A method for separating native polysilicon from carbon-silicon and an apparatus using the same

Abstract

The application discloses a primary polycrystalline silicon carbon silicon separation method, which can divide carbon head material fragments into two categories according to the carbon content, respectively uses corresponding separation liquid for treatment, and sets different treatment time, so that higher separation efficiency is achieved. Meanwhile, a device used by the primary polycrystalline silicon carbon silicon separation method is disclosed. The classification equipment comprises a classification box, the classification box is a water tank, a lifting type bottom support is arranged at the bottom of the classification box, a fixed pipe is fixedly installed on the bottom support, a discharge hole is arranged on the bottom support for the fixed pipe, the discharge hole is blocked by a sealing plug, a movable pipe is installed in the classification box through a horizontal moving support, and a feeding structure with a screening function is arranged at the top of the classification box. The classification can be carried out according to the carbon content, and subsequent separation treatment work of the fragments according to the carbon content can be ensured.

Description

Technical Field

[0001] This invention relates to the field of inorganic material processing technology, specifically to a method and apparatus for separating primary polycrystalline silicon carbon. Background Technology

[0002] Currently, the main industrial method for producing polysilicon is the Siemens process. This process requires using graphite chucks to connect seed crystals, allowing the primary polysilicon to grow on the seed crystal. Inevitably, after production, a certain amount of polysilicon adheres to the graphite and cannot be separated. This polysilicon material grown near the graphite chuck or with graphite adhering to its surface is called "carbon head material." With the rising price of polysilicon, separating and utilizing this portion of polysilicon from the graphite would greatly help reduce the production cost of polysilicon.

[0003] Currently, commonly used methods for separating carbon and silicon include manual removal, mechanical separation, acid immersion, and heat treatment, among which acid immersion is a relatively efficient method. Chinese patent CN201010195803.9 discloses a method for removing carbon from polycrystalline silicon carbon head material. This method mainly involves crushing the carbon head material and separating it into three categories: the first category consists of carbon-free silicon blocks; the second category consists of silicon blocks with a carbon layer no thicker than 1 cm on the surface; and the third category consists of silicon blocks with a carbon layer or a carbon layer on the surface exceeding 1 cm. Starting from the sorting of the carbon head material, different methods are used for different materials, which can improve efficiency and reduce costs. However, the above method, which involves separating the carbon head material into three categories, does not propose a practical classification method or corresponding processing equipment, making it difficult to achieve the desired classification effect. Simply relying on manual separation is extremely inefficient. Summary of the Invention

[0004] The purpose of this invention is to provide a method and apparatus for separating carbon from virgin polycrystalline silicon, so as to classify and separate carbon materials according to their carbon content, thereby solving the problems mentioned in the background art.

[0005] To achieve the above objectives, the present invention provides the following technical solution: a method for separating primary polycrystalline silicon from silicon carbide, the separation method comprising the following steps:

[0006] Step S1: Crush the carbon material into uniformly sized fragments and sieve them. Re-crush any excessively large fragments to ensure material uniformity.

[0007] Step S2: The crushed material is divided into two categories according to its carbon content using a sorting device: one category has a low carbon content and the other has a high carbon content.

[0008] Step S3: Perform material classification and processing. Place the two materials in different carbon-silicon separation solutions for cleaning, followed by water washing, purging, acid washing, water washing again, and drying. For materials with low carbon content, the carbon-silicon separation solution used is a mixed solution of concentrated sulfuric acid, concentrated nitric acid, and potassium permanganate, with a weight ratio of 20 parts concentrated sulfuric acid, 1-10 parts concentrated nitric acid, and 0.1-0.5 parts potassium permanganate, and a cleaning time of 2-8 hours. For materials with high carbon content, the carbon-silicon separation solution used is a mixed solution of concentrated sulfuric acid and potassium permanganate, with a weight ratio of 20 parts concentrated sulfuric acid and 0.1-0.3 parts potassium permanganate, and a cleaning time of 8-24 hours.

[0009] An apparatus for separating primary polycrystalline silicon carbon silicon is disclosed. The sorting equipment includes a sorting box, which is a water tank. The bottom of the sorting box is equipped with a lifting base, and a fixed pipe is fixedly installed on the base. The base has a discharge hole for the fixed pipe, which is blocked by a sealing plug. A movable pipe is installed in the sorting box via a horizontally moving bracket. Both the fixed pipe and the movable pipe have through holes. The horizontally moving bracket controls the docking and misalignment of the movable pipe with the fixed pipe. The top of the sorting box is equipped with a feeding structure with a screening function. Carbon head fragments are fed into the movable pipe through the feeding structure. By moving and misaligning the movable pipe, the fragments with a fast falling speed enter the fixed pipe, and the fragments with a slow falling speed fall into the base.

[0010] Preferably, the sorting box is supported by a support foot, and the sorting box is equipped with a water inlet pipe and a water outlet pipe. The sorting box is filled with water. A first cylinder is provided on the support foot, and a base is installed on the first cylinder. A sealing ring is provided on the base.

[0011] Preferably, the fixing tubes are arranged and installed on the top of the base, and the connection between the fixing tubes and the base is provided with a discharge hole, and the sealing plug is provided with a pull ring.

[0012] Preferably, the sorting box is provided with a partition plate, and a horizontal moving bracket is installed on the partition plate. The functional part and the driving part of the horizontal moving bracket are respectively installed in the water-filled space and the waterless space on both sides of the partition plate. The number and arrangement of the movable pipes are the same as those of the fixed pipes.

[0013] Preferably, the feeding structure includes a feeding hopper fixedly installed on the top of the sorting box, and a transition hopper is provided on the feeding hopper. A main screen is provided on the feeding hopper, and the main screen is prevented from being placed on the channel of the feeding hopper by a hanging edge.

[0014] Preferably, the feeding structure further includes a feeding pipe fixedly installed on the transition hopper and a movable push plate slidably installed on the transition hopper. The movable push plate is provided with a ramp and a connecting rod is fixedly installed on the movable push plate. The connecting rod extends into the protective sleeve. The protective sleeve is provided with a balance spring and a wedge is provided at the end of the connecting rod. An electric push rod is provided in the protective sleeve and connected to the wedge.

[0015] Preferably, a suspension rope is fixedly connected to the movable push plate, and the suspension rope is connected to the upper screen. The upper screen is movably installed in the feed pipe, and a return spring is fixedly connected to the upper screen. The return spring is fixedly connected to the fixed block, and a lower screen is fixedly installed in the feed pipe.

[0016] Preferably, the number of feed pipes is the same as the number of movable pipes, and the feed pipes are located above the movable pipes. The upper screen and the lower screen are both located inside the cavity of the feed pipes, and the screen holes of the upper screen and the lower screen are staggered. The upper screen is located above the lower screen. The fixing block is fixedly installed on the inner wall of the feed pipe, and the hanging rope is connected to the center of the upper screen.

[0017] Compared with the prior art, the beneficial effects of the present invention are:

[0018] 1. This invention provides a method for classifying and separating virgin polycrystalline silicon, which can separate carbon head fragments into two categories according to their carbon content, process them separately using corresponding separation liquids, and set different processing times to achieve a more efficient separation effect;

[0019] 2. This invention provides a corresponding sorting device for carbon head material fragments, which can classify them according to the amount of carbon content. It mainly uses the characteristics of higher carbon content, lower relative density of fragments, and slower falling speed in water to complete the sorting work, which can ensure that the fragments can be further separated according to their carbon content.

[0020] 3. In order to ensure the effectiveness of buoyancy-based sorting in this invention, a feeding structure is provided on the sorting equipment. The top of the feeding structure is a feeding hopper, which contains a main screen. The main screen prevents large pieces of material from entering the feeding hopper. Pieces that meet the size requirements can fall into a transition hopper. The transition hopper is equipped with a movable push plate, which can push the pieces of material to prevent accumulation. While the movable push plate moves left and right, it can intermittently cause the two screens to open the channel, ensuring that the pieces of material enter the moving tube in a flat state at the same time, thus ensuring the sorting effect. Attached Figure Description

[0021] Figure 1 This is a first schematic diagram of the structure of the present invention;

[0022] Figure 2 This is a second schematic diagram of the structure of the present invention;

[0023] Figure 3 This is a schematic diagram of the internal structure of the box in this invention;

[0024] Figure 4 This is a schematic diagram of the pipeline structure of the present invention;

[0025] Figure 5 This is a schematic diagram of the active tube structure of the present invention;

[0026] Figure 6 This is a schematic diagram of the fixed tube structure of the present invention;

[0027] Figure 7 This is a schematic diagram of the base structure of the present invention;

[0028] Figure 8 This is a schematic diagram of the feed hopper structure of the present invention;

[0029] Figure 9 This is a schematic diagram of the transition bucket structure of the present invention;

[0030] Figure 10 This is a schematic diagram of the material control structure of the present invention.

[0031] In the diagram: 1. Sorting box; 2. Inlet pipe; 3. Outlet pipe; 4. Support leg; 5. First cylinder; 6. Base support; 7. Sealing ring; 8. Fixing pipe; 9. Discharge hole; 10. Sealing plug; 11. Divider plate; 12. Limiting sleeve; 13. Movable frame; 14. Mounting plate; 15. Movable pipe; 16. Limiting rod; 17. Limiting spring; 18. Second cylinder; 19. Feed hopper; 20. Transition hopper; 21. Main screen; 22. Hanging edge; 23. Feeding pipe; 24. Movable push plate; 25. Ramp; 26. Connecting rod; 27. Protective sleeve; 28. Balance spring; 29. ​​Wedge block; 30. Electric push rod; 31. Lifting rope; 32. Upper screen; 33. Reset spring; 34. Fixing block; 35. Lower screen. Detailed Implementation

[0032] The present invention will now be further described with reference to the accompanying drawings and specific embodiments. It should be noted that, without conflict, the various embodiments or technical features described below can be arbitrarily combined to form new embodiments. It should be understood that the described embodiments are merely some embodiments of the present invention, and not all embodiments. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are within the scope of protection of the present invention.

[0033] Please see Figures 1 to 10 This invention provides a technical solution: a method for separating primary polycrystalline silicon and silicon carbide, the separation method comprising the following steps:

[0034] Step S1: Crush the carbon material into uniformly sized fragments and sieve them. Re-crush any excessively large fragments to ensure material uniformity.

[0035] Step S2: The crushed material is divided into two categories according to its carbon content using a sorting device: one category has a low carbon content and the other has a high carbon content.

[0036] Step S3: Perform material classification and processing. Place the two materials in different carbon-silicon separation solutions for cleaning, followed by water washing, purging, acid washing, water washing again, and drying. For materials with low carbon content, the carbon-silicon separation solution used is a mixed solution of concentrated sulfuric acid, concentrated nitric acid, and potassium permanganate, with a weight ratio of 20 parts concentrated sulfuric acid, 1-10 parts concentrated nitric acid, and 0.1-0.5 parts potassium permanganate, and a cleaning time of 2-8 hours. For materials with high carbon content, the carbon-silicon separation solution used is a mixed solution of concentrated sulfuric acid and potassium permanganate, with a weight ratio of 20 parts concentrated sulfuric acid and 0.1-0.3 parts potassium permanganate, and a cleaning time of 8-24 hours.

[0037] This invention provides a method for classifying and separating virgin polycrystalline silicon, which can separate carbon head fragments into two categories according to their carbon content, process them separately using corresponding separation liquids, and set different processing times to achieve a more efficient separation effect.

[0038] An apparatus for separating primary polycrystalline silicon carbon silicon includes a sorting box 1, which is a water tank. A lifting base 6 is provided at the bottom of the sorting box 1, and a fixed pipe 8 is fixedly installed on the base 6. A discharge hole 9 is provided on the base 6 for the fixed pipe 8, and the discharge hole 9 is blocked by a sealing plug 10. A movable pipe 15 is installed in the sorting box 1 via a horizontally movable support. Both the fixed pipe 8 and the movable pipe 15 have through holes. The horizontally movable support controls the docking and misalignment of the movable pipe 15 with the fixed pipe 8. A feeding structure with screening function is provided at the top of the sorting box 1. Carbon head fragments are fed into the movable pipe 15 through the feeding structure. By moving and misaligning the movable pipe 15, the fragments with a fast falling speed enter the fixed pipe 8, while the fragments with a slow falling speed fall into the base 6.

[0039] This invention provides a classification device for carbon head material fragments, which can classify them according to their carbon content. The classification is mainly based on the characteristics that the higher the carbon content, the lower the relative density of the fragments, and the slower the falling speed in water. This ensures that the fragments can be further separated according to their carbon content.

[0040] The sorting box 1 is supported by the support foot 4, and the sorting box 1 is equipped with a water inlet pipe 2 and a water outlet pipe 3. The sorting box 1 is filled with water. The support foot 4 is equipped with a first cylinder 5, and the base 6 is installed on the first cylinder 5. The base 6 is equipped with a sealing ring 7.

[0041] The sorting process of this invention is carried out in the sorting box 1. Water is injected into the sorting box 1 through the water inlet pipe 2, and water is drained through the water outlet pipe 3. The bottom support 6 of the sorting box 1 adopts a detachable structure, and the bottom support 6 can be removed from the sorting box 1 by the first cylinder 5, so as to recycle the sorted materials.

[0042] The fixing tubes 8 are arranged and installed on the top of the base 6, and the connection between the fixing tubes 8 and the base 6 is provided with a discharge hole 9. The sealing plug 10 is provided with a pull ring.

[0043] The fixed tubes 8 arranged in the sorting box 1 are mainly used for collecting low carbon content scraps. After collection, the scraps can be taken out from the discharge hole 9 by opening the sealing plug 10. The high carbon content scraps will fall on the bottom tray 6 and can be collected directly after the bottom tray 6 falls.

[0044] The sorting box 1 is equipped with a partition plate 11, and a horizontal moving bracket is installed on the partition plate 11. The functional part and the driving part of the horizontal moving bracket are respectively installed in the water space and the waterless space on both sides of the partition plate 11. The number and arrangement of the movable pipes 15 are the same as those of the fixed pipes 8.

[0045] The horizontal moving support can be a support with a reciprocating drive component, for example, such as... Figure 5 As shown, the movable frame 13 is installed through the upper limit sleeve 12 of the partition plate 11. The movable frame 13 is provided with an installation plate 14, which can be used to install the movable tube 15. The movable frame 13 is slidably installed on the limit rod 16 on the side of the partition plate 11, and the limit rod 16 is provided with a limit spring 17. The movable frame 13 is driven by the second cylinder 18 on the partition plate 11.

[0046] When the scrap falls into the movable tube 15 through the feeding structure, the buoyancy of the scrap with high and low carbon content in the water is different. Therefore, the falling speed can be distinguished according to the carbon content. The scrap with low carbon content and high silicon content will enter the fixed tube 8 first from the movable tube 15. The intermediate value of the carbon content can be controlled by the timing of the horizontal moving bracket. When the horizontal moving bracket drives the movable tube 15 to move, the movable tube 15 and the fixed tube 8 are misaligned. Subsequently, the scrap with high carbon content will fall from the movable tube 15 onto the bottom support 6, thus completing the sorting work.

[0047] The feeding structure includes a feeding hopper 19 fixedly installed on the top of the sorting box 1, and a transition hopper 20 is provided on the feeding hopper 19. A main screen 21 is provided on the feeding hopper 19, and the main screen 21 is prevented from being placed on the channel of the feeding hopper 19 by a hanging edge 22.

[0048] To ensure the effectiveness of sorting by buoyancy, the present invention also includes a feeding structure, which ensures that the size of the fragments is uniform and that they fall into the movable tube 15 as simultaneously as possible.

[0049] The uppermost part of the feeding structure is the feeding hopper 19, which is equipped with a main screen 21. The main screen 21 prevents large pieces of material from entering the feeding hopper 19, while pieces of material that meet the size requirements can fall into the transition hopper 20.

[0050] The feeding structure also includes a feeding pipe 23 fixedly installed on the transition hopper 20, and a movable push plate 24 slidably installed on the transition hopper 20. The movable push plate 24 is provided with a ramp 25, and a connecting rod 26 is fixedly installed on the movable push plate 24. The connecting rod 26 extends into the protective sleeve 27. A balance spring 28 is provided in the protective sleeve 27, and a wedge block 29 is provided at the end of the connecting rod 26. An electric push rod 30 is provided in the protective sleeve 27 and connected to the wedge block 29.

[0051] The transition hopper 20 is equipped with a movable push plate 24. By extending and retracting the electric push rod 30 isolated in the protective sleeve 27, the wedge block 29 can be driven to drive the connecting rod 26 to move back and forth, thereby causing the movable push plate 24 to move back and forth. The ramp 25 on it pushes the crushed material to prevent accumulation and allows the crushed material to enter the feed pipe 23.

[0052] A hanging rope 31 is fixedly connected to the movable push plate 24, and the hanging rope 31 is connected to the upper screen 32. The upper screen 32 is movably installed in the feed pipe 23, and a return spring 33 is fixedly connected to the upper screen 32. The return spring 33 is fixedly connected to the fixed block 34, and a lower screen 35 is fixedly installed in the feed pipe 23.

[0053] Because the screen holes of the upper screen 32 and the lower screen 35 are misaligned, when the two are stacked together, they can block the broken material. While the movable push plate 24 moves left and right, it can pull the hanging rope 31, so that the upper screen 32 can move against the elastic force of the return spring 33.

[0054] The number of feed pipes 23 is the same as that of movable pipes 15, and the feed pipes 23 are located above the movable pipes 15. The upper screen 32 and the lower screen 35 are both located inside the cavity of the feed pipe 23, and the screen holes of the upper screen 32 and the lower screen 35 are staggered. The upper screen 32 is located above the lower screen 35. The fixing block 34 is fixedly installed on the inner wall of the feed pipe 23, and the hanging rope 31 is connected to the center of the upper screen 32.

[0055] When the upper screen 32 moves upward, a space appears between it and the lower screen 35. The broken material can fall onto the lower screen 35 first, and then enter the feed pipe 23. This feeding method can ensure that the broken material enters the movable pipe 15 in a flat state as much as possible, thus ensuring the sorting effect.

[0056] Furthermore, this feeding method allows the fragmented material to enter the feed pipe 23 in batches for differentiation, and to be carried out at certain time intervals. This ensures that after the previous batch of material is separated according to its carbon content, the next batch of fragmented material is fed into the movable pipe 15 in a flat state. This prevents the situation where the lower density material that enters the movable pipe earlier falls slowly and cannot be distinguished from the higher density material that enters the movable pipe later.

[0057] When using the sorting equipment: First, the sorting work of this invention is carried out in the sorting box 1. Water is injected into the sorting box 1 through the water inlet pipe 2, and water is drained through the water outlet pipe 3. The bottom support 6 of the sorting box 1 adopts a detachable structure. The bottom support 6 can be removed from the sorting box 1 by the first cylinder 5, and then the sorted materials can be recycled. The fixed pipes 8 arranged in the sorting box 1 are mainly used for collecting fragments with low carbon content. After collection, the fragments can be taken out from the discharge hole 9 by opening the sealing plug 10. The fragments with high carbon content will fall onto the bottom support 6 and can be collected directly after the bottom support 6 falls. The horizontal moving support can be a support with a reciprocating drive component, for example, such as Figure 5As shown, the movable frame 13 is installed via the upper limit sleeve 12 of the partition plate 11. The movable frame 13 is equipped with an mounting plate 14 for installing the movable tube 15. The movable frame 13 is slidably mounted on the limiting rod 16 on the side of the partition plate 11, and the limiting rod 16 is equipped with a limiting spring 17. The movable frame 13 is driven by the second cylinder 18 on the partition plate 11. When the crushed material falls into the movable tube 15 through the feeding structure, the buoyancy of the crushed material with high and low carbon content in water is different, thus allowing for separation based on carbon content. The falling speed is such that fragments with low carbon content and high silicon content will first enter the fixed tube 8 from the movable tube 15. The timing of the horizontal moving support can control the intermediate value of the carbon content difference. When the horizontal moving support moves the movable tube 15, the movable tube 15 and the fixed tube 8 are misaligned, and the fragments with higher carbon content will subsequently fall from the movable tube 15 onto the bottom support 6, thus completing the sorting process. To ensure the effectiveness of sorting using buoyancy, the invention also includes a feeding structure, which ensures that the fragments are of uniform size and fall into the movable tube as simultaneously as possible. In section 15, the uppermost part of the feeding structure is the feeding hopper 19, which is equipped with a main screen 21. The main screen 21 prevents large pieces of material from entering the feeding hopper 19. Pieces that meet the size requirements can fall into the transition hopper 20. The transition hopper 20 is equipped with a movable push plate 24. By extending and retracting the electric actuator 30 isolated in the protective sleeve 27, the wedge block 29 can be driven to move the connecting rod 26 back and forth, thereby causing the movable push plate 24 to move back and forth. The ramp 25 on it pushes the pieces of material to prevent accumulation, allowing the pieces of material to enter the feeding pipe. In section 23, due to the misalignment of the screen holes, the upper screen 32 and the lower screen 35 can block the broken material when they are stacked together. While the movable push plate 24 moves left and right, it can pull the hanging rope 31, so that the upper screen 32 can move against the elastic force of the return spring 33. When the upper screen 32 moves upward, a space appears between it and the lower screen 35, and the broken material can fall onto the lower screen 35 first, and then enter the feed pipe 23. By adopting this feeding method, it can be ensured that the broken material enters the movable pipe 15 in a flat state as much as possible, ensuring the sorting effect.

[0058] The above embodiments are merely preferred embodiments of the present invention and should not be construed as limiting the scope of protection of the present invention. Any modifications made by those skilled in the art based on the above concepts without creative effort shall fall within the scope of protection of the present invention.

Claims

1. An apparatus used in a method for separating primary polycrystalline silicon from silicon carbide, characterized in that: The system includes a sorting box (1), which is a water tank. The bottom of the sorting box (1) is provided with a lifting base (6), and a fixed pipe (8) is fixedly installed on the base (6). The base (6) is provided with a discharge hole (9) for the fixed pipe (8), and the discharge hole (9) is blocked by a sealing plug (10). The sorting box (1) is provided with a movable pipe (15) installed by a horizontal moving bracket. Both the fixed pipe (8) and the movable pipe (15) are provided with through holes. The movable pipe (15) is connected and misaligned with the fixed pipe (8) by the horizontal moving bracket. The top of the sorting box (1) is provided with a feeding structure with screening function. Carbon head material fragments are fed into the movable pipe (15) through the feeding structure. By moving and misaligning the movable pipe (15), the fragments with a fast falling speed enter the fixed pipe (8) and the fragments with a slow falling speed fall into the base (6). The sorting box (1) is supported by a support foot (4), and the sorting box (1) is provided with a water inlet pipe (2) and a water outlet pipe (3). The sorting box (1) is filled with water. The support foot (4) is provided with a first cylinder (5), and the base (6) is installed on the first cylinder (5). The base (6) is provided with a sealing ring (7). The fixing tubes (8) are arranged and installed on the top of the base (6), and the connection between the fixing tubes (8) and the base (6) is provided with a discharge hole (9). The sealing plug (10) is provided with a pull ring. The sorting box (1) is provided with a partition plate (11), and a horizontal moving bracket is installed on the partition plate (11). The functional part and the driving part of the horizontal moving bracket are respectively installed in the water space and the waterless space on both sides of the partition plate (11). The number and arrangement of the movable pipes (15) are the same as those of the fixed pipes (8). The feeding structure includes a feeding hopper (19) fixedly installed on the top of the sorting box (1), and a transition hopper (20) is provided on the feeding hopper (19). A main screen (21) is provided on the feeding hopper (19), and the main screen (21) is prevented from being in the channel of the feeding hopper (19) by a hanging edge (22). The feeding structure also includes a feeding pipe (23) fixedly installed on the transition hopper (20) and a movable push plate (24) slidably installed on the transition hopper (20). The movable push plate (24) is provided with a ramp (25) and a connecting rod (26) is fixedly installed on the movable push plate (24). The connecting rod (26) extends into the protective sleeve (27). The protective sleeve (27) is provided with a balance spring (28) and a wedge (29) is provided at the end of the connecting rod (26). An electric push rod (30) is provided in the protective sleeve (27) and connected to the wedge (29).

2. The apparatus used in the method for separating primary polycrystalline silicon and silicon carbide according to claim 1, characterized in that: A suspension rope (31) is fixedly connected to the movable push plate (24), and the suspension rope (31) is connected to the upper screen (32). The upper screen (32) is movably installed in the feed pipe (23), and a return spring (33) is fixedly connected to the upper screen (32). The return spring (33) is fixedly connected to the fixed block (34), and a lower screen (35) is fixedly installed in the feed pipe (23).

3. The apparatus used in the method for separating primary polycrystalline silicon from silicon carbide according to claim 2, characterized in that: The number of feed pipes (23) is the same as that of movable pipes (15), and the feed pipes (23) are located above the movable pipes (15). The upper screen (32) and the lower screen (35) are both located inside the cavity of the feed pipe (23), and the screen holes of the upper screen (32) and the lower screen (35) are staggered. The upper screen (32) is located above the lower screen (35). The fixing block (34) is fixedly installed on the inner wall of the feed pipe (23), and the hanging rope (31) is connected to the center of the upper screen (32).

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