Coal seam goaf sealing method

Abstract

The application provides a coal seam goaf sealing method, which is used in coal seam mining underground and includes a working area, a goaf, a lower coal seam, a mining working face, an air inlet and return air lane and an air return tunnel. The lower coal seam is located at the lower part of the goaf. The sealing method comprises the following steps: before the lower coal seam is mined, sol is injected into the goaf through the air return tunnel in the working area to build a plurality of gel isolation sections; during the mining of the lower coal seam, when the goaf perpendicular to the strike of the lower coal seam collapses, a detection hole is opened in the horizontal direction through the air inlet and return air lane; the natural cavity is determined through the detection hole, and the state of the gel isolation section and the goaf is monitored through the natural cavity; when the collapse and / or collapse cavity in the goaf is monitored, sol is injected into the goaf.

Description

Technical Field

[0001] This application relates to the field of coal mine safety technology, and in particular to a method for sealing coal seam goaf. Background Technology

[0002] During coal mining, there are hazardous sources such as residual coal and flammable gases in the goaf. When the goaf leaks air, it will get enough oxygen, which will cause the residual coal in the goaf to oxidize, thus greatly increasing the probability of spontaneous combustion in the goaf, seriously affecting the work safety of underground workers.

[0003] Among various types of coal seams, steeply dipping coal seams are widely mined, mostly in the form of coal seam clusters. Due to their large dip angle, the roof pressure manifestation pattern is complex, making mining difficult and resulting in low mechanization, thus heavily relying on manual labor. Furthermore, the complex development of overlying fissures in these coal seams leads to a complex ventilation system, making roof and goaf management challenging. Additionally, the presence of flammable and explosive gases in old goafs poses a significant risk of spontaneous combustion and explosion if air leakage occurs. These leaked flammable and explosive gases can then flow through fissures in the coal and rock strata to new mining areas, threatening the safety of workers operating in these new areas. Summary of the Invention

[0004] In view of this, this application provides a method for sealing coal seam goaf, which can prevent air leakage in the goaf in advance and seal it in time after the leakage occurs, thereby reducing the possibility of spontaneous combustion in the goaf due to air leakage, and thus protecting the underground coal mine.

[0005] This application provides a method for sealing a coal seam goaf, used in underground coal seam mining operations. The underground coal mine includes a working area, a goaf, a lower coal seam, a longwall face, intake and return airway, and a return airway. The lower coal seam is located below the goaf. The sealing method includes: Before the lower coal seam is mined, sol is injected into the goaf through the return air roadway in the working area to construct multiple gel isolation sections. During the mining of the lower coal seam, when a goaf occurs perpendicular to the strike of the lower coal seam, a detection hole is opened in the horizontal direction through the intake and return airway. Natural cavities are identified through the detection holes, and the state of the gel isolation section and goaf is monitored through the natural cavities. When a collapse and / or a collapse cavity is detected in the goaf, the sol is injected into the goaf.

[0006] In one possible implementation, the injection of sol into the goaf via the return air roadway to construct multiple gel isolation sections includes: Multiple injection holes are opened in the goaf through the return air roadway, and a drill pipe is installed in the injection hole. The drill pipe is fixed around the perimeter with a cementitious material. The sol is prepared according to a preset first ratio, and injected into the goaf area through the plurality of injection holes using a sol injection device. The sol is shut down when the sol injection device vibrates and / or the sol flows out of the injection holes.

[0007] In one possible implementation, the cementing material includes cement, lime, or gypsum.

[0008] In one possible implementation, the preset first ratio k1 satisfies: 1:7 ≤ k1 ≤ 1:5.

[0009] In one possible implementation, the height h of the injection hole satisfies: 1cm ≤ h ≤ 2cm; The diameter r of the injection hole satisfies: 2cm≤r≤4cm.

[0010] In one possible implementation, the step of identifying natural cavities through the detection holes and monitoring the state of the gel isolation section and the goaf through the natural cavities, and when a collapse and / or a collapse cavity is detected in the goaf, injecting the sol into the goaf, includes: A detection element is installed in the detection hole, and a monitoring device is installed in the work area. The detection element is communicatively connected to the monitoring device, and the natural cavity is detected using the detection element and the monitoring device. After determining the existence of the natural cavity based on the detection element and the monitoring equipment, a monitoring component is set in the natural cavity to obtain the status data of the gel isolation section and the goaf, and a communication connection is established between the monitoring component and the monitoring equipment. The monitoring device receives the status data and issues an alarm signal when the status data exceeds the corresponding preset safety threshold, and injects the sol into the goaf area based on the alarm signal.

[0011] In one possible implementation, the monitoring component includes a temperature sensing element, a pressure sensing element, and a detection element, all of which are communicatively connected to the monitoring device.

[0012] In one possible implementation, the status data includes real-time temperature data and real-time pressure data, the preset safety threshold includes a temperature safety threshold and a pressure safety threshold, and the monitoring device is capable of: Acquire the real-time temperature data and the real-time pressure data, and compare the real-time temperature data with the temperature safety threshold and the real-time pressure data with the pressure safety threshold, respectively. The alarm signal is issued based on the real-time temperature data exceeding the temperature safety threshold and / or the real-time pressure data exceeding the pressure safety threshold.

[0013] In one possible implementation, injecting the sol into the goaf based on the alarm signal includes: Based on receiving the alarm signal, the sol is prepared, and the sol is drawn in by the injection equipment and injected into the goaf through the detection hole; If the dispensing equipment vibrates and / or the sol flows out of the detection hole, shut down the dispensing equipment. After determining the solidification effect of the sol injected into the goaf, and confirming that the collapse cavity formed by the collapse has been sealed and / or the gel isolation section has returned to a stable state, the pipeline between the sol injection equipment and the detection hole is removed.

[0014] In one possible implementation, the sol includes a coagulant made from dry materials and water in a preset second ratio, where the second ratio k2 satisfies: 1:5 ≤ k2 ≤ 1:3.

[0015] Thus, the coal seam goaf sealing method provided in this application effectively prevents flammable and explosive gases from leaking into the working area by pre-injecting sol into the goaf before the lower coal seam is mined, forming multiple gel isolation sections and improving the safety of mining operations. During the mining of the lower coal seam, when a goaf collapse occurs, workers promptly monitor the state of the gel isolation sections and the goaf through detection holes. Once a collapse or the existence of a collapse cavity is confirmed, sol is immediately injected to fill it, preventing secondary collapse or sudden gas outbursts. This sealing method combines preventative sealing with dynamic detection and repair, ensuring continuous production at the longwall face while reducing the risk of flammable gas leakage. It reduces operational difficulty while also possessing good adaptability and safety.

[0016] The above description is only an overview of the technical solution of this application. In order to better understand the technical means of this application and to implement it in accordance with the contents of the specification, and to make the above and other objects, features and advantages of this application more obvious and understandable, the following are specific embodiments of this application. Attached Figure Description

[0017] The accompanying drawings, which are included to provide a further understanding of this application and form part of this application, illustrate exemplary embodiments and are used to explain this application, but do not constitute an undue limitation of this application. In the drawings: Figure 1 This illustration shows a schematic diagram of the sealing structure of a coal seam goaf sealing method according to an embodiment of this application; Figure 2 This illustration shows one of the flowcharts of a coal seam goaf sealing method according to an embodiment of this application; Figure 3 This is a second schematic flowchart of a coal seam goaf sealing method according to an embodiment of this application.

[0018] Explanation of reference numerals in the attached figures: 10-Underground coal mine, 101-Gel isolation section, 102-Goaf, 103-Return airway, 104-Long-running face, 105-Gel injection hole, 106-Single-ended roadway, 107-Detection hole. Detailed Implementation

[0019] The technical solutions of the embodiments of this application will be clearly described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of this application. All other embodiments obtained by those skilled in the art based on the embodiments of this application are within the scope of protection of this application.

[0020] The terms "first," "second," etc., used in the specification and claims of this application are used to distinguish similar objects and not to describe a specific order or sequence. It should be understood that such use of data can be interchanged where appropriate so that embodiments of this application can be implemented in orders other than those illustrated or described herein, and the objects distinguished by "first," "second," etc., are generally of the same class and the number of objects is not limited; for example, a first object can be one or more. Furthermore, in the specification and claims, "and / or" indicates at least one of the connected objects, and the character " / " generally indicates that the preceding and following objects are in an "or" relationship.

[0021] The coal seam goaf sealing method provided in this application will be described in detail below with reference to the accompanying drawings and through specific embodiments and application scenarios. Unless otherwise specified, the following embodiments and features can be combined with each other.

[0022] This application provides a method for sealing coal seam goaf, used in underground coal seam mining operations, such as... Figure 1As shown, the underground coal mine 10 includes a goaf 102, a lower coal seam, a longwall face 104, intake and return airway roadways, and a return air roadway 103. The lower coal seam is located below the goaf 102. The entity responsible for implementing the goaf sealing method can be the workers operating underground in the coal mine 10, such as... Figure 2 As shown, the sealing method for coal seam goaf 102 includes: Step 201: Before the lower coal seam is mined, workers inject sol into the goaf 102 through the return air roadway 103 in the work area to construct multiple gel isolation sections 101.

[0023] Workers drilled multiple boreholes into the goaf 102 in the return air roadway 103 and injected sol into the goaf 102 through these boreholes. After the sol solidified, it formed gel isolation sections 101 in a direction perpendicular to the strike of the lower coal seam. These multiple gel isolation sections 101 effectively prevented flammable and explosive gases from leaking from the goaf 102 into the work area. These flammable and explosive gases could be methane, CO, or CH4.

[0024] Step 202: During the mining of the lower coal seam, when the goaf 102 perpendicular to the direction of the lower coal seam collapses, the workers open a detection hole 107 in the horizontal direction through the intake and return airway.

[0025] During the mining of the lower coal seam, the workers need to constantly observe the situation of the goaf 102 above the lower coal seam. When the goaf 102 collapses, the workers immediately evacuate. After the goaf 102 stops collapsing, the workers use the intake and return airways to open a probe hole 107 in the horizontal direction into the goaf 102.

[0026] Step 203: The staff identifies the natural cavity through the detection hole 107 and monitors the state of the gel isolation section 101 and the goaf 102 through the natural cavity. When a collapse and / or a collapse cavity is detected in the goaf 102, the staff injects sol into the collapse cavity.

[0027] The goaf 102 includes natural cavities and collapse cavities. Natural cavities are naturally formed, relatively stable cavities within the goaf 102, while collapse cavities are formed due to collapses in the goaf 102, and their structure is less stable than that of natural cavities. Workers probe the goaf 102 through the probe hole 107. When a natural cavity is detected in the goaf 102, the condition of the gel isolation section 101 and the goaf 102 is monitored through the natural cavity. Once the presence of a collapse cavity is confirmed through the probe hole 107, sol is immediately injected into the collapse cavity to fill it.

[0028] Thus, the coal seam goaf 102 sealing method provided in this application effectively prevents flammable and explosive gases from leaking into the working area by pre-injecting sol into the goaf 102 to form multiple gel isolation sections 101 before the lower coal seam is mined, thereby improving the safety of mining operations. During the mining of the lower coal seam, when the goaf 102 collapses, workers promptly monitor the status of the gel isolation sections 101 and the goaf 102 through the detection holes 107. Once a collapse is confirmed or a collapse cavity is confirmed, sol is immediately injected to fill it, preventing secondary collapse or sudden gas outbursts. This sealing method combines preventative sealing with dynamic detection and repair, ensuring continuous production of the longwall face 104 while reducing the risk of flammable gas leakage. It reduces operational difficulty while also possessing good adaptability and safety.

[0029] In some embodiments, such as Figure 3 As shown, step 201 can be achieved through steps 2011 to 2012: In step 2011, workers opened multiple injection holes 105 in the goaf 102 through the return air roadway 103, and installed drill pipes in the injection holes 105, with the drill pipes fixed around the perimeter using cementitious material.

[0030] Workers drill multiple injection holes 105 in the return air roadway 103 into the goaf 102. Before injecting the adhesive into the goaf 102, the workers place the drill pipe into the injection hole 105 and completely seal the injection hole 105 with a gelling material. Preferably, the injection holes 105 can be drilled at equal intervals in the return air roadway 103, with an opening angle of 5° to allow the sol to smoothly enter the goaf 102 and form a stable gel isolation section 101. The length of the drill pipe can be a one-inch PVC pipe, PE pipe, or PPR pipe.

[0031] In step 2012, the staff prepares the sol according to the preset first ratio and injects the sol into the goaf 102 through multiple injection holes 105 using the injection equipment. If the injection equipment vibrates and / or the sol flows out of the injection holes 105, the staff shuts down the injection equipment.

[0032] The glue injection equipment can be a pneumatic glue injection pump. During the process of injecting the sol prepared according to the first ratio into the goaf 102 through the glue injection hole 105 using the glue injection equipment, when the glue injection equipment vibrates due to pressure buildup or the sol flows out of the glue injection hole 105, it means that the amount of sol injected into the goaf 102 has reached the amount of sol required to construct the gel isolation section 101. At this time, the operator can turn off the glue injection equipment and remove it from the glue injection hole 105.

[0033] In the above embodiment, by opening injection holes 105 at equal intervals with an elevation angle of 5° in the return air roadway 103 and pre-embedding drill pipes, and using cementing material to seal the injection holes 105 and drill pipes, the stability of the injection channel and the directionality of the sol injection are ensured, effectively preventing grout leakage during the grouting process. Workers accurately control the injection endpoint based on visual signals such as equipment vibration or grout return from the injection hole 105, avoiding over-grouting or under-grouting, and ensuring the continuity and density of the gel isolation section 101. This method is simple to operate and reliable in sealing, improving injection efficiency and construction quality while reducing material waste and operational risks, providing a more refined and controllable technical guarantee for preventing flammable gas leakage in the goaf 102.

[0034] In some embodiments, the cementing material includes cement, lime, or gypsum.

[0035] Specifically, a cementitious material fills the annular pores between the outer wall of the drill pipe and the return airway 103 to fix the drill pipe, thereby allowing the sol to flow through the drill pipe to the designated location and preventing the sol from flowing back into the return airway 103 from the gap between the drill pipe and the injection hole 105 during injection. Preferably, cement can be used as the cementitious material to form a rigid connection between the drill pipe and the hole wall of the injection hole 105, allowing the drill pipe to maintain the predetermined angle at the designated position for a long period of time.

[0036] Because the cementitious material effectively fills the annular pores between the outer wall of the drill pipe and the wall of the injection hole 105, forming a stable and rigid fixation and seal for the drill pipe, it effectively prevents the molten adhesive from flowing back along the pipe wall gaps to the return airway 103 during the injection of adhesive into the goaf 102. This ensures that the molten adhesive is accurately injected into the designated location in the goaf 102 along a predetermined path. The rigid connection formed after the cement and other materials have solidified allows the drill pipe to maintain a preset elevation angle and spatial posture for a long time, thereby maintaining the construction accuracy and structural stability of the gel isolation section 101. The above embodiment effectively improves the reliability of adhesive injection and the quality of sealing while using lower construction costs, and reduces the cost and safety risks of slurry return treatment.

[0037] In some embodiments, the preset first ratio k1 satisfies: 1:7≤k1≤1:5.

[0038] Specifically, when the goaf 102 has well-developed fractures, large air leakage channels, or requires rapid sealing, a k1:5 ratio is used. This ratio results in a higher sol concentration and shorter initial setting time, enabling rapid formation of the gel isolation section 101 and preventing significant sol loss. When the air leakage channels are smaller, requiring sol diffusion to more distant areas or filling fine fractures, a k1:7 ratio is used. This ratio provides better sol flowability and a larger diffusion radius, effectively filling the complex voids in the goaf 103. Under normal conditions, a k1:6 ratio can be used, balancing gel flowability and setting speed. Determining the sol preparation ratio based on the specific conditions of the goaf 103 effectively improves the efficiency of constructing the gel isolation section 101, while also enhancing the adaptability and reliability of the constructed gel isolation section 101.

[0039] In some embodiments, the height h of the injection hole 105 satisfies: 1cm≤h≤2cm; the diameter r of the injection hole 105 satisfies: 2cm≤r≤4cm.

[0040] Preferably, the height of the injection hole 105 can be set to 1.5cm and the diameter of the injection hole 105 can be set to 3cm, so that the sol can form a continuous and stable gel isolation section 101 in the goaf 102, thereby completely blocking the channel for the sudden surge of flammable gas and improving the safety of workers operating in the coal mine 10.

[0041] In some embodiments, step 203 can be implemented by steps 2031 to 2033: Step 2031: The staff sets up a detection element in the detection hole 107 and sets up a monitoring device in the work area. The detection element and the monitoring device are connected in communication. The detection element and the monitoring device are used to detect the natural cavity.

[0042] The detection element can be a borehole inspection device. The borehole inspection device is connected to the monitoring equipment. When the detection element is set in the detection hole 107, the staff can obtain the specific situation in the goaf 102 through the monitoring equipment, and thus determine whether there are natural cavities in the goaf 102.

[0043] Step 2032: After confirming the existence of a natural cavity based on the detection elements and monitoring equipment, the staff sets up a monitoring component in the natural cavity to obtain status data and establishes a communication connection between the monitoring component and the monitoring equipment.

[0044] Once the staff determines that there is a natural cavity in the goaf 102 through detection elements and monitoring equipment, the monitoring components can be set up inside the natural cavity because the structure of the natural cavity is relatively stable, so as to monitor the status of the goaf 102 and the gel isolation section 101.

[0045] Step 2033: The monitoring equipment receives status data and issues an alarm signal when the status data exceeds the corresponding preset safety threshold. Based on the alarm signal, the staff injects sol into the goaf 102.

[0046] The monitoring equipment receives status data of the goaf 102 and gel isolation section 101 obtained by the monitoring components to determine the stability of the goaf 102 and gel isolation section 101. When the goaf 102 collapses or the gel isolation section 101 is subjected to excessive pressure, the monitoring equipment can issue an alarm signal. After receiving the alarm signal, the staff will immediately seal the collapse cavity caused by the collapse or reinforce the gel isolation section 101 which is in an unstable state so that the goaf 102 can be restored to a relatively stable state.

[0047] The above embodiments, by using detection elements in conjunction with monitoring equipment, enable workers to remotely acquire images of the interior of the goaf 102 using detection elements such as borehole sights, thereby determining the existence and location of natural cavities and avoiding blind grouting or direct entry of personnel into dangerous areas. After confirming the location of the natural cavity, monitoring components are deployed within the natural cavity to collect real-time status data of the goaf 102. When the status data exceeds a safety threshold, the monitoring equipment automatically issues an alarm signal, allowing workers to promptly seal the collapsed cavity or reinforce the unstable gel isolation section 101. The method provided by the above embodiments effectively reduces the risks of manual inspections while improving the timeliness and targeting of sealing operations, thereby ensuring the long-term stability and safety of the goaf 102 during the mining of the lower coal seam.

[0048] In some embodiments, the monitoring component includes a temperature sensing element, a pressure sensing element, and a detection element, all of which are communicatively connected to the monitoring device.

[0049] The temperature sensing element can be a temperature sensor, and the pressure sensing element can be a pressure sensor. Specifically, after determining the location of the natural cavity using the detection element, the detection element can be placed inside the natural cavity. Then, the temperature sensing element and the pressure sensing element are placed inside the natural cavity. The positions of the temperature sensing element and the pressure sensing element in the natural cavity are adjusted using the detection element initially placed in the natural cavity. This allows the monitoring component to comprehensively monitor the gel isolation section 101 in the goaf 102 and whether a collapse has occurred. The temperature data, pressure data, and image data acquired by the monitoring component can be transmitted to the monitoring equipment in real time, enabling personnel to gain a comprehensive understanding of the situation in the goaf 102 through the monitoring equipment.

[0050] In some embodiments, the status data includes real-time temperature data and real-time pressure data, the preset safety thresholds include temperature safety thresholds and pressure safety thresholds, and the monitoring device can perform steps 301 to 302: Step 301: The monitoring equipment acquires real-time temperature data and real-time pressure data, and compares the real-time temperature data with the temperature safety threshold and the real-time pressure data with the pressure safety threshold, respectively.

[0051] The temperature sensing element and the pressure sensing element can respectively acquire real-time temperature data and real-time pressure data in the goaf 102, and send the real-time temperature data and real-time pressure data to the monitoring equipment. The monitoring equipment is pre-configured with temperature safety thresholds and pressure safety thresholds. When the monitoring equipment receives real-time temperature data and real-time pressure data, it can compare them with the temperature safety thresholds and pressure safety thresholds.

[0052] Preferably, staff can also establish a database related to the goaf 102 on the monitoring equipment, and record the acquired real-time temperature and pressure data in Excel format, and then use numerical analysis software to construct data visualization graphs of temperature and pressure respectively.

[0053] Before monitoring the gel isolation segment 101, staff can also import previously saved historical data about the gel isolation segment 101 into the monitoring equipment as reference data for changes in the state of the gel isolation segment 101, thereby accurately determining the changes in the state of the gel isolation segment 101.

[0054] Step 302: The monitoring device issues an alarm signal based on the real-time temperature data exceeding the temperature safety threshold and / or the real-time pressure data exceeding the pressure safety threshold.

[0055] The monitoring equipment compares real-time temperature data with temperature safety thresholds, real-time pressure data, and pressure safety thresholds. If the real-time temperature data exceeds the temperature safety threshold and / or the real-time pressure data exceeds the pressure safety threshold, the equipment automatically outputs an alarm signal. Similarly, the monitoring equipment can also output an alarm signal when it detects a change in the gel isolation section 101.

[0056] The above embodiments monitor the real-time temperature and pressure data of the goaf 102 and set corresponding temperature and pressure safety thresholds. The monitoring equipment can automatically compare the collected real-time temperature and pressure data with the preset thresholds. When any data exceeds the limit, an alarm signal is immediately issued, enabling staff to grasp dangerous signs such as abnormal temperature rise or stress change in the goaf 102 in a timely manner and take grouting or reinforcement measures. Simultaneously, by importing the data into Excel and numerical analysis software and constructing visualization graphs, the monitoring equipment can compare and analyze the state of the goaf 102 with historical data, thereby improving the accuracy of identifying the trend of goaf 102 status changes and the reliability of early warning. This solves the subjectivity and lag of manual inspection and provides a data-driven, automated, and visualized intelligent control method for goaf 102 safety monitoring, effectively reducing the probability of fires caused by air leakage due to goaf 102 collapse.

[0057] In some embodiments, step 2033 includes: Step 2033a: After receiving the alarm signal, the staff prepares a sol, uses an injection device to draw in the sol and injects it into the goaf 102 through the detection hole 107.

[0058] Upon receiving the alarm signal, staff immediately began preparing the sol, which was then injected into the goaf 102 through the probe hole 107 using a dispensing device. When preparing the sol, the required dispensing volume needs to be determined first. For example, the dispensing volume is determined as follows: first, the dispensing volume required for each gel isolation segment 101 is determined based on the volume of the constructed gel isolation segment 101. Assume the required dispensing volume for each gel isolation segment 101 is Q. i Based on the length of the goaf 102, the number of gel isolation sections 101 to be constructed is determined to be N. Therefore, the total amount of gel injection required to construct the gel isolation sections 101 is Q. a =Q i ×N, while the amount of adhesive required to seal the collapsed cavity or reinforce the gel isolation section 101 can be determined as 20% of the total adhesive amount.

[0059] During the grouting process in goaf 102, workers need to stay away from the connection point between the grouting equipment and goaf 102, which is the grouting hole 105 or the detection hole 107. Preferably, workers should maintain a distance of at least 5 meters from the grouting hole 105 or the detection hole 107. If grout leakage occurs in the grouting hole 105 or the detection hole 107, grouting at that location must be stopped. Furthermore, workers can also open a spare hole near the grouting hole 105 or the detection hole 107. If grouting in the grouting hole 105 or the detection hole 107 is not smooth or there is serious leakage, grouting can be performed through the spare hole. However, before using the spare hole, the pipes of the spare hole should be flushed with clean water to ensure that the pipes are unobstructed.

[0060] Step 2033b: Based on the vibration of the dispensing equipment and / or the leakage of molten adhesive from the detection hole 107, the operator shuts down the dispensing equipment.

[0061] If the dispensing equipment vibrates and / or molten adhesive flows out near the probe hole 107, it is confirmed that the dispensing volume is up to standard, and the staff can turn off the dispensing equipment.

[0062] Step 2033c: After the staff determines the solidification effect of the sol injected into the goaf 102, and confirms that the collapse cavity formed by the collapse has been sealed and / or the gel isolation section 101 has returned to a stable state, the pipe between the sol injection equipment and the probe hole 107 is removed.

[0063] The pipe between the dispensing equipment and the probe hole 107 can be a high-pressure hose. High-pressure hoses need to be connected using U-shaped pins to prevent leakage, spillage, dripping, or other problems at the connection point. The dispensing equipment includes a mixer with an observation valve. After dispensing is complete, a designated operator can open the mixer's observation valve to check the solidification effect of the solvent.

[0064] In the above embodiments, by pre-calculating the amount of adhesive required for reinforcing the collapsed cavity based on the total volume of the gel isolation section 101, the preparation and injection process of the sol becomes more targeted, avoiding material waste or insufficient sealing. During the injection process, workers are required to maintain a safe distance of at least 5 meters, and spare holes are pre-set near the injection hole 105 or the detection hole 107. In case of blockage or severe leakage, the injection channel can be switched. The spare holes are flushed with clean water before use to ensure unobstructed flow, effectively improving the continuity and safety of the injection operation. The vibration of the injection equipment or the return of slurry at the orifice is used as a criterion for judging whether the injection volume is up to standard. After the injection is completed, the solidification effect of the sol is visually confirmed through the valve of the mixer observation port. The pipeline is only removed after the collapsed cavity is effectively sealed or the gel isolation section 101 has returned to stability. The above embodiments not only avoid insufficient or excessive redundancy of the prepared sol, but also provide a method for judging the solidification of the sol, reducing the operational risks and failure probability during the grouting process, and providing reliable technical support for the accurate, safe, and efficient sealing of the goaf 102.

[0065] Furthermore, the underground coal mine 10 also includes a single-ended roadway 106. During the mining of the lower coal seam, when the goaf 102 collapses along with the longwall face 104, the goaf 102 and the longwall face 104 will collapse vertically to the new goaf 102 formed by the longwall face 104. In this case, workers can drill holes in the single-ended roadway 106, which is near the stop line and on the same horizontal line as the new goaf 102 formed by the longwall face 104, to detect whether there are cavities in the suspected collapse area. If there are cavities, they are filled by injecting colloid along the drill holes. In addition, as the longwall face 104 advances a certain distance, two temporary construction isolation walls can be constructed at certain intervals in the return airway 103. Workers will conduct coal mining operations between these two temporary isolation walls. The temporary isolation walls can be constructed of double-layered coal slurry bags, and their surfaces will be sprayed with a solvent-based coating to prevent the sudden influx of flammable and explosive gases into the working area. The monitoring components may also include gas sensing elements, such as CO and CH4 gas sensors. These gas sensing elements can be installed on top of the temporary isolation walls to monitor the concentration of flammable and explosive gases between the two walls. Furthermore, a windbreak curtain can be hung on the side of the temporary isolation wall closest to the workers' work area to provide secondary protection against the sudden influx of flammable and explosive gases into the roadway.

[0066] In some embodiments, the sol includes a coagulant, which is made from dry material and water in a preset second ratio, wherein the second ratio k2 satisfies: 1:5 ≤ k2 ≤ 1:3.

[0067] Preferably, the second ratio can be determined to be 1:4, and the dry material can be Puris gel dry material. For example, in preparing the sol, the dry material and water are first thoroughly mixed in a mixing tank at a ratio of 1:4 and stirred evenly to ensure that the base material is fully dissolved in the water. Then, water glass solution and baking soda solution are simultaneously pumped to the mixer along with a pre-prepared coagulant. After thorough mixing, the sol is formed and injected into the goaf through the injection pipeline. During the injection process, a designated person periodically opens the observation valve of the mixer to check the gel formation effect, confirming that the gel solidifies normally and has a uniform color, thus ensuring the quality of the injection.

[0068] It should be noted that, in this document, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitations, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes that element. Furthermore, it should be noted that the scope of the methods and apparatuses in the embodiments of this application is not limited to performing functions in the order shown or discussed, but may also include performing functions substantially simultaneously or in the reverse order, depending on the functions involved. For example, the described methods may be performed in a different order than described, and various steps may be added, omitted, or combined. Additionally, features described with reference to certain examples may be combined in other examples.

[0069] The embodiments of this application have been described above with reference to the accompanying drawings. However, this application is not limited to the specific embodiments described above. The specific embodiments described above are merely illustrative and not restrictive. Those skilled in the art can make many other forms under the guidance of this application without departing from the spirit and scope of the claims, and all of these forms are within the protection scope of this application.

Claims

1. A method for sealing coal seam goaf, characterized in that, Used in underground coal seam mining operations, the underground coal mine includes a working area, a goaf, a lower coal seam, a longwall face, intake and return airway, and a return air roadway. The lower coal seam is located below the goaf. The sealing method includes: Before the lower coal seam is mined, sol is injected into the goaf through the return air roadway in the working area to construct multiple gel isolation sections. During the mining of the lower coal seam, when a goaf occurs perpendicular to the strike of the lower coal seam, a detection hole is opened in the horizontal direction through the intake and return airway. Natural cavities are identified through the detection holes, and the state of the gel isolation section and goaf is monitored through the natural cavities. When a collapse and / or a collapse cavity is detected in the goaf, the sol is injected into the goaf.

2. The method for sealing the goaf of the lower coal seam according to claim 1, characterized in that, The process of injecting sol into the goaf through the return air roadway to construct multiple gel isolation sections includes: Multiple injection holes are opened in the goaf through the return air roadway, and a drill pipe is installed in the injection hole. The drill pipe is fixed around the perimeter with a cementitious material. The sol is prepared according to a preset first ratio, and injected into the goaf area through the plurality of injection holes using a sol injection device. The sol is shut down when the sol injection device vibrates and / or the sol flows out of the injection holes.

3. The method for sealing coal seam goaf according to claim 2, characterized in that, The cementing material includes: cement, lime or gypsum.

4. The method for sealing coal seam goaf according to claim 2, characterized in that, The preset first ratio k1 satisfies: 1:7≤k1≤1:

5.

5. The method for sealing coal seam goaf according to claim 2, characterized in that, The height h of the injection hole satisfies: 1cm≤h≤2cm; The diameter r of the injection hole satisfies: 2cm≤r≤4cm.

6. The method for sealing coal seam goaf according to any one of claims 1 to 5, characterized in that, The process involves identifying natural cavities through the detection holes and monitoring the state of the gel isolation section and the goaf through these cavities. When a collapse and / or a collapse cavity is detected in the goaf, the sol is injected into the goaf, including: A detection element is installed in the detection hole, and a monitoring device is installed in the work area. The detection element is communicatively connected to the monitoring device, and the natural cavity is detected using the detection element and the monitoring device. After determining the existence of the natural cavity based on the detection element and the monitoring equipment, a monitoring component is set in the natural cavity to obtain the status data of the gel isolation section and the goaf, and a communication connection is established between the monitoring component and the monitoring equipment. The monitoring device receives the status data and issues an alarm signal when the status data exceeds the corresponding preset safety threshold, and injects the sol into the goaf area based on the alarm signal.

7. The method for sealing coal seam goaf according to claim 6, characterized in that, The monitoring component includes a temperature sensing element, a pressure sensing element, and a detection element, all of which are communicatively connected to the monitoring equipment.

8. The method for sealing coal seam goaf according to claim 6, characterized in that, The status data includes real-time temperature data and real-time pressure data, and the preset safety thresholds include temperature safety thresholds and pressure safety thresholds. The monitoring device is capable of: Acquire the real-time temperature data and the real-time pressure data, and compare the real-time temperature data with the temperature safety threshold and the real-time pressure data with the pressure safety threshold, respectively. The alarm signal is issued based on the real-time temperature data exceeding the temperature safety threshold and / or the real-time pressure data exceeding the pressure safety threshold.

9. The method for sealing coal seam goaf according to claim 6, characterized in that, The injection of the sol into the goaf based on the alarm signal includes: Based on receiving the alarm signal, the sol is prepared, and the sol is drawn in by the injection equipment and injected into the goaf through the detection hole; If the dispensing equipment vibrates and / or the sol flows out of the detection hole, shut down the dispensing equipment. After determining the solidification effect of the sol injected into the goaf, and confirming that the collapse cavity formed by the collapse has been sealed and / or the gel isolation section has returned to a stable state, the pipeline between the sol injection equipment and the detection hole is removed.

10. The method for sealing coal seam goaf according to any one of claims 1 to 9, characterized in that, The sol includes a coagulant, which is made from dry material and water in a preset second ratio, wherein the second ratio k2 satisfies: 1:5≤k2≤1:3.

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