Biological inhibition material, grouting system and application of biological inhibition material in prevention and control of spontaneous combustion of coal in goaf

Abstract

The invention relates to the technical field of coal mine fire prevention and control, and provides a biological inhibition material, a grouting system and application of the biological inhibition material to prevention and control of spontaneous combustion of goaf coal. The biological inhibition material provided by the invention comprises a component A and a component B, wherein the component A comprises solid waste, soluble calcium salt and urea; and the component B comprises urease. The biological inhibition material provided by the invention can reduce pores of coal, form a compact isolation layer on the surface of a coal body, reduce the reaction area of the coal and oxygen, and effectively inhibit the spontaneous combustion process of the coal; according to the biological inhibition material, a large amount of solid waste is adopted, and waste treatment can be achieved. The invention further provides a grouting system, the grouting system can prepare the urease solution and the slurry at the same time, operation is easy, working efficiency is high, and efficient grouting can be achieved; furthermore, by additionally arranging a control system, intelligent preparation of the biological inhibition material and intelligent control over the perfusion amount can be achieved, manual assistance is not needed, and a large amount of manpower and material resources are saved.

Description

Technical Field

[0001] The present invention relates to the technical field of coal mine fire prevention and control, and particularly relates to a biological inhibitor material, a grouting system, and an application thereof in preventing spontaneous combustion of coal in a gob area. Background Art

[0002] Spontaneous combustion of coal is a major risk factor threatening the safe production of coal mines. The mine fires caused by spontaneous combustion of coal will not only cause huge economic losses to coal mines, but also pose a serious threat to the life safety of underground workers. The gob area underground is a semi-closed space formed by the accumulation of broken coal and rock masses, with a large amount of left coal and many air leakage channels. The broken and accumulated coal masses are prone to heat accumulation, which is the main area where spontaneous combustion occurs.

[0003] At present, using inhibitor materials is one of the main measures to prevent spontaneous combustion of coal. According to different inhibition methods, inhibitor materials can be divided into physical inhibitor materials, chemical inhibitor materials, and physical-chemical composite inhibitor materials. Among them, the commonly used physical inhibitor materials are mainly halogen salts, which achieve the inhibition effect by absorbing moisture to form a water film to cover the coal seam surface and isolate oxygen; the commonly used chemical inhibitor materials are mainly antioxidants, which achieve the inhibition effect by scavenging active free radicals in coal. However, the above-mentioned inhibitor materials all have the problem of low inhibition efficiency.

[0004] Moreover, the current inhibitor materials are usually injected into the coal cracks in the gob area through a grouting system, but the current grouting system has low working efficiency and cannot achieve efficient perfusion operations. Summary of the Invention

[0005] In view of this, the present invention provides a biological inhibitor material, a grouting system, and an application thereof in preventing spontaneous combustion of coal in a gob area. The biological inhibitor material provided by the present invention has a high inhibition rate and can effectively prevent spontaneous combustion of the left coal in the gob area; the grouting system provided by the present invention realizes high integration, is easy to operate, has high working efficiency, and can achieve efficient perfusion operations.

[0006] In order to achieve the above-mentioned invention purposes, the present invention provides the following technical solutions:

[0007] A biological inhibitor material, comprising component A and component B;

[0008] The component A consists of the following components in parts by mass: 500 - 2500 parts of solid waste, 40 - 360 parts of soluble calcium salt, and 20 - 125 parts of urea; the solid waste includes one or more of fly ash, carbide slag, red mud, blast furnace slag, mine sludge, and steel slag;

[0009] The component B includes urease.

[0010] Preferably, the solid waste is fly ash and carbide slag, and the mass ratio of fly ash to carbide slag is 1:0.5 - 1.3; the soluble calcium salt includes one or more of calcium chloride, calcium formate, calcium nitrate, and calcium acetate; the urease is soybean urease.

[0011] The present invention also provides an application of the biological inhibitor material described in the above solution in preventing and controlling coal spontaneous combustion in goafs.

[0012] Preferably, the method of the application includes:

[0013] Mix the solid waste, soluble calcium salt, urea, and water to obtain a slurry;

[0014] Inject the slurry and urease solution into the area in the goaf that needs to be treated.

[0015] Preferably, the preparation method of the urease solution includes Method 1 or Method 2. Method 1 includes: crush soybeans and mix them with water, and then filter to obtain the urease solution; the mass ratio of soybeans to water in Method 1 is 0.9 - 1.2:10;

[0016] Method 2 includes: crush soybeans and mix them with an ethanol aqueous solution for oscillation, then refrigerate and centrifuge in sequence to obtain a urease extract, and mix the urease extract with water to obtain the urease solution; the dosage ratio of soybeans to the ethanol aqueous solution in Method 2 is 1g:8 - 15mL, and the volume ratio of the urease extract to water is preferably 1:35 - 68;

[0017] The content of the solid waste in the slurry is 500 - 2500g / L, the concentration of the soluble calcium salt is 0.4 - 2mol / L, and the concentration of urea is 0.4 - 2mol / L;

[0018] The volume ratio of the slurry to the urease solution is 2.7 - 3.2:1.

[0019] The present invention also provides a grouting system, including a urease solution production system, a slurry production system, and a three-way grouting pipe:

[0020] The urease solution production system includes:

[0021] A soybean storage bin; a soybean outlet is provided at the bottom of the soybean storage bin;

[0022] A urease maker; the urease maker is communicated with a first water injection pipe;

[0023] A conveying device; the conveying device is used to transport the soybeans in the soybean storage bin to the urease maker;

[0024] The slurry production system includes:

[0025] Cementing liquid production and storage bin; the cementing liquid production and storage bin is communicated with the second water injection pipe;

[0026] Slurry maker; the slurry maker includes a mixing tank body, and a cementing liquid inlet, a solid waste inlet and a slurry outlet are arranged on the mixing tank body; the cementing liquid inlet is communicated with the outlet of the cementing liquid production and storage bin;

[0027] Solid waste storage bin; the solid waste storage bin is communicated with the solid waste inlet of the slurry maker;

[0028] The outlet of the urease maker and the outlet of the slurry maker are respectively communicated with the three-way grouting pipe.

[0029] Preferably, a first flow control valve is arranged on the pipeline of the first water injection pipe;

[0030] A first power pump and a second flow control valve are arranged on the pipeline where the outlet of the urease maker is communicated with the three-way grouting pipe;

[0031] A second power pump and a third flow control valve are arranged on the pipeline of the second water injection pipe;

[0032] A third power pump and a fourth flow control valve are arranged on the pipeline where the solid waste storage bin is communicated with the slurry maker;

[0033] A fourth power pump and a fifth flow control valve are arranged on the pipeline where the outlet of the slurry maker is communicated with the three-way grouting pipe.

[0034] Preferably, a feeding port is arranged at the top of the urease maker, and the end of the conveying device is communicated with the feeding port; a crusher and a filter screen are arranged inside the urease maker, the filter screen is arranged vertically, and the inside of the urease maker is divided into a crude urease solution production area and a urease solution storage area; a urease solution outlet is arranged on the side wall of the urease solution storage area; a baffle is arranged on the bottom plate of the urease solution production area, and a soybean residue outlet is arranged below the baffle;

[0035] The bottom of the tank body of the soybean storage bin is conical, and the soybean outlet is located above the front end of the conveying device.

[0036] Preferably, quality control devices are arranged in the soybean storage bin, the cementing liquid production and storage bin and the solid waste storage bin;

[0037] The grouting system further includes a cloud signal receiver and a control system; the control system is used to input control information to control the operation of the grouting system; the cloud signal receiver is used to receive the signals of the coal spontaneous combustion monitoring and early warning system in the goaf and transmit them to the control system, so that the grouting system and the coal spontaneous combustion monitoring and early warning system in the goaf form a linkage; when the coal spontaneous combustion monitoring and early warning system monitors abnormal temperature and index gas concentration in the goaf, the control system issues a start grouting signal, and when the coal spontaneous combustion monitoring and early warning system monitors that the temperature and index gas concentration in the goaf return to normal, the control system issues a stop grouting signal.

[0038] The present invention also provides a method for grouting using the grouting system described in the above solution, including the following steps:

[0039] Using soybeans and water as raw materials, prepare urease solution through the urease solution production system;

[0040] Using solid waste, soluble calcium salt, urea and water as raw materials, prepare slurry through the slurry production system;

[0041] Inject the urease solution and the slurry into the three-way grouting pipe, and the three-way grouting pipe is connected to the goaf to inject the urease solution and the slurry into the goaf.

[0042] The present invention provides a biological inhibitor material, which comprises component A and component B; the component A consists of the following components in parts by mass: 500 - 2500 parts of solid waste, 40 - 360 parts of soluble calcium salt, and 20 - 125 parts of urea; the solid waste includes one or more of fly ash, carbide slag, red mud, blast furnace slag, mine sludge, and steel slag; the component B includes urease. The inhibition principle of the biological inhibitor material provided by the present invention is as follows: urease hydrolyzes urea to produce carbonate ions, and the carbonate ions combine with calcium ions (provided by the solid waste and calcium chloride) to undergo mineralization to produce calcium carbonate. The calcium carbonate adheres to the solid waste particles and the coal surface. Under the cementing action of calcium carbonate, the solid waste particles and calcium carbonate form a cementing body on the coal surface to wrap the coal body, forming a dense isolation layer to prevent the coal from contacting with oxygen; moreover, the calcium carbonate produced by mineralization has a very small particle size and can fill the pores in the coal seam, thereby preventing oxygen from entering and greatly reducing the oxidation reaction of the coal; in addition, the solid waste adopted in the present invention has a certain alkalinity and can provide an alkaline environment. The calcium ions that have not formed calcium carbonate exist in the form of calcium hydroxide, and the calcium hydroxide can also fill the cracks in the coal, making the structure of the loose coal body denser; furthermore, the biological inhibitor material of the present invention can also change the structure of the functional groups in the coal, reduce the content of aliphatic hydrocarbons and aromatic hydrocarbons that promote combustion, and increase the content of hydroxyl groups that can capture free radicals. In summary, the biological inhibitor material of the present invention can reduce the pores of the coal, form a dense isolation layer on the coal body surface, reduce the reaction area between the coal and oxygen, and effectively inhibit the coal spontaneous combustion process. The results of the examples show that the inhibition rate of the biological inhibitor material of the present invention can reach 73.08%. In addition, the biological inhibitor material of the present invention uses a large amount of solid waste and can realize the treatment of waste.

[0043] The present invention also provides a grouting system. The grouting system provided by the present invention can simultaneously prepare urease solution and slurry, is easy to operate, has high working efficiency, and can achieve high-efficiency perfusion; further, by adding a control system, the present invention can realize the intelligent preparation of the biological inhibitor material and the intelligent control of the perfusion amount, without manual assistance, saving a large amount of manpower and material resources. In summary, the grouting system of the present invention realizes highly integrated, is easy to operate, can intelligently control the dosage and injection of raw materials, and solves the technical problems of the integrated preparation and injection of mine biological inhibitor materials. Description of the Drawings

[0044] Figure 1 is a schematic structural diagram of the grouting system provided by the present invention;

[0045] Figure 2 is a schematic structural diagram of a soybean storage bin;

[0046] Figure 3 is a schematic structural diagram of a urease maker;

[0047] Figure 4It is a structural schematic diagram of a slurry maker;

[0048] Figures 1 to 4 Among them: 1 - soybean storage bin, 1-1 - soybean outlet, 1-2 - tank body, 1-3 - pillar of soybean storage bin, 2 - conveying device, 3-1 - first flow control valve, 3-2 - second flow control valve, 3-3 - third flow control valve, 3-4 - fourth flow control valve, 3-5 - fifth flow control valve, 4 - urease maker, 4-1 - feeding port, 4-2 - crusher, 4-3 - baffle, 4-4 - soybean residue outlet, 4-5 - water inlet of urease maker, 4-6 - filter screen, 4-7 - column of urease maker, 4-8 - urease solution outlet, 5-1 - first power pump, 5-2 - second power pump, 5-3 - third power pump, 5-4 - fourth power pump, 6 - first water injection pipe, 7 - cementitious liquid production and storage bin, 8 - solid waste storage bin, 9 - slurry maker, 9-1 - cementitious liquid inlet, 9-2 - solid waste inlet, 9-3 - slurry outlet, 9-4 - mixing tank body, 10 - three-way grouting port, 11 - cloud signal receiver, 12 - control system, 13 - second water injection pipe;

[0049] Figure 5 It is the XRD pattern of each test sample in Example 1;

[0050] Figure 6 It is the infrared spectrum curve (a) and functional group proportion (b) of each test sample in Example 1;

[0051] Figure 7 It is the variation diagram of CO gas content with temperature of different test samples in Example 1;

[0052] Figure 8 It is the test results of the crossover temperature of different test samples in Example 1;

[0053] Figure 9 It is the HRR curve (a) and THR curve (b) of different test samples in Example 1;

[0054] Figure 10 It is the test results of the CO production amount of different test samples in Example 1;

[0055] Figure 11 It is the test results of the smoke production rate (a) and total smoke production amount (b) of different test samples in Example 1;

[0056] Figure 12 It is the simulation test platform for the fire extinguishing test in Example 1;

[0057] Figure 13Fire extinguishing test results in Example 1, where: (a) is the FET-WA sample; (b) is the FET-FA-CES-CC-SUS sample; (c) is the FET-CS-CES-CC-SUS sample; (d) is the FET-FA-CS-CES-CC-SUS sample; (e) is the FET-FA-CS-CES-CF-SUS sample; (f) is the FET-CES-CC-SUS sample; (g) is the FET-CES-CC-SUS sample. Detailed implementation mode

[0058] The present invention provides a mine biological inhibitor material based on soybean dregs, comprising component A and component B;

[0059] The component A consists of the following components in parts by mass: 500-2500 parts of solid waste, 40-360 parts of soluble calcium salt, and 20-125 parts of urea; the solid waste includes one or more of fly ash, carbide slag, red mud, blast furnace slag, mine sludge, and steel slag;

[0060] The component B includes urease.

[0061] In parts by mass, the component A includes 500-2500 parts of solid waste, specifically 510 parts, 550 parts, 600 parts, 1000 parts, 1050 parts, 1500 parts, 2000 parts, or 2500 parts; the solid waste includes one or more of fly ash, carbide slag, red mud, blast furnace slag, mine sludge, and steel slag; the solid waste is preferably solid waste particles, and the particle size of the solid waste particles is preferably 0.3-320 μm, specifically 0.5 μm, 1 μm, 5 μm, 10 μm, 50 μm, 100 μm, 200 μm, or 300 μm; in a specific embodiment of the present invention, the solid waste is preferably fly ash (FA) and carbide slag (CS); the mass ratio of fly ash to carbide slag is preferably 1:0.5-1.3, specifically 1:0.6, 1:0.8, or 1:1. In the present invention, CS can provide an alkaline environment, and in the alkaline environment, the vitreous structure in FA will be destroyed, and the internal Si-O and Al-O ions will be exposed and gradually released.

[0062] Based on the parts by mass of the solid waste, the component A includes 40 - 360 parts of soluble calcium salt, specifically it can be 40 parts, 60 parts, 90 parts, 95 parts, 100 parts, 110 parts, 120 parts, 125 parts, 200 parts, 300 parts or 350 parts; the soluble calcium salt preferably includes one or more of calcium chloride, calcium formate, calcium nitrate and calcium acetate, more preferably one or two of calcium chloride and calcium formate, and further preferably calcium chloride; specifically, when the soluble calcium salt is calcium chloride, the mass parts of the calcium chloride are preferably 44 - 225 parts, when the soluble calcium salt is calcium formate, the mass parts of the calcium formate are preferably 52 - 261 parts, when the soluble calcium salt is calcium nitrate, the mass parts of the calcium nitrate are preferably 65 - 328 parts, and when the soluble calcium salt is calcium acetate, the mass parts of the calcium acetate are preferably 70 - 353 parts.

[0063] Based on the parts by mass of the solid waste, the component A includes 20 - 125 parts of urea, preferably 24 - 120 parts, and specifically it can be 25 parts, 50 parts, 55 parts, 60 parts, 65 parts, 70 parts, 80 parts, 100 parts or 110 parts.

[0064] In the present invention, the component B includes urease; the urease is preferably soybean urease; the preparation raw materials of the component B preferably include soybean and water; the soybean can specifically be soybean powder; in the specific embodiments of the present invention, the urease is specifically used in the form of urease solution, and the concentration of urease in the urease solution is preferably 8 - 15 g / mL, and the urease activity is 15 - 26 mmol / L / min; the preparation method of the urease solution will be described in detail later.

[0065] The present invention also provides the application of the above-mentioned mine biological inhibitor material based on soybean residue in preventing and controlling coal spontaneous combustion in goaf.

[0066] In the present invention, the method of the application preferably includes: mixing the solid waste, soluble calcium salt, urea and water to obtain a slurry; injecting the slurry and the urease solution into the goaf. In the present invention, the content of the solid waste in the slurry is preferably 500 - 2500 g / L, specifically it can be 510 g / L, 550 g / L, 600 g / L, 1000 g / L, 1050 g / L, 1500 g / L or 2000 g / L; the concentration of the soluble calcium salt in the slurry is preferably 0.4 - 2 mol / L, specifically it can be 0.5 mol / L, 1 mol / L or 1.5 mol / L; the concentration of the urea in the slurry is preferably 0.4 - 2 mol / L, specifically it can be 0.5 mol / L, 1 mol / L or 1.5 mol / L.

[0067] In the present invention, the preparation method of the urease solution preferably includes Method 1 and Method 2, which will be described respectively below.

[0068] In the present invention, the first method preferably includes: crushing soybeans and mixing them with water, and then filtering to obtain a urease solution; the mass ratio of soybeans to water in the first method is preferably 0.9 - 1.2:10, specifically it can be 1:1 or 1.1:1; the mixing time is preferably 20 - 35 min.

[0069] In the present invention, the second method preferably includes: crushing soybeans and mixing them with an aqueous ethanol solution for oscillation, then successively performing refrigeration and centrifugation to obtain a urease extract, and mixing the urease extract with water to obtain a urease solution; the dosage ratio of soybeans to the aqueous ethanol solution in the second method is preferably 1 g:10 mL; the volume fraction of the aqueous ethanol solution is preferably 25 - 35%, more preferably 30%; the oscillation frequency is preferably 180 - 300 rpm, more preferably 200 rpm, the oscillation time is preferably 2 - 4 h, more preferably 3 h, the refrigeration temperature is preferably 1 - 6 °C, the time is preferably 10 - 16 h, more preferably 12 h; in the present invention, refrigeration enables more urease to enter the liquid phase; the volume ratio of the urease extract to water is preferably 1:35 - 68.

[0070] In the present invention, the first method is simple to operate and easy to carry out; the second method has a high urease extraction rate, but the operation is relatively complex. In the specific embodiments of the present invention, when grouting is carried out using the grouting system of the present invention, the preparation method of the urease solution is the first method.

[0071] The present invention also provides a grouting system, including a urease solution production system, a slurry production system, and a three-way grouting pipe. The specific structure of the pressing system is as Figure 1 shown. The following will be described in detail in combination with Figure 1 the grouting system.

[0072] In the present invention, the urease solution production system includes a soybean storage bin 1, and the structural schematic diagram of the soybean storage bin is as Figure 2 shown; a soybean outlet 1 - 1 is provided at the bottom of the soybean storage bin 1, and the soybean outlet 1 - 1 is an intelligent outlet, and the opening and closing of the soybean outlet are controlled by a control system; the bottom of the tank body 1 - 2 of the soybean storage bin 1 is conical, and the soybean outlet 1 - 1 is located above the front end of the conveyor device 2; support columns 1 - 3 are further provided around the bottom of the tank body 1 - 2 of the soybean storage bin for supporting the tank body 1 - 2.

[0073] In the present invention, the urease solution production system includes a urease producer 4, and the structural schematic diagram of the urease producer 4 is as Figure 3As shown in the figure; the urease maker 4 is communicated with the first water injection pipe 6; a feeding port 4-1 is arranged at the top of the urease maker 4, and the end of the conveying device 2 is communicated with the feeding port 4-1; a crusher 4-2 and a filter screen 4-6 are arranged inside the urease maker 4, and the crusher 4-2 is used for crushing soybeans to produce soybean powder; the filter screen 4-6 is preferably arranged vertically, dividing the inside of the urease maker 4 into a crude urease solution production area and a urease solution storage area; a urease solution outlet 4-8 is arranged on the side wall of the urease solution storage area; a baffle 4-3 is arranged on the bottom plate of the urease solution production area, and a soybean residue outlet 4-4 is arranged below the baffle 4-3; preferably, a pressure sensor is arranged on the filter screen 4-6. When the pressure reaches the set limit, the pressure sensor transmits a signal to the control system 12, and the control system 12 will give a signal to open the baffle 4-3 to discharge the soybean residue. Preferably, columns 4-7 are further arranged around the bottom of the urease maker for supporting the urease maker 4; a water inlet 4-5 is arranged on the side wall of the urease maker 4.

[0074] In the present invention, the urease solution production system includes a conveying device 2, and the conveying device 2 is used for transporting the soybeans in the soybean storage bin 1 to the urease maker 4; the conveying device 2 may specifically be a conveyor belt.

[0075] In the present invention, the slurry production system includes a cementitious liquid production and storage bin 7; the cementitious liquid production and storage bin 7 is communicated with the second water injection pipe 13.

[0076] In the present invention, the slurry production system includes a slurry maker 9, and a schematic structural diagram of the slurry maker 9 is as Figure 4 shown; the slurry maker 9 includes a mixing tank body 9-4, and a cementitious liquid inlet 9-1, a solid waste inlet 9-2 and a slurry outlet 9-3 are arranged on the mixing tank body 9-4; the cementitious liquid inlet 9-1 is communicated with the outlet of the cementitious liquid production and storage bin 7.

[0077] In the present invention, the slurry production system includes a solid waste storage bin 8; the solid waste storage bin 8 is communicated with the solid waste inlet 9-2 of the slurry maker 9.

[0078] The grouting system provided by the present invention includes a three-way grouting pipe 10; the outlet of the urease maker 4 and the outlet of the slurry maker 9 are respectively communicated with the three-way grouting pipe 10, specifically, are respectively connected to one pipe orifice of the three-way grouting pipe 10, and the other pipe orifice of the three-way grouting pipe 10 is communicated with the gob area.

[0079] In an embodiment of the present invention, in order to achieve the circulation and control of materials in the grouting system, the grouting system of the present invention is further provided with a number of power pumps and flow control valves. Specifically, a first flow control valve 3-1 is preferably provided on the pipeline of the first water injection pipe 6 to control the amount of water injected into the urease producer 4; a first power pump 5-1 and a second flow control valve 3-2 are preferably provided on the pipeline connecting the outlet of the urease producer 4 and the tee grouting pipe 10 to control the output and flow rate of the urease solution; a second power pump 5-2 and a third flow control valve 3-3 are preferably provided on the pipeline of the second water injection pipe 13 to inject water into the cementing liquid production and storage bin 7 and control the flow rate of the water; a third power pump 5-3 and a fourth flow control valve 3-4 are preferably provided on the pipeline connecting the solid waste storage bin 8 and the slurry producer 9 to control the output and flow rate of the solid waste; a fourth power pump 5-4 and a fifth flow control valve 3-5 are provided on the pipeline connecting the outlet of the slurry producer 9 and the tee grouting pipe 10 to control the output and flow rate of the slurry.

[0080] In an embodiment of the present invention, quality control devices are preferably provided in the soybean storage bin 1, the cementing liquid production and storage bin 7, and the solid waste storage bin 8. When the quality of the materials in the soybean storage bin, the cementing liquid production and storage bin, and the solid waste storage bin is low, the quality control device will give an alarm to prompt the operator to replenish in time.

[0081] In an embodiment of the present invention, the grouting system preferably further includes a cloud signal receiver 11 and a control system 12. The control system is specifically a control panel. The control system 12 is used to input control information to control the operation of the grouting system. The cloud signal receiver 11 is used to receive the signal of the coal fire retardant monitoring and early warning system in the goaf and transmit it to the control system 12, so that the grouting system and the coal fire retardant monitoring and early warning system in the goaf form a linkage. When the coal spontaneous combustion monitoring and early warning system monitors that the temperature and the concentration of index gases in the goaf are abnormal, the control system sends a start grouting signal. When the coal spontaneous combustion monitoring and early warning system monitors that the temperature and the concentration of index gases in the goaf return to normal, the control system sends a stop grouting signal. The present invention preferably electrically connects the cloud signal receiver 11 and the coal spontaneous combustion monitoring and early warning system in the goaf to receive the signal of the sensor in the goaf. In a specific embodiment of the present invention, the grouting system can realize signal relay and transmission through the cloud controller 11. When the goaf sensor detects an abnormal signal, it will send an alarm signal. This signal is transmitted to the cloud signal receiver 11 and directly transmitted to the control system 12 after processing. The control system controls the grouting system to perform grouting according to the received alarm signal.

[0082] In the present invention, a coal spontaneous combustion monitoring and early warning system is usually preset in the gob area. Once the internal temperature or the concentration of indicator gases exceeds the limit, an alarm will be triggered. However, taking measures after receiving the alarm often delays the treatment of the fire. In the present invention, the grouting system is linked with the monitoring and early warning system. When the monitoring system alarms, the control system 12 immediately controls the automatic startup of the grouting system to treat the dangerous area in the gob area, and at the same time issues a warning to the staff, thereby improving the treatment efficiency and avoiding the delay of the disaster situation.

[0083] In the present invention, the power pump, flow control valve, and conveying device in the grouting system can be intelligently controlled. Among them, the conveying device 2 is interconnected with the first flow control valve 3-1. Only by inputting the mass ratio of water and soybeans required in the control system 12 can the adjustment be achieved without excessive interference; the fourth flow control valve 3-4 is interconnected with the slurry maker 9 to control the proportion of solid waste; the second flow control valve 3-2 and the fifth flow control valve 3-5 are interconnected. By only inputting the ratio of the urease solution and the slurry required in the control system 12, the power pump can be adjusted to output the corresponding ratio. Most importantly, all components in the grouting system provided by the present invention can be interconnected. By only inputting at the corresponding position in the control system 12, the programs of different working components can be adjusted.

[0084] The present invention also provides a method for grouting using the grouting system described in the above solution, including the following steps:

[0085] Using soybeans and water as raw materials, prepare the urease solution through the urease solution production system;

[0086] Using solid waste, soluble calcium salt, urea, and water as raw materials, prepare the slurry through the slurry production system;

[0087] Introduce the urease solution and the slurry into the three-way grouting pipe 10. The three-way grouting pipe 10 is connected to the gob area, and inject the urease solution and the slurry into the gob area.

[0088] The present invention uses soybeans and water as raw materials to prepare urease solution through the urease solution production system. In a specific embodiment of the present invention, the water used for preparing the urease solution is specifically mine water. By using mine water, the present invention can realize the utilization of abandoned mine water and further reduce costs. The soybeans are preferably output from the soybean outlet 1-1 at the bottom of the soybean storage bin 1 to the conveyor device 2. The conveyor device 2 inputs the soybeans to the feeding port 4-1, and enters the urease maker 4 from the feeding port 4-1. After being crushed by the crusher 4-2, soybean powder is produced. Mine water is input from the water inlet 4-5 to mix with the soybean powder to produce a crude urease solution. After the crude urease solution is retained by the filter screen 4-6, urease solution is produced and enters the urease solution storage area, and then is output from the urease solution outlet 4-8. The dosage ratio of the soybeans and water is the same as the above scheme and will not be elaborated here.

[0089] The present invention uses solid waste, soluble calcium salt, urea and water as raw materials to prepare slurry through the slurry production system; in a specific embodiment of the present invention, the water used for preparing the slurry is specifically mine water; the present invention preferably adds urea and calcium chloride to the cementing liquid production storage bin 7. The mine water enters the cementing liquid maker 7 through the output of the second power pump 5-2 and the control of the third flow control valve 3-3, and then mixes with the urea and soluble calcium salt that have been added in advance to make a cementing liquid. The cementing liquid enters the slurry maker 9. The solid waste in the solid waste storage bin 8 is pumped into the slurry maker 9 through the third power pump 5-3 and the fourth flow control valve 3-4, and converges with the cementing liquid to make slurry, and then is output from the slurry outlet. The concentrations of the solid waste, soluble calcium salt and urea in the slurry are the same as the above scheme and will not be elaborated here.

[0090] In the present invention, after the urease solution is output, it enters the three-way grouting port 10 through the first power pump 5-1 and the second flow control valve 3-2. The slurry enters the three-way grouting port 10 through the fourth power pump 5-4 and the fifth flow control valve 3-5. Here, the slurry and the urease solution converge into the final biological inhibitor material slurry and are injected into the gob area treatment area. In a specific embodiment of the present invention, it is preferred to assemble pipelines in the gob area in advance to facilitate timely work.

[0091] Next, the technical solutions in the present invention will be clearly and completely described in conjunction with the embodiments in the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments in the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

[0092] Example 1

[0093] 1. Test materials

[0094] The coal sample (gas coal) was purchased from Xuzhuang Coal Mine, Datun Company, Peixian County, Jiangsu Province. The soybean (Heihe 43#) was purchased from Tahe County, Daxing'anling Prefecture, Heilongjiang Province, China. Urea (CO(NH2)2, purity ≥ 99.0%), calcium chloride (CaCl2, purity ≥ 96.0%), and calcium formate (Ca(HCOO)2, purity ≥ 96.0%) were purchased from Kelong Chemical Co., Ltd., Chengdu, China.

[0095] 2. Preparation of test samples

[0096] 2.1 Extraction of soybean urease (SUS)

[0097] The soybeans were washed with distilled water to remove impurities, then placed in an oven for drying, and the dried soybeans were crushed using a pulverizer to obtain soybean powder; the soybean powder was mixed with an ethanol solution with a volume fraction of 30% at a solid-liquid ratio of 1 g:10 mL. The mixture was oscillated at 200 rpm for 3 h and then refrigerated for 12 h, and then centrifuged to extract the supernatant to obtain the urease extract. This urease extract was diluted with water to prepare a urease solution, and the volume ratio of the urease extract to water was 1:50. The obtained urease solution was used in the subsequent experiments.

[0098] 2.2 Preparation of cementing liquid

[0099] Preparation of calcium chloride cementing liquid (CES-CC): 1 mol / L urea and 1 mol / L calcium chloride (CC) were mixed at a volume ratio of 1:1 to prepare CES-CC.

[0100] Preparation of calcium formate cementing liquid (CES-CF): 1 mol / L urea and 1 mol / L calcium formate (CF) were mixed at a volume ratio of 1:1 to prepare CES-CF.

[0101] 2.3 Preparation of coal powder

[0102] The fresh coal sample was crushed and screened with a 40-80 mesh sieve, and then placed in a vacuum drying oven and treated at 40 °C for 24 h for subsequent tests.

[0103] 2.4 Preparation of test samples

[0104] The preparation ratio of the test sample materials is shown in Table 1, where FA is fly ash, CS is carbide slag, and the water-cement ratio is 0.65 (i.e., the total volume of the cementing liquid and the soybean urease solution is to the total mass of the coal powder, FA, and CS), and the volume ratio of the soybean urease solution to the cementing liquid is 1:3. The different powder materials were mixed evenly, and CES and SUS were added and stirred evenly, reacted for 24 h, and then dried in an oven at 40 °C for 24 h and stored in a sealed manner.

[0105] Table 1 Preparation ratio of test sample materials

[0106]

[0107] 3. Experimental methods and results

[0108] 3.1 X-ray diffraction analysis (XRD)

[0109] To clarify the crystal structure and properties of the reaction products of the test samples, an X-ray diffractometer was used to determine the types of substances present in the test samples. 50 mg of pulverized coal with a particle size of 200 - 300 mesh was taken for testing. The scanning range was 10° - 90°, and the scanning speed was 10° / min.

[0110] Figure 5 Fig. is the XRD pattern of the test samples. It can be seen from the Coal sample that there are no obvious diffraction peaks of vaterite and calcite, because no cementing liquid was added to the Coal sample. Comparing the Coal-FA-CES-CC-SUS and Coal samples, a very strong SiO2 peak can be observed at 2θ = 26.67° after adding FA, CES-CC, and SUS, indicating that FA contains SiO2. A vaterite-type calcium carbonate peak can be observed at 2θ = 20.92°, which is due to the formation of vaterite after adding CES-CC and SUS. Comparing the Coal-CS-CES-CC-SUS and Coal samples, Ca(OH)2 peaks can be observed at 2θ = 18.09°, 22.96°, 28.68°, 34.06°, and 54.47° after adding CS, SUS, and CES-CC, indicating that CS contains Ca(OH)2 or calcium oxide reacts with water to produce Ca(OH)2. At the same time, calcite-type calcium carbonate peaks can be observed at 2θ = 29.39°, 39.06°, and 47.227°, and a vaterite-type calcium carbonate peak can be observed at 2θ = 50.99°, indicating that calcite-type calcium carbonate and vaterite-type calcium carbonate are produced after adding CES-CC and SUS. Comparing Coal-FA-CS-CES-CC-SUS with Coal, calcite calcium carbonate peaks can be observed at 2θ = 29.39°, 36.059°, 39.06°, and 47.227° after adding FA, CS, SUS, and CES-CC, and a vaterite calcium carbonate peak can be observed at 2θ = 24.957°, indicating that the calcium carbonate formed after adding FA, CS, SUS, and CES-CC is mainly in the stable calcite form, and a small amount of vaterite is produced at the same time.

[0111] Comparing Coal-CES-CC-SUS with Coal-CES-CF-SUS, it can be seen that the calcite-type calcium carbonate characteristic peak signal of the sample with CES-CF-SUS added is stronger at 2θ = 31.32°, and the vaterite-type calcium carbonate signal peak of the sample with CES-CC-SUS added is stronger at 2θ = 32.65°. However, there is no obvious change in the signal intensity of calcite and vaterite when comparing Coal-FA-CS-CES-CC-SUS with Coal-FA-CS-CES-CF-SUS, indicating that better cementation effect is achieved after adding FA and CS.

[0112] 3.2 Infrared Analysis

[0113] Due to the interaction between the active groups in coal and oxygen, heat is generated and continuously accumulates, leading to an increase in temperature. When the temperature of the coal reaches the ignition point, coal spontaneous combustion occurs. One of the functions of adding biological inhibitor materials is to reduce the number of active groups in coal and inhibit its reaction with oxygen to achieve the effect of preventing and extinguishing fires. To explore the molecular structure and chemical composition of the test samples, an infrared spectrometer was used for testing. The particle sizes of the test samples were all 200 - 300 mesh, and they were mixed with KBr and pressed into tablets to make test samples. The scanning range was the mid-infrared region between 4000 - 400 cm -1 and the number of scans was 64 times.

[0114] Figure 6 For the infrared spectral curves (a) and the proportion of functional groups (b) of each test sample in Example 1. According to Figure 6 the following results can be obtained:

[0115] Hydroxyl group: As can be seen from (a) of Figure 6 , free hydroxyl group peaks are generated at 3650 cm -1 for the samples of Coal-CS-CES-CC-SUS, Coal-FA-CS-CES-CC-SUS, and Coal-FA-CS-CES-CF-SUS. Figure 6 Shown in (b) of

[0116] Aliphatic hydrocarbons: FromFigure 6 As can be seen from (a) of -1 , an asymmetric stretching vibration peak of methylene can be observed at 2920 cm -1 , a symmetric stretching vibration peak of methylene in the sample can be observed at 2850 cm -1 , and an asymmetric stretching vibration peak of methyl can be observed at 2960 cm. The molecules in coal mainly exist as long-chain alkanes. Methyl and methylene are one of the main reactive groups participating in the reaction in the macromolecular structure of coal. From Figure 6 As can be seen from (b) of

[0117] Aromatic hydrocarbons: As can be seen from (b) of Figure 6 , the proportion of aromatic hydrocarbons in Coal-CS-CES-CC-SUS, Coal-FA-CS-CES-CC-SUS, Coal-FA-CS-CES-CF-SUS, and Coal-CES-CF-SUS is 1% lower than that in the Coal sample. Aromatic hydrocarbons are organic compounds containing aromatic rings in the carbon chain structure. The relatively unsaturated structure can participate in the pyrolysis reaction more easily under high-temperature conditions, releasing energy and forming more combustible volatile substances, which play a promoting role in the further oxidation reaction. Therefore, adding these biological inhibitor materials can effectively inhibit the occurrence of coal spontaneous combustion.

[0118] Oxygen-containing functional groups: The oxygen-containing functional groups in coal are mainly composed of carbonyl, carboxyl, and ether bonds, and the spectral peak band ranges between 1800 cm -1 ~900 cm -1 . The carboxyl and carbonyl in the oxygen-containing functional groups can combine with oxygen to produce more reactive small molecules to participate in the coal-oxygen reaction. Therefore, the higher the content of carboxyl and carbonyl in the oxygen-containing functional groups, the easier the coal-oxygen reaction occurs. Figure 6As shown in (b), the proportion of oxygen-containing functional groups in the Coal-FA-CES-CC-SUS, Coal-CS-CES-CC-SUS, and Coal-FA-CS-CES-CC-SUS samples decreased by 6%, 6%, and 7% respectively compared to Coal, while the proportion of oxygen-containing functional groups in the Coal-FA-CS-CES-CF-SUS, Coal-CES-CC-SUS, and Coal-CES-CF-SUS samples increased by 5% compared to Coal. Therefore, Coal-FA-CES-CC-SUS, Coal-CS-CES-CC-SUS, and Coal-FA-CS-CES-CC-SUS have greater potential in the treatment of coal spontaneous combustion. Among them, the proportion of oxygen-containing functional groups in Coal-FA-CS-CES-CC-SUS (51%) is the lowest, and it can be speculated that its performance in inhibiting coal spontaneous combustion is better than that of Coal-FA-CES-CC-SUS and Coal-CS-CES-CC-SUS.

[0119] 3.2 Temperature-programmed experiment

[0120] (1) CO gas and inhibition rate

[0121] In order to determine the effect of inhibiting coal spontaneous combustion of test samples during low-temperature oxidation, the crossover temperature, CO concentration, and oxygen concentration during the heating process of different test samples were measured. The test equipment mainly includes a temperature-programmed oven (ZRD-II type coal spontaneous combustion characteristic tester, Shandong Anxin Scientific Instruments Co., Ltd., China) and a gas chromatograph (GC-6900 type gas chromatograph, Shandong Anxin Scientific Instruments Co., Ltd., China). The exhaust gas was collected every 10 °C and the concentrations of CO and O2 in the gas were measured using the gas chromatograph.

[0122] Index gas is one of the important reference indicators for the reaction degree during coal spontaneous combustion. In the present invention, CO is selected as the index gas to judge the severity of coal spontaneous combustion. Figure 7 It shows the variation of the index gas CO of the test sample with temperature. As can be seen from Figure 7 it that before 180 °C, the CO production of Coal-CES-CC-SUS and Coal-CES-CF-SUS is less than that of Coal. This is because a small amount of calcium carbonate is produced after adding SUS and CES with different calcium sources, which forms a thin film on the surface of the coal to a certain extent and plays a role in isolating oxygen. After 180 °C, due to the rapid reaction between coal and oxygen, the amount of calcium carbonate wrapping the coal is insufficient, so that the volume of the coal expands further after heating, resulting in the rupture of the thin film and the weakening of its oxygen isolation effect. The coal that was not previously reacted with oxygen is also exposed to oxygen, leading to a rapid increase in the CO production rate. As can be seen from Figure 7It can be seen that the CO production of Coal-FA-CS-CES-CC-SUS, Coal-FA-CS-CES-CF-SUS, and Coal-FA-CES-CC-SUS is relatively low before 200 °C. This is because they contain a large amount of FA particles, and the SiO2 in them has good heat insulation performance and thermal stability, which can prevent heat transfer during the heating process. Coal-CS-CES-CC-SUS contains a large amount of Ca(OH)2. Under the cementation of calcium carbonate, the formed material can form a dense oxygen isolation layer to prevent the reaction between oxygen and coal. The CO production of Coal-FA-CS-CES-CC-SUS is lower than that of Coal-CS-CES-CC-SUS and Coal-FA-CES-CC-SUS. This is because FA and CS are added simultaneously. The layered Ca(OH)2 and calcite-type calcium carbonate produced by the reaction of soybean urease and the cementing liquid play a good cementing and filling role, adhering the spherical particles provided by FA to the surface of the coal to form a dense protective layer, which can isolate oxygen and heat transfer, so it can effectively inhibit the combustion and heat diffusion of coal.

[0123] The inhibition rate refers to the relative change in the CO released by the coal sample before and after being treated with the biological inhibition material as the evaluation index. The specific calculation formula is as follows:

[0124] Φ = (Q1 - Q2) / Q1 × 100% Equation (1);

[0125] In Equation (1): Φ is the inhibition rate; Q1 is the CO release amount of Coal during the test, ppm; Q2 is the CO release amount of the coal sample after inhibition treatment during the test, ppm.

[0126] The average inhibition rates of the samples at 40 - 80 °C are shown in Table 2. It can be seen from Table 2 that during the oxidation process of the coal samples, Coal-FA-CS-CES-CC-SUS has the best inhibition effect (the average inhibition rate is as high as 73.08%). The inhibition effect of Coal-FA-CS-CES-CF-SUS is better than that of Coal-FA-CES-CC-SUS, Coal-CS-CES-CC-SUS, Coal-CES-CC-SUS, and Coal-CES-CF-SUS, indicating that the inhibition effect of adding FA, CS, SUS, and CES simultaneously in the biological inhibition material is better than that of the samples adding some of the materials, and CES-CC can play a better fire prevention effect compared with CES-CF.

[0127] Table 2 Average inhibition rates of different coal samples at 40 - 200 °C

[0128] Test coal sample Average inhibition rate (%) Coal-FA-CES-CC-SUS 62.36 Coal-CS-CES-CC-SUS 55.58 Coal-FA-CS-CES-CC-SUS 73.08 Coal-FA-CS-CES-CF-SUS 67.91 Coal-CES-CC-SUS 37.03 Coal-CES-CF-SUS 17.58

[0129] (2) Cross-point temperature

[0130] The cross-point temperature refers to the temperature at which the furnace temperature and the tank temperature (the temperature of the coal sample) intersect during a programmed temperature rise test. Before the cross-point temperature, the furnace temperature is higher than the tank temperature because the coal's preheating and temperature rise are relatively slow at the beginning. As the temperature increases, the coal gradually oxidizes, and at the same time, heat is released to initiate a chain reaction, resulting in an accelerating temperature rise rate. When the cross-point is reached, the temperature rise rate of the coal exceeds the ambient temperature rise rate, and the oxidation rate accelerates.

[0131] The cross-point temperatures of the test samples are as Figure 8 shown. According to Figure 8 it can be seen that the cross-point temperature of Coal is the lowest (153.7 °C). After adding different biological inhibitor materials, the cross-point temperatures of the samples all increase, indicating that the selected biological inhibitor materials can inhibit the occurrence of coal spontaneous combustion to varying degrees. The cross-point temperature of Coal-FA-CS-CES-CC-SUS (174.7 °C) is higher than that of Coal-FA-CES-CC-SUS (164.4 °C) and Coal-CS-CES-CC-SUS (165.3 °C), indicating that FA and CS have a synergistic effect on preventing and controlling coal spontaneous combustion, and the inhibition effect is better than using FA or CS alone.

[0132] 3.3 Cone calorimeter test

[0133] The flame retardant performance of the test samples on coal was tested by a cone calorimeter. 10 g of the test sample was evenly spread on a sample trough with tin foil (length × width × height: 100 mm × 100 mm × 100 mm). The initial temperature was 20 °C, the relative humidity was 40%, and the heat radiation intensity was 40 kW·m -2 , and the test time was 600 s.

[0134] (1) Ignition time

[0135] The ignition time (TTI) is the time required for the coal sample to be heated by the cone furnace and an indirect spark provided by an electronic igniter until a stable flame is formed. It mainly reflects the combustibility of the coal. Under the same heat radiation, the longer the TTI, the more difficult it is to heat the coal sample through oxidation, and the lower the possibility of spontaneous combustion. Therefore, TTI plays an important role in reflecting the delay performance. Table 3 shows the ignition and extinction times of the test samples.

[0136] Table 3 Ignition and extinction times of different samples

[0137]

[0138]

[0139] As can be seen from Table 3, the ignition time and extinction time of the Coal sample are 19 s and 120 s respectively. Compared with the Coal sample, except for Coal-CES-CC-SUS, the ignition times of other samples have increased to varying degrees, and the extinction times have decreased. Among them, the ignition times of Coal-CS-CES-CC-SUS and Coal-FA-CS-CES-CC-SUS have increased by 26.3% (24 s), and the extinction times of Coal-FA-CS-CES-CC-SUS and Coal-CS-CES-CC-SUS have decreased by 32.5% (81 s) and 29.1% (85 s). The calcite-type calcium carbonate generated in the FA, CS, CES-CC, SUS composite system cements the fly ash and carbide slag and covers the coal surface to form a protective layer with higher stability to isolate the coal from oxygen contact, thereby inhibiting the oxidation reaction of the coal.

[0140] (2) Heat release rate and total heat release

[0141] The heat release rate (HRR) refers to the heat of combustion per unit time under specified test conditions. The total heat release rate (THR) is the total amount of heat released per unit area of the material from ignition to extinction. HRR and THR are important heat release parameters for evaluating the safety of materials in a fire. The higher the HRR and THR values, the more heat feedback the material receives. Heat feedback causes the material to be pyrolyzed faster, thereby increasing the generation of volatile combustibles and accelerating the spread of the flame. The HRR and THR change curves of the test samples are as Figure 9 shown, Figure 9 in which (a) is the HRR curve and (b) is the THR curve.

[0142] According to Figure 9 it can be seen that the HRR peak value of Coal is 105.54 kW / m 2 , and the samples Coal-FA-CES-CC-SUS (16.93 kW / m 2 ), Coal-FA-CS-CES-CC-SUS (18.81 kW / m 2 ), Coal-CS-CES-CC-SUS (19.97 kW / m 2 ), Coal-FA-CS-CES-CF-SUS (21.63 kW / m 2 ), Coal-CES-CC-SUS (27.36 kW / m 2 ), Coal-CES-CF-SUS (34.95 kW / m 2)The peak HRR values are respectively reduced by 83.96%, 82.18%, 81.08%, 79.51%, 74.08%, and 66.89% compared to Coal. The final THR value of Coal is 1.67 MJ / m 2 . The sample Coal-FA-CES-CC-SUS (0.33 MJ / m 2 ), Coal-FA-CS-CES-CC-SUS (0.39 MJ / m 2 ), Coal-CS-CES-CC-SUS (0.43 MJ / m 2 ), Coal-FA-CS-CES-CF-SUS (0.52 MJ / m 2 ), Coal-CES-CC-SUS (0.35 MJ / m 2 ), and Coal-CES-CF-SUS (1.53 MJ / m 2 ) have final THR values that are respectively reduced by 80.24%, 82.04%, 74.25%, 68.86%, 79.04%, and 8.38% compared to Coal. After adding the biological inhibitor materials, the time from the start to the end of the heat release of the samples increases, and the total heat release amount decreases, which can slow down the intense oxidation heat release process of coal and inhibit the heat transfer process to a certain extent. The Coal-FA-CES-CC-SUS sample has the lowest peak HRR value and final THR value, indicating that adding FA to coal can play a good heat insulation role. Except for the Coal-FA-CES-CC-SUS sample, the Coal-FA-CS-CES-CC-SUS sample has the lowest peak HRR value and final THR value among all samples. The reason is that the sample contains CS, which enhances the plugging effect after being mixed with FA, CES, and SUS, and prevents the longitudinal transfer of temperature, ultimately achieving the purpose of heat insulation and flame retardancy.

[0143] (3) Generation and Concentration Variation Law of CO Index Gas

[0144] The amount of CO generated during the low-temperature oxidation process of coal indicates the severity of coal oxidation. The relationship between CO and combustion time during the test of the test samples is shown as Figure 10 . As shown from Figure 10It can be seen that Coal, Coal-CES-CC-SUS, and Coal-CES-CF-SUS have two CO peaks, the reason for which is related to the two combustion stages of coal. There is only one CO peak in Coal-FA-CES-CC-SUS, Coal-CS-CES-CC-SUS, Coal-FA-CS-CES-CC-SUS, and Coal-FA-CS-CES-CF-SUS, indicating that the functional groups of the coal samples are changed by the biological inhibitor materials, resulting in changes in the combustion heat release process of different samples. The initial CO release time of Coal is 37 s. Compared with Coal, the initial CO release times of Coal-FA-CES-CC-SUS, Coal-CS-CES-CC-SUS, Coal-FA-CS-CES-CC-SUS, Coal-FA-CS-CES-CF-SUS, Coal-CES-CC-SUS, and Coal-CES-CF-SUS are delayed by 16 s, 75 s, 62 s, 24 s, 10 s, and 7 s respectively (the initial CO release times are 53 s, 112 s, 99 s, 61 s, 47 s, and 44 s respectively). The peak CO release amount of Coal is 0.015%. Compared with Coal, the peak CO release amounts of Coal-FA-CES-CC-SUS, Coal-CS-CES-CC-SUS, Coal-FA-CS-CES-CC-SUS, Coal-FA-CS-CES-CF-SUS, Coal-CES-CC-SUS, and Coal-CES-CF-SUS are reduced by 33.3%, 6.7%, 66.7%, 46.7%, and 2% respectively (the peak CO release amounts are 0.01%, 0.005%, 0.005%, 0.008%, 0.0147%, and 0.013% respectively). After adding the biological inhibitor materials, the initial CO release time of the samples increases, and the peak CO release amount decreases. It can be determined that the biological inhibitor materials slow down the thermal decomposition of coal and the reaction process with oxygen, and inhibit the occurrence of the coal-oxygen composite reaction. Among them, the peak CO release amount of Coal-CS-CES-CC-SUS is reduced the most compared with the Coal sample. Therefore, the biological inhibitor materials formed by FA, CS, CES-CC, and SUS significantly reduce the severity of coal oxidation and have the best fire prevention and extinguishing effect.

[0145] (4) Flue gas generation rate and total smoke release amount

[0146] The smoke generation rate and cumulative smoke release amount of the test samples are as Figure 11 shown in Figure 11 , where (a) is the smoke generation rate and (b) is the total smoke release amount. As can be seen from Figure 11 , the maximum smoke generation rate of the sample Coal is 0.0906 m 2 / s, the total smoke production is 3.982 m 2 , and the smoke production rate and total smoke production of the coal samples treated with the biological inhibitor material decreased significantly. The maximum smoke production rate of the Coal-CS-CES-CC-SUS sample decreased by 79.8% (0.0183 m 2 / s), and the total smoke production decreased by 89.9% (0.4019 m 2 ). The maximum smoke production rate of the Coal-FA-CS-CES-CC-SUS sample decreased by 69.3% (0.0278 m 2 / s), and the total smoke production decreased by 81.9% (0.7197 m 2 ). Thus, it can be determined that the biological inhibitor material of the present invention has a good inhibitory effect on the smoke production process of coal spontaneous combustion.

[0147] Combined with indicators such as ignition time, heat release rate, total heat release, generation and concentration change law of CO index gas, it can be determined that compared with other materials, the biological inhibitor material in the Coal-FA-CS-CES-CC-SUS sample has better performance in preventing coal spontaneous combustion and inhibiting coal combustion.

[0148] 3.4 Fire extinguishing test

[0149] An independent fire extinguishing simulation test device was built. The test device consists of 3 thermocouples (range: 0 - 1200 °C; accuracy: ±0.75%), a data acquisition device and a metal bracket. The 3 thermocouples (T1, T2, T3) are fixed on the metal bracket from bottom to top. T3 is located above the top of the coal block, T2 is located in the middle of the coal block, and T1 is located below the bottom of the coal block. Prepare the fire extinguishing materials according to the ratio in Table 4, and choose honeycomb coal for the fire extinguishing test. The fire extinguishing simulation test platform is as Figure 12 shown. First, heat two coal balls on the heating furnace for 45 minutes to make them reach a fully burning state, then put the coal balls into the iron combustion chamber, insert thermocouples at the top, middle and bottom positions of the two coal balls respectively. The thermocouples convert the thermal signal into an electrical signal and record the temperature change data through the acquisition card. When observing that the temperature of the middle thermocouple reaches 650 °C, start recording the data. When the temperature of the middle thermocouple reaches 700 °C, quickly add 500 mL of fire extinguishing material from the upper part of the combustion chamber, and record the temperature change of different positions of the coal within 1000 s. Each group of tests is repeated 3 times, and the test results are averaged.

[0150] Table 4 Material ratio of fire extinguishing materials for fire extinguishing test

[0151]

[0152] The fire extinguishing test results of the fire extinguishing materials are as Figure 13 shown in and Table 5.

[0153] Table 5 Temperature Monitoring 1000 s after the Fire Extinguishing Experiment

[0154] Sample Final top temperature °C Final middle temperature °C Final bottom temperature °C FET-WA 378 669.2 81.4 FET-FA-CES-CC-SUS 389 693.7 130.4 FET-CS-CES-CC-SUS 93.2 546.7 307.6 FET-FA-CS-CES-CC-SUS 66.1 300.5 206.9 FET-FA-CS-CES-CF-SUS 82.5 434.6 218.8 FET-CES-CC-SUS 527.4 961.6 146.9 FET-CES-CC-SUS 459.5 935.3 389.5

[0155] Figure 13 As shown in (a), when extinguishing the fire of the briquette through FET-WA, the temperatures at the top, middle, and bottom of the briquette rapidly decrease to 98 °C. After 150 s, the temperatures at the top and middle rise to 383 °C and 202 °C respectively. After 1000 s, the temperatures at the top and middle rise to 669 °C and 377 °C respectively. This is because after adding water, when water contacts the coal in a high-temperature state, it will evaporate and take away part of the heat. However, there is less water remaining on the surface of the coal, and there is still a high amount of heat inside the coal after the water evaporates, which leads to the re-ignition of the coal. From Figure 13 As can be observed from (a), after adding water, a large amount of water will be lost from the wire mesh at the bottom of the combustion chamber, and the middle part of the coal is still in a red-hot state after 1000 s. From Figure 13 As can be seen from (a), (f), and (g), when using water, FET-CES-CC-SUS, and FET-CES-CF-SUS to extinguish the fire, the temperature changes show a similar trend.

[0156] Figure 13 As shown in (b), re-ignition still occurs after adding FET-FA-CES-CC-SUS. At 1000 s, the temperatures at the top and middle are 693 °C and 382 °C respectively. This is because FA contains a large number of spherical FA particles, which increases the fluidity of the slurry. Therefore, it cannot be retained in large quantities on the briquette with intense combustion to play the role of extinguishing the fire. As shown in the figure, after 370 s, the temperature at the top is higher than that at the bottom because after the fire extinguishing material flows to the bottom of the briquette with intense combustion, it accumulates, preventing the oxygen at the bottom from continuing to react with the briquette. Therefore, the temperature at the bottom is lower than that at the top.

[0157] Figure 13 As shown in (c), after adding the FET-CS-CES-CC-SUS fire extinguishing material, at 1000 s, the temperature at the top drops sharply and remains at 90 °C, the temperature in the middle drops slowly to 547 °C, while the temperature at the bottom first rises rapidly to 614 °C and then drops slowly to 307 °C. This is because CS contains a large amount of calcium oxide. After being mixed with SUS and CES, the water therein reacts with calcium oxide, so the viscosity increases. After the fire extinguishing material is added to the combustion furnace, a tight sealing structure is formed in the upper part. At the same time, the evaporation of water absorbs heat and the volume of the material shrinks, which can wrap more densely around the top of the briquette. Therefore, the temperature at the top drops rapidly. After the upper part is blocked, the heat flow in the coal flows out from the lower part. After a period of time, the combustion effect of the coal weakens. Therefore, the phenomenon of the temperature in the middle of the briquette dropping slowly and the temperature at the lower part rising rapidly first and then dropping slowly occurs. From Figure 13As can be seen from Fig. (c), after adding the fire extinguishing material, due to the too high viscosity, no fire extinguishing material flows out at the bottom of the combustion chamber, and it is shown in the picture after extinguishing that the fire extinguishing material accumulates on the upper part of the briquette.

[0158] Figure 13 As shown in Fig. (d), after adding the FET-CS-FA-CES-CC-SUS fire extinguishing material, the temperatures at the top, middle and bottom of the briquette all drop rapidly. At 1000 s, the temperatures at the top and middle are stabilized at 66 °C and 300 °C. Compared with other samples, the temperature in the middle is at the minimum value at the end of the test and shows no upward trend, indicating that the fire extinguishing material can be retained in the upper and middle parts of the briquette, and can effectively cool and extinguish the coal body on fire in the middle. The temperature at the bottom is 204 °C and still shows a downward trend. The SiO2 in FA has good heat insulation performance and thermal stability, which can reduce the heat transfer of the flame to the surrounding environment and slow down the spread rate of the fire. Figure 13 As shown in Fig. (d), after adding the material, less slurry flows out at the bottom. After extinguishing, there is no obvious red-hot phenomenon on the briquette, and the slurry is evenly and densely distributed on the upper part of the briquette, indicating that this material has good fire extinguishing effect.

[0159] According to Figure 13 By comparing the data in Fig. (e), (d) and Table 7, it can be seen that the fire extinguishing effect of FET-FA-CS-CES-CC-SUS is better than that of FET-FA-CS-CES-CF-SUS. After adding FET-FA-CS-CES-CF-SUS, the temperatures at the top, middle and bottom drop rapidly to 208 °C. However, after a period of time, the temperatures in the middle and bottom rise rapidly again. At 1000 s, the temperatures in the middle and bottom are 434 °C and 219 °C, which are 134.1 °C and 11.9 °C higher than those in the middle and bottom of FET-FA-CS-CES-CC-SUS, indicating that the briquette has a tendency to reignite after being extinguished by this fire extinguishing material for the briquette with intense combustion; Figure 13 In Fig. (e), after adding FET-FA-CS-CES-CF-SUS, the fire extinguishing material flowing out at the bottom of the combustion chamber is significantly more than Figure 13 the sample FET-FA-CS-CES-CC-SUS in Fig. (d), and the plugging effect of the top hole is not as good as Figure 13 that in Fig. (d). The reason is that compared with FET-FA-CS-CES-CC-SUS, it has better adhesion to FA particles, enabling it to adhere to the coal wall in large amounts and not easily flow away, so the fire extinguishing effect is better.

[0160] Example 2

[0161] Adopt Figure 1 the grouting system in

[0162] When the system starts to work, the urease solution production system and the slurry production system work simultaneously. When the urease solution production system starts to work, the soybeans in the soybean storage bin 1 are output through the soybean outlet 1-1 onto the conveyor device 2, and then enter through the feeding port 4-1 above the urease maker 4. After being crushed by the crusher 4-2 to produce soybean powder, mine water is input through the water inlet 4-5 to mix with the soybean powder to produce a crude urease solution. After being retained by the filter screen 4-6, the produced urease solution enters the urease storage area. There is also a pressure sensor on the filter screen. When the pressure reaches the set limit, the baffle 4-3 will be opened and the soybean dregs will be discharged. After the urease solution (denoted as SUS solution) is output, it enters the three-way grouting port 10 through the first power pump 5-1 and the second flow control valve 3-2. During the production process of the urease solution, the mass ratio of soybeans to mine water is controlled at 1:10.

[0163] When the slurry production system works, the mine water is output through the second power pump 5-2, and the flow rate is controlled by the third flow control valve. The mine water enters the cementing liquid maker 7, and then mixes with the pre-added urea and calcium chloride to make the cementing liquid, and then enters the slurry maker 9. Here, the carbide slag fly ash in the solid waste storage bin 8 is pumped in through the third power pump 5-3 and the fourth flow control valve 3-4 to converge with the cementing liquid to make the slurry (denoted as FA-CS-CES-CC slurry), and then enters the three-way grouting port 10 underground under the action of the fourth power pump 5-4 and the fifth flow control valve 3-5. Here, the FA-CS-CES-CC slurry and the SUS solution converge into the final slurry and are injected into the dangerous area that needs to be treated in the goaf. During injection, the volume ratio of the FA-CS-CES-CC slurry to the SUS solution is controlled at 3:1. In the finally obtained FA-CS-CES-CC slurry, the total content of fly ash and carbide slag (the added mass ratio of fly ash to carbide slag is 1:1) is 510 g / L, the concentration of calcium chloride is 1 mol / L, and the concentration of urea is 1 mol / L.

[0164] Each power pump, flow control valve, and conveying device in the grouting system of the present invention are intelligently controlled by the control system 12. Among them, the conveying device 2 is interconnected with the first flow control valve 3-1. By inputting the mass ratio of mine water and soybeans required in the control system 12, the usage amounts of soybeans and mine water can be adjusted without excessive interference. The fourth flow control valve 3-4 is interconnected with the slurry maker 9 to control the ratio of fly ash and carbide slag. The second flow control valve 3-2 and the fifth flow control valve 3-5 are interconnected. By inputting the ratio of the required SUS solution and the FA-CS-CES-CC slurry in the control system 12, the first power pump 5-1 and the fourth power pump 5-4 are adjusted to output the SUS solution and the FA-CS-CES-CC slurry in the corresponding ratio. In addition, the soybean storage bin 1, the cementing liquid production and storage bin 7, and the solid waste storage bin 8 are equipped with quality control devices. When the quality in the bin is low, the quality control device will issue an alarm to prompt the staff to replenish in time.

[0165] In summary, the present invention first uses the soybean urease-induced carbonate precipitation technology to cement solid wastes such as fly ash and carbide slag, providing a new type of biological inhibitor material for preventing coal spontaneous combustion in goafs. This biological inhibitor material has a high inhibition rate and good fire extinguishing effect. At the same time, the present invention also provides a grouting system, which has a high degree of integration, is easy to operate, has high working efficiency, can realize the intelligent preparation of biological inhibitor materials and the intelligent control of the perfusion amount, without manual assistance, saving a large amount of manpower and material resources. The biological inhibitor material and the grouting system provided by the present invention have extremely high application potential in the prevention and control of coal spontaneous combustion disasters.

[0166] The above are only the preferred embodiments of the present invention. It should be noted that for those of ordinary skill in the art, without departing from the principle of the present invention, several improvements and refinements can be made, and these improvements and refinements should also be regarded as the protection scope of the present invention.

Claims

1. A biological inhibitor material, characterized in that, It includes component A and component B; The component A consists of the following components in parts by mass: 500 - 2500 parts of solid waste, 40 - 360 parts of soluble calcium salt, and 20 - 125 parts of urea; the solid waste includes one or more of fly ash, carbide slag, red mud, blast furnace slag, mine sludge, and steel slag; The component B includes urease.

2. The bio-inhibiting material according to claim 1, wherein The solid waste is fly ash and carbide slag, and the mass ratio of fly ash to carbide slag is 1:0.5 - 1.3; the soluble calcium salt includes one or more of calcium chloride, calcium formate, calcium nitrate, and calcium acetate; the urease is soybean urease.

3. Application of the biological inhibitor material according to any one of claims 1 or 2 in preventing and controlling coal spontaneous combustion in goaf.

4. The application according to claim 3, wherein The method of the application includes: Mixing the solid waste, soluble calcium salt, urea, and water to obtain a slurry; Injecting the slurry and urease solution into the area to be treated in the goaf.

5. The application according to claim 4, wherein The preparation method of the urease solution includes method one or method two. Method one includes: crushing soybeans and mixing them with water, and then filtering to obtain the urease solution; the mass ratio of soybeans to water in method one is 0.9 - 1.2:10; Method two includes: crushing soybeans and mixing them with an ethanol aqueous solution for oscillation, then refrigerating and centrifuging in sequence to obtain a urease extract, and mixing the urease extract with water to obtain the urease solution; the dosage ratio of soybeans to the ethanol aqueous solution in method two is 1g:8 - 15mL, and the volume ratio of the urease extract to water is preferably 1:35 - 68; The content of the solid waste in the slurry is 500 - 2500g / L, the concentration of the soluble calcium salt is 0.4 - 2mol / L, and the concentration of urea is 0.4 - 2mol / L; The volume ratio of the slurry to the urease solution is 2.7 - 3.2:

1.

6. A grouting system, characterized in that, It includes a urease solution production system, a slurry production system, and a three-way grouting pipe: The urease solution production system includes: A soybean storage bin; a soybean outlet is provided at the bottom of the soybean storage bin; A urease producer; the urease producer is connected to a first water injection pipe; A conveying device; the conveying device is used to transport the soybeans in the soybean storage bin to the urease producer; The slurry production system includes: A cementing liquid production and storage bin; the cementing liquid production and storage bin is connected to a second water injection pipe; A slurry producer; the slurry producer includes a mixing tank body, and a cementing liquid inlet, a solid waste inlet, and a slurry outlet are provided on the mixing tank body; the cementing liquid inlet is connected to the outlet of the cementing liquid production and storage bin; A solid waste storage bin; the solid waste storage bin is connected to the solid waste inlet of the slurry producer; The outlet of the urease producer and the outlet of the slurry producer are respectively connected to the three-way grouting pipe.

7. The grouting system according to claim 6, characterized in that, A first flow control valve is provided on the pipeline of the first water injection pipe; A first power pump and a second flow control valve are provided on the pipeline connecting the outlet of the urease producer and the three-way grouting pipe; A second power pump and a third flow control valve are provided on the pipeline of the second water injection pipe; A third power pump and a fourth flow control valve are provided on the pipeline connecting the solid waste storage bin and the slurry producer; A fourth power pump and a fifth flow control valve are provided on the pipeline where the outlet of the slurry maker is connected to the three-way grouting pipe.

8. The grouting system according to claim 6, characterized in that, A feed inlet is provided at the top of the urease maker, and the end of the conveying device is connected to the feed inlet; a crusher and a filter screen are provided inside the urease maker, the filter screen is vertically arranged, dividing the inside of the urease maker into a crude urease solution production area and a urease solution storage area; a urease solution outlet is provided on the side wall of the urease solution storage area; a baffle is provided on the bottom plate of the urease solution production area, and a soybean residue outlet is provided below the baffle. The bottom of the tank body of the soybean storage bin is conical, and the soybean outlet is located above the front end of the conveying device.

9. The grouting system according to claim 6, characterized in that, Quality control devices are provided in the soybean storage bin, the cementing liquid production and storage bin, and the solid waste storage bin. The grouting system further includes a cloud signal receiver and a control system; the control system is used to input control information to control the operation of the grouting system. The cloud signal receiver is used to receive the signal of the coal spontaneous combustion monitoring and early warning system in the goaf and transmit it to the control system, so that the grouting system and the coal spontaneous combustion monitoring and early warning system in the goaf form a linkage; when the coal spontaneous combustion monitoring and early warning system monitors abnormal temperature and index gas concentration in the goaf, the control system sends a start grouting signal, and when the coal spontaneous combustion monitoring and early warning system monitors that the temperature and index gas concentration in the goaf return to normal, the control system sends a stop grouting signal.

10. A method for grouting using the grouting system according to any one of claims 6 to 9, characterized in that, Including the following steps: Using soybean and water as raw materials, preparing urease solution through the urease solution preparation system. Using solid waste, soluble calcium salt, urea and water as raw materials, preparing slurry through the slurry preparation system. Injecting the urease solution and the slurry into the three-way grouting pipe, the three-way grouting pipe is connected to the goaf, and injecting the urease solution and the slurry into the goaf.

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