Low energy consumption external circulation cement vertical roller mill and method of using same

Abstract

This invention relates to the field of cement grinding technology, specifically a low-energy external circulation vertical roller mill for cement and its usage method. It includes a mixing and feeding device installed inside the mill. An external circulation elevator discharges the ground material from the grinding mechanism to the outside of the mill for external circulation. The material is then mechanically lifted and fed into a low-resistance, high-efficiency classifier located above the grinding mechanism. The external circulation elevator and the low-resistance, high-efficiency classifier separate the grinding and grading functions of a traditional internal circulation vertical cement mill. The material is mechanically lifted into the low-resistance, high-efficiency classifier for horizontal airflow gradient grading of coarse and fine particles. The mechanical lifting reduces the power consumption of the circulating fan. During grading, the airflow is horizontal and tangential, significantly reducing the energy consumption of gas-carrying material transport. Only a small amount of ventilation is needed inside the vertical mill to stabilize the material layer and collect dust. The pressure head and airflow of the system's circulating fan are significantly reduced, truly achieving energy saving and consumption reduction.

Description

Technical Field

[0001] This invention relates to the field of cement grinding technology, specifically to a low-energy external circulation vertical roller mill for cement and its usage method. Background Technology

[0002] Vertical roller mills, also known as vertical mills, are a type of high-efficiency material grinding equipment that integrates crushing, grinding, pneumatic conveying, in-mill drying, grading, and sorting. They are widely used in industries such as cement, power, non-metallic minerals, and industrial waste treatment. They use a rotating grinding disc to drive the grinding rollers to move relative to each other. The particles form a material layer under the centrifugal force of the grinding disc and are subjected to strong extrusion force generated by the swinging of the grinding rollers driven by a hydraulic cylinder. The material is crushed by multiple compressions and shearings during the rolling of the grinding rollers, resulting in a product with good sphericity. Therefore, vertical mills are widely accepted and used as grinding equipment for producing fine or ultrafine powders.

[0003] Currently, mainstream vertical mills can be divided into internal circulation and external circulation types based on their material circulation methods. The traditional internal circulation vertical mill's workflow is as follows: newly fed material is ground by the grinding disc and rollers, and then thrown to the air ring under the centrifugal force of the grinding disc. It is then blown up by a high-speed hot airflow drawn from the bottom of the mill for pneumatic lifting. The blown-up material enters the dynamic classifier integrated at the top of the mill for sorting. Finished products with qualified fineness are carried out by the airflow and collected by the dust collector; coarse particles return to the grinding disc for further grinding under gravity or mechanical action, while large particles that are not blown up by the airflow fall to the bottom of the mill, are scraped out by the scraper, and returned to the mill via an external bucket elevator. However, the above internal circulation mode has the following drawbacks: high energy consumption, severe wear, stringent requirements for sealing, and difficulty in controlling the stability of the material layer.

[0004] The basic idea of ​​external circulation vertical mill technology is to discharge most of the ground material mechanically and send it to a separate classifier for sorting, with only a small amount of fine powder or gas circulating inside the mill. Although the existing external circulation technology reduces the burden of pneumatic lifting, it still has the following shortcomings:

[0005] 1. Low efficiency of grading system: The common solution is to use a combination of "V-type classifier (V-type classifier) ​​+ high-efficiency dynamic classifier". V-type classifier mainly relies on material impact dispersion and gravity air separation. Its internal air velocity is low, which has limited effect on breaking up materials that are easy to agglomerate after grinding. The pre-grading efficiency is low, which may lead to a large load on the subsequent dynamic classifier. It still requires a large air volume for pneumatic conveying and separation, and the reduction of system air volume and resistance is not obvious.

[0006] 2. Overall energy saving effect is not significant: Since the grading efficiency has not been fundamentally improved, the energy consumption of the fan may still be high, and the energy saving effect of the grinding system is not significant.

[0007] Therefore, the present invention provides a low-energy external circulation vertical roller mill for cement and its usage method, which significantly reduces the energy consumption of the grinding system while improving the operational stability and service life of the equipment, while ensuring product quality. Summary of the Invention

[0008] To address the problems of high energy consumption and low grading efficiency in existing technologies, this invention provides a low-energy external circulation vertical roller mill for cement and its usage method.

[0009] The technical solution adopted by the present invention to solve its technical problem is: a low-energy external circulation cement vertical roller mill, including a mixing and feeding device installed inside the mill, and a grinding mechanism installed at the bottom of the mixing and feeding device. The grinding mechanism includes a shell and a grinding disc assembly installed inside the shell. An external circulation elevator fixed on the foundation is installed on the outside of the grinding mechanism. The inlet of the external circulation elevator is connected to the outlet of the grinding mechanism. The grinding material in the grinding mechanism is discharged to the outside of the grinding mechanism for external circulation through the external circulation elevator. The material is then fed into a low-resistance high-efficiency classifier located above the grinding mechanism by mechanical lifting.

[0010] The mixing and feeding device is configured to receive and mix the newly fed raw materials with the recycled material from the low-resistance high-efficiency classifier, and feed the mixture into the center of the grinding disc assembly of the grinding mechanism.

[0011] The low-resistance high-efficiency air classifier is fixedly connected to the outer shell of the grinding mechanism. A set of feeding ports on its top is connected to the discharge port of a set of feed bins of the external circulation elevator. An air outlet on one side of its top is connected to a dust collector. The prepared material is fluidized and dispersed in the stratified fluidized dispersion chamber located in the middle of the low-resistance high-efficiency air classifier. The shear force of the horizontal velocity gradient is used to break up the particle agglomeration. The material enters the strong swirling classification zone and the forced eddy classification zone. In the swirling and eddy fields, the material is centrifugally settled and classified according to particle size, so as to realize the classification treatment of coarse and fine particles.

[0012] The low-resistance high-efficiency air classifier also includes a sorting shell located in the middle of the air classifier. A primary air inlet is located on the lower periphery of the sorting shell, tangentially arranged in a group and evenly distributed. An air outlet shell is fixedly connected to the top of the sorting shell via flanges and bolts. A lower shell is located below the sorting shell, including a lower air ring at the top. The sorting shell has a double-layer cylindrical structure. An air outlet is fixedly connected to one side of the top of the air outlet shell, forming a 30° angle with the horizontal plane. A group of evenly distributed feed ports are fixedly connected to the bottom plate of the air outlet shell. The lower shell is fixedly connected to the lower part of the sorting shell and the outer shell of the grinding mechanism. A fixed connection is established, which, together with the sorting housing, forms a secondary air inlet. A transmission device is fixedly connected to the top of the air outlet housing. The transmission device consists of a variable frequency motor, a reducer, a shaft frame assembly, a vertical shaft, and a half-coupling. A sorting rotor is fixedly connected to the vertical shaft. The sorting rotor is cage-shaped and includes a rotor frame. A set of arc-shaped moving blades are evenly distributed around the rotor frame, along the rotation direction of the sorting rotor and at an angle of 12° to 47° to the center line of the sorting rotor. A material spreading disc is fixedly connected to the top of the sorting rotor. The material spreading disc includes a second ring located at the top. A set of annular sealing blades is fixedly connected to the outer side of the second ring. The second ring and the sealing blades... The upper end of the disc is inserted into the sealing groove at the bottom of the air outlet housing. A set of spreading columns and a set of spreading plates are fixedly connected to the top of the outer periphery of the spreading disc. The spreading columns and spreading plates are perpendicular to the spreading disc and evenly distributed. A layered impact guiding assembly is fixedly connected to the top of the sorting housing. The layered impact guiding assembly has a ring-shaped structure, which includes a first ring, an impact guiding cone, and a connecting plate. The first ring is fixedly connected to the inside of the upper layer of the sorting housing. The impact guiding cone forms a 60° angle with the horizontal plane and is fixedly connected to the first ring through the connecting plate. A fixing ring is provided at the bottom of the layered impact guiding assembly, which includes an outer ring fixedly connected to the inside of the upper layer of the sorting housing. The outer ring is fixedly connected to the inner ring by a set of vertical stiffeners. The inner ring is fixedly connected to the inner ring plate-shaped combined air guide vanes, which include vortex vanes and plate-shaped air guide vanes. The upper part of the inner ring is fixedly connected to the fixed ring, and the lower part is fixedly connected to the inner collection hopper. The lower layer of the sorting shell is provided with an outer ring S-shaped blade, which includes a blade angle adjustment mechanism and an S-shaped air guide vane. The upper part of the outer ring is connected to the lower layer of the sorting shell by a pin shaft, and the lower part is connected to the outer collection hopper by a pin shaft. The sorting rotor is located inside the inner ring plate-shaped combined air guide vanes. The bottom of the outer collection hopper and the inner collection hopper are provided with a discharge port and a three-stage air inlet.

[0013] A dynamic fluidization system is provided on one side of the layered impact guiding component, which includes a high-pressure axial flow fan, connecting pipes and a set of air nozzles. The air nozzles are located at the bottom of the air outlet shell and close to the layered impact guiding component. The air nozzles are aligned with the layered fluidization dispersion chamber and are evenly distributed. The primary air inlet, secondary air inlet and tertiary air inlet constitute the air intake system of the low-resistance high-efficiency classifier.

[0014] Preferably, the mixing and feeding device includes an inverted conical shell and a cylindrical shell fixedly connected to the lower end of the inverted conical shell. A feeding pipe is fixedly connected to the side wall of the inverted conical shell, and the feeding pipe is inclined.

[0015] Preferably, the grinding mechanism further includes a drive device for driving the grinding disc assembly to rotate, and a set of grinding rollers located above the grinding disc assembly and cooperating with the top of the grinding disc assembly. One end of the grinding roller is fixedly connected to a roller sleeve, and the other end of the grinding roller is fixedly connected to a pressurizing device. The bottom plate of the outer shell is fixedly connected to a discharge pipe and an air inlet. An air guide ring is fixedly connected inside the outer shell. An annular air duct is formed between the upper outer periphery of the grinding disc assembly and the air guide ring. The grinding disc assembly includes a disc base. The bottom of the disc base is fixedly connected to the output end of the drive device. A set of liners is fixedly connected to the upper surface of the disc base. A spherical groove grinding track is formed between the liners. A baffle ring is fixedly connected to the upper surface of the outer edge of the disc base. A scraper frame is fixedly connected to the bottom of the lower surface of the upper part of the disc base. A set of scraper blades is fixedly connected to the scraper frame. The scraper blades are distributed in the lower outer periphery of the disc base, located in the annular space between the grinding disc assembly and the outer shell. A mixer is provided at the center of the top of the grinding disc assembly.

[0016] Preferably, the grinding rollers are distributed at equal angles around the center of the grinding disc assembly, with the axial centerline of each grinding roller having an inclination angle of less than or equal to 12° with the horizontal plane. Each grinding roller is arranged at equal angles and distances to each other on the horizontal plane. The grinding surface of the roller sleeve is a conical drum-shaped spherical surface with an annular groove in the middle of the spherical surface. Its outer surface is made of wear-resistant material. The total projected area of ​​the grinding rollers on the grinding disc assembly is 45% to 60% of the grinding track area. The wind speed V of the annular channel between the upper outer periphery of the grinding disc and the air guide ring inside the outer shell is 6 m / s to 8 m / s.

[0017] Preferably, the material distribution bin is located at the top of the low-resistance high-efficiency classifier and serves as the discharge port of the external circulation elevator, used to evenly distribute the ground material into the low-resistance high-efficiency classifier.

[0018] Preferably, the low-resistance high-efficiency classifier is fixedly connected to the outer shell of the grinding mechanism. The stratified fluidized dispersion chamber is located on the upper layer of the classification shell, and the lower layer of the classification shell is provided with a classification zone, namely a strong cyclone classification zone and a forced vortex classification zone. The stratified fluidized dispersion chamber is surrounded by a feeding disc and a stratified impact guiding component. The strong cyclone classification zone is annular, surrounded by an outer ring of annular S-shaped guide vanes and an inner ring of plate-shaped combined guide vanes, forming a channel for separating coarse and fine particles and guiding fine particles. The forced vortex classification zone is annular, surrounded by an inner ring of plate-shaped combined guide vanes and a classification rotor, forming a channel for separating small particles and powdery materials and guiding the selected finished product. The outer ring of annular S-shaped vanes is located outside the strong cyclone classification zone, and the inner ring of plate-shaped combined guide vanes is located inside the strong cyclone classification zone.

[0019] Preferably, the outer collecting hopper is located in the lower part of the strong vortex classification zone to collect large particles after coarse separation, and the inner collecting hopper is located in the lower part of the forced vortex classification zone to collect small particles that fall vertically after separation. The inner collecting hopper is fixedly connected to the outer collecting hopper, and the outer collecting hopper is located inside the lower shell and fixedly connected to the lower air ring.

[0020] Preferably, the adjustable range of the nozzle wind speed V1 in the strong vortex classification zone is 15 m / s to 25 m / s, the inlet wind speed V2 at the inner ring plate-shaped combined air guide blades is 4 m / s to 5 m / s, the design range of the nozzle wind speed V3 in the forced vortex classification zone is 9 m / s to 12 m / s, the design range of the ratio of the sorting rotor diameter to its height D / H is 1.5 to 1.6, the design range of the inlet wind speed V4 between the sorting rotor blades is 2.7 m / s to 3.5 m / s, and the adjustable range of the rotational linear velocity V5 of the outer diameter of the sorting rotor is 22 m / s to 27 m / s.

[0021] A method for using a low-energy external circulation vertical roller mill for cement, the steps of which are as follows:

[0022] S1. Mixing and feeding: The newly fed cement raw materials and the recycled material from the low-resistance high-efficiency separator are mixed in the mixing and feeding device and then fed into the center of the grinding disc assembly of the grinding mechanism.

[0023] S2. Coarse crushing and grinding: By starting the drive device and pressurizing device of the grinding mechanism, the grinding disc assembly is rotated and pressure is applied to the grinding roller. Under the centrifugal force of the grinding disc assembly, the material enters the grinding track to form a material layer, so that a coarse crushing chamber and a grinding chamber with a reasonable distribution of multi-dimensional force field are formed between the grinding roller sleeve and the grinding disc assembly liner. Under the crushing of the grinding roller, the material is crushed in sequence through the coarse crushing chamber and the grinding chamber.

[0024] S3. Dispersion and Lifting: Most of the ground material is dispersed by the rotating scraper and discharged. It is then mechanically lifted by the external circulation elevator, and after being evenly distributed by the distribution bin, it is fed into the low-resistance high-efficiency classifier.

[0025] S4. Pre-selection and fine selection: The material entering the low-resistance high-efficiency air classifier is fluidized and initially dispersed in the stratified fluidized dispersion chamber, and then enters the strong vortex classification zone. Coarse particles are separated under the action of centrifugal force and velocity gradient shear and fall into the external collection hopper. Fine particles and powdery materials enter the forced vortex classification zone, where they are separated under the combined action of centrifugal force generated by the sorting rotor and airflow suction. Powdery materials with qualified fineness are discharged from the air outlet with the airflow and collected by the dust collector. Fine particles with unqualified fineness are separated and fall into the internal collection hopper. Coarse particles and fine particles are returned to the mixing and feeding device as recycled materials and re-enter the grinding mechanism for a new round of grinding.

[0026] The beneficial effects of this invention are:

[0027] (1) The low-energy external circulation cement vertical roller mill and its usage method described in this invention separate the grinding and classification functions of the traditional internal circulation cement vertical mill through the external circulation elevator and the low-resistance high-efficiency classifier. After the material is ground, more than 95% of the material is discharged to the outside of the mill for external circulation. It is mechanically lifted into the low-resistance high-efficiency classifier for horizontal airflow gradient classification of coarse and fine particles. The classified finished product enters the dust collector. The material with unqualified fineness is returned to the vertical mill for re-grinding. It is mechanically lifted into the classifier to reduce the power consumption of the circulating fan. The airflow is horizontal and tangential during the classification, which greatly reduces the energy consumption of gas-carrying material transportation. Only a small amount of ventilation is provided in the vertical mill to stabilize the material layer and collect dust. The pressure head and air volume of the circulating fan of the system are greatly reduced, which truly achieves the effect of energy saving and consumption reduction.

[0028] (2) The low-energy external circulation cement vertical roller mill and its usage method described in this invention optimize the relative position of the roller and the disk under force by forming a grinding mechanism through the spherical groove liner plate installed on the grinding disc and the conical drum spherical roller sleeve installed on the grinding roller, and reasonably establish the energy distribution of the material layer crushing. After the material on the grinding disc is ground, it is thrown out under the action of the centrifugal force generated by the rotation of the grinding disc. Therefore, the thickness of the material layer on the disc is thinner than that of the traditional internal circulation vertical mill, which greatly improves the grinding efficiency, reduces the grinding energy consumption, reduces the circulating load, stabilizes the material layer, reduces the mill vibration, and improves the equipment stability.

[0029] (3) The low-energy external circulation cement vertical roller mill and its usage method described in this invention adopt the form of top feeding, layered fluidized spreading, tangential horizontal air intake, and horizontal airflow gradient classification of coarse and fine particles for classification. This solves the problems of large mill vibration, low roller pressure, low output, and high power consumption. Through zoned gradient classification, the pressure head and air volume of the circulating fan required for powder classification are greatly reduced, effectively reducing the resistance of the powder classifier and achieving high solid-to-gas ratio, low resistance, and high-efficiency powder classification.

[0030] (4) The low-energy external circulation vertical roller mill for cement and its usage method described in this invention replaces the pneumatic conveying inside the mill with mechanical lifting outside the mill, which greatly reduces the pressure head and air volume of the circulating fan in the system, avoids the high-speed airflow carrying materials to scour the surface of various parts inside the mill, reduces wear, and extends the service life of the grinding body and various components.

[0031] (5) The low-energy external circulation cement vertical roller mill and its usage method described in this invention, through a fully enclosed structure and micro negative pressure operation, produces dust-free production processes, realizes intelligent production equipment, is conducive to large-scale production, and reduces production energy consumption. Attached Figure Description

[0032] The present invention will be further described below with reference to the accompanying drawings and embodiments.

[0033] Figure 1 This is a schematic diagram of the operation of the external circulation cement vertical roller mill provided by the present invention;

[0034] Figure 2 A top view of the grinding mechanism of the external circulation cement vertical roller mill provided by the present invention;

[0035] Figure 3 A schematic diagram of the structure of the low-resistance, high-efficiency air classifier for external circulation cement vertical roller mill provided by the present invention;

[0036] Figure 4 HH cross-sectional view of the low-resistance high-efficiency air classifier for external circulation cement vertical roller mill provided by the present invention;

[0037] Figure 5 for Figure 4 Enlarged view at point 4-1;

[0038] Figure 6 The working process diagram of the external circulation cement vertical roller mill grinding system provided by the present invention;

[0039] Figure 7 for Figure 1 Enlarged view of point 1-1;

[0040] Figure 8 for Figure 3 Enlarged view at point 3-1;

[0041] Figure 9 for Figure 3 Enlarged view of section 3-2;

[0042] Figure 10 for Figure 5 Enlarged view at point 5-1.

[0043] In the diagram: 100, mixing and feeding device; 110, feeding pipe; 120, inverted conical shell; 130, cylindrical shell;

[0044] 200. Grinding mechanism; 201. Drive unit; 202. Pressurizing device; 210. Grinding disc assembly; 211. Disc base; 212. Liner; 213. Material retaining ring; 214. Scraper frame; 215. Scraper blade; 216. Mixer; 220. Grinding roller; 221. Roller sleeve; 230. Outer shell; 231. Discharge pipe; 232. Air inlet; 233. Air guide ring;

[0045] 300. External circulation elevator; 310. Material distribution bin;

[0046] 400. Low-resistance, high-efficiency air classifier; 410. Sorting shell; 411. Primary air inlet; 412. Layered impact guide assembly; 412a. First ring; 412b. Impact guide cone; 412c. Connecting plate; 413. Fixing ring; 413a. Outer ring; 413b. Vertical rib; 413c. Inner ring; 414. Outer ring S-shaped blade; 414a. Blade angle adjustment mechanism; 414b. S-shaped guide vane; 414c. Pin; 415. Inner ring plate-shaped combined guide vane; 415a. Vortex blade; 415b. Plate-shaped guide vane; 416. External hopper; 417. Internal hopper; 418. Discharge port; 419. Third... 420. Air inlet; 421. Air outlet; 422. Feeding port; 423. Transmission device; 423a. Variable frequency motor; 423b. Reducer; 423c. Shaft frame assembly; 423d. Vertical shaft; 423e. Half coupling; 424. Spreading disc; 424a. Second ring; 424b. Sealing blade; 424c. Spreading column; 424d. Spreading plate; 425. Dynamic fluidization system; 425a. High-pressure axial flow fan; 425b. Connecting pipe; 425c. Air nozzle; 426. Sorting rotor; 426a. Rotor frame; 426b. Arc-shaped moving blade; 430. Lower housing; 431. Lower air ring; 432. Secondary air inlet;

[0047] 500. Dust collector; 600. Circulating fan;

[0048] PS, coarse crushing chamber; NM, grinding chamber;

[0049] FS, stratified fluidized dispersion chamber; XL, strong vortex classification zone; WL, forced eddy classification zone;

[0050] V, wind speed in the annular channel between the upper outer periphery of the grinding disc and the air guide ring; V1, wind speed at each nozzle in the strong vortex classification zone; V2, inlet wind speed at the inner ring plate-shaped combined air guide blades; V3, wind speed at each nozzle in the forced vortex classification zone; V4, inlet wind speed between the sorting rotor blades; V5, rotational linear velocity of the outer diameter of the sorting rotor.

[0051] A. Coarse granular materials; B. Fine granular materials; C. Powdered materials. Detailed Implementation

[0052] To make the technical means, creative features, objectives and effects of this invention easier to understand, the invention will be further described below in conjunction with specific embodiments.

[0053] Example 1: As Figures 1-10As shown, the present invention discloses a low-energy external circulation vertical roller mill for cement and its usage method, comprising a mixing and feeding device 100 disposed inside the mill, and a grinding mechanism 200 disposed at the bottom of the mixing and feeding device 100. The grinding mechanism 200 includes a housing 230 and a grinding disc assembly 210 disposed inside the housing 230. An external circulation elevator 300 fixed to the foundation is disposed outside the grinding mechanism 200. The inlet of the external circulation elevator 300 is connected to the outlet of the grinding mechanism 200. The external circulation elevator 300 discharges the ground material in the grinding mechanism 200 to the outside of the grinding mechanism 200 for external circulation, and feeds it into a low-resistance high-efficiency classifier 400 located above the grinding mechanism 200 by mechanical lifting. The mixing and feeding device 100 is configured to receive and feed the material. The newly fed raw materials are mixed with the recycled material from the low-resistance high-efficiency classifier 400, and the mixture is fed into the center of the grinding disc assembly 210 of the grinding mechanism 200. The low-resistance high-efficiency classifier 400 is fixedly connected to the outer shell 230 of the grinding mechanism 200. A set of feeding ports 422 at the top of the classifier is connected to the discharge port of a set of material bins 310 of the external circulation elevator 300. An air outlet 421 on one side of the top of the classifier is connected to the dust collector 500. The prepared material is fluidized and dispersed in the stratified fluidized dispersion chamber FS located in the middle of the low-resistance high-efficiency classifier 400. The shear force of the horizontal velocity gradient is used to break up the particle agglomerates. The material enters the strong swirling classification zone XL and the forced vortex classification zone WL. In the swirling and vortex fields, the material is centrifugally settled and classified according to particle size, so as to achieve the classification of coarse particles A and fine particles B.

[0054] In this embodiment, the crushed cement raw material enters the mill through the feeding pipe 110, and is mixed with the recycled material returned from the low-resistance high-efficiency classifier 400 after grinding, coarse selection, and fine selection. The mixture is then fed into the mixing and feeding device 100, where it is pre-mixed evenly. The material is then fed into the center of the grinding disc assembly 210 of the grinding mechanism 200. The coarse and fine particles fall into the center of the grinding disc assembly 210. Under the centrifugal force of the rotating grinding disc assembly 210, the material is carried into a special crushing zone formed by the spherical grooved liner 212 and the conical drum-shaped spherical roller sleeve 221. The material first enters the relatively low-pressure coarse crushing chamber PS, undergoes pre-crushing and compaction to form a flat material bed, and then enters the high-pressure grinding chamber NM. Under strong extrusion and shearing forces, it is effectively crushed. Most of the crushed material is thrown away from the grinding disc assembly 210 in the form of a cake and falls into the annular area at the bottom of the mill. The scraper 215, which rotates with the grinding disc, mechanically breaks it down into loose particles. The particles then fall into the external circulation elevator 300 and are mechanically and vertically lifted to the top distribution bin 310. The material then enters the low-resistance high-efficiency classifier 400. The material is dispersed by the spreading disc 424 and, with the assistance of the dynamic fluidization system 425, achieves full single-particle dispersion in the stratified fluidized dispersion chamber FS. The dispersed material enters the strong vortex classification zone XL, where the tangentially entering high-speed horizontal airflow forms a rotating flow field. The huge velocity gradient between the high speed of the outer ring and the low speed of the inner ring generates strong horizontal shear force, which performs secondary separation of the particle agglomerates. Coarse particles B are thrown out under the action of centrifugal force, and after impacting the outer ring annular S-shaped blades 414, they fall at a loss and are collected as coarse return material. The finer material enters the forced vortex classification zone WL. In the vortex field formed by the high-speed rotating cage-shaped sorting rotor 426, the particles are subjected to the combined force of centrifugal force and airflow suction force. By precisely adjusting the rotation speed of the sorting rotor 426, the "cutting particle size" is controlled. Particles that do not meet the fineness requirements are thrown out due to the large centrifugal force and collected as fine return material. The qualified ultrafine powder is drawn through the rotor by the airflow and becomes the finished product. The horizontal airflow gradient classification of coarse and fine particles can significantly reduce the finished product content in the recycled material, improve the powder selection efficiency, reduce the recycling load rate, and at the same time help stabilize the material layer, reduce mill vibration, improve grinding efficiency, and reduce system energy consumption.

[0055] Specifically, such as Figure 1 , Figure 2 and Figure 7As shown, the mixing and feeding device 100 includes an inverted conical shell 120 and a cylindrical shell 130 fixedly connected to the lower end of the inverted conical shell 120. A feeding pipe 110 is fixedly connected to the side wall of the inverted conical shell 120, and the feeding pipe 110 is inclined. The grinding mechanism 200 also includes a driving device 201 for driving the grinding disc assembly 210 to rotate, and a set of grinding rollers 220 located above the grinding disc assembly 210 and cooperating with the top of the grinding disc assembly 210. One end of the grinding roller 220 is fixedly connected to a roller sleeve 221, and the other end of the grinding roller 220 is fixedly connected to a pressurizing device 202. The bottom plate of the outer shell 230 is fixedly connected to a discharge pipe 231 and an air inlet 232. An air guide ring 233 is fixedly connected inside the outer shell 230. An annular air duct is formed between the upper outer periphery of the grinding disc assembly 210 and the air guide ring 233. The grinding disc assembly 210 includes a disc base 211. The bottom of the disc base 211 is fixedly connected to the output end of the drive device 201, and the upper surface of the disc base 211 is fixedly connected to... A set of liner plates 212 are connected, forming a spherical groove grinding track between the liner plates 212. A baffle ring 213 is fixedly connected to the upper surface of the outer edge of the disc base 211. A scraper frame 214 is fixedly connected to the bottom of the lower surface of the upper part of the disc base 211. A set of scraper plates 215 are fixedly connected to the scraper frame 214. The scraper plates 215 are distributed in the lower outer periphery of the disc base 211, located in the annular space between the grinding disc assembly 210 and the housing. The grinding disc assembly 210 is located at the top center. There is a mixer 216; grinding rollers 220 are distributed at equal angles around the center of the grinding disc assembly 210, and the axial center line of each grinding roller 220 is inclined at an angle less than or equal to 12° with the horizontal plane. Each grinding roller 220 is arranged at equal angles and distances to each other on the horizontal plane. The grinding surface of the roller sleeve 221 is a conical drum-shaped spherical surface, and an annular groove is provided in the middle of the spherical surface. Its outer surface is made of wear-resistant material. The total projected area of ​​the grinding rollers 220 on the grinding disc assembly 210 is 45% to 60% of the grinding track area.

[0056] In this embodiment, the drive device 201 drives the grinding disc assembly 210 to rotate and can be frequency-controlled to provide power to the grinding mechanism 200. The pressurizing device 202 provides controllable hydraulic grinding pressure to the grinding roller 220. The crushed cement raw material enters the mill mixing and feeding device 100 through the feeding pipe 110. The recycled material (including coarse particles A and fine particles B) after grinding, coarse selection and fine selection enters the mill mixing and feeding device 100 through the discharge port 418 at the bottom of the external collection hopper 416 and the internal collection hopper 417. 0. The mixing and feeding device 100 feeds the newly fed material and the recycled material into the center of the grinding disc assembly 210. The surface of the annular groove on the top of the grinding disc assembly 210 is made with wear-resistant material. The material throughput is controlled by adjusting the height between the discharge port of the mixing and feeding device 100 and the grinding disc assembly 210. At the same time, the material level in the mixing and feeding device 100 is controlled to lock the air. With the help of the mixer 216 on the grinding disc, the block material and the recycled material are evenly mixed to form a particle group with a combination of coarse and fine particles, which is continuously and stably fed into the grinding mechanism 200 for crushing.

[0057] Specifically, under the centrifugal force generated by the rotating grinding disc assembly 210, the material moves towards the edge of the grinding disc assembly 210, enters the grinding track, forms a material layer, and drives multiple grinding rollers 220 to rotate. This causes the roller sleeves 221 of the grinding rollers 220 and the grinding disc liner 212 to form a coarse crushing chamber PS and a grinding chamber NM with a reasonable distribution of multi-dimensional force fields. The grinding disc and grinding rollers 220 perform high and low pressure zone crushing of the fed cement raw material particles. The material in the coarse crushing chamber PS experiences low pressure, mainly through impact and extrusion, pre-compressing the material and preparing a smooth and compacted material layer for the grinding chamber NM. The material is subjected to high and concentrated pressure. Under the action of multi-dimensional force fields such as extrusion, shearing, and friction, the granular cement raw materials are extruded and ground into fine powder by utilizing the velocity difference generated when the particle group moves in layers within the material layer. The protruding edges and corners on the fine particles are ground off. There is a structure with an internal air exhaust function between the coarse crushing chamber PS and the grinding chamber NM, forming an annular material dam to prevent large particles from entering the grinding chamber NM and avoid the escape of large particles. The grinding mechanism 200 with coarse crushing and grinding zones is conducive to forming a stable material layer with uniform thickness, reducing vibration, improving grinding efficiency, and optimizing cement particle size distribution and particle morphology.

[0058] Specifically, the ground material continues to move towards the edge of the grinding disc assembly 210 under the action of centrifugal force. There is gas flowing obliquely upward in the discharge annular channel. A small part of the material will be blown back into the grinding disc assembly 210. Among them, the finer particles are carried into the low-resistance high-efficiency classifier 400 by the airflow. Most of the material enters the shell annular groove downward. Under the centrifugal impact of the rotating scraper 215, the large clumps of material are broken up and discharged from the discharge pipe 231 into the external circulation elevator 300 for lifting and feeding into the feed inlet of the distribution bin 310. Multiple branch pipes of the distribution bin 310 are connected to the feed port 422 at the top of the low-resistance high-efficiency classifier 400. The number of feed ports 422 is set to 4, 6 or 8. After the material is evenly distributed from the distribution bin 310, it enters the feed port 422 of the low-resistance high-efficiency classifier 400 and is classified and separated into coarse and fine particles by horizontal airflow gradient classification in the low-resistance high-efficiency classifier 400.

[0059] Specifically, such as Figures 3-5 as well as Figures 8-10As shown, the distribution bin 310 is located at the top of the low-resistance high-efficiency classifier 400 and serves as the discharge port of the external circulation elevator 300. It is used to evenly distribute the ground material into the low-resistance high-efficiency classifier 400. The low-resistance high-efficiency classifier 400 also includes a sorting shell 410 located in the middle of the low-resistance high-efficiency classifier 400. The lower periphery of the sorting shell 410 is provided with a primary air inlet 411, which is tangentially arranged along the tangent of the shell and is arranged in a group and evenly distributed. The top of the sorting shell 410 is fixedly connected to the air outlet shell 420 by flanges and bolts. The lower shell 430 is provided below the sorting shell 410. The lower shell 430 includes a lower air ring 431 located at the top. The sorting shell 410 has a double-layer cylindrical structure. An air outlet is fixedly connected to one side of the top of the air outlet shell 420. The air outlet 421 is inclined at a 30° angle to the horizontal plane. A set of evenly distributed feeding ports 422 are fixedly connected to the bottom plate of the air outlet housing 420. The lower housing 430 is fixedly connected to the lower part of the sorting housing 410 and the outer shell 230 of the grinding mechanism 200, and together with the sorting housing 410, they form a secondary air inlet 432. A transmission device 423 is fixedly connected to the top of the air outlet housing 420. The transmission device 423 consists of a variable frequency motor 423a, a reducer 423b, a shaft frame assembly 423c, a vertical shaft 423d, and a half coupling 423e. A sorting rotor 426 is fixedly connected to the vertical shaft 423d. The sorting rotor 426 is cage-shaped and includes a rotor frame 426a. A set of evenly distributed feeding ports along the periphery of the rotor frame 426a are provided for the sorting rotor 426. An arc-shaped moving blade 426b rotates at an angle of 12° to 47° to the centerline of the sorting rotor 426. A material spreading disc 424 is fixedly connected to the top of the sorting rotor 426. The material spreading disc 424 includes a second ring 424a located at the top. A set of annular sealing blades 424b are fixedly connected to the outer side of the second ring 424a. The upper ends of the second ring 424a and the sealing blades 424b are inserted into the sealing groove at the bottom of the air outlet housing 420. A set of material spreading columns 424c and a set of material spreading plates 424d are fixedly connected to the top of the outer periphery of the material spreading disc 424. The material spreading columns 424c and the material spreading plates 424d are both perpendicular to the material spreading disc 424 and are evenly distributed. A layered impact guiding assembly 412 is fixedly connected to the top of the sorting housing 410. Component 412 has a ring-shaped structure, including a first ring 412a, an impact guide cone 412b, and a connecting plate 412c. The first ring 412a is fixedly connected to the inner upper layer of the sorting housing 410. The impact guide cone 412b forms a 60° angle with the horizontal plane and is fixedly connected to the first ring 412a via the connecting plate 412c. A fixing ring 413 is provided at the bottom of the layered impact guide assembly 412, which includes an outer ring 413a fixedly connected to the inner upper layer of the sorting housing 410. The outer ring 413a is fixedly connected to an inner ring 413c via a set of vertical stiffeners 413b. The inner ring 413c is fixedly connected to an inner ring plate-shaped combined air guide vane 415, which includes a vortex vane 415a and a plate-shaped air guide vane 415b.Its upper part is fixedly connected to the fixed ring 413, and its lower part is fixedly connected to the internal collection hopper 417. The lower layer of the sorting shell 410 is provided with an outer ring S-shaped blade 414, which includes a blade angle adjustment mechanism 414a and an S-shaped guide blade 414b. Its upper part is connected to the lower layer of the sorting shell 410 by a pin 414c, and its lower part is connected to the external collection hopper 416 by the pin 414c. The sorting rotor 426 is located inside the inner ring plate-shaped combined guide blade 415. The bottom of the external collection hopper 416 and the internal collection hopper 417 are provided with a discharge port 418 and a tertiary air inlet 419.

[0060] In this embodiment, the material entering the low-resistance high-efficiency classifier 400 from the distribution bin 310 is fully fluidized by the high-speed rotating spreading disc 424, the dynamic fluidization system 425, and the layered impact guiding component 412 before entering the strong cyclone classification zone XL, forming a uniformly thick material curtain. The fluidized mixture (coarse particles A + fine particles B + powdery material C) enters the strong cyclone classification zone XL for pre-classification and dispersion. In this classification zone, the nozzle wind speed V1 (15m / s to 25m / s) at the outer ring annular S-shaped blades 414 and the inner ring plate-shaped combined guide vanes 41 The inlet wind speed V2 at 5a (4m / s to 5m / s) differs significantly, resulting in a large velocity gradient. The high-speed rotating airflow in the annular region causes the coarse particles A in the material to gain significant kinetic energy. They then impact the inner arc surface of the S-shaped guide vane 414b and lose velocity. Under the action of gravity, the coarse particles A are separated. The tangential shear force formed by the velocity gradient peels off the sticky particle clusters layer by layer, thus breaking them up and preparing them for further separation in the forced vortex classification zone WL. The separated coarse particles A are then ground by their own gravity and returned to the grinding mechanism 200 through the external collection hopper 416 for further grinding.

[0061] Specifically, a dynamic fluidization system 425 is provided on one side of the layered impact guiding assembly 412, which includes a high-pressure axial flow fan 425a, a connecting pipe 425b, and a set of air nozzles 425c. The air nozzles 425c are located at the bottom of the air outlet housing 420 and close to the layered impact guiding assembly 412. The air nozzles 425c are aligned with the layered fluidization dispersion chamber FS and are evenly distributed. The primary air inlet 411, the secondary air inlet 432, and the tertiary air inlet 419 constitute the air inlet system of the low-resistance high-efficiency classifier 400. The low-resistance high-efficiency classifier 400 and the grinding mechanism 200 housing 2 30. Fixed connection. The stratified fluidized dispersion chamber FS is located on the upper layer of the sorting shell 410. The lower layer of the sorting shell 410 is equipped with a classification zone, namely the strong cyclone classification zone XL and the forced vortex classification zone WL. The stratified fluidized dispersion chamber FS is enclosed by the feeding disc 424 and the stratified impact guiding assembly 412. The strong cyclone classification zone XL is annular, enclosed by the outer ring annular S-shaped blades 414 and the inner ring plate-shaped combined guide vanes 415, forming a channel for separating coarse and fine particles and guiding fine particles B. The forced vortex classification zone WL is annular, enclosed by the inner ring plate-shaped combined guide vanes 414 and 415. The separator 15 and the sorting rotor 426 enclose each other, forming a channel for separating small particles from powdery materials C and guiding the refined finished product. The outer ring S-shaped blades 414 are located outside the strong cyclone classification zone XL, and the inner ring plate-shaped combined guide vanes 415 are located inside the strong cyclone classification zone XL. The outer collecting hopper 416 is located at the lower part of the strong cyclone classification zone XL to collect large particles after coarse separation, and the inner collecting hopper 417 is located at the lower part of the forced vortex classification zone WL to collect small particles that fall vertically after separation. The inner collecting hopper 417 is fixedly connected to the outer collecting hopper 416. The hopper 416 is located inside the lower shell 430 and is fixedly connected to the lower air ring 431; the wind speed V in the annular channel between the upper outer periphery of the grinding disc and the air guide ring 233 inside the outer shell 230 is 6 m / s to 8 m / s; the adjustable range of the wind speed V1 at each nozzle in the strong vortex classification zone is 15 m / s to 25 m / s; the inlet wind speed V2 at the inner ring plate-shaped combined air guide blade 415 is 4 m / s to 5 m / s; the design range of the wind speed V3 at each nozzle in the forced vortex classification zone is 9 m / s to 12 m / s; the design range of the diameter-to-height ratio D / H of the sorting rotor 426 is 1.5 to 1.6; the design range of the inlet wind speed V4 between the blades of the sorting rotor 426 is 2.7 m / s to 3.5 m / s; and the adjustable range of the rotational linear velocity V5 of the outer diameter of the sorting rotor 426 is 22 m / s to 27 m / s.

[0062] In this embodiment, fine particulate material B and powdered material C, under the suction force of the wind, continue to enter the forced vortex classification zone WL for further sorting. In this classification zone, the wind speed V3 (9m / s to 12m / s) at each nozzle of the inner ring plate-shaped combined guide vane 415 and the inlet wind speed V4 (2.7m / s to 3.5m / s) between the blades of the sorting rotor 426 differ significantly, resulting in a large velocity gradient. The tangential shear force formed by the velocity gradient further peels off the powdered material C adhering to the surface of the fine particulate material B. In the forced vortex classification zone WL, the classification of fine particulate material B and powdered material C is strictly based on the centrifugal force generated by the rotation of the sorting rotor 426 and the suction force of the wind. Larger particles receive greater centrifugal force, and the fine particulate material B that does not meet the fineness requirements is thrown out and enters the rotating airflow in the inner ring plate. The particles stall in the small vortex field generated inside the combined guide vane 415 and enter the mixing and feeding device 100 through the internal collection hopper 417 under their own gravity. The particles with small mass receive less centrifugal force, and the fine powder material C (cement finished product) with qualified fineness enters the dust collector 500 for collection as finished product through the suction force of the airflow by the high-speed rotating sorting rotor 426. By adjusting the angle of the S-shaped guide vane 414b, the speed of the sorting rotor 426 and the air volume of the circulating fan 600, the tangential airflow velocity in the strong swirling classification zone XL and the forced vortex classification zone WL is maximized, and the uniformity of airflow distribution in the strong swirling classification zone XL and the forced vortex classification zone WL is improved. Therefore, the horizontal tangential shear force formed by the wind speed gradient in the two classification zones is enhanced, and the ability to break up particle agglomerates is improved under the condition of high solid-gas ratio. The air passage area of ​​the sorting rotor 426 is increased and the system resistance is reduced.

[0063] Specifically, the vortex grading zone WL is annular, enclosed by an inner ring of plate-shaped combined guide vanes 415 and a sorting rotor 426, forming a channel for separating small particles from powdery materials C and guiding the selected finished product. The fineness of the finished product is adjusted by controlling the rotation speed of the sorting rotor 426 and the powder-selecting air volume. The internal collecting hopper 417 collects the vertically falling small particles after separation. Both the internal collecting hopper 417 and the external collecting hopper 416 have wear-resistant treatment at the material flow points. The number of primary air inlets 411 is set to 4 and 6 respectively. There are one or eight evenly distributed secondary air inlets 432, which are enclosed by the lower shell 430 and the external collection hopper 416 to form a ventilation channel inside the mill. The ventilation volume inside the mill is controlled at about 15% of the system air volume. The discharge port 418 is located at the lower part of the external collection hopper 416 and the internal collection hopper 417 and is connected to the mixing and feeding device 100. The tertiary air inlet 419 is located at the lower part of the external collection hopper 416 and the internal collection hopper 417. Air enters from the feeding pipe 110. There is no need to install an air lock device on the upper part of the feeding pipe 110.

[0064] Example 2: Based on Example 1, the present invention achieves good results, as shown in Table 1:

[0065] Table 1 compares the various aspects of the preparation of P.O42.5 cement using the present invention and the traditional internal circulation cement vertical mill.

[0066] Grinding mechanism type Spherical grooved liner + conical drum-shaped spherical roller sleeve Flat conical roller / bowl roller Air classifier configuration and layout <![CDATA[High solid-gas ratio and low-resistance high-efficiency classifier, with classification concentration greater than 800 g / m 3 ; Built-in type, top feeding, side air intake, high classification efficiency]]> <![CDATA[High-efficiency dynamic powder separator, powder selection concentration is about 400 g / m 3 ; Built-in type, with feed inside the mill, air inlet inside the mill, and low powder selection efficiency]]> Material conveying methods Mechanical lifting using an external circulation hoist Mainly through internal pneumatic boost Built-in nozzle annular wind speed V 6~8m / s 45~60m / s System air resistance The built-in nozzle ring resistance consumption is 100~200Pa, and the air classifier resistance consumption is 2500~3000Pa. The built-in nozzle ring has a resistance consumption of 3000~4500Pa, and the built-in high-efficiency dynamic air classifier has a resistance consumption of 2000~2500Pa. System control core parameters System material circulation volume (reflected by changes in the current of the discharge elevator) Internal pressure difference Product fineness adjustment The circulating fan has low overall pressure, small air volume, and easily adjustable air fineness. The circulating fan has high total pressure, large air volume, and difficulty in adjusting the fineness. Impact of grinding roller wear With no air sweeping, roller sleeve wear is minimal, resulting in high output and minimal impact on product fineness. High wear, due to uneven wear causing a significant reduction in performance and resulting in coarser product particle size. Main motor power consumption The material is completely discharged after being crushed 3 to 4 times inside the mill. The material flow rate is fast, the grinding pressure is high, the material layer is moderate, the crushing efficiency is high, and the power consumption is low, about 15 to 17 (kWh / t). After the material is crushed inside the mill, most of it circulates internally, resulting in a long residence time, a thick material layer, low crushing efficiency, and high power consumption, approximately 18~20 (kWh / t). Power consumption of circulating fan 2~3 (kWh / t) 6~8 (kWh / t) Power consumption of external circulation elevator The system's material circulation rate is 350%–400% of the feed rate, and the circulating bucket elevator capacity is large, approximately 0.7 (kWh / t). The discharge rate of some materials is 20% to 30% of the feed rate, and the circulating bucket elevator capacity is small, about 0.2 (kWh / t). System power consumption (kWh / t) 20~23 (kWh / t) 27~30 (kWh / t) Repair costs The grinding rollers and liners have a lifespan of 10,000 to 15,000 hours, with few mechanical failures and low maintenance costs. The grinding roller and liner surfaces must be overlaid with weld every 4,000 to 8,000 hours, resulting in high maintenance costs and concerns about the weld overlay peeling off. System complexity Simple Simple

[0067] Working Principle: For cold grinding of cement raw materials with a comprehensive moisture content of less than 2.5%, the grinding device adopts a grinding mechanism 200 formed by a spherical grooved liner 212 and a conical drum-shaped spherical roller sleeve 221, based on the principle of material layer crushing under the action of a multi-dimensional force field. This optimizes the relative position of the rollers and discs, rationally establishes the energy distribution of material layer crushing, improves grinding efficiency, and reduces circulating load. Based on the density and particle size of the ground material, the sorting device adopts a high solid-to-gas ratio, low-resistance, high-efficiency air classifier 400 with top feeding, layered fluidized feeding, tangential horizontal air intake, and multi-stage gradient classification of coarse and fine particles. It utilizes the multi-force field action of swirling current, eddy current, centrifugal force, suction force, and gravity to repeatedly impact, fluidize, disperse, shear, peel, and sort multi-scale particles. The required head and air volume of the circulating fan 600 for air classification are... Significantly reducing and effectively lowering the resistance of the classifier, significantly improving sorting efficiency, and reducing the circulating load, the lifting device replaces the internal pneumatic conveying with an external mechanical lifting method, based on the fact that the energy consumption of pneumatic material lifting is much greater than that of mechanical material lifting. This significantly reduces the pressure head and air volume of the system's circulating fan 600, while avoiding the high-speed airflow carrying material to scour the surfaces of various parts inside the mill, reducing wear, and extending the service life of the grinding media and other components. The grinding and classifying functions of the traditional internal circulation cement vertical mill are separated, and the production equipment is made intelligent by using methods such as mixing and feeding, coarse crushing and grinding, dispersing and lifting, and pre-selection and fine selection, thus achieving the effect of energy saving and consumption reduction.

[0068] The foregoing has shown and described the basic principles, main features, and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited to the above embodiments. The embodiments and descriptions in the specification are merely illustrative of the principles of the invention. Various changes and modifications can be made to the invention without departing from its spirit and scope, and all such changes and modifications fall within the scope of protection claimed by the present invention. The scope of protection of the present invention is defined by the appended claims and their equivalents.

Claims

1. A low-energy external circulation vertical roller mill for cement, comprising a mixing and feeding device disposed within the mill, and a grinding mechanism disposed at the bottom of the mixing and feeding device, the grinding mechanism comprising a housing and a grinding disc assembly disposed within the housing, characterized in that: An external circulation elevator fixed on the foundation is installed on the outside of the grinding mechanism. The inlet of the external circulation elevator is connected to the outlet of the grinding mechanism. The grinding material in the grinding mechanism is discharged to the outside of the grinding mechanism for external circulation through the external circulation elevator. It is then fed into the low-resistance high-efficiency classifier located above the grinding mechanism by mechanical lifting. The mixing and feeding device is configured to receive and mix the newly fed raw materials with the recycled material from the low-resistance high-efficiency classifier, and feed the mixture into the center of the grinding disc assembly of the grinding mechanism. The low-resistance high-efficiency air classifier is fixedly connected to the outer shell of the grinding mechanism. A set of feeding ports on its top is connected to the discharge port of a set of feed bins of the external circulation elevator. An air outlet on one side of its top is connected to a dust collector. The prepared material is fluidized and dispersed in the stratified fluidized dispersion chamber located in the middle of the low-resistance high-efficiency air classifier. The shear force of the horizontal velocity gradient is used to break up the particle agglomeration. The material enters the strong swirling classification zone and the forced eddy classification zone. In the swirling and eddy fields, the material is centrifugally settled and classified according to particle size, so as to realize the classification treatment of coarse and fine particles. The low-resistance high-efficiency air classifier also includes a sorting shell located in the middle of the air classifier. A primary air inlet is located on the lower periphery of the sorting shell, tangentially arranged in a group and evenly distributed. An air outlet shell is fixedly connected to the top of the sorting shell via flanges and bolts. A lower shell is located below the sorting shell, including a lower air ring at the top. The sorting shell has a double-layer cylindrical structure. An air outlet is fixedly connected to one side of the top of the air outlet shell, forming a 30° angle with the horizontal plane. A group of evenly distributed feed ports are fixedly connected to the bottom plate of the air outlet shell. The lower shell is fixedly connected to the lower part of the sorting shell and the outer shell of the grinding mechanism. A fixed connection is established, which, together with the sorting housing, forms a secondary air inlet. A transmission device is fixedly connected to the top of the air outlet housing. The transmission device consists of a variable frequency motor, a reducer, a shaft frame assembly, a vertical shaft, and a half-coupling. A sorting rotor is fixedly connected to the vertical shaft. The sorting rotor is cage-shaped and includes a rotor frame. A set of arc-shaped moving blades are evenly distributed around the rotor frame, along the rotation direction of the sorting rotor and at an angle of 12° to 47° to the center line of the sorting rotor. A material spreading disc is fixedly connected to the top of the sorting rotor. The material spreading disc includes a second ring located at the top. A set of annular sealing blades is fixedly connected to the outer side of the second ring. The second ring and the sealing blades... The upper end of the disc is inserted into the sealing groove at the bottom of the air outlet housing. A set of spreading columns and a set of spreading plates are fixedly connected to the top of the outer periphery of the spreading disc. The spreading columns and spreading plates are perpendicular to the spreading disc and evenly distributed. A layered impact guiding assembly is fixedly connected to the top of the sorting housing. The layered impact guiding assembly has a ring-shaped structure, which includes a first ring, an impact guiding cone, and a connecting plate. The first ring is fixedly connected to the inside of the upper layer of the sorting housing. The impact guiding cone forms a 60° angle with the horizontal plane and is fixedly connected to the first ring through the connecting plate. A fixing ring is provided at the bottom of the layered impact guiding assembly, which includes an outer ring fixedly connected to the inside of the upper layer of the sorting housing. The outer ring is fixedly connected to the inner ring by a set of vertical stiffeners. The inner ring is fixedly connected to the inner ring plate-shaped combined air guide vanes, which include vortex vanes and plate-shaped air guide vanes. The upper part of the inner ring is fixedly connected to the fixed ring, and the lower part is fixedly connected to the inner collection hopper. The lower layer of the sorting shell is provided with an outer ring S-shaped blade, which includes a blade angle adjustment mechanism and an S-shaped air guide vane. The upper part of the outer ring is connected to the lower layer of the sorting shell by a pin shaft, and the lower part is connected to the outer collection hopper by a pin shaft. The sorting rotor is located inside the inner ring plate-shaped combined air guide vanes. The bottom of the outer collection hopper and the inner collection hopper are provided with a discharge port and a three-stage air inlet. A dynamic fluidization system is provided on one side of the layered impact guiding component, which includes a high-pressure axial flow fan, connecting pipes and a set of air nozzles. The air nozzles are located at the bottom of the air outlet shell and close to the layered impact guiding component. The air nozzles are aligned with the layered fluidization dispersion chamber and are evenly distributed. The primary air inlet, secondary air inlet and tertiary air inlet constitute the air intake system of the low-resistance high-efficiency classifier.

2. The low energy consumption, external circulation, cement vertical roller mill according to claim 1, characterized in that: The mixing and feeding device includes an inverted conical shell and a cylindrical shell fixedly connected to the lower end of the inverted conical shell. A feeding pipe is fixedly connected to the side wall of the inverted conical shell, and the feeding pipe is inclined.

3. The low energy consumption, external circulation, cement vertical roller mill of claim 1, wherein: The grinding mechanism also includes a drive device for driving the grinding disc assembly to rotate, and a set of grinding rollers located above the grinding disc assembly and cooperating with its top. One end of the grinding roller is fixedly connected to a roller sleeve, and the other end of the grinding roller is fixedly connected to a pressurizing device. The bottom plate of the outer shell is fixedly connected to a discharge pipe and an air inlet. An air guide ring is fixedly connected inside the outer shell. An annular air duct is formed between the upper outer periphery of the grinding disc assembly and the air guide ring. The grinding disc assembly includes a disc base. The bottom of the disc base is fixedly connected to the output end of the drive device. A set of liners is fixedly connected to the upper surface of the disc base. A spherical groove grinding track is formed between the liners. A baffle ring is fixedly connected to the upper surface of the outer edge of the disc base. A scraper frame is fixedly connected to the bottom of the lower surface of the upper part of the disc base. A set of scraper plates is fixedly connected to the scraper frame. The scraper plates are distributed in the lower outer periphery of the disc base, located in the annular space between the grinding disc assembly and the outer shell. A mixer is set at the top center of the grinding disc assembly.

4. A low specific energy external circulation cement vertical roller mill according to claim 3, characterized in that: The grinding rollers are distributed at equal angles around the center of the grinding disc assembly. The axial center line of each grinding roller is inclined at an angle of less than or equal to 12° with the horizontal plane. Each grinding roller is arranged at equal angles and distances to each other on the horizontal plane. The grinding surface of the roller sleeve is a conical drum-shaped spherical surface with an annular groove in the middle of the spherical surface. Its outer surface is made of wear-resistant material. The total projected area of ​​the grinding rollers on the grinding disc assembly is 45% to 60% of the grinding track area. The wind speed V of the annular channel between the upper outer periphery of the grinding disc and the air guide ring inside the outer shell is 6m / s to 8m / s.

5. The low energy consumption, outer loop cement vertical roller mill of claim 1, wherein: The material distribution bin is located at the top of the low-resistance high-efficiency classifier and serves as the discharge port of the external circulation elevator, used to evenly distribute the ground material into the low-resistance high-efficiency classifier.

6. The low energy outotecement vertical roller mill of claim 1, wherein: The low-resistance high-efficiency classifier is fixedly connected to the outer shell of the grinding mechanism. The stratified fluidized dispersion chamber is located on the upper layer of the classification shell, and the lower layer of the classification shell is provided with a classification zone, namely a strong cyclone classification zone and a forced vortex classification zone. The stratified fluidized dispersion chamber is surrounded by a feeding disc and a stratified impact guiding component. The strong cyclone classification zone is annular, surrounded by an outer ring of annular S-shaped guide vanes and an inner ring of plate-shaped combined guide vanes, forming a channel for separating coarse and fine particles and guiding fine particles. The forced vortex classification zone is annular, surrounded by an inner ring of plate-shaped combined guide vanes and a classification rotor, forming a channel for separating small particles and powdery materials and guiding the selected finished product. The outer ring of annular S-shaped vanes is located outside the strong cyclone classification zone, and the inner ring of plate-shaped combined guide vanes is located inside the strong cyclone classification zone.

7. The low-energy external circulation vertical roller mill for cement according to claim 6, characterized in that: The external hopper is located in the lower part of the strong vortex classification zone and collects large particles after coarse separation. The internal hopper is located in the lower part of the forced vortex classification zone and collects small particles that fall vertically after separation. The internal hopper is fixedly connected to the external hopper. The external hopper is located inside the lower shell and is fixedly connected to the lower air ring.

8. The low-energy external circulation vertical roller mill for cement according to claim 7, characterized in that: The adjustable range of the nozzle wind speed V1 in the strong vortex classification zone is 15 m / s to 25 m / s, the inlet wind speed V2 at the inner ring plate-shaped combined air guide blades is 4 m / s to 5 m / s, the design range of the nozzle wind speed V3 in the forced vortex classification zone is 9 m / s to 12 m / s, the design range of the ratio of the sorting rotor diameter to its height D / H is 1.5 to 1.6, the design range of the inlet wind speed V4 between the sorting rotor blades is 2.7 m / s to 3.5 m / s, and the adjustable range of the rotational linear velocity V5 of the outer diameter of the sorting rotor is 22 m / s to 27 m / s.

9. The method of using the low-energy external circulation cement vertical roller mill according to any one of claims 1-8, characterized in that, The steps are as follows: S1. Mixing and feeding: The newly fed cement raw materials and the recycled material from the low-resistance high-efficiency separator are mixed in the mixing and feeding device and then fed into the center of the grinding disc assembly of the grinding mechanism. S2. Coarse crushing and grinding: By starting the drive device and pressurizing device of the grinding mechanism, the grinding disc assembly is rotated and pressure is applied to the grinding roller. Under the centrifugal force of the grinding disc assembly, the material enters the grinding track to form a material layer, so that a coarse crushing chamber and a grinding chamber with a reasonable distribution of multi-dimensional force field are formed between the grinding roller sleeve and the grinding disc assembly liner. Under the crushing of the grinding roller, the material is crushed in sequence through the coarse crushing chamber and the grinding chamber. S3. Dispersion and Lifting: Most of the ground material is dispersed by the rotating scraper and discharged. It is then mechanically lifted by the external circulation elevator, and after being evenly distributed in the distribution bin, it is fed into the low-resistance high-efficiency classifier. S4. Pre-selection and fine selection: The material entering the low-resistance high-efficiency air classifier is fluidized and initially dispersed in the stratified fluidized dispersion chamber, and then enters the strong vortex classification zone. Coarse particles are separated under the action of centrifugal force and velocity gradient shear and fall into the external collection hopper. Fine particles and powdery materials enter the forced vortex classification zone, where they are separated under the combined action of centrifugal force generated by the sorting rotor and airflow suction. Powdery materials with qualified fineness are discharged from the air outlet with the airflow and collected by the dust collector. Fine particles with unqualified fineness are separated and fall into the internal collection hopper. Coarse particles and fine particles are returned to the mixing and feeding device as recycled materials and re-enter the grinding mechanism for a new round of grinding.

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