Intelligent coal caving method for fully-mechanized caving mining of extra-thick coal seam

Abstract

The invention discloses an intelligent coal caving method for fully-mechanized caving mining of an extra-thick coal seam, which comprises the following steps of: after confirming working parameters of a detector for fully-mechanized caving mining of the extra-thick coal seam, combining a detection result of the detector with a caving flow mixing rule of coal, gangue and immediate roof of the extra-thick coal seam with a complex structure; the method comprises the following steps: analyzing a radiation change rule of a coal, gangue and rock caving heterogeneous medium mixed state flow, combining the radiation change rule with field radiation value change data to obtain a window closing parameter, and finally confirming that an immediate roof is caved when coal caving is performed on a working face and an average value of detection results of the radiation value for continuous 5 seconds exceeds 160 cps, so that the immediate roof is caved. At the moment, the worker can directly close the window and end the coal caving procedure after checking the safety of the environment, and in the process, the traditional technology and the intelligent technology are effectively shared and fused, so that during fully mechanized caving mining of the extra-thick coal seam, all coal can be caved, mining is efficient and thorough, intelligent coal caving of top coal caving of the extra-thick coal seam is achieved, and the resource utilization rate is increased.

Description

Technical Field

[0001] The present invention specifically relates to an intelligent coal caving method for fully mechanized caving mining of extra-thick coal seams. Background Art

[0002] With the continuous growth of society's demand for energy, coal, as my country's main energy source, has a stable supply that is vital to the country's economic development. In today's environment, intelligent technology has become the key to promoting the upgrading of the coal industry chain. Among them, coal and rock identification technology, as the basis for realizing the intelligent construction of coal mines, plays a decisive role in improving the accuracy and efficiency of coal seam detection, intelligent mining, and rapid sorting. At present, with the application of advanced technologies such as big data, artificial intelligence, and the Internet of Things, the production model and management method of the coal industry are undergoing unprecedented changes. Intelligent mining can not only greatly improve the safety and efficiency of operations, but also realize the efficient and low-loss utilization of coal resources, reduce environmental pollution, and promote the transformation of the coal industry towards sustainable development.

[0003] However, when fully-mechanized mining is carried out in extra-thick coal seams, it is still difficult for traditional technologies to share and integrate data with intelligent technologies, technical standards cannot be unified, and incomplete mining often occurs, resulting in the inability to rationally mine and utilize coal resources and low resource utilization, which urgently needs to be improved.

[0004] Therefore, it is necessary to invent an intelligent coal caving method for fully-mechanized caving mining of extra-thick coal seams to solve the above problems. Summary of the invention

[0005] The purpose of the present invention is to provide an intelligent coal caving method for fully mechanized top coal caving in extra-thick coal seams. After confirming the working parameters of the detector used for fully mechanized top coal caving in extra-thick coal seams, the detection results of the detector are combined with the mixing law of the caving flow of coal, gangue and direct roof in complex structure extra-thick coal seams, and the radiation change law of the heterogeneous mixed state flow of coal, gangue and rock caving is analyzed. The radiation change law is then combined with the field radiation value change data to obtain the window closing parameter, and finally it is confirmed that when coal is caving at the working face, when the average value of the radiation value detection result exceeds 160cps for 5 consecutive seconds, it means that the direct roof has been caving, so that during the fully mechanized top coal caving in extra-thick coal seams, all the coal can be caving, and the mining is efficient and thorough, realizing the intelligent coal caving of top coal in extra-thick coal seams, improving resource utilization, so as to solve the above-mentioned deficiencies in the technology.

[0006] In order to achieve the above object, the present invention provides the following technical solution: an intelligent coal caving method for fully mechanized caving mining of extra-thick coal seams, comprising the following steps:

[0007] Step 1: Calculate the mixing law of coal, gangue and direct roof in the complex structure and extra thick coal seam;

[0008] Step 2, determining the working parameters of the detector used in fully mechanized caving mining of complex structure and extra thick coal seams;

[0009] Step 3, according to the mixing law of falling flow and the detection results of the detector, the radiation change law of the falling heterogeneous medium mixed state flow of coal, gangue and direct roof of the complex structure and extra-thick coal seam is obtained;

[0010] Step 4: According to the radiation change law of the heterogeneous mixed state flow, the window closing production number is obtained to realize intelligent coal placement.

[0011] In the aforementioned intelligent coal caving method for fully mechanized caving mining of extra-thick coal seams, in step 1, the caving flow mixing law includes the influence of the thickness of interlayer gangue on the caving flow sequence of coal, gangue and direct roof;

[0012] The influence of the spacing between interlayers of gangue on the timing of the fall and flow of coal, gangue and direct roof;

[0013] And the changing law of mixed waste rate.

[0014] The aforementioned intelligent coal caving method for fully mechanized caving mining in extra-thick coal seams, wherein the influence law of the caving flow sequence of coal, gangue and direct roof is calculated, has the following specific steps:

[0015] 1.1. Assign different parameters to coal, gangue and direct roof;

[0016] 1.2. According to the given parameters, simulate the influence of the thickness of interlayer gangue on the fall flow sequence of coal, gangue and direct roof, specifically:

[0017] Specifically: under the condition of a single layer of interlayer gangue and a fixed spatial position of the interlayer gangue, the thickness of the interlayer gangue was changed and simulated six times to obtain the running time for the first appearance of gangue and the first appearance of the top, and the influence of the thickness of the interlayer gangue on the falling flow sequence of coal, gangue and direct roof was analyzed.

[0018] The aforementioned intelligent coal caving method for fully mechanized caving mining in extra-thick coal seams calculates the influence of the spacing between interlayers on the caving flow sequence of coal, gangue and direct roof, as follows:

[0019] 1.3. According to the given parameters, simulate the influence of the spacing between interlayers on the timing of the fall flow of coal, gangue and direct roof, specifically:

[0020] Under the condition of multiple layers of interlayered gangue with fixed thickness, the spatial layer of interlayered gangue is changed, and the interlayered gangue layers are marked from bottom to top. The spacing between interlayered gangue layers is simulated and analyzed, and the influence of the spacing between interlayered gangue layers on the falling flow sequence of coal, gangue and direct roof is obtained.

[0021] The above-mentioned intelligent coal caving method for fully mechanized caving mining of extra-thick coal seams, wherein the changing law of mixed gangue ratio is calculated, has the following specific steps:

[0022] 1.4. In PFC3D, the mass and changes of all particles in a certain area are recorded in real time, and the changing law of the ratio of the mass of gangue contained in the coal at the coal discharge port to the total mass during the coal discharge process, that is, the changing law of the mixed gangue rate, is obtained, including the following steps:

[0023] 1.4.1. Assuming that there are m coal particles, n gangue particles, and a direct top particles in the designated coal discharge port area at a certain time, the calculation formula for the mixed gangue rate P is as follows:

[0024] M 煤 =mρ 煤 / 4πR 煤 3

[0025] M 矸 =nρ 煤 / 4πR 矸 3

[0026] M 直 =aρ 煤 / 4πR 直 3

[0027] P=(M 矸 +M 直 ) / (M 煤 +M 矸 +M 直 )

[0028] Where M is the number density of coal particles per unit volume;

[0029] 1.4.2. Under the condition of single interlayer of gangue and fixed interlayer space, the change of mixed gangue ratio was simulated six times, specifically:

[0030] Under the condition of single interlayer and fixed interlayer space, the thickness of interlayer was changed and simulated six times, and the initial mixed gangue rate-operation step change curve was obtained, and the change law of mixed gangue rate was analyzed.

[0031] 1.4.3. Under the condition of multi-layer intercalated gangue, the changes of mixed gangue ratio were simulated seven times, specifically:

[0032] Under the condition of multiple layers of interlayers with fixed thickness, the spatial layer of interlayers was changed for seven simulations, and the initial mixed gangue rate-operating step number change curve was obtained, and the changing law of mixed gangue rate was obtained by analysis.

[0033] In the aforementioned intelligent coal caving method for fully mechanized caving mining of extra-thick coal seams, in step 2, the working parameters of the detectors include the number of detectors arranged, the optimal output working voltage of the photomultiplier tube, and the size of the detectors;

[0034] Among them, the specific steps to determine the working parameters of the detector used in fully mechanized caving mining of complex structure and extra-thick coal seams are as follows:

[0035] 2.1. Calculate the number of detectors to be arranged, specifically:

[0036] Use a blackout cloth to cover the detector light source, connect the circuit, operate the power knob to adjust the voltage, record the multimeter reading at each voltage, and then connect the oscilloscope to measure the starting current and working current. Combined with the intrinsically safe power supply manual, confirm the number of detectors to be arranged;

[0037] 2.2. Determine the optimal output operating voltage of the photomultiplier tube, specifically:

[0038] Use a shading cloth to cover the photomultiplier tube, install a multimeter on the high-voltage module, measure the voltage of the photomultiplier tube, operate the voltage knob of the high-voltage module to adjust the working voltage of the photomultiplier tube, record 2 minutes of data every 10V, get 1200 data in each group, take the average value to make a line graph, and analyze to get the best output working voltage of the photomultiplier tube;

[0039] 2.3. Determine the size of the detector, which is measured on-site in the laboratory.

[0040] The aforementioned intelligent coal caving method for fully mechanized caving mining in extra-thick coal seams, in step 3, obtains the radiation change law of the caving heterogeneous mixed state flow of coal, gangue and direct roof in complex structure extra-thick coal seams according to the caving flow mixing law and the detection results of the detector. The specific steps are:

[0041] 3.1. Measure the background radiation of the coal opening environment of the fully mechanized caving working face and determine the threshold voltage of the detector, specifically:

[0042] After the detector is set up in the underground production working face, the threshold voltage is adjusted upward step by step from 0 to obtain the background radiation value change diagram under different threshold voltages;

[0043] 3.2. Install a detector to confirm the threshold voltage at the coal caving opening of the fully mechanized caving working face, and carry out normal coal caving work after all debugging is completed;

[0044] 3.3. Use Matlab to process the radiation value change data detected by the detector during the coal discharge process, sort out the radiation change diagram, and analyze the radiation change law of the discharged heterogeneous medium mixed state flow.

[0045] In the aforementioned intelligent coal caving method for fully mechanized caving of extra-thick coal seams, in step 4, the window closing production number is obtained according to the radiation change law of the heterogeneous medium mixed state flow, and intelligent coal caving is realized. The specific steps are as follows:

[0046] 4.1. Select the most representative radiation value change graph again, as shown in the attached Fig.14 As shown;

[0047] 4.2. Use Matlab to calculate the average radiation value every 5 seconds in the radiation change diagram, and make a fitting curve diagram of the radiation value and time scatter points. According to the radiation change law of the heterogeneous mixed state flow, the window closing production number is obtained to realize intelligent coal release.

[0048] Compared with the prior art, the present invention has the following beneficial effects:

[0049] The present invention simulates and analyzes the caving process of top coal in complex structure and extra-thick coal seams, obtains the caving flow mixing law of coal, gangue and direct roof in complex structure and extra-thick coal seams, selects photomultiplier tubes as the main detection devices, adjusts the working parameters of the overall detection system, and after a round of coal caving, analyzes the radiation change law of the heterogeneous mixed state flow of coal, gangue and rock in combination with the caving flow mixing law and the detection result of the detector, and combines the radiation change law with the field radiation value change data to obtain the window closing parameter, and finally confirms that when coal is caving at the working face, when the average value of the radiation value detection result exceeds 160cps for 5 consecutive seconds, it means that the direct roof has been caving. At this time, the workers can directly close the window after checking the safety of the environment to end the coal caving process. In this process, traditional technology and intelligent technology are effectively shared and integrated, so that when fully-mechanized caving of extra-thick coal seams is carried out, all coal can be caved, and the mining is efficient and thorough, thereby realizing intelligent caving of top coal in extra-thick coal seams and improving resource utilization. BRIEF DESCRIPTION OF THE DRAWINGS

[0050] In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the drawings required for use in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments recorded in the present invention. For ordinary technicians in this field, other drawings can also be obtained based on these drawings.

[0051] Figure 1 is a flow chart of the present invention;

[0052] Figure 2 It is a simulation schematic diagram when the thickness of the gangue is 0.5m;

[0053] Figure 3 It is a line chart of simulation results under the condition of single-layer intercalated gangue;

[0054] Figure 4 This is a schematic diagram of the simulation of the influence of the spacing between interlayers of gangue;

[0055] Figure 5 It is a bar chart of simulation results of the influence of the spacing between interlayers of gangue;

[0056] Figure 6 It is a line chart of the simulation results of the mixed gangue rate change under single-layer intercalated gangue;

[0057] Figure 7 It is a line chart of simulation results of mixed gangue rate change under multi-layer intercalated gangue;

[0058] Figure 8 This is a schematic diagram of the current experiment interface;

[0059] Fig. 9 Circuit diagram when using intrinsically safe power supply;

[0060] Fig.10 It is the dark radiation variation curve;

[0061] Fig.11 It is the change diagram of background radiation value under different threshold voltages;

[0062] Fig.12 This is the radiation value change diagram during coal placement;

[0063] Fig.13 This is the radiation value variation diagram during the coal caving process selected again;

[0064] Fig.14 This is a graph showing the change in the average radiation value every 5 seconds. DETAILED DESCRIPTION

[0065] In order to enable those skilled in the art to better understand the technical solution of the present invention, the present invention will be further described in detail below with reference to the accompanying drawings.

[0066] The present invention provides Figure 1-14 The intelligent coal caving method for fully mechanized caving of extra-thick coal seams shown in the figure comprises the following steps:

[0067] Step 1: Calculate the mixing law of coal, gangue and direct roof in the complex structure and extra thick coal seam;

[0068] Among them, the mixing law of falling flow includes the influence of the thickness of interlayer gangue on the falling flow sequence of coal, gangue and direct roof;

[0069] The influence of the spacing between interlayers of gangue on the timing of the fall and flow of coal, gangue and direct roof;

[0070] And the changing law of mixed waste ratio;

[0071] PFC3D can also be used to simulate and analyze the caving process of top coal in complex and extra-thick coal seams, thereby calculating the caving flow mixing law;

[0072] Among them, the influence rules of the fall flow sequence of coal, gangue and direct roof are calculated, and the specific steps are as follows:

[0073] 1.1. Assign different parameters to coal, gangue and direct roof, see Table 1 for details;

[0074] Table 1

[0075]

[0076] 1.2. According to the given parameters, simulate the influence of the thickness of interlayer gangue on the timing of the fall and flow of coal, gangue and direct roof;

[0077] Specifically, under the condition of single-layer interlayer and fixed interlayer space, the thickness of interlayer was changed and simulated six times, and the operation time of first seeing the gangue and first seeing the top was obtained, and Table 2 was prepared and organized into the attached table. Figure 3 ;

[0078] Table 2

[0079]

[0080] From Table 2, Appendix Figure 3 It can be seen that under the condition of single interlayer and fixed interlayer position, the change of interlayer thickness has almost no effect on the time when the interlayer enters the coal discharge port;

[0081] Among them, the influence of the spacing between interlayers of gangue on the timing of the fall flow of coal, gangue and direct roof is calculated, as follows:

[0082] 1.3. According to the given parameters, simulate the influence of the spacing between interlayers on the timing of the fall flow of coal, gangue and direct roof;

[0083] Specifically, under the condition of multiple interlayers and fixed interlayer thickness, the interlayer space is changed, and the interlayer positions are marked from bottom to top to simulate and analyze the interlayer spacing;

[0084] Among them, as attached Figure 4 As shown in the figure, the interlayers are marked as ①, ②, ③, ④, ⑤, and ⑥ from bottom to top. In the simulation process, the interlayers at ③, ④, ②, ⑤, ①, and ⑥ are deleted in turn each time and filled with coal seams. The simulation results are made into Table 3 and organized into the attached table. Figure 5 ;

[0085] Table 3

[0086]

[0087]

[0088] Among them, in step 1.3, since the gangue and coal seam have different physical parameters, the change of the number of gangue particles in the simulation has a slight effect on the falling flow sequence, but in actual production, this difference can be ignored. Figure 5 It can be concluded that:

[0089] Under the condition of multiple layers of interlayers and fixed thickness of interlayers, the higher the interlayer is, the longer it takes for the interlayer to enter the coal discharge port. The time difference between interlayers at different levels entering the coal discharge port is only related to the interval between the layers.

[0090] Among them, the specific steps for calculating the changing law of mixed waste rate are as follows:

[0091] 1.4. In PFC3D, the mass and changes of all particles in a certain area are recorded in real time, and the changing law of the ratio of the mass of gangue contained in the coal at the coal discharge port to the total mass during the coal discharge process, that is, the changing law of the mixed gangue rate, is obtained, including the following steps:

[0092] 1.4.1. Assuming that there are m coal particles, n gangue particles, and a direct top particles in the designated coal discharge port area at a certain time, the calculation formula for the mixed gangue rate P is as follows:

[0093] M 煤 =mρ 煤 / 4πR 煤 3

[0094] M 矸 =nρ 煤 / 4πR 矸 3

[0095] M 直 =aρ 煤 / 4πR 直 3

[0096] P=(M 矸 +M 直 ) / (M 煤 +M 矸 +M 直 )

[0097] Where M is the number density of coal particles per unit volume, which is used to evaluate the density of coal particles in a specific space. The larger the value, the more coal particles there are in the same volume, and vice versa.

[0098] 1.4.2. Under the condition of single interlayer of gangue and fixed interlayer space, the change of mixed gangue ratio was simulated six times, specifically:

[0099] Under the condition of single interlayer and fixed interlayer space, the thickness of interlayer was changed and simulated six times to obtain the curve of initial mixed gangue rate-operation step number. The results are as follows: Figure 6 As shown;

[0100] By the attached Figure 6 It can be seen that under the condition of a single layer of interlayered gangue and a fixed interlayer space, the following two situations will occur:

[0101] When the thickness of the interlayer is less than 0.4m, the interlayer is released discontinuously due to its thinness, and even disconnected before entering the coal discharge port. During the coal discharge process, the mixed gangue rate starts to rise from 0 when the gangue is first seen, and then fluctuates within a certain range. During the coal discharge process, there will be an intermittent state of 0 mixed gangue rate; the mixed gangue rate increases significantly after the first peak, and fluctuates around 45% when it rises to around 45%.

[0102] When the thickness of the interlayer is greater than 0.4m, the interlayer is released continuously, and the mixed-gang ratio starts to rise from 0 when the gangue is first seen, and then fluctuates within a certain range. After the initial peak, the mixed-gang ratio increases significantly, and when it rises to around 45%, it fluctuates around 45%.

[0103] 1.4.3. Under the condition of multi-layer intercalated gangue, the changes of mixed gangue ratio were simulated seven times, specifically:

[0104] Under the condition of multiple layers of interlayers and fixed thickness of interlayers, the interlayer space was changed and simulated seven times to obtain the initial mixed gangue rate-operation step change curve. The results are as follows: Figure 7 As shown;

[0105] Among them, the curves from bottom to top are not deleted, deleted 3, 4, 2, 5, 1, 6 interlayers;

[0106] By the attached Figure 7 It can be seen that under the condition of multiple layers of interlayered gangue and fixed thickness of interlayered gangue, the mixing law of each layer of interlayered gangue is the same as that of a single layer of interlayered gangue, that is, the interlayered gangue layer is released in a continuous state, and the mixed gangue rate starts to rise from 0 when the gangue is first seen, then fluctuates within a certain range, and then slowly decreases until the interlayered gangue is completely released. When the gangue at a higher level enters the coal discharge port, the mixed gangue rate continues to rise from the upper layer, and the cycle continues like this; the mixed gangue rate increases significantly after the first peak, and fluctuates around 45% when it rises to around 45%.

[0107] In step 1, PFC3D is used to simulate and analyze the caving process of top coal in complex structure and extra-thick coal seams, and the caving flow mixing law of coal, gangue and direct top in complex structure and extra-thick coal seams is obtained. It can be seen that in the process of underground coal caving, coal, gangue and rock will be released in the order of spatial layers, and their mixing is regular, which indirectly verifies the feasibility of this application. The internal situation of the caving flow mixing of coal, gangue and direct top can be observed through the pfc numerical simulation software. The analysis of simulation results and internal phenomena can be used to infer the radiation change law of the caving heterogeneous mixed state flow of coal, gangue and direct top and the internal phenomena that occur such laws.

[0108] Step 2, determining the working parameters of the detector used in fully mechanized caving mining of complex structure and extra thick coal seams;

[0109] The working parameters of the detector include the number of detectors, the optimal output working voltage of the photomultiplier tube, and the size of the detector;

[0110] The specific steps for determining the working parameters of the detector used in fully mechanized caving mining of complex structure and extra-thick coal seams are as follows:

[0111] 2.1. Calculate the number of detectors to be arranged. Specifically, cover the detector light source with a blackout cloth, connect the circuit, operate the power knob to adjust the voltage, record the multimeter reading at each voltage, and then connect the oscilloscope to measure the starting current and working current. Combined with the intrinsically safe power supply manual, the specific results are as attached. Figure 8 As shown;

[0112] By the attached Figure 8 It can be seen that the starting current is about 150mA, and the working current of the whole equipment gradually decreases from 118.9ma to 83.9ma as the voltage increases;

[0113] At the same time, the parameters of the intrinsically safe power supply used underground are as follows in Table 4:

[0114] Table 4

[0115]

[0116] As shown in Table 4, the total current should not exceed 1.95A during startup, and the total current should be around 1000mA in the best working state of the power supply during normal operation.

[0117] In step 2.1, the normal working current of a device is about 100mA, and the starting current is about 150mA. From the working current, it can be obtained that the maximum number of detectors that an intrinsically safe power supply of this model can carry is 10. From the overcurrent protection, it can be obtained that the maximum number of detectors that an intrinsically safe power supply of this model can carry is 13. Finally, it is determined that the maximum number of detectors that an intrinsically safe power supply of this model can carry is 10.

[0118] Among them, intrinsically safe power supply parameters refer to a series of electrical parameter standards that must be followed when designing and using intrinsically safe electrical equipment, and the specific circuit is attached. Fig. 9 As shown:

[0119] In step 2.1, the detector includes a power supply, a circuit board and its components, a high-voltage module, and a photomultiplier tube. The measuring equipment is a multimeter and an oscilloscope. When measuring, the voltage is set to 10-14V, and the voltage is increased by 0.1V intervals. The data of the starting current, the working current, and the voltage of the high-voltage module are measured at different voltages.

[0120] 2.2. Determine the optimal output working voltage of the photomultiplier tube. Specifically, cover the photomultiplier tube with a shading cloth, install a multimeter on the high-voltage module, measure the voltage of the photomultiplier tube, operate the voltage knob of the high-voltage module to adjust the working voltage of the photomultiplier tube, record 2 minutes of data every 10V, and obtain 1200 data in each group. Take the average value to make a line graph, as shown in the attached figure. Fig.10 As shown;

[0121] The circuit diagram uses the circuit diagram in step 2.1, and the maximum voltage that the photomultiplier tube can withstand is 1250V according to the manual. Exceeding 1250V may damage the device. Preliminary measurements show that when the voltage is less than 1000V, the dark current output is almost 0, indicating that when the voltage is less than 1000V, the voltage is too small and the sensitivity of the photomultiplier tube is too low to detect any radiation. Therefore, the measurement range is determined to be 1000-1250V.

[0122] By the attached Fig.10 It can be seen that before 1120V, the dark radiation rises slowly with the increase of voltage, and the rising trend gradually increases. After 1120V, the rising slope of the curve is the largest and basically fixed. Therefore, in order to maximize the working voltage of the photomultiplier tube and minimize the influence of dark current, the working voltage of the photomultiplier tube should be determined to be 1120V.

[0123] Among them, when the photomultiplier tube is working, the device itself will generate radiation due to the influence of other factors such as current. At this time, the radiation value measured and output by the detector is called the dark radiation value. The working voltage of the photomultiplier tube is adjusted to adjust its sensitivity to radiation. Finally, a suitable value is selected to ensure its working state and reasonably filter the dark radiation.

[0124] In step 2.2, the photomultiplier tube is installed on a base controlled by a circuit board when working. The circuit board has the function of controlling the voltage provided by the high-voltage module to the photomultiplier tube and transmitting data.

[0125] 2.3. Determine the size of the detector;

[0126] In step 2.3, the minimum size of the detector is 25×20×5cm, which is measured in the laboratory.

[0127] When used underground, aluminum shielding is required to be installed in consideration of the influence of background radiation. To strengthen the shielding effect of the aluminum plate and increase the detection range of the detector, the size design principle is to design a larger detector as much as possible without affecting the coal placement. To protect the detector from being damaged by the falling coal gangue, the detector is installed on the bracket shielding beam. The swinging of the plug plate does not affect the detector. The detector is always under the protection of the shielding beam when coal is placed and the window is closed. During the coal placement process, the detection surface is facing the falling coal gangue.

[0128] After consulting the dimension drawing and instruction manual of the ZFY18000 / 28 / 53D hydraulic support shield beam used in the working face of Longwanggou Coal Mine, it was calculated that the maximum space that the support can accommodate is 45×35×10cm. During the actual installation, the convenience of on-site installation operation was considered, and flexible space was left for the support movement, and the detector size was determined to be 42.5×30×8cm.

[0129] In step 2, the photomultiplier tube is selected as the main detection device, and the working parameters of the overall detection system are adjusted. It is used as the final intelligent coal caving monitoring device to ensure that the detector can safely and reliably obtain the curve of radiation value changing with time during coal caving underground.

[0130] Step 3: According to the mixing law of falling flow and the detection results of the detector, the radiation change law of the falling heterogeneous medium mixed state flow of coal, gangue and direct roof of the complex structure and extra-thick coal seam is obtained. The specific steps are:

[0131] 3.1. Measure the background radiation of the coal opening environment of the fully mechanized caving working face and determine the threshold voltage of the detector, specifically:

[0132] After the detector is set up in the underground production working face, the threshold voltage is adjusted upward step by step from 0 to obtain the background radiation value change diagram under different threshold voltages;

[0133] In step 3.1, the detector will generate electronic filtering background radiation of different energies as the voltage changes. The specific results are shown in the attached Fig.11 As shown;

[0134] By the attached Fig.11 It can be seen that the curve is bounded by 0.3V. Before 0.3V, the background radiation value decreases rapidly with the increase of the threshold voltage. After 0.3V, the radiation value curve tends to be a straight line, and the background radiation does not change much with the increase of the threshold voltage. Combined with the economic principle, this application selects a threshold voltage value of 0.3V. It can be foreseen that during the coal discharge process, the detector radiation value should be around 130cps only when coal is discharged;

[0135] In step 3.1, the threshold voltage of the detector refers to the minimum voltage value at which the detector starts to work normally and can detect signals. It is very important to correctly set the working voltage of the detector to ensure that the detector can operate under optimal conditions and avoid damage to the device due to excessive voltage. When setting the working voltage, ensure that the voltage value is higher than the threshold voltage to ensure that the detector can effectively respond to the signal;

[0136] Background radiation refers to the natural radiation that always exists in the environment. It is composed of natural elements and radiation generated by human activities. The size and change of background radiation affect the change of radiation value during coal caving. Therefore, it is very necessary to measure and filter background radiation.

[0137] The relationship between the threshold voltage and background radiation is reflected in whether the detector can distinguish between the signal and the noise generated by the background radiation. Increasing the threshold voltage can reduce the false signal or interference caused by the background radiation. If the threshold voltage is set too low, the background radiation may cause the detector to generate a signal higher than the threshold, which will cause the detector to mistakenly record these background events as valid events. At the same time, if the threshold voltage is set too high, if the real event signal strength is close to the signal strength caused by the background radiation, then these real events may not be detected because they fail to reach the newly set high threshold.

[0138] 3.2. Install a detector to confirm the threshold voltage at the coal caving opening of the fully mechanized caving working face, and carry out normal coal caving work after all debugging is completed;

[0139] 3.3. Use Matlab to process the radiation value change data detected by the detector during the coal discharge process, sort out the radiation change diagram, and analyze the radiation change law of the mixed state flow of the dropping heterogeneous medium;

[0140] Since there are many radiation change diagrams and they are very similar, the most representative radiation change diagram is selected. The results are shown in the attached figure. Fig.12 As shown;

[0141] According to the mixing law of coal, gangue and rock falling flow obtained by numerical simulation in step 1, combined with the attached Fig.12 , the measured radiation value change data were analyzed, and it was found that there were three cases of radiation change in the mixed state flow of dropping heterogeneous media:

[0142] (1) The first layer of interlayered gangue enters the coal discharge port: This layer of interlayered gangue is relatively thin, and there will be a discontinuous state in the overall discharge process. Only a small amount of interlayered gangue is discharged during the 90-110s process, and the radiation level is the same as when only coal is discharged;

[0143] At this time, the change pattern of the radiation value of the attachment is as follows: the radiation value rises rapidly from 130cps to 150cps when the gangue is seen, and the radiation value is disconnected after a period of release, and immediately returns to the normal level. The overall radiation value fluctuates within the range of 130-150cps;

[0144] (2) The second layer of interlayered gangue enters the coal discharge port: this layer of interlayered gangue is thicker and is continuous during the entire discharge process;

[0145] The radiation value changes as follows: from the time the gangue is seen, the radiation value rises rapidly from 130cps to 150cps, and after reaching 150cps, it fluctuates around 150cps until it is completely released and then weakens to a normal level;

[0146] (3) Direct top entry into the coal discharge port: After the top enters the coal discharge port directly, the mixed gangue ratio rises rapidly to about 45%, so the change in radiation value is faster and larger than when mixed gangue is introduced;

[0147] The radiation value changes as follows: after the coal outlet reaches its peak for the first time, the radiation value rises linearly from 130cps to about 160cps, and then fluctuates within a certain range around 160cps.

[0148] In step 3, the detector with adjusted working parameters is installed in place underground, and the threshold voltage is set to filter the background radiation. At this point, all the preparatory work is completed. At this time, the detector is turned on to confirm that the radiation value change detection is normal and then the coal caving operation is carried out. After a round of coal caving is completed, all detector data are read to obtain a set of radiation value-time change curves during the coal caving process. The data is filtered and processed using MATLAB to obtain the fitted radiation value change curve that is easy to observe. The radiation value change curve is analyzed in combination with the mixing law of the caving flow in step 1 to obtain the radiation change law of the mixed state flow of coal, gangue and rock caving.

[0149] Step 4: According to the radiation change law of the heterogeneous medium mixed state flow, the window closing production number is obtained to realize intelligent coal placement. The specific steps are as follows:

[0150] 4.1. Select the most representative radiation value change graph again, as shown in the attached Fig.13 As shown;

[0151] 4.2. Use Matlab to calculate the average radiation value every 5 seconds in the radiation change diagram, and make a fitting curve diagram of the radiation value and time scatter points. According to the radiation change law of the heterogeneous mixed state flow, the window closing production number is obtained to realize intelligent coal discharge;

[0152] The fitting curve diagram is shown in the attached figure. Fig.14 As shown, the analysis of Fig.13 and 14 It can be seen that when the interlayer enters the coal discharge port, the radiation value does not exceed 160cps on average, while when the direct top enters the coal discharge port, the radiation value is above 160cps on average. Therefore, it can be set to close the window when the radiation value exceeds 160cps for 5 consecutive seconds.

[0153] In step 4, by combining the radiation change law obtained in step 3 with a set of on-site radiation value change data, it is analyzed that the average radiation value every 5 seconds when the interlayer is released and the direct top is released may be different. Matlab calculation is used to verify this idea, and finally it is set to close the window when the radiation value detection results exceed 160cps for 5 consecutive seconds. This value is verified after being brought into other data collected on-site, which further illustrates the effectiveness of this method. That is, when coal is released on the working face, first ensure that the detector obtains the radiation value change data normally, and then carry out the coal release operation. When the average value of the radiation value detection results exceeds 160cps for 5 consecutive seconds, the detector warns the worker that the direct top has been released. The worker closes the window after checking the safety of the environment, thereby realizing intelligent coal release.

[0154] In summary

[0155] The present invention simulates and analyzes the caving process of top coal in complex structure and extra-thick coal seam, obtains the caving flow mixing law of coal, gangue and direct top in complex structure and extra-thick coal seam, selects photomultiplier tube as the main detection device, adjusts the working parameters of the overall detection system, and after a round of coal caving, combines the caving flow mixing law and the detection result of the detector to analyze the radiation change law of the heterogeneous mixed state flow of coal, gangue and rock caving, combines the radiation change law with the field radiation value change data to obtain the window closing parameter, and finally confirms that when coal is caving at the working face, when the average value of the radiation value detection result exceeds 160cps for 5 consecutive seconds, It indicates that the direct top coal has been released. At this time, the workers can directly close the window after checking the environmental safety and end the coal releasing process. In this process, traditional technology and intelligent technology are effectively shared and integrated, so that when the extra-thick coal seam is fully mechanized and mined, all the coal can be released, and the mining is efficient and thorough. The intelligent top coal release of extra-thick coal seams is realized, and the resource utilization rate is high. At the same time, the technical standards of this method are unified, which reduces the difficulty of data sharing and integration between traditional technology and intelligent technology, realizes the rational mining and utilization of coal resources, accelerates the digital transformation of the coal industry, and continuously optimizes the strategies and paths of intelligent construction, which plays an important role in green and low-carbon development.

[0156] The above description is only by way of illustration of certain exemplary embodiments of the present invention. It is undoubted that those skilled in the art can modify the described embodiments in various ways without departing from the spirit and scope of the present invention. Therefore, the above drawings and descriptions are illustrative in nature and should not be construed as limiting the scope of protection of the claims of the present invention.

Claims

1. An intelligent coal caving method for fully mechanized caving mining of extra-thick coal seams, characterized by: The following steps are involved: Step 1: Calculate the mixing law of coal, gangue and direct roof in the complex structure and extra thick coal seam; Step 2, determining the working parameters of the detector used in fully mechanized caving mining of complex structure and extra thick coal seams; Step 3, according to the mixing law of falling flow and the detection results of the detector, the radiation change law of the falling heterogeneous medium mixed state flow of coal, gangue and direct roof of the complex structure and extra-thick coal seam is obtained; Step 4: According to the radiation change law of the heterogeneous mixed state flow, the window closing production number is obtained to realize intelligent coal placement.

2. The intelligent coal caving method for fully mechanized caving mining of extra-thick coal seams according to claim 1 is characterized by: In step 1, the mixing law of the falling flow includes the influence of the thickness of the interlayer gangue on the falling flow sequence of coal, gangue and direct roof; The influence of the spacing between interlayers of gangue on the timing of the fall and flow of coal, gangue and direct roof; And the changing law of mixed waste rate.

3. The intelligent coal caving method for fully mechanized caving mining of extra-thick coal seams according to claim 2 is characterized in that: Calculate the influence of the flow sequence of coal, gangue and direct roof. The specific steps are as follows: 1.

1. Assign different parameters to coal, gangue and direct roof; 1.

2. According to the given parameters, simulate the influence of the thickness of interlayer gangue on the fall flow sequence of coal, gangue and direct roof, specifically: Specifically: under the condition of a single layer of interlayer gangue and a fixed spatial position of the interlayer gangue, the thickness of the interlayer gangue was changed and simulated six times to obtain the running time for the first appearance of gangue and the first appearance of the top, and the influence of the thickness of the interlayer gangue on the falling flow sequence of coal, gangue and direct roof was analyzed.

4. The intelligent coal caving method for fully mechanized caving mining of extra-thick coal seams according to claim 2 is characterized in that: The influence of the spacing between interlayers of gangue on the timing of the fall flow of coal, gangue and direct roof is calculated, as follows: 1.

3. According to the given parameters, simulate the influence of the spacing between interlayers on the timing of the fall flow of coal, gangue and direct roof, specifically: Under the condition of multiple layers of interlayered gangue with fixed thickness, the spatial layer of interlayered gangue is changed, and the interlayered gangue layers are marked from bottom to top. The spacing between interlayered gangue layers is simulated and analyzed, and the influence of the spacing between interlayered gangue layers on the falling flow sequence of coal, gangue and direct roof is obtained.

5. The intelligent coal caving method for fully mechanized caving mining of extra-thick coal seams according to claim 2 is characterized in that: Calculate the changing law of mixed waste rate, the specific steps are as follows: 1.

4. In PFC3D, the mass and changes of all particles in a certain area are recorded in real time, and the changing law of the ratio of the mass of gangue contained in the coal at the coal discharge port to the total mass during the coal discharge process, that is, the changing law of the mixed gangue rate, is obtained, including the following steps: 1.4.

1. Assuming that there are m coal particles, n gangue particles, and a direct top particles in the designated coal discharge port area at a certain time, the calculation formula for the mixed gangue rate P is as follows: M 煤 =mρ 煤 / 4πR 煤 3 M 矸 =nρ 煤 / 4πR 矸 3 M 直 =aρ 煤 / 4πR 直 3 P=(M 矸 +M 直 ) / (M 煤 +M 矸 +M 直 ) Where M is the number density of coal particles per unit volume; 1.4.

2. Under the condition of single interlayer of gangue and fixed interlayer space, the change of mixed gangue ratio was simulated six times, specifically: Under the condition of single interlayer and fixed interlayer space, the thickness of interlayer was changed and simulated six times, and the initial mixed gangue rate-operation step change curve was obtained, and the change law of mixed gangue rate was analyzed. 1.4.

3. Under the condition of multi-layer intercalated gangue, the changes of mixed gangue ratio were simulated seven times, specifically: Under the condition of multiple layers of interlayers with fixed thickness, the spatial layer of interlayers was changed for seven simulations, and the initial mixed gangue rate-operating step number change curve was obtained, and the changing law of mixed gangue rate was obtained by analysis.

6. The intelligent coal caving method for fully mechanized caving mining of extra-thick coal seams according to claim 1 is characterized by: In step 2, the working parameters of the detector include the number of detectors to be arranged, the optimal output working voltage of the photomultiplier tube, and the size of the detector; Among them, the specific steps to determine the working parameters of the detector used in fully mechanized caving mining of complex structure and extra-thick coal seams are as follows: 2.

1. Calculate the number of detectors to be arranged, specifically: Use a blackout cloth to cover the detector light source, connect the circuit, operate the power knob to adjust the voltage, record the multimeter reading at each voltage, and then connect the oscilloscope to measure the starting current and working current. Combined with the intrinsically safe power supply manual, confirm the number of detectors to be arranged; 2.

2. Determine the optimal output operating voltage of the photomultiplier tube, specifically: Use a shading cloth to cover the photomultiplier tube, install a multimeter on the high-voltage module, measure the voltage of the photomultiplier tube, operate the voltage knob of the high-voltage module to adjust the working voltage of the photomultiplier tube, record 2 minutes of data every 10V, get 1200 data in each group, take the average value to make a line graph, and analyze to get the best output working voltage of the photomultiplier tube; 2.

3. Determine the size of the detector, which is measured on-site in the laboratory.

7. The intelligent coal caving method for fully mechanized caving mining of extra-thick coal seams according to claim 1 is characterized by: In step 3, the radiation variation law of the mixed state flow of the falling heterogeneous medium of the coal, gangue and direct roof of the complex structure and extra-thick coal seam is obtained according to the mixing law of the falling flow and the detection results of the detector. The specific steps are: 3.

1. Measure the background radiation of the coal opening environment of the fully mechanized caving working face and determine the threshold voltage of the detector, specifically: After the detector is set up in the underground production working face, the threshold voltage is adjusted upward step by step from 0 to obtain the background radiation value change diagram under different threshold voltages; 3.

2. Install a detector to confirm the threshold voltage at the coal caving opening of the fully mechanized caving working face, and carry out normal coal caving work after all debugging is completed; 3.

3. Use Matlab to process the radiation value change data detected by the detector during the coal discharge process, sort out the radiation change diagram, and analyze the radiation change law of the discharged heterogeneous medium mixed state flow.

8. The intelligent coal caving method for fully mechanized caving mining of extra-thick coal seams according to claim 1 is characterized by: In step 4, according to the radiation change law of the heterogeneous medium mixed state flow, the window closing production number is obtained to realize intelligent coal placement. The specific steps are as follows: 4.

1. Select the most representative radiation value change graph again, as shown in Figure 14; 4.

2. Use Matlab to calculate the average radiation value every 5 seconds in the radiation change diagram, and make a fitting curve diagram of the radiation value and time scatter points. According to the radiation change law of the heterogeneous mixed state flow, the window closing production number is obtained to realize intelligent coal release.

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