Grouting can not only reduce the oxygen supply in the goaf, but also reduce the temperature in the goaf for fire prevention. It can also be used for fire prevention in a wide range of fire zones. 1) Soil to soil ratio The water-soil ratio is between 2:1 and 4:1, depending on the location of the grouting; the amount of grouting in the goaf can be as good as covering 2 cm of loess in the goaf. 2) Grouting method It adopts two methods: mining with irrigation and post-harvest grouting. With mining and irrigation: at the same time as the working surface advances, the goaf is grouted. The grouting pipeline is laid on a roadway with a higher elevation in the two sides of the working face. The slurry flows by the self-weight to the goaf in the lower part. The grouting pipeline should be buried in the goaf for about 15-20m, and then grouting is started to prevent the slurry from smearing. The slurry is alternately filled daily. Post-harvest grouting: Grouting after the closed face of the working face is closed, and the grout is filled on the closed wall of the stop-line line until it is filled. 3) Calculation of soil volume for grouting With the working face, the amount of soil required for daily grouting is calculated by the following formula: Qt=K•m•l•H•C Wherein: Qt- Japanese desired filling quantity of soil, m3 / d; high-level coal mining m-, m; - date of advance of the face, m / d; H- grout region inclined length, m; C- Coal Mining Rate, %; K - grouting coefficient, according to the actual situation of the mining area, generally take 0.014--0.03; 4) Selection of grouting process Commonly used grouting categories include: infusion of loess slurry, "infusion of loess slurry + inhibitor", "infusion of high concentration loess + thickened colloidal slurry", composite colloidal mud and so on. Under normal circumstances, the “high-concentration loess + inhibitor†grouting process is followed by the injection; when there is a fire sign in the goaf of the working face, the “composite colloidal mud†grouting process is adopted, and the composite colloidal mud is composed of loess and water. , suspension agent, gelling agent composition. The suspending agent is added in proportion to the loess slurry in the ground grouting tank, and after being uniformly stirred, a thickened colloid is formed and transported to the well through the grouting pipeline system. 2 inhibitors fire protection technology Inhibitors are compounds there are inorganic salts such as calcium chloride (CaCl2.6H2O), magnesium chloride (MgCl2.6 H2O), ammonium chloride (NH4Cl) solution is sprayed on the coal and the like, having a blocking oxide, To prevent the effect of spontaneous combustion, it is called a resisting agent. It can effectively prevent the natural fire of coal seam by spraying and injecting inhibitor in coal mine. 1) Selection of inhibitors and their technical parameters. According to the actual situation of the mine, the use of MgCl2 as a retarding agent can achieve better results and is convenient to obtain. The concentration of the inhibitor solution is preferably controlled between 18 and 20%. 2) Location and time of spraying. Spraying location: two gangs in the lower two lanes on the working face, the floating coal at the rear of the two ends of the brackets, and the gap between the brackets in the rear goaf. Spraying time: After each shift of the working surface. 3 Wall fire prevention technology The building fire wall is a wall made of sand or loess bagged on the back side of the goaf in the two working faces of the working face. Its function is to reduce the air leakage in the goaf of the two lanes, reduce the oxidation zone and the air leakage zone, and increase the length of the asphyxiation zone. The ultimate goal is to minimize the oxidation zone length of the floating coal in the goaf and reduce the natural fire accident of the floating coal in the goaf. . How long it takes to build a fire barrier against the work surface is the key to the functioning of the firewall. The best position of the fire barrier wall should be 10 meters. Because the working surface advances faster, the speed of one day is nearly 9 meters. Therefore, the construction of a fire wall has a large workload and the transportation of wall materials is difficult. It is more practical to have a fire barrier wall in Mijian, and the carbon monoxide and gas concentrations in the goaf and return air angle are not exceeded. The thickness of the building fire barrier is controlled between 1.5 and 3 meters. The two gangs are closely linked to the goaf and the coal gang, which really acts as a plugging leak. 4 working surface with anti-fire extinguishing technology During the advancement of the working face, a meteorite belt with a width of 5 to 8 meters is placed along the surface for 30 meters. The meteorite belt plays the following roles: 1) reducing the residual coal in the goaf; 2) acting as a separation wall in the goaf. Reduce the leakage of air in the goaf; 3) shorten the length of the oxidation zone in the goaf and speed up the entry into the suffocation zone; 4) reduce the space of the goaf and effectively reduce the amount of harmful gas from the return air. 5 stop mining line drilling pre-grouting technology Grouting in the goaf of the working face is the most important measure for the safe evacuation of the working face. The implementation of the fire prevention and drilling of the goaf in the working face is the key to grouting in the goaf. When the working surface is close to the stop line 50 meters, five holes will be constructed along the working surface track along the channel at 1.2 meters above the floor. The drilling holes are arranged in a fan shape, and the range of 5 to 10 meters behind each drilling control frame is controlled to be about 3 to 5 meters from the top of the frame. According to the site to develop strict and feasible drilling parameters, immediately after the completion of the drilling, the coal mine plugging agent shall be injected into the goaf through drilling to prevent the gob from spontaneous combustion during the retracement period. 6 human-machine combined with natural fire prediction technology Using the KSS-200 beam tube monitoring system and the KJ95 safety monitoring and monitoring system, three sensors are arranged in the return flow of the working face, namely methane sensor, temperature sensor and carbon monoxide sensor, and the gas, temperature, and Carbon monoxide was continuously monitored for 24 hours. At the return angle of the working face, the beam tube sampler is installed, and a beam tube sampler is buried within 30 meters from the goaf of the working face, and is laid along with the advancement of the working surface. A beam tube sampler is laid on the return angle of the working face to sample and analyze the return air angle of the working face, and a sampling analysis is carried out once a day to understand the gas outflow of the working face and the return air angle. The results of the analysis are taken in a timely manner for effective measures. The gas inspectors inspected the gas flow in the lower corner of the coal mining face, the wind flow near the cutting line, the wind flow in the coal mining face, the gas in the return flow of the coal mining face, the carbon dioxide, carbon monoxide, and the temperature at least twice. The mine dispatching room, the general defense department, and the mine pass defense department immediately sent people to the downhole for analysis and processing. 7 pressure equalizing ventilation and fire prevention technology The safe, reliable, stable and reasonable mine ventilation system is the key to mine fire prevention work. The key to affecting the stability of the mine ventilation system is the timely and reasonable setting of ventilation facilities. After the end of the mining face, adjust the ventilation system in time, build ventilation facilities, form a pressure equalization ventilation, reduce air leakage in the goaf, and prevent spontaneous combustion of the residual coal in the goaf. According to the actual situation of the mine, Liangbaosi Coal Mine has increased investment, introduced high-tech technology, replaced all dampers with pressureless polymer dampers, and set up automatic control devices. All dampers in the well are visualized, automated, and locked. Ensure that the mine ventilation system is safe, reliable, stable and reasonable. 8 nitrogen injection fire prevention technology Nitrogen is a chemically stable gas that is difficult to chemically react with other substances under normal temperature and pressure conditions and is a good inert gas. As the nitrogen content in the air increases, the oxygen content necessarily decreases. Therefore, when the oxygen content is reduced to 5 to 10%, the oxidation self-ignition of coal can be suppressed, and when the oxygen content falls below 3%, the combustible and re-ignition of combustibles such as coal can be completely suppressed. Based on the above fire prevention mechanism, the nitrogen generator system was purchased, and nitrogen gas was injected into the goaf of the fully mechanized caving face, and it was infiltrated into the caving zone and the fracture zone of the goaf to form a nitrogen inerting zone, which can suppress the spontaneous combustion of the goaf. the goal of.
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1 preventive grouting fire prevention technology