Multi-stage screening equipment and method for silica sand processing

Abstract

The invention discloses multi-stage screening equipment and method for silica sand processing, and relates to the technical field of silica sand screening, the multi-stage screening equipment comprises a horizontally arranged shell, a rotatable outer screen drum is arranged in the shell in a sleeved mode, a rotatable inner screen drum is arranged in the outer screen drum in a sleeved mode, the mesh number of the inner screen drum is larger than that of the outer screen drum, and the mesh number of the inner screen drum is larger than that of the outer screen drum. A large particle discharging channel is arranged between the outer screen drum and the shell, and the inner screen drum, the outer screen drum and the shell are all in a circular truncated cone shape. The outer screen drum is adopted for feeding, the screening area of the outer screen drum is far larger than that of the inner screen drum, and when the same silica sand is treated, the unit load of the outer screen drum is far smaller than that of the inner screen drum; the defects that in a traditional silica sand screening process, when materials are fed into an inner screen drum for screening, the unit load remarkably exceeds the limit, and due to the fact that the material layer of the inner screen drum is too thick, the screen penetrating impedance is multiplied, and the screen hole clogging probability gradient is increased are overcome.

Description

Technical Field

[0001] The present invention relates to the technical field of silica sand screening, and specifically to a multi-stage screening device and method for silica sand processing. Background Art

[0002] Multi-stage screening is the core technological link for silica sand to achieve particle size gradient classification. Through precise classification of silica sand particle size, it ensures the coordinated optimization among the improvement of the physical and chemical properties of silica sand materials, the intensive utilization of resources, and the matching degree with downstream application scenarios.

[0003] When traditional sands are subjected to particle size gradient classification, the screening device uses a structure of nested multi-layer sieve drums for multi-stage screening. For example, Figure 1 as shown in the three-stage screening device, this device consists of an outer sieve drum with a larger mesh number sleeved over an inner sieve drum with a smaller mesh number; during operation, the silica sand placed in the inner sieve drum is classified through rotational motion. Based on the difference in the particle diameters of silica sand particles (A > B > C), three-stage products are formed after screening: the largest-diameter A particles remain in the inner sieve drum and are separately collected; the medium-diameter B particles are retained in the outer sieve drum for dedicated recycling; the smallest C particles are discharged through the sieve holes of the outer sieve drum and are independently captured. This classification device realizes the three-stage precise separation of silica sand materials through the structural design of multi-layer sleeves.

[0004] However, in the above silica sand screening process, due to the constraints of the inner sieve drum structure (small diameter and low load-bearing strength), there are two core technological defects when the silica sand to be processed directly falls into the inner sieve drum: First, due to the difference in the area of the cylinder body, the unit load of the inner sieve drum is significantly exceeded, exacerbating the structural fatigue of the sieve body and the attenuation of the service life; Second, due to the characteristics of the low diameter ratio and mechanical strength limitations, the thickness of the material layer in the inner sieve drum surges, leading to the deterioration of the dynamic screening efficiency, specifically manifested as the coupled failure phenomenon of doubling the screening impedance and the gradient increase in the probability of sieve hole blockage. Summary of the Invention

[0005] The purpose of the present invention is to provide a multi-stage screening device and method for silica sand processing to solve the problems raised in the above background art.

[0006] To achieve the above purpose, the present invention provides the following technical solution: A multi-stage screening device for silica sand processing, including a horizontally arranged housing, a rotatable outer sieve drum sleeved inside the housing, a rotatable inner sieve drum sleeved inside the outer sieve drum, the mesh number of the inner sieve drum being greater than that of the outer sieve drum, a large-particle discharge channel being provided between the outer sieve drum and the housing, and the inner sieve drum, the outer sieve drum, and the housing all being frustum-shaped; further including: A receiving plate, which is installed between the inner sieve drum and the outer sieve drum, is used to prevent the silica sand screened by the outer sieve drum from falling into the inner cavity of the outer sieve drum and to receive and guide the silica sand screened by the inner sieve drum; fine-particle discharge channels and medium-particle discharge channels are respectively provided between the receiving plate and the inner sieve drum and the outer sieve drum; A plurality of baffles are circumferentially and equidistantly distributed along the outer sieve cylinder, and the radial extensions of the baffles can intersect at the axis of the outer sieve cylinder; a chamber is formed jointly between two adjacent baffles, the outer sieve cylinder and the housing. A feeding port is used for filling silica sand into the chamber. A pushing component is installed on the outer sieve cylinder and is used for pushing the accumulated silica sand away from the baffle.

[0007] As a further technical solution of the present invention: the baffle is a V-shaped plate with an obtuse angle, and the opening of its bent part faces away from the rotation direction of the outer sieve cylinder.

[0008] As a further technical solution of the present invention: the pushing component includes a pushing plate, the pushing plate is hermetically inlaid in the baffle, and a power component is arranged on the large-diameter end of the outer sieve cylinder, and the power component is used to separate the pushing plate from the baffle.

[0009] As a further technical solution of the present invention: the power component includes a first telescopic member, the first telescopic member is located at the large-diameter end of the outer sieve cylinder and rotates synchronously with the outer sieve cylinder, one end of the first telescopic member is hinged with a guiding plate, the guiding plate is slidably connected to the sieve surface of the outer sieve cylinder along the circumferential direction of the outer sieve cylinder, and the guiding plate and the pushing plate are assembled to form a hopper.

[0010] As a further technical solution of the present invention: an auxiliary pushing component is further included, the auxiliary pushing component includes a connecting plate, one end of the connecting plate is rotatably connected with a connecting member, the other end of the connecting plate is inserted into the pushing plate, the end of the pushing plate far away from the connecting plate is rotatably connected with the guiding plate, the connecting member is slidably connected with a movable piece fixedly connected with the guiding plate, and a second telescopic member is fixedly installed on the movable piece, and the movable end of the second telescopic member is fixedly connected with the connecting member.

[0011] As a further technical solution of the present invention: a supporting component is further included, the supporting component includes a ring body fixedly connected with the outer sieve cylinder, a bottom frame and a bracket, the ring body is rotatably connected to the large-diameter end of the housing, and the other end of the first telescopic member is hinged to the ring body; the bottom frame is located below the housing, and the bracket is arranged on one side of the bottom frame and is fixedly connected with the receiving plate.

[0012] As a further technical solution of the present invention: the bracket is slidably connected with the bottom frame.

[0013] As a further technical solution of the present invention: a blanking component is arranged on the bottom frame, the blanking component includes a first blanking ring fixedly connected with the bottom frame, a first blanking channel is opened on the first blanking ring, a second blanking ring is fixedly connected to the outside of the first blanking ring, and a second blanking channel is opened on the second blanking ring.

[0014] Compared with the prior art, the beneficial effects of the present invention are: The present invention adopts the feeding method of an outer sieve cylinder. The screening area of the outer sieve cylinder is much larger than that of the inner sieve cylinder. When processing the same amount of silica sand, the unit load of the outer sieve cylinder is much smaller than that of the inner sieve cylinder, overcoming the defects in the traditional silica sand screening process, such as the significant over-limit of the unit load during the screening of the inner sieve cylinder feeding, the doubling of the screening impedance caused by the too thick material layer in the inner sieve cylinder, and the increase in the probability gradient of sieve hole blockage. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 It is a schematic diagram of the states of the inner sieve cylinder and the outer sieve cylinder of a three-stage screening device, where the small figure (a) is a schematic diagram of the state when feeding to the inner sieve cylinder, and the small figure (b) is a schematic diagram of the state after screening is completed; Figure 2 It is a schematic diagram of the overall structure of the present invention; Figure 3 For Figure 2 The enlarged view at position A in Figure 4 It is a schematic diagram of the connection structure among the inner sieve cylinder, the outer sieve cylinder and the housing of the present invention; Figure 5 It is a schematic diagram of the positional relationship among the chamber, the housing and the outer sieve cylinder of the present invention; Figure 6 It is a schematic diagram of the positional relationship among the material receiving plate, the outer sieve cylinder and the ring body of the present invention; Figure 7 It is a schematic diagram of the inner sieve cylinder, the outer sieve cylinder, the housing, the large particle discharge channel, the medium particle discharge channel and the fine particle discharge channel of the present invention; Figure 8 It is a side view of the large particle discharge channel, the medium particle discharge channel, the fine particle discharge channel and the return material area of the present invention; Figure 9 It is a schematic diagram of the positional relationship among the baffle plate, the receiving groove and the first telescopic member of the present invention; Figure 10 It is a schematic diagram of the positional relationship among the push plate, the first telescopic member, the second telescopic member and the baffle plate of the present invention; Figure 11 It is a schematic diagram of the positional relationship among the guide plate, the push plate, the push plate, the connecting plate and the connecting member of the present invention; Figure 12 It is a schematic diagram of the movable piece, the second telescopic member and the separated state of the baffle plate and the push plate of the present invention; Figure 13 It is a schematic diagram of the connection relationship between the second telescopic member and the movable piece of the present invention; Figure 14 It is a schematic diagram of the guide plate of the present invention; Figure 15 It is a schematic diagram of the initial material accumulation layer and the long accumulation layer of the present invention; Figure 16 It is a schematic diagram when the first telescopic member pushes the guide plate to move of the present invention; Figure 17 Schematic diagram of the relative movement of the pushing plate and the guiding plate of the present invention relative to the baffle during material pushing; Figure 18 Schematic diagram of the positional relationship among the housing, the first blanking ring and the first blanking channel of the present invention; Figure 19 Schematic diagram of the positional relationship among the housing, the second blanking ring and the second blanking channel of the present invention; Figure 20 Schematic diagram of the first blanking ring and the second blanking ring of the present invention under cross-section; Figure 21 Schematic diagram of the connection relationship among the material receiving plate, the inner sieve cylinder and the bracket of the present invention; Figure 22 Schematic diagram of the positional relationship among the ring body, the outer sieve cylinder, the guiding plate and the first telescopic member of the present invention.

[0016] In the drawings: 1, inner sieve cylinder; 2, outer sieve cylinder; 3, housing; 4, material receiving plate; 5, baffle; 6, chamber; 7, feeding port; 8, displacement sensor; 9, pushing plate; 10, first telescopic member; 11, guiding plate; 12, connecting plate; 13, connecting member; 14, second telescopic member; 15, movable piece; 16, ring body; 17, chassis; 18, bracket; 19, first blanking ring; 20, first blanking channel; 21, second blanking ring; 22, second blanking channel; 23, return material area; 24, large particle discharge channel; 25, medium particle discharge channel; 26, fine particle discharge channel; 27, annular groove; 28, motor; 29, roller; A1, initial silicon sand accumulation layer; A2, long accumulation layer. Detailed Description of the Invention

[0017] The embodiments of the present invention will be described in detail below. The examples of the embodiments are shown in the drawings, in which the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout.

[0018] The embodiments described below with reference to the drawings are exemplary and are intended to explain the present invention, and should not be construed as limiting the present invention.

[0019] Please refer to Figures 1 - 22, the present invention provides a technical solution: a multi-stage screening device for silica sand processing, used for screening silica sand of different particle sizes, including a horizontally arranged housing 3, a rotatable outer sieve cylinder 2 sleeved inside the housing 3, and a rotatable inner sieve cylinder 1 sleeved inside the outer sieve cylinder 2. The inner sieve cylinder 1, the outer sieve cylinder 2, and the housing 3 are all frustum-shaped and coaxially installed. The mesh number of the inner sieve cylinder 1 is greater than that of the outer sieve cylinder 2. A large-particle discharge channel 24 is provided between the outer sieve cylinder 2 and the housing 3; it also includes a receiving plate 4, a plurality of baffles 5, a feeding port 7 for filling silica sand in the chamber 6, and a pushing component; wherein the number of the baffles 5 can be determined according to the actual screening requirements. The baffle 5 is designed as a V-shaped plate with an obtuse angle, and the opening of the bent part faces away from the rotation direction of the outer sieve cylinder 2.

[0020] The receiving plate 4 is installed between the inner sieve cylinder 1 and the outer sieve cylinder 2, used to prevent the silica sand screened by the outer sieve cylinder 2 from falling into the inner cavity of the outer sieve cylinder 2 and to receive and discharge the silica sand screened by the inner sieve cylinder 1. A fine-particle discharge channel 26 and a medium-particle discharge channel 25 are respectively provided between the receiving plate 4 and the inner sieve cylinder 1 and the outer sieve cylinder 2.

[0021] A plurality of baffles 5 are evenly distributed along the circumferential direction of the outer sieve cylinder 2, and the radial extensions of each baffle 5 can intersect at the axis of the outer sieve cylinder 2; a chamber 6 is jointly formed between adjacent two baffles 5 and the outer sieve cylinder 2 and the housing 3.

[0022] The pushing component is installed on the outer sieve cylinder 2, and is used to push the accumulated silica sand away from the baffle 5.

[0023] As Figure 2 , Figures 4 - 9 shown: during the rotation and screening process of the inner sieve cylinder 1 and the outer sieve cylinder 2, the silica sand is sequentially added into the interiors of each chamber 6 through the feeding port 7; the screening process of the silica sand in each chamber 6 is the same. Select one chamber 6 as an example, and the screening process of the silica sand in this chamber 6 will be described in detail; The feeding port 7 is opened at the large-diameter end of the housing 3, and the position of the feeding port 7 is in the area between c and a1. Among them, the feeding port 7 is optimally set at the a point. During feeding, the silica sand is evenly transported into the interior of the chamber 6 through the feeding port 7 by a vibrating feeder (the vibrating feeder is not shown in the figure, and its use and installation are conventional settings and will not be elaborated). At this time, the baffle 5 is in an inclined state (the height of the end of the baffle 5 close to the large-diameter end of the housing 3 is lower than the other end), and the silica sand accumulates on the side of the baffle 5 close to the large-diameter end of the housing 3. After feeding, the chamber 6 and the outer sieve cylinder 2 rotate clockwise around the axis of the outer sieve cylinder 2 at the same time. When the chamber 6 rotates past the a point, the pusher assembly is activated to quickly push the accumulated silica sand away from the baffle 5. The silica sand pushed away from the baffle 5 makes a spiral progressive movement along the arc-shaped sieve surface of the outer sieve cylinder 2, so that the silica sand is in full contact with the sieve surface of the outer sieve cylinder 2. Under the combined action of the gravity component and the rotation of the sieve body, the silica sand generates axial tumbling to achieve the first-stage screening of particle size; the setting of the pusher assembly can prevent the silica sand on the baffle 5 from moving in the groove formed by the baffle 5 and the outer sieve cylinder 2, ensuring the screening effect during the movement of the chamber 6 from the a point to the a1 point. When the chamber 6 moves from the a1 point to the a2 point, the silica sand remaining on the outer sieve cylinder 2 makes a parabolic movement along the tangential direction of the sieve surface under the vector superposition of the Coriolis acceleration and the gravitational acceleration. The movement of the silica sand forms a dynamic screening with the sieve holes, thus completing the first-stage screening process of the silica sand in a single chamber 6. It should be noted that the pusher assembly can be intelligently controlled and automatically reset before the chamber 6 rotates to the feeding port 7 position again; The silica sand that does not pass through the sieve holes of the outer sieve cylinder 2 is discharged out of the equipment through the large-particle discharge channel 24. The silica sand that passes through the sieve holes of the outer sieve cylinder 2 falls into the area from point a to point a2 of the inner sieve cylinder 1 under the guiding action of the receiving plate 4 and completes the second-stage screening of the silica sand through the rotating inner sieve cylinder 1; During the second-stage screening process, the silica sand that does not pass through the sieve holes of the inner sieve cylinder 1 is discharged out of the equipment through the medium-particle discharge channel 25. The silica sand that passes through the sieve holes of the inner sieve cylinder 1 falls into the fine-particle discharge channel 26 and is discharged out of the equipment through the fine-particle discharge channel 26.

[0024] Through the first-stage screening and the second-stage screening, the multi-stage screening of the silica sand can be completed. In the case of processing the same amount of silica sand, this equipment abandons the traditional feeding method of the inner sieve cylinder 1 and adopts the feeding of the outer sieve cylinder 2. The screening area of the outer sieve cylinder 2 is much larger than that of the inner sieve cylinder 1. When processing the same silica sand, the unit load of the outer sieve cylinder 2 is much smaller than that of the inner sieve cylinder 1, overcoming the defects of the significantly over-limit unit load during the feeding and screening of the inner sieve cylinder 1 in the traditional silica sand screening process, as well as the doubling of the screening resistance and the gradient increase of the probability of sieve hole blockage caused by the too-thick material layer of the inner sieve cylinder 1.

[0025] In addition, two circulating conveyors should be installed at appropriate positions during specific implementation. The circulating conveyor can be an LSY cement screw conveyor, but is not limited to the LSY cement screw conveyor. The specific structure of the circulating conveyor is prior art, and the installation of the circulating conveyor is conventional technology in this field. Therefore, the structure and installation of the circulating conveyor will not be elaborated and are not shown in the figure. One of the circulating conveyors is used to input the silica sand discharged from the large-grain discharge channel 24 back into the large-grain discharge channel 24 from the highest point of the large-grain discharge channel 24; the other circulating conveyor is used to input the silica sand discharged from the medium-grain discharge channel 25 back into the medium-grain discharge channel 25 from the highest point of the medium-grain discharge channel 25 (the highest point positions of the large-grain discharge channel 24 and the medium-grain discharge channel 25 are Figure 8 the indicated material return area 23), so that the silica sand can be screened multiple times, ensuring the screening effect of the silica sand.

[0026] Refer to Figure 7 、 Figure 11 、 Figure 12 and Figure 15 , the pusher assembly includes a push plate 9 and a power assembly. The push plate 9 is hermetically embedded in the baffle 5, and the power assembly is arranged on the large-diameter end of the outer sieve cylinder 2. The power assembly pushes the push plate 9 away from the baffle 5; After the silica sand to be screened enters the chamber 6, under the guidance of the baffle 5, the silica sand to be screened flows and accumulates on the push plate 9. During the process of the outer sieve cylinder 2 rotating from the a point position to the a1 point position, the potential energy of the silica sand carried on the push plate 9 gradually increases, and the tendency of the silica sand to move from the large-diameter end to the small-diameter end of the outer sieve cylinder 2 becomes greater, resulting in the evolution of the initial accumulation layer (A1) of the silica sand on the push plate 9 into a long accumulation layer (A2) with an increased length but a decreased height. Part of the silica sand on the push plate 9 is discharged outside the device through the groove formed by the baffle 5 and the outer sieve cylinder 2, affecting the screening effect. The pusher assembly is provided. At the initial stage when the a point position rotates to the a1 point position, the silica sand accumulated on the push plate 9 is directly and quickly pushed to the high point position of the chamber 6. Under the guidance of the push plate 9, the pushed-out silica sand makes a spiral progressive movement along the arc-shaped sieve surface of the outer sieve cylinder 2. The silica sand generates axial tumbling under the combined action of the gravity component and the rotation of the sieve body, and fully contacts the sieve surface of the outer sieve cylinder 2.

[0027] Among them, the power assembly includes a first telescopic member 10. The first telescopic member 10 is located at the large-diameter end of the outer sieve cylinder 2 and rotates synchronously with the outer sieve cylinder 2. One end of the first telescopic member 10 is hinged with a guide plate 11. The guide plate 11 is slidably connected to the sieve surface of the outer sieve cylinder 2 along the circumferential direction of the outer sieve cylinder 2. The guide plate 11 and the push plate 9 are assembled to form an integral hopper, so that the push plate 9 and the first telescopic member 10 are indirectly hinged. When the push plate 9 needs to be separated from the baffle 5, the first telescopic member 10 extends, and the guide plate 11 slides along the circumferential direction of the outer sieve cylinder 2 on the sieve surface of the outer sieve cylinder 2, driving the push plate 9 to make the same movement and separate from the baffle 5.

[0028] Further, an auxiliary material pushing component is also provided to push out the silica sand remaining in the hopper, preventing the silica sand from staying in the hopper and being unable to be screened. The auxiliary material pushing component includes a connecting plate 12. One end of the connecting plate 12 is rotatably connected to a connecting piece 13, and the other end of the connecting plate 12 is inserted into a push plate 9. The end of the push plate 9 away from the connecting plate 12 is rotatably connected to a guide plate 11. A movable piece 15 fixedly connected to the guide plate 11 is slidably connected to the connecting piece 13. A second telescopic member 14 is fixedly installed on the movable piece 15, and the movable end of the second telescopic member 14 is fixedly connected to the connecting piece 13.

[0029] Refer to 10- Figure 17 , while the power component is performing an action, the auxiliary material pushing component also acts. During the action, the second telescopic member 14 shortens and drives the connecting piece 13 to move. The movement of the connecting piece 13 drives the connecting plate 12 to move synchronously. The connecting plate 12 rotates under the limiting action of the push plate 9, and at the same time, the push plate 9 also rotates synchronously. Finally, the push plate 9, the connecting plate 12, and the guide plate 11 are in a coplanar state, and the hopper formed by the assembly of the guide plate 11 and the push plate 9 disappears, that is, the problem of residual silica sand in the hopper is solved, making the screening of silica sand more thorough; the first telescopic member 10 and the second telescopic member 14 can be one of the cylinders, electric cylinders, and electric telescopic rods that can be controlled by wireless signals in the prior art. The specific structure will not be elaborated. Both the first telescopic member 10 and the second telescopic member 14 can be controlled to act based on the displacement sensor 8 to realize the extension and shortening of the first telescopic member 10 and the second telescopic member 14. The position where the displacement sensor 8 emits a signal can be installed according to actual production requirements, which is a conventional setting and will not be elaborated.

[0030] A support component is also provided. The support component includes a ring body 16 fixedly connected to the outer sieve cylinder 2, a chassis 17, and a bracket 18. The ring body 16 is rotatably connected to the large-diameter end of the housing 3, and the other end of the first telescopic member 10 is hinged to the ring body 16; the chassis 17 is located below the housing 3, and the bracket 18 is slidably connected to one side of the chassis 17 and fixedly connected to the receiving plate 4.

[0031] Refer to Figure 2 , Figure 3 and Figure 22 , the bracket 18 slides relative to the chassis 17, and the bracket 18 can be moved out from the inside of the chassis 17, facilitating the maintenance and installation of the inner sieve cylinder 1 and the receiving plate 4; The ring body 16 can be driven by a driving component. The driving component can be a combination of a gear ring and a motor 28. A gear ring is fixedly installed on the outer circle of the ring body 16, and the gear ring meshes with a gear fixedly connected to the output shaft of the motor 28. The motor 28 is fixedly connected to the housing 3. A roller 29 is rotatably provided on the housing 3, and an annular groove 27 matching the roller 29 is provided on the ring body 16. When the ring body 16 rotates, the roller 29 rolls along the annular groove 27 to prevent the outer sieve cylinder 2 from detaching; in specific implementation, the outer sieve cylinder 2 and the inner sieve cylinder 1 also need to be assembled with the above structure to prevent detachment.

[0032] A blanking component is provided on the chassis 17. The blanking component includes a first blanking ring 19 fixedly connected to the chassis 17. A first blanking channel 20 is formed in the first blanking ring 19. A second blanking ring 21 is fixedly connected to the outside of the first blanking ring 19. A second blanking channel 22 is formed in the second blanking ring 21.

[0033] Refer to Figures 18 - 21 , the large-grain discharge channel 24 is communicated with the first blanking channel 20 of the first blanking ring 19, and the medium-grain discharge channel 25 is communicated with the second blanking channel 22 of the second blanking ring 21, so as to realize the separate recovery of silica sand and the transfer during subsequent cyclic screening.

Claims

1. A multi - stage screening device for silica sand processing, including a horizontally arranged housing, an outer sieve cylinder that can rotate is sleeved inside the housing, and an inner sieve cylinder that can rotate is sleeved inside the outer sieve cylinder. It is characterized in that, The mesh number of the inner sieve cylinder is greater than that of the outer sieve cylinder. A large-particle discharge channel is provided between the outer sieve cylinder and the housing. The inner sieve cylinder, the outer sieve cylinder, and the housing are all frustum-shaped. Further included are: A material receiving plate, which is installed between the inner sieve cylinder and the outer sieve cylinder, used to prevent the silica sand screened by the outer sieve cylinder from falling into the inner cavity of the outer sieve cylinder and to receive and export the silica sand screened by the inner sieve cylinder. Fine-particle discharge channels and medium-particle discharge channels are respectively provided between the material receiving plate and the inner sieve cylinder and the outer sieve cylinder; Multiple baffles, which are equidistantly distributed along the circumferential direction of the outer sieve cylinder and the radial extensions of each baffle can intersect at the axis of the outer sieve cylinder; Chambers are jointly formed between two adjacent baffles and the outer sieve cylinder and the housing; A feeding port, used for filling the silica sand in the chamber; A material pushing assembly, which is installed on the outer sieve cylinder and used to push the accumulated silica sand away from the baffle.

2. The multi - stage screening device for silica sand processing according to claim 1, characterized in that: The baffle is a V-shaped plate with an obtuse angle, and the opening of its bent part faces away from the rotation direction of the outer sieve cylinder.

3. The multi - stage screening device for silica sand processing according to claim 1, characterized in that: The material pushing assembly includes a push plate, which is hermetically inlaid in the baffle. A power assembly is arranged on the large-diameter end of the outer sieve cylinder, and the power assembly is used to separate the push plate from the baffle.

4. The multi - stage screening device for silica sand processing according to claim 3, characterized in that: The power assembly includes a first telescopic member. The first telescopic member is located at the large-diameter end of the outer sieve cylinder and rotates synchronously with the outer sieve cylinder. One end of the first telescopic member is hinged with a guide plate. The guide plate is slidably connected to the sieve surface of the outer sieve cylinder along the circumferential direction of the outer sieve cylinder. The guide plate and the push plate are assembled to form a hopper.

5. The multi - stage screening device for silica sand processing according to claim 4, characterized in that: An auxiliary material pushing assembly is further included. The auxiliary material pushing assembly includes a connecting plate. One end of the connecting plate is rotatably connected with a connecting member. The other end of the connecting plate is inserted into the push plate. The end of the push plate away from the connecting plate is rotatably connected with the guide plate. The connecting member is slidably connected with a movable piece fixedly connected with the guide plate. A second telescopic member is fixedly installed on the movable piece, and the movable end of the second telescopic member is fixedly connected with the connecting member.

6. The multi - stage screening device for silica sand processing according to claim 5, characterized in that: A support assembly is further included. The support assembly includes a ring body fixedly connected with the outer sieve cylinder, a chassis, and a bracket. The ring body is rotatably connected to the large-diameter end of the housing. The other end of the first telescopic member is hinged to the ring body; The chassis is located below the housing, and the bracket is arranged on one side of the chassis and fixedly connected with the material receiving plate.

7. The multi - stage screening device for silica sand processing according to claim 6, characterized in that: The bracket is slidably connected with the chassis.

8. The multi - stage screening device for silica sand processing according to claim 7, characterized in that: A blanking assembly is arranged on the chassis. The blanking assembly includes a first blanking ring fixedly connected with the chassis. A first blanking channel is opened on the first blanking ring. A second blanking ring is fixedly connected to the outside of the first blanking ring. A second blanking channel is opened on the second blanking ring.

9. A screening method using the multi - stage screening device for silica sand processing according to any one of claims 1 - 8, characterized in that, The method includes the following steps: S1: Pre-crushing and impurity removal of silicon raw ore: Coarsely crush the silicon raw ore through a jaw crusher, then remove iron through a metal detector. The iron-removed coarsely crushed silicon raw ore enters a cone crusher for secondary crushing, and the particle size of the material is controlled below 10 mm; S2: Multi-stage screening: Evenly input the product obtained in S1 into each chamber through the feeding port, and complete the three-stage screening of the product obtained in S1 by rotating the inner sieve cylinder and the outer sieve cylinder; S3: Magnetic separation strengthening: Respectively input the material obtained in S2 into an oil-cooled vertical ring high-gradient magnetic separator with a magnetic separation intensity of 15,000 Gauss for four to five times of iron removal, and the iron impurity content of the material obtained in S2 can be reduced to below 20 ppm.

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