Roller press pre-grinding system and its regulation method

Abstract

The application relates to the technical field of cement production, and discloses a roller press pre-grinding system and a regulation method thereof. The system comprises a flow stabilizing bin, a roller press, a scattering and grading machine, a cement mill and a powder concentrator which are sequentially connected, and further comprises an air guide device arranged at a dust collection air inlet at the top of the flow stabilizing bin, a dust collection device connected with a frequency converter, a flow detection device, a fineness detection device and a control system. The air guide device is adjustable in opening degree and is used for pre-screening materials in the dust collection airflow to block coarse particles. A discharge outlet of the dust collection device is connected to a feeding end of a second lifting device through an air chute. According to a grinding material flow signal and a 45-micron sieve residue value of the dust collection material, the control system cooperatively adjusts the opening degree of the air guide device and the operating frequency of the dust collection device, so that the particle size of the dust collection material is stably kept within a target range. The application realizes accurate regulation and control of the particle size of the dust collection material through local modification, has the remarkable effects of reducing energy consumption, improving product quality and reducing equipment wear.

Description

Technical Field

[0001] This application relates to the field of cement production technology, specifically to a pre-grinding system for a roller press and its control method. Background Technology

[0002] The roller press combined grinding system is one of the mainstream processes in cement grinding production, typically consisting of core equipment such as a stabilizing silo, roller press, dispersing and classifying machine, cement mill, and air classifier. In existing technology, material enters the roller press for crushing in the stabilizing silo, then is fed to the dispersing and classifying machine for pre-classification. Coarse particles are returned to the stabilizing silo for recirculation and crushing, while fine particles are fed into the cement mill for grinding. A dust collection inlet is located at the top of the stabilizing silo; a dust collection fan draws dust to a dust collector for collection, and the collected material is directly fed into the cement mill.

[0003] The existing technology has the following technical problems: (1) There is no material control device at the dust collection air inlet at the top of the stable flow bin. The dust collection airflow carries a large number of coarse and fine particles into the pipeline. The coarse particles scour the pipe wall, causing severe wear and exacerbating material segregation. The roller press has a large vibration amplitude and high maintenance cost. (2) The dust collection fan is controlled by the power frequency and cannot adjust the air volume according to the material flow rate. The particle size of the dust collection material fluctuates violently, and the over-grinding phenomenon is prominent. The circulating load is as high as 280% or more. (3) The dust collection material is directly fed into the mill and the flow rate cannot be accurately controlled. It is easy to stop the material and shake the mill. The conveyor belt starts and stops frequently, increasing energy consumption and shortening the equipment life. (4) The grinding media loading is too high, exceeding 85%. The power consumption of the cement process reaches 30kW·h / t, which exceeds the energy consumption limit. The specific surface area of ​​the finished product is only 300-310㎡ / kg, which is difficult to meet the high-end demand.

[0004] To address the aforementioned issues, existing improvement solutions often require large-scale structural modifications to the original system, resulting in high investment and long construction periods. These solutions fail to meet the requirements of technical upgrades that do not alter the original process layout, control investment, and achieve short construction periods. Summary of the Invention

[0005] In view of the above problems, this application provides a roller press pre-grinding system and its control method, which can achieve precise control of the particle size of the dust-collecting material without changing the original overall process layout, thereby reducing energy consumption and improving product quality.

[0006] According to one aspect of the embodiments of this application, a roller press pre-grinding system and its control method are provided. The roller press pre-grinding system and its control method include a flow stabilizing chamber, a roller press, a first lifting device, a dispersing and classifying machine, a cement mill, a second lifting device, and an air classifier, connected sequentially. The bottom of the air classifier is connected to the inlet pipe of the cement mill via a first return pipe, and the dispersing and classifying machine is connected to the top of the flow stabilizing chamber via a second return pipe. The system is characterized by further comprising: An air guide device is installed at the dust collection air inlet at the top of the flow stabilizing chamber. Its opening is adjustable and it is used to pre-screen the material in the dust collection airflow to prevent coarse particles from entering the dust collection pipe. The dust collection device has its air inlet connected to the dust collection air inlet at the top of the flow stabilizing chamber. The dust collection device is connected to a frequency converter. The discharge port of the dust collection device is connected to the inlet of the second lifting device through an air chute. A flow detection device is installed on the material conveying path into the mill to detect the flow rate of the material entering the mill and output a flow signal. Fineness detection device is used to detect the 45μm sieve residue value of the material entering the dust collection device after being screened by the air guide device; The control system is connected to the air guide device, the frequency converter, the flow detection device, and the fineness detection device respectively. The control system adjusts the opening of the air guide device and the operating frequency of the dust collection device in coordination with the flow signal and the 45μm sieve residue value to keep the 45μm sieve residue of the collected dust material stable within the target range.

[0007] In some embodiments, the air guiding device is a double-layer stainless steel insulating air guiding plate, the opening of which is continuously adjustable within the range of 0-100%.

[0008] In some embodiments, the variable frequency drive is a variable frequency drive that is continuously adjustable from 0 to 50 Hz.

[0009] In some embodiments, the control system is a DCS control system, which has a built-in flow-opening-frequency matching parameter table; The DCS control system collects the flow signal of the flow detection device and the 45μm sieve residue value of the fineness detection device every 3 seconds, and automatically outputs control commands for the opening degree of the air guide device and the operating frequency of the dust collection device according to the matching parameter table.

[0010] In some embodiments, the DCS control system is also signal-connected to at least one of the following: a stabilizing silo level detection device, a dust collector fan current detection device, a mill current detection device, and a system negative pressure detection device, for acquiring system operating status parameters and participating in coordinated control.

[0011] According to another aspect of this application, a method for controlling the particle size of dust-collected materials based on the above-mentioned roller press pre-grinding system is provided, comprising the following steps: The flow rate signal of the material entering the mill is obtained through the flow detection device, and the 45μm sieve residue value of the material entering the dust collection device after being screened by the air guide device is obtained through the fineness detection device. The control system adjusts the opening of the air guide device and the operating frequency of the dust collection device in coordination with the material flow signal and the 45μm sieve residue value to keep the 45μm sieve residue of the material entering the dust collection device stable within the target range. The dust collected by the dust collection device is sent to the second lifting device through the air chute, and then merges with the discharge from the cement mill before entering the air classifier for secondary sorting.

[0012] In some embodiments, in the step of coordinating the opening degree of the air guiding device and the operating frequency of the dust collection device: When the flow rate of material entering the mill increases or the residue on the 45μm sieve exceeds the upper limit of the target range, the opening of the air guide device is increased and the operating frequency of the dust collection device is increased. When the flow rate of material entering the mill decreases or the residue on the 45μm sieve is less than the lower limit of the target range, the opening of the air guide device is reduced and the operating frequency of the dust collection device is decreased.

[0013] In some embodiments, the target range for the 45μm sieve residue is 43%–47%.

[0014] In some embodiments, the target range for controlling the opening of the air guide device is 60%–70%, and the target range for controlling the operating frequency of the dust collection device is 35Hz–45Hz.

[0015] In some embodiments, the control system acquires the feed material flow signal and the 45μm sieve residue value every 3 seconds, and automatically outputs control commands according to the built-in flow-opening-frequency matching parameter table.

[0016] The beneficial effects of this application are: 1. This application solves the problem of large particle size fluctuations in dust collection materials by installing an adjustable air guide device at the top dust collection inlet of the stable flow bin and equipping the dust collection device with a variable frequency speed controller. Combined with a flow detection device and a fineness detection device, the control system adjusts the opening of the air guide device and the operating frequency of the dust collection fan in a coordinated manner based on the flow rate signal of the material entering the mill and the 45μm sieve residue value of the dust collection material. This forms a closed-loop coordinated control system of "material flow rate - air guide plate opening - fan frequency", which stabilizes the 45μm sieve residue of the dust collection material within the target range of 43%-47%.

[0017] 2. The air guide device in this application can also pre-screen the material in the dust collection airflow by adjusting its own opening, reducing the entry of coarse particles into the dust collection pipe, avoiding the scouring and wear of the pipe wall by coarse particles in the high-speed airflow, and improving the segregation of materials in the stable flow chamber, thereby reducing the vibration amplitude of the roller press by 40% and significantly reducing equipment maintenance costs.

[0018] 3. In this application, through the frequency conversion modification and coordinated control of the fan, the air volume of the dust collection fan can be supplied on demand, avoiding the excess air volume during the operation of the power frequency. At the same time, the stability of the particle size of the dust collection material and the elimination of the over-grinding phenomenon enable the loading of the cement mill grinding media to be reasonably reduced, the operating load to be reduced, and the power consumption of the cement process to be greatly reduced.

[0019] 4. In this application, the amount of dust-collected material entering the mill can be precisely controlled by the air guide device, thereby solving the problem of material stopping and mill shaking caused by excessive material flow. The number of times the conveyor belt entering the mill starts and stops is reduced from more than 10 times per month to 0 times, which greatly reduces equipment impact and wear and effectively extends the service life of the conveying equipment and cement mill.

[0020] The above description is only an overview of the technical solution of this application. In order to better understand the technical means of this application and to implement it in accordance with the contents of the specification, and to make the above and other objects, features and advantages of this application more obvious and understandable, the following are specific embodiments of this application. Attached Figure Description

[0021] Various other advantages and benefits will become apparent to those skilled in the art upon reading the following detailed description of preferred embodiments. The accompanying drawings are for illustrative purposes only and are not intended to limit the scope of this application. Furthermore, the same reference numerals denote the same parts throughout the drawings. In the drawings: Figure 1 This is a system diagram of the pre-grinding system of the roller press provided in the embodiments of this application.

[0022] The reference numerals in the detailed embodiments are as follows: Roller press pre-grinding system 100, flow stabilizing chamber 110, air guide device 111, roller press 120, first lifting device 130, dispersing and classifying machine 140, second return pipe 141, cement mill 150, flow detection device 151, second lifting device 160, air classifier 170, first return pipe 171, dust collection device 180, frequency converter 181, fineness detection device 182, air chute 183. Detailed Implementation

[0023] The embodiments of the technical solution of this application will be described in detail below with reference to the accompanying drawings. The following embodiments are only used to more clearly illustrate the technical solution of this application, and are therefore merely examples and should not be used to limit the scope of protection of this application. Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application pertains; the terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit this application; the terms "comprising" and "having," and any variations thereof, in the specification, claims, and the foregoing description of the accompanying drawings are intended to cover non-exclusive inclusion.

[0024] For details, please refer to Figure 1 , Figure 1 This is a system diagram of the pre-grinding system of the roller press provided in this application embodiment. The pre-grinding system 100 of the roller press 120 includes a stabilizing bin 110, a roller press 120, a first lifting device 130, a dispersing and classifying machine 140, a cement mill 150, a second lifting device 160, and a classifier 170 connected in sequence. The stabilizing bin 110 is used to store materials from the batching station and stably feed them to the roller press 120. The roller press 120 is used to perform high-pressure extrusion and crushing of the materials. The dispersing and classifying machine 140 is used to disperse the extruded materials and separate qualified fine powder. The cement mill 150 is used to perform final grinding of the fine powder. The classifier 170 is used to classify the mill output and output finished product. The bottom of the classifier 170 is connected to the inlet pipe of the cement mill 150 through a first return pipe 171. The coarse powder separated by the classifier 170 is returned to the cement mill 150 for re-grinding through the first return pipe 171, forming a mill circulation loop. The dispersing and classifying machine 140 is connected to the top of the stabilizing chamber 110 via a second return pipe 141. The second return pipe 141 is used to return the coarse particles separated by the dispersing and classifying machine 140 to the stabilizing chamber 110 to mix with the incoming material before re-entering the roller press 120 for extrusion, forming a circulation loop in the roller press 120. This system also includes: The air guide device 111 is installed at the dust collection air inlet at the top of the flow stabilizing chamber 110. Its opening is adjustable and it is used to pre-screen the material in the dust collection airflow to prevent coarse particles from entering the dust collection pipe. The air guide device 111 can adjust the airflow speed at the dust collection air inlet and the upper limit of the allowable material particle size by changing its own opening, thereby realizing the active classification and screening of the material carried in the dust collection airflow.

[0025] The dust collection device 180 has its air inlet connected to the dust collection air inlet at the top of the stabilizing chamber 110. The dust collection device 180 is connected to a variable frequency drive 181, which adjusts the operating speed of the internal fan of the dust collection device 180, thereby changing the air volume and negative pressure of the dust collection system. The discharge port of the dust collection device 180 is connected to the inlet of the second lifting device 160 via an air chute 183. The air chute 183 utilizes the principle of air conveying to fluidize and enclose the material collected by the dust collection device 180, allowing it to merge with the discharge from the cement mill 150 before entering the classifier 170 for secondary sorting, thus avoiding over-grinding caused by the direct entry of the dust collection material into the mill.

[0026] The flow detection device 151 is installed on the material conveying path into the mill. It is used to detect the flow rate of the material into the mill and output the flow signal. The flow detection device 151 can be a solid flow meter or a belt scale. It continuously detects the instantaneous flow rate of the material during the conveying process and provides real-time data of the amount of material entering the mill to the control system as an important input parameter for feedforward control.

[0027] Fineness detection device 182 is used to detect the 45μm sieve residue value of the material entering the dust collection device 180 after being screened by the air guide device 111. The fineness detection device 182 is preferably an online laser particle size analyzer or an online sieve residue analyzer, which is installed on the material conveying pipeline of the dust collection device 180 and can continuously and in real time detect the 45μm sieve residue value of the dust collection material and transmit the detection signal to the control system.

[0028] The control system is connected to the air guide device 111, the frequency converter 181, the flow detection device 151 and the fineness detection device 182 respectively. The control system adjusts the opening degree of the air guide device 111 and the operating frequency of the dust collection device 180 in coordination with the flow signal and the 45μm sieve residue value so that the 45μm sieve residue of the dust collection material is kept stable within the target range.

[0029] In this embodiment of the application, during the operation, the material from the batching station first enters the stabilizing silo 110. The material in the stabilizing silo 110 continuously and stably enters the roller press 120. After being crushed by the roller press 120, it is sent to the dispersing and classifying machine 140 through the first lifting device 130. The dispersing and classifying machine 140 disperses the extruded material cake and pre-classifies it according to particle size. The coarse particles are returned to the stabilizing silo 110 through the second return pipe 141 and mixed with the incoming material before re-entering the roller press 120 for cyclic extrusion. The fine particles are sent to the cement mill 150 for grinding. The output of the cement mill 150 is sent to the classifier 170 through the second lifting device 160 for finished product sorting. The fine powder sorted by the classifier 170 is stored as finished product, and the coarse powder is returned to the cement mill 150's inlet pipe through the first return pipe 171 for further grinding. In the aforementioned continuous production process, the flow detection device 151, installed on the material conveying path into the mill, detects the flow rate of the material entering the mill in real time and outputs a flow signal. The fineness detection device 182 continuously detects the 45μm sieve residue value of the material entering the dust collection device 180 after being screened by the air guide device 111. The control system periodically collects the flow signal and the 45μm sieve residue value and outputs control commands to coordinate the adjustment of the opening degree of the air guide device 111 and the operating frequency of the dust collection device 180. When the flow rate of the material entering the mill increases or the 45μm sieve residue value is greater than the upper limit of the target range, the opening degree of the air guide device 111 is increased and the operating frequency of the dust collection device 180 is increased to enhance the screening and suction capabilities. When the flow rate of the material entering the mill decreases or the 45μm sieve residue value is less than the lower limit of the target range, the opening degree of the air guide device 111 is decreased and the operating frequency of the dust collection device 180 is reduced to reduce sieving and energy consumption. This ensures that the 45μm sieve residue of the dust-collected material remains stable within the target range of 43%–47%, achieving precise closed-loop control of the particle size of the dust-collected material.

[0030] In some embodiments, the air guide device 111 is a double-layer stainless steel isolation air guide plate, the opening of which is continuously adjustable within the range of 0-100%. In this embodiment, the double-layer stainless steel isolation air guide plate is made of wear-resistant and high-temperature resistant stainless steel. Its double-layer structure design can form a multi-stage deflection path in the dust collection airflow channel. When the dust-laden airflow passes through, coarse particles will impact and adhere to the surface of the air guide plate due to inertia, and fall back into the flow stabilization chamber 110 under gravity, while fine particles will pass smoothly with the airflow, thereby achieving a highly efficient pre-screening effect. At the same time, the continuous opening adjustment range of 0-100% allows the air guide device 111 to be steplessly and precisely adjusted according to changes in working conditions, adapting to the screening requirements under different material flow rates and particle size compositions, and avoiding control lag or overshoot problems caused by dead zones in the opening adjustment.

[0031] In some embodiments, the variable frequency drive 181 is a frequency converter that is continuously adjustable from 0 to 50 Hz. In this embodiment, the frequency converter achieves stepless variation of the fan speed within the rated speed range by continuously adjusting the power supply frequency of the dust collection fan motor, thereby precisely controlling the air volume and operating negative pressure of the dust collection system. Compared with the traditional power frequency operation mode, it can effectively avoid the energy waste caused by excessive air volume and the deterioration of dust collection effect caused by insufficient air volume.

[0032] In some embodiments, the control system is a DCS control system, which has a built-in flow-opening-frequency matching parameter table. The DCS control system collects the flow signal from the flow detection device 151 and the 45μm sieve residue value from the fineness detection device 182 every 3 seconds, and automatically outputs control commands for the opening of the air guide device 111 and the operating frequency of the dust collection device 180 according to the matching parameter table. The DCS control system has data processing and logic operation capabilities. Its built-in matching parameter table can be obtained by training based on a large amount of historical production data, covering the optimal matching combination of the opening of the air guide device 111 and the frequency of the dust collection fan under different material flow ranges. The rapid acquisition cycle of once every 3 seconds ensures that the system can promptly sense the transient changes in the flow rate of the material entering the mill and the fineness of the dust collected material, and complete the calculation and command output in a very short time, thereby realizing real-time, dynamic and precise control of the particle size of the dust collected material and avoiding particle size fluctuations caused by control lag.

[0033] In some embodiments, the DCS control system is also signal-connected to at least one of the following: a level detection device for the stabilizing silo 110, a current detection device for the dust collector fan, a current detection device for the mill, and a negative pressure detection device for the system. These devices are used to acquire system operating status parameters and participate in coordinated control. In this embodiment, the aforementioned detection devices monitor the real-time operating conditions of the system. The level detection device for the stabilizing silo 110 monitors the material level height within the silo to prevent material interruption in the roller press 120 due to excessively low material levels or material overflow due to excessively high material levels. The current detection device for the dust collector fan monitors changes in fan load to determine whether the dust collection system is blocked or experiencing abnormally high resistance. The current detection device for the mill indirectly reflects the material filling amount and grinding state within the mill. When the mill current abnormally increases, it can optimize the flow distribution in a timely manner to reduce coarse powder entering the mill. The negative pressure detection device for the system monitors the negative pressure distribution of the entire dust collection network to ensure that the system operates within the optimal negative pressure range. The introduction of the aforementioned multi-source detection signals enables the DCS control system to comprehensively judge the overall operating condition of the system. While coordinating the adjustment of the opening of the air guide device 111 and the frequency of the dust collection fan, it also takes into account the material level balance of the flow stabilizing bin 110, the safe operation of the dust collection system, and the mill load control, thereby achieving system-level multi-objective collaborative optimization control.

[0034] According to another aspect of this application, a method for controlling the particle size of dust-collecting materials based on the pre-grinding system 100 of the roller press 120 is provided, comprising the following steps: The flow rate signal of the material entering the mill is obtained by the flow detection device 151, and the 45μm sieve residue value of the material entering the dust collection device 180 after being screened by the air guide device 111 is obtained by the fineness detection device 182. The control system coordinates the opening of the air guide device 111 and the operating frequency of the dust collection device 180 based on the material flow signal and the 45μm sieve residue value, so that the 45μm sieve residue of the material entering the dust collection device 180 is kept within the target range. The dust collected by the dust collection device 180 is sent to the second lifting device 160 through the air chute 183, and then merges with the discharge of the cement mill 150 and enters the air classifier 170 for secondary sorting.

[0035] In some embodiments, in the step of coordinating the opening degree of the air guiding device 111 and the operating frequency of the dust collection device 180: When the flow rate of material entering the mill increases or the residue on the 45μm sieve exceeds the upper limit of the target range, the opening of the air guide device 111 is increased and the operating frequency of the dust collection device 180 is increased. When the flow rate of material entering the mill decreases or the residue on the 45μm sieve is less than the lower limit of the target range, the opening of the air guide device 111 is reduced and the operating frequency of the dust collection device 180 is lowered.

[0036] In some embodiments, the target range for 45μm sieve residue is 43%–47%.

[0037] In some embodiments, the opening range of the air guide device 111 is controlled within 60%–70%, and the operating frequency of the dust collection device 180 is controlled within 35Hz–45Hz.

[0038] In some embodiments, the control system acquires the feed material flow signal and 45μm sieve residue value every 3 seconds, and automatically outputs control commands according to the built-in flow-opening-frequency matching parameter table.

[0039] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of this application, and not to limit them. Although the foregoing embodiments have provided a detailed description of this application, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features. These modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of this application, and they should all be covered within the scope of the claims and specification of this application. In particular, as long as there is no structural conflict, the various technical features mentioned in the embodiments can be combined in any way. This application is not limited to the specific embodiments disclosed herein, but includes all technical solutions falling within the scope of the claims.

Claims

1. A roller press pre-grinding system, comprising a flow stabilizing chamber, a roller press, a first lifting device, a dispersing and classifying machine, a cement mill, a second lifting device, and an air classifier connected in sequence, wherein the bottom of the air classifier is connected to the inlet pipe of the cement mill via a first return pipe, and the dispersing and classifying machine is connected to the top of the flow stabilizing chamber via a second return pipe, characterized in that, Also includes: An air guide device is installed at the dust collection air inlet at the top of the flow stabilizing chamber. Its opening is adjustable and it is used to pre-screen the material in the dust collection airflow to prevent coarse particles from entering the dust collection pipe. The dust collection device has its air inlet connected to the dust collection air inlet at the top of the flow stabilizing chamber. The dust collection device is connected to a frequency converter. The discharge port of the dust collection device is connected to the inlet of the second lifting device through an air chute. A flow detection device is installed on the material conveying path into the mill to detect the flow rate of the material entering the mill and output a flow signal. Fineness detection device is used to detect the 45μm sieve residue value of the material entering the dust collection device after being screened by the air guide device; The control system is connected to the air guide device, the frequency converter, the flow detection device, and the fineness detection device respectively. The control system adjusts the opening of the air guide device and the operating frequency of the dust collection device in coordination with the flow signal and the 45μm sieve residue value to keep the 45μm sieve residue of the collected dust material stable within the target range.

2. The pre-grinding system of the roller press according to claim 1, characterized in that, The air guide device is a double-layer stainless steel isolation air guide plate, and its opening degree is continuously adjustable within the range of 0-100%.

3. The pre-grinding system for a roller press according to claim 1, characterized in that, The variable frequency drive is a continuously adjustable frequency converter from 0 to 50 Hz.

4. The pre-grinding system of the roller press according to claim 1, characterized in that, The control system is a DCS control system, which has a built-in flow-opening-frequency matching parameter table. The DCS control system collects the flow signal of the flow detection device and the 45μm sieve residue value of the fineness detection device every 3 seconds, and automatically outputs control commands for the opening degree of the air guide device and the operating frequency of the dust collection device according to the matching parameter table.

5. The pre-grinding system of the roller press according to claim 4, characterized in that, The DCS control system is also connected to at least one of the following: a steady flow silo level detection device, a dust collector fan current detection device, a mill current detection device, and a system negative pressure detection device, for acquiring system operating status parameters and participating in coordinated control.

6. A method for controlling the particle size of dust-collecting materials using the pre-grinding system of a roller press according to any one of claims 1 to 5, characterized in that, Includes the following steps: The flow rate signal of the material entering the mill is obtained through the flow detection device, and the 45μm sieve residue value of the material entering the dust collection device after being screened by the air guide device is obtained through the fineness detection device. The control system adjusts the opening of the air guide device and the operating frequency of the dust collection device in coordination with the material flow signal and the 45μm sieve residue value to keep the 45μm sieve residue of the material entering the dust collection device stable within the target range. The dust collected by the dust collection device is sent to the second lifting device through the air chute, and then merges with the discharge from the cement mill before entering the air classifier for secondary sorting.

7. The method according to claim 6, characterized in that, In the steps of coordinating the opening of the air guide device and the operating frequency of the dust collection device: When the flow rate of material entering the mill increases or the residue on the 45μm sieve exceeds the upper limit of the target range, the opening of the air guide device is increased and the operating frequency of the dust collection device is increased. When the flow rate of material entering the mill decreases or the residue on the 45μm sieve is less than the lower limit of the target range, the opening of the air guide device is reduced and the operating frequency of the dust collection device is decreased.

8. The method according to claim 7, characterized in that, The target range for the 45μm sieve residue is 43%–47%.

9. The method according to claim 7, characterized in that, The target range for controlling the opening of the air guide device is 60%–70%, and the target range for controlling the operating frequency of the dust collection device is 35Hz–45Hz.

10. The method according to claim 7, characterized in that, The control system acquires the flow rate signal of the material entering the mill and the residue value of the 45μm sieve every 3 seconds, and automatically outputs control commands according to the built-in flow-opening-frequency matching parameter table.

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