Magnetic filtering device for cold rolling wastewater and use method of magnetic filtering device

Abstract

The invention discloses a cold rolling wastewater magnetic filtering device which comprises a shell, a left side end cover and a right side end cover are arranged at the two ends of the shell respectively, the right end of a left air inlet sleeve penetrates through the left side end cover in a sealed mode, a mud scraping air inlet is formed in the left air inlet sleeve, and the left end of a right air inlet sleeve penetrates through the right side end cover in a sealed mode. A piston reset air inlet is formed in the right air inlet guide pipe; a left connecting piece, a magnetic bar and a right connecting piece which have the same outer diameter and are sequentially connected are arranged in the shell, a water inlet, a water outlet, a sludge discharge port and an exhaust port are formed in the shell, the sludge discharge port is located below the right connecting piece, and the exhaust port is located on the left side of the left connecting piece; the inner wall of the mud scraping piston is in sliding fit with the peripheral surface of the outer wall of the magnetic bar, the outer wall of the mud scraping piston is in sliding fit with the inner wall of the shell, and the outer wall of the mud scraping piston and the inner wall of the shell are kept in contact to scrape attachments. The mud scraping function is achieved by arranging the mud scraping piston, the structure is simple, and use is convenient.

Description

Technical Field

[0001] This invention belongs to the field of environmental wastewater treatment, specifically relating to a magnetic filtration device for cold rolling wastewater, and also to a method of using the magnetic filtration device for cold rolling wastewater, applicable to magnetic filtration of cold rolling wastewater. Background Technology

[0002] Wastewater resource utilization and "zero discharge" are gradually becoming the development goals of steel enterprises. Cold rolling wastewater is generally sent to wastewater treatment plants for treatment. Under the current trend of zero discharge and energy conservation and emission reduction, the reuse and treatment of cold rolling wastewater is a promising treatment method.

[0003] Cold rolling wastewater, including acidic and alkaline wastewater, emulsion wastewater, and finishing machine wastewater, contains a certain amount of zinc powder, iron powder, and oil. It needs to be pretreated before entering the subsequent membrane treatment device to reduce the pollution of the subsequent membrane treatment device. Magnetic filtration device can effectively remove iron powder from cold rolling wastewater. Therefore, magnetic filtration technology is widely used in the treatment of cold rolling wastewater.

[0004] Currently, rotary drum magnetic filters are commonly used in cold rolling wastewater treatment. These devices have a large footprint, and because they rely on gravity flow, combining them with other processes requires additional booster pumps and water tanks. Furthermore, the magnets in rotary drum magnetic filters are partially submerged in the wastewater, further increasing the footprint. While existing magnetic rod filters have fully submerged magnets, they lack automatic sludge scraping mechanisms, making maintenance and repair inconvenient and unsuitable for factory operation and management. Limited space within factory workshops restricts equipment footprint, and new wastewater treatment equipment must consider automated operation control to reduce maintenance frequency. Therefore, magnetic filtration devices with a small footprint, stable treatment effect, and high degree of automation are essential. Summary of the Invention

[0005] The purpose of this invention is to provide a magnetic filtration device for cold rolling wastewater and its usage method, so as to solve the problems mentioned in the background art, achieve stable treatment effect, reduce equipment footprint, realize automated operation, and reduce manual maintenance.

[0006] To achieve the above objectives, the present invention provides the following technical solution: A magnetic filtration device for cold rolling wastewater includes a housing with a left end cap and a right end cap at both ends. A left air inlet sleeve passes through the left end cap in a sealed manner and has a sludge scraping air inlet. A right air inlet sleeve passes through the right end cap in a sealed manner and has a piston reset air inlet. Inside the housing are a left connector, a magnetic rod, and a right connector of the same outer diameter connected in sequence. The housing has a water inlet, a water outlet, a sludge discharge outlet, and an exhaust outlet. The water inlet and water outlet are located at opposite ends of the magnetic rod, with the water outlet above the water inlet. The sludge discharge outlet is located below the right connector, and the exhaust outlet is located to the left of the left connector. A sludge scraping piston is fitted onto the magnetic rod. The inner wall of the sludge scraping piston slides against the outer wall of the magnetic rod, and the outer wall of the sludge scraping piston slides against the inner wall of the housing, maintaining contact to scrape off adhering substances.

[0007] It also includes a left magnetic rod connecting rod and a right magnetic rod connecting rod. The right end of the left magnetic rod connecting rod passes through the left intake sleeve and is threaded to the left end of the left connector. The left end of the left magnetic rod connecting rod is screwed into a nut, and the nut is pressed against the left side of the left fixing plate. The left end of the left intake sleeve passes through the left fixing plate and is fixedly connected to the left fixing plate. The left end of the right magnetic rod connecting rod passes through the right intake sleeve and is threaded to the right end of the right connector. The right end of the right magnetic rod connecting rod is screwed into a nut, and the nut is pressed against the right side of the right fixing plate. The right end of the right intake sleeve passes through the right fixing plate and is fixedly connected to the right fixing plate.

[0008] Both the left and right magnetic rod connecting rods are fitted with sealing rings. The sealing ring fitted on the left magnetic rod connecting rod is located on the left side of the mud scraping air inlet, and the sealing ring fitted on the right magnetic rod connecting rod is located on the right side of the piston reset air inlet.

[0009] The sludge scraper piston includes a left sludge scraper sleeve, a sludge scraper connecting sleeve, and a right sludge scraper sleeve connected in sequence. The outer walls of the left and right sludge scraper sleeves are provided with outer annular grooves, and an outer sealing ring is fitted in the outer annular grooves. The outer ring wall of the outer sealing ring slides in contact with the inner wall of the outer shell and also serves as a dynamic seal. The inner walls of the left and right sludge scraper sleeves are provided with inner annular grooves, and an inner sealing ring is fitted in the inner annular grooves. The inner ring wall of the inner sealing ring slides in contact with the outer wall of the magnetic rod and also serves as a dynamic seal.

[0010] The right connector includes a right connector fixing joint, a right connector connecting rod, and a right connector magnetic rod connecting head connected in sequence. The right connector magnetic rod connecting head is fixedly connected to the magnetic rod. There are multiple right connector connecting rods that are evenly distributed at circumferential intervals. The right connector fixing joint is threaded to the left end of the right magnetic rod connecting rod.

[0011] The left connector has a hollow interior forming an air chamber. The side wall of the left connector has circumferentially distributed air chamber inlets, and the left end face of the left connector has an air chamber outlet. The right end of the left connector is connected to a magnetic rod.

[0012] Both the left and right end caps are equipped with buffer devices on their inner walls. Each buffer device includes a pressure sensor, a spring, a guide sleeve, and a buffer ring connected in sequence. The buffer devices on the inner walls of the left and right end caps are a left buffer device and a right buffer device, respectively. The pressure sensor of the left buffer device is located inside the left end cap, and the buffer ring and guide sleeve of the left buffer device are fitted onto the left end of the left connector. The pressure sensor of the right buffer device is located inside the right end cap, and the buffer ring and guide sleeve of the right buffer device are fitted onto the right end of the right connector.

[0013] The buffer ring is provided with uniform air passages, and the area of ​​the air passages is 10 to 15% of the area of ​​the buffer ring.

[0014] Pressure gauges are installed on the connecting pipes of the inlet and outlet.

[0015] A method of using a magnetic filtration device for cold rolling wastewater as described above includes the following steps: Step 1: Disconnect the corresponding connecting pipes of the inlet, outlet, sludge discharge port, and sludge scraper air inlet. Connect the corresponding connecting pipes of the piston reset air inlet and outlet. Introduce compressed air through the piston reset air inlet to reset the sludge scraper piston under the action of the compressed air. After the sludge scraper piston resets, disconnect the corresponding connecting pipes of the piston reset air inlet and outlet. The reset process is as follows: Compressed air enters the housing through the piston reset inlet and the gap between the right inlet sleeve and the right magnetic rod connecting rod. It then passes through the air passage and the gap between the buffer ring and the housing, acting on the right scraper sleeve. Driven by the compressed air, the scraper piston moves to the left. When the scraper piston contacts the left buffer device, the spring in the left buffer device is in its unloaded state, and the right scraper sleeve covers the air chamber inlet. As the spring in the left buffer device contracts, the right scraper sleeve moves past the air chamber inlet to the left of the air chamber inlet. Compressed air enters the air chamber from the air chamber inlet, then leaves the air chamber from the air chamber outlet, and finally flows out from the exhaust port. As air flows out of the exhaust port, the thrust of the compressed air on the scraper piston decreases rapidly. When the force exerted by the spring in the left buffer device on the scraper piston is balanced with the thrust of the compressed air on the scraper piston, the value of the pressure sensor in the left buffer device is stable. Then, the connecting pipe of the piston reset air inlet is slowly cut off. During the process of slowly cutting off the connecting pipe of the piston reset air inlet, the scraper piston moves slowly to the right. When the connecting pipe of the piston reset air inlet is completely cut off, the spring in the left buffer device returns to its natural state, and the right scraper sleeve covers the air chamber air inlet and is located to the left of the water inlet, completing the reset of the scraper piston. Step 2: Connect the corresponding pipes of the inlet and outlet. The cold rolling wastewater enters the shell through the inlet, flows through the flow channel, and then flows out through the outlet, completing the filtration of the cold rolling wastewater. The specific process is as follows: When cold rolling wastewater enters the outer shell through the inlet, the scraper piston is in the reset state. The right scraper sleeve covers the air inlet of the air chamber and is located on the left side of the inlet. The right scraper sleeve will not affect the water intake. Since the water pressure is much lower than the compressed air pressure, the reset scraper piston is always covered on the air inlet of the air chamber under the action of the spring in the left buffer device. The water cannot enter the air chamber and flows along the flow channel, eventually flowing out from the outlet. Step 3: When the pressure difference between the inlet and outlet reaches the set threshold, disconnect the corresponding connecting pipes of the inlet and outlet 5, and open the corresponding connecting pipes of the sludge scraper air inlet and sludge discharge outlet. Compressed air enters the sludge scraper piston from the sludge scraper air inlet, and the sludge scraping action is completed under the action of the compressed air. When the pressure value of the pressure sensor in the right buffer device stabilizes, close the corresponding connecting pipes of the sludge scraper air inlet and sludge discharge outlet. The sludge scraping process is as follows: Compressed air is introduced into the scraper air inlet. The compressed air sequentially passes through the gap between the air chamber inlet and the left magnetic rod connecting rod, the air chamber outlet, the air chamber, and the air chamber inlet into the gap between the magnetic rod and the outer shell. This compressed air acts on the left side of the scraper piston, pushing it to slide to the right. When the right scraper sleeve passes the right connecting part magnetic rod connector, the scraped iron powder is discharged from the gap in the right connecting rod and the mud discharge port. The scraper piston continues to move to the right, decelerating under the action of the right buffer device. After the left scraper sleeve passes the right connecting part magnetic rod connector, the compressed air... Compressed air flows out of the mud discharge port through the gap between the connecting rods of the right connector. The thrust of the compressed air on the mud scraper piston decreases as the compressed air is discharged. The force of the spring in the right buffer device on the mud scraper piston gradually reaches equilibrium with the thrust of the compressed air on the mud scraper piston. At this time, the pressure value of the pressure sensor in the right buffer device is in a stable state. The corresponding connecting pipes of the mud scraper air inlet and mud discharge port are closed. Finally, the spring in the right buffer device is in a natural state, and the left mud scraper sleeve is located at the magnetic rod connector of the right connector. Step 4: Repeat steps 1 to 3 to complete the next cold rolling wastewater treatment.

[0016] Compared with the prior art, the beneficial effects of the present invention are: 1. The present invention provides a mud scraping piston sleeved on a magnetic rod. The inner wall of the mud scraping piston slides in contact with the outer wall of the magnetic rod, and the outer wall of the mud scraping piston slides in contact with the inner wall of the outer shell. The mud scraping piston also serves as a dynamic sealing element. The mud scraping function is accomplished by setting the mud scraping piston. 2. The mud discharge port is located below the right connector. The right connector includes a right connector fixing joint, a right connector connecting rod and a right connector magnetic rod connecting head connected in sequence. There are multiple right connector connecting rods that are evenly distributed in a circumferential interval. When the iron powder inside the shell is pushed to the right connector position by the mud scraper piston, the iron powder can be smoothly discharged from the mud discharge port. 3. The left connector has a hollow interior forming an air chamber. The side wall of the left connector is provided with circumferentially distributed air chamber inlets, and the left end of the left connector is provided with an air chamber outlet. When the mud scraper piston completes the reset action under compressed air, the compressed air can enter the air chamber from the air chamber inlet, then leave the air chamber from the air chamber outlet, and finally be discharged from the exhaust port, ensuring the smooth completion of the reset action.

[0017] 4. The present invention has a simple structure and is easy to use. Attached Figure Description

[0018] Figure 1 This is a schematic diagram of the magnetic filtering device of the present invention; Figure 2 This is a schematic diagram of the sludge scraper sleeve; Figure 3 This is a cross-sectional structural diagram of the mud scraper sleeve; Figure 4 This is a structural schematic diagram of the right connector; Figure 5 This is a structural schematic diagram of the left connector; Figure 6 This is a schematic diagram of the buffer device. Figure 7 This is a schematic diagram of the buffer ring structure; Wherein: 1-Outer shell; 2-Magnetic rod; 3-Outer shell connector; 4-Inlet; 5-Outlet; 6-Sludge discharge port; 7-Left end cap; 8-Left fixing plate; 9-Sludge scraping air inlet; 10-Exhaust port; 11-Sludge scraping piston; 12-Right end cap; 13-Right fixing plate; 14-Piston reset air inlet; 15-Buffer device; 16-Left connector; 17-Right connector; 21-Air chamber outlet; 22-Air chamber; 23-Air chamber inlet; 24-Left... Magnetic rod connecting rod; 25-Left air inlet sleeve; 26-Right air inlet sleeve; 27-Right magnetic rod connecting rod; 28-Air passage; 30-Left scraper sleeve; 31-Right scraper sleeve; 32-Scraper connecting sleeve; 33-Outer sealing ring; 34-Inner sealing ring; 35-Pressure sensor; 36-Spring; 37-Guide sleeve; 38-Buffer ring; 39-Right connector magnetic rod connector head; 40-Right connector connecting rod; 41-Right connector fixing joint. Detailed Implementation

[0019] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be described in detail below with reference to the accompanying drawings. It should be understood that the specific embodiments described herein are for illustrative purposes only and are not intended to limit the invention. All other embodiments obtained by those skilled in the art based on the embodiments of this invention without inventive effort are within the scope of protection of this invention.

[0020] Example 1: like Figure 1 As shown, a magnetic filtration device for cold rolling wastewater includes a housing 1. Inside the housing 1, a left connector 16, a magnetic rod 2, and a right connector 17 are arranged in sequence. The left connector 16, the magnetic rod 2, and the right connector 17 are all cylindrical and have the same outer diameter.

[0021] The outer casing 1 includes a left outer casing and a right outer casing. The left outer casing and the right outer casing are connected by an outer casing connector 3. The left end port of the outer casing 1 is provided with a left end cover 7. The left end of the left air intake sleeve 25 passes through the left end cover 7 in a sealed manner and then passes through the left fixing plate 8 and is fixedly connected to the left fixing plate 8 (e.g., by welding). The right end port of the outer casing 1 is provided with a right end cover 12. The right end of the right air intake sleeve 26 passes through the right end cover 12 in a sealed manner and then passes through the right fixing plate 13 and is fixedly connected to the right fixing plate 13, thereby fixing the outer casing 1.

[0022] The right end of the left magnetic rod connecting rod 24 passes through the left air intake sleeve 25 and is threaded to the left end of the left connector 16. The left end of the left magnetic rod connecting rod 24 is screwed into a nut, and the nut is pressed against the left side of the left fixing plate 8. The left end of the right magnetic rod connecting rod 27 passes through the right air intake sleeve 26 and is threaded to the right end of the right connector 17. The right end of the right magnetic rod connecting rod 27 is screwed into a nut, and the nut is pressed against the right side of the right fixing plate 13, thereby fixing the left connector 16, the magnetic rod 2, and the right connector 17.

[0023] The outer casing 1 is equipped with an inlet 4, an outlet 5, and a sludge discharge port 6. The inlet 4 is located below the left end of the magnetic rod 2, and the outlet 5 is located above the right end of the magnetic rod 2. The gap between the magnetic rod 2 and the outer casing 1 forms a flow channel. By setting the inlet at the bottom and the outlet at the top, the wastewater to be treated will fill the flow channel before flowing out from the outlet 5, which increases the filtration time of the wastewater to be treated that first enters the outer casing 1 and improves the filtration effect. The sludge discharge port 6 is located below the right connector 17.

[0024] The left intake sleeve 25 is provided with a mud scraping air inlet 9, and the right intake sleeve 26 is provided with a piston reset air inlet 14; when compressed air is connected to the mud scraping air inlet 9 or the piston reset air inlet 14, compressed air can be filled into the outer casing 1.

[0025] As a feasible preferred solution, sealing rings are fitted on both the left magnetic rod connecting rod 24 and the right magnetic rod connecting rod 27. The sealing ring fitted on the left magnetic rod connecting rod 24 is located to the left of the mud scraping air inlet 9 to prevent gas from leaking from the left air inlet sleeve 25, and the sealing ring fitted on the right magnetic rod connecting rod 27 is located to the right of the piston reset air inlet 14 to prevent gas from leaking from the right air inlet sleeve 26.

[0026] A scraper piston 11 is fitted onto the magnetic rod 2. The inner wall of the scraper piston 11 is in contact with the outer wall of the magnetic rod 2. When the scraper piston 11 slides inside the outer shell 1, it is used to scrape off the deposits on the outer wall of the magnetic rod 2. When the scraper piston 11 slides inside the outer shell 1, it is used to scrape off the deposits on the inner wall of the outer shell 1. When the scraper piston 11 is connected to compressed air through the scraper air inlet 9 or the piston return air inlet 14, it slides on the left connector 16, the magnetic rod 2 and the right connector 17, thereby completing the scraping action.

[0027] like Figure 2 and Figure 3 As shown, the scraper piston 11 includes a left scraper sleeve 30, a scraper connecting sleeve 32, and a right scraper sleeve 31 connected in sequence. Both the left and right scraper sleeves 30 and 31 have outer annular grooves on their outer walls, and an outer sealing ring 33 is fitted into these grooves. The outer ring wall of the outer sealing ring 33 slides in contact with the inner wall of the outer casing 1, and also serves as a dynamic seal. Both the left and right scraper sleeves 30 and 31 have inner annular grooves on their inner walls, and an inner sealing ring 34 is fitted into these grooves. The inner ring wall of the inner sealing ring 34 slides in contact with the outer wall of the magnetic rod 2, and also serves as a dynamic seal. The outer sealing ring 33 and the inner sealing ring 34 seal the flow passage, and the scraper piston 11 can slide on the magnetic rod 2 under the action of compressed air.

[0028] When compressed air is connected to the sludge scraping air inlet 9, the sludge scraping piston 11 moves along the direction from the left connector 16 to the right connector 17 on the magnetic rod 2. Since the outer diameter of the magnetic rod 2 is the same as the outer diameter of the right connector 17, the sludge scraping piston 11 will move to the state of being sleeved on the right connector 17, completing the sludge scraping action. When compressed air is connected to the piston reset air inlet 14, the sludge scraping piston 11 moves along the direction from the right connector 17 to the left connector 16 on the right connector 17 and the magnetic rod 2. Since the outer diameter of the magnetic rod 2 is the same as the outer diameter of the left connector 16, the sludge scraping piston 11 will move to the state of being sleeved on the left connector 16, completing the reset action of the sludge scraping piston 11.

[0029] like Figure 4As shown, the right connector 17 includes a right connector fixing joint 41, a right connector connecting rod 40, and a right connector magnetic rod connector 39 connected in sequence. The right connector fixing joint 41 is connected to the right connector magnetic rod connector 39 through the right connector connecting rod 40. The right connector fixing joint 41 is threaded to the left end of the right magnetic rod connecting rod 27. The right connector magnetic rod connector 39 is fixedly connected to the magnetic rod 2 (an internal thread interface is provided at the right end of the magnetic rod 2, and an external thread connecting bolt is provided on the left side of the right connector magnetic rod connector 39. The external thread connecting bolt and the internal thread interface are threaded to fix the magnetic rod 2 to the right connector magnetic rod connector 39).

[0030] The right connecting rod 40 consists of multiple rods evenly distributed at circumferential intervals. Both ends of the right connecting rod 40 are fixedly connected to the right connecting fixed joint 41 and the right connecting magnetic rod connector 39, respectively. In this embodiment, the number of right connecting rods 40 is 12 to 16. The central axis of the distribution circle of the right connecting rods 40 is parallel to the central axis of the right connecting fixed joint 41. Since the right connecting rods 40 are evenly distributed at circumferential intervals, the iron powder in the flow channel will fall from the gap between the right connecting rods 40 during the sludge scraping process and will eventually be discharged from the sludge discharge port 6.

[0031] like Figure 5 As shown, the left connector 16 has a hollow interior forming an air chamber 22. The sidewall of the left connector 16 has circumferentially distributed air chamber inlets 23, and the left end face of the left connector 16 has an air chamber outlet 21. The right end of the left connector 16 is connected to the magnetic rod 2 (an internal thread interface is provided at the left end of the magnetic rod 2, and an external thread connecting bolt is provided at the right end face of the left connector 16; the external thread connecting bolt and the internal thread interface are connected by threads to fix the magnetic rod 2 to the right end of the left connector 16). In this embodiment, the distance between the central axis of the air chamber outlet 21 and the central axis of the left end face of the left connector 16 is half the diameter of the left end face of the left connector 16. The air chamber inlets 23 are close to the magnetic rod 2, and there are 4 to 6 air chamber inlets 23 evenly distributed circumferentially.

[0032] Furthermore, an exhaust port 10 is provided on the outer casing 1, which is located on the left side of the left connector 16. When compressed air is introduced from the piston reset inlet port 14, the compressed air enters the air chamber 22 from the air chamber inlet port 23, then leaves the air chamber from the air chamber outlet port 21, and finally leaves the outer casing 1 from the exhaust port 10.

[0033] Since the scraper piston 11 moves under the action of compressed air, in order to avoid the scraper piston 11 impacting both ends of the outer casing 1, buffer devices 15 are provided on the inner walls of both the left end cover 7 and the right end cover 12. The buffer devices 15 provided on the inner walls of the left end cover 7 and the right end cover 12 are defined as the left buffer device and the right buffer device, respectively. Figure 6 and Figure 7 As shown, both the left and right buffer devices include a pressure sensor 35, a spring 36, a guide sleeve 37, and a buffer ring 38 connected in sequence. The buffer ring 38 has uniform air passages 28, the area of ​​which is 10-15% of the buffer ring 38's area. The buffer ring 38 increases the contact area between the buffer device 15 and the scraper piston 11, resulting in better buffering. Simultaneously, the air passages 28 on the buffer ring 38 do not affect the compressed air's pushing effect on the scraper piston 11. The pressure sensor 35 of the left buffer device is located inside the left end cap 7, and the buffer ring 38 and guide sleeve 37 of the left buffer device are fitted onto the left end of the left connector 16. The pressure sensor 35 of the right buffer device is located inside the right end cap 12, and the buffer ring 38 and guide sleeve 37 of the right buffer device are fitted onto the right end of the right connector 17.

[0034] As a feasible preferred solution, when the spring 36 of the left buffer device is in its natural state and the buffer ring 38 is connected to the scraper piston 11, the right scraper sleeve 31 of the scraper piston 11, which is sleeved on the left connector 16, is located at the air inlet 23 of the air chamber. At this time, the air inlet 23 of the air chamber is blocked by the right scraper sleeve 31, and compressed air cannot flow from the air chamber 22. When the spring 36 of the right buffer device is in its natural state and the buffer ring 38 is connected to the scraper piston 11, the left scraper sleeve 30 of the scraper piston 11, which is sleeved on the left end of the right connector 17, is located at the magnetic rod connector 39 of the right connector. In this state, the compressed air entering from the piston reset air inlet 14 is blocked by the scraper piston 11 and will not flow directly from the flow channel. Under the action of the compressed air entering from the piston reset air inlet 14, the scraper piston 11 slides to the left.

[0035] As a feasible preferred embodiment, the central axes of the left end cap 7, right end cap 12, outer shell 1, left air intake sleeve 25, right air intake sleeve 26, left magnetic rod connecting rod 24, right magnetic rod connecting rod 27, left fixing plate 8 and right fixing plate 13 coincide.

[0036] As a feasible preferred solution, electric valves are installed on the connecting pipes of piston reset air inlet 14, exhaust port 10 and sludge scraper air inlet 9. The opening and closing of the corresponding pipes are achieved by controlling the opening and closing of the electric valves. Pneumatic valves are installed on the connecting pipes of water inlet 4, water outlet 5 and sludge discharge port 6. The opening and closing of the corresponding pipes are achieved by controlling the opening and closing of the pneumatic valves.

[0037] In this embodiment, the magnetic induction intensity on the surface of the magnetic rod 2 is >3500Gs, the gap between the magnetic rod 2 and the outer shell 1 is 2~4cm, the diameter of the magnetic rod 2 is 5~10cm, the length of the magnetic rod is 80~120cm, the outer shell of the magnetic rod 2 is made of stainless steel, and the surface is polished to a polishing level of five to ensure the smoothness of the surface.

[0038] As a feasible preferred solution, pressure gauges are installed on the connecting pipes of inlet 4 and outlet 5. When too much iron powder is adsorbed on the surface of magnetic rod 2, the wastewater flow channel will narrow, and the pressure difference between inlet 4 and outlet 5 will increase. The pressure difference between the connecting pipes of inlet 4 and outlet 5 is set to be controlled below 0.05 MPa. When the pressure difference between the connecting pipes of inlet 4 and outlet 5 reaches 0.05 MPa, the sludge scraping action is started to prevent the magnetic filter device from becoming clogged.

[0039] When the present invention completes the reset action of the scraper piston 11, compressed air is introduced from the piston reset air inlet 14. The compressed air enters the interior of the outer shell 1 through the piston reset air inlet 14 and the gap between the right air inlet sleeve 26 and the right magnetic rod connecting rod 27. Then, it acts on the right scraper sleeve 31 through the air passage 28 and the gap between the buffer ring 38 and the outer shell 1. The scraper piston 11 moves to the left under the pushing action of the compressed air. When the scraper piston 11 contacts the left buffer device, the spring 36 in the left buffer device is in the natural state. The right scraper sleeve 31 covers the air chamber inlet 23. With the spring 36 in the left buffer device... As the compression occurs, the right scraper sleeve 31 passes over the air chamber inlet 23 and is located to the left of the air chamber inlet 23. Compressed air enters the air chamber 22 from the air chamber inlet 23, then leaves the air chamber 22 from the air chamber outlet 21, and finally flows out from the exhaust port 10. As the compressed air flows out from the exhaust port 10, the thrust of the compressed air on the scraper piston 11 will decrease rapidly. When the force of the spring 36 in the left buffer device on the scraper piston 11 is balanced with the thrust of the compressed air on the scraper piston 11, the value of the pressure sensor 35 in the left buffer device is stable. Then, the electric valve on the connecting pipe of the piston reset air inlet 14 is slowly closed. During the closing of the electric valve on the connecting pipe of the piston reset air inlet 14, the thrust of compressed air on the scraper piston 11 continuously decreases. The force exerted by the spring 36 in the left buffer device on the moving scraper piston 11 is greater than the thrust of compressed air on the scraper piston 11, causing the scraper piston 11 to move to the right. The right scraper sleeve 31 covers part of the air chamber inlet 23 (i.e., the ventilation area of ​​the air chamber inlet 23 will decrease), and the flow rate of compressed air will decrease. At this time, the thrust of compressed air on the scraper piston 11 will stop decreasing. As the spring 36 in the left buffer device rebounds, the left buffer device... The force exerted by the spring 36 on the sludge scraper piston 11 also decreases. The force exerted by the spring 36 on the sludge scraper piston 11 in the left buffer device and the thrust of the compressed air on the sludge scraper piston 11 return to equilibrium. The sludge scraper piston 11 stops moving to the right. As the electric valve on the connecting pipe of the piston reset air inlet 14 slowly closes, the sludge scraper piston 11 slowly moves to the right. When the electric valve on the connecting pipe of the piston reset air inlet 14 is completely closed, the right sludge scraper sleeve 31 covers the air chamber air inlet 23 and the right sludge scraper sleeve 31 is located to the left of the water inlet 4, thus completing the reset of the sludge scraper piston 11.

[0040] During magnetic filtration, cold-rolled wastewater enters the outer casing 1 through the inlet 4. When the scraper piston 11 is in the reset state, the right scraper sleeve 31 covers the air chamber inlet 23 and is located to the left of the inlet 4. The right scraper sleeve 31 does not affect the water intake of the inlet 4. Since the water pressure is much lower than the compressed air pressure, the reset scraper piston 11 is always covered by the air chamber inlet 23 under the action of the spring 36 in the left buffer device. The air chamber inlet 23 is covered by the right scraper sleeve 31, so the cold-rolled wastewater will not enter the air chamber 22. The cold-rolled wastewater flows along the flow channel and finally flows out from the outlet 5.

[0041] When the scraping piston 11 completes its scraping action, compressed air is introduced into the scraping air inlet 9. The compressed air passes through the gap between the air chamber inlet 23 and the left magnetic rod connecting rod 24, the air chamber outlet 21, the air chamber 22, and the air chamber inlet 23 in sequence, and enters the gap between the magnetic rod 2 and the outer shell 1. It acts on the left side of the scraping piston 11 and pushes the scraping piston 11 to slide to the right. The scraped iron powder is discharged from the gap of the right connecting rod 40 and the mud discharge port 6. When the scraper piston 11 moves to contact the right buffer device, the left scraper sleeve 30 of the scraper piston 11 is just located on the right connector magnetic rod connector 39. When the scraper piston 11 continues to move to the right, the left scraper sleeve 30 will pass over the right connector magnetic rod connector 39. Compressed air flows out from the mud discharge port 6 after passing through the gap between the right connector connecting rods 40. The thrust of the compressed air on the scraper piston 11 decreases as the compressed air is discharged. The force of the spring 36 in the right buffer device on the scraper piston 11 gradually reaches a balance with the force of the compressed air on the scraper piston 11. At this time, the pressure value of the pressure sensor 35 in the right buffer device is in a stable state. The corresponding connecting pipes of the scraper air inlet 9 and the mud discharge port 6 are closed. When the scraper air inlet 9 stops receiving compressed air, the spring 36 in the right buffer device is in a natural state, and the left scraper sleeve 30 is located at the right connector magnetic rod connector 39.

[0042] Example 2: A method for using a magnetic filtration device for cold rolling wastewater, utilizing the magnetic filtration device described in Example 1, includes the following steps: Step 1: Connect the corresponding connecting pipes of piston reset air inlet 14 and exhaust port 10, disconnect the corresponding connecting pipes of water inlet 4, water outlet 5, sludge discharge port 6 and sludge scraping air inlet 9, introduce compressed air through piston reset air inlet 14, push sludge scraping piston 11 to buffer device 15 set on left end cover 7, sludge scraping piston 11 completes reset under the combined action of buffer device 15 and compressed air, after sludge scraping piston 11 resets, disconnect the corresponding connecting pipes of piston reset air inlet 14 and exhaust port 10.

[0043] Specifically, compressed air is introduced into the piston reset inlet 14. The pressure of the compressed air is 0.4~0.5 MPa. The compressed air enters the interior of the outer shell 1 through the piston reset inlet 14 and the gap between the right inlet sleeve 26 and the right magnetic rod connecting rod 27. Then, it acts on the right scraper sleeve 31 through the air passage 28 and the gap between the buffer ring 38 and the outer shell 1. The scraper piston 11 moves to the left under the push of the compressed air. When the scraper piston 11 hits the left buffer device, the spring 36 in the left buffer device is in the natural state. The right scraper sleeve 31 covers the air chamber inlet 23. As the spring 36 in the left buffer device contracts, the right scraper sleeve 31 passes over the air chamber inlet 23 and is located to the left of the air chamber inlet 23. At this time, the compressed air enters the air chamber 22 from the air chamber inlet 23, then leaves the air chamber 22 from the air chamber outlet 21, and finally flows out from the exhaust port 10. As compressed air flows out of exhaust port 10, the thrust of the compressed air on the scraper piston 11 decreases rapidly. When the force exerted by the spring 36 in the left buffer device on the scraper piston 11 balances with the thrust of the compressed air on the scraper piston 11, the value of the pressure sensor 35 in the left buffer device stabilizes. At this time, the electric valve on the connecting pipe of the piston reset air inlet 14 is slowly closed. During the closing process of the electric valve on the connecting pipe of the piston reset air inlet 14, the thrust of the compressed air on the scraper piston 11 continuously decreases. The force exerted by the spring 36 in the left buffer device on the moving scraper piston 11 is greater than the thrust of the compressed air on the scraper piston 11, and the scraper piston 11 moves to the right. The right scraper sleeve 31 covers part of the air chamber inlet 23 (i.e., the ventilation area of ​​the air chamber inlet 23 decreases), and the flow rate of compressed air decreases. At this time, the thrust of the compressed air on the scraper piston 11 stops decreasing. As the spring 36 in the left buffer device rebounds, the spring 36 in the left buffer device exerts a force on the scraper piston 11... The force of piston 11 also decreases, and the force of spring 36 in the left buffer device on the sludge scraping piston 11 and the thrust of compressed air on the sludge scraping piston 11 return to equilibrium. The sludge scraping piston 11 stops moving to the right. As the electric valve on the connecting pipe of piston reset air inlet 14 slowly closes, the sludge scraping piston 11 slowly moves to the right. When the electric valve on the connecting pipe of piston reset air inlet 14 is completely closed, spring 36 in the left buffer device returns to its natural state. Right sludge scraping sleeve 31 covers air chamber air inlet 23 and is located to the left of water inlet 4, completing the reset of sludge scraping piston 11.

[0044] Step 2: Connect the corresponding pipes of inlet 4 and outlet 5. The cold rolling wastewater enters the outer shell 1 from inlet 4, flows through the flow channel and flows out from outlet 5, thus completing the filtration of the cold rolling wastewater.

[0045] Specifically, after the cold rolling wastewater enters the outer shell 1, it flows over the surface of the magnetic rod 2. The magnetic rod 2 surface undergoes adsorption, adsorbing the magnetic substances in the cold rolling wastewater onto the surface of the magnetic rod 2. After adsorption treatment, the cold rolling wastewater flows out of the outlet 5 of the magnetic filter device, completing the filtration of the cold rolling wastewater.

[0046] It should be noted that when the scraper piston 11 is in the reset state, the right scraper sleeve 31 covers the air inlet 23 of the air chamber and is located to the left of the water inlet 4. The right scraper sleeve 31 will not affect the water intake of the water inlet 4. When water enters the water inlet 4, the water pressure is much lower than the pressure of compressed air. Under the action of the spring 36 in the left buffer device, the scraper piston 11 in the reset state always covers the air inlet 23 of the air chamber. The air inlet 23 of the air chamber is covered by the right scraper sleeve 31, so the cold rolling wastewater will not enter the air chamber 22. The cold rolling wastewater flows along the flow channel and finally flows out from the outlet 5.

[0047] Step 3: When the pressure difference between the inlet 4 and the outlet 5 reaches the set threshold (in this embodiment, the set threshold is 0.05 MPa), the corresponding connecting pipes of the inlet 4 and the outlet 5 are cut off, and the corresponding connecting pipes of the sludge scraper air inlet 9 and the sludge discharge outlet 6 are connected. Compressed air enters the outer shell 1 from the sludge scraper air inlet 9, pushing the sludge scraper piston 11 to move from left to right. The iron powder adsorbed on the magnetic rod 2 moves from left to right under the action of the sludge scraper piston 11. When the right sludge scraper sleeve 31 passes the right connecting member fixed joint 41, the sludge scraping action is completed. When the pressure value of the pressure sensor 35 in the right buffer device is stable, the corresponding connecting pipes of the sludge scraper air inlet 9 and the sludge discharge outlet 6 are closed.

[0048] Specifically, during the sludge scraping process, compressed air is introduced into the sludge scraping air inlet 9. The compressed air passes through the gap between the air chamber inlet 23 and the left magnetic rod connecting rod 24, the air chamber outlet 21, the air chamber 22, and the air chamber inlet 23 in sequence, and enters the gap between the magnetic rod 2 and the outer shell 1. It acts on the left side of the sludge scraping piston 11 and pushes the sludge scraping piston 11 to slide to the right. When the right sludge scraping sleeve 31 passes the right connecting part magnetic rod connecting head 39, the scraped iron powder is discharged from the gap of the right connecting part connecting rod 40 and the sludge discharge port 6.

[0049] When the scraper piston 11 continues to move to the right and contacts the right buffer device, the left scraper sleeve 30 of the scraper piston 11 is just located on the magnetic rod connector 39 of the right connector. When the scraper piston 11 continues to move to the right, the left scraper sleeve 30 will pass over the magnetic rod connector 39 of the right connector. Compressed air flows out from the mud discharge port 6 after passing through the gap between the connecting rods 40 of the right connector. The thrust of the compressed air on the scraper piston 11 decreases as the compressed air is discharged. The force of the spring 36 in the right buffer device on the scraper piston 11 gradually reaches a balance with the thrust of the compressed air on the scraper piston 11. At this time, when the pressure value of the pressure sensor 35 in the right buffer device is stable, the corresponding connecting pipes of the scraper air inlet 9 and the mud discharge port 6 are closed.

[0050] It should be noted that when the air inlet 9 for scraping mud stops receiving compressed air, the spring 36 of the right buffer device is in its natural state, and the left scraping sleeve 30 is in the position of the magnetic rod connector 39 of the right connector. When the scraping piston 11 is reset next time, the compressed air will not flow directly from the gap between the magnetic rod 2 and the outer shell 1, but will first act on the scraping piston 11, pushing the scraping piston 11 to move to the left.

[0051] Step 4: Repeat steps 1 to 3 to complete the next cold rolling wastewater treatment.

[0052] Specifically, after the sludge scraping is completed, the sludge scraping piston 11 is pushed to the left to reset, and the corresponding connecting pipes of the inlet 4 and outlet 5 are reconnected to continue treating the cold rolling wastewater. The iron powder discharged during the sludge scraping process and the wastewater in the outer casing 1 are discharged from the sludge discharge port 6 together with the wastewater in the outer casing 1.

[0053] In this embodiment, the corresponding connecting pipe of the sludge discharge port 6 is first opened to discharge the wastewater in the outer casing 1 before sludge scraping is performed. Specifically, the corresponding connecting pipes of the sludge discharge port 6 and the piston reset air inlet 14 are first opened, and the opening time is set to 30 seconds. Then, the corresponding connecting pipe of the piston reset air inlet 14 is cut off, and the corresponding connecting pipe of the sludge scraping air inlet 9 is opened to discharge sludge.

[0054] Example 3: Wastewater from the finishing mill in a cold rolling mill was selected as the treatment target of this invention. The above embodiments were implemented, with a suspended solids content of 50-100 mg / L and a treatment flow rate of 10 m³ / L. 3 / h.

[0055] The magnetic induction intensity on the surface of magnetic rod 2 is 4000 Gs, the gap between magnetic rod 2 and outer shell 1 is 3 cm, the diameter of magnetic rod 2 is 6 cm, and the length of magnetic rod is 120 cm. The number of magnetic filter devices described in Example 1 is 8 sets, using a mode of operation where 4 sets are connected in parallel as one stage and two stages are connected in series.

[0056] A wastewater filtration cycle is set to 60 minutes. After 60 minutes, the four sets of magnetic filtration devices take turns scraping sludge. After treatment by the magnetic filtration devices, the concentration of suspended solids in the effluent is less than 20 mg / L.

[0057] When magnetic filtration devices are arranged in parallel, the treatment efficiency of cold rolling wastewater can be improved; when magnetic filtration devices are arranged in series, the treatment effect of cold rolling wastewater can be improved.

[0058] The magnetic filtration device of this invention can effectively remove iron powder from wastewater. The equipment has a small footprint, stable treatment effect, and high degree of automation.

[0059] Finally, it should be noted that the above specific embodiments are only used to illustrate the technical solutions of the present invention and not to limit it. Although the present invention has been described in detail, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the spirit and scope of the technical solutions of the present invention, and all such modifications or substitutions should be covered within the scope of the claims of the present invention.

Claims

1. A magnetic filtering device for cold rolling wastewater comprising a housing (1), characterized in that, The left end cover (7) and the right end cover (12) are arranged at two ends of the shell (1) respectively, the right end of the left air inlet sleeve (25) penetrates the left end cover (7) sealingly, the left air inlet sleeve (25) is provided with a mud scraping air inlet (9), the left end of the right air inlet sleeve (26) penetrates the right end cover (12) sealingly, and the right air inlet sleeve (26) is provided with a piston reset air inlet (14); the shell (1) is internally provided with the left connecting piece (16), the magnetic rod (2) and the right connecting piece (17) which have the same outer diameter and are sequentially connected, the shell (1) is provided with a water inlet (4), a water outlet (5), a mud discharge port (6) and an exhaust port (10), the water inlet (4) and the water outlet (5) are respectively located at two ends of the magnetic rod (2) and the water outlet (5) is above the water inlet (4), the mud discharge port (6) is below the right connecting piece (17), and the exhaust port (10) is left of the left connecting piece (16); the mud scraping piston (11) is sleeved on the magnetic rod (2), the inner wall of the mud scraping piston (11) is in sliding fit with the outer wall of the magnetic rod (2), the outer wall of the mud scraping piston (11) is in sliding fit with the inner wall of the shell (1) and keeps contact to scrape off the adhering objects.

2. A magnetic filtration device for cold rolling wastewater as claimed in claim 1, wherein, The left magnetic rod connecting rod (24) and the right magnetic rod connecting rod (27) are further included, the right end of the left magnetic rod connecting rod (24) penetrates the left air inlet sleeve (25) and is threadedly connected with the left end of the left connecting piece (16), the left end of the left magnetic rod connecting rod (24) is screwed into a nut and the nut is pressed against the left side of the left fixed plate (8), the left end of the left air inlet sleeve (25) penetrates the left fixed plate (8) and is fixedly connected with the left fixed plate (8); the left end of the right magnetic rod connecting rod (27) penetrates the right air inlet sleeve (26) and is threadedly connected with the right end of the right connecting piece (17); the right end of the right magnetic rod connecting rod (27) is screwed into a nut and the nut is pressed against the right side of the right fixed plate (13), and the right end of the right air inlet sleeve (26) penetrates the right fixed plate (13) and is fixedly connected with the right fixed plate (13).

3. A magnetic filter device for cold rolling wastewater according to claim 2, characterized in that, The left magnetic rod connecting rod (24) and the right magnetic rod connecting rod (27) are further included, the right end of the left magnetic rod connecting rod (24) penetrates the left air inlet sleeve (25) and is threadedly connected with the left end of the left connecting piece (16), the left end of the left magnetic rod connecting rod (24) is screwed into a nut and the nut is pressed against the left side of the left fixed plate (8), the left end of the left air inlet sleeve (25) penetrates the left fixed plate (8) and is fixedly connected with the left fixed plate (8); the left end of the right magnetic rod connecting rod (27) penetrates the right air inlet sleeve (26) and is threadedly connected with the right end of the right connecting piece (17); the right end of the right magnetic rod connecting rod (27) is screwed into a nut and the nut is pressed against the right side of the right fixed plate (13), and the right end of the right air inlet sleeve (26) penetrates the right fixed plate (13) and is fixedly connected with the right fixed plate (13).

4. A magnetic filter device for cold rolling wastewater according to claim 2, characterized in that, The left magnetic rod connecting rod (24) and the right magnetic rod connecting rod (27) are further included, the right end of the left magnetic rod connecting rod (24) penetrates the left air inlet sleeve (25) and is threadedly connected with the left end of the left connecting piece (16), the left end of the left magnetic rod connecting rod (24) is screwed into a nut and the nut is pressed against the left side of the left fixed plate (8), the left end of the left air inlet sleeve (25) penetrates the left fixed plate (8) and is fixedly connected with the left fixed plate (8); the left end of the right magnetic rod connecting rod (27) penetrates the right air inlet sleeve (26) and is threadedly connected with the right end of the right connecting piece (17); the right end of the right magnetic rod connecting rod (27) is screwed into a nut and the nut is pressed against the right side of the right fixed plate (13), and the right end of the right air inlet sleeve (26) penetrates the right fixed plate (13) and is fixedly connected with the right fixed plate (13).

5. A magnetic filter device for cold rolling wastewater according to claim 4, characterized in that, The right connecting piece (17) comprises a right connecting piece fixed joint (41), a right connecting piece connecting rod (40) and a right connecting piece magnetic rod connecting head (39) connected in sequence, the right connecting piece magnetic rod connecting head (39) is fixedly connected with the magnetic rod (2), the right connecting piece connecting rod (40) has multiple rods and is uniformly distributed in a circle, and the right connecting piece fixed joint (41) is threadedly connected with the left end of the right magnetic rod connecting rod (27).

6. A magnetic filter device for cold rolling wastewater according to claim 5, characterized in that The left connecting piece (16) is internally hollow to form an air chamber (22), the side wall of the left connecting piece (16) is provided with air chamber air inlets (23) distributed in a circle, the left end face of the left connecting piece (16) is provided with an air chamber air outlet (21), and the right end of the left connecting piece (16) is connected with the magnetic rod (2).

7. A magnetic filter device for cold rolling wastewater according to claim 6, characterized in that The inner walls of the left side end cover (7) and the right side end cover (12) are both provided with a buffer device (15), the buffer device (15) comprises a pressure sensor (35), a spring (36), a guide sleeve (37) and a buffer ring (38) connected in sequence, the buffer devices (15) provided on the inner walls of the left side end cover (7) and the right side end cover (12) are respectively left and right buffer devices, the pressure sensor (35) of the left buffer device is arranged on the inner side of the left side end cover (7), and the buffer ring (38) and the guide sleeve (37) of the left buffer device are sleeved on the left end of the left connecting piece (16); the pressure sensor (35) of the right buffer device is arranged on the inner side of the right side end cover (12), and the buffer ring (38) and the guide sleeve (37) of the right buffer device are sleeved on the right end of the right connecting piece (17).

8. A magnetic filter device for cold rolling wastewater according to claim 7, characterized in that, The buffer ring (38) is provided with uniform air passing channels (28), and the area of the air passing channel (28) is 10-15% of the area of the buffer ring (38).

9. A magnetic filter device for cold rolling wastewater according to claim 7, characterized in that, Pressure gauges are mounted on the connecting pipelines of the water inlet (4) and the water outlet (5).

10. A method for using the magnetic filtering device for cold rolling wastewater according to claim 9, comprising the following steps: Step 1, cutting off the corresponding connecting pipelines of the water inlet (4), the water outlet (5), the sludge discharge port (6) and the sludge scraping air inlet (9), and connecting the corresponding connecting pipelines of the piston reset air inlet (14) and the exhaust port (10), introducing compressed air into the piston reset air inlet (14), and completing the reset action of the sludge scraping piston (11) under the action of the compressed air, after the reset of the sludge scraping piston (11), cutting off the corresponding connecting pipelines of the piston reset air inlet (14) and the exhaust port (10); the process of the reset action is as follows: The compressed air enters the inside of the shell (1) through the gap between the piston reset air inlet (14) and the right air inlet sleeve (26) and the right magnetic rod connecting rod (27), and then acts on the right mud scraping sleeve (31) through the gap between the air passage (28) and the buffer ring (38) and the shell (1). The mud scraping piston (11) moves to the left under the pushing action of the compressed air. When the mud scraping piston (11) contacts the left buffer device, the spring (36) in the left buffer device is in a natural state, and the right mud scraping sleeve (31) covers the air chamber air inlet (23). With the contraction of the spring (36) in the left buffer device, the right mud scraping sleeve (31) passes through the air chamber air inlet (23) and is located on the left side of the air chamber air inlet (23). The compressed air enters the air chamber (22) from the air chamber air inlet (23), and then exits the air chamber (22) from the air outlet (21), and finally flows out from the exhaust port (10). With the compressed air flowing out of the exhaust port (10), the pushing force of the compressed air on the mud scraping piston (11) will decrease rapidly, and when the force of the spring (36) in the left buffer device on the mud scraping piston (11) and the pushing force of the compressed air on the mud scraping piston (11) are balanced, the value of the pressure sensor (35) in the left buffer device is in a stable state, and then the connecting pipeline of the piston reset air inlet (14) is slowly cut off. During the slow cutting process of the connecting pipeline of the piston reset air inlet (14), the mud scraping piston (11) slowly moves to the right. When the connecting pipeline of the piston reset air inlet (14) is completely cut off, the spring (36) in the left buffer device returns to the natural state, the right mud scraping sleeve (31) covers the air chamber air inlet (23), and the right mud scraping sleeve (31) is located on the left side of the water inlet (4). The reset of the mud scraping piston (11) is completed. Step 2, turn on the corresponding connecting pipelines of the water inlet (4) and the water outlet (5), and the cold rolling wastewater enters the shell (1) from the water inlet (4) and flows out from the water outlet (5) after flowing through the flow passage, completing the filtration of the cold rolling wastewater; The specific process is as follows: When the cold rolling wastewater enters the shell (1) from the water inlet (4), the mud scraping piston (11) is in a reset state, the right mud scraping sleeve (31) covers the air chamber air inlet (23), and the right mud scraping sleeve (31) is located on the left side of the water inlet (4). The right mud scraping sleeve 3 will not affect the water inlet of the water inlet (4). Because the water pressure is much smaller than the pressure of the compressed air, the reset mud scraping piston (11) is always covered on the air chamber air inlet (23) under the action of the spring (36) in the left buffer device, and the water flow cannot enter the air chamber (22). The water flow flows along the flow passage and finally flows out from the water outlet (5); Step 3, when the pressure difference between the water inlet (4) and the water outlet (5) reaches the set threshold, the corresponding connecting pipeline of the water inlet (4) and the water outlet (5) is cut off, the corresponding connecting pipeline of the mud scraping air inlet (9) and the mud discharge port (6) is turned on, the compressed air enters the shell (1) from the mud scraping air inlet (9), the mud scraping piston (11) completes the mud scraping action under the action of the compressed air, when the pressure value of the pressure sensor (35) in the right buffer device is stable, the corresponding connecting pipeline of the mud scraping air inlet (9) and the mud discharge port (6) is closed, and the mud scraping process is as follows: The mud scraping air inlet (9) is connected to the compressed air, and the compressed air acts on the left side of the mud scraping piston (11) through the gap between the air chamber air inlet (23) and the left magnetic rod connecting rod (24), the air chamber air outlet (21), the air chamber (22), the air chamber air inlet (23) and the gap between the magnetic rod (2) and the shell (1), and pushes the mud scraping piston (11) to slide to the right. When the right scraping sleeve (31) passes through the right connecting piece magnetic rod connecting head (39), the scraped iron powder is discharged from the gap between the right connecting piece connecting rod (40) and the mud discharge port (6); the mud scraping piston (11) continues to move to the right and slows down under the action of the right buffer device, and after the left scraping sleeve (30) passes through the right connecting piece magnetic rod connecting head (39), the compressed air flows out from the mud discharge port (6) after passing through the gap between the right connecting piece connecting rod (40), the pushing force of the compressed air on the mud scraping piston (11) decreases with the discharge of the compressed air, and the force of the spring (36) in the right buffer device on the mud scraping piston (11) gradually balances with the pushing force of the compressed air on the mud scraping piston (11). At this time, the pressure value of the pressure sensor (35) in the right buffer device is in a stable state, and the corresponding connecting pipeline of the mud scraping air inlet (9) and the mud discharge port (6) is closed. Finally, the spring (36) in the right buffer device is in a natural state, and the left scraping sleeve (30) is located at the right connecting piece magnetic rod connecting head (39); Step 4, repeat steps 1 to 3 to complete the next cold rolling wastewater treatment.

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