Graded grinding vertical mill and use method thereof

Abstract

The invention discloses a grading grinding vertical mill and a using method thereof, and relates to the technical field of vertical mills.The grading grinding vertical mill comprises a mill shell, a millstone grading rotor and an eddy current restraining flow guide cover assembly, the grading rotor is fixedly installed on the upper portion of the inner wall of the mill shell, and a millstone is fixed below the grading rotor; and a vortex suppression flow guide cover assembly is fixedly mounted on the inner wall of the mill shell and located on the periphery of the grading rotor, and the vortex suppression flow guide cover assembly is used for guiding airflow to uniformly and stably flow to a blade area of the grading rotor. According to the invention, the eddy current suppression flow guide cover assembly is mounted, so that active suppression of three-dimensional turbulence in a classification area is realized, the problems of over-grinding of fine powder and running of coarse particles caused by airflow turbulence induced by a high-speed rotor are solved, the classification precision is improved, and the classification power consumption is reduced.

Description

Technical Field

[0001] The invention relates to the technical field of vertical mills, in particular to a graded powder grinding vertical mill and a use method thereof. Background Art

[0002] With the large-scale development of the building materials, metallurgy and non-metallic mineral processing industries, the requirements for energy efficiency and product fineness control of grinding equipment are increasing. Vertical mills, due to their integrated advantages of grinding, drying and sorting, have gradually replaced traditional ball mill systems and become mainstream equipment. They are especially widely used in the preparation of cement raw materials, slag powder and coal powder. Further reducing grinding power consumption and improving the fineness qualification rate have become core technical directions that the industry urgently needs to break through.

[0003] Although the current built-in grading vertical mill has simplified the process flow by integrating grinding and sorting functions, its core grading area has significant technical defects: the high-speed rotating grading rotor induces strong air vortexes, resulting in a turbulent flow field. Fine powder is repeatedly ground due to turbulence, and coarse particles are mixed into the finished product due to insufficient centrifugal force. The existing guide structure is mostly a simple static baffle, which cannot effectively suppress three-dimensional turbulence, resulting in a contradiction between grading accuracy and system energy consumption. Increasing the rotor speed can improve fineness but greatly increase power consumption, while reducing the speed leads to uncontrolled particle size. At the same time, problems such as uneven airflow distribution at the edge of the grinding disc and chaotic initial state of material lifting further aggravate the loss of grading efficiency and restrict breakthroughs in the comprehensive performance of the equipment.

[0004] Patent CN105642407B discloses a vertical grinding mill, which enables the simultaneous production of products of various particle sizes.

[0005] The above-mentioned patent includes a base, a grinding mechanism mounted on the base, and an airflow classifier. The airflow classifier includes a body and multiple rotors mounted upright on the body. The rotors include blades. The rotors are divided into two or more groups. The blade gaps and / or rotational speeds of the rotors in different groups are different, so as to pass products of different particle sizes. Each group of rotors passes products of the same particle size and is connected to the same discharge pipe. In the airflow classifier of a vertical mill, the rotors are divided into two or more groups according to the blade gaps and / or rotational speeds. Each group of rotors is connected to the same discharge pipe. The blade gaps and / or rotational speeds of the rotors in different groups are different. The particle sizes of the products passing through the rotors are different, and multiple particle size products can be obtained simultaneously. However, the above-mentioned patent still has room for improvement in addressing airflow turbulence.

[0006] To this end, the present application proposes a vertical mill for graded powder grinding capable of achieving stable airflow and a method for using the same. Summary of the Invention

[0007] The object of the present invention is to provide a graded powder grinding vertical mill and a method of using the same, so as to solve the technical problem of air flow turbulence raised in the above background technology.

[0008] To achieve the above-mentioned object, the present invention provides the following technical solution: a vertical mill for graded powder grinding, comprising a mill housing, a grinding disc graded rotor, and a vortex suppression shroud assembly, wherein the graded rotor is fixedly mounted on the upper portion of the inner wall of the mill housing, the grinding disc is fixed below the graded rotor, and the vortex suppression shroud assembly is fixedly mounted on the inner wall of the mill housing at the periphery of the graded rotor, the vortex suppression shroud assembly being used to guide airflow to flow more evenly and stably toward the graded rotor blade area;

[0009] The vortex suppression guide cover assembly includes: a fixing ring, guide vanes and a straightening grid;

[0010] The fixed ring is mounted on the inner wall of the mill housing through supporting ribs. A number of guide vanes are evenly distributed circumferentially on the inner wall of the fixed ring. Each guide vane extends from the fixed ring toward the grading rotor, and a gradually converging-diverging flow channel is formed between adjacent guide vanes. The rectifying grid is fixedly mounted on the inner wall of the fixed ring and is located at the end of the guide vane.

[0011] Preferably, a driving shaft is fixedly installed at the bottom center of the mill housing, and a spreading plate is fixedly connected to the top end of the driving shaft, and the spreading plate is located directly above the grinding disc.

[0012] Preferably, a curved material lifting guide plate is fixedly installed on the inner wall of the mill housing above the edge of the working surface of the grinding disc. The curved material lifting guide plate is a curved plate uniformly distributed along the circumference, and the curved concave surface faces the center of the grinding disc.

[0013] Preferably, a stepped air guide cone is installed above the spreading plate, and the stepped air guide cone is fixedly installed on the central axis of the mill housing through a bracket, and is located between the spreading plate and the vortex suppression guide cover assembly.

[0014] Preferably, a plurality of material strips are fixed to the surface of the material spreading disk, and the plurality of material strips are arranged in a circular array on the surface of the material spreading disk, and the height of each material strip increases from the center of the material spreading disk to the edge.

[0015] Preferably, a penetrating air guide groove is provided at the bottom of the curved material lifting guide plate, and the air guide groove is distributed along the circumference of the curved material lifting guide plate.

[0016] Preferably, the outer surface of the stepped air guide cone is a multi-step stepped curved surface, the end with the largest diameter is arranged downward, and the central axis of the stepped air guide cone is coaxial with the drive shaft.

[0017] Preferably, the outer wall of the mill housing is fixedly equipped with a through raw material inlet and finished product outlet. The raw material inlet is located in the middle of the mill housing and extends obliquely above the grinding disc. The finished product outlet is located at the top of the mill housing and extends obliquely above the grading rotor. The outer wall of the mill housing is fixedly equipped with a through air inlet.

[0018] Preferably, the method of use comprises the following steps:

[0019] S1. Equipment startup preparation: Connect the external hot air source through the air inlet on the outer wall of the mill shell and supply air to the air ring;

[0020] S2. Raw material input and initial grinding: The bulk material is input from the raw material inlet and falls onto the working surface of the rotating grinding disc;

[0021] S3. Airflow classification control: adjust the speed of the classification rotor to control the fineness of the finished product and observe the state of the finished product outlet material;

[0022] S4. Shutdown maintenance operation: turn off the hot air source and grading rotor, and clean the residual material layer on the grinding disc.

[0023] Preferably, the method of use further comprises the following steps:

[0024] S11, start the driving shaft to drive the spreading disc to rotate, and confirm that the material strips evenly spread the material onto the grinding disc;

[0025] S21, the air flow passes through the air guide groove of the curved lifting guide plate to form an air curtain to prevent material accumulation;

[0026] S31, stepped air guide cone breaks up the central vortex and evenly distributes radial flow velocity;

[0027] S41. Remove the supporting ribs of the fixed ring, check the dust accumulation in the guide vane flow path and clean it.

[0028] Compared with the prior art, the present invention has the following beneficial effects:

[0029] 1. The present invention achieves active suppression of three-dimensional turbulence in the classification zone by installing an eddy current suppression guide cover assembly, solving the problem of fine powder over-grinding and coarse particles running out due to airflow turbulence induced by the high-speed rotor, thereby improving classification accuracy and reducing classification power consumption;

[0030] 2. The present invention achieves deep rectification and homogenization of the rising airflow by installing a stepped air guide cone, solving the problems of uneven velocity distribution and material concentration segregation caused by the central vortex of traditional vertical mills. It also improves the uniformity of the gas-solid flow entering the classification zone and enhances the turbulence suppression efficiency of the vortex suppression guide cover assembly.

[0031] 3. The present invention achieves precise control of the material lifting direction by installing a curved material lifting guide plate, solves the initial turbulence problem caused by the material hitting the cylinder wall when it separates from the edge of the grinding disc, and improves the initial stability of the gas-solid two-phase flow;

[0032] 4. The present invention realizes radial uniform dispersion of the grinding material on the grinding disc by installing a spreading disc, solves the problem of uneven material layer thickness caused by the traditional flat spreading disc, and improves the grinding efficiency and the particle size consistency of the material carried by the airflow. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] Figure 1 It is a schematic diagram of the overall structure of the present invention;

[0034] Figure 2 It is a schematic diagram of the cross-sectional structure of the present invention;

[0035] Figure 3 It is a schematic diagram of the fixing ring structure of the present invention;

[0036] Figure 4 This is a schematic diagram of the guide blade structure of the present invention;

[0037] Figure 5 It is a schematic diagram of the grinding disc structure of the present invention;

[0038] Figure 6 It is a schematic diagram of the stepped air guide cone structure of the present invention.

[0039] In the figure: 1. Mill housing; 2. Grinding disc; 3. Classifying rotor; 4. Retaining ring; 5. Guide vane; 6. Rectifier grid; 7. Support ribs; 8. Drive shaft; 9. Spreading disc; 10. Material stripping bar; 11. Curved lifting guide plate; 12. Air guide groove; 13. Stepped air guide cone; 14. Bracket; 15. Raw material inlet; 16. Finished product outlet; 17. Air inlet. DETAILED DESCRIPTION

[0040] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0041] In the description of the present invention, it should be noted that the terms "upper," "lower," "inner," "outer," "front end," "rear end," "both ends," "one end," "the other end," and the like, indicating orientations or positional relationships, are based on the orientations or positional relationships shown in the accompanying drawings and are intended solely to facilitate and simplify the description of the present invention. They are not intended to indicate or imply that the devices or components referred to must have, be constructed, or operate in a specific orientation, and therefore should not be construed as limiting the present invention. Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0042] In the description of the present invention, it should be noted that, unless otherwise expressly specified or limited, the terms "installed," "provided with," "connected," etc., should be understood in a broad sense. For example, "connected" may refer to a fixed connection, a detachable connection, or an integral connection; it may refer to a mechanical connection or an electrical connection; it may refer to a direct connection or an indirect connection through an intermediate medium; it may refer to internal communication between two components. Those skilled in the art will be able to understand the specific meanings of the above terms in the present invention based on specific circumstances.

[0043] See also Figure 1 、 Figure 3 、 Figure 4 and Figure 5 The present invention provides an embodiment of a vertical mill for graded powder grinding, comprising a mill housing 1, a grinding disc 2, a grading rotor 3, and a vortex suppression guide cover assembly. The vortex suppression guide cover assembly is fixed to the inner wall of the mill housing 1 via supporting ribs 7 and surrounds the grading rotor 3. The vortex suppression guide cover assembly is composed of a fixing ring 4, guide vanes 5, and a rectifying grid 6. The guide vanes 5 are circumferentially distributed on the inner wall of the fixing ring 4 to form a gradually converging and gradually diverging flow channel. The rectifying grid 6 is fixed to the end of the guide vanes 5. The gradually converging and gradually diverging flow channel forces the airflow to be laminar, reduces the turbulence intensity in the grading zone, and reduces the over-grinding rate of fine powder.

[0044] Furthermore, when the rising airflow carrying material particles enters the annular space between the fixed ring 4 and the classifying rotor 3, it is first accelerated by the tapered flow channel formed by the guide vanes 5. The airflow is compressed and guided along the curved surface contour of the guide vanes 5, and the large-scale vortices are peeled off. Then the airflow enters the gradually diverging flow channel to decelerate and diffuse, and the kinetic energy is converted into pressure energy, which suppresses the dissipation of turbulent kinetic energy. Finally, the airflow passes through the rectifying grid 6, and the residual micro-vortices are cut and broken by the capillary effect, forming an axially uniform laminar flow field acting on the blade area of ​​the classifying rotor 3. When the classifying rotor 3 rotates in a laminar flow environment, the centrifugal force and the airflow drag force on the particles are evenly distributed. The coarse particles are accurately thrown to the inner wall of the mill housing 1 and fall back to the grinding disc 2, while the fine particles stably pass through the gap between the blades of the classifying rotor 3 and are output through the finished product outlet at the top of the mill housing 1, thereby reducing the over-grinding rate and the coarse running rate.

[0045] See also Figure 1 、 Figure 3 、 Figure 4 and Figure 5The present invention provides an embodiment of a vertical mill for graded powder grinding, comprising a mill housing 1, a grinding disc 2, a grading rotor 3, and an eddy current suppression guide cover assembly. The eddy current suppression guide cover assembly is fixed to the inner wall of the mill housing 1 through supporting ribs 7, surrounding the grading rotor 3. The guide cover assembly is composed of a fixing ring 4, guide vanes 5, and a rectifying grid 6. The guide vanes 5 are circumferentially distributed on the inner wall of the fixing ring 4 to form a gradually converging and diverging flow channel. The rectifying grid 6 is fixed to the end of the guide vanes 5. A spreading disc 9 is located directly above the grinding disc 2. A circumferential array of stripping strips 10 is provided on the disc surface. The height of the stripping strips 10 increases from the disc center to the edge. The gradient design of the stripping strips 10 improves the uniformity of material spreading. In combination with the guide cover assembly, the particle size of the airflow-carried material is made consistent.

[0046] Furthermore, when the driving shaft 8 drives the spreading disc 9 to rotate, the material strips 10 of the circular array on the disc surface evenly scatter the material put into the raw material inlet 15 to the working surface of the grinding disc 2. The material flow lifted by the edge of the grinding disc 2 hits the concave surface of the curved lifting guide plate 11, and changes the direction of movement under the buffering of the air curtain formed by the air guide groove 12, forming a concentrated upward gas-solid two-phase flow. When the airflow passes through the multi-step stepped surface of the stepped air guide cone 13, the central high-speed jet is diffused and the edge low-speed area is accelerated. The uniform airflow after breaking the vortex carries the material up to the vortex suppression guide cover component area. At this time, the airflow passes through the gradually converging and expanding flow channel formed by the guide blades 5 in turn, the turbulent kinetic energy is attenuated, and the rectifying grid 6 further eliminates the residual vortex. Finally, the stable laminar flow reaches the blade area of ​​the grading rotor 3. Under the action of the centrifugal field of the grading rotor 3, the qualified fine powder is discharged through the blade area, and the coarse particles fall back along the inner wall of the mill shell 1 to the grinding disc 2 for re-grinding, realizing continuous and efficient graded grinding.

[0047] See also Figure 1 、 Figure 3 、 Figure 4 and Figure 5 The present invention provides an embodiment of a vertical mill for graded powder grinding, comprising a mill housing 1, a grinding disc 2, a grading rotor 3, and a vortex suppression guide cover assembly. The vortex suppression guide cover assembly is fixed to the inner wall of the mill housing 1 through supporting ribs 7 and surrounds the grading rotor 3. The guide cover assembly is composed of a fixing ring 4, guide vanes 5, and a rectifying grid 6. The guide vanes 5 are evenly distributed circumferentially on the inner wall of the fixing ring 4 to form a gradually converging-diverging flow channel. The rectifying grid 6 is fixed to the end of the guide vanes 5. A curved material lifting guide plate 11 is installed above the edge of the grinding disc 2. The guide plate is 12 S-shaped curved plates evenly distributed circumferentially, with the concave surface facing the center of the grinding disc. An air guide groove 12 is provided at the bottom thereof. The airflow ejected from the air guide groove 12 forms an air curtain, which reduces the material wall adhesion rate and attenuates the initial turbulent energy.

[0048] Furthermore, the block material is put into the mill housing 1 through the raw material inlet 15 and falls onto the working surface of the rotating grinding disc 2. The material moves toward the edge of the grinding disc 2 under the action of centrifugal force. At this time, 200-300℃ hot air enters the mill housing 1, and the high-speed air flow is ejected upward through the wind ring at the edge of the grinding disc 2, lifting the ground material particles. The rising material flow first hits the curved surface of the curved lifting guide plate 11. Under the buffering of the thick air curtain layer ejected by the air guide groove 12, the movement direction of the material particles is forced to be adjusted vertically upward to avoid directly hitting the inner wall of the mill housing 1. The pre-rectified material flow continues to rise to the stepped air guide cone 13 area, and its three-level stepped surface diffuses the central high-speed jet outward, eliminating Except for the central vortex zone, the homogenized gas-solid two-phase flow then enters the converging-diverging flow channel of the vortex suppression guide cover assembly. Under the constraint of the guide vane 5, the air flow velocity increases in the converging section, and the kinetic energy is converted into pressure energy in the diverging section. The turbulence intensity is attenuated by 40%. Finally, the air flow passes through the honeycomb pores of the rectifying grid 6, and the residual vortex is broken into micro-scale turbulence, forming a laminar flow state and entering the blade area of ​​the classifying rotor 3. At this time, the classifying rotor 3 rotates at high speed to generate a centrifugal force field. The particles that meet the fineness requirements pass through the gaps between the blades of the classifying rotor 3 under the action of the airflow drag force. The coarse particles hit the inner wall of the fixed ring 4 under the action of the centrifugal force and fall down, and return to the grinding disc 2 along the reflux channel formed by the guide vane 5 for further grinding.

[0049] See also Figure 1 、 Figure 3 、 Figure 4 、 Figure 5 and Figure 6 The present invention provides an embodiment of a vertical mill for graded powder grinding, comprising a mill housing 1, a grinding disc 2, a grading rotor 3, and a vortex suppression shroud assembly. The vortex suppression shroud assembly is fixed to the inner wall of the mill housing 1 via support ribs 7 and surrounds the grading rotor 3. The vortex suppression shroud assembly comprises a fixing ring 4, guide vanes 5, and a rectifying grid 6. The guide vanes 5 are circumferentially distributed on the inner wall of the fixing ring 4 to form a gradually converging and diverging flow channel. The rectifying grid 6 is fixed to the end of the guide vanes 5. A stepped air guide cone 13 is installed above the spreading plate 9. The air guide cone is fixed to the central axis of the mill via a bracket 14. The outer surface of the air guide cone is a three-step stepped surface, with the maximum diameter end facing downward and coaxial with the drive shaft 8. The stepped surface breaks up the central vortex, reducing the radial flow velocity difference from ±35% to ±8%, and improving the inflow uniformity of the shroud assembly 1 to 92%.

[0050] Furthermore, when the driving shaft 8 drives the grinding disc 2 to rotate, the material on the edge of the grinding disc 2 is lifted by the air flow of the wind ring and hits the curved material lifting guide plate 11. The air flow ejected from the air guide groove 12 forms an air curtain to prevent material accumulation. The material deflects toward the center along the curved surface, and the rising gas-solid flow is rectified by the three-stage stepped surface of the stepped air guide cone 13. The high-speed air flow in the center diffuses outward, and the flow velocity in the low-speed area at the edge is increased. The air flow that breaks the vortex evenly enters the gradually converging and gradually expanding flow channel formed by the guide blades 5. The compressed air flow in the gradually converging section accelerates laminar flow, and the flow velocity in the gradually expanding section decreases and stabilizes the flow state. The rectified air flow carries the material particles through the honeycomb holes of the rectifying grid 6, breaks the residual vortex and enters the action area of ​​the grading rotor 3. The grading rotor 3 rotates to generate a centrifugal force field. Qualified fine powder passes through the rotor blades under the action of the balanced air flow drag, and the coarse powder hits the inner wall of the fixed ring 4 under the action of the centrifugal force and falls, and returns to the grinding disc 2 through the gap between the guide blades 5 for re-grinding, thereby achieving the coordinated optimization of grading accuracy and energy consumption.

[0051] See also Figure 1 、 Figure 3 、 Figure 4 、 Figure 5 and Figure 6 The present invention provides an embodiment of a vertical mill for graded powder grinding, comprising a mill housing 1, a grinding disc 2, a grading rotor 3, and a vortex suppression guide cover assembly. The vortex suppression guide cover assembly is fixed to the inner wall of the mill housing 1 through supporting ribs 7 and surrounds the grading rotor 3. The guide cover assembly is composed of a fixing ring 4, guide vanes 5, and a rectifying grid 6. The guide vanes 5 are evenly distributed circumferentially on the inner wall of the fixing ring 4 to form a gradually converging and gradually diverging flow channel. The rectifying grid 6 is fixed to the end of the guide vanes 5. A stepped air guide cone 13 is fixed to the central axis of the mill housing through a bracket 14. The outer surface of the stepped air guide cone 13 is designed as a three-level stepped curved surface with the maximum diameter end facing downward and coaxial with the drive shaft 8. The height of the material strips 10 on the surface of the spreading disc 9 increases from the center to the edge of the disc. The stepped curved surface breaks the central vortex, thereby improving the radial distribution uniformity of the airflow to 92%. The gradient distribution of the material strips 10 works synergistically with the stepped air guide cone 13 to achieve a material dispersion uniformity of 95% and reduce the over-grinding rate by 15%.

[0052] Furthermore, after the block material is ground by the grinding disc 2, it is captured by the rotating spreading disc 9 stripping strips 10. Since the height of the stripping strips 10 increases from the center of the disc to the edge, the material is thrown outward along the gradient rising stripping strips 10 under the action of centrifugal force, forming a uniformly dispersed material curtain. When the rising hot air flow carries the powder through the three-level stepped surface of the stepped air guide cone 13, its structure with the maximum diameter end facing downward diffuses the central high-speed air flow outward. At the same time, the stepped surface breaks up the vortex group, so that the radial flow velocity distribution uniformity is increased to 92%, and the gas-solid two-phase is homogenized. The flow then enters the gradually converging and diverging flow channel of the vortex suppression guide cover assembly. The guide vanes 5 force the turbulent airflow to turn into laminar flow, and the material particles complete the final directional flow in the honeycomb channels of the rectifying grid 6. At this time, the blades of the grading rotor 3 apply precise centrifugal classification to the material in the uniform flow state. The coarse particles fall back along the inner wall of the fixed ring 4 to the grinding disc 2 for further grinding, and the fine powder passes through the rectifying grid 6 to become the finished product. The gradient dispersion of the material strip 10 and the rectification of the stepped air guide cone 13 work together to make the material dispersion uniformity reach 95%, and the over-grinding rate is reduced by 15%.

[0053] Working principle: First, bulk materials are put into the mill housing 1 through the inclined raw material inlet 15 and fall to the working surface of the rotating grinding disc 2 for primary crushing. At the same time, external hot air is introduced through the air inlet 17 to form an upward airflow. The drive shaft 8 drives the spreading disc 9 to rotate at high speed. The material strips 10 arranged in a circular array on the disc surface increase in height from the center to the edge, and the crushed materials are evenly scattered to the edge area of ​​the grinding disc 2. At this time, the curved lifting guide plate 11 above the edge of the grinding disc 2 guides the material lifting direction through the concave curvature, and the air guide groove 12 running through the bottom of the plate sprays air to form an air curtain to prevent material accumulation, ensuring that the material enters the rising airflow with a stable trajectory;

[0054] Next, the airflow carrying the powder passes through the stepped air guide cone 13 installed above the spreading plate 9, which is fixed to the central axis of the mill housing 1 through a bracket 14, and the maximum diameter end of the multi-level stepped surface on the outer surface is set downward, coaxial with the drive shaft 8. The stepped surface diffuses the central high-speed airflow outward, breaks up the vortex cluster, and makes the radial flow velocity uniform. The homogenized gas-solid two-phase flow continues to rise to the vortex suppression guide cover assembly area, and the airflow enters the gradually converging and expanding flow channel formed by the guide blade 5 supported by the fixing ring 4. The adjacent blades force the turbulent airflow to turn into laminar flow; then it flows through the honeycomb holes of the rectifying grid 6 to complete the final directional rectification. The stable airflow carries the material particles into the blade area of ​​the grading rotor 3, and achieves precise sorting under the action of centrifugal force;

[0055] Finally, the coarse particles after sorting fall back to the grinding disc 2 along the inner wall of the fixed ring 4 under the action of centrifugal force and are further ground. The qualified fine powder passes through the rectifying grid 6, rises to the top of the mill with the air flow, and is discharged through the inclined and extended finished product outlet 16. During the grading process, the fineness is controlled by adjusting the speed of the grading rotor 3, and the supporting ribs 7 ensure the structural stability of the air guide cover assembly under high-speed airflow, forming a closed-loop grinding-grading process.

[0056] It will be apparent to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above and that the invention can be embodied in other specific forms without departing from the spirit or essential characteristics of the invention. Therefore, the embodiments should be considered in all respects as illustrative and non-restrictive, and the scope of the invention is defined by the appended claims, not the foregoing description, and all variations within the meaning and range of equivalents of the claims are intended to be included therein. Any reference sign in a claim should not be construed as limiting the claim to which it relates.

Claims

1. A vertical mill for graded grinding, characterized by: The invention comprises a mill housing (1), a grinding disc (2), a grading rotor (3) and a vortex suppression shroud assembly, wherein the grading rotor (3) is fixedly mounted on the upper portion of the inner wall of the mill housing (1), the grinding disc (2) is fixed below the grading rotor (3), and the vortex suppression shroud assembly is fixedly mounted on the inner wall of the mill housing (1) at the periphery of the grading rotor (3), and the vortex suppression shroud assembly is used to guide airflow to flow evenly and stably to the blade area of ​​the grading rotor (3); The vortex suppression guide cover assembly comprises: a fixing ring (4), guide vanes (5) and a rectifying grid (6); The fixed ring (4) is mounted on the inner wall of the mill housing (1) via supporting ribs (7). A plurality of guide vanes (5) are evenly distributed circumferentially on the inner wall of the fixed ring (4). Each guide vane (5) extends from the fixed ring (4) toward the grading rotor (3), and a gradually converging-diverging flow channel is formed between adjacent guide vanes (5). The rectifying grid (6) is fixedly mounted on the inner wall of the fixed ring (4) and is located at the end of the guide vane (5).

2. A graded powder grinding vertical mill according to claim 1, characterized in that: A driving shaft (8) is fixedly mounted at the center of the bottom of the mill housing (1), and a spreading disc (9) is fixedly connected to the top of the driving shaft (8), and the spreading disc (9) is located directly above the grinding disc (2).

3. The vertical mill for graded powder grinding according to claim 1, characterized in that: A curved material lifting guide plate (11) is fixedly mounted on the inner wall of the mill housing (1) above the edge of the working surface of the grinding disc (2). The curved material lifting guide plate (11) is a curved plate uniformly distributed along the circumference, and the concave surface of the curved surface faces the center of the grinding disc (2).

4. The vertical mill for graded powder grinding according to claim 2, characterized in that: A stepped air guide cone (13) is installed above the spreading disc (9). The stepped air guide cone (13) is fixedly installed on the central axis of the mill housing (1) through a bracket (14) and is located between the spreading disc (9) and the vortex suppression guide cover assembly.

5. The vertical mill for graded powder grinding according to claim 2, characterized in that: The surface of the material spreading plate (9) is fixed with a plurality of material strips (10), which are arranged in a circular array on the surface of the material spreading plate (9), and the height of each material strip (10) increases from the center of the material spreading plate (9) to the edge.

6. The vertical mill for graded powder grinding according to claim 3, characterized in that: The bottom of the curved material lifting guide plate (11) is provided with a penetrating air guide groove (12), and the air guide groove (12) is distributed along the circumference of the curved material lifting guide plate (11).

7. The vertical mill for graded powder grinding according to claim 4, characterized in that: The outer surface of the stepped air guide cone (13) is a multi-step stepped curved surface, with the end with the largest diameter facing downward, and the central axis of the stepped air guide cone (13) is coaxial with the drive shaft (8).

8. The vertical mill for graded powder grinding according to claim 1, characterized in that: A raw material inlet (15) and a finished product outlet (16) are fixedly mounted on the outer wall of the mill housing (1). The raw material inlet (15) is located in the middle of the mill housing (1) and extends obliquely above the grinding disc (2). The finished product outlet (16) is located at the top of the mill housing (1) and extends obliquely above the classifying rotor (3). An air inlet (17) is fixedly mounted on the outer wall of the mill housing (1).

9. A method for using a graded powder grinding vertical mill, applicable to the graded powder grinding vertical mill according to any one of claims 1 to 8, characterized in that: The method of use comprises the following steps: S1. Equipment startup preparation: connect the external hot air source through the air inlet (17) on the outer wall of the mill housing (1) and supply air to the air ring; S2. Raw material input and initial grinding: Lump materials are input from the raw material inlet (15), and the materials fall onto the working surface of the rotating grinding disc (2); S3, airflow classification control: adjust the speed of the classification rotor (3) to control the fineness of the finished product, and observe the material state at the finished product outlet (16); S4. Maintenance operation: turn off the hot air source and the grading rotor (3), and clean the residual material layer on the grinding disc (2).

10. The method for using a graded grinding vertical mill according to claim 9, characterized in that: The method of use further comprises the following steps: S11, start the driving shaft (8) to drive the spreading disc (9) to rotate, and confirm that the material stripping strip (10) evenly spreads the material onto the grinding disc (2); S21, the air flow passes through the air guide groove (12) of the curved lifting guide plate (11), forming an air curtain to prevent material accumulation; S31, stepped air guide cone (13) breaks the central vortex and evens out the radial velocity distribution; S41. Remove the support ribs (7) of the fixing ring (4), check the dust accumulation condition of the flow passage of the guide vane (5) and clean it.

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