A multi-stage screening apparatus and method, a multi-stage sorting method

Abstract

The application discloses a multi-stage screening device and method, a multi-stage sorting method, and belongs to the technical field of screening, and aims to solve the problem of quick wear of a screening disc and a roller shaft in the prior art. The multi-stage screening device comprises a feeding groove, a grate screen and a roller shaft screen which are sequentially arranged along gangue particles, the aperture of the grate screen is smaller than that of the roller shaft screen, and the length of the grate screen is smaller than that of the roller shaft screen. The application can be used for screening and sorting of gangue particles.

Description

Technical Field

[0001] This invention belongs to the field of screening technology, and particularly relates to a multi-stage screening device and method, and a multi-stage sorting method. Background Technology

[0002] In the traditional roller screen, the material falls from one end of the roller screen into the space between the rollers. As the rollers rotate, large particles move on the roller screen, while small particles fall below the rollers through the gaps between them.

[0003] When roller screens are used for screening gangue, the screen discs and rollers wear out quickly due to the large hardness and particle size of the feed. However, due to the structure of the roller screen, it is very difficult to replace the screen discs and rollers. Summary of the Invention

[0004] In view of the above analysis, the present invention aims to provide a multi-stage screening device and method, and a multi-stage sorting system method, to solve the problem of rapid wear of the screen disc and rollers in the prior art of roller screens.

[0005] The objective of this invention is mainly achieved through the following technical solutions.

[0006] The present invention provides a multi-stage screening device, comprising a feed trough, a grate screen and a roller screen arranged sequentially along the gangue particles, wherein the aperture of the grate screen is smaller than that of the roller screen and the length of the grate screen is smaller than that of the roller screen.

[0007] Furthermore, the roller screen includes multiple parallel rollers and a screen disc disposed on the rollers.

[0008] Furthermore, the roller screen also includes a drive motor for driving the rollers to rotate.

[0009] Furthermore, the drive motor is connected to the roller via a transmission gear set.

[0010] Furthermore, the aperture of the sieve is 50–70 mm.

[0011] Furthermore, the aperture of the roller screen is 60–100 mm.

[0012] Furthermore, the length ratio of the grate screen to the roller screen is 1:2 to 2.5.

[0013] Furthermore, the angle of inclination of the sieve relative to the horizontal direction is 24–65°.

[0014] The present invention also provides a multi-stage screening method, which employs the above-mentioned multi-stage screening device and includes the following steps:

[0015] Step 1: Feed the gangue particles into the feed end of the grate screen through the feed chute;

[0016] Step 2: Under the action of gravity, the gangue particles move from the feed end of the grate screen to the discharge end of the grate screen. During the operation, the grate screen pre-screens the gangue particles.

[0017] Step 3: The pre-screened gangue particles are fed from the discharge end of the grate screen to the feed end of the roller screen. The gangue particles move from the feed end of the roller screen to the discharge end of the roller screen. During the operation, the roller screen performs a secondary screening of the pre-screened gangue particles.

[0018] The present invention also provides a multi-level sorting method, comprising the following steps:

[0019] The gangue particles are screened using the multi-stage screening method described above.

[0020] The screened gangue particles are then sorted.

[0021] Compared with the prior art, the present invention can achieve at least one of the following beneficial effects.

[0022] A) The multi-stage screening device provided by this invention combines a grate screen and a roller screen. The grate screen is installed at the discharge port of the feed chute where there are more gangue particles. On the one hand, it can pre-screen the gangue particles, screening out some of the smaller gangue particles. Then, it is screened again by the roller screen, reducing the screening load of the roller screen. This reduces the wear of the screen plate and rollers of the roller screen while ensuring processing capacity and screening efficiency. In addition, the grate screen installed between the feed chute and the roller screen can fully buffer the impact force of the gangue particles discharged from the feed chute, reducing the impact force of the gangue particles on the roller screen. This not only further reduces the wear of the screen plate and rollers of the roller screen, but also reduces the noise pollution of the multi-stage screening device.

[0023] B) The multi-stage screening device provided by the present invention uses a grate screen to pre-screen gangue particles, reducing the content of small particles, reducing the accumulation of gangue particles on the roller screen, and improving screening accuracy.

[0024] In this invention, the above-described technical solutions can be combined with each other to achieve more preferred combinations. Other features and advantages of this invention will be set forth in the following description, and some advantages may become apparent from the description or be learned by practicing the invention. The objects and other advantages of this invention can be realized and obtained through the embodiments described and the accompanying drawings, which are particularly pointed out. Attached Figure Description

[0025] The accompanying drawings are for illustrative purposes only and are not intended to limit the invention. Throughout the drawings, the same reference numerals denote the same parts.

[0026] Figure 1This is a schematic diagram of the structure of the multi-stage screening device provided in Embodiment 1 of the present invention;

[0027] Figure 2 This is a schematic diagram of the structure of the grate screen in the multi-stage screening device provided in Embodiment 1 of the present invention;

[0028] Figure 3 This is a schematic diagram of the structure of the multi-level sorting system provided in Embodiment 3 of the present invention;

[0029] Figure 4 This is a schematic diagram of the structure of the lifting component in the multi-stage sorting system provided in Embodiment 3 of the present invention.

[0030] Figure label:

[0031] 1- Conveying chute; 2- Conveying assembly; 3- Housing; 4- Compressed air tank; 5- Air compressor; 6- True color camera; 7- X-ray emitting end; 8- X-ray receiving end; 9- Main controller; 10- Waste chute; 11- Kaolin chute; 12- Support frame; 13- Lifting plate; 14- First support rod; 15- Second support rod; 16- First suction screw; 17- Second suction screw; 18- First threaded sleeve ; 19-Second threaded sleeve; 20-First rotating rod; 21-Second rotating rod; 22-First drive shaft; 23-First through hole; 24-First electromagnet; 25-Second drive shaft; 26-Second through hole; 27-Second electromagnet; 28-Slide rail; 29-Drive motor; 30-Feed trough; 31-Grate screen; 311-Narrow mesh; 312-Connecting plate; 313-Wide mesh; 314-Sliding plate; 32-Roller; 33-Screen plate. Detailed Implementation

[0032] The preferred embodiments of the present invention will now be described in detail with reference to the accompanying drawings, which constitute a part of the present invention and are used together with the embodiments of the present invention to illustrate the principles of the present invention, but are not intended to limit the scope of the present invention.

[0033] Example 1

[0034] This embodiment provides a multi-stage screening device; see [link / reference] Figure 1 It includes a feed trough 30, a grate screen 31 and a roller screen arranged sequentially along the gangue particles, wherein the aperture of the grate screen 31 is smaller than the aperture of the roller screen, and the length of the grate screen 31 is smaller than the length of the roller screen.

[0035] For example, the aperture of the grate 31 is 50-70 mm, the aperture of the roller screen is 60-100 mm, and the length ratio of the grate 31 to the roller screen is 1:2-2.5.

[0036] Compared with the prior art, the multi-stage screening device provided in this embodiment combines a grate screen 31 and a roller screen. The grate screen 31 is set at the discharge port of the feed trough 30 where there are more gangue particles. On the one hand, it can pre-screen the gangue particles, screening out some small gangue particles. Then, it is screened again by the roller screen, reducing the screening volume of the roller screen. This reduces the wear of the screen plate 33 and roller 32 of the roller screen while ensuring processing capacity and screening efficiency. In addition, the grate screen 31 is set between the feed trough 30 and the roller screen. The grate screen 31 can fully buffer the impact force of the gangue particles discharged from the feed trough 30, reducing the impact force of the gangue particles on the roller screen. This not only further reduces the wear of the screen plate 33 and roller 32 of the roller screen, but also reduces the noise pollution of the multi-stage screening device.

[0037] On the other hand, using a grate screen 31 to pre-screen the gangue particles reduces the content of small particles, which can reduce the accumulation of gangue particles on the roller screen and improve screening accuracy.

[0038] In order to ensure the smooth operation of the gangue particles on the grate 31, the grate 31 is, for example, tilted at an angle of 24 to 65° relative to the horizontal direction.

[0039] To facilitate adjustment of the length of the grate 31, the structure of the grate 31 adopts a modular design. For details, see [link to relevant documentation]. Figure 2 It includes at least one set of narrow screens and at least one set of wide screens arranged alternately, with the narrow and wide screens detachably and fixedly connected. Thus, in practical applications, by connecting different numbers of narrow and wide screens, the overall length of the grate 31 can be adjusted, thereby regulating the screening efficiency and screening effect of the grate 31 to adapt to the pre-screening of gangue particles with different compositions.

[0040] From the perspective of screening efficiency and screening effect, the number of narrow and wide screens mentioned above is 2 to 4 sets.

[0041] The narrow screen includes a narrow mesh 311 and two connecting plates 312. One side of the narrow mesh 311 is fixedly connected to one of the connecting plates 312, and the other side of the narrow mesh 311 is fixedly connected to the other connecting plate 312. The wide screen includes a wide mesh 313 and two sliding plates 314. One side of the wide mesh 313 is fixedly connected to one of the sliding plates 314, and the other side of the wide mesh 313 is fixedly connected to the other sliding plate 314. A groove is formed on the inner side of the sliding plate 314.

[0042] In adjacent narrow and wide screens, the connecting plate 312 and the sliding plate 314 are slidably and fixedly connected, with the connecting plate 312 located inside the sliding plate 314.

[0043] It is worth noting that, due to the gap at the connection between the narrow and wide screens, gangue particles can easily fall directly through the gaps in the grate 31 without being screened. Therefore, the length of the sliding plate 314 of the wide screen is greater than the length of the wide mesh 313, and the length of the connecting plate 312 of the narrow screen is less than the length of the narrow mesh 311. Along the plane in which the gangue particles travel, the narrow mesh 311 and the wide mesh 313 are not in the same plane and have overlapping portions. Thus, by improving the specific parameters and structure of the narrow and wide screens, the gap at the connection between the narrow and wide screens can be eliminated, thereby further improving the screening accuracy.

[0044] It should be noted that the mesh sizes of the narrow mesh 311 and the wide mesh 313 are the same, and the mesh sizes of the overlapping parts of the narrow mesh 311 and the wide mesh 313 are completely overlapping to avoid changes in the screening size.

[0045] Specifically, the structure of the roller screen includes multiple parallel rollers 32, a screen disc 33 mounted on the rollers 32, and a drive motor 29 for driving the rollers 32 to rotate. The drive motor 29 is connected to the rollers 32 through a transmission gear set, and the rotation direction of the rollers 32 is the same as the running direction of the gangue particles.

[0046] Example 2

[0047] This embodiment provides a multi-stage screening method, using the multi-stage screening device provided in Embodiment 1, including the following steps:

[0048] Step 1: Feed the gangue particles into the feed end of the grate screen through the feed chute;

[0049] Step 2: Under the action of gravity, the gangue particles move from the feed end of the grate screen to the discharge end of the grate screen. During the operation, the grate screen pre-screens the gangue particles.

[0050] Step 3: The pre-screened gangue particles are fed from the discharge end of the grate screen to the feed end of the roller screen. The gangue particles move from the feed end of the roller screen to the discharge end of the roller screen. During the operation, the roller screen performs a secondary screening of the pre-screened gangue particles.

[0051] Compared with the prior art, the beneficial effects of the multi-stage screening method provided in this embodiment are basically the same as those of the multi-stage screening device provided in Embodiment 1, and will not be described in detail here.

[0052] Example 3

[0053] This embodiment provides a multi-level sorting method, including the following steps:

[0054] Step 1: Feed the coal gangue particles into the feed end of the grate screen through the feed chute;

[0055] Step 2: The grate screen pre-screens the coal gangue particles, and the roller screen performs a secondary screening of the pre-screened coal gangue particles.

[0056] Step 3: Coal gangue particles run on the conveying assembly, and a true-color camera acquires real-time images of the coal gangue particle surface and sends them to the main controller;

[0057] Step 4: The main controller identifies the surface image and obtains the RGB values ​​of the surface image, and determines whether the RGB values ​​are within the RGB threshold range (e.g., 80-110).

[0058] If not, then the coal gangue particles are determined to be non-kaolin particles, i.e., waste particles, which fall into the waste chute.

[0059] If so, and it is preliminarily determined that the coal gangue particles are kaolin particles, then proceed to step 5;

[0060] Step 5: The main controller calculates the transport time of the kaolin particles to the X-ray detector based on the distance between the true color camera and the X-ray detector and the operating speed of the transport component, and starts a countdown based on the transport time. When the countdown ends, the main controller sends an X-ray detection command to the X-ray detector.

[0061] Step 6: The X-ray detector receives the X-ray detection command and acquires an internal image of the coal gangue particles;

[0062] Step 7: The main controller identifies the internal image and obtains the penetration value, and determines whether the penetration value is within the penetration threshold range (e.g., 200-600);

[0063] If not, then the coal gangue particles are determined to be non-kaolin particles, i.e., waste particles, which fall into the waste chute.

[0064] If so, confirm that the coal gangue particles are kaolin particles, and proceed to step 8;

[0065] Step 8: The main controller calculates the discharge time of kaolin particles to the discharge end of the conveying component based on the distance between the X-ray detector and the discharge end of the conveying component and the running speed of the conveying component, and starts a countdown based on the discharge time. When the countdown ends, the main controller sends a blowing command to the blowing component.

[0066] Step 9: The blowing assembly receives the blowing command and blows the kaolin particles conveyed to the discharge end of the conveying assembly, giving the kaolin particles an upward initial velocity so that they can fall into the kaolin chute.

[0067] Compared with the prior art, the beneficial effects of the multi-stage sorting method provided in this embodiment are basically the same as those of the multi-stage screening method provided in Embodiment 1, and will not be described in detail here.

[0068] For example, the above multi-level sorting method employs a multi-level sorting system with the following structure, see [link to documentation]. Figure 3 Understandably, in order to achieve further sorting, the aforementioned multi-stage sorting system includes a multi-stage screening device, a conveying assembly 2, a jetting assembly, a true-color camera 6, an X-ray detector, a waste chute 10, a kaolin chute 11, and a main controller 9. The discharge end of the multi-stage screening device is connected to the feed end of the conveying assembly 2. The true-color camera 6 and the X-ray detector are sequentially arranged along the waste rock particle transport path of the conveying assembly 2. The jetting assembly is located below the discharge end of the conveying assembly 2. The waste chute 10 and the kaolin chute 11 are located below the discharge end of the conveying assembly 2 and are arranged sequentially away from the discharge end. The main controller 9 is connected to the true-color camera 6, the X-ray detector, and the jetting assembly.

[0069] The multi-stage sorting system described above utilizes physical methods, combining two highly efficient and accurate methods: X-ray identification and true-color camera 6 identification. First, the true-color camera 6 is used to perform preliminary identification of the gangue particles, initially sorting out the preliminarily determined kaolin particles. Then, an X-ray detector is used for secondary confirmation. This not only effectively improves the sorting quality, accuracy, and efficiency of kaolin, but also effectively reduces the waste and environmental pollution of kaolin, thereby achieving the comprehensive utilization of gangue particles through resource recovery and waste reduction.

[0070] Specifically, the structure of the X-ray detector includes an X-ray emitting end 7 and an X-ray receiving end 8 corresponding to the position of the X-ray emitting end 7. The X-ray emitting end 7 is located above the gangue particles, and the X-ray receiving end 8 is located below the gangue particles. Exemplarily, the X-ray emitting end 7 and the X-ray receiving end 8 are arranged in a vertical direction.

[0071] In order to effectively reduce the amount of dust in the sorting process, the above-mentioned multi-stage sorting system also includes a housing 3, a conveying component 2, a blowing end of a blowing component, a true color camera 6 and an X-ray detector, all of which are located inside the housing 3. The housing 3 has an inlet and an outlet at its two ends, respectively. The conveying component 2 is arranged along the direction from the inlet to the outlet, with the inlet end of the conveying component 2 close to the inlet and the outlet end of the conveying component 2 close to the outlet. The X-ray emitting end 7 and the true color camera 6 are located on the top of the housing 3.

[0072] Specifically, the structure of the conveying component 2 includes a frame, a conveyor belt, rollers, a drive motor, and a conveying controller. The rollers are located at both ends of the frame and are rotatably connected to the frame. The two ends of the conveyor belt are respectively fitted onto the rollers. The rotation of the rollers drives the conveyor belt to run. The drive motor is used to drive the rollers to rotate. The conveying controller is connected to the main controller 9 and the drive motor respectively, and is used to control the opening and closing of the drive motor and the rotation speed.

[0073] Specifically, the structure of the spray assembly includes an air compressor 5, a compressed air tank 4, a nozzle, and a spray controller. The air compressor 5, the compressed air tank 4, and the nozzle are connected in sequence. The spray controller is connected to the main controller 9 and is used to control the opening and closing of the nozzle.

[0074] To better separate kaolin particles from waste particles and ensure that the kaolin particles fall into the kaolin chute 11, the aforementioned conveying assembly 2 also includes a lifting component, see [link to assembly 2]. Figure 4 The lifting component is located in front of the roller near the discharge end, with a distance of 0.1 to 0.5 mm between it and the roller. It is used to lift the conveyor belt corresponding to the kaolin particles, thereby increasing the falling height and horizontal movement distance of the kaolin particles, and thus ensuring that the kaolin particles fall into the kaolin chute 11.

[0075] Specifically, the structure of the lifting component includes a support frame 12, a telescopic component, and a lifting plate 13. The support frame 12 is fixedly connected to the machine frame, the telescopic component is located in the support frame 12, and the lower end of the telescopic component is fixedly connected to the support frame 12. The lifting plate 13 is located at the top of the telescopic component, and the telescopic component supports the lifting plate 13. When the conveyor belt corresponding to the kaolin particles runs above the telescopic component, the top of the telescopic component moves upward, lifting the conveyor belt corresponding to the kaolin particles, thereby increasing the height of the kaolin particles.

[0076] For example, the support frame 12 has drive shafts on both sides and a slide rail 28 at the bottom; the drive shafts are connected to the rollers via a synchronous belt, and the rollers drive the drive shafts to rotate synchronously via the synchronous belt; a through hole is opened in the center of the drive shaft, and an electromagnet is installed in the through hole; the telescopic component includes a support rod, an adsorption screw, a threaded sleeve, and a rotating rod, which is inclined from top to side away from the support frame 12; the bottom end of the support rod is inserted into the slide rail 28 and slidably connected to the slide rail 28; the top end of the support rod is fixedly connected to the outer wall of the threaded sleeve; the threaded sleeve is sleeved on the outer wall of the adsorption screw and threadedly connected to the adsorption screw; the bottom end of the rotating rod is rotatably connected to the outer wall of the threaded sleeve; and the top end of the rotating rod is rotatably connected to the lifting plate 13.

[0077] During implementation, if the gangue particles are initially determined to be kaolin particles, when the countdown ends, the controller energizes the electromagnet, which generates an attractive force. This force attracts the suction screw, causing it to move closer to the through hole. The angle between the rotating rod and the horizontal direction increases, driving the lifting plate 13 to rise. The suction screw is inserted into the through hole, and the support rod slides along the slide rail 28. The transmission shaft drives the suction screw to rotate, further driving the threaded sleeve to slide along the suction. The angle between the rotating rod and the horizontal direction further increases, driving the lifting plate 13 to rise further. The rise of the lifting plate 13 lifts the conveyor belt corresponding to the kaolin particles, increasing the height of the kaolin particles.

[0078] It is worth noting that, in order to achieve automatic reset of the adsorption screw and prevent the conveyor belt corresponding to the waste particles from being lifted, for example, the number of the above-mentioned telescopic components is two sets. That is, the lifting component includes a first support rod 14, a second support rod 15, a first adsorption screw 16, a second adsorption screw 17, a first threaded sleeve 18, a second threaded sleeve 19, a first rotating rod 20, and a second rotating rod 21. A first drive shaft 22 is provided on one side of the support frame 12. The first drive shaft 22 is connected to the first roller through a first synchronous belt. The first roller drives the first drive shaft 22 to rotate synchronously through the first synchronous belt. A first through hole 23 is opened in the center of the first drive shaft 22, and a first electromagnet 24 is provided in the first through hole 23. A second drive shaft 25 is provided on the other side of the support frame 12. The second drive shaft 25 is connected to the second roller through a second synchronous belt. The second roller drives the second drive shaft 25 to rotate synchronously through the second synchronous belt. A second through hole 26 is opened in the center of the second drive shaft 25, and a second electromagnet 27 is provided in the second through hole 26.

[0079] From top to bottom, both the first rotating rod 20 and the second rotating rod 21 are inclined towards the side away from the support frame 12; the bottom ends of the first support rod 14 and the second support rod 15 are inserted into the slide rail 28 and slidably connected to the slide rail 28; the top end of the first support rod 14 is fixedly connected to the outer wall of the first threaded sleeve 18; the first threaded sleeve 18 is sleeved on the outer wall of the first suction screw 16 and threadedly connected to the first suction screw 16; the bottom end of the first rotating rod 20 is rotatably connected to the outer wall of the first threaded sleeve 18; the top end of the first rotating rod 20 is rotatably connected to the lifting plate 13; the second support rod 15 and the second support rod 15... The bottom end is inserted into the slide rail 28 and slidably connected to the slide rail 28. The top end of the second support rod 15 is fixedly connected to the outer wall of the second threaded sleeve 19. The second threaded sleeve 19 is sleeved on the outer wall of the second adsorption screw 17 and threadedly connected to the second adsorption screw 17. The bottom end of the second rotating rod 21 is rotatably connected to the outer wall of the second threaded sleeve 19, and the top end of the second rotating rod 21 is rotatably connected to the lifting plate 13. The lifting component also includes a return spring. One end of the return spring is rotatably connected to the first adsorption screw 16, and the other end of the return spring is rotatably connected to the second adsorption screw 17. The return spring is always in a stretched state.

[0080] During implementation, if the gangue particles are initially determined to be kaolin particles, when the countdown ends, the controller energizes the first electromagnet 24 and the second electromagnet 27. The first electromagnet 24 generates an attractive force to attract the first suction screw 16, and the second electromagnet 27 generates an attractive force to attract the second suction screw 17. This causes the first suction screw 16 to move closer to the first through hole 23, and the second suction screw 17 to move closer to the second through hole 26. The first suction screw 16 is inserted into the first through hole 23, and the second suction screw 17 is inserted into the second through hole 26. The first support rod 14 and the second support rod 15 both slide along the slide rail 28. The angle between the first rotating rod 20 and the second rotating rod 21 and the horizontal direction increases. The first rotating rod 20 and the second rotating rod 21 jointly drive the lifting plate 13 to rise. The rise of the lifting plate 13 causes the conveyor belt corresponding to the kaolin particles to be lifted, increasing the height of the kaolin particles.

[0081] The above description is only a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any changes or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in the present invention should be included within the scope of protection of the present invention.

Claims

1. A multi-stage sorting system, characterized in that, The system includes a feed trough, a grate screen, a roller screen, and a conveying assembly arranged sequentially along the gangue particles. The grate screen has a smaller aperture than the roller screen, and its length is also shorter than the roller screen's length. The grate screen comprises at least one set of narrow screens and at least one set of wide screens arranged alternately, with the narrow and wide screens detachably and fixedly connected. Each narrow screen includes a narrow mesh and two connecting plates, with one side of the narrow mesh fixedly connected to one of the connecting plates and the other side fixedly connected to the other connecting plate. Each wide screen includes a wide mesh and two sliding plates, with one side of the wide mesh fixedly connected to one of the sliding plates. The moving plate is fixedly connected, and the other side of the wide screen is fixedly connected to another sliding plate. A sliding groove is opened on the inner side of the sliding plate. In adjacent narrow and wide screens, the connecting plate and the sliding plate are slidably fixedly connected, and the connecting plate is located inside the sliding plate. The length of the sliding plate of the wide screen is greater than the length of the wide screen, and the length of the connecting plate of the narrow screen is less than the length of the narrow screen. Along the plane direction of the gangue particles, the narrow screen and the wide screen are not in the same plane and have overlapping parts. The mesh size of the narrow screen and the wide screen are the same, and the mesh of the overlapping part of the narrow screen and the wide screen completely overlaps. The conveying assembly includes a conveyor belt, rollers, and a lifting component. Both ends of the conveyor belt are fitted onto the rollers. The lifting component is located in front of the rollers near the discharge end. The lifting component includes a support frame, a telescopic component, and a lifting plate. The support frame is fixedly connected to the machine frame. The telescopic component is located within the support frame, with its lower end fixedly connected to the support frame. The lifting plate is located at the top of the telescopic component, supporting it. When the conveyor belt corresponding to the kaolin particles moves above the telescopic component, the top of the telescopic component moves upward, lifting the conveyor belt corresponding to the kaolin particles, thus increasing the height of the kaolin particles. Transmission mechanisms are located on both sides of the support frame. The shaft has a slide rail at the bottom of the support frame; the drive shaft is connected to the roller via a synchronous belt, and the roller drives the drive shaft to rotate synchronously via the synchronous belt; a through hole is opened in the center of the drive shaft, and an electromagnet is installed in the through hole; the telescopic component includes a support rod, an adsorption screw, a threaded sleeve, and a rotating rod. From top to bottom, the rotating rod is inclined to the side away from the support frame. The bottom end of the support rod is inserted into the slide rail and slidably connected to the slide rail. The top end of the support rod is fixedly connected to the outer wall of the threaded sleeve. The threaded sleeve is fitted onto the outer wall of the adsorption screw and threadedly connected to the adsorption screw. The bottom end of the rotating rod is rotatably connected to the outer wall of the threaded sleeve, and the top end of the rotating rod is rotatably connected to the lifting plate.

2. The multi-stage sorting system according to claim 1, characterized in that, The roller screen includes multiple parallel rollers and a screen disc mounted on the rollers.

3. The multi-stage sorting system according to claim 2, characterized in that, The roller screen also includes a drive motor for driving the rollers to rotate.

4. The multi-stage sorting system according to claim 3, characterized in that, The drive motor is connected to the roller via a transmission gear set.

5. The multi-stage sorting system according to claim 1, characterized in that, The aperture of the sieve is 50~70mm.

6. The multi-stage sorting system according to claim 1, characterized in that, The aperture of the roller screen is 60~100mm.

7. The multi-stage sorting system according to claim 1, characterized in that, The length ratio of the grate screen to the roller screen is 1:2~2.

5.

8. The multi-stage sorting system according to claim 1, characterized in that, The angle of inclination of the sieve relative to the horizontal direction is 24~65°.

9. A multi-stage screening method, characterized in that, The multi-stage sorting system as described in any one of claims 1 to 8, wherein the multi-stage screening method comprises the following steps: Step 1: Feed the gangue particles into the feed end of the grate screen through the feed chute; Step 2: Under the action of gravity, the gangue particles move from the feed end of the grate screen to the discharge end of the grate screen. During the operation, the grate screen pre-screens the gangue particles. Step 3: The pre-screened gangue particles are fed from the discharge end of the grate screen to the feed end of the roller screen. The gangue particles move from the feed end of the roller screen to the discharge end of the roller screen. During the operation, the roller screen performs a secondary screening of the pre-screened gangue particles.

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