Coal-based solid waste-based fire prevention and extinguishing material with carbon dioxide self-adsorption and desorption function and application thereof

Abstract

The application discloses a coal-based solid waste-based fire prevention and extinguishing material with carbon dioxide self-adsorption and desorption functions and application thereof. The fire prevention and extinguishing material is prepared by reacting coal gangue and / or low-calcium fly ash coal-based solid waste ground in carbon dioxide, an additive and an activator composed of sodium pyrophosphate, sodium carbonate and sodium methylsilanol in an aqueous solution with a pH of 9-12 at normal temperature and pressure. The fire prevention and extinguishing material is injected into a downhole goaf through a grouting pipeline to block air leakage cracks, and a large amount of carbon dioxide is absorbed and stored in a high-humidity environment. When a fire occurs in the downhole, the adsorbed carbon dioxide is desorbed and released to achieve fire extinguishing, and the adsorbed fire prevention and extinguishing material is regenerated to re-adsorb carbon dioxide in a high-humidity environment. The fire prevention and extinguishing material realizes resourceful disposal of coal-based solid waste, can adsorb and store carbon dioxide, and can self-desorb and store carbon dioxide to achieve fire extinguishing after a fire occurs, thereby improving the efficiency of downhole fire prevention and extinguishing, and having the advantages of mild reaction conditions and green environmental protection.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of coal mine fire prevention and extinguishing, and particularly relates to a coal-based solid waste-based fire prevention and extinguishing material with carbon dioxide self-adsorption and desorption functions and application thereof. BACKGROUND

[0002] Coal spontaneous combustion fire is one of the important disasters that seriously threaten the safety production of coal mines. Coal seams in China have diversified geological characteristics, and the mining of spontaneous combustion coal seams is widely distributed in mining areas, and coal fire accidents are serious. Coal spontaneous combustion is the result of physical and chemical changes of coal with spontaneous combustion tendency under the conditions of suitable oxygen supply, oxidizing heat accumulation environment and time. Air leakage in coal mines is the key reason for coal spontaneous combustion disasters, therefore, effective plugging of air leakage channels is the key to preventing coal spontaneous combustion.

[0003] At present, cement-based inorganic plugging materials are mainly used to plug air leakage to prevent coal spontaneous combustion in domestic coal mines. However, the high energy consumption and high carbon emission in the production process of cement have brought great pressure on environmental protection and effective use of resources in China, which cannot meet the strategic development demand of "carbon peak and carbon neutralization". At the same time, a large amount of solid waste such as coal gangue and fly ash is produced in the development and utilization process of coal, and the accumulation of solid waste not only occupies land but also pollutes the environment, so it is urgent to realize the resource-efficient utilization of coal-based solid waste. At present, one of the main ways to realize the resource-efficient utilization of coal-based solid waste is to use alkali to activate solid waste to form cementitious plugging materials or add fly ash in cement to reduce the cement usage of plugging materials. However, the composition and activity of solid waste are unstable, which brings difficulties to the formation and application of such cementitious materials. Adding fly ash in cement also cannot completely replace cement, which cannot meet the demand of carbon dioxide emission reduction.

[0004] To better promote the resource utilization of solid waste, reduce carbon emissions, and solve the problem of coal spontaneous combustion prevention, carbon dioxide is introduced into solid waste to mineralize and modify the solid waste-based mine fire prevention and extinguishing material. CN117138296A discloses a method for preparing a fire prevention and extinguishing material using solid waste, mixing fly ash, carbide slag, coal gangue, and desulfurization gypsum with water, and introducing carbon dioxide for mineralization reaction to obtain a mineralized slurry with significantly reduced fluidity, which is covered on the coal seam prone to spontaneous combustion to achieve the purpose of fire extinguishing. CN115337588A discloses a fly ash-based fire prevention and extinguishing material for mineralizing and sealing carbon dioxide, which introduces carbon dioxide into a slurry containing fly ash, solid strong base, and water at room temperature, maintains a pressure of 1-3 bar, and stirs at high speed for 3-5 minutes, then increases the carbon dioxide pressure to 10 bar or above, stirs at low speed for 10-15 minutes to obtain a fly ash-based fire prevention and extinguishing material for mineralizing and sealing carbon dioxide, which is transported to the goaf through a grouting pipeline and applied to prevent and control coal spontaneous combustion in the goaf. CN116332613A also discloses a fully solid waste tough material for carbon sequestration and sealing underground fractures and a preparation method thereof, which uses desulfurization gypsum, fly ash, carbide slag, steel scrap, and other cementitious components, and waste rubber particles, steel slag, and coal gangue powder, and other toughening components to react with carbon dioxide at room temperature and atmospheric pressure to obtain a tough material for sealing underground air leakage fractures. However, these methods all achieve mineralization and sealing of carbon dioxide by solidifying it into calcium carbonate, although CN109970413A discloses that the filler calcium carbonate can decompose into calcium oxide and carbon dioxide when heated, and the released carbon dioxide can block oxygen, thereby playing a fireproofing role. However, the patent also discloses that calcium carbonate needs to be heated to a temperature of 825 ℃ to release carbon dioxide, which is obviously impossible in a coal mine underground, which also indicates that calcium carbonate is a stable compound. Therefore, the above patents related to solid waste-based carbon sequestration and fire prevention methods all involve permanent carbon dioxide mineralization, and the mineralized material can only prevent and control coal spontaneous combustion by isolating coal from oxygen or sealing air leakage fractures. Carbon dioxide can not only extinguish open fires, but also extinguish hidden high-temperature fire areas, and more importantly, it can penetrate into the gaps between coal seams and adsorb onto the surface of coal bodies to prevent coal from contacting oxygen, thereby effectively preventing the rekindling of fire areas. The mineralized carbon dioxide in the methods disclosed in the above patents based on solid waste for carbon sequestration and fire prevention cannot exhibit its inert gas fire prevention and extinguishing properties. SUMMARY

[0005] The present application aims to provide a coal-based solid waste-based fire prevention and extinguishing material with carbon dioxide self-adsorption and desorption functions and an application thereof, the material taking fly ash and / or coal gangue coal-based solid waste as main raw materials, being obtained through reaction at normal temperature and pressure in a high-humidity environment in a coal mine, and integrating plugging air leakage and carbon dioxide self-adsorption and desorption functions, so as to effectively capture carbon dioxide to plug air leakage cracks in a coal mine under normal temperature and pressure conditions, and automatically release the adsorbed carbon dioxide to extinguish fire when a fire temperature rise is detected. The coal-based solid waste-based fire prevention and extinguishing material is suitable for industrial production, realizes resource disposal of coal-based solid waste, and achieves the purposes of carbon dioxide emission reduction, storage and efficient utilization, improves the efficiency of fire prevention and extinguishing in a coal mine, and has the advantages of green environmental protection.

[0006] To solve the problems in the prior art, the technical scheme adopted by the present application is as follows:

[0007] A coal-based solid waste-based fire prevention and extinguishing material with carbon dioxide self-adsorption and desorption functions is prepared by reacting coal-based solid waste, an additive and an activator composed of sodium pyrophosphate, sodium carbonate and sodium methylsilanolate in an aqueous solution with a pH of 9-12 at normal temperature and pressure, wherein the coal-based solid waste includes low-calcium fly ash and / or coal gangue, and the weight ratio of the low-calcium fly ash to the coal gangue is 0:10-10:0; the sodium pyrophosphate accounts for 2-4% of the total weight of the coal-based solid waste; the sodium carbonate accounts for 2-5% of the total weight of the coal-based solid waste; the sodium methylsilanolate accounts for 2-4% of the total weight of the coal-based solid waste; the additive is mixed by hydroxyl sodalite, sodium alunite, sodium-based activated clay and tetraethyl orthosilicate at a weight ratio of 25-30:20-28:30-35:5-8, and accounts for 5-10% of the total weight of the coal-based solid waste; and the weight ratio of the coal-based solid waste to water is 0.4-0.5:1.

[0008] Further, the coal-based solid waste is sieved through a 200-mesh sieve after dry grinding for 60-90 min in a carbon dioxide atmosphere until the proportion of the weight of the undersize to the total weight of the ground material is greater than or equal to 95%.

[0009] Further, the coal gangue is uncalcined coal gangue, and the low-calcium fly ash is F-grade low-calcium fly ash, i.e., the CaO content is less than 10 wt.%.

[0010] Further, the initial temperature for self-desorption of carbon dioxide of the fire prevention and extinguishing material after adsorbing carbon dioxide is 120-125 DEG C, and the rate of releasing carbon dioxide gradually increases with the temperature rise.

[0011] The above-mentioned coal-based solid waste-based fire prevention and extinguishing material with carbon dioxide self-adsorption and desorption functions has a specific preparation method including the following steps:

[0012] Step 1, preparation of the additive and the activator;

[0013] Step 2, the low-calcium fly ash and / or coal gangue ball-milled and sieved under a carbon dioxide atmosphere are mixed with water in a proportion, an activator is added, the pH value of the solution is adjusted to 9-12, an additive is added to the obtained mixture, and a slurry of the fire extinguishing and preventing material with the function of carbon dioxide self-adsorption and desorption is obtained after stirring for 5-10 min.

[0014] The coal-based solid waste-based fire extinguishing and preventing material is recycled in the absorption and desorption of carbon dioxide, is transported to a goaf in a coal mine through a grouting pipeline, carbon dioxide is injected into the fire extinguishing and preventing material through a gas pipeline, and the carbon dioxide is absorbed in a high-humidity environment in the coal mine; when a fire occurs in the coal mine and the environmental temperature rises to 120-125 DEG C, the coal-based solid waste-based fire extinguishing and preventing material desorbs and releases carbon dioxide to extinguish the fire, and the coal-based solid waste-based fire extinguishing and preventing material after releasing the carbon dioxide absorbs the carbon dioxide in the coal mine in the high-humidity environment in the coal mine, so that the recycling is realized. Advantages

[0015] Compared with the prior art, the coal-based solid waste-based fire extinguishing and preventing material with the function of carbon dioxide self-adsorption and desorption and the application thereof have the following advantages.

[0016] 1. The coal-based solid waste-based fire extinguishing and preventing material with the function of carbon dioxide self-adsorption and desorption is prepared from coal-based solid waste as a main raw material under normal temperature and pressure, is injected into a goaf in a coal mine, realizes the resource disposal of the coal-based solid waste, blocks air leakage cracks, captures carbon dioxide, desorbs the carbon dioxide to extinguish a fire when the temperature in the coal mine rises to a certain temperature, and can absorb the carbon dioxide again in a high-humidity environment in the coal mine, so that the recycling is realized.

[0017] 2. The coal-based solid waste used in the application is ground and crushed under a carbon dioxide atmosphere, and the carbon dioxide adsorption capacity of the solid waste is increased through ball milling.

[0018] 3. The present application uses sodium pyrophosphate, sodium carbonate and sodium methylsilanol as active agents, on the one hand, avoiding the negative impact on the environment caused by the use of strong alkali NaOH; on the other hand, the alkalinity of sodium pyrophosphate, sodium carbonate and sodium methylsilanol is lower than that of NaOH, and by adjusting the amount of addition, the pH of the reaction system is adjusted to 9-12, under this pH condition, even if there are calcium ions in the reaction system, they cannot replace the sodium ions in the matrix, and the conversion of aluminum silicate sodium (N-A-S-H) into aluminum calcium silicate (C-A-S-H) can be avoided, so that the matrix system is mainly N-A-S-H, and after the carbon dioxide is introduced, the carbon dioxide reacts with N-A-S-H to generate sodium carbonate, which can avoid the generation of permanent mineralization product calcium carbonate; in the presence of excess carbon dioxide and high humidity in the well, sodium carbonate is further converted into sodium bicarbonate; when the temperature rises to 120-125 DEG C due to fire, sodium bicarbonate decomposes to release carbon dioxide, realizing the self-adsorption and desorption of carbon dioxide. The released carbon dioxide dilutes the oxygen concentration in the air, and plays a role of inert gas fire extinguishing, further improving the fire extinguishing efficiency.

[0019] 4. The present application uses hydroxyl sodalite, sodium alunite, sodium-based activated clay and tetraethyl orthosilicate as additives, on the one hand, the composition of hydroxyl sodalite is Na8Al6Si6O 24 ·(OH)2, which has a similar structure to zeolite; and the sodium-based activated clay has a layered structure, the addition of hydroxyl sodalite and sodium-based activated clay in the gel system of aluminosilicate can increase its carbon dioxide absorption capacity; on the other hand, the addition of hydroxyl sodalite and sodium alunite in the reaction system can increase the content of Na2O therein, promote the generation of N-A-S-H, and inhibit the ion exchange of N-A-S-H by Ca 2+ ions; at the same time, tetraethyl orthosilicate can provide a silicon source, and alleviate the side reactions caused by the insufficient dissolution of active SiO2 in coal-based solid waste. BRIEF DESCRIPTION OF DRAWINGS

[0020] Figure 1 The cyclic adsorption of the coal-based solid waste-based fire prevention and extinguishing material prepared in different embodiments of the present application. DETAILED DESCRIPTION

[0021] The present application will be further described below in conjunction with the drawings and specific embodiments in the embodiments of the present application. Obviously, the described embodiments are only a part of the embodiments of the present application, and are not all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor fall within the protection scope of the present application. Example 1

[0022] A coal-based solid waste-based fire prevention and extinguishing material with carbon dioxide self-adsorption and desorption function is prepared from the following raw materials in parts by weight: 100 parts of coal gangue milled under carbon dioxide atmosphere, 40 parts of water, 2 parts of sodium pyrophosphate, 2 parts of sodium carbonate, 2 parts of sodium methylsilanol, and 6 parts of an additive composed of hydroxyl sodalite, sodium alunite, sodium-based activated clay, and tetraethyl orthosilicate in a composition ratio of 30:25:35:5.

[0023] First, the preparation of the fire prevention and extinguishing material with carbon dioxide self-adsorption and desorption function: the coal gangue milled under carbon dioxide atmosphere is added to water in proportion, stirred at room temperature for 1-3 min, and then an activator composed of sodium pyrophosphate, sodium carbonate, and sodium methylsilanol is added, and the pH value is adjusted to 9-12 to obtain a uniform slurry; then the additive is added to the above mixed slurry, stirred at room temperature for 5-10 min, and a slurry of the carbon fixation coal-based solid waste-based fire prevention and extinguishing material is obtained.

[0024] Second, carbon absorption grouting: the obtained slurry of the carbon fixation coal-based solid waste-based fire prevention and extinguishing material is added to a ground grouting system, transported to the underground goaf through a grouting pipeline, and then carbon dioxide is continuously introduced into the interior of the fire prevention and extinguishing material slurry through a gas pipeline; when the flow rate of the carbon dioxide remains unchanged and the injection pressure increases, the introduction of carbon dioxide is stopped after 3 hours of continuous introduction. Example 2

[0025] A coal-based solid waste-based fire prevention and extinguishing material with carbon dioxide self-adsorption and desorption function is prepared from the following raw materials in parts by weight: 100 parts of coal gangue milled under carbon dioxide atmosphere, 40 parts of water, 2 parts of sodium pyrophosphate, 2 parts of sodium carbonate, 2 parts of sodium methylsilanol, and 6 parts of an additive composed of hydroxyl sodalite, sodium alunite, sodium-based activated clay, and tetraethyl orthosilicate in a composition ratio of 30:25:35:5.

[0026] The preparation method of the slurry of the coal-based solid waste-based fire prevention and extinguishing material with carbon dioxide self-adsorption and desorption function and the carbon absorption grouting method in this example are the same as those in Example 1. Example

[0027] A coal-based solid waste-based fire prevention and extinguishing material with carbon dioxide self-adsorption and desorption function is prepared from the following raw materials in parts by weight: 100 parts of coal gangue milled under carbon dioxide atmosphere, 40 parts of water, 2 parts of sodium pyrophosphate, 2 parts of sodium carbonate, 2 parts of sodium methylsilanol, and 6 parts of an additive composed of hydroxyl sodalite, sodium alunite, sodium-based activated clay, and tetraethyl orthosilicate in a composition ratio of 30:25:35:5.

[0028] The preparation method of the slurry of the coal-based solid waste-based fire prevention and extinguishing material with carbon dioxide self-adsorption and desorption function and the carbon absorption grouting method in this example are the same as those in Example 1. Example 4

[0029] A coal-based solid waste-based fire prevention and extinguishing material with carbon dioxide self-adsorption and desorption function is prepared from the following raw materials in parts by weight: 70 parts of coal gangue milled under a carbon dioxide atmosphere, 30 parts of low-calcium fly ash, 50 parts of water, 2 parts of sodium pyrophosphate, 4 parts of sodium carbonate, 2 parts of sodium methylsilanol, and 6 parts of an additive composed of hydroxyl sodalite, sodium alunite, sodium-based activated clay, and tetraethyl orthosilicate in a composition ratio of 30:25:35:5.

[0030] The preparation method of the slurry of the coal-based solid waste-based fire prevention and extinguishing material with carbon dioxide self-adsorption and desorption function and the carbon absorption grouting method in this embodiment are the same as those in Embodiment 1. Embodiment 5

[0031] A coal-based solid waste-based fire prevention and extinguishing material with carbon dioxide self-adsorption and desorption function is prepared from the following raw materials in parts by weight: 60 parts of coal gangue milled under a carbon dioxide atmosphere, 40 parts of low-calcium fly ash, 50 parts of water, 2 parts of sodium pyrophosphate, 4 parts of sodium carbonate, 2 parts of sodium methylsilanol, and 6 parts of an additive composed of hydroxyl sodalite, sodium alunite, sodium-based activated clay, and tetraethyl orthosilicate in a composition ratio of 30:25:35:5.

[0032] The preparation method of the slurry of the coal-based solid waste-based fire prevention and extinguishing material with carbon dioxide self-adsorption and desorption function and the carbon absorption grouting method in this embodiment are the same as those in Embodiment 1. Embodiment 6

[0033] A coal-based solid waste-based fire prevention and extinguishing material with carbon dioxide self-adsorption and desorption function is prepared from the following raw materials in parts by weight: 50 parts of coal gangue milled under a carbon dioxide atmosphere, 50 parts of low-calcium fly ash, 50 parts of water, 2 parts of sodium pyrophosphate, 4 parts of sodium carbonate, 2 parts of sodium methylsilanol, and 6 parts of an additive composed of hydroxyl sodalite, sodium alunite, sodium-based activated clay, and tetraethyl orthosilicate in a composition ratio of 30:25:35:5.

[0034] The preparation method of the slurry of the coal-based solid waste-based fire prevention and extinguishing material with carbon dioxide self-adsorption and desorption function and the carbon absorption grouting method in this embodiment are the same as those in Embodiment 1.

[0035] The CO2 adsorption and desorption performance of the coal-based solid waste-based fire prevention and extinguishing materials prepared in Embodiments 1-6 under normal pressure is evaluated by using a simultaneous thermal analyzer, and the specific data are shown in Table 1.

[0036] Table 1. CO2 adsorption and desorption amount of the coal-based solid waste-based fire prevention and extinguishing materials prepared in Embodiments 1-6

[0037]

[0038] The coal-based solid waste-based fire prevention and extinguishing material prepared in Examples 1-6 was subjected to a cyclic adsorption test by using a thermogravimetric analyzer to evaluate its cyclic property, and the specific results are shown in the following table. Figure 1 As can be seen from the results, the second CO2 adsorption amount of the coal-based solid waste-based fire prevention and extinguishing material is slightly lower than the first one, and then tends to be stable, which is because the coal-based solid waste still contains a small amount of calcium oxide, so a small amount of stable calcium carbonate is formed during the first CO2 adsorption. During the regeneration of the material, the calcium carbonate cannot be regenerated, resulting in a decrease in the regeneration amount and the re-adsorption amount. However, the subsequent cyclic adsorption property changes little, and the material still has a high adsorption amount after 5 repeated adsorptions.

Claims

1. A coal-based solid waste-based fire prevention and extinguishing material with carbon dioxide self-adsorption and desorption function, characterized in that, The coal-based solid waste, the additive and the activator composed of sodium pyrophosphate, sodium carbonate and sodium methylsilanolate are reacted in an aqueous solution with a pH of 9-12 at room temperature and normal pressure to prepare the coal-based solid waste-based fire prevention and extinguishing material, wherein the coal-based solid waste includes low-calcium fly ash and / or coal gangue, and the weight ratio of the low-calcium fly ash to the coal gangue is 0:10-10:0; the sodium pyrophosphate accounts for 2-4% of the total weight of the coal-based solid waste; the sodium carbonate accounts for 2-5% of the total weight of the coal-based solid waste; the sodium methylsilanolate accounts for 2-4% of the total weight of the coal-based solid waste; the additive is mixed by hydroxyl sodalite, sodium alunite, sodium-based activated clay and tetraethyl orthosilicate at a weight ratio of 25-30:20-28:30-35:5-8, and the amount is 5-10% of the total weight of the coal-based solid waste; and the weight ratio of the coal-based solid waste to water is 0.4-0.5:

1.

2. The coal-based solid waste-based fire prevention and extinguishing material with carbon dioxide self-adsorption and desorption function according to claim 1, characterized in that, The coal-based solid waste is sieved through a 200-mesh screen after dry grinding for 60-90 min under a carbon dioxide atmosphere until the proportion of the weight of the undersize to the total weight of the ground material is ≥95%.

3. The coal-based solid waste-based fire prevention and extinguishing material with carbon dioxide self-adsorption and desorption function according to claim 1, characterized in that, The coal gangue is uncalcined coal gangue, and the low-calcium fly ash is F-grade low-calcium fly ash, i.e., the CaO content is less than 10 wt.%.

4. The coal-based solid waste-based fire prevention and extinguishing material with carbon dioxide self-adsorption and desorption function according to claim 1, characterized in that, After the fire prevention and extinguishing material adsorbs carbon dioxide, the initial temperature for self-desorption of carbon dioxide is 120-125 ℃, and the rate of release of carbon dioxide gradually increases with the increase of temperature.

5. The method for preparing a coal-based solid waste-based fire prevention and extinguishing material with carbon dioxide self-adsorption and desorption function according to claim 1, characterized in that, The method comprises the following steps: Step 1, preparation of the additive and the activator; Step 2, the low-calcium fly ash and / or coal gangue sieved after ball milling under a carbon dioxide atmosphere are mixed with water in a proportion, the activator is added, the pH of the solution is adjusted to 9-12, the additive is added to the obtained mixture, and the slurry of the fire prevention and extinguishing material with the function of carbon dioxide self-adsorption and desorption is obtained after stirring and reaction for 5-10 min.

6. The cyclic utilization of coal-based solid waste-based fire prevention and extinguishing material in the absorption of carbon dioxide and desorption of carbon dioxide release according to any one of claims 1-5, characterized in that, The coal-based solid waste-based fire prevention and extinguishing material is delivered to a goaf in a coal mine through a grouting pipeline, carbon dioxide is injected into the fire prevention and extinguishing material through a gas pipeline, and the carbon dioxide is absorbed in a high-humidity environment in the coal mine; when a fire occurs in the coal mine, the temperature of the environment increases to 120-125 ℃, the coal-based solid waste-based fire prevention and extinguishing material desorbs and releases carbon dioxide to extinguish the fire, and the coal-based solid waste-based fire prevention and extinguishing material after the release of carbon dioxide absorbs carbon dioxide in the coal mine in a high-humidity environment, realizing cyclic utilization.

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