An oxygen-absorbing coal gangue porous material for preventing and treating combustion of goaf and a preparation method thereof

Abstract

This invention discloses an oxygen-absorbing porous coal gangue material for preventing coal combustion in goaf areas and its preparation method. The method involves first fabricating a porous material from coal gangue using a template method, and then imbuing the porous material with oxygen-absorbing capabilities through doping modification, thus obtaining the oxygen-absorbing porous coal gangue material. This invention primarily transforms coal mine solid waste into a high-value fire-fighting material, achieving effective utilization of solid waste. Solid waste is widely available, inexpensive, and the manufacturing method is simple. The resulting porous material, injected into the goaf along with slurry, forms an inertized isolation zone. Simultaneously, it absorbs existing oxygen in the goaf, creating a completely oxygen-free asphyxiation zone, inhibiting spontaneous coal combustion. Furthermore, the high strength of the porous material allows for vertical deposition of the slurry, preventing slurry collapse and completely sealing high-level fissures, demonstrating broad application prospects in mine fire prevention.

Description

Technical Field

[0001] This invention relates to the field of coal mine fire prevention and extinguishing technology, specifically to an oxygen-absorbing porous coal gangue material for preventing combustion in goaf areas and its preparation method. Background Technology

[0002] Spontaneous combustion of coal has always been a major hazard in coal mining, especially in goaf areas. After the roof collapses, complex fissures form, leading to severe air leakage and causing spontaneous combustion of residual coal, potentially triggering gas and dust explosions. Therefore, sealing is a fundamental measure for preventing spontaneous combustion. Commonly used sealing materials include mud, cement slurry, concrete, and polyurethane. However, mud slurry is highly fluid during injection, making precise sealing at high levels difficult. Furthermore, after water evaporates, the mud slurry shrinks and deforms, reforming air leakage channels and easily causing the residual coal to reignite. While polyurethane has superior performance, it suffers from high cost, high heat release during the reaction process, and limited performance characteristics.

[0003] Coal gangue is a byproduct of coal production and washing, and is a type of industrial waste. Currently, the total amount of coal gangue stockpiled in my country exceeds 7 billion tons, and this figure continues to grow annually. The primary application of coal gangue in coal mines is underground filling. For example, patent CN118084448A discloses a high-concentration coal gangue filling slurry and its preparation method; this slurry is easy to solidify, does not bleed water, and is convenient for pipeline transportation. Patent CN118255565A discloses a mine water solidification filling material containing CSH gel; the gel adsorbs anions and cations from the mine water and solidifies on the surface of coal gangue aggregate particles or fills particle gaps, then seals it in the goaf of the coal mine. However, there are currently no literature reports on using coal gangue to produce oxygen-absorbing fire-fighting materials. Summary of the Invention

[0004] The purpose of this invention is to provide an oxygen-absorbing porous coal gangue material for preventing combustion in goaf areas and its preparation method. The raw material used in this method, coal gangue, is widely available and inexpensive, and the manufacturing process is simple and easy to implement. The prepared porous material can effectively seal goaf areas and remove oxygen from enclosed spaces, forming an oxygen-free suffocation space to prevent spontaneous combustion of coal.

[0005] To achieve the above objectives, the present invention is implemented through the following technical solution:

[0006] A method for preparing an oxygen-absorbing porous coal gangue material for preventing combustion in goaf areas includes the following steps:

[0007] S1. Preparation of porous coal gangue materials;

[0008] S1-1. Add coal gangue powder pulverized to a finer mesh (greater than 200 mesh) to an excess of dilute hydrochloric acid, stir thoroughly and evenly for 10-15 minutes, and then filter to obtain acid-washed coal gangue.

[0009] S1-2. Mix pickled coal gangue with distilled water in a certain proportion and stir evenly for 15-20 minutes to obtain a 5-10 wt% coal gangue suspension.

[0010] S1-3. Add 1.5-5wt% of dispersant to the coal gangue suspension and stir evenly for 5-10 minutes under water bath heating at 50-60℃ to obtain coal gangue sol.

[0011] S1-4. Mix the template agent with distilled water in a certain proportion and stir evenly for 10-15 minutes to obtain a 10-20 wt% template agent suspension.

[0012] S1-5. The template agent suspension prepared in step S1-4 is added dropwise to the coal gangue sol prepared in step S1-3 at a mass ratio of 1:(5-10). The mixture is stirred evenly for 60-90 minutes under a water bath heating temperature of 40-60℃ to obtain a porous material precursor.

[0013] S1-6. Soak the porous material precursor in an organic solvent, stir evenly for 10-30 minutes, filter, and wash the filtered sample with distilled water 3-5 times to obtain the porous coal gangue material.

[0014] S2. Mix a certain proportion of adsorbent with distilled water and stir evenly for 3-10 minutes to obtain a 20-40 wt% adsorption solution.

[0015] S3. Mix the porous coal gangue material prepared in step S1 with the adsorption liquid prepared in step S2, and slowly add ammonia water while stirring continuously and evenly to control the pH of the solution to 8-10 to obtain a precipitate.

[0016] S4. Wash the precipitate with deionized water 3-5 times, and heat treat it at 400-600℃ for 120-150 minutes to obtain oxygen-absorbing porous coal gangue material.

[0017] Preferably, in step S1-1, the concentration of the dilute hydrochloric acid is 1-2M.

[0018] Preferably, in steps S1-3, the dispersant is polyvinylpyrrolidone.

[0019] Preferably, in steps S1-4, the template agent is one of polyacrylic acid microspheres, polymethyl methacrylate microspheres, or polystyrene microspheres.

[0020] Preferably, in steps S1-5, the titration rate of the template agent suspension is 2 s / drop.

[0021] Preferably, in steps S1-6, the organic solvent is one of dichloromethane, toluene, and tetrahydrofuran.

[0022] Preferably, in step S2, the adsorbent is one of cobalt nitrate, nickel nitrate, and cerium nitrate.

[0023] Preferably, in step S3, the concentration of ammonia is 1-2M.

[0024] Preferably, all stirring is done using magnetic stirring at a speed of 500-1000 rpm.

[0025] To achieve the above-mentioned objectives, the present invention also provides an oxygen-absorbing porous coal gangue material for preventing combustion in goaf areas prepared by the above-mentioned preparation method.

[0026] In the preparation process of this invention, impurities in coal gangue are first removed by acid washing, thereby enhancing its reactivity. Then, the dispersibility and stability of the material are improved by preparing a coal gangue suspension and adding dispersants. Simultaneously, the introduction of a template agent and the control of temperature and time form a precursor for the porous material, optimizing its pore structure and providing abundant adhesion sites for oxygen adsorption. The porous material prepared by this invention can effectively remove oxygen from the sealed space, creating an anaerobic asphyxiating environment and inhibiting spontaneous combustion of coal.

[0027] Compared with the prior art, the present invention has the following advantages:

[0028] (1) This invention uses coal gangue as a porous material and at the same time, it is given oxygen absorption function by doping modification. The prepared oxygen-absorbing coal gangue porous material can effectively block the air leakage channel in the goaf and absorb the oxygen present in the goaf, so that the closed space forms a completely oxygen-free isolation space and inhibits the spontaneous combustion of coal.

[0029] (2) The oxygen-absorbing porous coal gangue material prepared by the present invention achieves longitudinal accumulation of grout during the grouting process, thereby sealing high-level fracture channels.

[0030] (3) The raw material used in this invention, coal gangue, is widely available and inexpensive. The manufacturing process is simple and easy to implement. It also achieves effective treatment of solid waste and has good application prospects. The porous material made can be used efficiently for the prevention and control of spontaneous combustion in coal mine goaf areas. Attached Figure Description

[0031] Figure 1 These are adsorption isotherm diagrams for four embodiments of the present invention. Detailed Implementation

[0032] The present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0033] Example 1

[0034] A method for preparing an oxygen-absorbing porous coal gangue material for preventing combustion in goaf areas includes the following steps:

[0035] S1. Preparation of porous coal gangue materials:

[0036] S1-1. Crush 10g of coal gangue into powder of 200 mesh or higher and add it to an excess of 1M dilute hydrochloric acid. Stir evenly for 10 minutes and then filter to obtain acid-washed coal gangue.

[0037] S1-2. Mix 5g of pickled coal gangue with 45g of distilled water and stir evenly for 15min to obtain a coal gangue suspension.

[0038] S1-3. Add 1g of polyvinylpyrrolidone to the coal gangue suspension and stir evenly for 10min under 50℃ water bath heating to obtain coal gangue sol.

[0039] S1-4. Mix 10g of polyacrylic acid microspheres with 90g of distilled water and stir evenly for 10min to obtain a template agent suspension.

[0040] S1-5. Add 50g of template agent suspension to the coal gangue sol dropwise at a dropping rate of 2s / drop, and stir evenly for 60min under a water bath heating at 40℃ to obtain a porous material precursor.

[0041] S1-6. Soak the porous material precursor in dichloromethane and stir evenly for 10 minutes. Wash the filtered sample with distilled water 5 times to obtain the porous coal gangue material.

[0042] S2. Mix 10g of cobalt nitrate with 40g of distilled water and stir evenly for 3 minutes to obtain an adsorption solution.

[0043] S3. Mix the porous coal gangue material with the adsorption liquid, stir continuously and evenly, and slowly add 1M ammonia water to control the pH of the solution to 8 to obtain the precipitate.

[0044] S4. Wash the precipitate five times with deionized water and heat-treat it at 400℃ for 120 minutes to obtain oxygen-absorbing porous coal gangue material.

[0045] Example 2

[0046] A method for preparing an oxygen-absorbing porous coal gangue material for preventing combustion in goaf areas includes the following steps:

[0047] S1. Preparation of porous coal gangue materials:

[0048] S1-1. Crush 10g of coal gangue into powder of 200 mesh or higher and add it to excess 1M dilute hydrochloric acid. Stir evenly for 10 minutes and then filter to obtain acid-washed coal gangue.

[0049] S1-2. Mix 5g of pickled coal gangue with 55g of distilled water in a certain proportion and stir evenly for 20 minutes to obtain a coal gangue suspension.

[0050] S1-3. Add 1.5g of polyvinylpyrrolidone to the coal gangue suspension and stir evenly for 5min under water bath heating at 55℃ to obtain coal gangue sol.

[0051] S1-4. Mix 10g of polymethyl methacrylate microspheres with 80g of distilled water and stir evenly for 10min to obtain a template agent suspension.

[0052] S1-5. Add 20g of template agent suspension to the coal gangue sol dropwise at a dropping rate of 2s / drop, and stir evenly for 80min under a water bath heating at 50℃ to obtain a porous material precursor.

[0053] S1-6. Soak the porous material precursor in toluene and stir evenly for 10 minutes. Wash the filtered sample with distilled water 5 times to obtain the porous coal gangue material.

[0054] S2. Mix 10g of nickel nitrate with 20g of distilled water and stir evenly for 5 minutes to obtain the adsorption solution.

[0055] S3. Mix the porous coal gangue material with the adsorption liquid, stir continuously and evenly, and slowly add 2M ammonia water to control the pH of the solution to 10 to obtain the precipitate.

[0056] S4. Wash the precipitate three times with deionized water and heat-treat it at 600℃ for 140 minutes to obtain oxygen-absorbing porous coal gangue material.

[0057] Example 3

[0058] A method for preparing an oxygen-absorbing porous coal gangue material for preventing combustion in goaf areas includes the following steps:

[0059] S1. Preparation of porous coal gangue materials:

[0060] S1-1. Crush 10g of coal gangue into powder of 200 mesh or higher and add it to excess 2M dilute hydrochloric acid. Stir evenly for 10 minutes and then filter to obtain acid-washed coal gangue.

[0061] S1-2. Mix 5g of pickled coal gangue with 95g of distilled water in a certain proportion and stir evenly for 18min to obtain a coal gangue suspension.

[0062] S1-3. Add 5g of polyvinylpyrrolidone to the coal gangue suspension and stir evenly for 8min under 60℃ water bath heating to obtain coal gangue sol.

[0063] S1-4. Mix 10g of polystyrene microspheres with 40g of distilled water and stir evenly for 14min to obtain a template agent suspension.

[0064] S1-5. Add 20g of template agent suspension to the coal gangue sol dropwise at a dropping rate of 2s / drop, and stir evenly for 80min under a water bath heating at 50℃ to obtain a porous material precursor.

[0065] S1-6. Soak the porous material precursor in tetrahydrofuran and stir evenly for 25 minutes. Wash the filtered sample with distilled water 5 times to obtain the porous coal gangue material.

[0066] S2. Mix 10g of cerium nitrate with 15g of distilled water and stir evenly for 8 minutes to obtain an adsorption solution.

[0067] S3. Mix the porous coal gangue material with the adsorption liquid, stir continuously and evenly, and slowly add 1M ammonia water to control the pH of the solution to 9 to obtain the precipitate.

[0068] S4. Wash the precipitate three times with deionized water and heat-treat it at 600℃ for 150 minutes to obtain oxygen-absorbing porous coal gangue material.

[0069] Example 4

[0070] A method for preparing an oxygen-absorbing porous coal gangue material for preventing combustion in goaf areas includes the following steps:

[0071] S1. Preparation of porous coal gangue materials:

[0072] S1-1. Crush 10g of coal gangue into powder of 200 mesh or higher and add it to excess 1M dilute hydrochloric acid. Stir evenly for 10 minutes and then filter to obtain acid-washed coal gangue.

[0073] S1-2. Mix 5g of pickled coal gangue with 60g of distilled water in a certain proportion and stir evenly for 20min to obtain a coal gangue suspension.

[0074] S1-3. Add 1g of polyvinylpyrrolidone to the coal gangue suspension and stir evenly for 10min under 50℃ water bath heating to obtain coal gangue sol.

[0075] S1-4. Mix 10g of polyacrylic acid microspheres with 60g of distilled water and stir evenly for 15min to obtain a template agent suspension.

[0076] S1-5. Add 15g of template agent suspension to the coal gangue sol dropwise at a dropping rate of 2s / drop, and stir evenly for 60min under a water bath heating at 40℃ to obtain a porous material precursor.

[0077] S1-6. Soak the porous material precursor in dichloromethane and stir evenly for 10 minutes. Wash the filtered sample with distilled water 5 times to obtain the porous coal gangue material.

[0078] S2. Mix 8g of cobalt nitrate with 40g of distilled water and stir evenly for 10 minutes to obtain an adsorption solution.

[0079] S3. Mix the porous coal gangue material with the adsorption liquid, stir continuously and evenly, and slowly add 2M ammonia water to control the pH of the solution to 8 to obtain the precipitate.

[0080] S4. Wash the precipitate five times with deionized water and heat-treat it at 400℃ for 120 minutes to obtain oxygen-absorbing porous coal gangue material.

[0081] The oxygen-type coal gangue porous materials prepared in Examples 1 to 4 were tested for strength and oxygen adsorption capacity. The performance of the porous materials was tested using a press and a fully automated specific surface area and pore size analyzer, respectively. The test results are shown in Table 1 and... Figure 1 As shown.

[0082] Table 1 shows the compressive strength of the porous materials prepared in each embodiment.

[0083] sample Compressive strength (MPa) Example 1 31 Example 2 30 Example 3 32 Example 4 34

[0084] As shown in Table 1, the porous coal gangue material prepared in the above embodiments has high compressive strength. When slurry is injected or deposited on this material, the porous coal gangue material can effectively support the weight of the slurry, preventing it from collapsing or leaking due to its own weight or external forces. The porous structure not only endows the material with good mechanical properties, but may also provide excellent permeability and adsorption, enabling the slurry to be evenly distributed.

[0085] from Figure 1 It can be seen that porous coal gangue materials have good oxygen absorption properties. After high-temperature treatment, the nitrate adsorbent is transformed into an oxide, which can undergo a redox reaction with oxygen. Simultaneously, the adsorbent surface has a large number of oxygen vacancies, which can capture and adsorb oxygen molecules, further increasing its adsorption capacity. The oxygen absorption capacity of Example 3 is significantly higher than that of other examples; this is because cerium oxide can... 4 + and Ce 3The rapid switching between + and + valence states allows for efficient adsorption of oxygen during the reaction. Simultaneously, the abundant oxygen vacancies in cerium oxide can adsorb oxygen and form reactive oxygen species, further enhancing the oxygen absorption capacity. Furthermore, the higher adsorbent concentration in Example 3 further strengthens the adsorption capacity.

[0086] The test results above show that this invention utilizes inexpensive coal gangue to produce an oxygen-absorbing porous material for preventing combustion in goaf areas. The process is simple, achieving waste utilization and turning waste into treasure. The porous material has excellent oxygen absorption properties, removing existing oxygen in the goaf while sealing it, greatly reducing the risk of spontaneous combustion of coal in the goaf. Simultaneously, the good strength of the porous material allows for slurry accumulation, effectively sealing high-level fracture channels to meet the sealing requirements of different conditions in underground coal mines.

Claims

1. A method for preparing an oxygen-absorbing porous coal gangue material for preventing combustion in goaf areas, characterized in that, Includes the following steps: S1. Preparation of porous coal gangue materials; S1-1. Add coal gangue powder pulverized to a finer mesh (greater than 200 mesh) to an excess of dilute hydrochloric acid, stir thoroughly and evenly for 10-15 minutes, and then filter to obtain acid-washed coal gangue. S1-2. Mix pickled coal gangue with distilled water in a certain proportion and stir evenly for 15-20 minutes to obtain a 5-10 wt% coal gangue suspension. S1-3. Add 1.5-5wt% of dispersant to the coal gangue suspension and stir evenly for 5-10 minutes under water bath heating at 50-60℃ to obtain coal gangue sol. S1-4. Mix the template agent with distilled water in a certain proportion and stir evenly for 10-15 minutes to obtain a 10-20 wt% template suspension. S1-5. The template suspension prepared in step S1-4 is added dropwise to the coal gangue sol prepared in step S1-3 at a mass ratio of 1:(1-5). The mixture is stirred evenly for 60-90 minutes under a water bath heating temperature of 40-60℃ to obtain a porous material precursor. S1-6. Soak the porous material precursor in an organic solvent, stir evenly for 10-30 minutes, filter, and wash the filtered sample with distilled water 3-5 times to obtain the porous coal gangue material. S2. Mix a certain proportion of adsorbent with distilled water and stir evenly for 3-10 minutes to obtain a 20-40 wt% adsorption solution. S3. Mix the porous coal gangue material prepared in step S1 with the adsorption liquid prepared in step S2, and slowly add ammonia water while stirring continuously and evenly to control the pH of the solution to 8-10 to obtain a precipitate. S4. Wash the precipitate with deionized water 3-5 times, and heat treat it at 400-600℃ for 120-150 minutes to obtain oxygen-absorbing porous coal gangue material.

2. The method for preparing an oxygen-absorbing porous coal gangue material for preventing combustion in goaf areas according to claim 1, characterized in that, In step S1-1, the concentration of the dilute hydrochloric acid is 1-2M.

3. A method for preparing an oxygen-absorbing porous coal gangue material for preventing combustion in goaf areas according to claim 1 or 2, characterized in that, In steps S1-3, the dispersant is polyvinylpyrrolidone.

4. A method for preparing an oxygen-absorbing porous coal gangue material for preventing combustion in goaf areas according to claim 1 or 2, characterized in that, In steps S1-4, the template agent is one of polyacrylic acid microspheres, polymethyl methacrylate microspheres, and polystyrene microspheres.

5. A method for preparing an oxygen-absorbing porous coal gangue material for preventing combustion in goaf areas according to claim 1 or 2, characterized in that, In steps S1-5, the titration rate of the template agent suspension is 2 s / drop.

6. A method for preparing an oxygen-absorbing porous coal gangue material for preventing combustion in goaf areas according to claim 1 or 2, characterized in that, In steps S1-6, the organic solvent is one of dichloromethane, toluene, and tetrahydrofuran.

7. A method for preparing an oxygen-absorbing porous coal gangue material for preventing combustion in goaf areas according to claim 1 or 2, characterized in that, In step S2, the adsorbent is one of cobalt nitrate, nickel nitrate, or cerium nitrate.

8. A method for preparing an oxygen-absorbing porous coal gangue material for preventing combustion in goaf areas according to claim 1 or 2, characterized in that, In step S3, the ammonia concentration is 1-2M.

9. A method for preparing an oxygen-absorbing porous coal gangue material for preventing combustion in goaf areas according to claim 1 or 2, characterized in that, All stirring is done using magnetic stirring at a speed of 500-1000 rpm.

10. The oxygen-absorbing porous coal gangue material prepared by the preparation method according to any one of claims 1-9 for preventing combustion in goaf areas.

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