Solid waste powder particle grading automatic detection and regulation device and method
By integrating online laser particle size detection, mechanical ball milling, and PLC automatic control system, the system achieves automated, traceable, and precise control of solid waste powder particle size distribution. This solves the problems of fragmented detection and control, large errors from manual intervention, and difficulties in the coordinated distribution of multiple solid wastes, thereby improving the control accuracy and repeatability of the entire solid waste cementation system.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- RESEARCH INSTITUTE OF WATER CONSERVANCY & HYDROPOWER IN XINJIANG UYGUR AUTONOMOUS REGION
- Filing Date
- 2026-05-09
- Publication Date
- 2026-06-16
AI Technical Summary
In the existing technology, the detection and control of particle size distribution of solid waste powder has problems such as the separation of detection and control, large errors in human intervention, difficulty in the synergistic gradation of multiple solid wastes, and lack of process data. As a result, the particle size distribution control accuracy is low and the repeatability is poor, which cannot meet the needs of the whole solid waste cementation system.
By integrating online laser particle size detection, mechanical ball milling, vibrating sieve grading, and PLC automatic control system, the system achieves automated, traceable, and precise control of particle size distribution of multi-source solid waste powder. Through multi-compartment metering feeding, closed-loop control, and full-process data acquisition, an integrated closed loop of detection and control is formed.
It achieves real-time linkage response between particle size detection and grinding control, multi-source solid waste co-feeding, high control accuracy, complete data recording, significantly improves the dynamic tracking accuracy and repeatability of particle size distribution control, and supports the industrial application of the whole solid waste gelation system.
Smart Images
Figure CN122209552A_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the fields of building material preparation and industrial solid waste resource utilization, and in particular to an automatic detection and control device and method for solid waste powder particle size distribution. Background Technology
[0002] With the escalating global resource crisis and the advancement of the "dual carbon" goal, the efficient utilization of industrial solid waste has become an important research direction in the field of building materials. Typical mining solid wastes such as fly ash, coal gangue, steel slag, blast furnace slag, tailings, and desulfurization gypsum have an annual output exceeding 3 billion tons. Traditional cement production relies on limestone mining, and CO2 emissions during the production process account for 11% of global greenhouse gas emissions. Therefore, there is an urgent need to develop an all-solid-waste cementitious material system that can replace cement.
[0003] In the research and preparation of solid waste cementitious materials, the particle size distribution of solid waste powder is a key fundamental parameter determining the performance of the cementitious system. Based on the close-packed theory (Fuller equation, Andreasen equation), a reasonable combination of solid waste particles of different sizes can significantly reduce the system porosity, optimize the microstructure of the interfacial transition zone (ITZ), and improve the growth space of hydration products, thereby comprehensively improving the mechanical properties and durability of the material. Studies have shown that the 28-day compressive strength of the optimal particle size distribution system can be increased by 15%–30% compared to the random particle size distribution system, while the total porosity is reduced by 20%–40%.
[0004] However, the original particle size distributions of various industrial solid wastes, such as fly ash, coal gangue, steel slag, mineral slag, and tailings, vary significantly—fly ash D 50 Typically 10-30μm, steel slag D 50 The particle size ranges from 20 to 80 μm, while that of coal gangue and tailings is even wider (up to the millimeter level). Furthermore, the particle size distribution of the same solid waste can vary greatly depending on its source and the batch it is processed in. This makes it difficult to directly meet the precise requirements of the whole solid waste cementing system for particle size distribution. It must undergo a systematic process of "grinding-grading-testing" before it can be used.
[0005] Currently, the control of particle size distribution of solid waste powder in laboratory and industrial production typically relies on the following traditional methods: (1) Offline sampling and testing method: First, the solid waste is ground in batches by ball mill. After sampling, it is sent to an offline laser particle size analyzer for testing. Then, based on the test results, it is manually determined whether it needs to be ground or screened again, forming a multi-step manual cycle process of "grinding → stopping the machine → sampling → testing → judgment → grinding again". (2) Fixed screen grading method: The grinding products are mechanically graded by a vibrating screen with a fixed mesh size. The upper limit of particle size is controlled by the screen aperture, but it cannot achieve precise control of the full particle size distribution curve, and the operation of frequently changing screens is cumbersome. (3) Empirical grinding time control method: Relying on the operator's experience to set the ball mill running time to roughly infer the particle size, lacking a real-time feedback mechanism, the control accuracy is extremely low.
[0006] The aforementioned traditional technical solutions have the following significant drawbacks, which severely restrict the scientific and engineering advancement of research on the gradation of solid waste cementitious systems. Specifically, these drawbacks are as follows: 1) Disjointed Detection and Control: Particle size detection (offline sampling) and grinding control (manual intervention) are two independent processes. Information transmission relies on manual handling and input, resulting in significant problems such as long time delays (a single detection cycle typically takes 15-30 minutes) and low response efficiency, making it impossible to achieve precise real-time closed-loop control of particle size distribution. Over-grinding or under-grinding of particles occurs frequently, leading to raw material loss and energy waste.
[0007] 2) Accumulation of errors due to human intervention: Operators' interpretation of particle size detection data and adjustment of ball milling parameters are highly dependent on personal experience, resulting in strong subjectivity and arbitrariness. In comparative experiments of multiple solid waste compatibility systems (such as orthogonal experiments on the effect of particle size on gelling activity), the systematic error introduced by human operation between different batches can be as high as 10%-25%, seriously affecting the repeatability and reliability of solid waste gradation research results, making it difficult for basic research data to guide industrial-scale production.
[0008] 3) Difficulty in co-grading multiple solid wastes: Existing equipment typically only grinds single solid wastes, lacking the ability to co-meter and feed multiple solid waste powders, mix and grind them, and monitor the overall particle size distribution of the mixed system in real time. A complete solid waste gelling system usually contains 3-6 solid waste raw materials, and the synergistic matching of particle sizes among these materials is a prerequisite for achieving the theoretical effect of close packing, a requirement that existing equipment cannot meet.
[0009] 4) Lack of process data recording and traceability: Traditional processes lack a mechanism for synchronously recording key parameters (speed, time, temperature, amplitude) and particle size change curves during the grinding process, making it impossible to build a complete particle size control process database. Researchers cannot trace the particle size control history corresponding to a certain performance result, which is seriously detrimental to the optimization and accumulation of process parameters and subsequent industrial reproduction, forming a technical barrier of "research results - engineering disconnect".
[0010] Therefore, how to develop an automatic detection and control device for the particle size distribution of solid waste powder, and deeply integrate online laser particle size detection technology with mechanical ball milling, vibrating sieving and classification and PLC automatic control system to realize the automated monitoring and operation of the entire processing process, has become a technical problem that urgently needs to be solved by those skilled in the art. Summary of the Invention
[0011] The purpose of this invention is to provide an automatic detection and control device for the particle size distribution of solid waste powder, which integrates online laser particle size detection, mechanical ball milling, vibrating sieve grading, PLC closed-loop control, and full-process data acquisition and display to achieve high-precision, automated, and traceable precise control of the particle size distribution of multi-source solid waste powder; and to solve the four major problems in solid waste powder particle size distribution control technology: "disjointed detection and control, large errors from manual intervention, difficulty in co-feeding multiple solid wastes, and lack of process data".
[0012] To solve the above-mentioned technical problems, the present invention adopts the following technical solution: This invention discloses an automatic detection and control device for particle size distribution of solid waste powder, comprising: The multi-compartment metering and feeding unit includes at least three independent solid waste storage compartments. Each storage compartment is equipped with a variable frequency metering screw feeder at the bottom, which is used to simultaneously transport multiple solid waste raw materials to the connected collection buffer hopper below for mixing according to a preset mass ratio. A mechanical ball mill grinding unit includes a frequency converter-driven ball mill, wherein the feed inlet of the frequency converter-driven ball mill is connected to the discharge outlet of the collection buffer hopper, and is used to grind mixed solid waste. The vibrating screen grading unit includes at least two stacked vibrating screen assemblies, the feed end of which is connected to the discharge port of the ball mill, for classifying the ground products in a stepwise manner according to particle size. An online laser particle size detection unit includes an online laser particle size analyzer, wherein the sample inlet of the online laser particle size analyzer is connected to the fine particle outlet of the vibrating screen assembly, and is used to measure the particle size distribution data of the powder sample in real time. The closed-loop circulation pipeline unit includes a bucket elevator and a pneumatic diversion valve. The feed end of the bucket elevator is connected to the coarse particle discharge port of the vibrating screen assembly and the first discharge port of the diversion valve. The discharge end of the bucket elevator is connected to the feed port of the ball mill. The feed port of the diversion valve is connected to the discharge end of the online laser particle size analyzer. The second discharge port of the diversion valve is connected to the finished product discharge hopper. The PLC automatic control unit is electrically connected to the variable frequency metering screw feeder, the frequency converter of the ball mill, the excitation motor of the vibrating screen assembly, the online laser particle size analyzer, and the flow divider valve, respectively. The PLC automatic control unit has a built-in particle size distribution target curve database, which is used to receive the particle size distribution data measured in real time by the online laser particle size analyzer, compare the collected particle size distribution data with the target gradation curve, and automatically adjust the rotation speed of the ball mill, the excitation parameters of the vibrating screen assembly, and the on / off state of the flow divider valve according to the comparison results, forming a closed-loop control loop for online particle size detection and automatic grinding control. The data acquisition and display terminal is connected to the PLC automatic control unit and is used to display a comparison chart of particle size distribution data and target gradation curve in real time, and to record the process parameters of the whole process simultaneously.
[0013] Furthermore, the PLC automatic control unit has a built-in target particle size distribution curve database that pre-stores standard particle size distribution curves calculated based on the Fuller equation and / or the Andreasen equation; the PLC automatic control unit uses D50 deviation ≤ 5% and D90 deviation ≤ 8% as the particle size qualification threshold.
[0014] Furthermore, the vibrating screen assembly includes an upper screen and a lower screen stacked on top of each other. The upper screen has a mesh size of 200 mesh, and the lower screen has a mesh size of 400 mesh. The coarse particles intercepted by the upper screen are returned to the ball mill via the bucket elevator, while the fine particles screened by the lower screen are sent to the online laser particle size analyzer via a pneumatic conveying pipeline.
[0015] Furthermore, the ball mill's cylinder is filled with three different sizes of grinding media—large, medium, and small—designed according to gradation; the main motor of the ball mill is equipped with a variable frequency speed control device, and the speed adjustment range of the variable frequency speed control device is 40%–100% of the rated speed.
[0016] Furthermore, the online laser particle size analyzer adopts the dynamic light scattering principle or the laser diffraction principle, has a built-in dry dispersion system, and a single measurement cycle does not exceed 60 seconds; the online laser particle size analyzer is connected to the PLC automatic control unit through an RS485 digital signal interface, and the data transmission delay does not exceed 1 second.
[0017] Furthermore, the pneumatic diverter valve is a three-way diverter valve, and the switching response time of the pneumatic diverter valve is less than 0.5 seconds; when the PLC automatic control unit determines that the current particle size does not meet the target gradation, the diverter valve is connected to the return grinding channel of the ball mill feed inlet; when it is determined that the particle size meets the target gradation, the diverter valve is switched to the direction of the finished product discharge bin.
[0018] Furthermore, the data acquisition and display terminal is equipped with an industrial-grade waterproof touchscreen, and all process parameters are stored in a local database in timestamp format. It supports historical data query, comparative analysis, and export of CSV / Excel format data by time or batch.
[0019] An automatic detection and control method for particle size distribution of solid waste powder, applied to the device described above, includes the following steps: Step 1, Feeding and Mixing: Through the multi-compartment metering feeding unit, at least three solid waste raw materials are simultaneously metered and transported to the collection buffer hopper for mixing according to the preset mass ratio; Step 2, grinding: The mixed solid waste raw materials are fed into a variable frequency ball mill for grinding; Step 3, Classification: The milled product is fed into at least two stacked vibrating screen assemblies and classified in a stepwise manner according to particle size to obtain coarse and fine particles. Step 4, online detection: The graded fine particles are continuously fed into an online laser particle size analyzer to measure the particle size distribution data of the fine particles in real time, including the characteristic particle sizes of D10, D50, and D90 and the complete particle size distribution curve. Step 5, closed-loop control: The PLC automatic control unit receives real-time particle size distribution data, compares the real-time particle size distribution data with the built-in target gradation curve, and controls the diversion valve 7 to return the coarse particles to the mill and collect and output the qualified powder. Step 6, Data Recording: The comparison chart between the particle size distribution curve and the target gradation curve is displayed in real time throughout the entire process, and all process parameters are recorded in timestamp format.
[0020] Furthermore, the closed-loop control in step five includes: when the particle size distribution does not reach the target gradation, the PLC automatic control unit adjusts the rotation speed of the ball mill and / or the excitation parameters of the vibrating screen assembly, and controls the diversion valve to open the return grinding channel, so that the bucket elevator returns the coarse particles to the ball mill for further grinding. When the particle size distribution reaches the target gradation, the PLC automatic control unit controls the diversion valve to switch to the finished product discharge channel, collecting the qualified powder into the finished product discharge hopper.
[0021] Compared with the prior art, the beneficial technical effects of the present invention are as follows: (1) Integrated closed loop of detection and control with rapid response: The detection data of the online laser particle size analyzer directly drives the PLC to control the ball mill speed and the state of the diversion valve, realizing the real-time linkage response of particle size detection and grinding control (response delay <2 seconds), completely eliminating the time delay of 15-30 minutes in the offline detection method, greatly improving the dynamic following accuracy of gradation control, and the D50 control accuracy is better than ±5%.
[0022] (2) Multi-source solid waste co-feeding to meet the needs of the whole solid waste system: The multi-compartment metering feeding unit can simultaneously introduce three or more solid waste raw materials, and realize the co-mixing and particle size control of multiple solid waste particles during the grinding process. It can accurately meet the requirements of the whole solid waste cementing system for precise control of the comprehensive particle size distribution of multiple raw materials such as fly ash, coal gangue, and steel slag, and fundamentally solve the limitation of single solid waste treatment in the existing equipment.
[0023] (3) Built-in theoretical gradation model, high control accuracy and good repeatability: The PLC automatic control unit has a built-in standard gradation curve database based on the Fuller equation and the Andreasen equation, which provides users with theoretical optimization gradation reference. It also eliminates human experience intervention through fully automatic closed-loop control. Under the same process parameters, the same particle gradation results can be stably reproduced (batch repeatability RSD<5%), which significantly improves the data reliability and scientificity of multiple comparative experiments.
[0024] (4) Complete data retention throughout the process, supporting process optimization and reproduction: The device synchronously records the evolution of particle size curves, grinding parameters and time nodes throughout the process, and constructs a complete particle size control process database, providing traceable experimental data support for the optimization of the gradation of the solid waste cementing system. This effectively makes up for the serious defects of the traditional method of "no data retention and inability to reproduce", and provides a data foundation for the cross-batch optimization accumulation of process parameters and industrial scale-up.
[0025] (5) Easy to operate and wide range of applications: The equipment has a visual touch screen operation interface, and the operation steps are simple and standardized, reducing the dependence on the professional and technical level of personnel; the modular design of the device makes the switching and cleaning of different solid waste raw materials convenient and efficient, and is suitable for particle size distribution control of various mining solid waste powders such as fly ash, coal gangue, steel slag, slag, and tailings, and has good prospects for promotion and application.
[0026] In summary, the automatic detection and control device for solid waste powder particle size distribution of this invention achieves an integrated closed-loop detection and control system with a response delay of less than 2 seconds and a D50 control accuracy better than ±5%. It supports multi-source co-feeding of solid waste, meeting the needs of a complete solid waste system. It incorporates a theoretical particle size distribution model, achieving batch repeatability RSD of less than 5% and high control accuracy. Complete data retention throughout the entire process provides a traceable basis for process optimization. This invention is simple to operate, has a wide range of applications, and shows promising prospects for application in the control of particle size distribution in mining solid waste powder. Attached Figure Description
[0027] The present invention will be further described below with reference to the accompanying drawings.
[0028] Figure 1 This is a schematic diagram of the automatic detection and control device for particle size distribution of solid waste powder according to the present invention. Figure 2 This is a flowchart of the automatic detection and control method for particle size distribution of solid waste powder according to the present invention.
[0029] Explanation of reference numerals in the attached diagram: 1. Solid waste storage silo; 2. Aggregate buffer hopper; 3. Variable frequency ball mill; 4. Vibrating screen assembly; 5. Online laser particle size analyzer; 6. Bucket elevator; 7. Diverter valve; 8. Finished product discharge silo; 9. PLC automatic control unit; 10. Data acquisition and display terminal. Detailed Implementation
[0030] To make the technical problems to be solved, the technical solutions, and the beneficial effects of the present invention clearer, the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention.
[0031] like Figure 1-2 As shown, an automatic detection and control device for particle size distribution of solid waste powder is characterized by comprising: The multi-compartment metering and feeding unit includes at least three independent solid waste storage silos 1. Each silo is equipped with a variable frequency metering screw feeder at its bottom, which is used to simultaneously transport various solid waste raw materials to a connected collection buffer hopper 2 below for mixing according to a preset mass ratio. Specifically, the three independent solid waste storage silos 1 are labeled A, B, and C and contain different solid waste raw materials. The silo walls are made of stainless steel, which has good wear resistance and corrosion resistance. The mass feeding rate (kg / h) of each solid waste raw material is precisely controlled by adjusting the speed of the variable frequency metering screw feeder, so as to realize the metering ratio and coordinated feeding of multi-source solid waste. The collection buffer hopper 2 collects the discharge from the screw feeders of each silo and serves as a mixing buffer node for various solid waste powders, so as to perform preliminary mixing and homogenization of multi-source solid waste with different particle sizes and densities. An airlock discharge valve is installed at the bottom of the collection buffer hopper to prevent dust from overflowing and to realize quantitative downstream conveying.
[0032] The mechanical ball mill grinding unit includes a frequency converter-driven ball mill 3, the feed inlet of which is connected to the discharge outlet of the collection buffer hopper 2, for grinding mixed solid waste. The vibrating screen grading unit includes at least two stacked vibrating screen assemblies 4. The feed end of the vibrating screen assembly 4 is connected to the discharge port of the ball mill 3, and is used to classify the ground products according to particle size in a stepwise manner. The online laser particle size detection unit includes an online laser particle size analyzer 5, the sample inlet of which is connected to the fine particle outlet of the vibrating screen assembly 4, for real-time measurement of particle size distribution data of powder samples. The closed-loop circulation pipeline unit includes a bucket elevator 6 and a pneumatic diversion valve 7. The feed end of the bucket elevator 6 is connected to the coarse particle discharge port of the vibrating screen assembly 4 and the first discharge port of the diversion valve 7. The discharge end of the bucket elevator 6 is connected to the feed port of the ball mill 3. The feed port of the diversion valve 7 is connected to the discharge end of the online laser particle size analyzer 5, and the second discharge port of the diversion valve 7 is connected to the finished product discharge silo 8. Specifically, the finished product discharge silo 8 is used to store qualified solid waste powder that meets the target particle size distribution requirements. A pneumatic airlock discharge valve is installed at the bottom of the silo, which can discharge materials in batches and quantities for use in the preparation of downstream solid waste cementitious materials. A pulse-type bag filter is installed at the top of the silo to effectively prevent dust from escaping. When the bucket elevator 6 is working, it lifts the coarse particles on the vibrating screen from the bottom hopper to the top of the ball mill 3. The conveying capacity and lifting height are configured according to the system scale.
[0033] The PLC automatic control unit 9 is electrically connected to the variable frequency metering screw feeder, the frequency converter of the ball mill 3, the excitation motor of the vibrating screen assembly 4, the online laser particle size analyzer 5, and the diversion valve 7. The PLC automatic control unit 9 has a built-in particle size distribution target curve database, which is used to receive the particle size distribution data measured in real time by the online laser particle size analyzer 5, compare the collected particle size distribution data with the target gradation curve, and automatically adjust the rotation speed of the ball mill 3, the excitation parameters of the vibrating screen assembly 4, and the on / off state of the diversion valve 7 according to the comparison results, forming a closed-loop control loop for online particle size detection and automatic grinding control. The data acquisition and display terminal 10 is connected to the PLC automatic control unit 9 in communication. It is used to display the comparison chart of particle size distribution data and target gradation curve in real time, and to record the process parameters of the whole process simultaneously.
[0034] Specifically, the PLC automatic control unit 9 has a built-in particle size distribution target curve database that pre-stores standard particle size distribution curves calculated based on the Fuller equation and / or Andreasen equation. The PLC automatic control unit 9 uses a D50 deviation ≤ 5% and a D90 deviation ≤ 8% as the particle size qualification threshold. The PLC automatic control unit 9 preferentially uses an industrial-grade PLC host (CPU module + I / O expansion module) to execute a fully automatic closed-loop control logic of "detection → comparison → judgment → adjustment." It connects to relevant equipment through electrical interfaces to achieve centralized control and status monitoring of all electrical equipment in the device. Specifically, deviation = |measured value - target value| / target value × 100%. For example, if the D50 target is set to 15μm and the current value is 14.25μm, the deviation is |14.25 - 15| / 15 × 100% = 5%.
[0035] Specifically, the vibrating screen assembly 4 includes an upper screen and a lower screen stacked on top of each other. The upper screen has a mesh size of 200, and the lower screen has a mesh size of 400, achieving step-size particle size classification of the milled product. The coarse particles intercepted by the upper screen are returned to the ball mill 3 via the bucket elevator 6, while the fine particles screened by the lower screen are sent to the online laser particle size analyzer 5 via a pneumatic conveying pipeline. During operation, the excitation frequency and amplitude of the vibrating screen assembly 4 are adjustable and controlled by the PLC automatic control unit 9.
[0036] Specifically, the ball mill 3 is the core grinding execution unit of the device. Its cylinder is filled with three different sizes of grinding media, namely large (Φ50mm), medium (Φ30mm), and small (Φ15mm), designed according to gradation. Grinding steel balls are preferred to achieve efficient graded grinding. The main motor of the ball mill 3 is equipped with a variable frequency speed control device. The speed adjustment range of the variable frequency speed control device is 40%-100% of the rated speed. During operation, the ball mill 3 is automatically adjusted in real time by the PLC control unit to adapt to the grinding requirements of different target particle sizes.
[0037] Specifically, the online laser particle size analyzer 5 employs the dynamic light scattering principle or the laser diffraction principle. The sample inlet is connected to the fine particle outlet of the vibrating screen assembly 4 via a sealed pipeline. It has a built-in dry dispersion system, with a single measurement cycle not exceeding 60 seconds. The online laser particle size analyzer 5 is connected to the PLC automatic control unit 9 via an RS485 digital signal interface, with a data transmission delay not exceeding 1 second. When the online laser particle size analyzer 5 is working, it preferably measures characteristic particle sizes D10, D50, and D90. After obtaining a complete particle size distribution curve, the data is transmitted in real-time to the PLC automatic control unit 9 via the RS485 digital signal interface and stored for later use.
[0038] Specifically, the pneumatic diversion valve 7 is a three-way diversion valve, and the switching response time of the pneumatic diversion valve 7 is less than 0.5 seconds; when the PLC automatic control unit 9 determines that the current particle size has not reached the target gradation, the diversion valve 7 is connected to the return grinding channel of the ball mill 3 feed inlet; when it is determined that the particle size meets the target gradation, the diversion valve 7 is switched to the direction of the finished product discharge bin 8.
[0039] Specifically, the data acquisition and display terminal 10 is equipped with an industrial-grade waterproof touchscreen. All process parameters are stored in a local database in timestamp format, supporting historical data queries, comparative analysis, and export of data in CSV / Excel format by time or batch. Specifically, the data acquisition and display terminal 10 is preferably equipped with a 15-inch industrial-grade waterproof touchscreen, integrating an HMI operating interface and data management functions; it displays in real-time particle size distribution curves (D10, D50, D90 dynamic trend charts), feed rates in each bin, ball mill speed and current, vibrating screen parameters, and system operating status.
[0040] An automatic detection and control method for particle size distribution of solid waste powder, applied to the device described above, includes the following steps: Step 1, Feeding and Mixing: Through the multi-compartment metering feeding unit, at least three solid waste raw materials are simultaneously metered and transported to the collection buffer hopper 2 for mixing according to the preset mass ratio; Step 2, grinding: The mixed solid waste raw materials are fed into the variable frequency ball mill 3 for grinding; Step 3, Classification: The milled product is fed into at least two stacked vibrating screen components 4 and classified in a step-by-step manner according to particle size to obtain coarse and fine particles. Step 4, online detection: The graded fine particles are continuously fed into the online laser particle size analyzer 5 to measure the particle size distribution data of the fine particles in real time, including the characteristic particle sizes of D10, D50, and D90 and the complete particle size distribution curve. Step 5, closed-loop control: The PLC automatic control unit 9 receives real-time particle size distribution data, compares the real-time particle size distribution data with the built-in target gradation curve, and controls the diversion valve 7 to re-grind the coarse particles and collect and output the qualified powder. Step 6, Data Recording: The comparison chart between the particle size distribution curve and the target gradation curve is displayed in real time throughout the entire process, and all process parameters are recorded in timestamp format.
[0041] The closed-loop control in step five includes: when the particle size distribution does not reach the target gradation, the PLC automatic control unit 9 adjusts the rotation speed of the ball mill 3 and / or the excitation parameters of the vibrating screen assembly 4, and controls the diversion valve 7 to open the return grinding channel, so that the bucket elevator 6 returns the coarse particles to the ball mill 3 for further grinding. When the particle size distribution reaches the target gradation, the PLC automatic control unit 9 controls the diversion valve 7 to switch to the finished product discharge channel, collecting the qualified powder into the finished product discharge hopper 8. Specifically, the excitation parameter mainly refers to the excitation frequency.
[0042] In one specific embodiment, the operation method is as follows: Phase 1: Device initialization and target gradation parameter setting Before formally conducting the solid waste powder particle size distribution control experiment, first access the system main interface through the data acquisition and display terminal 10, and perform device initialization and parameter settings according to the following steps: (1) Raw material loading: The solid waste raw materials to be processed (such as fly ash, coal gangue, steel slag, etc.) are loaded into the corresponding solid waste storage bins 1 respectively. According to the design scheme of the whole solid waste cementitious material, the feeding rate (kg / h) of the screw feeder of each bin is set on the touch screen to ensure that the mass ratio of each solid waste raw material entering the collection buffer hopper 2 meets the design requirements (e.g., fly ash 40%, slag 30%, steel slag 20%, desulfurization gypsum 10%).
[0043] (2) Target gradation selection: Enter the "Target Graination Setting" function module on the touch screen, select the applicable target gradation standard from the PLC's built-in gradation curve database (such as the standard dense gradation curve with Fuller index n=0.45), or manually input the target D10, D50, and D90 values as needed for the research (e.g., D10=3μm, D50=15μm, D90=45μm). The system will automatically generate the corresponding target gradation curve and store it as the target parameters for this batch.
[0044] (3) Deviation Judgment Threshold Setting: Set the particle size qualification judgment threshold in the "Qualification Judgment Parameter" interface (default is D50 deviation ≤ 5%, D90 deviation ≤ 8%), which can also be tightened or loosened appropriately according to the experimental accuracy requirements. After confirming that there are no errors, click the "System Self-Test" button. The PLC will automatically check the communication status of each electrical device (frequency converter, laser particle size analyzer, pneumatic valve, sensor) in sequence. After the self-test is passed, the system enters the standby state, and the data acquisition of the whole process will start automatically.
[0045] Phase 2: Co-feeding and grinding of multiple solid wastes
[0046] After clicking the "Start Run" button on the touchscreen, the PLC starts each device sequentially according to the preset logic, entering the formal operation phase: 1) Co-feeding: The variable frequency metering screw feeders at the bottom of each solid waste storage bin 1 start synchronously at the set speed, continuously conveying the solid waste raw materials from each source to the collection buffer hopper 2 according to the designed ratio; while receiving multiple solid waste feeds, the collection buffer hopper achieves the initial homogenization of various solid waste particles through the initial mixing effect of its own cavity, laying the foundation for the co-processing of the subsequent grinding process.
[0047] 2) Ball Mill Grinding: The bottom discharge valve of the collection buffer hopper 2 is opened, and the mixed solid waste material enters the variable frequency ball mill 3. The ball mill operates at the speed initially set by the PLC (usually 75%-85% of the rated speed). The three-stage grinding steel balls inside the cylinder work together to impact and grind the solid waste particles, achieving preliminary particle size refinement. The grinding product enters the vibrating screen assembly 4 through the discharge port for particle size classification.
[0048] 3) Vibrating Screening: The excitation motor of the vibrating screening component 4 operates at a set frequency and amplitude. The grinding product is classified in a step-by-step manner on the double-layer screen according to the particle size: the coarse particles with a particle size greater than 75μm (the material on the upper screen) fall into the bottom of the bucket elevator 6 through the left return pipe and wait to be lifted and returned to the mill; the fine particles with a particle size less than 38μm are quantitatively sent to the online laser particle size analyzer 5 through the pneumatic conveying pipeline for real-time particle size detection.
[0049] Phase 3: Online Particle Size Detection and PLC Closed-Loop Control
[0050] The online laser particle size analyzer 5 continuously samples and measures the particle size distribution of fine solid waste powder entering the analysis chamber. 1) Real-time particle size determination: After the sample is uniformly dispersed by the built-in dry dispersion module, the particle size distribution curve of the sample is determined by laser diffraction, and the characteristic particle size values such as D10, D50, and D90 are automatically calculated. After the determination is completed, the particle size data is transmitted in real time to the PLC automatic control unit 9 in digital signal format via RS485 interface, with a transmission delay of no more than 1 second. The data acquisition and display terminal 10 synchronously displays a superimposed comparison diagram of the real-time particle size distribution curve and the target gradation curve, allowing researchers to intuitively observe the gradation control process.
[0051] 2) PLC Deviation Judgment and Automatic Control: After receiving the particle size measurement data, the PLC automatic control unit 9 calculates the deviation between the current particle size distribution and the target gradation curve in real time (using D50 and D90 deviations as the main criteria). If the deviation exceeds the preset threshold (i.e., the particle size is too coarse and grinding needs to continue), the PLC performs the following control operations: ① Outputs a frequency increase command to the ball mill frequency converter to increase the mill speed by 3%-8% (which can be linearly adjusted within the range of 3%-8% according to the deviation size to increase the grinding intensity); ② The pneumatic diversion valve (7) keeps the return grinding channel open, so that the bucket elevator 6 sends the coarse material back to the ball mill feed port for another grinding cycle; ③ After each detection-control cycle is completed, the PLC synchronously uploads the current particle size data, control command and timestamp to the data acquisition terminal 10 for real-time recording. The above closed-loop control process of "detection → comparison → adjustment → re-detection" is continuously and automatically executed without manual intervention.
[0052] 3) Targeted collection of qualified materials: When the online particle size detection results show that the current particle size distribution meets the target gradation curve (D50 deviation ≤ 5%, D90 deviation ≤ 8%), the PLC determines that the batch of materials is qualified and immediately issues the following instructions: ① The pneumatic diversion valve 7 is switched to the direction of the finished product discharge bin 8; ② The ball mill speed is maintained at the current stable operation; ③ The top material of the bucket elevator (6) is introduced into the finished product discharge bin 8 through the diversion valve to complete the targeted collection and storage of qualified materials.
[0053] Phase 4: Experiment Completion and Data Processing
[0054] Once the preset experimental amount of solid waste powder has been processed (the feed rate is monitored by the feed level sensor in the feed hopper), the PLC automatically triggers the shutdown process, and each driven device stops in sequence (first the feed is stopped, then the ball mill is stopped, and finally the vibrating screen and laser instrument are stopped) to ensure that all residual materials in the system are sorted and processed before safely shutting down.
[0055] After the experiment, the researchers accessed the "Data Management" module through the data acquisition and display terminal 10, retrieved the entire process record data of this batch (particle size evolution curve, time series of operating parameters of each equipment, and feed statistics), conducted a systematic analysis of process parameters and control effects, and exported the data in CSV or Excel format, providing an experimentally verified particle size control data basis for the compatibility optimization design of the whole solid waste coagulation system.
[0056] It should be noted that, in this document, relational terms such as "first" and "second" are used only to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus.
[0057] The embodiments described above are merely preferred embodiments of the present invention and are not intended to limit the scope of the present invention. Various modifications and improvements made by those skilled in the art to the technical solutions of the present invention without departing from the spirit of the present invention should fall within the protection scope defined by the claims of the present invention.
Claims
1. An automatic detection and control device for particle size distribution of solid waste powder, characterized in that, include: The multi-compartment metering feeding unit includes at least three independent solid waste storage silos (1), and each storage silo is equipped with a variable frequency metering screw feeder at the bottom, which is used to simultaneously transport multiple solid waste raw materials to the collection buffer hopper (2) connected below for mixing according to a preset mass ratio; The mechanical ball mill grinding unit includes a variable frequency drive ball mill (3), the feed inlet of which is connected to the discharge outlet of the collection buffer hopper (2), and is used to grind mixed solid waste. The vibrating screen grading unit includes at least two stacked vibrating screen assemblies (4), the feed end of which is connected to the discharge port of the ball mill (3), and is used to classify the grinding products according to particle size in a stepwise manner. The online laser particle size detection unit includes an online laser particle size analyzer (5), the sample inlet of which is connected to the fine particle outlet of the vibrating screen assembly (4), and is used to measure the particle size distribution data of the powder sample in real time. The closed-loop circulation pipeline unit includes a bucket elevator (6) and a pneumatic diversion valve (7). The feed end of the bucket elevator (6) is connected to the coarse particle discharge port of the vibrating screen assembly (4) and the first discharge port of the diversion valve (7). The discharge end of the bucket elevator (6) is connected to the feed port of the ball mill (3). The feed port of the diversion valve (7) is connected to the discharge end of the online laser particle size analyzer (5). The second discharge port of the diversion valve (7) is connected to the finished product discharge silo (8). The PLC automatic control unit (9) is electrically connected to the variable frequency metering screw feeder, the frequency converter of the ball mill (3), the excitation motor of the vibrating screen assembly (4), the online laser particle size analyzer (5), and the diversion valve (7), respectively. The PLC automatic control unit (9) has a built-in particle size distribution target curve database, which is used to receive the particle size distribution data measured in real time by the online laser particle size analyzer (5), compare the collected particle size distribution data with the target gradation curve, and automatically adjust the rotation speed of the ball mill (3), the excitation parameters of the vibrating screen assembly (4), and the on / off state of the diversion valve (7) according to the comparison results, forming a closed-loop control loop for online particle size detection and automatic grinding control. The data acquisition and display terminal (10) is connected to the PLC automatic control unit (9) in communication. It is used to display the comparison diagram of particle size distribution data and target gradation curve in real time, and to record the process parameters of the whole process in a synchronous manner.
2. The automatic detection and control device for particle size distribution of solid waste powder according to claim 1, characterized in that: The PLC automatic control unit (9) has a built-in target particle size distribution curve database that pre-stores standard particle size distribution curves calculated based on the Fuller equation and / or the Andreasen equation; the PLC automatic control unit (9) uses D50 deviation ≤ 5% and D90 deviation ≤ 8% as the particle size qualification threshold.
3. The automatic detection and control device for particle size distribution of solid waste powder according to claim 1, characterized in that: The vibrating screen assembly (4) includes an upper screen and a lower screen stacked on top of each other. The mesh size of the upper screen is set to 200 mesh, and the mesh size of the lower screen is set to 400 mesh. The coarse particles intercepted by the upper screen are returned to the ball mill (3) via the bucket elevator (6), and the fine particles screened by the lower screen are sent to the online laser particle size analyzer (5) via a pneumatic conveying pipeline.
4. The automatic detection and control device for particle size distribution of solid waste powder according to claim 1, characterized in that: The ball mill (3) is filled with grinding media of three different sizes, large, medium and small, designed according to gradation; the main motor of the ball mill (3) is equipped with a variable frequency speed control device, and the speed adjustment range of the variable frequency speed control device is 40% to 100% of the rated speed.
5. The automatic detection and control device for particle size distribution of solid waste powder according to claim 1, characterized in that: The online laser particle size analyzer (5) adopts the dynamic light scattering principle or the laser diffraction principle, and has a built-in dry dispersion system. The single measurement cycle does not exceed 60 seconds. The online laser particle size analyzer (5) is connected to the PLC automatic control unit (9) through the RS485 digital signal interface, and the data transmission delay does not exceed 1 second.
6. The automatic detection and control device for particle size distribution of solid waste powder according to claim 1, characterized in that: The pneumatic diverter valve (7) is a three-way diverter valve, and the switching response time of the pneumatic diverter valve (7) is less than 0.5 seconds. When the PLC automatic control unit (9) determines that the current particle size does not meet the target gradation, the diverter valve (7) is connected to the return grinding channel of the feed inlet of the ball mill (3). When it is determined that the particle size meets the target gradation, the diverter valve (7) is switched to the direction of the finished product discharge bin (8).
7. The automatic detection and control device for particle size distribution of solid waste powder according to claim 1, characterized in that: The data acquisition and display terminal (10) is equipped with an industrial-grade waterproof touch screen. All process parameters are stored in the local database in timestamp format. It supports historical data query, comparison analysis and export of CSV / Excel format data by time or batch.
8. An automatic detection and control method for particle size distribution of solid waste powder, applied to the apparatus described in any one of claims 1 to 7, characterized in that, Includes the following steps: Step 1, feeding and mixing: Through the multi-compartment metering feeding unit, at least three solid waste raw materials are simultaneously metered and transported to the collection buffer hopper (2) for mixing according to the preset mass ratio; Step 2, grinding: The mixed solid waste raw materials are fed into a variable frequency ball mill (3) for grinding; Step 3, Classification: The milled product is fed into at least two stacked vibrating screen components (4) and classified in a stepwise manner according to particle size to obtain coarse and fine particles. Step 4, online detection: The graded fine particles are continuously fed into an online laser particle size analyzer (5) to measure the particle size distribution data of the fine particles in real time, including the characteristic particle sizes of D10, D50, and D90 and the complete particle size distribution curve. Step 5, closed-loop control: The PLC automatic control unit (9) receives real-time particle size distribution data, compares the real-time particle size distribution data with the built-in target gradation curve, and controls the diversion valve (7) to re-grind the coarse particles and collect and output the qualified powder. Step 6, Data Recording: The comparison chart between the particle size distribution curve and the target gradation curve is displayed in real time throughout the entire process, and all process parameters are recorded in timestamp format.
9. The automatic detection and control method for particle size distribution of solid waste powder according to claim 8, characterized in that: The closed-loop control in step five includes: when the particle size distribution does not reach the target gradation, the PLC automatic control unit (9) adjusts the rotation speed of the ball mill (3) and / or the excitation parameters of the vibrating screen assembly (4), and controls the diversion valve (7) to open the return grinding channel, and the bucket elevator (6) returns the coarse particles to the ball mill (3) for grinding again. When the particle size distribution reaches the target gradation, the PLC automatic control unit (9) controls the diversion valve (7) to switch to the finished product discharge channel and collect the qualified powder into the finished product discharge hopper (8).