Coal and gangue sorting device based on horizontal particle size distribution and terahertz linear frequency modulation

Abstract

The invention discloses a coal and gangue sorting device based on horizontal particle size distribution and terahertz linear frequency modulation, and belongs to the field of coal and gangue sorting. The device comprises a crusher, a sorting conveying roller, a conveying belt, a crusher bottom guide plate, a discharge tail end guide plate and an information processing system, the information processing system comprises a microprocessor, and the microprocessor is connected with a terahertz signal transmitting device, a terahertz signal receiving and processing device, a pressure sensor, a motor and a high-precision angle sensor. Two groups of sorting conveying rollers are arranged below the crusher; three groups of terahertz signal transmitting devices and terahertz signal receiving and processing devices are respectively arranged above a conveying belt; and three groups of discharging tail end guide plates with different sizes are arranged at the tail end of the conveying belt, and coal gangue and coal with different particle sizes are sorted out under the control of an information processing system. The device can complete granularity sorting in the horizontal direction; and a terahertz wave linear frequency modulation analysis technology is used to associate and optimize each operation unit, so that the underground coal mine modular compact efficient sorting system is constructed.

Description

Technical Field

[0001] The invention relates to a coal gangue separation device based on horizontal particle size classification and terahertz linear frequency modulation, belonging to the technical field of coal gangue separation. Background Art

[0002] During coal mining, effective sorting of gangue is crucial for improving coal quality and resource utilization. However, in some existing sorting systems (such as Chinese patent CN114535063A), the particle size sorting method often suffers from irrational space utilization and low efficiency. In addition, the physical properties of gangue vary greatly, and gangue of different particle sizes differ in shape, density, porosity, etc., which poses a higher challenge to sorting technology. For example, large-particle gangue may have a more regular shape, a higher density, and a relatively lower porosity; while small-particle gangue may have an irregular shape, a lower density, and a higher porosity. These physical properties can significantly affect the identification and separation effect of sorting technology on gangue. Therefore, there is a need for an innovative gangue sorting device and method that can fully consider the differences in the physical properties of gangue and improve the accuracy and efficiency of sorting. Summary of the Invention

[0003] In response to the problems existing in the prior art, the present invention provides a coal gangue sorting device based on horizontal particle size classification and terahertz linear frequency modulation. This device breaks through the inherent concept of traditional stacked arrangement and realizes the function of completing particle size sorting in the horizontal direction. At the same time, it uses the new terahertz wave linear frequency modulation analysis technology to optimize the relationship between each operating unit in the process flow in the time and space dimensions, and constructs a modular, compact and efficient sorting system for underground coal mines.

[0004] The present invention primarily achieves horizontal particle size separation of coal gangue through a crusher and an adjustable roller assembly. Terahertz linear frequency modulation technology is used to transmit and process signals, which are then received, filtered, and mixed before being analyzed by a control device. Coal and gangue are identified based on differences in the dielectric constants of the gangue, with each component working in concert to complete the separation process. The gangue separation device provided by the present invention also has the ability to distribute gangue during the separation process. It can effectively increase the spacing between materials while significantly reducing the probability of material overlap. It can also achieve three particle size separations in the horizontal direction. This not only facilitates equipment installation and replacement, creates extremely favorable conditions for subsequent identification operations, greatly improves the accuracy of system identification, but also further enhances the efficiency and reliability of the entire separation process, effectively promoting the innovation and development of working face separation technology.

[0005] The present invention provides a coal gangue sorting device based on horizontal particle size classification and terahertz linear frequency modulation, comprising a crusher, a sorting conveyor roller, a conveyor belt, a guide plate, and an information processing system; the information processing system comprises a microprocessor located below the conveyor belt, and the microprocessor is respectively connected to a terahertz signal transmitting device, a terahertz signal receiving and processing device, a pressure sensor, a motor, and a high-precision angle sensor;

[0006] A discharge port is provided at the bottom of the crusher, and an adjustable angle guide plate is provided at the discharge port of the crusher. The opening and closing angle of the guide plate is controlled by the information processing system;

[0007] Two sets of sorting rollers are located beneath the crusher. These rollers are parallel and tilted at an angle of 15° to 45° to the ground. They rotate continuously, controlled by a motor. Automatically opening and closing paddles are located on one side of the rollers. A conveyor belt is located beneath the sorting rollers. A partition is installed in the middle of the conveyor belt, dividing it into three sections, each separated by a partition.

[0008] Two rows of brackets are arranged parallel to each other above the conveyor belt. A terahertz signal transmitter and a terahertz signal receiver are installed on top of the brackets. A terahertz signal receiver is installed behind the terahertz signal transmitter. The terahertz signal receiver includes a signal receiver, a filter, and a mixer. The terahertz signal receiver is connected to the filter, which is directly connected to the mixer. The terahertz signal receiver is at the same height as the terahertz signal transmitter.

[0009] The sorting and conveying rollers are composed of an upper roller group and a lower roller group arranged in parallel. The gaps between the rollers in the upper roller group are smaller, while the gaps between the rollers in the lower roller group are larger. The gaps between each roller group can be adjusted according to the desired particle size by rotating a motor mounted on a bracket. A pressure sensor is installed inside the sorting and conveying rollers. This pressure sensor is connected to a microprocessor and is responsible for monitoring the flow of coal gangue and converting it into an electrical signal for transmission to the microprocessor. The microprocessor analyzes the signal according to a preset program. When the pressure sensor signal exceeds a set high threshold, indicating a high flow of coal gangue, the microprocessor drives the adjustment device to reduce the opening and closing angle of the guide plate, allowing the coal gangue to fall dispersedly onto the roller group. When the signal falls below a set low threshold, indicating a low flow of coal gangue, the microprocessor increases the angle of the guide plate to ensure smooth sliding of the coal gangue.

[0010] The automatic opening and closing mechanism of the paddles is associated with the pressure sensor inside the roller group. When the coal gangue is blocked and the pressure inside the roller reaches the preset upper limit, the pressure sensor sends a signal to the microprocessor, which controls the paddles to pop out and clear the blockage. After the material is cleared, the pressure drops to the lower limit, and the pressure sensor feeds back a signal to the microprocessor, which controls the paddles to return to their original position to ensure stable operation of the roller group.

[0011] At the tail end of the conveyor belt, three sets of discharge end guide plates of varying sizes are installed. These are controlled by the information processing system to separate gangue and coal of varying particle sizes. A terahertz signal transmitter emits a terahertz signal, which is reflected by the gangue. A terahertz signal receiver and processor receives the reflected signal, where a filter removes noise and interference. A mixer mixes the received terahertz signal with the local oscillator signal according to a specific formula, generating a difference frequency signal that is transmitted to the information processing system. The information processing system's communication interface receives this difference frequency signal and transmits it to a microprocessor, which analyzes the signal based on a pre-set algorithm stored in a storage unit to identify coal and gangue.

[0012] When the microprocessor detects that the gangue has reached the guide plate at the end of the discharge, it controls the crank to move rapidly, causing the guide plate to tilt. During this process, a high-precision angle sensor closely tracks the plate's tilting progress and feeds real-time angle data back to the microprocessor. Based on this feedback, the microprocessor precisely adjusts the crank's extension and extension angle, ensuring that the guide plate reaches the preset tilt angle with extremely high accuracy.

[0013] As a further optimization solution of the present invention: a drying device is installed on the bracket close to the sorting conveying roller.

[0014] As a further optimization solution of the present invention: a manual control valve is provided on the side of the crusher, and the opening and closing of the guide plate are manually adjusted when the crusher is shut down for maintenance.

[0015] As a further optimization scheme of the present invention: a main roller is provided in the middle portion below the upper and lower roller groups, and the main roller is connected to a motor, which drives the main roller to rotate; the main roller is connected to the intermediate rollers of the upper and lower roller groups and can rotate relative to each other; adjacent rollers are connected by a belt, and driven by the motor, the intermediate rollers of the upper and lower roller groups rotate, thereby driving the remaining rollers to rotate. Specifically, the motor drives the main roller to rotate; the main roller is connected to the intermediate roller of the upper and lower roller groups respectively by belts, and the upper and lower intermediate rollers are powered by the main roller, driving the intermediate rollers to rotate (relying on the friction between the rollers and the belt to cause the belt to circulate); the remaining adjacent rollers are connected by belts, and driven by the intermediate rollers and the belt, the friction between the rollers and the belt causes the belt to circulate, and the passive roller passively rotates by the friction with the belt, without the need for independent power.

[0016] As a further optimization scheme of the present invention: three terahertz linear frequency modulation signal transmitters are respectively set corresponding to the three conveyor belts, and the frequency range of the linear frequency modulation signal emitted by the terahertz linear frequency modulation signal transmitter only includes the minimum and maximum frequencies required by coal gangue of different particle sizes; among them, the frequency corresponding to the small particle size is 3-5THz, the frequency corresponding to the medium particle size is 1-3THz, and the frequency corresponding to the large particle size is 0.5-1THz.

[0017] As a further optimization of the present invention, the three filters used for terahertz signal processing are placed within a shielding box in the device design. Made of materials with excellent electromagnetic shielding properties, this shielding box effectively blocks the effects of external electromagnetic interference signals on the filters, ensuring that the filters maintain stable and efficient operation during terahertz signal processing. This, in turn, safeguards the signal processing accuracy and reliability of the entire coal gangue sorting device, enabling smooth coal gangue identification and sorting operations based on terahertz linear frequency modulation technology.

[0018] As a further solution of the present invention, determining the position and category of the current target using data obtained from the terahertz linear frequency modulation signal specifically includes:

[0019] First, the signal transmitter transmits a linear frequency modulated terahertz signal. The transmitted signal is:

[0020]

[0021] Where S T Indicates the transmission signal, A T is the amplitude of the transmitted signal, f0 is the starting frequency, K is the frequency modulation slope, t is the time, and the imaginary unit j is the sine or cosine signal.

[0022] After being reflected by the coal gangue to be measured, the transmitted signal is mixed with the echo signal to obtain the difference frequency signal. The difference frequency signal formula is:

[0023]

[0024] Where A is the signal amplitude; f0 is the starting frequency; K is the frequency modulation slope (which is the ratio of the signal bandwidth B to the period T); is the delay between the transmitted signal and the echo signal, R is the distance to the object to be measured, C = 3 × 10 8 m / s is the speed of electromagnetic waves in a vacuum.

[0025] In the actual calculation process, due to The term is very small and can be ignored. Substitute it into Kτ and the frequency of the difference frequency signal is The difference frequency is determined by fast Fourier transform, and the peak value f of the obtained amplitude-frequency curve is IFmax Corresponds to the position of the target.

[0026] The relationship between distance resolution and bandwidth in air is:

[0027] Where B represents the signal bandwidth.

[0028] In a medium with a dielectric constant of ε, the formula for the propagation speed of electromagnetic waves in the medium is Where v is the propagation speed of electromagnetic waves in the medium. Since the distance resolution is related to the propagation speed of electromagnetic waves, the distance resolution becomes

[0029] When m coal gangue mixtures pass through the test area, there will be m reflected echoes, and the corresponding amplitude-frequency curve will also have m peaks f IFmax , in order to obtain information at different depths of coal gangue and achieve the resolution of multiple interfaces. The distance between any two peaks is the electrical thickness of the layer of medium: i = 1, 2, ..., m; when m coal-gangue mixtures pass through the test area, there will be m reflected echoes, and correspondingly, the amplitude-frequency curve will also have m peaks; each peak formed by the reflected echo on the amplitude-frequency curve has a corresponding number, and i (1 to m) represents these numbers, that is, the number of the coal-gangue mixture; the information processing system can then analyze and process different peaks separately to obtain information at different depths of the coal-gangue; C represents the propagation speed of electromagnetic waves in a vacuum, C = 3×10 8 m / s.

[0030] The relationship between gangue thickness, electrical thickness and dielectric constant is as follows:

[0031] Assume that the frequency of the transmitted linear frequency modulation signal is f(t)=f0+Kt;

[0032] Where f0 is the starting frequency, K is the frequency modulation slope, and t is the time.

[0033] When the signal penetrates the coal gangue, the received signal will produce a time delay, that is, the delay τ between the above signal and the echo signal. According to the formula The thickness of coal gangue can be calculated.

[0034] In summary, the dielectric constant of the coal gangue to be measured is calculated based on the thickness and electrical thickness of the coal gangue. Coal and gangue can be identified based on the difference in dielectric constants.

[0035] As a further solution of the present invention: the three groups of discharge end guide plates are installed on the fixed frame at the tail end of the conveyor belt, and the width of the fixed frame is the same as the width of the conveyor belt; the three groups of discharge end guide plates are spatially slightly lower than the horizontal plane of the conveyor belt. The fixed frame and the discharge end guide plates are connected by a crank. A crank is provided at the bottom of the discharge end guide plates. The crank is connected to a high-precision angle sensor. The high-precision angle sensor is provided on the fixed frame and connected to a microprocessor. The three groups of discharge end guide plates are horizontally and tilted by an information processing system. When the material slides to the discharge end guide plates, the information processing system will send a command to the crank to tilt the discharge end guide plates downward by 30° to 60°, so that the gangue falls into the gangue transfer assembly and is transported to the goaf, while the coal continues to be transported along the conveyor belt to the subsequent processing area.

[0036] The present invention provides a method for sorting coal gangue using the above-mentioned coal gangue sorting device based on horizontal particle size classification and terahertz linear frequency modulation, comprising the following steps:

[0037] (1) After the material enters the crusher and is crushed, it falls onto the roller group through the guide plate at the bottom of the crusher and then slides downward under the action of gravity. Small-sized materials fall onto the conveyor belt below through the gap between the upper roller group, medium-sized materials fall onto the conveyor belt below through the gap between the lower roller group, and large-sized materials slide directly onto the conveyor belt; that is, materials of different particle sizes fall onto conveyor belts separated by partitions.

[0038] (2) The coal gangue mixture divided into three particle sizes is transmitted through a terahertz linear frequency modulation signal by a transmitting device, and then the terahertz linear frequency modulation signal reflected by the coal gangue is received by a receiving device, and is de-noised by a connected filter, and then transmitted to a mixer connected to the filter, and the mixer mixes the received terahertz signal with a local oscillator signal, and finally transmitted to an information processing system for processing;

[0039] (3) When the gangue slides to the guide plate at the end of the discharge, the information processing system will issue a command to control the guide plate at the end of the discharge to tilt downward by 30° to 60°. When the information processing system detects that the gangue has reached the guide plate at the end of the discharge, it will immediately send a precise control command to the crank. Driven by the command, the crank moves quickly, pushing the guide plate at the end of the discharge to begin tilting. During this process, the high-precision angle sensor closely tracks the tilting process of the guide plate at the end of the discharge and feeds back the real-time angle data to the information processing system. The information processing system accurately adjusts the extension and contraction range and angle of the crank based on a large amount of feedback data, ensuring that the guide plate at the end of the sorting discharge can reach the preset tilt angle with extremely high precision.

[0040] Beneficial effects of the present invention:

[0041] (1) The guide plate at the crusher discharge port can be freely adjusted to change the coal gangue flow rate according to actual needs.

[0042] (2) The parallel conveyor roller assembly used for particle size separation not only achieves horizontal particle size separation, but also disperses the density of coal gangue materials on the conveyor belt, achieving intermittent drop and reducing overlap. In addition, the built-in sensor and the automatically opening and closing paddle device effectively solve the problem of possible blockage. In addition, the gap between the rollers can be adjusted according to actual needs, which is highly flexible.

[0043] (3) A drying device is installed in the particle size sorting device, which effectively solves the impact of moisture on subsequent identification.

[0044] (4) The sorting conveyor rollers are connected by belts for rotation. Only one of the conveyor rollers needs to be connected to the power supply, and the other conveyor rollers can rotate synchronously with the help of belt drive. This design greatly simplifies the power configuration, ensuring the stable operation of the conveying function while significantly improving the convenience of the equipment. The installation process is simple and efficient, without the need for complicated line laying and debugging; it is also easy to disassemble, effectively reducing the difficulty and time cost of equipment maintenance and component replacement, and greatly enhancing the overall practicality and operability of the equipment.

[0045] (5) Terahertz linear frequency modulation technology is used in the identification device. The characteristic of the signal frequency changing over time allows the system to use the frequency change information to improve the target resolution ability and obtain more dimensional information through frequency modulation. In addition, the energy distribution and propagation characteristics of linear frequency modulation terahertz waves are more stable when penetrating coal and gangue, and the reliability and stability of the system are also improved.

[0046] (6) The information processing system works in conjunction with the crank and angle sensor to accurately control the inclination angle of the guide plate at the end of the discharge, ensuring that the gangue accurately falls into the transfer assembly and is transported to the goaf, and the coal smoothly enters the subsequent processing link, making the entire coal and gangue sorting process efficient and orderly, effectively improving the accuracy and efficiency of sorting. BRIEF DESCRIPTION OF THE DRAWINGS

[0047] Figure 1 It is a schematic diagram of the overall structure of the present invention;

[0048] Figure 2 It is a structural diagram of the sorting conveying roller;

[0049] Figure 3 for Figure 2 Enlarged view of part A;

[0050] Figure 4 This is a front view of the sorting conveyor roller;

[0051] Figure 5 It is a side view of the sorting conveyor roller;

[0052] Figure 6 for Figure 5 Enlarged view of part B;

[0053] Figure 7 It is a front view of the sorting device of the present invention;

[0054] Figure 8 for Figure 7 Rear view;

[0055] Figure 9 This is a flow chart of coal gangue separation according to the present invention.

[0056] In the figure: 1. Crusher; 2. Crusher bottom guide plate; 3. Manual control valve; 4. Sorting conveyor roller; 5. Paddle; 6. Baffle; 7. Partition; 8. Conveyor belt; 9. Motor; 10. Terahertz signal transmitter; 11. Terahertz signal receiver and processor; 12. Crank; 13. High-precision angle sensor; 14. Discharge end guide plate; 15. Information processing system; 16. Belt; 17. Drying device. DETAILED DESCRIPTION

[0057] like Figures 1 to 9 As shown, this embodiment provides a coal gangue sorting device based on horizontal particle size classification and terahertz linear frequency modulation, including a crusher 1, a sorting conveyor roller 4, a conveyor belt 8, a crusher bottom guide plate 2 and an information processing system 15; the information processing system 15 includes a microprocessor located below the conveyor belt, and the microprocessor is respectively connected to a terahertz signal transmitting device 10, a terahertz signal receiving and processing device 11, a pressure sensor, a motor 9, and a high-precision angle sensor 13;

[0058] A discharge port is provided at the bottom of the crusher 1, and an adjustable angle bottom guide plate 2 is provided at the discharge port of the crusher 1. The opening and closing angle of the bottom guide plate 2 is controlled by the information processing system 15;

[0059] Two sets of sorting rollers 4 are located beneath the crusher 1. These rollers are parallel and tilted at an angle of 15° to 45° to the ground. They rotate continuously, controlled by a motor 9. Automatically opening and closing paddles 5 are located on one side of the rollers. A conveyor belt 8 is located beneath the sorting rollers 4. A partition 7 is installed in the middle of the conveyor belt 8, dividing it into three sections, each separated by a partition 7.

[0060] Two rows of brackets are arranged parallel to each other above the conveyor belt 8. A terahertz signal transmitter 10 and a terahertz signal receiver and processor 11 are installed on top of the brackets. The terahertz signal receiver and processor 11 is installed behind the terahertz signal transmitter 10. The terahertz signal receiver and processor 11 includes a signal receiver, a filter, and a mixer. The terahertz signal receiver and processor 11 is connected to the filter, which is directly connected to the mixer. The terahertz signal receiver and processor 11 is at the same height as the terahertz signal transmitter 10.

[0061] The sorting and conveying rollers 4 consist of an upper roller set and a lower roller set arranged in parallel. The gaps between the rollers in the upper roller set are smaller, while those in the lower roller set are larger. The gaps between each roller set can be adjusted to the desired particle size by rotating a motor 9 mounted on a bracket. Baffles are installed at the bottom ends of each roller set. A pressure sensor is installed within the sorting and conveying rollers and is connected to a microprocessor. This pressure sensor monitors the flow rate of the coal gangue and converts it into an electrical signal, which is transmitted to the microprocessor. The microprocessor analyzes the signal according to a preset program. When the pressure sensor signal exceeds a set high threshold, indicating a high coal gangue flow rate, the microprocessor activates an adjustment device to reduce the opening and closing angle of the crusher's bottom guide plate 2, allowing the coal gangue to fall dispersedly onto the roller set. When the signal falls below a set low threshold, indicating a low coal gangue flow rate, the microprocessor increases the opening and closing angle of the crusher's bottom guide plate 2, ensuring smooth coal gangue descent.

[0062] The automatic opening and closing mechanism of the paddle 5 is associated with the pressure sensor in the roller group. When the pressure in the roller reaches the preset upper limit due to coal gangue blockage, the pressure sensor sends a signal to the microprocessor, which controls the paddle to make the paddle 5 in the corresponding position pop out to clear the blockage. After the material is cleared, the pressure drops to the lower limit, and the pressure sensor feeds back a signal to the microprocessor, which controls the paddle to return to its position to ensure stable operation of the roller group.

[0063] At the tail end of conveyor belt 8, three sets of discharge end guide plates 14 of varying sizes are installed. These are controlled by an information processing system 15 to separate gangue and coal of varying particle sizes. A terahertz signal transmitter 10 transmits a terahertz signal, which is then reflected by the gangue. A terahertz signal receiver and processor 11 receives the reflected signal, filters it to remove noise and interference, and a mixer mixes the received terahertz signal with the local oscillator signal according to a specific formula to generate a difference frequency signal, which is then transmitted to the information processing system. The communication interface of information processing system 15 receives this difference frequency signal and transmits it to a microprocessor, which analyzes the signal based on a preset algorithm in a storage unit to identify coal and gangue.

[0064] When the microprocessor detects that the gangue has reached the discharge end guide plate 14, it rapidly controls the crank 12 to tilt the plate 14. During this process, a high-precision angle sensor 13 closely tracks the plate's tilting progress and feeds real-time angle data back to the microprocessor. Based on this feedback, the microprocessor precisely adjusts the extension and extension range and angle of the crank 12, ensuring that the plate 14 reaches the preset tilt angle with exceptional precision.

[0065] As a further optimization solution of the present invention, a drying device 17 is installed on the bracket close to the sorting and conveying roller 4.

[0066] As a further optimization solution of the present invention: a manual control valve 3 is provided on the side of the crusher 1, and the opening and closing of the guide plate 2 at the bottom of the crusher is manually adjusted when the crusher is shut down for maintenance.

[0067] As a further optimization scheme of the present invention: a main roller is provided in the middle portion below the upper and lower roller groups, and the main roller is connected to a motor 9, which drives the main roller to rotate. The main roller is connected to the intermediate rollers of the upper and lower roller groups and can rotate relative to each other. Adjacent rollers are connected by a belt 16. Driven by the motor 9, the intermediate rollers of the upper and lower roller groups rotate, thereby driving the remaining rollers to rotate. Specifically, the motor 9 drives the main roller to rotate. The main roller is connected to the intermediate rollers of the upper and lower roller groups respectively by belts 16. The upper and lower intermediate rollers are powered by the main roller, driving the intermediate rollers to rotate (relying on the friction between the rollers and the belt 16 to cause the belt 16 to circulate). The remaining adjacent rollers are connected by a belt 16. Driven by the intermediate rollers and the belt 16, the friction between the rollers and the belt 16 causes the belt 16 to circulate. The passive rollers passively rotate by friction with the belt 16, without the need for independent power.

[0068] As a further optimization scheme of the present invention: the frequency range of the linear frequency modulation signals emitted by the three terahertz linear frequency modulation signal transmitters 10 only includes the minimum and maximum frequencies required by coal gangue of different particle sizes; among them, the frequency corresponding to the small particle size is 3-5THz, the frequency corresponding to the medium particle size is 1-3THz, and the frequency corresponding to the large particle size is 0.5-1THz.

[0069] As a further optimization of the present invention, the three filters used for terahertz signal processing are placed within a shielding box in the device design. Made of materials with excellent electromagnetic shielding properties, this shielding box effectively blocks the effects of external electromagnetic interference signals on the filters, ensuring that the filters maintain stable and efficient operation during terahertz signal processing. This, in turn, safeguards the signal processing accuracy and reliability of the entire coal gangue sorting device, enabling smooth coal gangue identification and sorting operations based on terahertz linear frequency modulation technology.

[0070] As a further solution of the present invention, determining the position and category of the current target using data obtained from the terahertz linear frequency modulation signal specifically includes:

[0071] First, the signal transmitter transmits a linear frequency modulated terahertz signal. The transmitted signal is:

[0072]

[0073] Where S T Indicates the transmission signal, A T is the amplitude of the transmitted signal, f0 is the starting frequency, K is the frequency modulation slope, t is the time, and the imaginary unit j is the sine or cosine signal.

[0074] After being reflected by the coal gangue to be measured, the transmitted signal is mixed with the echo signal to obtain the difference frequency signal. The difference frequency signal formula is:

[0075]

[0076] Where A is the signal amplitude; f0 is the starting frequency; K is the frequency modulation slope (which is the ratio of the signal bandwidth B to the period T); is the delay between the transmitted signal and the echo signal, R is the distance to the object to be measured, C = 3 × 10 8 m / s is the speed of electromagnetic waves in a vacuum.

[0077] In the actual calculation process, due to The term is very small and can be ignored. Substitute it into Kτ and the frequency of the difference frequency signal is The difference frequency is determined by fast Fourier transform, and the peak value f of the obtained amplitude-frequency curve is IFmax Corresponds to the position of the target.

[0078] The relationship between distance resolution and bandwidth in air is:

[0079] Where B represents the signal bandwidth.

[0080] In a medium with a dielectric constant of ε, the formula for the propagation speed of electromagnetic waves in the medium is Where v is the propagation speed of electromagnetic waves in the medium. Since the distance resolution is related to the propagation speed of electromagnetic waves, the distance resolution becomes

[0081] When m coal gangue mixtures pass through the test area, there will be m reflected echoes, and the corresponding amplitude-frequency curve will also have m peaks f IFmax, in order to obtain information at different depths of coal gangue and achieve the resolution of multiple interfaces. The distance between any two peaks is the electrical thickness of the layer of medium: i = 1, 2, ..., m; when m coal-gangue mixtures pass through the area to be measured, there will be m reflected echoes, and correspondingly, the amplitude-frequency curve will also have m peaks; each peak formed by the reflected echo on the amplitude-frequency curve has its corresponding number, and i (1~m) represents these numbers, that is, the number of the coal-gangue mixture; then, the information processing system can analyze and process different peaks separately to obtain information at different depths of the coal-gangue, and C represents the propagation speed of electromagnetic waves in a vacuum.

[0082] The relationship between gangue thickness, electrical thickness and dielectric constant is as follows:

[0083] Assume that the frequency of the transmitted linear frequency modulation signal is f(t)=f0+Kt;

[0084] Where f0 is the starting frequency, K is the frequency modulation slope, and t is the time.

[0085] When the signal penetrates the coal gangue, the received signal will produce a time delay, that is, the delay τ between the above signal and the echo signal. According to the formula The thickness of coal gangue can be calculated.

[0086] In summary, the dielectric constant of the coal gangue to be measured is calculated based on the thickness and electrical thickness of the coal gangue. Coal and gangue can be identified based on the difference in dielectric constants.

[0087] As a further aspect of the present invention, the three sets of end-of-discharge guide plates 14 are mounted on a fixed frame at the end of the conveyor belt 8, and the fixed frame has the same width as the conveyor belt 8. The three sets of end-of-discharge guide plates 14 are spatially positioned slightly lower than the horizontal plane of the conveyor belt 8. The fixed frame and end-of-discharge guide plates 14 are connected by a crank 12. The crank 12 is located at the bottom of the end-of-discharge guide plates 14 and is connected to a high-precision angle sensor 13, which is mounted on the fixed frame and connected to a microprocessor. The three sets of end-of-discharge guide plates 14 are controlled in level and tilt by an information processing system 15. When material slides onto the end-of-discharge guide plates 14, the information processing system 15 issues a command to the crank 12, causing the end-of-discharge guide plates 14 to tilt downward by 30° to 60°, allowing the waste rock to fall into the waste rock transfer assembly and be transported to the goaf, while the coal continues to be transported along the conveyor belt to subsequent processing areas.

[0088] The present invention provides a method for sorting coal gangue using the above-mentioned coal gangue sorting device based on horizontal particle size classification and terahertz linear frequency modulation, comprising the following steps:

[0089] (1) After the material enters the crusher 1 and is crushed, it falls onto the roller group through the guide plate 2 at the bottom of the crusher and then slides downward under the action of gravity. Small-sized materials fall onto the conveyor belt 8 below through the gaps between the upper roller group, medium-sized materials fall onto the conveyor belt 8 below through the gaps between the lower roller group, and large-sized materials slide directly onto the conveyor belt 8. That is, materials of different particle sizes fall onto the conveyor belt 8 separated by the partition 7.

[0090] (2) The coal gangue mixture divided into three particle sizes is transmitted through a terahertz linear frequency modulation signal by a transmitting device, and then a receiving device receives the terahertz linear frequency modulation signal reflected by the coal gangue, and removes noise through a connected filter, and then transmits it to a mixer connected to the filter, and the mixer mixes the received terahertz signal with a local oscillator signal, and finally transmits it to the information processing system 15 for processing;

[0091] (3) When the gangue slides to the guide plate 14 at the end of the discharge, the information processing system 15 will issue a command to control the guide plate 14 at the end of the discharge to tilt downward by 30° to 60°. When the information processing system 15 detects that the gangue has arrived at the guide plate 14 at the end of the discharge, it will immediately send a precise control command to the crank 12. Driven by the command, the crank 12 moves quickly, pushing the guide plate 14 at the end of the discharge to start tilting. During this process, the high-precision angle sensor 13 closely tracks the tilting process of the guide plate 14 at the end of the discharge and feeds back the real-time angle data to the information processing system 15. The information processing system 15 then accurately controls the extension and contraction range and angle of the crank 12 based on a large amount of feedback data, ensuring that the guide plate 14 at the end of the sorting discharge can reach the preset tilt angle with extremely high precision.

[0092] In actual coal mining scenarios, the device of the present invention can be flexibly adjusted according to specific production needs. For example, if the gangue content of the mined coal seam fluctuates significantly, the sensitivity of the angle adjustment of the guide plate 2 at the bottom of the crusher can be appropriately increased to ensure that the distribution area of ​​the coal gangue flow is promptly expanded as the gangue content increases, facilitating subsequent accurate sorting.

[0093] For the use of the sorting and conveying rollers 4, the initial roller spacing between the upper and lower roller groups can be set in advance based on the characteristics of the coal gangue particle size distribution. For example, in the early stages of coal mining, when there is a large amount of small-sized coal gangue, the roller spacing of the upper roller group can be initially set to a small value, while the roller spacing of the lower roller group can be set to a moderate value. As mining progresses, if the proportion of large-sized coal gangue increases, the roller spacing can be adjusted in a timely manner to adapt to the new particle size distribution.

[0094] The frequency range of the terahertz signal transmitter 10 can also be optimized based on the actual characteristics of the coal gangue. If the dielectric constant of a certain type of coal gangue is found to be significantly different from that of conventional coal gangue, affecting the recognition accuracy, the frequency range of the transmitted signal can be fine-tuned to improve the recognition accuracy of that type of coal gangue.

[0095] The control logic of the discharge end guide plate 14 can also be further refined. For example, when the gangue content is high, the response speed of the discharge end guide plate 14 can be accelerated to prevent gangue from accumulating there and affecting sorting efficiency. At the same time, the tilt angle of the discharge end guide plate 14 can be dynamically adjusted according to the coal flow rate and gangue distribution to ensure that the gangue falls accurately into the transfer assembly and the coal is transported smoothly.

[0096] Through the above-described specific implementation, the present invention can effectively achieve precise separation of coal gangue under various coal mining conditions, improving coal quality and resource utilization while reducing gangue processing costs and environmental impact. Furthermore, the various components of the device can be flexibly adjusted according to actual needs, demonstrating its high practicality and adaptability.

Claims

1. A coal gangue separation device based on horizontal particle size classification and terahertz linear frequency modulation, characterized by: It includes a crusher, a sorting conveyor roller, a conveyor belt, a guide plate and an information processing system; the information processing system includes a microprocessor located under the conveyor belt, and the microprocessor is respectively connected to a terahertz signal transmitter, a terahertz signal receiving and processing device, a pressure sensor, a motor, and a high-precision angle sensor; A discharge port is provided at the bottom of the crusher, and an adjustable angle guide plate is provided at the discharge port of the crusher. The opening and closing angle of the guide plate is controlled by the information processing system; Two sets of sorting and conveying rollers are installed below the crusher. These rollers are parallel and tilted at an angle of 15° to 45° to the ground. They rotate continuously under the control of a motor. Automatically opening and closing paddles are installed on one side of the rollers. A conveyor belt is installed below the sorting and conveying rollers. A partition is installed in the middle of the conveyor belt, dividing it into three sections, each separated by a partition. A pressure sensor is installed inside the sorting and conveying rollers. This pressure sensor is connected to a microprocessor and is responsible for monitoring the flow of coal gangue and converting it into an electrical signal for transmission to the microprocessor. Two rows of brackets are arranged in parallel above the conveyor belt. Three sets of terahertz signal transmitting devices and three sets of terahertz signal receiving and processing devices are installed on the top of the brackets. A terahertz signal receiving and processing device is installed behind the terahertz signal transmitting device. The terahertz signal receiving and processing device includes a signal receiver, a filter, and a mixer. The terahertz signal receiving and processing device is connected to the filter, and the filter is directly connected to the mixer. The terahertz signal receiving and processing device is at the same height as the terahertz signal transmitting device. Three groups of discharge end guide plates of different sizes are provided at the tail end of the conveyor belt. The discharge end guide plates are controlled by an information processing system to sort out gangue and coal of different particle sizes.

2. The coal gangue separation device based on horizontal particle size classification and terahertz linear frequency modulation according to claim 1, characterized in that: The sorting and conveying rollers are composed of an upper roller group and a lower roller group arranged in parallel. The gaps between the rollers in the upper roller group are smaller, while the gaps between the rollers in the lower roller group are larger. The gaps between the rollers in each group can be changed according to the required particle size by rotating the motor installed on the bracket. The automatic opening and closing of the paddles is associated with the pressure sensor in the roller group. When the coal gangue is blocked and the pressure in the roller reaches a preset upper limit, the pressure sensor sends a signal to the microprocessor, which controls the paddles to make the paddles in the corresponding position pop out to clear the blockage. After the material is cleared, the pressure drops to the lower limit, and the pressure sensor feeds back a signal to the microprocessor, which controls the paddles to return to their positions to ensure stable operation of the roller group.

3. The coal gangue separation device based on horizontal particle size classification and terahertz linear frequency modulation according to claim 2, characterized in that: A main roller is provided in the middle portion below the upper roller group and the lower roller group. The main roller is connected to a motor and is driven to rotate by the motor. The main roller is connected to the middle rollers of the upper roller group and the lower roller group and can rotate relative to each other. The adjacent rollers are connected by a belt. Driven by the motor, the middle rollers of the upper roller group and the lower roller group rotate, thereby driving the remaining rollers to rotate.

4. The coal gangue separation device based on horizontal particle size classification and terahertz linear frequency modulation according to claim 1, characterized in that: After the terahertz signal transmitting device transmits the terahertz signal, it is reflected by the coal gangue. The terahertz signal receiving and processing device receives the reflected signal, and the filter removes the noise and interference. The mixer mixes the received terahertz signal with the local oscillator signal according to a specific formula to obtain a difference frequency signal and transmit it to the information processing system; the communication interface of the information processing system receives this difference frequency signal and transmits it to the microprocessor. The microprocessor analyzes the signal according to the preset algorithm in the storage unit and identifies coal and gangue.

5. The coal gangue separation device based on horizontal particle size classification and terahertz linear frequency modulation according to claim 4, characterized in that: Three terahertz linear frequency modulation signal transmitters are set up corresponding to three conveyor belts respectively. The frequency range of the emitted linear frequency modulation signals only includes the minimum and maximum frequencies required for coal gangue of different particle sizes; among them, the frequency corresponding to small particle size is 3-5THz, the frequency corresponding to medium particle size is 1-3THz, and the frequency corresponding to large particle size is 0.5-1THz.

6. The coal gangue separation device based on horizontal particle size classification and terahertz linear frequency modulation according to claim 4, characterized in that: The data obtained from the terahertz linear frequency modulation signal is used to determine the location and type of the current target, including: First, a linear frequency modulated terahertz signal is transmitted through the signal transmitter; the transmitted signal is: Where S T Indicates the transmission signal, A T is the amplitude of the transmitted signal, f0 is the starting frequency, K is the frequency modulation slope, t is the time, and the imaginary unit j is the sine or cosine signal; After being reflected by the coal gangue to be measured, the transmitted signal is mixed with the echo signal to obtain the difference frequency signal. The difference frequency signal formula is: Where A is the signal amplitude; f0 is the starting frequency; K is the frequency modulation slope; is the delay between the transmitted signal and the echo signal, R is the distance to the object to be measured, C = 3 × 10 8 m / s is the propagation speed of electromagnetic waves in vacuum; In the actual calculation process, due to The term is very small and can be ignored; Substitute it into Kτ and the frequency of the difference frequency signal is The difference frequency is determined by fast Fourier transform, and the peak value f of the obtained amplitude-frequency curve is IFmax corresponds to the location of the target; The relationship between distance resolution and bandwidth in air is: Where B represents the signal bandwidth; In a medium with a dielectric constant of ε, the formula for the propagation speed of electromagnetic waves in the medium is Where v is the propagation speed of electromagnetic waves in the medium; since the distance resolution is related to the propagation speed of electromagnetic waves, the distance resolution becomes When m coal gangue mixtures pass through the test area, there will be m reflected echoes, and the corresponding amplitude-frequency curve will also have m peaks f IFmax , in order to obtain information at different depths of coal gangue and realize the resolution of multiple interfaces in the distance direction; the distance between any two peaks is the electrical thickness of the layer of medium: C = 3 × 10 8 m / s is the propagation speed of electromagnetic waves in a vacuum; i = 1, 2, ..., m; when m coal-gangue mixtures pass through the test area, there will be m reflected echoes, and correspondingly, m peaks will appear in the amplitude-frequency curve; each peak formed by the reflected echo on the amplitude-frequency curve has a corresponding number, and i is the number of the coal-gangue mixture; the information processing system can then analyze and process the different peaks separately to obtain information at different depths of the coal-gangue; The relationship between gangue thickness, electrical thickness and dielectric constant is as follows: Assume that the frequency of the transmitted linear frequency modulation signal is f(t)=f0+Kt; Where f0 is the starting frequency, K is the frequency modulation slope, and t is the time; When the signal penetrates the coal gangue, the received signal will produce a time delay, that is, the delay τ between the above signal and the echo signal. According to the formula The thickness of coal gangue can be calculated; In summary, the dielectric constant value of the coal gangue to be measured is calculated according to the thickness and electrical thickness of the coal gangue; and coal and gangue are identified according to the difference in dielectric constants.

7. The coal gangue separation device based on horizontal particle size classification and terahertz linear frequency modulation according to claim 1, characterized in that: The three groups of guide plates at the end of the discharge are installed on a fixed frame at the tail end of the conveyor belt, and the width of the fixed frame is the same as the width of the conveyor belt; the three groups of guide plates at the end of the discharge are slightly lower than the horizontal plane of the conveyor belt in spatial position; the fixed frame and the guide plates at the end of the discharge are connected by a crank, and a crank is provided at the bottom of the guide plates at the end of the discharge, and the crank is connected to a high-precision angle sensor, which is arranged on the fixed frame and connected to a microprocessor.

8. The coal gangue separation device based on horizontal particle size classification and terahertz linear frequency modulation according to claim 7, characterized in that: The three groups of guide plates at the end of the discharge are controlled in terms of level and inclination by the information processing system. When the microprocessor detects that the gangue has arrived at the guide plates at the end of the discharge, the crank is controlled to move quickly to push the guide plates at the end of the discharge to start tilting. The high-precision angle sensor closely tracks the tilting process of the guide plates at the end of the discharge and feeds back the real-time angle data to the microprocessor. The microprocessor accurately adjusts the extension and extension amplitude and angle of the crank based on the received feedback data to ensure that the guide plates at the end of the sorting discharge can reach the preset tilt angle with extremely high precision.

9. The coal gangue separation device based on horizontal particle size classification and terahertz linear frequency modulation according to claim 1, characterized in that: A drying device is installed on a bracket close to the sorting and conveying roller.

10. A method for separating coal gangue using the coal gangue separation device based on horizontal particle size separation and terahertz linear frequency modulation according to any one of claims 1 to 9, characterized in that The following steps are involved: (1) After the material enters the crusher and is crushed, it falls onto the roller group through the guide plate at the bottom of the crusher and then slides downward under the action of gravity. Small-sized materials fall onto the conveyor belt below through the gap between the upper roller group, medium-sized materials fall onto the conveyor belt below through the gap between the lower roller group, and large-sized materials slide directly onto the conveyor belt; that is, materials of different particle sizes fall onto conveyor belts separated by partitions. (2) The coal gangue mixture divided into three particle sizes is transmitted through a terahertz linear frequency modulation signal by a transmitting device, and then the terahertz linear frequency modulation signal reflected by the coal gangue is received by a receiving device, and is de-noised by a connected filter, and then transmitted to a mixer connected to the filter, and the mixer mixes the received terahertz signal with a local oscillator signal, and finally transmitted to an information processing system for processing; (3) When the gangue slides to the guide plate at the end of the discharge, the information processing system will issue an instruction to control the guide plate at the end of the discharge to tilt downward by 30° to 60°. When the information processing system detects that the gangue has arrived at the guide plate at the end of the discharge, it will immediately send a precise control instruction to the crank; driven by the instruction, the crank moves quickly, pushing the guide plate at the end of the discharge to start tilting. During this process, the high-precision angle sensor closely tracks the tilting process of the guide plate at the end of the discharge and feeds back the real-time angle data to the information processing system.

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