Fire extinguishing material for mine and preparation method thereof

Abstract

The application relates to the technical field of fire extinguishing materials, and discloses a mine-used fire preventing and extinguishing material and a preparation method thereof. The mine-used fire preventing and extinguishing material is prepared from the following raw materials in parts by weight: 30-40 parts of sulphoaluminate cement, 20-25 parts of acid-activated coal gangue, 5-10 parts of bentonite-based composite phase change body, 3-5 parts of hollow glass microbeads, 0.5-1 part of polypropylene fiber, 3-4 parts of chitosan-acrylic acid copolymer, 1-2 parts of foaming agent, 2-3 parts of expanded graphite, 1-3 parts of zinc borate, 2-4 parts of nano silicon dioxide and 260-320 parts of water. The mine-used fire preventing and extinguishing material provided by the application improves the performance stability in high-temperature fire preventing and extinguishing and the storage stability in the storage process.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of fire extinguishing materials, in particular to a fire extinguishing material for mines and a preparation method thereof. BACKGROUND

[0002] As an important place for mining mineral resources such as coal, the safety production of mines is of great importance. However, mine fire has been one of the major disasters threatening the safety production of mines. Mine fire not only leads to the burning of a large amount of coal resources, causing huge economic losses, but also produces high temperature, toxic and harmful gases and smoke, seriously threatening the life safety of underground workers, and even may cause secondary disasters such as gas explosion, further expanding the influence range of the accident. Therefore, the development of efficient and reliable fire extinguishing materials for mines has important practical significance for preventing and controlling the occurrence of mine fire and ensuring the safety production of mines.

[0003] However, the existing fire extinguishing materials for mines have many limitations in actual application. Taking some gel materials as an example, such materials have good heat insulation and oxygen insulation performance at room temperature, which can effectively prevent the spread of fire. However, in high temperature environment, the gel material is prone to dehydration. With the loss of water, the structure of the gel is gradually destroyed, and its heat insulation and oxygen insulation effect is also lost. Therefore, such gel materials may only be suitable for coal spontaneous combustion prevention and control in low temperature environment. In the initial stage of coal spontaneous combustion, the temperature is relatively low, and the gel material can play a good effect, but as the development of coal spontaneous combustion, the temperature rises, and the gel material cannot maintain good fire extinguishing performance, which is difficult to meet the fire extinguishing demand of high temperature fire. In addition to the instability of performance in high temperature, the stability of the existing fire extinguishing materials is also insufficient in other aspects. Some fire extinguishing materials are prone to physical or chemical changes during storage, resulting in performance degradation. Based on this, the present application proposes a fire extinguishing material for mines and a preparation method thereof. SUMMARY

[0004] The present application proposes a fire extinguishing material for mines and a preparation method thereof, which improves the problem that the existing fire extinguishing materials for mines are prone to dehydration and structure damage in high temperature environment, resulting in loss of heat insulation and oxygen insulation performance, and improves the performance stability of the material in high temperature fire extinguishing. The present application improves the problem that the existing fire extinguishing materials are prone to physical or chemical changes during storage, resulting in performance degradation, and improves the storage stability and comprehensive fire extinguishing performance of the material.

[0005] The technical scheme of the present application is as follows:

[0006] The application discloses a fire extinguishing and preventing material for a mine, which is prepared from the following raw materials in parts by weight: 30-40 parts of sulphoaluminate cement, 20-25 parts of acid-activated coal gangue, 5-10 parts of bentonite-based composite phase change body, 3-5 parts of hollow glass microbeads, 0.5-1 part of polypropylene fiber, 3-4 parts of chitosan-acrylic acid copolymer, 1-2 parts of foaming agent, 2-3 parts of expanded graphite, 1-3 parts of zinc borate, 2-4 parts of nano silicon dioxide and 260-320 parts of water.

[0007] As a further technical scheme, the preparation method of the acid-activated coal gangue comprises the following steps: drying coal gangue at 100-110 DEG C for 2-3 hours, crushing the dried coal gangue to 200 mesh, mixing the crushed coal gangue with a 10% sulfuric acid solution in a solid-liquid ratio of 1g:3-4mL, stirring at a temperature of 80 DEG C plus or minus 2 DEG C and a speed of 180-220 rpm for 2-3 hours, separating and washing by vacuum filtration, placing the acid-washed coal gangue in a muffle furnace, heating at a speed of 5 DEG C per minute to 560-600 DEG C, keeping the temperature constant for 50-70 minutes, naturally cooling to room temperature, grinding to a particle size of less than or equal to 50 microns, and obtaining the acid-activated coal gangue.

[0008] As a further technical scheme, the preparation method of the bentonite-based composite phase change body comprises the following steps: mixing bentonite, anhydrous sodium sulfate and water, ultrasonic dispersion for 30-40 minutes to form a uniform suspension, transferring the suspension to a constant-temperature reaction kettle, stirring at 60 DEG C plus or minus 1 DEG C and a speed of 400-500 rpm for 3-4 hours, centrifugal separation, vacuum drying the precipitate at 70-80 DEG C for 10-12 hours, and grinding and sieving the dried material through a 200 mesh sieve to obtain the bentonite-based composite phase change body.

[0009] As a further technical scheme, the weight ratio of the bentonite, the anhydrous sodium sulfate and the water is 3-4:1-2:20-30.

[0010] As a further technical scheme, the preparation method of the chitosan-acrylic acid copolymer comprises the following steps: adding chitosan into a 2%-3% acetic acid solution, stirring at a speed of 500-600 rpm for 20-30 minutes, accelerating the dissolution of the chitosan by heating to 50-55 DEG C to form a chitosan solution, dropping acrylic acid monomer into the chitosan solution at a speed of 1 mL per minute, adding potassium persulfate initiator to initiate the reaction, cooling to room temperature, and adjusting the pH to 7 plus or minus 0.2, and obtaining the chitosan-acrylic acid copolymer after spray drying.

[0011] As a further technical scheme, the weight ratio of the chitosan, the acetic acid solution, the acrylic acid monomer and the potassium persulfate is 50-60g:900-1100mL:140-160g:2-3g.

[0012] As a further technical scheme, the reaction is carried out under nitrogen protection, at a speed of 200-300 rpm and a temperature of 60 DEG C plus or minus 1 DEG C for 3-4 hours.

[0013] As a further technical solution, the inlet air temperature of the spray drying is 170-180℃, the outlet air temperature is 80-90℃, and the atomization pressure is 0.2-0.3MPa.

[0014] As a further technical solution, the foaming agent comprises cement foaming agent and silicone foam stabilizer in a weight ratio of 1:0.2-0.5.

[0015] In a second aspect, the application provides a preparation method of a mine fire extinguishing material, comprising the following steps:

[0016] (1) Add sulphoaluminate cement, acid-activated coal gangue, nano-silica, zinc borate and expanded graphite into half of the weight of water in sequence, and stir at 700-800rpm for 10-15min to form a uniform slurry;

[0017] (2) Add chitosan-acrylic acid copolymer, and adjust the stirring speed to 400-500rpm for 5-10min; add polypropylene fiber and hollow glass microspheres after pre-mixing, and stir at 500-600rpm for 3-5min; add bentonite-based composite phase change body, and stir at 300-400rpm for 2-4min;

[0018] (3) Add foaming agent and the remaining weight of water, and stir at 200-300rpm for 15-20min to obtain the product.

[0019] The working principle and beneficial effects of the application are as follows:

[0020] The acid-activated coal gangue is introduced into the mine fire extinguishing material to replace the traditional unactivated coal gangue. The acid washing process removes impurities on the surface of the coal gangue, exposes more active sites, significantly improves the surface activity, enhances the interfacial bonding force between the coal gangue and the cement matrix, makes the internal structure of the material more compact, and effectively improves the compressive strength of the material. The calcination process promotes the formation of a porous structure inside the coal gangue, which not only increases the specific surface area of the material, but also improves the adsorption capacity of oxygen and combustible gas, enhances the resistance performance, and the porous structure itself has good thermal stability, which can buffer temperature stress in high temperature environment and reduce cracks caused by uneven thermal expansion of the material.

[0021] In addition, the acid-activated coal gangue has both cementing activity and adsorption function, and cooperates with other components in the material system. Its cementing activity helps to form a stable material skeleton, and its adsorption function can effectively adsorb and fix the resistance components, so that the resistance components are uniformly dispersed in the material, improving the thermal stability and resistance performance of the material. If the coal gangue is not acid-activated (such as Comparative Examples 1 and 2), the material skeleton is loose, the resistance components are not uniformly dispersed, and the thermal stability is significantly deteriorated.

[0022] The present application utilizes bentonite and anhydrous sodium sulfate to prepare a bentonite-based composite phase change body and apply it to mine fire extinguishing and preventing materials, replacing ordinary bentonite, which has unique phase change energy storage characteristics. In a high temperature environment, the phase change material undergoes phase change to absorb heat, effectively buffering temperature stress, preventing the material from dehydrating and cracking due to excessive temperature, and significantly improving the high temperature stability of the material. Ordinary bentonite lacks this phase change energy storage capability (such as Comparative Example 3), and cannot adjust the temperature by phase change heat absorption, resulting in easy dehydration and cracking of the material at high temperature, and a decrease in storage stability. In addition, the bentonite-based composite phase change body plays a role of a structure stabilizer in the material system. It is uniformly dispersed in the material and can adjust the internal stress distribution of the material through the phase change process when the temperature changes, reducing the generation of cracks caused by the difference in thermal expansion coefficient. At the same time, the composite phase change body interacts with other inorganic-organic components in the material to form a stable structure system, enhancing the overall strength and stability of the material. If there is no bentonite-based composite phase change body in the material (such as Comparative Example 4), the material loses the heat management capability, the water evaporates quickly, the structure collapses, and the synergistic effect of inorganic-organic components is also weakened.

[0023] The present application also synthesizes chitosan-acrylic acid copolymer and applies it to mine fire extinguishing and preventing materials, replacing other polymers such as sodium alginate. Chitosan-acrylic acid copolymer has good film-forming property, which can form a dense protective film on the surface of the material, effectively preventing the penetration of oxygen and flammable gas, and improving the resistance performance of the material. At the same time, the active groups in its molecular structure have chelating effect, which can form stable chelates with metal ions and other components in the resistance agent, realizing the slow release of the resistance agent and prolonging the resistance time. After replacing chitosan-acrylic acid copolymer with sodium alginate (such as Comparative Example 5), the resistance agent slow release ability decreases due to the lack of such film-forming property and chelating effect, and the fiber-matrix interface adhesion is weakened, resulting in a decrease in material performance. It also plays a role of an interface adhesive in the material system, which can form a good interface bond with components such as polypropylene fibers and hollow glass microspheres, enhancing the adhesion between fibers and matrix, and improving the overall strength and toughness of the material. This interface adhesion helps to maintain the structural integrity of the material when the material is subjected to external force or temperature change, reducing the generation and expansion of cracks.

[0024] The expanded graphite and zinc borate are used in combination in the present application to exert a synergistic flame-retardant effect. The expanded graphite can rapidly expand to form a dense heat-insulating layer at high temperature, effectively preventing heat transfer and oxygen diffusion, and thus physically blocking the spread of fire. The zinc borate decomposes to generate non-combustible gas at high temperature, diluting the concentration of combustible gas, and at the same time, the decomposition products of the zinc borate cover the surface of the material, thus chemically retarding combustion. The two components synergistically prevent the spread of fire by physical blocking and inhibit the combustion reaction by chemical flame-retardant effect, significantly improving the flame-retardant performance of the material. If the expanded graphite is replaced by zinc borate (such as Comparative Example 6), only the chemical flame-retardant effect of single zinc borate is relied on, and the physical blocking effect of the expanded graphite is lacking, so the flame-retardant rate is obviously reduced and the high-temperature mass loss rate is high. DETAILED DESCRIPTION

[0025] The technical solutions in the embodiments of the present application will be clearly and completely described below in combination with the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor are within the scope of protection of the present application. It should be noted that the cement foaming agent in the present application is model LG-2258, produced by Shandong Yousuo Chemical Technology Co., Ltd.; the silicone foam stabilizer is model YT-MPS, purchased from Dongying Yitong Chemical Co., Ltd.; the polypropylene fiber has a length of 6 mm and a diameter of 15-48 μm, and is purchased from Shandong Jinhuyao Engineering Material Co., Ltd.

[0026] Embodiment 1

[0027] The fire-preventing and extinguishing material for mine provided in the present embodiment is composed of the following raw materials in parts by weight: sulphoaluminate cement 35 parts, acid-activated coal gangue 22 parts, bentonite-based composite phase change body 8 parts, hollow glass microbeads 4 parts, polypropylene fiber 0.8 part, chitosan-acrylic acid copolymer 3.5 parts, foaming agent 1.5 parts, expanded graphite 2.5 parts, zinc borate 2 parts, nano-silicon dioxide 3 parts, and water 290 parts.

[0028] The preparation method of the acid-activated coal gangue comprises the following steps: drying the coal gangue at 105 ℃ for 2.5 h, crushing the dried coal gangue to 200 mesh, mixing the crushed coal gangue with a 10% sulfuric acid solution at a solid-liquid ratio of 1 g:3.5 mL, stirring at a temperature of 80 ℃ and a speed of 200 rpm for 2.5 h, separating and washing by vacuum filtration, placing the acid-washed coal gangue in a muffle furnace, heating at a rate of 5 ℃ / min to 580 ℃, maintaining the temperature for 60 min, naturally cooling to room temperature, and grinding to an average particle size of 40 μm to obtain the acid-activated coal gangue.

[0029] The preparation method of the bentonite-based composite phase change body comprises the following steps: mixing bentonite, anhydrous sodium sulfate and water; ultrasonic dispersion is performed at a power of 500 W and a frequency of 40 kHz for 35 min to form a uniform suspension; the suspension is transferred to a constant-temperature reaction kettle, and stirring is performed at 60 DEG C and 450 rpm for 3.5 h; centrifugal separation is performed at 8000 rpm for 10 min, and the precipitate is vacuum dried at 75 DEG C for 11 h; after drying, the material is ground and sieved through a 200-mesh sieve to obtain the bentonite-based composite phase change body; the weight ratio of bentonite, anhydrous sodium sulfate and water is 3.5:1.5:25;

[0030] The preparation method of the chitosan-acrylic acid copolymer comprises the following steps: 55 g of chitosan is added to 1000 mL of an acetic acid solution with a volume concentration of 2.5%, and stirring is performed at 550 rpm for 25 min; the temperature is increased to 52 DEG C to accelerate dissolution to form a chitosan solution; 150 g of acrylic acid monomer is added dropwise to the chitosan solution at a rate of 1 mL / min, and 2.5 g of potassium persulfate initiator is added at the same time; the reaction is performed at 250 rpm and 60 DEG C for 3.5 h under the protection of nitrogen; after cooling to room temperature, a 10% NaOH solution is slowly added to neutralize the solution to adjust the pH to 7; spray drying is performed by controlling the air inlet temperature to be 175 DEG C, the air outlet temperature to be 85 DEG C and the atomization pressure to be 0.25 MPa to obtain the chitosan-acrylic acid copolymer.

[0031] The foaming agent comprises cement foaming agent and silicone foam stabilizer, and the weight ratio of the cement foaming agent to the silicone foam stabilizer is 1:0.3.

[0032] The preparation method of the mine fire extinguishing material comprises the following steps:

[0033] (1) One half of the weight of water is added to the mixture of the sulphoaluminate cement, the acid-activated coal gangue, the nano-silicon dioxide, the zinc borate and the expanded graphite, and stirring is performed at 750 rpm for 12 min to form a uniform slurry;

[0034] (2) The chitosan-acrylic acid copolymer is added, and the stirring speed is adjusted to 450 rpm and maintained for 8 min; the polypropylene fiber and the hollow glass microsphere are premixed and then added to the mixture, and stirring is performed at 550 rpm for 45 min; the bentonite-based composite phase change body is added, and low-speed stirring is performed at 350 rpm for 3 min;

[0035] (3) The cement foaming agent, the silicone foam stabilizer and the remaining water are added, and stirring is performed at 250 rpm for 18 min to obtain the mine fire extinguishing material.

[0036] Example 2

[0037] The mine fire prevention and extinguishing material provided in the embodiment is composed of the following raw materials in parts by weight: sulphate cement 30 parts, acid-activated coal gangue 20 parts, bentonite-based composite phase change body 5 parts, hollow glass microbeads 3 parts, polypropylene fiber 0.5 parts, chitosan-acrylic acid copolymer 3 parts, foaming agent 1 part, expanded graphite 2 parts, zinc borate 1 part, nano-silicon dioxide 2 parts, and water 260 parts;

[0038] The preparation method of the acid-activated coal gangue comprises the following steps: drying coal gangue at 100℃ for 2h, crushing the dried coal gangue to 200 mesh, mixing the crushed coal gangue with a 10% sulfuric acid solution at a solid-liquid ratio of 1g:3mL, stirring at a temperature of 80℃ and a speed of 180rpm for 2h, separating and washing by vacuum filtration, placing the acid-washed coal gangue in a muffle furnace, heating at a rate of 5℃ / min to 560℃, maintaining the temperature for 50min, naturally cooling to room temperature, and grinding to an average particle size of 40μm to obtain the acid-activated coal gangue;

[0039] The preparation method of the bentonite-based composite phase change body comprises the following steps: mixing bentonite, anhydrous sodium sulfate, and water, ultrasonic dispersing at a power of 500W and a frequency of 40kHz for 30min to form a uniform suspension, transferring the suspension to a constant-temperature reaction kettle, stirring at 60℃ and a speed of 400rpm for 3h, centrifuging at a speed of 8000rpm for 10min, vacuum drying the precipitate at 70℃ for 10h, and grinding and sieving the dried material through a 200-mesh sieve to obtain the bentonite-based composite phase change body; the weight ratio of bentonite, anhydrous sodium sulfate, and water is 3:1:20;

[0040] The preparation method of the chitosan-acrylic acid copolymer comprises the following steps: adding 50g of chitosan into 900mL of a 2% acetic acid solution, stirring at a speed of 500rpm for 20min, heating to 50℃ to accelerate dissolution to form a chitosan solution, adding 140g of acrylic acid monomer into the chitosan solution at a rate of 1mL / min, while adding 2g of potassium persulfate initiator, reacting at 200rpm and 60℃ for 3h under nitrogen protection, cooling to room temperature, and slowly adding a 10% NaOH solution to neutralize to adjust the pH to 7, and performing spray drying by controlling the air inlet temperature to 170℃, the air outlet temperature to 80℃, and the atomization pressure to 0.2MPa to obtain the chitosan-acrylic acid copolymer;

[0041] The foaming agent comprises cement foaming agent and silicone foam stabilizer at a weight ratio of 1:0.2;

[0042] The preparation method of the mine fire prevention and extinguishing material comprises the following steps:

[0043] (1) adding sulphate cement, acid-activated coal gangue, nano-silicon dioxide, zinc borate, and expanded graphite into half of the weight of water in sequence, stirring at a speed of 700rpm for 10min to form a uniform slurry;

[0044] (2) Add chitosan-acrylic acid copolymer, adjust the stirring speed to 400 rpm, and continue for 5 min; add polypropylene fibers and hollow glass microspheres after pre-mixing, stir at 500 rpm for 3 min; add bentonite-based composite phase change material, stir at 300 rpm for 2 min;

[0045] (3) Add cement foaming agent, silicone foam stabilizer, and the remaining water, stir at 200 rpm for 15 min, and then obtain.

[0046] Example 3

[0047] The fire extinguishing material for mine provided in this embodiment is composed of the following raw materials by weight: 40 parts of sulphoaluminate cement, 25 parts of acid-activated coal gangue, 10 parts of bentonite-based composite phase change material, 5 parts of hollow glass microspheres, 1 part of polypropylene fiber, 4 parts of chitosan-acrylic acid copolymer, 2 parts of foaming agent, 3 parts of expanded graphite, 3 parts of zinc borate, 4 parts of nano-silicon dioxide, and 320 parts of water;

[0048] The preparation method of the acid-activated coal gangue includes drying the coal gangue at 110°C for 3 h, crushing it to 200 mesh, mixing the crushed coal gangue with a 10% sulfuric acid solution at a solid-liquid ratio of 1 g:4 mL, stirring at a temperature of 80°C and a speed of 220 rpm for 3 h, separating and washing by vacuum filtration, placing the acid-washed coal gangue in a muffle furnace, heating it to 600°C at a rate of 5°C / min, maintaining the temperature for 70 min, naturally cooling it to room temperature, and grinding it to an average particle size of 40μm to obtain the acid-activated coal gangue;

[0049] The preparation method of the bentonite-based composite phase change material includes mixing bentonite, anhydrous sodium sulfate, and water, ultrasonic dispersing at a power of 500 W and a frequency of 40 kHz for 40 min to form a uniform suspension, transferring the suspension to a constant-temperature reaction kettle, stirring at 60°C and 500 rpm for 4 h, centrifuging at 8000 rpm for 10 min, vacuum drying the precipitate at 80°C for 12 h, and grinding and sieving the dried material through a 200-mesh sieve to obtain the bentonite-based composite phase change material; the weight ratio of bentonite, anhydrous sodium sulfate, and water is 4:2:30;

[0050] The preparation method of the chitosan-acrylic acid copolymer includes adding 60 g of chitosan into 1100 mL of a 3% acetic acid solution, stirring at 600 rpm for 30 min, accelerating the dissolution by heating to 55°C to form a chitosan solution, adding 160 g of acrylic acid monomer into the chitosan solution at a rate of 1 mL / min, adding 3 g of potassium persulfate initiator at the same time, reacting at 300 rpm and 60°C for 4 h under nitrogen protection, cooling to room temperature, and slowly adding a 10% NaOH solution to neutralize to adjust the pH to 7, and then performing spray drying by controlling the air inlet temperature to 180°C, the air outlet temperature to 90°C, and the atomization pressure to 0.3 MPa to obtain the chitosan-acrylic acid copolymer.

[0051] wherein the foaming agent comprises cement foaming agent and silicone foam stabilizer in a weight ratio of 1:0.5;

[0052] The preparation method of the mine fire extinguishing material comprises the following steps:

[0053] (1) Add sulphoaluminate cement, acid-activated coal gangue, nano-silicon dioxide, zinc borate and expanded graphite into half of the weight of water in sequence, stir at 800 rpm for 15 min to form a uniform slurry;

[0054] (2) Add chitosan-acrylic acid copolymer, adjust the stirring speed to 500 rpm and continue for 10 min; add polypropylene fiber and hollow glass microspheres after pre-mixing, stir at 600 rpm for 5 min; add bentonite-based composite phase change material, stir at 400 rpm for 4 min;

[0055] (3) Add cement foaming agent and silicone foam stabilizer, and the remaining water, stir at 300 rpm for 20 min, and then obtain.

[0056] Example 4

[0057] The mine fire extinguishing material provided in this embodiment is composed of the following weight parts of raw materials: sulphoaluminate cement 30 parts, acid-activated coal gangue 25 parts, bentonite-based composite phase change material 5 parts, hollow glass microspheres 5 parts, polypropylene fiber 0.5 parts, chitosan-acrylic acid copolymer 4 parts, foaming agent 1 part, expanded graphite 3 parts, zinc borate 1 part, nano-silicon dioxide 4 parts and water 260 parts;

[0058] The preparation method of the acid-activated coal gangue comprises the following steps: dry the coal gangue at 110°C for 2 h, crush it to 200 mesh, mix the crushed coal gangue with a 10% sulfuric acid solution with a solid-liquid ratio of 1 g:4 mL, stir at a temperature of 80°C and a speed of 220 rpm for 2 h, separate and wash by vacuum filtration, place the acid-washed coal gangue in a muffle furnace, heat it to 600°C at a rate of 5°C / min, keep the temperature constant for 50 min, naturally cool it to room temperature, grind it to an average particle size of 40 μm, and then obtain the acid-activated coal gangue;

[0059] The preparation method of the bentonite-based composite phase change material comprises the following steps: mix bentonite, anhydrous sodium sulfate and water, ultrasonically disperse them at a power of 500 W and a frequency of 40 kHz for 40 min to form a uniform suspension, transfer the suspension to a constant-temperature reaction kettle, stir at 60°C and 400 rpm for 4 h, centrifuge at 8000 rpm for 10 min, take the precipitate, vacuum dry it at 70°C for 12 h, grind and sieve it through a 200-mesh sieve after drying, and then obtain the bentonite-based composite phase change material; the weight ratio of bentonite, anhydrous sodium sulfate and water is 3:2:20;

[0060] The preparation method of the chitosan-acrylic acid copolymer comprises: adding 60 g of chitosan into 900 mL of 3% acetic acid solution, stirring at 500 rpm for 30 min, accelerating dissolution at 50°C to form a chitosan solution; adding 160 g of acrylic acid monomer into the chitosan solution at a speed of 1 mL / min, while adding 2 g of potassium persulfate initiator, reacting at 300 rpm and 60°C for 3 h under nitrogen protection, cooling to room temperature, and slowly adding a 10% NaOH solution to neutralize to adjust the pH to 7; and performing spray drying by controlling the air inlet temperature to be 180°C, the air outlet temperature to be 80°C, and the atomization pressure to be -0.3 MPa to obtain the chitosan-acrylic acid copolymer.

[0061] The foaming agent comprises cement foaming agent and silicone foam stabilizer in a weight ratio of 1:0.2.

[0062] The preparation method of the mine fire extinguishing material comprises the following steps:

[0063] (1) A half weight portion of water is sequentially added with sulphoaluminate cement, acid-activated coal gangue, nano-silicon dioxide, zinc borate and expanded graphite, and stirred at 700 rpm for 15 min to form a uniform slurry;

[0064] (2) The chitosan-acrylic acid copolymer is added, and the stirring speed is adjusted to 400 rpm for 10 min; the polypropylene fiber and the hollow glass microbeads are pre-mixed and added, and stirred at 500 rpm for 5 min; the bentonite-based composite phase change body is added, and stirred at 300 rpm for 4 min;

[0065] (3) The cement foaming agent, the silicone foam stabilizer and the remaining water are added, and stirred at 200 rpm for 20 min to obtain the product.

[0066] Comparative Example 1

[0067] In Comparative Example 1, the acid-activated coal gangue is replaced by unactivated coal gangue with an average particle size of 40 μm, and the rest is the same as in Example 1, and the preparation steps are the same as in Example 1.

[0068] Comparative Example 2

[0069] In Comparative Example 2, no acid-activated coal gangue is added, and the rest is the same as in Example 1, and the preparation steps are the same as in Example 1.

[0070] Comparative Example 3

[0071] In Comparative Example 3, the bentonite-based composite phase change body is replaced by bentonite with a particle size of 200 mesh, and the rest is the same as in Example 1, and the preparation steps are the same as in Example 1.

[0072] Comparative Example 4

[0073] Comparative Example 4 was prepared in the same manner as Example 1 except that bentonite-based composite phase change material was not added.

[0074] Comparative Example 5

[0075] Comparative Example 5 was prepared in the same manner as Example 1 except that the chitosan-acrylic acid copolymer was replaced by sodium alginate.

[0076] Comparative Example 6

[0077] Comparative Example 6 was prepared in the same manner as Example 1 except that the expanded graphite was replaced by zinc borate.

[0078] Test Example 1: The mine fire extinguishing and preventing materials prepared in the foregoing Examples 1-4 and Comparative Examples 1-6 were tested as follows:

[0079] Compressive strength: The materials were made into 100x100x20mm test blocks, and after curing for 7 days, the test was performed in accordance with GB / T 17671-2021 “Cement mortar strength test method”;

[0080] Resistance performance: The resistance rate at a coal temperature of 100°C was tested in accordance with MT / T 700-2019 “General technical conditions for fire retardant for coal mine fire prevention”;

[0081] High temperature dehydration and structural stability test: Referring to the crack resistance test method in GB / T 23439-2017 “Concrete expanding agent”, the materials were made into 100x100x20mm test blocks, and after curing for 7 days, the test blocks were placed in a 200°C constant temperature oven for 1 hour, and after cooling, the mass loss rate was measured, and the surface cracks were observed;

[0082] Storage stability test: Accelerated aging was performed in accordance with GB / T 50082-2009 “Test method for long-term performance and durability of ordinary concrete”;

[0083] (1) Wet-dry cycle: The test blocks were dried in a 50°C oven for 12 hours, then soaked in water for 12 hours, and after 10 cycles, the compressive strength retention rate was tested;

[0084] (2) High temperature and high humidity storage: The materials were sealed and stored in a 40°C, 90% humidity environment for 30 days, and the changes in slurry fluidity (slump) and foaming ratio were detected.

[0085] The results are shown in Table 1 below:

[0086] Table 1

[0087]

[0088] In combination with the foregoing, Example 1 has the best performance. The compressive strength and retardation rate of the unactivated coal gangue in Comparative Example 1 are significantly lower than those of Example 1, and the high-temperature mass loss rate increases by 65%. This is because the unactivated coal gangue has low surface activity, and cannot remove impurities by acid pickling and form a porous structure by calcination, resulting in weak interfacial bonding with the cement matrix and decreased retardation performance. The compressive strength and retardation rate of the acid-activated coal gangue in Comparative Example 2 are further reduced, and the crack density is the highest. This is because the acid-activated coal gangue has both cementitious activity and adsorption function, and its absence leads to a loose material skeleton and uneven dispersion of the retardation component, resulting in a significant deterioration in thermal stability. In Comparative Example 3, bentonite is replaced by the composite phase change body, and the high-temperature mass loss rate and crack density increase significantly, and the storage stability decreases. This is because ordinary bentonite lacks phase change energy storage capability, and cannot buffer temperature stress through phase change endothermic, resulting in material dehydration and cracking at high temperatures. In Comparative Example 4, there is no bentonite-based composite phase change body, and the compressive strength and retardation rate are the lowest, and the high-temperature mass loss rate is the highest. This is because the absence of the composite phase change body causes the material to lose thermal management capability, resulting in rapid evaporation of water and structural collapse, and weakening the synergistic enhancement effect of inorganic-organic components. In Comparative Example 5, sodium alginate replaces chitosan-acrylic acid copolymer, and the retardation rate is slightly lower than that of Example 1, and the high-temperature crack density increases. This is because the chitosan-acrylic acid copolymer has both film-forming and chelation functions, and its absence leads to a decrease in the release capability of the retardant and a decrease in the interfacial adhesion between the fiber and the matrix. In Comparative Example 6, zinc borate replaces expanded graphite, and the retardation rate decreases significantly, and the high-temperature mass loss rate is high. This is because the high-temperature expansion property of expanded graphite can form a dense heat insulation layer, while single zinc borate only provides chemical flame retardation and lacks physical barrier effect.

[0089] The above merely describes preferred embodiments of the present application and is not intended to limit the present application. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application shall be included in the protection scope of the present application.

Claims

1. A fire extinguishing and preventing material for a mine, characterized by comprising: a water-soluble polymer; and a water-soluble inorganic salt. It is composed of the following raw materials in parts by weight: 30-40 parts of sulfoaluminate cement, 20-25 parts of acid-activated coal gangue, 5-10 parts of bentonite-based composite phase variant, 3-5 parts of hollow glass microspheres, 0.5-1 part of polypropylene fiber, 3-4 parts of chitosan-acrylic acid copolymer, 1-2 parts of foaming agent, 2-3 parts of expanded graphite, 1-3 parts of zinc borate, 2-4 parts of nano silica, and 260-320 parts of water.

2. The fire extinguishing and preventing material for mine shaft according to claim 1, characterized in that, The method for preparing acid-activated coal gangue includes drying coal gangue at 100-110℃ for 2-3 hours, pulverizing it to 200 mesh, mixing the pulverized coal gangue with a 10% sulfuric acid solution at a solid-liquid ratio of 1g:3-4mL, stirring at 80±2℃ and 180-220rpm for 2-3 hours, separating and washing under vacuum, placing the acid-washed coal gangue in a muffle furnace, heating it to 560-600℃ at 5℃ / min, calcining it at a constant temperature for 50-70 minutes, naturally cooling it to room temperature, and grinding it to a particle size ≤50μm to obtain the final product.

3. The fire extinguishing and preventing material for mine according to claim 1, characterized in that, The preparation method of the bentonite-based composite phase change includes: mixing bentonite, anhydrous sodium sulfate and water; ultrasonically dispersing for 30-40 min to form a uniform suspension; transferring the suspension to a constant temperature reactor and stirring at 60℃±1℃ and 400-500 rpm for 3-4 h; centrifuging to separate the precipitate, vacuum drying at 70-80℃ for 10-12 h, and then grinding and passing the dried material through a 200-mesh sieve to obtain the final product.

4. The fire-fighting material for mines according to claim 3, wherein the weight ratio of bentonite, anhydrous sodium sulfate and water is 3-4:1-2:20-30.

5. The fire extinguishing and preventing material for mine according to claim 1, characterized in that, The preparation method of the chitosan-acrylic acid copolymer includes: adding chitosan to an acetic acid solution with a volume concentration of 2%-3%, stirring at 500-600 rpm for 20-30 min, heating to 50-55℃ to accelerate dissolution and form a chitosan solution; adding acrylic acid monomer dropwise to the chitosan solution at a rate of 1 mL / min, while adding potassium persulfate initiator to carry out the reaction, cooling to room temperature, and adjusting the pH to 7±0.2; and spray drying to obtain the final product.

6. The fire extinguishing and preventing material for mine according to claim 5, characterized in that, The ratio of chitosan, acetic acid solution, acrylic monomer and potassium persulfate is 50-60g: 900-1100mL: 140-160g: 2-3g.

7. The fire extinguishing and preventing material for mine according to claim 5, characterized in that, The reaction was carried out under nitrogen protection at 200-300 rpm and 60℃±1℃ for 3-4 hours.

8. The fire extinguishing and preventing material for mine according to claim 5, characterized in that, The spray dryer has an inlet air temperature of 170-180℃, an outlet air temperature of 80-90℃, and an atomization pressure of 0.2-0.3MPa.

9. The fire extinguishing and preventing material for mine according to claim 1, characterized in that, The foaming agent includes a cement foaming agent and a silicone resin foam stabilizer with a weight ratio of 1:0.2-0.

5.

10. A method for the preparation of a fire extinguishing and preventing material for mines according to any one of claims 1-9, characterized by the steps of include: (1) Add sulfoaluminate cement, acid-activated coal gangue, nano silica, zinc borate and expanded graphite to half the weight of water in sequence, and stir at 700-800 rpm for 10-15 min to form a uniform slurry. (2) add chitosan-acrylic acid copolymer, adjust the stirring speed to 400-500 rpm, and continue for 5-10 min; add the polypropylene fiber and hollow glass microspheres after pre-mixing, and stir at 500-600 rpm for 3-5 min; add the bentonite-based composite phase change body, and stir at 300-400 rpm for 2-4 min at low speed; (3) add the foaming agent and the remaining weight parts of water, and stir at 200-300 rpm for 15-20 min to obtain the product.

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