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

Abstract

The application discloses a kind of intelligent caving methods of super-thick coal seam fully mechanized caving, after confirming the working parameters of detector used in super-thick coal seam fully mechanized caving, the detection result of detector is combined with the caving flow mixing law of coal, gangue, immediate roof of complex structure super-thick coal seam, the radiation change law of coal, gangue, rock caving heterogeneous mixed state flow is analyzed, then the radiation change law is combined with the change data of field radiation value to obtain the window closing parameter, finally, when the average value of radiation value is more than 160cps for 5s continuous detection result in caving of working face, it is indicated that immediate roof has been caved out, at this time, workers can directly close the window after checking the environment safety, end the caving process, in the process, traditional technology and intelligent technology are effectively shared and fused, so that coal can be fully caved out in super-thick coal seam fully mechanized caving, mining is efficient and thorough, intelligent caving of super-thick coal seam top coal is realized, and resource utilization is improved.

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, its stable supply 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 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 achieve high-efficiency 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 caving of extra-thick coal seams. After confirming the working parameters of the detector used for fully mechanized caving of extra-thick coal seams, the detection results of the detector are combined with the caving flow mixing law 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 on-site radiation value change data to obtain the window closing parameter. 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 indicates that the direct roof has been caving, so that all the coal can be caving in the fully mechanized caving of extra-thick coal seams, and the mining is efficient and thorough, thereby realizing the intelligent coal caving of top coal in extra-thick coal seams and improving resource utilization to solve the above-mentioned shortcomings 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 thick coal seam;

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

[0009] Step 3, according to the falling flow mixing law and the detection result of the detector, the radiation variation law of the falling heterogeneous mixed state flow of the coal, gangue and immediate roof of the thick coal seam with complex structure is obtained;

[0010] Step 4, according to the radiation variation law of the heterogeneous mixed state flow, the window closing parameter is obtained, and the intelligent caving is realized.

[0011] The aforementioned intelligent caving method for fully mechanized caving mining of the thick coal seam, in step 1, the falling flow mixing law includes the influence law of the gangue thickness on the falling flow timing of the coal, gangue and immediate roof;

[0012] The influence law of the gangue layer spacing on the falling flow timing of the coal, gangue and immediate roof;

[0013] And the variation law of the gangue mixing rate.

[0014] The aforementioned intelligent caving method for fully mechanized caving mining of the thick coal seam, wherein the influence law of the gangue thickness on the falling flow timing of the coal, gangue and immediate roof is calculated, and the specific steps are as follows:

[0015] 1.1, different parameters are given to the coal, gangue and immediate roof;

[0016] 1.2, according to the given parameters, the influence of the gangue occurrence thickness on the falling flow timing of the coal, gangue and immediate roof is simulated, specifically:

[0017] Specifically, under the condition that the single layer gangue and the gangue spatial layer position are fixed, the gangue thickness is changed for six times, the running time of the first gangue and the first roof is obtained, and the influence law of the gangue thickness on the falling flow timing of the coal, gangue and immediate roof is analyzed.

[0018] The aforementioned intelligent caving method for fully mechanized caving mining of the thick coal seam, wherein the influence law of the gangue layer spacing on the falling flow timing of the coal, gangue and immediate roof is calculated, and the specific steps are as follows:

[0019] 1.3, according to the given parameters, the influence of the gangue layer spacing on the falling flow timing of the coal, gangue and immediate roof is simulated, specifically:

[0020] Under the condition that the multiple layer gangue and the gangue thickness are fixed, the gangue spatial layer position is changed, and the gangue layer position is marked from bottom to top, the gangue layer spacing simulation analysis is carried out, and the influence law of the gangue layer spacing on the falling flow timing of the coal, gangue and immediate roof is obtained.

[0021] The aforementioned intelligent caving method for fully mechanized caving mining of the thick coal seam, wherein the variation law of the gangue mixing rate is calculated, and the specific steps are as follows:

[0022] 1.4. In PFC3D, the mass of all particles in a certain area and their changes are recorded in real time to obtain the changing pattern of the ratio of the mass of the gangue contained in the coal at the coal outlet to the total mass during the coal discharge process, that is, the changing pattern of the mixed gangue ratio. The following steps are included:

[0023] 1.4.1. Assuming that at a certain moment there are m coal particles, n gangue particles, and a direct top particles in the designated coal caving area, the formula for calculating the mixed gangue ratio P is as follows:

[0024] M 煤 =mρ 煤 4πR 煤 3 / 3

[0025] M 矸 =nρ 矸 4πR 矸 3 / 3

[0026] M 直 =aρ 直 4πR 直 3 / 3

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

[0028] Among them, M 煤 、M 矸 、M 直 are the masses of coal particles, gangue particles and direct top particles in the designated coal caving area respectively;

[0029] 1.4.2. Under the condition of a single interlayer of gangue and a fixed interlayer space, the changes in the mixed gangue ratio were simulated six times, specifically:

[0030] Under the condition of a single layer of interlayer gangue and a fixed interlayer position, the thickness of interlayer gangue was changed and simulation was repeated six times to obtain the curve of initial mixed gangue rate-running step number, and the changing law of mixed gangue rate was obtained through analysis.

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

[0032] Under the condition of multiple layers of interlayered gangue and fixed thickness of interlayered gangue, the spatial layer of interlayered gangue was changed and simulated seven times to obtain the initial mixed gangue rate-operating step change curve, and the changing law of mixed gangue rate was obtained by analysis.

[0033] The working parameters of the detector in the intelligent caving method for fully-mechanized caving mining of the super-thick coal seam include the number of detectors, the optimal output working voltage of the photomultiplier, and the size of the detector.

[0034] The working parameters of the detector in the intelligent caving method for fully-mechanized caving mining of the super-thick coal seam include the number of detectors, the optimal output working voltage of the photomultiplier, and the size of the detector.

[0035] 2.1, the number of detectors is calculated, specifically:

[0036] The detector light source is covered with a black cloth, the circuit is connected, the voltage is adjusted by operating the power knob, the multimeter reading at each voltage is recorded, and then the starting current and working current are measured by connecting the oscilloscope, and the number of detectors is confirmed according to the intrinsically safe power supply manual.

[0037] 2.2, the optimal output working voltage of the photomultiplier is determined, specifically:

[0038] The photomultiplier is covered with a black cloth, a multimeter is installed on the high-voltage module to measure the voltage of the photomultiplier, the working voltage of the photomultiplier is adjusted by operating the high-voltage module voltage knob, 1200 data are obtained for each group by recording data every 10V for 2 minutes, and the average value is taken to make a broken line graph, and the optimal output working voltage of the photomultiplier is analyzed.

[0039] 2.3, the size of the detector is measured, specifically measured in the laboratory.

[0040] The working parameters of the detector in the intelligent caving method for fully-mechanized caving mining of the super-thick coal seam include the number of detectors, the optimal output working voltage of the photomultiplier, and the size of the detector.

[0041] 3.1, the background radiation of the caving mouth environment of the fully-mechanized caving face is measured to determine the threshold voltage of the detector, specifically:

[0042] After the detector is erected in the underground production face, the threshold voltage is adjusted step by step from 0 upwards, and the background radiation value change graph under different threshold voltages is obtained.

[0043] 3.2, the detector with the confirmed threshold voltage is installed at the caving mouth of the fully-mechanized caving face, and after the debugging is completed, the normal caving work is carried out.

[0044] 3.3, the radiation value change data detected by the detector during the caving process are processed by Matlab, the radiation change graph is arranged, and the radiation change law of the caving heterogeneous mixed state flow is analyzed.

[0045] In the aforementioned intelligent caving method for fully mechanized caving of extra-thick coal seams, in step 4, the window closing parameters are derived based on the radiation variation law of the heterogeneous medium mixed state flow to achieve intelligent caving. The specific steps are as follows:

[0046] 4.1. Select the most representative radiation value change graph again;

[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 medium mixed state flow, the window closing parameters are obtained to realize intelligent coal discharge.

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

[0049] The present invention simulates and analyzes the coal caving process in the process of top coal caving in complex structure and extra-thick coal seams, and 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 device, and adjusts the working parameters of the overall detection system. After a round of coal caving, the radiation change law of the heterogeneous mixed state flow of coal, gangue and rock caving is analyzed in combination with the caving flow mixing law and the detection results of the detector. The radiation change law is combined with the on-site 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 worker 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 all coal can be caving during the comprehensive caving mining of extra-thick coal seams, and the mining is efficient and thorough, realizing intelligent coal 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 following briefly introduces the drawings required for use in the embodiments. Obviously, the drawings described below are only some embodiments described 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 This is a simulation diagram when the thickness of the gangue is 0.5m;

[0053] Figure 3 It is a line graph of simulation results under the condition of single-layer interbedded 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 Bar chart of simulation results for interlayer spacing of interlayer;

[0056] Figure 6 Fold line chart of simulation results for change of interlayer mixing rate under single interlayer;

[0057] Figure 7 Fold line chart of simulation results for change of interlayer mixing rate under multiple interlayers;

[0058] Figure 8 Interface schematic diagram for current experiment;

[0059] Figure 9 Circuit diagram for use of intrinsic safety power supply;

[0060] Figure 10 Dark radiation change curve;

[0061] Figure 11 Background radiation value change graph under different threshold voltages;

[0062] Figure 12 Radiation value change graph during caving process;

[0063] Figure 13 Radiation value change graph during caving process after reselection;

[0064] Figure 14 Radiation average value change graph every 5 seconds. DETAILED DESCRIPTION

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

[0066] The present application provides an intelligent caving method for fully mechanized caving mining of extra-thick coal seams, as shown in Figures 1-14 The method comprises the following steps:

[0067] Step 1, calculate the caving flow mixing rule of coal, waste rock and immediate roof of the complex structure extra-thick coal seam;

[0068] The caving flow mixing rule includes the influence rule of interlayer thickness on the caving flow timing of coal, waste rock and immediate roof;

[0069] The influence rule of interlayer spacing on the caving flow timing of coal, waste rock and immediate roof;

[0070] And the change rule of interlayer mixing rate;

[0071] And PFC3D can be used to simulate and analyze the caving process during the top coal caving process of the complex structure extra-thick coal seam, so as to calculate the caving flow mixing rule;

[0072] Wherein, the influence law of the falling flow time sequence of coal, gangue and immediate roof is calculated, and the specific steps are as follows:

[0073] 1.1, different parameters of coal, gangue and immediate roof are given, and the specific steps are shown in Table 1;

[0074] Table 1

[0075]

[0076] 1.2, according to the given parameters, the influence of the thickness of the gangue on the falling flow time sequence of coal, gangue and immediate roof is simulated;

[0077] Specifically, under the condition that the single layer of gangue and the gangue space layer position are fixed, the gangue thickness is changed for six times, the running time of the first gangue and the first roof is obtained, Table 2 is prepared, and the attached Figure 3 is arranged.

[0078] Table 2

[0079]

[0080] From Table 2, the attached Figure 3 , it can be seen that under the condition that the single layer of gangue and the gangue layer position are fixed, the change of the thickness of the gangue has little effect on the time of the gangue layer entering the coal falling port;

[0081] Wherein, the influence law of the falling flow time sequence of coal, gangue and immediate roof is calculated, and the specific steps are as follows:

[0082] 1.3, according to the given parameters, the influence of the gangue layer spacing on the falling flow time sequence of coal, gangue and immediate roof is simulated;

[0083] Specifically, under the condition that the multiple layers of gangue and the gangue thickness are fixed, the gangue space layer position is changed, and the gangue layer position is marked from bottom to top, and the gangue layer spacing simulation analysis is carried out;

[0084] Wherein, as shown in the attached Figure 4 , the gangue layer position is marked from bottom to top as ①, ②, ③, ④, ⑤, ⑥, and in the simulation process, the gangue at ③, ④, ②, ⑤, ①, ⑥ is deleted in turn each time, and the coal seam is filled, the simulation results are prepared into Table 3, and the attached Figure 5 is arranged.

[0085] Table 3

[0086]

[0087]

[0088] Wherein, in this step 1.3, due to the different physical parameters of gangue and coal seam, the change of the number of gangue particles in the simulation has a slight effect on the flow timing when falling, but in actual production, this difference can be ignored, so the table 3, attached Figure 5 It can be concluded that:

[0089] Under the condition of multi-layer gangue and fixed gangue thickness, the higher the layer of the gangue layer, the longer the time it takes to enter the coal drop hole, and the time difference of the gangue of different layers entering the coal drop hole is only related to the layer spacing;

[0090] Wherein, the change rule of mixed gangue rate is calculated as follows:

[0091] 1.4, in PFC3D, the mass of all particles in a certain area and its change are recorded in real time, and the change rule of the mass ratio of gangue in coal to total mass of coal drop hole in the process of coal dropping, that is, the change rule of mixed gangue rate, is obtained, including the following steps:

[0092] 1.4.1, suppose that there are m coal particles, n gangue particles and a directly top particles in a certain area at a certain time, then the calculation formula of mixed gangue rate P is as follows:

[0093] M 煤 = m p 煤 4 p R 煤 / 3 3

[0094] M 矸 = n p 矸 4 p R 矸 / 3 3

[0095] M 直 = a p 直 4 p R 直 / 3 3

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

[0097] Wherein, M 煤 , M 矸 , M 直 are the mass of coal particles, gangue particles and directly top particles in the specified coal drop hole area respectively, which is used to evaluate the density of coal and rock particles in the specified coal drop hole area at this time, the greater the value, the more corresponding coal and rock particles in the specified coal drop hole area, on the contrary, the coal and rock particles are less, and M 煤 , M 矸 , M 直Collectively referred to as coal rock particles;

[0098] 1.4.2. Under the condition of a single interlayer of gangue and a fixed interlayer space, the changes in the mixed gangue ratio were simulated six times, specifically:

[0099] Under the condition of a single layer of interlayer gangue and a fixed interlayer position, the thickness of interlayer gangue was changed and the simulation was repeated six times to obtain the curve of initial mixed gangue rate-running step number. The results are shown in the figure below. Figure 6 As shown;

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

[0101] When the thickness of the interlayer is less than 0.4m, the interlayer is thin and the discharge of the interlayer is discontinuous, 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; after the initial peak is reached, the mixed gangue rate increases significantly, and when it rises to around 45%, it fluctuates around 45%.

[0102] When the thickness of the interlayer is greater than 0.4m, the interlayer is released continuously, and the mixed gangue rate starts to rise from 0 when the gangue is first seen, and then fluctuates within a certain range. After the initial peak, the mixed gangue rate 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 the mixed gangue ratio were simulated seven times, specifically:

[0104] Under the condition of multiple layers of interlayer gangue and fixed thickness of interlayer gangue, the interlayer gangue spatial layer 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 conditions of multiple layers of interlayered gangue and fixed thickness of interlayered gangue, the mixing rules of each layer of interlayered gangue are the same as those of a single layer of interlayered gangue, that is, the interlayered gangue layer is released continuously, 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 layer 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. After reaching the peak for the first time, the mixed gangue rate increases significantly, and when it rises to around 45%, it fluctuates around 45%.

[0107] In step 1, by using PFC3D to simulate and analyze the caving process of the complex structure thick coal seam during the top coal caving process, the caving flow mixing law of coal, gangue and immediate roof of the complex structure thick coal seam is obtained, it can be seen that in the process of underground coal caving, coal, gangue and rock will be caved according to the spatial layer sequence, and the mixing has regularity, which verifies the feasibility of the application, through the pfc numerical simulation software, the internal situation of the caving flow mixing of coal, gangue and immediate roof can be observed, and for the analysis of the simulation results and internal phenomena, the radiation change law of the caving heterogeneous mixed state flow of coal, gangue and immediate roof and the internal phenomenon of the occurrence of the law can be speculated.

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

[0109] Among them, the working parameters of the detector include the arrangement number of the detector, the optimal output working voltage of the photomultiplier tube, and the size of the detector;

[0110] And the specific steps of determining the working parameters of the detector used in the fully mechanized caving mining of the complex structure thick coal seam are:

[0111] 2.1, calculate the arrangement number of the detector, specifically: cover the detector light source with a light shield, connect the circuit, adjust the voltage by operating the power knob, record the multimeter reading at each voltage, then connect the oscilloscope to measure the starting current and working current, combine the intrinsically safe power supply manual, and the specific results are shown in the attached Figure 8 ;

[0112] As shown in the attached Figure 8 , the starting current is about 150mA, and the working current of the overall 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 during starting should not exceed 1.95A, and the optimal working state of the power supply during normal working should ensure that the total current is about 1000mA;

[0117] And in step 2.1, the normal working current of a device is about 100mA, and the starting current is about 150mA, so the maximum number of detectors that can be carried by a intrinsically safe power supply of this type is 10, and the maximum number of detectors that can be carried by a intrinsically safe power supply of this type is 13 according to the overcurrent protection, and finally the maximum number of detectors that can be carried by a intrinsically safe power supply of this type 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. Figure 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. During measurement, the voltage is set to 10-14V, and the voltage is increased by 0.1V. The starting current, operating current, and high-voltage module voltage are measured at different voltages.

[0120] 2.2. Determine the optimal output voltage of the photomultiplier tube. Specifically, cover the photomultiplier tube with a blackout 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 data for 2 minutes every 10V, and obtain 1200 data for each group. Take the average value and make a line graph. Figure 10 As shown;

[0121] The circuit diagram follows that in step 2.1. The maximum voltage the photomultiplier tube can withstand, as determined by the manual, is 1250V. Exceeding 1250V may damage the device. Preliminary measurements show that the dark current output is almost zero when the voltage is less than 1000V. This indicates that the voltage is too low 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 Figure 10 It can be seen that before 1120V, the dark radiation increases slowly with the increase of voltage, and the upward trend gradually increases. After 1120V, the rising slope of the curve is the largest and basically fixed. Therefore, in order to maximize the operating voltage of the photomultiplier tube and minimize the influence of dark current, the operating 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, the appropriate 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 during operation. The circuit board has the function of controlling the voltage provided to the photomultiplier tube by the high-voltage module and transmitting data.

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

[0126] In this step 2.3, the minimum size required by its detector is 25x20x5cm, which is measured in the laboratory site;

[0127] And when used in the mine, considering the influence of background radiation, an aluminum plate shield is needed to be installed. In order 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 size detector as much as possible without affecting the coal caving. In order to protect the detector from being damaged by the coal and gangue, the detector is installed on the support shelter beam. When the plugboard swings, it does not affect the detector. When the coal is caved and the window is closed, the detector is always protected by the shelter beam. During the caving process, the detection surface is opposite to the caving coal gangue;

[0128] After checking the size specification of the ZFY18000 / 28 / 53D hydraulic support shelter beam used in the working face of Longwanggou Coal Mine, it is calculated that the maximum space that can be accommodated by the support is 45x35x10cm. In actual installation, whether the on-site installation operation is convenient is considered, and a flexible space is left for the movement of the support. The size of the detector is determined to be 42.5x30x8cm.

[0129] In step 2, a photomultiplier tube is selected as the main detection device. The working parameters of the overall detection system are adjusted, which is used as the final intelligent caving monitoring device to ensure that the detector can safely and reliably obtain the radiation value-time curve during caving in the mine.

[0130] Step 3, according to the caving flow mixing law and the detection results of the detector, the radiation change law of the caving heterogeneous mixed state flow of coal, gangue and immediate roof in the complex structure and thick coal seam is obtained. The specific steps are as follows:

[0131] 3.1, measure the background radiation of the caving opening environment of the fully mechanized caving face, and determine the threshold voltage of the detector. Specifically:

[0132] After the detector is erected in the underground production working face, the threshold voltage is adjusted step by step from 0 upwards, and the background radiation value change graph under different threshold voltages is obtained;

[0133] And in this step 3.1, the detector will filter the background radiation with different energy according to the voltage change. The specific results are shown in the attached Figure 11 ;

[0134] As shown in the attached Figure 11 , 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 changes little with the increase of the threshold voltage. Combined with the economic principle, the threshold voltage value 0.3V is selected. It can be predicted that during the caving process, the radiation value of the detector should be around 130cps only when the coal is caved;

[0135] In this 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 crucial to correctly set the working voltage of the detector to ensure that the detector can operate under optimal conditions, while avoiding excessive voltage that can cause equipment damage, when setting the working voltage, it should be ensured that the voltage value is higher than the threshold voltage to ensure that the detector can effectively respond to signals;

[0136] Background radiation refers to the natural radiation that always exists in the environment, which is composed of radiation produced by elements in nature and human activities, the size and variation of background radiation have an impact on the change of radiation value during coal caving, therefore, it is necessary to measure and filter the background radiation;

[0137] The relationship between the threshold voltage and the background radiation is reflected in whether the detector can distinguish the signal from the noise caused by the background radiation, increasing the threshold voltage can reduce false signals or interference caused by the background radiation, if the threshold voltage is set too low, the background radiation may cause the detector to generate signals higher than the threshold, which will make the detector mistakenly record these background events as valid events, at the same time, if the threshold voltage is set too high, real event signals may not be detected because they fail to reach the new high threshold if their intensity is close to that of the background radiation;

[0138] 3.2, install the detector with confirmed threshold voltage at the caving mouth of the fully mechanized caving face, and carry out normal caving work after all debugging is completed;

[0139] 3.3, use Matlab to process the radiation value change data detected by the detector during caving, sort out the radiation change graph, and analyze the radiation change law of the mixed state flow of caving and falling;

[0140] Due to the large number of radiation change graphs and their high similarity, the most representative radiation change graph is selected, and the results are shown in the attached Figure 12 ;

[0141] According to the mixing law of coal, gangue and rock obtained by numerical simulation in step 1, combined with the attached Figure 12 , the analysis of the measured radiation value change data in the underground is carried out, and the radiation change law of the mixed state flow of caving and falling is obtained, which has the following three cases:

[0142] (1) The first layer of gangue enters the caving mouth: the layer of gangue is thin, and there will be a discontinuous state in the whole process of caving, only a small amount of gangue is caved in the process of 90-110s, and the radiation level is the same as that when only coal is caved;

[0143] The variation of the radiation value at this time is: from the beginning of the gangue, the radiation value rises rapidly from 130 cps to 150 cps, and after a period of emission, the radiation value is disconnected and immediately returns to normal level, and the overall radiation value fluctuates in the range of 130-150 cps;

[0144] (2) The second layer of gangue enters the coal discharging port: the layer of gangue is thicker, and in the overall process of emission, it is in a continuous state;

[0145] The variation of the radiation value is: from the beginning of the gangue, the radiation value rises rapidly from 130 cps to 150 cps, and after reaching 150 cps, it fluctuates around 150 cps until the radiation value decreases to normal level after complete emission;

[0146] (3) The immediate roof enters the coal discharging port: after the immediate roof enters the coal discharging port, the mixed gangue rate rapidly rises to about 45%, so the radiation value changes more quickly and with a larger amplitude than when the gangue is mixed;

[0147] The variation of the radiation value is: after the initial roof is seen in the coal discharging port, the radiation value rises linearly from 130 cps to about 160 cps, and then fluctuates within a certain range around 160 cps.

[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, and thus the preparation work is completed. At this time, the detector is turned on to determine that the radiation value change detection is normal, and then the coal emission operation is performed. After a round of coal emission, all detector data is read to obtain a set of radiation value-time variation curves during the coal emission process. The data is filtered using MATLAB to obtain a fitted radiation value variation curve that is easy to observe. The radiation value variation curve is analyzed in combination with the emission and flow mixing law in step 1 to obtain the radiation variation law of the coal, gangue, and rock emission and flow mixing state stream.

[0149] Step 4: According to the radiation variation law of the heterogeneous mixed state stream, the window closing parameter is obtained to realize intelligent coal emission. The specific steps are as follows:

[0150] 4.1: Again select one of the most representative radiation value variation graphs, as shown in the attached Figure 13 ;

[0151] 4.2: Calculate the average radiation value every 5 seconds in the radiation variation graph using Matlab to make a fitted curve graph of the radiation value and time scatter points. According to the radiation variation law of the heterogeneous mixed state stream, the window closing parameter is obtained to realize intelligent coal emission.

[0152] The fitted curve graph is specifically shown in the attached Figure 14 , and the attached Figure 13 and 14It can be seen that when the gangue layer enters the coal discharging opening, the radiation value is not more than 160 cps on average, and when the direct roof enters the coal discharging opening, the radiation value is more than 160 cps on average, so the window can be closed when the radiation value is more than 160 cps for 5s continuously;

[0153] In step 4, by combining the radiation change rule obtained in step 3 with a field radiation value change data, it is analyzed that the average radiation value of every 5 seconds may be different when the gangue layer is discharged and the direct roof is discharged, and the assumption is verified by Matlab calculation, and finally the window is closed when the radiation value is more than 160 cps for 5s continuously, which is verified by other data collected in the field, further proving the effectiveness of the method, that is, when the coal is discharged in the working face, first ensure that the detector normally obtains the radiation value change data, and then perform the coal discharging operation, when the average value of the detection result is more than 160 cps for 5s continuously, the detector warns the worker that the direct roof has been discharged, and the worker checks the environment safety and then closes the window, so as to realize intelligent coal discharging.

[0154] In summary

[0155] The present application simulates and analyzes the falling process of the complex structure and thick coal seam during the top coal caving process, obtains the falling flow mixing rule of coal, gangue and direct roof of the complex structure and thick coal seam, selects a photomultiplier as a main detection device, adjusts the working parameters of the overall detection system, after a round of coal discharging is completed, combines the falling flow mixing rule and the detection result of the detector, analyzes the radiation change rule of the falling flow mixing state of coal, gangue and rock, combines the radiation change rule with the field radiation value change data to obtain the window closing parameter, and finally confirms that when the average value of the detection result is more than 160 cps for 5s continuously, the direct roof has been discharged, at this time, the worker can directly close the window after checking the environment safety, and ends the coal discharging process. In this process, the traditional technology and intelligent technology are effectively shared and integrated, so that the coal can be completely discharged during the fully mechanized mining of the thick coal seam, the mining is efficient and complete, the intelligent coal caving of the thick coal seam is realized, the resource utilization rate is improved, and the technical standard of the method is unified, the difficulty of data sharing and integration of the traditional technology and intelligent technology is reduced, the rational exploitation and utilization of coal resources are realized, the digital transformation of the coal industry is accelerated, the strategy and path of intelligent construction are continuously optimized, and the green and low-carbon development plays an important role.

[0156] The above only describes certain exemplary embodiments of the present application in a descriptive manner, without doubt, for ordinary skilled in the art, the described embodiments can be modified in various ways without departing from the spirit and scope of the present application. Therefore, the above figures and description are illustrative in nature and should not be construed as limiting the scope of the claims of the present application.

Claims

1. An intelligent coal caving method for fully mechanized caving mining of extra-thick coal seams, characterized by comprising the following steps: Step 1: Calculate the mixing law of coal, gangue and direct roof in the complex structure and thick coal seam; 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; 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 pattern of mixed waste ratio; And 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 interbedded gangue on the timing of the fall and flow of coal, gangue and direct roof. Specifically, under the condition of a single layer of interlayer gangue and a fixed interlayer position, the thickness of the interlayer gangue was changed and simulated six times to obtain the running time of the first gangue and the first roof. The influence of the thickness of the interlayer gangue on the falling flow sequence of coal, gangue and direct roof was analyzed. And calculate the changing law of mixed waste rate. The specific steps are as follows: 1.

4. In PFC3D, the mass of all particles in a certain area and their changes are recorded in real time to obtain the changing pattern of the ratio of the mass of the gangue contained in the coal at the coal outlet to the total mass during the coal discharge process, that is, the changing pattern of the mixed gangue ratio. The following steps are included: 1.4.

1. Assuming that at a certain moment there are m coal particles, n gangue particles, and a direct top particles in the designated coal caving area, the formula for calculating the mixed gangue ratio P is as follows: M 煤 =mρ 煤 4πR 煤 3 / 3 M 矸 =nρ 矸 4πR 矸 3 / 3 M 直 =aρ 直 4πR 直 3 / 3 P=(M 矸 +M 直 ) / (M 煤 +M 矸 +M 直 ) Among them, M 煤 、M 矸 、M 直 are the masses of coal particles, gangue particles and direct top particles in the designated coal caving area respectively; 1.4.

2. Under the condition of a single interlayer of gangue and a fixed interlayer space, the changes in the mixed gangue ratio were simulated six times, specifically: Under the condition of a single layer of interlayer gangue and a fixed interlayer position, the thickness of interlayer gangue was changed and simulation was repeated six times to obtain the curve of initial mixed gangue rate-running step number, and the changing law of mixed gangue rate was obtained through analysis. 1.4.

3. Under the condition of multi-layer intercalated gangue, the changes of the mixed gangue ratio were simulated seven times, specifically: 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, and the change law of mixed gangue rate was obtained through analysis. Step 2: Determine the working parameters of the detector used in fully mechanized caving mining of complex and thick coal seams; In step 2, the operating parameters of the detector include the number of detectors arranged, the optimal output operating voltage of the photomultiplier tube, and the size of the detector; The specific steps to determine the working parameters of the detector used in fully mechanized top-coal caving mining of complex and 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 an oscilloscope to measure the starting current and working current. Combined with the instruction manual of the intrinsically safe power supply, confirm the number of detectors to be arranged; 2.

2. Determine the optimal output operating voltage of the photomultiplier tube, specifically: Use a blackout 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, and obtain 1200 data in each group. Take the average value to make a broken line graph, and analyze to obtain the optimal output working voltage of the photomultiplier tube; 2.

3. Determine the size of the detector, specifically by on-site measurement in the laboratory; Step 3: Based on the falling flow mixing law 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 in the complex structure and extra-thick coal seam is obtained; Step 4: Based on the radiation change law of the heterogeneous medium mixed state flow, the window closing parameters are 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 in that: The influence of the spacing between interlayers of gangue on the flow sequence of coal, gangue and direct roof is calculated as follows: 1.

3. Based on the given parameters, simulate the effect of the spacing between interlayers on the flow sequence of coal, gangue, and direct roof. Specifically: Under the condition of multiple layers of interlayered gangue and fixed thickness of interlayered gangue, the interlayered gangue spatial layer is changed and the interlayered gangue layers are marked from bottom to top. The interlayered gangue spacing simulation analysis is carried out to obtain the influence of the interlayered gangue spacing on the falling flow sequence of coal, gangue and direct roof.

3. 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, based on the falling flow mixing law 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 in the complex structure and extra-thick coal seam is obtained. The specific steps are: 3.

1. Measure the background radiation of the coal caving mouth environment of the fully mechanized caving working face and determine the threshold voltage of the detector, specifically: After setting up the detector in the underground production working face, the threshold voltage is adjusted 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, compile the radiation change diagram, and analyze the radiation change law of the discharged heterogeneous medium mixed state flow.

4. 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, based on the radiation variation law of the heterogeneous mixed state flow, the window closing parameters are obtained to achieve intelligent coal placement. The specific steps are as follows: 4.

1. Select the most representative radiation value change graph again; 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 medium mixed state flow, the window closing parameters are obtained to realize intelligent coal discharge.

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