Movable dust removing and grain screening equipment for granary

Abstract

The utility model provides a movable dedusting and grain screening device for a granary, which solves the problems that the time and labor are wasted and the efficiency is low when grains left in a large-area granary are screened after being manually concentrated. The device comprises a horizontally-arranged bottom frame, rollers are arranged at the bottom of the bottom frame, and a handrail is fixedly arranged at the top of the left side of the bottom frame; a shovel plate component is fixedly arranged at the right end of the bottom frame, and a multi-stage screening tank with an upper opening is arranged on the bottom frame. A conveying device is arranged on the bottom frame and located between the top of the multi-stage screening tank and the left end of the shovel plate component, and a first-stage screening mechanism and a second-stage screening mechanism are arranged in the multi-stage screening tank. When in use, the device can be pushed by personnel to quickly move on the ground of a granary, the shovel plate component can collect mixed grains and dust on the ground, then the conveying device can convey the collected materials into the multi-stage screening tank, and large-particle sundries, grains, small-particle sundries and dust are automatically separated and stored.

Description

Technical Field

[0001] This utility model relates to the field of grain conveying technology, and in particular to a mobile dust removal and grain screening device for grain warehouses. Background Technology

[0002] After grain is taken out of the warehouse, some grain mixed with dust will still remain on the ground. In order to clean up the dust and grain left on the ground, the existing treatment method is to collect and transport the grain mixed with dust out of the warehouse manually. After leaving the warehouse, the grain is then sieved by manual blowing or screening machine to obtain cleaner grain. However, this treatment method has the following disadvantages: (1) It is time-consuming and labor-intensive to collect and screen the grain left in a large area of ​​the warehouse manually, and the efficiency is low; (2) When collecting, transporting and screening the grain manually, a lot of dust will be generated in the warehouse, which is not good for human health. Utility Model Content

[0003] In order to solve the problem that the manual collection and screening of leftover grain in a large grain warehouse is time-consuming, labor-intensive and inefficient, the present invention proposes a mobile dust removal and grain screening device for grain warehouses.

[0004] The technical solution of this utility model is: a mobile dust removal and grain screening device for grain storage, including a horizontally arranged base frame, rollers at the bottom of the base frame, and a handrail fixedly provided on the top left side of the base frame;

[0005] A shovel plate component is fixedly installed at the right end of the base frame, and a multi-stage screening tank with an upper opening is installed on the base frame;

[0006] The base frame is equipped with a conveying device that is inclined from left to right and from top to bottom. The conveying device is located between the top of the multi-stage screening tank and the left end of the shovel plate component. The conveying device is used to convey the material falling from the left end of the shovel plate component to the upper opening of the multi-stage screening tank.

[0007] The multi-stage screening tank is equipped with a primary screening mechanism and a secondary screening mechanism. The primary screening mechanism is located above the secondary screening mechanism, and the screen aperture diameter of the primary screening mechanism is larger than that of the secondary screening mechanism. The bottom of the lowest point of the primary screening mechanism is connected to a first discharge pipe that is set at an angle downwards, and the bottom of the lowest point of the secondary screening mechanism is connected to a second discharge pipe that is set at an angle downwards.

[0008] A plurality of vertically arranged first connecting rods are fixedly connected between the primary screening mechanism and the secondary screening mechanism, and a vibration motor is fixedly mounted on one of the first connecting rods;

[0009] The lower side wall of the multi-stage screening tank is equipped with a first sealing door that can be opened and closed. The first sealing door is located below the secondary screening mechanism.

[0010] The base frame is equipped with a storage tank. The storage tank is fixedly equipped with a partition, which is used to divide the internal space of the storage tank into a miscellaneous storage bin and a grain storage bin. The miscellaneous storage bin is located above the grain storage bin. The end of the first discharge pipe away from the primary screening mechanism enters the miscellaneous storage bin, and the end of the second discharge pipe away from the secondary screening mechanism enters the grain storage bin.

[0011] The storage tank has a second and a third sealing door that can be opened and closed on its side wall. The second sealing door corresponds to the front and back of the miscellaneous storage bin, and the third sealing door corresponds to the front and back of the grain storage bin.

[0012] The base frame is equipped with a power supply box, and the handrail is equipped with a controller. The controller is electrically connected to the power supply box and is also connected to the transmission device.

[0013] Preferably, an electric material feeding device is provided on the top left side of the shovel plate component, which is used to feed the material at the left end of the shovel plate component to the conveying device.

[0014] Preferably, the shovel plate component includes an arc-shaped guide plate fixedly connected to the right end of the base frame. The center of the arc-shaped guide plate is located at the upper right of the base frame. The right end of the arc-shaped guide plate is fixedly connected to the left end of a horizontally arranged flat-bottomed guide plate. The right end of the flat-bottomed guide plate is fixedly connected to the left end of the shovel plate. The right end of the shovel plate is inclined to the lower right.

[0015] Both the front and rear sides of the arc-shaped guide plate and the flat-bottomed guide plate are fixed with vertically arranged second baffle plates;

[0016] The electric feeding device is located between the two second baffle plates.

[0017] Preferably, a first baffle plate is fixedly provided on both the front and rear sides of the shovel plate. The left end of the first baffle plate is fixedly connected to the right end of the second baffle plate, and the right end of the first baffle plate is located to the left of the right end of the shovel plate.

[0018] Preferably, the electric feeding device includes a rotating shaft rotatably connected between two second baffle plates, the central axis of the rotating shaft coincides with the center of the arc-shaped guide plate, and a plurality of feeding plates are fixedly arranged circumferentially on the circumferential side of the rotating shaft, the end of the feeding plate away from the rotating shaft can slide in contact with the right side of the arc-shaped guide plate.

[0019] A first rotary drive device is fixedly installed on one of the second baffle plates. The output shaft of the first rotary drive device is connected to one end of the rotating shaft, and the controller is connected to the first rotary drive device.

[0020] Preferably, the multi-stage screening tank is equipped with a feed hopper that is wider at the top and narrower at the bottom.

[0021] The primary screening mechanism includes a first screen, which is a conical mesh structure that is narrow at the top and wide at the bottom. A first ring plate is fixedly provided at the bottom of the first screen. The end of the first ring plate away from the first screen is fixedly connected to the inner wall of the multi-stage screening tank. A first discharge port that is open from top to bottom is provided on the first ring plate. The first discharge port is fixedly connected to the upper end of the first discharge pipe.

[0022] The secondary screening device includes a second screen, which is a conical mesh structure that is narrower at the top and wider at the bottom. The screen openings of the first screen are larger than those of the second screen. A ring-shaped second ring plate is fixedly provided at the bottom of the second screen. The end of the second ring plate away from the second screen is fixedly connected to the inner wall of the multi-stage screening tank. A second discharge port that is open from top to bottom is provided on the second ring plate and is connected to the upper end of the second discharge pipe.

[0023] The first connecting rod is fixedly connected between the first screen and the second screen.

[0024] Preferably, the base frame is equipped with a dust collection device, the air inlet of the dust collection device is connected to the first dust collection port and the second dust collection port by pipes, and the exhaust port of the dust collection device is connected to the dust discharge pipe.

[0025] The multi-stage screening tank has two dust discharge ports spaced apart vertically. The first dust suction port is fixedly embedded in the upper dust discharge port, and the second dust suction port is fixedly embedded in the lower dust discharge port. The other end of the dust discharge pipe, away from the dust suction device, passes into the multi-stage screening tank and is located below the secondary screening mechanism.

[0026] Advantages of this invention: When in use, this device can be moved quickly on the ground of the grain warehouse by personnel. The shovel plate component can collect the mixed grain and dust on the ground. Then, the conveying device can convey the collected material to the multi-stage screening tank. After passing through the primary screening mechanism and the secondary screening mechanism, large particles, grain, small particles and dust are automatically separated and stored, which saves time and labor and improves the efficiency of grain collection and screening. Attached Figure Description

[0027] To more clearly illustrate the technical solutions in the embodiments of this utility model or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this utility model. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0028] Figure 1 This is a schematic diagram of the main structure of Example 1;

[0029] Figure 2 for Figure 1A schematic diagram of the internal structure of the multi-stage screening tank and storage tank in the middle;

[0030] In the diagram, 1. Base frame, 2. Roller, 3. Handrail, 4. Arc-shaped guide plate, 5. Flat-bottomed guide plate, 6. Shovel plate, 7. First baffle plate, 8. Second baffle plate, 9. Rotating shaft, 10. Pushing plate, 11. First rotary drive device, 12. Conveying device, 13. Multi-stage screening tank, 14. Discharge hopper, 15. First screen, 16. First ring plate, 17. First discharge pipe, 18. Second screen, 19. 20. Second ring plate, 21. Second discharge pipe, 22. First connecting rod, 23. Vibration motor, 24. First sealing door, 25. Storage tank, 26. Partition, 27. Miscellaneous storage bin, 28. Grain storage bin, 29. Second sealing door, 30. Third sealing door, 31. Dust collection device, 32. First dust collection port, 33. Second dust collection port, 34. Dust discharge pipe, 35. Power supply box, 36. Second bracket, 37. Controller. Detailed Implementation

[0031] The technical solutions of the present utility model will be clearly and completely described below with reference to the accompanying drawings of the embodiments. Obviously, the described embodiments are only some embodiments of the present utility model, and not all embodiments. Based on the embodiments of the present utility model, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the protection scope of the present utility model.

[0032] Example 1: A mobile dust removal and grain screening device for grain storage, such as... Figure 1 As shown, it includes a horizontally arranged base frame 1, with rollers 2 at the bottom of the base frame 1 and a handrail 3 fixedly installed on the top left side of the base frame 1. A multi-stage screening tank 13 with an open top is provided on the base frame 1.

[0033] A shovel plate component is fixedly installed at the right end of the base frame 1, such as... Figure 1 As shown, the shovel plate component includes an arc-shaped guide plate 4 fixedly connected to the right end of the base frame 1. The center of the arc-shaped guide plate 4 is located at the upper right of the base frame 1. The right end of the arc-shaped guide plate 4 is fixedly connected to the left end of the horizontally arranged flat bottom guide plate 5. The right end of the flat bottom guide plate 5 is fixedly connected to the left end of the shovel plate 6. The right end of the shovel plate 6 is inclined to the lower right.

[0034] To prevent materials from falling from the front and back sides, such as Figure 1 As shown, the arc-shaped guide plate 4 and the flat bottom guide plate 5 are both fixed with vertically arranged second baffle plates 8; the front and rear sides of the shovel plate 6 are both fixed with vertically arranged first baffle plates 7, the left end of the first baffle plate 7 is fixedly connected to the right end of the second baffle plate 8, and the right end of the first baffle plate 7 is located to the left of the right end of the shovel plate 6.

[0035] An electric material-pushing device is provided between the two second baffle plates 8. This device is used to move the material from the left end of the shovel plate component onto the conveying device 12. Specifically, as shown... Figure 1 As shown, the electric feeding device includes a rotating shaft 9 rotatably connected between two second baffle plates 8. The central axis of the rotating shaft 9 coincides with the center of the arc-shaped guide plate 4. Multiple circumferentially spaced feeding plates 10 are fixedly arranged on the circumferential side of the rotating shaft 9. The end of each feeding plate 10 away from the rotating shaft 9 can slide in contact with the right side of the arc-shaped guide plate 4. A first rotary drive device 11 is fixedly mounted on one of the second baffle plates 8. The output shaft of the first rotary drive device 11 is connected to one end of the rotating shaft 9. A controller 36 is connected to the first rotary drive device 11 for control. In this embodiment, the first rotary drive device 11 is a geared motor.

[0036] A conveying device 12 is provided on the base frame 1, inclined from left to right and from top to bottom. The conveying device 12 is located between the top of the multi-stage screening tank 13 and the left end of the shovel plate component. The conveying device 12 is used to convey the material falling from the left end of the shovel plate component to the upper opening of the multi-stage screening tank 13. Specifically, the conveying device 12 includes a first bracket fixed on the base frame 1 and a second bracket fixed on the multi-stage screening tank 13. A first guide roller is rotatably mounted on the first bracket, and a first rotary drive device is fixed on the first bracket. The output shaft of the first rotary drive device is connected to one end of the first guide roller through a coupling. In this embodiment, the first rotary drive device is a geared motor. A second guide roller is rotatably mounted on the second bracket, and a conveyor belt is wound between the first guide roller and the second guide roller.

[0037] like Figure 2 As shown, the multi-stage screening tank 13 is provided with a feeding hopper 14, a primary screening mechanism, and a secondary screening mechanism in sequence from top to bottom. The feeding hopper 14 is a conical hopper structure that is wider at the top and narrower at the bottom. The primary screening mechanism includes a first screen 15, which is used to separate grain from large particles larger than the grain size. The first screen 15 is a conical mesh structure that is narrower at the top and wider at the bottom. A first annular plate 16 is fixedly provided at the bottom of the first screen 15. The end of the first annular plate 16 away from the first screen 15 is fixedly connected to the inner wall of the multi-stage screening tank 13. A first discharge port that is open from top to bottom is opened on the first annular plate 16 and is fixedly connected to the upper end of a first discharge pipe 17 that is set at an angle downward.

[0038] The secondary screening device includes a second screen 18, which is used to separate grain from small particles or dust smaller than grain. The second screen 18 has a conical mesh structure that is narrower at the top and wider at the bottom. The screen holes of the first screen 15 are larger than those of the second screen 18. A ring-shaped second ring plate 19 is fixedly provided at the bottom of the second screen 18. The end of the second ring plate 19 away from the second screen 18 is fixedly connected to the inner wall of the multi-stage screening tank 13. A second discharge port that is open from top to bottom is provided on the second ring plate 19. The second discharge port is connected to the upper end of the second discharge pipe 20 that is set at an angle downward.

[0039] A plurality of vertically arranged first connecting rods 21 are fixedly connected between the first screen 15 and the second screen 18, and a vibration motor 22 is fixedly mounted on one of the first connecting rods 21.

[0040] To facilitate the subsequent cleaning of dust accumulated at the bottom of the multi-stage screening tank 13, a first sealing door 23 that can be opened and closed is provided on the lower part of the side wall of the multi-stage screening tank 13. The first sealing door 23 is located below the secondary screening mechanism.

[0041] A storage tank 24 is mounted on the base frame 1. A partition 25 is fixedly installed inside the storage tank 24, dividing its internal space into a miscellaneous storage bin 26 and a grain storage bin 27. The miscellaneous storage bin 26 is located above the grain storage bin 27. The end of the first discharge pipe 17 furthest from the primary screening mechanism enters the miscellaneous storage bin 26. The end of the second discharge pipe 20 furthest from the secondary screening mechanism enters the grain storage bin 27. A second sealing door 28 and a third sealing door 29, which can be opened and closed, are provided on the side wall of the storage tank 24. The second sealing door 28 corresponds to the miscellaneous storage bin 26 front to back, and the third sealing door 29 corresponds to the grain storage bin 27 front to back.

[0042] To prevent dust inside the multi-stage screening tank 13 from rising excessively during vibration and overflowing from the discharge hopper 14, thus polluting the surrounding air, such as... Figure 1 and Figure 2 As shown, a dust collection device 30 is provided on the base frame 1. The air inlet of the dust collection device 30 is connected to the first dust collection port 31 and the second dust collection port 32 by pipes. The exhaust port of the dust collection device 30 is connected to the dust discharge pipe 33. The dust collection device 30 is a common vacuum cleaner in the prior art, and its specific structure will not be described in detail.

[0043] The multi-stage screening tank 13 has two dust discharge ports that are spaced apart vertically. The first dust suction port 31 is fixedly embedded in the upper dust discharge port and is located above the first screen 15. The second dust suction port 32 is fixedly embedded in the lower dust discharge port and is located between the first screen 15 and the second screen 18. The other end of the dust discharge pipe 33, away from the dust suction device 30, enters the multi-stage screening tank 13 and is located below the second screen 18.

[0044] The base frame 1 is equipped with a power supply box 34, and the handrail 3 is equipped with a controller 36. The controller 36 is electrically connected to the power supply box 34. In this embodiment, the controller 36 is a touch screen controller. The controller 36 is connected to the vibration motor 22, the first rotation drive device 11, the dust collection device 30, and the reduction motor of the conveying device 12.

[0045] Working principle: During use, the operator controls the electric feeding device, conveying device 12, dust collection device 30 and vibration motor 22 to start through the controller on the handrail 3.

[0046] Then, the device is moved on the ground of the grain warehouse by the handrail 3. The shovel 6 shovels up and collects the mixed grain and dust material on the ground. When the material piled on the shovel 6 moves to the left to the position of the arc-shaped guide plate 4, it is pushed to the upper left by the push plate 10 of the electric pusher device to the conveyor 12. The conveyor 12 lifts the material to the upper left into the hopper 14 of the multi-stage screening tank 13. The material is discharged downward from the bottom outlet of the hopper 14 onto the first screen 15 and flows slowly in the vibrating screening along the inclined surface of the first screen 15. Under the vibration action of the first screen 15, the grain is separated from the large particles of impurities larger than the grain size. The large particles of impurities roll onto the first ring plate 16 along the inclined surface of the first screen 15 and then flow from the discharge port on the first ring plate 16 through the first discharge pipe 17 into the storage bin 26 of the storage tank 24 for storage.

[0047] The grain, small particles, and dust sieved out by the first screen 15 fall onto the second screen 18. Under the action of vibration, the second screen 18 separates the grain from the small particles or dust smaller than the grain. The grain rolls along the inclined surface of the second screen 18 onto the second ring plate 19, and then flows from the second discharge port on the second ring plate 19 through the second discharge pipe 20 into the grain storage bin 27 of the storage tank 24 for storage.

[0048] During this process, the dust extraction device 30 extracts the dust that has escaped from the air in the multi-stage sieving tank 13 through the first dust extraction port 31 and the second dust extraction port 32, and then discharges it to the area below the second screen 18 for storage through the dust discharge pipe 33.

[0049] After running for a period of time, the first sealing door 23 can be opened to clean the dust and small particles stored at the bottom of the multi-stage screening tank 13. The second sealing door 28 can be opened to clean the large particles stored in the miscellaneous storage bin 26. The third sealing door 29 can be opened to recycle the grain stored in the grain storage bin 27.

[0050] It will be apparent to those skilled in the art that this invention is not limited to the details of the exemplary embodiments described above, and that it can be implemented in other specific forms without departing from the spirit or essential characteristics of this invention. Therefore, the embodiments should be considered illustrative and non-limiting in all respects, and the scope of this invention is defined by the appended claims and not by the foregoing description. Thus, all variations falling within the meaning and scope of equivalents of the claims are intended to be included within this invention. No reference numerals in the claims should be construed as limiting the scope of the claims.

Claims

1. A mobile dust removing and screening device for grain bins, characterized in that: It includes a horizontally set base frame (1), with rollers (2) at the bottom of the base frame (1) and a handrail (3) fixedly installed on the top left side of the base frame (1). A shovel plate component is fixedly provided on the right end of the base frame (1), and a multi-stage screening tank (13) with an upper opening is provided on the base frame (1). The base frame (1) is provided with a conveying device (12) that is inclined from left to right and from top to bottom. The conveying device (12) is located between the top of the multi-stage screening tank (13) and the left end of the shovel plate component. The conveying device (12) is used to convey the material falling from the left end of the shovel plate component to the upper opening of the multi-stage screening tank (13). The multi-stage screening tank (13) is equipped with a primary screening mechanism and a secondary screening mechanism. The primary screening mechanism is located above the secondary screening mechanism. The screen hole diameter of the primary screening mechanism is larger than that of the secondary screening mechanism. The bottom of the lowest point of the primary screening mechanism is connected to a first discharge pipe (17) that is set at an angle downwards. The bottom of the lowest point of the secondary screening mechanism is connected to a second discharge pipe (20) that is set at an angle downwards. A plurality of vertically arranged first connecting rods (21) are fixedly connected between the primary screening mechanism and the secondary screening mechanism, and a vibration motor (22) is fixedly mounted on one of the first connecting rods (21). The lower side wall of the multi-stage screening tank (13) is provided with a first sealing door (23) that can be opened and closed. The first sealing door (23) is located below the secondary screening mechanism. A storage tank (24) is provided on the base frame (1). A partition (25) is fixedly provided inside the storage tank (24). The partition (25) is used to divide the internal space of the storage tank (24) into a miscellaneous storage bin (26) and a grain storage bin (27). The miscellaneous storage bin (26) is located above the grain storage bin (27). The end of the first discharge pipe (17) away from the primary screening mechanism is inserted into the miscellaneous storage bin (26), and the end of the second discharge pipe (20) away from the secondary screening mechanism is inserted into the grain storage bin (27). The storage tank (24) has a second sealing door (28) and a third sealing door (29) that can be opened and closed on its side wall. The second sealing door (28) corresponds to the miscellaneous storage bin (26) in front and back, and the third sealing door (29) corresponds to the grain storage bin (27) in front and back. The base frame (1) is equipped with a power supply box (34), and the handrail (3) is equipped with a controller (36). The controller (36) is electrically connected to the power supply box (34), and the controller (36) is controlled by the transmission device (12).

2. A mobile dust removal and screening device for grain bins as claimed in claim 1, characterized in that: An electric material feeding device is provided on the top left side of the shovel plate component. The electric material feeding device is used to move the material at the left end of the shovel plate component to the conveying device (12).

3. A mobile dust cleaning and grain screening apparatus for use in a grain bin as defined in claim 2, wherein: The shovel plate component includes an arc-shaped guide plate (4) fixedly connected to the right end of the base frame (1). The center of the arc-shaped guide plate (4) is located at the upper right of the base frame (1). The right end of the arc-shaped guide plate (4) is fixedly connected to the left end of the horizontally set flat bottom guide plate (5). The right end of the flat bottom guide plate (5) is fixedly connected to the left end of the shovel plate (6). The right end of the shovel plate (6) is set inclined to the lower right. The arc-shaped guide plate (4) and the flat bottom guide plate (5) are both fixed with vertically arranged second baffle plates (8). The electric feeding device is set between the two second baffles (8).

4. A mobile dust cleaning and grain screening apparatus for use in a grain bin as defined in claim 3, wherein: The front and rear sides of the shovel plate (6) are fixedly provided with vertically arranged first baffle plates (7). The left end of the first baffle plate (7) is fixedly connected to the right end of the second baffle plate (8). The right end of the first baffle plate (7) is located to the left of the right end of the shovel plate (6).

5. A mobile dust cleaning and grain screening apparatus for use in a grain bin as defined in claim 3, wherein: The electric feeding device includes a rotating shaft (9) rotatably connected between two second baffle plates (8). The central axis of the rotating shaft (9) coincides with the center of the arc-shaped guide plate (4). Multiple feeding plates (10) are fixedly arranged in a circumferential interval on the circumferential side of the rotating shaft (9). The end of the feeding plate (10) away from the rotating shaft (9) can slide in contact with the right side of the arc-shaped guide plate (4). One of the second baffle plates (8) is fixedly provided with a first rotary drive device (11), the output shaft of the first rotary drive device (11) is connected to one end of the rotating shaft (9), and the controller (36) is connected to the first rotary drive device (11) for control.

6. A mobile cleaning and sorting apparatus for grain bins as described in claim 1 wherein: The multi-stage screening tank (13) is fixedly equipped with a feeding hopper (14) that is wider at the top and narrower at the bottom. The primary screening mechanism includes a first screen (15), which is a conical mesh structure that is narrow at the top and wide at the bottom. A first ring plate (16) is fixedly provided at the bottom of the first screen (15). The end of the first ring plate (16) away from the first screen (15) is fixedly connected to the inner wall of the multi-stage screening tank (13). A first discharge port that is open from top to bottom is provided on the first ring plate (16). The first discharge port is fixedly connected to the upper end of the first discharge pipe (17). The secondary screening device includes a second screen (18), which is a conical mesh structure that is narrow at the top and wide at the bottom. The screen holes of the first screen (15) are larger than those of the second screen (18). A ring-shaped second ring plate (19) is fixedly provided at the bottom of the second screen (18). The end of the second ring plate (19) away from the second screen (18) is fixedly connected to the inner wall of the multi-stage screening tank (13). A second discharge port that is open from top to bottom is provided on the second ring plate (19). The second discharge port is connected to the upper end of the second discharge pipe (20). The first connecting rod (21) is fixedly connected between the first screen (15) and the second screen (18).

7. A mobile dust removal and screening apparatus for grain bins as defined in claim 1, wherein: The base frame (1) is equipped with a dust collection device (30). The air inlet of the dust collection device (30) is connected to the first dust collection port (31) and the second dust collection port (32) by pipes. The exhaust port of the dust collection device (30) is connected to the dust discharge pipe (33). The multi-stage screening tank (13) has two dust discharge ports that are spaced apart vertically. The first dust suction port (31) is fixedly embedded in the upper dust discharge port, and the second dust suction port is fixedly embedded in the lower dust discharge port. The other end of the dust discharge pipe (33) away from the dust suction device (30) passes into the multi-stage screening tank (13) and is located below the secondary screening mechanism.

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