generate a precipitate of heavy metal sulfide, and EDTA is separated from heavy metal ions, and heavy metal ions exist in the precipitate.

[0029] ⑤ The reactants in the liquid pool 15 are passed into the container tank 2, and the container tank 2 separates the heavy metal sulfide precipitate from the liquid by filtration, wherein the liquid includes EDTA aqueous solution and excess sodium sulfide solution, and the precipitate is taken out.

[0030] ⑥ The liquid in step ⑤ is passed into the reaction tank 2 8, and hydrochloric acid and hydrogen peroxide are added to the reaction tank 2 8 to remove excess sodium sulfide;

[0031] ⑦ The DETA aqueous solution in reaction tank 2 8 is passed to reaction tank 1 12 through pipe 16, thereby recycling the DETA aqueous solution. A fluid pump 161 is installed in pipe 16 to drive the liquid flow.

[0032] like Figure 2 As shown, the container tank 2 includes a cavity 21 located at the upper part, and a valve body 22 is installed on the top of the container tank 2. After the valve body 22 is opened, the mixture of heavy metal sulfide precipitate and liquid in step ⑤ can be poured into the cavity 21.

[0033] like Figure 2As shown, the container tank 2 is mounted with a sleeve 3. The sleeve 3 includes a first channel 31 and a second channel 32 located below the first channel 31. The first channel 31 is located at the top of the sleeve 3 and is a tapered hole with a larger diameter at the top end than at the bottom end. The top end of the second channel 32 is connected to the bottom of the first channel 31. The second channel 32 is a cylindrical hole with a larger bottom diameter than the bottom diameter of the first channel 31.

[0034] A filter component 4 is installed in channel 1 31. The filter component 4 is made of sponge and is inserted into channel 1 31. The outer diameter of the filter component 4 matches the inner diameter of channel 1 31. The filter component 4 is located at the upper part of channel 1 31, and the outer peripheral wall of the filter component 4 fits the inner peripheral wall of channel 1 31.

[0035] By providing the tapered hole 1 31 and the tapered filter element 4 , when the filter element 4 is compressed in the axial direction, the inner wall of the hole 1 31 simultaneously generates radial internal pressure on the filter element 4 , thereby improving the liquid squeezing efficiency.

[0036] like Figure 2 As shown, a liquid outlet is provided at the bottom of the channel 1 31 and is connected to a valve body 3 6 . When the valve body 3 6 is opened, the liquid in the channel 1 31 can be discharged.

[0037] A piston plate 7 is slidably mounted in the second channel 32. The outer wall of the piston plate 7 is made of rubber and closely adheres to the inner wall of the second channel 32. When the piston plate 7 is in its upper limit position, it seals the upper end of the second channel 32, disconnecting the second channel 32 from the first channel 31. At this point, the liquid filtered by the filter element 4 flows above the piston plate 7 and can be discharged through the third valve body 6. The liquid discharged from the third valve body 6 is liquid that has not been spray-filtered, so its EDTA concentration is higher and can be used for recycling. The filtrate obtained after spraying, on the other hand, has a lower EDTA concentration and needs to be discharged separately.

[0038] Combine Figure 2 、 Figure 3 A retaining ring 54 is mounted on the top of the sleeve 3. This retaining ring 54 is a circular ring, with its bottom surface contacting the top surface of the filter element 4. A pressure plate 53 abuts the top surface of the filter element 4, which is inserted into the retaining ring 54. The inner diameter of the retaining ring 54 is the same as the outer diameter of the pressure plate 53. The pressure plate 53 is provided with multiple axial through-holes for liquid circulation. An insert 521 is mounted on the pressure plate 53, and a rod sleeve 52 is fixedly mounted on the bottom of the insert 521. The rod sleeve 52 passes through the filter element 4.

[0039] like Figure 3 As shown, the rod sleeve 52 is installed with a washer 522, which is inserted into the rod sleeve 52, and the bottom of the insert 521 presses the upper end of the washer 522. The washer 522 is made of rubber, and the cross section of the washer 522 is circular. The inner wall of the washer 522 extends out of the inner wall of the rod sleeve 52.

[0040] like Figure 2 As shown, the sleeve 3 is installed with a fixing plate 33, which is located below the piston plate 7. A driving component 51 is installed at the bottom of the fixing plate 33. The driving component 51 is an electric cylinder. Under the drive of the driving component 51, the rod body 5 can move up and down along the axial direction. The washer 522 is coaxially arranged with the rod body 5. Figure 3 As shown, the top of the rod body 5 can be inserted into the rod sleeve 52 , and a protrusion 56 is provided on the outer wall of the rod body 5 . The protrusion 56 can pass through the washer 522 , and the outer diameter of the protrusion 56 is greater than the inner diameter of the washer 522 .

[0041] like Figure 2 As shown, the sleeve 3 is installed with a fixing plate 55, which is located below the filter component 4 and is used to limit the filter component 4. The bottom of the rod sleeve 52 passes through the fixing plate 55. The bottom of the rod sleeve 52 is provided with a boss 523, and the outer diameter of the boss 523 is larger than the inner diameter of the fixing plate 55. Figure 2 、 Figure 3 When the position of the protrusion 56 is higher than the gasket 522, the protrusion 56 moves downward to squeeze the gasket 522 and push the gasket 522 to move downward. At the same time, the pressure plate 53 moves downward to squeeze the filter component 4, and the liquid in the filter component 4 is squeezed out. After the filter component 4 is compressed, the protrusion 56 is subjected to increased resistance from the gasket 522, and the protrusion 56 passes through the gasket 522 downward, and the filter component 4 rebounds; when the protrusion 56 is inserted upward into the gasket 522, the upper end of the boss 523 abuts against the fixing plate 55 to prevent the gasket 522 from moving upward.

[0042] By squeezing the filter component 4 , the liquid content in the filter component 4 can be quickly reduced, the liquid absorption capacity of the filter component 4 can be improved (when the liquid in the filter component 4 is saturated, the filtrate is slowly filtered), and the filtering efficiency can be improved.

[0043] like Figure 2 As shown, a push plate 213 is installed on one side of the container tank 2. The bottom position of the push plate 213 is at the same height as the top position of the pressure plate 53 and the fixing ring 54. A discharge port 211 is provided on the other side of the push plate 213. The discharge port 211 is opened and closed by a baffle 212 that can move left and right. The push plate 213 is located in the cavity 21. When the push plate 213 is in the right extreme position, it is tightly fitted against the inner wall of the container tank 2. When the push plate 213 moves to the left, the sediment can be pushed out of the discharge port 211.

[0044] Combine Figure 2 、 Figure 4, the piston plate 7 is provided with a through hole 1 71, and the minimum distance between the through hole 1 71 and the axis of the piston plate 7 is greater than the inner diameter of the channel 1 31. When the liquid initially filtered from the soil in the filter pool 14 enters the container tank 2 through the liquid pool 15, it is discharged from the valve body 3 6. When the soil in the filter pool 14 enters the container tank 2 through the liquid pool 15 through the spray, the piston plate 7 moves downward, and the through hole 1 71 connects the channel 1 31 and the channel 2 32, and the liquid flows out from the liquid outlet at the bottom of the channel 2 32. Specifically, combined with Figure 2 、 Figure 4 There are multiple through holes 71 evenly distributed along the circumference of the piston plate 7. The through hole 71 axially penetrates the piston plate 7. A connecting plate 72 is installed at the bottom of the piston plate 7. The rod body 5 passes through the connecting plate 72. A groove 721 is provided at the upper end of the connecting plate 72. Figure 5 As shown, the groove body 721 is annular and is connected to the through hole 1 71. Figure 4 As shown, the bottom of the tank body 721 is connected to a second through hole 722 , and the second through hole 722 is connected to the liquid outlet through a hose 73 to discharge the liquid entering the first through hole 71 out of the container tank 2 .

[0045] like Figure 2 As shown, the bottom of the connecting plate 72 is abutted against a spring 34 so that the piston plate 7 can seal the upper end of the second channel 32.

[0046] like Figure 2 As shown, the rod body 5 is equipped with a baffle 57, which is located above the piston plate 7. When the baffle 57 moves downward, it abuts against the piston plate 7 and pushes the piston plate 7 downward. The rod body 5 passes through the piston plate 7, and the rod body 5 and the piston plate 7 are slidingly sealed.

[0047] When the baffle 57 pushes the piston plate 7 to move downward, the protrusion 56 has already separated from the gasket 522 downward, the filter component 4 is in the initial rebound state, and the pores in the filter component 4 are in the maximum state. When the residual amount of liquid is small, the filter component 4 is squeezed, and the liquid in the filter component 4 will be squeezed out in all directions, resulting in a poor effect. At this time, the air pressure below the filter component 4 is lower than the air pressure of the cavity 21 due to the downward movement of the piston plate 7. The liquid in the filter component 4 easily flows downward under the action of airflow and gravity and gathers at the bottom of the filter component 4. When the filter component 4 is compressed again, it is convenient to squeeze it downward, reducing the residual amount of liquid in the filter component 4, thereby improving the recovery rate of the EDTA recovery solution.

[0048] The above description is merely a preferred embodiment of the present invention. The scope of protection of the present invention is not limited to the above embodiment. All technical solutions based on the concept of the present invention are within the scope of protection of the present invention. It should be noted that for those skilled in the art, various improvements and modifications that do not depart from the principles of the present invention should also be considered within the scope of protection of the present invention.

Claims

1. A soil treatment process, characterized in that: The following processing steps are included: ① placing soil into a reaction tank (12), into which an EDTA aqueous solution is introduced, so that heavy metal ions in the soil react with EDTA to form EDTA heavy metal complexes; ② After the soil and EDTA aqueous solution are stirred, the soil and EDTA aqueous solution are discharged together into the filtration tank (14); ③ The EDTA aqueous solution is discharged from the filtration tank (14) to the liquid accumulation tank (15); ④ Sodium sulfide solution is introduced into the liquid pool (15), sodium sulfide reacts with EDTA heavy metal complex to generate heavy metal sulfide precipitate, and EDTA is separated from heavy metal ions; ⑤ The reactants in the liquid accumulation pool (15) are introduced into the container tank (2), and the container tank (2) separates the heavy metal sulfide precipitate from the liquid by filtering; ⑥ The liquid in step ⑤ is passed into the second reaction tank (8), and hydrochloric acid and hydrogen peroxide are added to the second reaction tank (8) to react and remove excess sodium sulfide; ⑦ The DETA aqueous solution in the second reaction tank (8) is passed to the first reaction tank (12) through the pipeline (16); The container tank (2) is installed with a sleeve (3), the sleeve (3) includes a first channel (31) and a second channel (32) located below the first channel (31), the first channel (31) is installed with a filter component (4), the filter component (4) is inserted into the first channel (31), and the bottom of the first channel (31) is provided with a liquid outlet and is connected to a valve body (6); A pressing plate (53) is installed on the top of the filter component (4), the lower end of the pressing plate (53) is in contact with the upper end surface of the filter component (4), the pressing plate (53) is installed with a rod sleeve (52), the rod sleeve (52) passes through the filter component (4), and the rod sleeve (52) is installed with a gasket (522), and the gasket (522) is inserted into the rod sleeve (52); The sleeve (3) is provided with a rod body (5), the rod body (5) is capable of moving up and down in the axial direction, the outer wall of the rod body (5) is provided with a protrusion (56), the protrusion (56) is capable of passing through the washer (522), and the outer diameter of the protrusion (56) is larger than the inner diameter of the washer (522); The second hole (32) is slidably connected to a piston plate (7), and when the piston plate (7) is at the upper limit position, the upper end of the second hole (32) is closed to disconnect the second hole (32) from the first hole (31). The piston plate (7) is provided with a through hole (71), and the minimum distance between the through hole (71) and the axis of the piston plate (7) is greater than the inner diameter of the first hole (31); The rod body (5) is provided with a baffle (57), and the baffle (57) is located above the piston plate (7); The washer (522) is coaxially arranged with the rod body (5); The bottom of the piston plate (7) is connected to a connecting plate (72), and the connecting plate (72) is provided with a groove body (721) and a second through hole (722). The groove body (721) is communicated with the second through hole (722), and the second through hole (722) is connected to a hose (73). The first through hole (71) is communicated with the groove body (721).

2. A soil treatment process according to claim 1, characterized in that: The soil in step ① is crushed by the crushing device (11) to crush the stones in the soil, and then enters the reaction tank 1 (12).

3. A soil treatment process according to claim 1, characterized in that: The reaction pool 1 (12) is equipped with a driving device 1 (121) and a driving device 2 (122), and the driving device 1 (121) and the driving device 2 (122) are both equipped with a stirring rod, and the stirring rod extends into the reaction pool 1 (12).

4. A soil treatment process according to claim 1, characterized in that: The through hole 1 (71) is provided with a plurality of holes along the circumference of the piston plate (7), and the groove body (721) is in the shape of a circular ring.

5. A soil treatment process according to claim 1, characterized in that: The hole one (31) is a tapered hole.

6. A soil treatment process according to claim 1, characterized in that: A discharge port (211) is provided on one side of the container tank (2), and a push plate (213) is installed on the other side of the container tank (2). The push plate (213) can be moved closer to or farther away from the discharge port (211), and the bottom position of the push plate (213) is at the same height as the top position of the pressure plate (53).

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