Screening device and dry granulation equipment

Abstract

This application discloses a screening device and its dry granulation equipment. It includes a housing, a lifting support, a material curtain forming structure, a blowing component, and a negative pressure dust removal mechanism. In operation, material enters the housing through the feed inlet and is dispersed into a uniform material curtain by the material curtain forming structure, fully exposing particles and dust. The blowing component blows air towards the recovery port, while the negative pressure dust removal mechanism simultaneously draws in air, forming a transverse airflow that passes through the material curtain, blowing dust to the recovery port and sucking it into the recovery component for separation and recovery. Clean particles continue to fall and are discharged through the outlet to enter the next process. This device effectively removes dust from the particle surface, improves product quality, and ensures stable operation of continuous production.

Description

Technical Field

[0001] This application relates to the field of dry granulation technology, and in particular to a screening device and its dry granulation equipment. Background Technology

[0002] Dry granulation is a process that uses mechanical pressure to directly agglomerate powder into granules without the use of liquid binders.

[0003] Traditional electrolyte salts (such as difluorosulfonylimide salts, difluorooxalate borate, difluorodioxalate phosphate, tetrafluoroborate, and difluorophosphate) are basically chemically crystallized, dried, and directly packaged. This process easily leads to material agglomeration and dust accumulation, causing difficulties in feeding during downstream electrolyte preparation. The high viscosity of the material also contributes to static electricity, and significant raw material residue remains in the packaging. Furthermore, the electrolyte tends to accumulate at the bottom of the electrolyte solvent, resulting in prolonged dissolution times. Dry granulation processes, on the other hand, produce electrolytes with uniform particle size, good sphericity, high particle strength, and convenient packaging. Feeding during electrolyte preparation is also easier, with reduced heat release during dissolution and dust, significantly improving convenience.

[0004] Currently, typical dry granulation equipment mainly consists of a screw feeder, a tableting assembly (containing at least one pair of pressure rollers), a crushing and granulating assembly, and a vibrating screen. The workflow is as follows: powdered material is forcibly conveyed by the screw to the gap between the pressure rollers, where it is compressed into continuous, dense flakes under high pressure; the flakes then enter the crushing and granulating assembly, where they are crushed and shaped into particles of the target size by high-speed rotating blades; finally, the finished particles are obtained by vibrating screening, while unqualified fine powder is returned to the feed end through a closed loop to be mixed with fresh material and pressed again to achieve continuous production. However, in practical applications, it has been observed that some particles still have a lot of dust adhering to their surface after vibrating screening, which not only affects the final quality of the particles but also adversely affects subsequent continuous production. Utility Model Content

[0005] This application aims to address at least one of the technical problems existing in the prior art. To this end, this application proposes a screening device and its dry granulation equipment to solve the problem that a large amount of dust still adheres to the surface of particles after vibrating screening in current equipment.

[0006] In a first aspect, this application provides a screening device, comprising: a housing, having an inlet, a recovery outlet, and an outlet sequentially arranged along the material flow direction, wherein the inlet and the outlet are opposite to each other, and the axis of the recovery outlet intersects the axis of the outlet; the inlet is used to receive the crushed and granulated material, and the outlet is used to feed material to a vibrating screen; a material curtain forming structure, disposed within the housing, opposite to the inlet, and located above the recovery outlet, the material curtain forming structure being used to disperse falling material into a material curtain; a blower, installed on the inner wall of the housing on one side opposite to the recovery outlet, and located below the material curtain forming structure, and used to blow airflow to the recovery outlet; and a negative pressure dust removal mechanism, comprising a granular material recovery component and a fan connected in sequence, wherein the air inlet of the granular material recovery component is connected to the recovery outlet.

[0007] Based on the aforementioned screening device, during operation, the crushed and granulated material enters the housing through the feed inlet and falls onto the material curtain forming structure. The material curtain forming structure adjusts the material to fall in a curtain shape, fully exposing the particles and dust in the material, providing conditions for subsequent separation. During the material's descent, the blower blows airflow towards the recovery port, while simultaneously, the negative pressure dust removal mechanism generates negative pressure at the recovery port. Together, they form a transverse airflow from the blower to the recovery port. This airflow blows the lighter dust particles in the material curtain to the vicinity of the recovery port, where they are drawn into the granular material recovery component, thus achieving the separation and recovery of dust and particles. The particles, after dust removal, continue to fall, are discharged through the outlet, and enter the next process, such as a vibrating screen. Through this process, dust adhering to the particle surface is effectively removed, improving the final particle quality and facilitating stable operation in subsequent continuous production.

[0008] In one or more embodiments of the screening device described above, a baffle is further included. The baffle is installed on the inner wall of the box body on the same side as the recovery port and is located below the recovery port along the material falling direction. The baffle is inclined and its free end extends into the projection area of ​​the material curtain, and the free end is lower than the fixed end of the baffle.

[0009] In one or more embodiments of the screening device described above, the baffle is rotatably connected to the housing; the screening device further includes a driving member having a driving shaft that extends into the housing and is connected to the baffle to drive the baffle to rotate relative to the inner wall of the housing.

[0010] In one or more embodiments of the screening device described above, the downward-facing side of the baffle is provided with a chute, the chute extends away from the recovery port, and the drive shaft extends into the chute to slide with the baffle.

[0011] In one or more embodiments of the screening device described above, the baffle is detachably connected to the inner wall of the housing.

[0012] In one or more embodiments of the screening device described above, the inner wall of the box, the material curtain forming structure, and the surface of the baffle are provided with an electrostatic conductive layer.

[0013] In one or more embodiments of the screening device described above, the material curtain forming structure is an umbrella-shaped dispersing cone, with the small end of the umbrella-shaped dispersing cone facing the feed inlet; or, the material curtain forming structure is a material distribution plate, with a plurality of through-holes in the material distribution plate, the cross-section of the through-holes being V-shaped.

[0014] In one or more embodiments of the screening device described above, the granular material recovery assembly includes a cyclone separator and a bag filter connected in sequence, the fan being connected to the bag filter, the cyclone separator being used to recover sucked-in particles, and the bag filter being used to collect dust.

[0015] In one or more embodiments of the screening device described above, a lifting support is further included, the lifting support extending at least partially into the housing, the material curtain forming structure being mounted on the lifting support to move along the direction from the discharge port to the inlet under the drive of the lifting support; or, the blower is slidably disposed on the inner wall of the housing along the direction from the inlet to the discharge port.

[0016] In a second aspect, this application provides a dry granulation apparatus, including a screening device as described in the first aspect.

[0017] The above-described one or more embodiments of this application have at least one or more of the following beneficial effects:

[0018] Before operation, the height of the material curtain forming structure can be adjusted using the lifting bracket according to the material properties to optimize the material's falling pattern. Simultaneously, the relative height between the moving blower and the recovery port can be adjusted to regulate the path of the transverse airflow. During operation, the crushed and granulated material enters the chamber through the feed inlet and falls onto the material curtain forming structure. The structure adjusts the material to fall in a curtain shape, fully exposing the particles and dust in the material, providing conditions for subsequent separation. During the material's fall, the blower blows airflow towards the recovery port. Simultaneously, the negative pressure dust removal mechanism generates negative pressure at the recovery port, and together they form a transverse airflow from the blower towards the recovery port. This airflow blows the lighter dust particles in the material curtain to the vicinity of the recovery port, where they are drawn into the granular material recovery component, thus achieving the separation and recovery of dust and particles. The particles, after dust removal, continue to fall, are discharged through the outlet, and enter the next process, such as a vibrating screen. The above process effectively removes dust adhering to the particle surface, improves the final quality of the particles, and facilitates the stable operation of subsequent continuous production.

[0019] Additional aspects and advantages of this application will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of this application. Attached Figure Description

[0020] The disclosure of this application will become more readily understood with reference to the accompanying drawings. It will be readily understood by those skilled in the art that these drawings are for illustrative purposes only and are not intended to limit the scope of protection of this application. Furthermore, similar numbers in the drawings are used to denote similar components, wherein:

[0021] Figure 1 This is a schematic diagram illustrating the structure of a screening device provided in an embodiment of this application;

[0022] Figure 2 This is a bottom view of a screening device provided in an embodiment of this application;

[0023] Figure 3 This is a cross-sectional view of a screening device provided in an embodiment of this application;

[0024] Figure 4 This is a schematic diagram of a material distribution plate provided in an embodiment of this application;

[0025] Figure 5 This is a cross-sectional view of a material distribution plate provided in an embodiment of this application.

[0026] Explanation of reference numerals in the attached figures:

[0027] 1. Box body; 11. Recycling port; 12. Feed inlet; 13. Discharge outlet; 2. Lifting bracket; 21. Support rod; 22. Sleeve; 3. Material curtain forming structure; 31. Umbrella-shaped dispersion cone; 32. Material distribution plate; 321. Strip hole; 4. Blower; 5. Baffle; 51. Free end; 52. Slide groove; 6. Drive component. Detailed Implementation

[0028] Some embodiments of this application are described below with reference to the accompanying drawings. Those skilled in the art should understand that these embodiments are merely illustrative of the technical principles of this application and are not intended to limit the scope of protection of this application.

[0029] Currently, in typical dry granulation equipment, some particles still have a lot of dust adhering to their surface after being vibrated and screened. This not only affects the final quality of the particles, but also has an adverse impact on subsequent continuous production.

[0030] Therefore, this application creatively proposes a screening device and its dry granulation equipment. The screening device includes a housing, a lifting support, a material curtain forming structure, a blower, and a negative pressure dust removal mechanism. During operation, the crushed and granulated material enters the housing through the feed inlet and falls onto the material curtain forming structure. The material curtain forming structure adjusts the material to fall in a curtain shape to form a material curtain, fully exposing the particles and dust in the material, providing conditions for subsequent separation. During the material falling process, the blower blows airflow towards the recovery port. At the same time, the negative pressure dust removal mechanism generates negative pressure at the recovery port, and the two together form a transverse airflow from the blower to the recovery port. This airflow blows the lighter dust in the material curtain to the vicinity of the recovery port, and the dust is sucked into the granular material recovery component through the recovery port, thereby realizing the separation and recovery of dust and particles. The particles after dust removal continue to fall, are discharged through the discharge port, and enter the next process, such as a vibrating screen. The above process effectively removes dust adhering to the particle surface, improves the final quality of the particles, and facilitates the stable operation of subsequent continuous production.

[0031] The present application will be described in detail below through specific embodiments.

[0032] Example 1

[0033] Reference Figures 1 to 5As shown in the figure, this application creatively proposes a screening device, which includes a housing 1, a lifting support 2, a material curtain forming structure 3, a blower 4, and a negative pressure dust removal mechanism (not shown in the figure). The housing 1 is provided with an inlet 12, a recovery port 11, and an outlet 13 along the material flow direction, and the axis of the recovery port 11 intersects the axis of the outlet 13. The inlet 12 is used to receive the crushed and granulated material, and the outlet 13 is used to feed material to the vibrating screen. The material curtain forming structure 3 is located inside the housing 1, opposite to the inlet 12, and above the recovery port 11, and is used to disperse the falling material into a material curtain. The blower 4 is installed on the inner wall of the housing 1 on the side opposite to the recovery port 11, and is used to blow airflow to the recovery port 11. The negative pressure dust removal mechanism includes a granular material recovery component and a fan connected in sequence, and the air inlet of the granular material recovery component is connected to the recovery port 11.

[0034] It is understood that the shape of the housing 1 can be set to any regular or irregular shape, such as a cuboid, cube, or cylinder, as long as it meets the functional requirements of serving as the main framework of the entire screening device and a sealed working chamber. In this embodiment, the housing 1 is cuboid in shape to facilitate the installation and layout of the internal components.

[0035] In some examples, the feed inlet 12 is located at the top of the housing 1 and is sealed to the discharge pipe of the upstream crushing and granulation assembly via a quick-release chuck or flange structure to ensure that material enters the housing 1 in a closed state and prevents dust from overflowing. The discharge outlet 13 is used to feed material to the vibrating screen. It is usually located at the bottom of the housing 1 and may be funnel-shaped to facilitate the collection and discharge of particles. The discharge outlet 13 is also connected to the feed pipe of the downstream vibrating screen via a flexible connection or sealing flange. The recovery port 11 is opened on the side wall of the housing 1 as a channel for the discharge of dust-laden gas.

[0036] In some examples, the screening device also includes a lifting support 2, which extends at least partially into the housing. A material curtain forming structure 3 is mounted on the lifting support 2 to move along the direction from the discharge port 13 to the inlet 12 under the action of the lifting support 2. The fixed end of the lifting support 2 can be installed at the bottom or outside of the housing 1.

[0037] The lifting support 2 can be implemented by any mechanical structure capable of achieving linear lifting motion. This is provided as an example, not a limitation. Figure 2 and Figure 3As shown, the lifting support 2 includes a slidingly fitted support rod 21 and a sleeve 22. The sleeve 22 is fitted onto the support rod 21, and the material curtain forming structure 3 is installed on the sleeve 22. The end of the sleeve 22 away from the material curtain forming structure 3 is connected to the support rod 21 through an elastic sleeve. A threaded hole can be provided on the sleeve 22, and the sleeve 22 can be locked and fixed to the support rod 21 after adjustment to the desired height by screwing in a locking screw or set screw (not shown in the figure). The material curtain forming structure 3 is fixedly installed at the lower end of the sleeve 22. In another optional embodiment, the lifting support 2 can also adopt an automatic adjustment mechanism such as an electric push rod, cylinder, or screw and nut pair to achieve online automatic height adjustment.

[0038] The elastic sleeve ensures that the surface of the support rod 21 is always covered and shielded during the movement of the sleeve 22, thereby preventing dust or particles from adhering to the support rod 21 and preventing the smooth sliding of the lifting bracket 2 from being affected by the adhesion.

[0039] It is understandable that when the lifting support 2 passes through the discharge port 13, it may cause spatial interference with the connecting pipeline of the vibrating screen connected to the discharge port 13. To avoid such interference, in this embodiment, a transmission mechanism (such as a transmission belt or gear set) can be added to shift the installation position or adjustment end of the lifting support 2 to an area away from the connecting pipeline, thereby achieving spatial avoidance. Alternatively, a clearance channel for the lifting support 2 to pass through can be opened in the connecting pipeline between the discharge port 13 and the vibrating screen, and the passage can be sealed to ensure the airtightness of the housing 1. Of course, the lifting support 2 can also be installed inside the housing 1.

[0040] In some examples, the material curtain forming structure 3 is located directly below the feed inlet 12. Its core function is to receive the aggregated columnar mixture of particles and dust falling from the feed inlet 12 and physically disperse it into a material curtain of uniform thickness and appropriate width to increase the contact area between the material and the lateral airflow, thus fully exposing the dust. That is, it can be any mechanical component capable of guiding a concentrated flow of falling material into a dispersed, flat, or annular falling shape.

[0041] As an alternative example, see Figure 3 As shown, the material curtain forming structure 3 is an umbrella-shaped dispersing cone 31. The umbrella-shaped dispersing cone 31 is generally conical, with its small end (tip) facing the feed inlet 12 and its large end (bottom) facing the discharge outlet 13. When the material falls vertically from the feed inlet 12 and impacts the cone surface of the umbrella-shaped dispersing cone 31, the material will spread evenly in all directions along the cone surface, forming a ring-shaped, umbrella-shaped material curtain. The advantage of this structure is that it can fully spread the material, has a large processing capacity, and is not prone to clogging. To optimize the dispersion effect, the cone apex angle is preferably 60° to 90°.

[0042] As another alternative example, see [reference] Figure 4 and Figure 5 As shown, the material curtain forming structure 3 is a distribution plate 32 with multiple through-holes 321. Each through-hole 321 has a V-shaped cross-section, meaning it is wider at the inlet and narrower at the outlet. The distribution plate 32 can be inclined and positioned below the feed inlet 12. When material falls onto the distribution plate 32, it slides downwards along the plate surface and is combed and diverted as it passes through the through-holes 321. After falling from each through-hole 321, it converges into one or more flat, water curtain-like material curtains. This structure is particularly suitable for material flows (i.e., material curtains) falling from the rectangular discharge outlet 13.

[0043] In some examples, the blower 4 can be any nozzle, air knife, or duct structure capable of blowing air. As an example and not a limitation, the blower 4 is a horizontally arranged strip-shaped nozzle with an internal air chamber and one or more rows of air holes on the side facing the recovery port 11. The air inlet of the blower 4 is connected to an external air source (such as compressed air or fan exhaust) via a flexible hose. The hose can be threaded through a through-hole in the housing 1, ensuring a seal between the through-hole and the hose.

[0044] In some examples, the blower 4 is slidably disposed on the inner wall of the housing in the direction from the inlet 12 to the outlet 13.

[0045] To enable the sliding installation of the blower 4, a vertically extending slide rail or groove 52 is provided on the inner wall of the housing 1, and a matching slider is fixed to the back of the blower 4. By moving the blower 4 up and down, the relative height difference between it and the recovery port 11 can be changed, thereby adjusting the flow path and coverage of the transverse airflow to adapt to the position and diffusion width of the material curtain formed by different materials.

[0046] Understandably, a particulate matter recovery unit can be any device capable of separating solid particles or dust from an airflow using principles such as centrifugal force, inertial force, filtration, or electrostatic adsorption.

[0047] As an example, and not a limitation, the granular material recovery assembly includes a cyclone separator and a bag filter connected in sequence. A fan is connected to the bag filter. The cyclone separator recovers the sucked-in particles, and the bag filter collects the dust. During operation, the fan draws air in, creating a negative pressure environment inside both the cyclone separator and the bag filter. The airflow containing dust and a small amount of accidentally sucked-in particles first enters the cyclone separator, where centrifugal force separates and recovers the denser accidentally sucked-in particles from the airflow. This material can be returned to the granulation process. Subsequently, the exhaust gas containing ultrafine dust enters the bag filter, where the dust is intercepted by the filter bags, and the clean air is discharged by the fan. This combination achieves both efficient dust collection and maximizes the recovery of usable materials.

[0048] To further improve the sorting accuracy of the screening device and prevent qualified particles from being accidentally sucked into the recovery port 11 under the action of the transverse airflow, refer to Figure 3 As shown, the screening device also includes a baffle 5 installed inside the box 1. The baffle 5 is installed on the inner wall of the box 1 on the same side as the recovery port 11, and is located below the recovery port 11 in the direction of material falling. The baffle 5 is inclined, and its free end 51 extends into the projection area of ​​the material curtain, and the free end 51 is lower than the fixed end of the baffle 5.

[0049] It is understandable that the end of the baffle 5 connected to the housing 1 is the fixed end, and the other end is the free end 51. The projection area of ​​the material curtain refers to the area covered by the orthographic projection of the material curtain formed by the material curtain forming structure 3 on the horizontal plane during its vertical descent. By extending the free end 51 into this projection area, it can be ensured that the baffle 5 can effectively intercept particles that are horizontally deflected by the lateral airflow. At the same time, the inclined setting of the baffle 5 allows the intercepted particles to slide down the upper surface of the baffle 5 back to the discharge port 13 to avoid material accumulation on the baffle 5; on the other hand, this inclined posture also guides the airflow below the recovery port 11, which helps to form a stable flow field.

[0050] To drive the baffle 5 to rotate, the screening device also includes a driving component 6. The driving component 6 has a driving shaft that extends into the housing 1 and is connected to the baffle 5 to drive the baffle 5 to rotate relative to the inner wall of the housing 1. The driving component 6 can be a power source capable of linear drive, such as an electric cylinder or a pneumatic cylinder.

[0051] Furthermore, in some examples, the downward-facing side of the baffle 5 is provided with a groove 52, which extends away from the recovery port 11. The drive shaft extends into the groove 52 to slide in connection with the baffle 5. The end of the drive shaft may be square, T-shaped, or have a slider structure to prevent it from dislodging from the groove 52.

[0052] As another alternative example, to accommodate the need to change the shape, size, or material of the baffle 5 for different product batches or different material characteristics, the baffle 5 is detachably connected to the inner wall of the box 1.

[0053] The detachable connections include, but are not limited to, threaded connections, snap-fit ​​connections, and plug-in connections. In this embodiment, the inner wall of the housing 1 is provided with a slot or a mounting bracket, and the fixed end of the baffle 5 is provided with a matching insert or hook. After opening one side of the housing 1 (an inspection door can be provided on this side), the operator can directly and manually pull out or insert the baffle 5 from the slot for quick replacement. The replaceable baffle 5 can be a prefabricated part with different tilt angles, or it can be a baffle 5 with different coatings or shapes (such as flat type or serrated type) to meet different process requirements.

[0054] In some examples, to prevent dust or particles from adhering to the inner wall of the housing 1, the material curtain forming structure 3, and the surface of the baffle 5 due to static electricity, thus affecting the separation effect and cleaning, an electrostatic conductive layer is provided on the inner wall of the housing 1, the surface of the material curtain forming structure 3, and the surface of the baffle 5. The electrostatic conductive layer can be any surface with a resistivity of 10... 6 Up to 10 9 A material layer within the Ω / sq range. In this embodiment, the conductive layer is a conductive coating layer sprayed onto the surface of each component, or a carbon fiber composite plate adhered to the surface of each component. This conductive layer is reliably grounded to the equipment casing via wires, enabling timely conduction of accumulated static charge, thereby effectively preventing dust adsorption and ensuring the long-term stable operation of the screening device.

[0055] In addition, an anti-static layer can also be provided on the outer surface of the lifting bracket 2.

[0056] Specifically, before operation, the operator can adjust the material curtain forming structure 3 to a suitable height using the lifting bracket 2, based on the particle size distribution, density, and flowability of the material to be processed, to optimize the material curtain shape after the material falls. At the same time, by sliding and adjusting the position of the blowing component 4, the relative height between it and the recovery port 11 is changed, thereby precisely setting the path of the transverse airflow to ensure that the airflow can effectively penetrate the material curtain.

[0057] During operation, the air source of the blower and the air supply of the blower 4 are activated. The material, after being crushed and granulated upstream, enters the housing 1 through the feed inlet 12 under gravity and falls onto the material curtain forming structure 3. The material is dispersed into a curtain shape and falls evenly, forming a material curtain. During the falling process, the airflow blown out by the blower 4 and the suction effect of the recovery port 11 together form a stable transverse airflow. This airflow passes laterally through the material curtain, blowing the lighter dust particles to the vicinity of the recovery port 11, where they are then sucked into the particulate matter recovery component, completing the separation and recovery of the dust.

[0058] The target particles with larger density and particle size are almost unaffected by the lateral airflow because their gravity settling velocity is greater than the lateral carrying force of the airflow. They continue to fall along the vertical trajectory and are eventually discharged through the discharge port 13 to enter the next process (such as a vibrating screen).

[0059] Through the above-described device and process, this embodiment achieves efficient, online, and selective removal of dust from particulate materials, significantly improving the cleanliness of the final particulate product and facilitating stable operation of subsequent production.

[0060] Example 2

[0061] Corresponding to Embodiment 1 above, this application also provides a dry granulation apparatus, including the screening device described above.

[0062] In this embodiment, the dry granulation equipment further includes a crushing and granulating component and a vibrating screen, with the screening device disposed between the crushing and granulating component and the vibrating screen.

[0063] In the description of this specification, the references to terms such as "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of this application. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0064] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one of that feature. In the description of this application, "multiple" means at least two, such as two, three, etc., unless otherwise explicitly specified.

[0065] Although embodiments of this application have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting this application. Those skilled in the art can make changes, modifications, substitutions and variations to the above embodiments within the scope of this application.

Claims

1. A screening device, characterized in that, include: The box body is provided with a feed inlet, a recovery outlet and a discharge outlet in sequence along the material flow direction, and the feed inlet and the discharge outlet are arranged opposite to each other, and the axis of the recovery outlet intersects the axis of the discharge outlet; The feed inlet is used to receive the crushed and granulated material, and the discharge outlet is used to feed the vibrating screen. A material curtain forming structure is disposed inside the box and is positioned opposite to the feed inlet and above the recovery inlet. The material curtain forming structure is used to disperse the falling material into a material curtain. A blower is installed on the inner wall of the box body on the side opposite to the recycling port, and is located below the material curtain forming structure, and is used to blow airflow to the recycling port; The negative pressure dust removal mechanism includes a particulate matter recovery component and a fan connected in sequence, wherein the air inlet of the particulate matter recovery component is connected to the recovery port.

2. The screening apparatus of claim 1, wherein, It also includes a baffle, which is installed on the inner wall of the box on the same side as the recycling port and is located below the recycling port in the direction of material falling; The baffle is inclined, with its free end extending into the projection area of ​​the material curtain, and the free end being lower than the fixed end of the baffle.

3. The screening apparatus of claim 2, wherein, The baffle is rotatably connected to the box body; The screening device further includes a driving component, which has a driving shaft that extends into the housing and is connected to the baffle to drive the baffle to rotate relative to the inner wall of the housing.

4. The screening apparatus of claim 3, wherein, The downward-facing side of the baffle is provided with a sliding groove, which extends away from the recycling port. The drive shaft extends into the sliding groove to slide and connect with the baffle.

5. The screening apparatus of claim 2, wherein, The baffle is detachably connected to the inner wall of the box.

6. A screening device according to any one of claims 2 to 5, characterised in that, The inner wall of the box, the material curtain forming structure, and the surface of the baffle are provided with an electrostatic conductive layer.

7. The screening apparatus of claim 1, wherein, The material curtain forming structure is an umbrella-shaped dispersion cone, with the small end of the umbrella-shaped dispersion cone facing the feed inlet; or, The material curtain forming structure is a material distribution plate, which has multiple through-holes with V-shaped cross-sections.

8. The screening apparatus of claim 1, wherein, The particulate matter recovery assembly includes a cyclone separator and a bag filter connected in sequence. The fan is connected to the bag filter. The cyclone separator is used to recover the sucked-in particles, and the bag filter is used to collect dust.

9. The screening apparatus of claim 1, wherein, It also includes a lifting bracket, which at least partially extends into the box body, and the material curtain forming structure is mounted on the lifting bracket so as to move along the direction from the discharge port to the inlet under the drive of the lifting bracket; or, The blower is slidably disposed on the inner wall of the box in the direction from the inlet to the outlet.

10. A dry granulation apparatus characterized by, Includes the screening device as described in any one of claims 1 to 9.

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