Soil treatment process

Abstract

The invention discloses a soil treatment process which comprises the following treatment steps: (1) putting soil into a reaction tank I, introducing an EDTA (Ethylene Diamine Tetraacetic Acid) aqueous solution into the reaction tank I, and carrying out complexation reaction on heavy metal ions in the soil and EDTA to generate an EDTA heavy metal complex; (2) after the soil and the EDTA aqueous solution are stirred, the soil and the EDTA aqueous solution are discharged into a filter tank together; (3) discharging the EDTA aqueous solution from the filter tank to a liquid accumulation tank; (4) introducing a sodium sulfide solution into the liquid accumulation tank, reacting sodium sulfide with the EDTA heavy metal complex to generate a precipitate of heavy metal sulfide, and separating EDTA from heavy metal ions; (5) introducing reactants in the liquid accumulation pool into a container tank, and separating the precipitate of the heavy metal sulfide from the liquid by the container tank through filtration; (6) introducing the liquid in the step (5) into a reaction tank II, adding hydrochloric acid and hydrogen peroxide into the reaction tank II, and reacting to remove excessive sodium sulfide; and (7) introducing the DETA aqueous solution in the reaction tank II into the reaction tank I through a pipeline. According to the soil treatment process provided by the invention, the EDTA solution is recycled, and the process cost is reduced.

Description

Technical Field

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

[0002] The heavy metal pollution of soil is becoming increasingly serious. One kind of soil treatment process uses an EDTA solution to carry out a complexation reaction with heavy metal ions in the soil to separate the heavy metal ions in the soil from the soil, so as to improve the soil and complete the recycling of the soil. However, the complex formed after the EDTA solution reacts with the heavy metal ions in the soil is likely to cause secondary pollution, and the cost of EDTA is relatively high. Direct disposal as waste increases the overall process cost and needs to be improved. Summary of the Invention

[0003] The purpose of the present invention is to overcome the deficiencies of the above-mentioned prior art, and to provide a soil treatment process that recycles and uses the EDTA solution to reduce the process cost.

[0004] To achieve the above purpose, the present invention adopts the following technical solutions: A soil treatment process includes the following treatment steps: ①Put the soil into reaction tank 1, and introduce an EDTA aqueous solution into reaction tank 1. The heavy metal ions in the soil react with EDTA to form an EDTA heavy metal complex; ②After the soil and the EDTA aqueous solution are stirred, the soil and the EDTA aqueous solution are discharged to the filtration tank together; ③The EDTA aqueous solution is discharged from the filtration tank to the liquid accumulation tank; ④A sodium sulfide solution is introduced into the liquid accumulation tank, and sodium sulfide reacts with the EDTA heavy metal complex to form a precipitate of heavy metal sulfide, and the EDTA is separated from the heavy metal ions; ⑤The reactants in the liquid accumulation tank are introduced into a container tank, and the container tank separates the precipitate of heavy metal sulfide from the liquid through filtration; ⑥The liquid in step ⑤ is introduced into reaction tank 2, and hydrochloric acid and hydrogen peroxide are added to reaction tank 2 to react and remove the excessive sodium sulfide; ⑦The DETA aqueous solution in reaction tank 2 is led to reaction tank 1 through a pipeline.

[0005] The present invention is further arranged such that the soil in step ① is broken by a crushing device to break the stones in the soil, and then enters reaction tank 1.

[0006] The present invention is further arranged such that reaction tank 1 is equipped with driving device 1 and driving device 2. Both driving device 1 and driving device 2 are equipped with stirring rods, and the stirring rods extend into reaction tank 1.

[0007] The present invention is further configured such that a sleeve is installed on the container tank. The sleeve includes a first passage and a second passage located below the first passage. A filtering component is installed in the first passage, and the filtering component is inserted into the first passage. An outlet is provided at the bottom of the first passage and is connected to a third valve body. A pressing plate is installed on the top of the filtering component, and the lower end of the pressing plate is in contact with the upper end face of the filtering component. A rod sleeve is installed on the pressing plate, and the rod sleeve passes through the filtering component. A washer is installed on the rod sleeve, and the washer is inserted into the rod sleeve. A rod body is installed on the sleeve, and the rod body can move up and down along the axial direction. A protruding portion is provided on the outer wall of the rod body, and the protruding portion can pass through the washer. The outer diameter of the protruding portion is larger than the inner diameter of the washer. A piston plate is slidably connected and installed in the second passage. When the piston plate is at the upper limit position, it closes the upper end of the second passage to disconnect the second passage from the first passage. The piston plate is provided with a first through hole, and the minimum distance between the first through hole and the axis of the piston plate is larger than the inner diameter of the first passage. A baffle is installed on the rod body, and the baffle is located above the piston plate.

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

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

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

[0011] The present invention is further configured such that the first passage 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 approach or move away from the discharge port, and the bottom position of the push plate is at the same height as the top position of the pressing plate.

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

[0014] 1. By reacting sodium sulfide with EDTA heavy metal complexes to generate heavy metal sulfide precipitates, the heavy metals are separated from EDTA. After EDTA is released, it is recycled, reducing the usage cost of the 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 residue of EDTA in the soil. The soil is better regenerated. The liquid obtained from the primary filtration and the liquid obtained from the re - filtration through spraying are treated separately to ensure the concentration of the reused EDTA solution, eliminating the concentration purification process steps and reducing the process cost. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 It is a schematic diagram of the process equipment for the embodiment;

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

[0018] Figure 3 It is Figure 2 an enlarged view of part A in

[0019] Figure 4 It is Figure 2 an enlarged view of part B in

[0020] Figure 5 It is a cross-sectional view of the connecting plate in the embodiment.

[0021] Reference numerals: feed bin 1, crushing device 11, first reaction tank 12, first driving device 121, second driving device 122, first valve body 13, filtration 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, second valve body 22, sleeve 3, first hole 31, second hole 32, first fixing plate 33, spring 34, filtering component 4, rod body 5, driving component 51, rod sleeve 52, inserting cylinder 521, washer 522, convex platform 523, pressing plate 53, fixing ring 54, second fixing plate 55, protruding part 56, baffle 57, third valve body 6, piston plate 7, first through hole 71, connecting plate 72, groove 721, second through hole 722, hose 73, second reaction tank 8, stirring device 81. Detailed implementation manners

[0022] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

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

[0024] ① After the soil in the feed bin 1 is crushed by the crushing device 11, it is put into the first reaction tank 12. The crushing device 11 is used to crush the stones in the soil. An EDTA aqueous solution is introduced into the first reaction tank 12. Heavy metal ions in the soil react with EDTA to form EDTA heavy metal complexes. The EDTA heavy metal complexes are mixed in the solution, thereby realizing the separation of heavy metal ions in the soil from the soil by EDTA.

[0025] ②The first reaction tank 12 is equipped with a first driving device 121 and a second driving device 122. Both the first driving device 121 and the second driving device 122 are equipped with stirring rods that extend into the first reaction tank 12. The first driving device 121 and the second driving device 122 are respectively driven by a screw conveyor reduction motor and a thrust paddle reduction motor.

[0026] The soil and the EDTA aqueous solution are stirred to make the reaction more complete, and then the soil and the EDTA aqueous solution are discharged together through the valve body 13 at the bottom of the first reaction tank 12 into the filtration tank 14.

[0027] ③The bottom of the filtration tank 14 is equipped with a filter plate, and the EDTA aqueous solution is filtered and discharged from the filtration tank 14 into the liquid accumulation tank 15. The filtration tank 14 is equipped with a discharge port to discharge the soil. A spray pipe is also provided above the filtration tank 14. By sprinkling water, the soil is further washed to reduce the residue of the EDTA heavy metal complex mixture on the soil surface and enhance the purification effect of the soil.

[0028] ④The liquid accumulation tank 15 is provided with a liquid inlet 151. A sodium sulfide solution is introduced into the liquid accumulation tank 15 through the liquid inlet 151. Sodium sulfide reacts with the EDTA heavy metal complex to form a precipitate of heavy metal sulfide, and the EDTA is separated from the heavy metal ions. The heavy metal ions are present in the precipitate.

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

[0030] ⑥The liquid in step ⑤ is introduced into the second reaction tank 8. Hydrochloric acid and hydrogen peroxide are added to the second reaction tank 8 to react and remove the excess sodium sulfide;

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

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

[0033] As Figure 2As shown, 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 located at the top of the sleeve 3. The first channel 31 is a tapered hole, and the diameter of the upper end of the first channel 31 is larger than that of the lower end. The upper end of the second channel 32 communicates with the bottom of the first channel 31. The second channel 32 is a cylindrical channel, and the diameter of the bottom of the second channel 32 is larger than that of the bottom of the first channel 31.

[0034] The first channel 31 is installed with a filtering component 4. The filtering component 4 is made of sponge material. The filtering component 4 is inserted into the first channel 31. The outer diameter of the filtering component 4 matches the inner diameter of the first channel 31. The filtering component 4 is located in the upper part of the first channel 31, and the outer peripheral wall of the filtering component 4 fits against the inner peripheral wall of the first channel 31.

[0035] By setting the tapered first channel 31 and the tapered filtering component 4, when the filtering component 4 is axially compressed, the inner wall of the first channel 31 simultaneously generates a radial internal pressure on the filtering component 4, improving the liquid squeezing efficiency.

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

[0037] The second channel 32 is slidably connected with a piston plate 7. The outer wall of the piston plate 7 is made of rubber material, and the outer peripheral wall of the piston plate 7 closely adheres to the inner peripheral wall of the second channel 32. When the piston plate 7 is in the upper limit position, it closes the upper end of the second channel 32, so that the second channel 32 is disconnected from the first channel 31. At this time, the liquid filtered by the filtering component 4 flows to the upper part of the piston plate 7 and can be discharged from the third valve body 6. The liquid discharged from the third valve body 6 is the liquid that has not been spray-filtered, so its EDTA concentration is relatively high and can be recycled. The EDTA concentration in the filtered liquid obtained after spraying is relatively low and needs to be discharged and treated separately.

[0038] Combined with Figure 2 、 Figure 3 , a fixing ring 54 is installed at the top of the sleeve 3. The fixing ring 54 is a circular ring structure, and the bottom surface of the fixing ring 54 fits against the top surface of the filtering component 4. A pressing plate 53 abuts against the upper end surface of the filtering component 4. The pressing plate 53 can be inserted into the fixing ring 54. The inner diameter of the fixing ring 54 is the same as the outer diameter of the pressing plate 53. The pressing plate 53 is axially provided with a plurality of through holes for liquid circulation. The pressing plate 53 is installed with an insertion cylinder 521, and a rod sleeve 52 is fixedly installed at the bottom of the insertion cylinder 521. The rod sleeve 52 passes through the filtering component 4.

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

[0040] AsFigure 2 As shown, a fixing plate one 33 is installed on the sleeve 3. The fixing plate one 33 is located below the piston plate 7. A driving component 51 is installed at the bottom of the fixing plate one 33. The driving component 51 is an electric cylinder. Driven by the driving component 51, the rod body 5 can move up and down along the axis. The washer 522 is coaxially arranged with the rod body 5. As Figure 3 shown, the top of the rod body 5 can be inserted into the rod sleeve 52. A convex part 56 is provided on the outer wall of the rod body 5. The convex part 56 can pass through the washer 522. The outer diameter of the convex part 56 is larger than the inner diameter of the washer 522.

[0041] As Figure 2 shown, a fixing plate two 55 is installed on the sleeve 3. The fixing plate two 55 is located below the filtering component 4. The fixing plate two 55 is used to limit the filtering component 4. The bottom of the rod sleeve 52 passes through the fixing plate two 55. A boss 523 is provided at the bottom of the rod sleeve 52. The outer diameter of the boss 523 is larger than the inner diameter of the fixing plate two 55. Combining Figure 2 、 Figure 3 , when the position of the convex part 56 is higher than the washer 522, the convex part 56 moves downward to squeeze the washer 522 and push the washer 522 to move downward. At the same time, the pressing plate 53 moves downward to squeeze the filtering component 4, and the liquid in the filtering component 4 is pressed out. After the filtering component 4 is compressed, the resistance of the convex part 56 to the washer 522 increases, and the convex part 56 passes through the washer 522 downward, and the filtering component 4 rebounds; when the convex part 56 is inserted into the washer 522 upward, the upper end of the boss 523 abuts against the fixing plate two 55 to prevent the washer 522 from moving upward.

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

[0043] As Figure 2 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 positions of the pressing plate 53 and the fixing ring 54. An outlet 211 is provided on the other side of the push plate 213. The opening and closing of the outlet 211 is realized by a baffle 212 that can move left and right. When the push plate 213 is located at the rightmost limit position in the cavity 21, it is hermetically attached to the inner wall of the container tank 2. When the push plate 213 moves to the left, it can push the precipitate out of the outlet 211.

[0044] Combining Figure 2 、 Figure 4, the piston plate 7 is provided with a first through hole 71, and the minimum distance between the first through hole 71 and the axis of the piston plate 7 is greater than the inner diameter of the first channel 31. When the liquid initially filtered by the soil in the filtration tank 14 enters the container tank 2 through the liquid accumulation tank 15 and then discharges from the valve body three 6. When the soil in the filtration tank 14 enters the container tank 2 through spraying via the liquid accumulation tank 15, the piston plate 7 moves downward, and the first through hole 71 connects the first channel 31 and the second channel 32, and the liquid passes out from the liquid outlet at the bottom of the second channel 32. Specifically, in combination with Figure 2 , Figure 4 , a plurality of first through holes 71 are evenly distributed along the circumferential direction of the piston plate 7, the first through holes 71 axially penetrate the piston plate 7, a connecting disk 72 is installed at the bottom of the piston plate 7, the rod body 5 passes through the connecting disk 72, and a groove body 721 is provided at the upper end of the connecting disk 72. As Figure 5 shown, the groove body 721 is circular, the groove body 721 is communicated with the first through hole 71. As Figure 4 shown, a second through hole 722 is communicated at the bottom of the groove body 721, 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 from the container tank 2.

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

[0046] As Figure 2 shown, a baffle 57 is installed on the rod body 5, the baffle 57 is located above the piston plate 7, and 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 is slidably sealed with the piston plate 7.

[0047] When the baffle 57 pushes the piston plate 7 downward, the convex portion 56 has already moved downward away from the washer 522, and 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 liquid residue is less, squeezing the filter component 4 will cause the liquid in the filter component 4 to be extruded in all directions, resulting in a poor effect. At this time, by moving the piston plate 7 downward, the air pressure below the filter component 4 is lower than the air pressure in the cavity 21, and the liquid in the filter component 4 is easily flowing downward under the action of air flow and gravity and gathering at the bottom of the filter component 4. When the filter component 4 is compressed again, it is convenient to extrude it downward to reduce the liquid residue in the filter component 4 and improve the recovery rate of the EDTA recovery solution.

[0048] The above is only the preferred embodiment of the present invention, and the protection scope of the present invention is not limited to the above embodiments. All technical solutions falling within the idea of the present invention belong to the protection scope of the present invention. It should be noted that for those of ordinary skill in the art in this technical field, without departing from the principle of the present invention, several improvements and retouches should also be regarded as the protection scope of the present invention.

Claims

1. A soil treatment process, characterized in that, It includes the following treatment steps: ①Put the soil into the first reaction tank (12), and introduce an EDTA aqueous solution into the first reaction tank (12). The heavy metal ions in the soil react with EDTA to form EDTA heavy metal complexes; ②After the soil and the EDTA aqueous solution are stirred, the soil and the EDTA aqueous solution are discharged into the filtration tank (14) together; ③The EDTA aqueous solution is discharged from the filtration tank (14) to the liquid accumulation tank (15); ④Introduce a sodium sulfide solution into the liquid accumulation tank (15). Sodium sulfide reacts with the EDTA heavy metal complex to form a precipitate of heavy metal sulfide, and EDTA is separated from the heavy metal ions; ⑤The reactants in the liquid accumulation tank (15) are introduced into the container tank (2), and the container tank (2) separates the precipitate of heavy metal sulfide from the liquid by filtration; ⑥Introduce the liquid in step ⑤ into the second reaction tank (8), and add hydrochloric acid and hydrogen peroxide to the second reaction tank (8) to react and remove the excessive sodium sulfide; ⑦The DETA aqueous solution in the second reaction tank (8) is led to the first reaction tank (12) through the pipeline (16).

2. The 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 first reaction tank (12).

3. A soil treatment process according to claim 1, characterized in that, The first reaction tank (12) is equipped with a first driving device (121) and a second driving device (122). The first driving device (121) and the second driving device (122) are both equipped with stirring rods, and the stirring rods extend into the first reaction tank (12).

4. A soil treatment process according to claim 1, characterized in that, The container tank (2) is equipped with a sleeve (3). The sleeve (3) includes a first pore (31) and a second pore (32) located below the first pore (31). The first pore (31) is equipped with a filtering component (4). The filtering component (4) is inserted into the first pore (31). The bottom of the first pore (31) is provided with a liquid outlet and is connected to a third valve body (6); The top of the filtering component (4) is equipped with a pressing plate (53). The lower end of the pressing plate (53) fits with the upper end surface of the filtering component (4). The pressing plate (53) is equipped with a rod sleeve (52). The rod sleeve (52) passes through the filtering component (4). The rod sleeve (52) is equipped with a washer (522). The washer (522) is inserted into the rod sleeve (52); The sleeve (3) is equipped with a rod body (5). The rod body (5) can move up and down along the axis. The outer wall of the rod body (5) is provided with a protruding part (56). The protruding part (56) can pass through the washer (522). The outer diameter of the protruding part (56) is larger than the inner diameter of the washer (522); The second pore (32) is slidably connected with a piston plate (7). When the piston plate (7) is at the upper limit position, it closes the upper end of the second pore (32) to disconnect the second pore (32) from the first pore (31). The piston plate (7) is provided with a first through hole (71). The minimum distance between the first through hole (71) and the axis of the piston plate (7) is larger than the inner diameter of the first pore (31); The rod body (5) is equipped with a baffle (57). The baffle (57) is located above the piston plate (7).

5. A soil treatment process according to claim 4, characterized in that, The washer (522) is coaxially arranged with the rod body (5).

6. A soil treatment process according to claim 4, characterized in that, A connecting disc (72) is connected to the bottom of the piston plate (7). The connecting disc (72) is provided with a groove body (721) and a second through hole (722). The groove body (721) communicates with the second through hole (722). A hose (73) is connected to the second through hole (722), and the first through hole (71) communicates with the groove body (721).

7. A soil treatment process according to claim 6, characterized in that, A plurality of the first through holes (71) are provided along the circumferential direction of the piston plate (7), and the groove body (721) is annular.

8. A soil treatment process according to claim 4, characterized in that, The first hole passage (31) is a tapered hole.

9. A soil treatment process according to claim 4, 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 approach or move 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 pressing plate (53).

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