Clay stabilized foam high stable gel foam for inhibiting spontaneous combustion of coal and its preparation method

Abstract

The clay-based, highly stable gel foam for inhibiting coal spontaneous combustion of the present invention comprises, by mass percentage: 0.3% compound foaming agent, 3.4% synergistic foam stabilizing gelling agent, 1.7% crosslinking agent, 0.4% pH adjuster, and the balance being deionized water; the synergistic foam stabilizing gelling agent is composed of sodium bentonite (Na-Bt) and sodium alginate (SA) in a mass ratio of 3:0.4. The gel foam prepared by this invention exhibits excellent temperature resistance, water retention, coverage, and fire resistance. It can significantly inhibit coal spontaneous combustion through the combined effect of "synergistic foam stabilization - three-dimensional gelation - heat insulation and water locking." The preparation process is simple and suitable for fire prevention and extinguishing projects in complex environments such as coal mine goaf areas.

Description

Technical Field

[0001] This invention belongs to the field of coal mine fire prevention and extinguishing technology, specifically relating to a clay-stabilized high-stability gel foam for inhibiting spontaneous combustion of coal and its preparation method. Background Technology

[0002] Spontaneous combustion of coal is a major safety hazard in coal mining, easily leading to mine fires, gas explosions, and other accidents, resulting in waste of coal resources and casualties. Foam fire extinguishing technology has become one of the mainstream technologies for fire prevention and extinguishing in coal mines due to its good coverage, rapid cooling, and excellent oxygen isolation effect. However, traditional water-based foam has problems with poor stability and weak temperature resistance. Although pure gel foam improves gelation stability, it has the defects of insufficient foam stabilization effect and easy loss at high temperatures, making it difficult to meet the long-term fire prevention and extinguishing needs of the complex environment of coal mines.

[0003] Currently, existing technologies often add foam stabilizers and gelling agents separately, which lacks synergistic effects and easily leads to poor system compatibility and an imbalance between foam stabilization and gelling effects. For example, while clay foam stabilizers can increase system viscosity when added alone, they lack the ability to gel and form films. Sodium alginate gelling agents, while forming a three-dimensional gel network when added alone, do not provide sufficient foam stabilization durability. Therefore, developing a composite additive that combines foam stabilization and gelling functions to achieve synergistic effects and prepare highly stable, temperature-resistant, and long-lasting gel foam is key to solving the bottleneck of coal mine fire prevention and extinguishing technology. Summary of the Invention

[0004] To address the aforementioned issues, embodiments of this invention propose a clay-based, highly stable gel foam for inhibiting coal spontaneous combustion and its preparation method. Sodium-based bentonite and sodium alginate are combined as a synergistic foam stabilizer and gelling agent, possessing both foam stabilizing and gelling functions, achieving a synergistic effect. The prepared gel foam exhibits suitable gelation time, high stability, and strong temperature and water retention properties, effectively inhibiting coal spontaneous combustion for a long period, thus meeting the application requirements for fire prevention and extinguishing in coal mines.

[0005] The clay-stabilized high-stability gel foam for inhibiting spontaneous combustion of coal of the present invention comprises the following components by mass percentage: 0.3% compound foaming agent, 3.4% synergistic foam stabilizing gelling agent, 1.7% crosslinking agent, 0.4% pH adjuster, and the balance being deionized water;

[0006] The synergistic foam stabilizer is a compound of sodium bentonite (Na-Bt) and sodium alginate (SA) in a mass ratio of 3:0.4.

[0007] Synergistic foam stabilizer: A compound of Na-Bt and SA in a mass ratio of 3:0.4; Na-Bt consists of natural nanosheet particles that can adsorb onto the bubble film to form physical support and increase the system viscosity to achieve foam stabilization; SA is a natural polysaccharide that can react with Ca released by the crosslinking agent. 2+Cross-linking forms a three-dimensional gel network to achieve gelation and film formation; after the two are combined, Na-Bt can fill the gaps in the sodium alginate gel network to form a dense composite structure, which not only improves the mechanical strength and thermal stability of the gel network, but also enhances the foam stability and durability, achieving synergistic effect of foam stability and gelation.

[0008] The compound foaming agent is composed of sodium α-alkenyl sulfonate (AOS) and lauramide propyl betaine (LAB-35) in a mass ratio of 2:1. This ratio results in strong foaming ability, large initial foam volume, and uniform foam diameter, providing a basic foam structure for gel foams.

[0009] The crosslinking agent is an EDTA-CaCl2 composite system formed by chelating disodium ethylenediaminetetraacetate (EDTA) and anhydrous calcium chloride (CaCl2) at a mass ratio of 6.5:2, which can achieve Ca... 2+ Controllable release prevents premature gelation and foaming failure.

[0010] The pH adjuster is D-gluconolactone (GDL), which activates the cross-linking agent to release Ca by slowly adjusting the solution pH. 2+ Precise control of the gelation time of the gel foam ensures both the fluidity of the foam in the pipeline and the coverage effect on the coal body.

[0011] The method for preparing clay-stabilized high-stability gel foam for inhibiting spontaneous combustion of coal according to the present invention includes the following steps:

[0012] S1. Raw material pretreatment: Weigh sodium α-olefin sulfonate AOS and lauramide propyl betaine LAB-35 according to the proportion, and mix them evenly to obtain a compound foaming agent;

[0013] S2. Add sodium alginate SA to the prepared compound foaming agent solution, let it stand for 24 h until it is completely dissolved, and form a uniform foaming agent-gelling agent mixed solution;

[0014] S3. Add sodium-based bentonite (Na-Bt) to the prepared foaming agent-gelling agent mixture and stir thoroughly with an electromagnetic stirrer to dissolve and form a foaming agent-synergistic foam stabilizing gelling agent mixture;

[0015] S4. Weigh out disodium ethylenediaminetetraacetate (EDTA) and anhydrous calcium chloride (CaCl2), add deionized water and stir until completely dissolved to form a stable EDTA-CaCl2 crosslinking agent solution;

[0016] S5. pH adjustment of the crosslinking system: Add sodium hydroxide to the prepared EDTA-CaCl2 crosslinking agent solution to adjust the pH value of the solution to 7-8;

[0017] S6. Construction of composite system: The pH-adjusted EDTA-CaCl2 solution is mixed with the foaming agent-synergistic foam stabilizer gelling agent mixed solution prepared in S3, and stirred until completely dissolved to form a uniform composite base liquid;

[0018] S7. Slowly add D-gluconolactone (GDL) to the composite base liquid and stir continuously until the mixture is uniform, ensuring that all components are in full contact.

[0019] S8. Mechanical foaming: The mixed solution is placed in a foaming device and mechanically foamed at a speed of 1500 r / min. After foaming, a clay-stabilized high-stability gel foam that inhibits spontaneous combustion of coal is obtained.

[0020] The stirring time of the electromagnetic stirrer in S3 is 10 min, and the stirring speed is 700-1000 r / min.

[0021] The foaming time in S8 is 2-4 minutes, until the foam volume stabilizes.

[0022] The beneficial effects of this invention are:

[0023] (1) Synergistic foam stabilizer gelling agent achieves dual functional enhancement: Na-Bt and SA are compounded into a synergistic foam stabilizer gelling agent, breaking through the traditional mode of adding foam stabilizer and gelling agent separately. The physical foam stabilizing effect of sodium bentonite and the chemical gelling effect of sodium alginate form a synergy, which not only solves the problem of insufficient foam stabilization of pure gel foam, but also makes up for the defect of no gelling film formation in pure clay foam stabilization system. The dense structure formed after compounding greatly improves the overall stability and temperature resistance of foam.

[0024] (2) Excellent stability and strong temperature resistance and water retention: The "clay particle-gel network" composite structure formed by the synergistic foam stabilizer significantly prolongs the life of foam in a constant temperature water bath at 100 ℃; when dried in the range of 60-120 ℃, the water loss rate is significantly reduced, and the water-locking and heat-insulating effect is significant.

[0025] (3) Long-lasting coverage and outstanding anti-burning performance: The foam can stably adhere to the surface of the coal for a long time. The dry skeleton remaining after the free water evaporates can still isolate the coal from oxygen and effectively prevent reignition. It takes 40 minutes of high-temperature burning to show obvious indentation, which is far longer than the anti-burning time of water-based foam. In actual coal fire environment, it can effectively suffocate the fire source.

[0026] (4) Suitable gelation time and suitable for field application: Through the synergistic regulation of GDL and crosslinking agent, the gelation time of gel foam is precisely controllable, which can take into account the flowability of foam in coal mine pipelines and the rapid gelation and covering effect after reaching the coal body. The preparation process is simple, no complicated equipment is required, and large-scale preparation and application in coal mines can be realized.

[0027] (5) Environmentally friendly raw materials and controllable cost: The synergistic foam stabilizer uses Na-Bt and SA compounded. The raw materials are widely available, inexpensive and environmentally friendly. There are no toxic or harmful components, and it will not cause secondary pollution to the underground environment and coal resources of the coal mine. It is both economical and environmentally friendly. Attached Figure Description

[0028] Figure 1 This is a flowchart of the preparation method of the clay-stabilized high-stability gel foam for inhibiting spontaneous combustion of coal according to the present invention.

[0029] Figure 2 This shows the change in solution viscosity with clay mass fraction in the solutions prepared from the three types of clay in Example 1.

[0030] Figure 3 In Example 1, the bar graph shows the change in foam volume with the mass fraction of clay, and the dotted line graph shows the change in half-life of the precipitate with the mass fraction of clay.

[0031] Figure 4 This shows the change in the overall foam value with the clay mass fraction in Example 1.

[0032] Figure 5 These are the foam morphologies of the three types of foam in Example 2 under 100°C water bath heating.

[0033] Figure 6 This is a graph showing the volume change and center point temperature change of the three types of foam in Example 2.

[0034] Figure 7 This is a comparison chart of the water loss rates of the three types of foam at different temperatures in Example 2.

[0035] Figure 8 This is a comparison diagram of the effect of foam covering coal particles in Example 3.

[0036] Figure 9 This is the morphology of the foam in Example 3 under high temperature burning.

[0037] Figure 10 This is a comparative experimental diagram showing the inhibitory effects of Clay-GF and Pure-GF on coal spontaneous combustion in Example 4. Detailed Implementation

[0038] Embodiments of the present invention are described in detail below, examples of which are illustrated in the accompanying drawings. The embodiments described below with reference to the accompanying drawings are exemplary and intended to explain the present invention, and should not be construed as limiting the present invention.

[0039] The clay-stabilized high-stability gel foam for inhibiting spontaneous combustion of coal of the present invention comprises the following components by mass percentage: 0.3% compound foaming agent, 3.4% synergistic foam stabilizing gelling agent, 1.7% crosslinking agent, 0.4% pH adjuster, and the balance being deionized water;

[0040] The synergistic foam stabilizer is a compound of sodium bentonite (Na-Bt) and sodium alginate (SA) in a mass ratio of 3:0.4.

[0041] The compound foaming agent is composed of sodium α-olefin sulfonate (AOS) and lauramide propyl betaine (LAB-35) in a mass ratio of 2:1.

[0042] The crosslinking agent is an EDTA-CaCl2 composite system formed by chelating disodium ethylenediaminetetraacetate (EDTA) and anhydrous calcium chloride (CaCl2) at a mass ratio of 6.5:2.

[0043] The pH adjuster is D-gluconolactone (GDL).

[0044] like Figure 1 As shown, the preparation method of the clay-stabilized high-stability gel foam for inhibiting spontaneous combustion of coal according to the present invention includes the following steps:

[0045] S1. Raw material pretreatment: Weigh sodium α-olefin sulfonate AOS and lauramide propyl betaine LAB-35 according to the proportion, and mix them evenly to obtain a compound foaming agent;

[0046] S2. Add sodium alginate SA to the prepared compound foaming agent solution, let it stand for 24 h until it is completely dissolved, and form a uniform foaming agent-gelling agent mixed solution;

[0047] S3. Add sodium bentonite (Na-Bt) to the prepared foaming agent-gelling agent mixture and stir thoroughly with an electromagnetic stirrer to dissolve and form a foaming agent-co-stabilizing gelling agent mixture; the stirring time of the electromagnetic stirrer is 10 min and the stirring speed is 700-1000 r / min.

[0048] S4. Weigh out disodium ethylenediaminetetraacetate (EDTA) and anhydrous calcium chloride (CaCl2), add deionized water and stir until completely dissolved to form a stable EDTA-CaCl2 crosslinking agent solution;

[0049] S5. pH adjustment of the crosslinking system: Add sodium hydroxide to the prepared EDTA-CaCl2 crosslinking agent solution to adjust the pH value of the solution to 7-8;

[0050] S6. Construction of composite system: The pH-adjusted EDTA-CaCl2 solution is mixed with the foaming agent-synergistic foam stabilizer gelling agent mixed solution prepared in S3, and stirred until completely dissolved to form a uniform composite base liquid;

[0051] S7. Slowly add D-gluconolactone (GDL) to the composite base liquid and stir continuously until the mixture is uniform, ensuring that all components are in full contact.

[0052] S8. Mechanical foaming: Place the mixed solution in a foaming device and mechanically foam at a speed of 1500 r / min for 2-4 min until the foam volume stabilizes. After foaming, a clay-stabilized high-stability gel foam that inhibits spontaneous combustion of coal is obtained.

[0053] Example 1

[0054] Experiments on screening clay types and determining their optimal mass fraction.

[0055] Three types of clay (sodium bentonite (Na-Bt), calcium bentonite (Ca-Bt), and kaolin (Kl)) were added to 100 mL of the compound foaming agent solution of this invention, each with a predetermined ratio. The mixtures were stirred using an electromagnetic stirrer to ensure uniform dispersion in the solution system, and the viscosity of the solutions was measured. Each viscosity measurement was repeated three times, and the average value was taken. The results are as follows: Figure 2 As shown, with the increase of clay mass fraction, the Na-Bt group showed the most significant increase in solution viscosity, followed by the Ca-Bt group, while the Kl group showed the worst effect. This result clearly demonstrates that Na-Bt has the most significant thickening effect; therefore, Na-Bt was chosen as the foam-stabilizing component in the synergistic foam stabilizer.

[0056] After determining that the foam-stabilizing component was Na-Bt, it was added to the foaming agent solution and thoroughly mixed. The mixture was then foamed using a foaming device at a speed of 1500 r / min. After foaming, the foam volume and liquid half-life were recorded. Each experiment was repeated three times, and the average of the three values ​​was taken. The overall foam value was calculated using the foam volume and liquid half-life. The results are as follows: Figure 3 and Figure 4 As shown, both the foaming volume and the half-life of the liquid seep out initially increase and then decrease with increasing clay mass fraction. Based on the foaming volume and the half-life of the liquid seep out, the overall foam value was calculated. When the mass fraction of sodium-based bentonite was 3%, the overall foam value was the highest, indicating optimal foaming performance and foam stability. Based on the foaming and foam stability characteristics of the solution, a 3% Na-Bt mass fraction was selected as the foam-stabilizing component of the synergistic foam stabilizer.

[0057] Example 2

[0058] A comparative experiment was conducted on the temperature resistance and water retention properties of three types of gel foam: Clay-GF (with added clay stabilizing components), Pure-GF (without added clay stabilizing components), and Aqueous foam. The gel foam was prepared according to the method of this invention for preparing highly stable clay-stabilized gel foam that inhibits spontaneous combustion of coal.

[0059] Temperature resistance data were obtained through a 100 ℃ constant temperature water bath heating experiment. Thermocouples were used to monitor the temperature change at the center of the foam in real time, and the thermocouple temperature and foam volume data were recorded every 10 minutes. Figures 5-6 As shown in the foam morphology diagram under 100 ℃ water bath heating, the water-based foam, due to the absence of gel, almost completely defoamed after only 70 min of heating at 100 ℃. Pure-GF, after 230 min of heating at 100 ℃, still maintained a considerable volume of stable gel foam with a long survival time, indicating that the introduction of gel greatly enhanced the strength of the foam. Clay-GF, after 230 min of heating at 100 ℃, preserved a larger volume of foam, which appeared denser, and also released less water, indicating that the addition of clay foam-stabilizing components can further enhance the strength of the foam.

[0060] Figure 6 (a) is a comparison of the three volume change curves. It can be seen that the strength increases sequentially from water-based foam to Pure-GF and then to Clay-GF, indicating that the viscosity stabilizing component can further enhance the strength of the gel foam. Figure 6 (b) shows the temperature change curves of the three foam systems. It can be seen that the ordinary water-based foam has the worst thermal insulation performance, with the center temperature reaching 79.5 ℃ at 60 min, and almost all the foam has defoamed. At the same time, the center temperatures of Pure-GF and Clay-GF are 62.1 ℃ and 62.5 ℃, respectively. Pure-GF has a significantly improved thermal insulation performance compared to water-based foam, and its center temperature remains relatively stable after reaching around 80 ℃. The highest temperature at the center of Clay-GF stabilizes at around 78 ℃, further improving its temperature resistance.

[0061] Water retention performance data were obtained through experiments conducted in an electrically heated forced-air drying oven. Figure 7 As can be seen, water-based foam exhibits the highest water loss rate at any drying temperature compared to Pure-GF and Clay-GF gel foams. This is because the cross-linked structure of the gel foam enhances its water-locking ability. At 120 ℃, the water loss of the gel foam initially increases and then remains relatively stable. This is because most of the free water in the gel foam has evaporated within 7-8 hours, leaving only bound water within the gel structure. Even after complete evaporation of free water, the gel foam skeleton can still continue to isolate coal from oxygen, inhibiting spontaneous combustion of coal. Further comparison of Clay-GF and Pure-GF reveals that at four different temperatures, the water loss rate of Clay-GF foam is consistently lower than that of Pure-GF, specifically at 60 ℃, 80 ℃, 100 ℃, and 120 ℃ for 8 hours (as shown in the figures). Figure 7As shown in (a), (b), (c), and (d), the water loss rate of Clay-GF foam decreased by 1.73%, 9.23%, 7.5%, and 2.13%, respectively. This is because the incorporation of clay can form a denser three-dimensional network structure inside the gel foam. On the one hand, it improves the structural strength and thermal stability of the foam skeleton, slows down the foam's rupture rate at high temperatures, and reduces the channels for rapid water loss. On the other hand, clay particles have adsorption properties, which can lock in more water inside the foam. At the same time, the introduction of clay enhances the thermal insulation of the gel foam, reduces the internal temperature of the foam, and further reduces water evaporation.

[0062] Example 3

[0063] A comparative experiment was conducted on the covering performance and fire resistance of Clay-GF and water-based foam. The gel foam preparation method followed the method of this invention for preparing clay-stabilized high-stability gel foam to inhibit coal spontaneous combustion.

[0064] The prepared water-based foam and Clay-GF were uniformly coated on the surface of crushed coal particles (0.5-2 cm in diameter), left to stand at room temperature, and the macroscopic changes of the foam were observed and recorded to compare the covering performance of the water-based foam and Clay-GF. Figure 8 As can be seen, the water-based foam group initially had a small and dense foam volume. However, after 30 minutes, the foam gradually broke down, merged, and increased in size, exposing more and more coal particles to the air. Around 60 minutes, the foam almost completely disappeared, indicating poor coverage. Compared to the water-based foam, Clay-GF initially had a finer foam body. Until 60 minutes, its macroscopic morphology remained almost unchanged, and even after 1 day, the macroscopic morphology of Clay-GF still showed no significant change. It adhered well to the coal particles, with almost no coal particles exposed to the air. This is because the clay-introduced gel foam has a very dense three-dimensional network gel structure, which greatly improves stability and water retention, thus improving the quality of the foam and extending the coverage time. Continuing to leave it until the free water in Clay-GF completely evaporates, leaving a dry foam skeleton covering the coal particles, it can still prevent coal from contacting oxygen, effectively isolating it from oxygen.

[0065] The foamed water-based foam and Clay-GF were poured separately into metal containers with good thermal conductivity. Using a tripod, they were placed above an alcohol lamp, which was then lit. The foam was continuously burned at a fixed point, and the morphological changes of the foam near the heat source were observed and recorded. The heat resistance of the water-based foam and Clay-GF was compared. Figure 9As can be seen, the water-based foam expands rapidly and then bursts quickly. After 10 minutes of burning, localized depressions appeared in the foam near the heat source, and after 20 minutes, large-area depressions appeared. The Clay-GF foam, after slow expansion, gradually shrinks, with a significantly slower rate of volume decay. During the first 20 minutes of burning, no significant defoaming occurred, and no depressions appeared near the heat source. It wasn't until the heating time was extended to 40 minutes that significant depressions appeared in the Clay-GF foam. This indicates that the clay-infused gel foam has superior fire resistance compared to the water-based foam. Furthermore, the gel foam can release a gel liquid during heating, which can suffocate the fire source in a real coal fire environment.

[0066] Example 4

[0067] A comparative experiment was conducted on the inhibitory effects of Clay-GF and Pure-GF on coal spontaneous combustion. The gel foam preparation method followed the method of this invention for preparing clay-stabilized, highly stable gel foam for inhibiting coal spontaneous combustion.

[0068] After the gel foam-treated coal samples and raw coal samples were left at room temperature for 48 hours, thermal analysis was performed using a thermal analysis instrument under a dry air stream. The results are as follows: Figure 10 As shown in the figure. T1 is the temperature point corresponding to the maximum water loss rate during the heating process, and DTG1 is the maximum water loss rate. Figure 10 (a) The T1 of the raw coal is 90.694 ℃, and the DTG1 is -0.078 % / ℃. Figure 10 (b) The T1 of the coal sample treated with Pure-GF was 94.249 ℃, and the DTG1 was -0.076 % / ℃. Figure 10 (c) The T1 of the Clay-GF treated coal sample was 99.308 ℃, and the DTG1 was -0.062 % / ℃. Compared with the raw coal, the T1 of the Pure-GF treated coal sample increased by 3.555 ℃, and the DTG1 decreased by 0.002 % / ℃. Compared with Pure-GF, the T1 of the Clay-GF treated coal sample further increased by 5.059 ℃, and the maximum water loss rate decreased by 0.014 % / ℃. This is because the moisture in the raw coal is mostly in a free state, which is easily and quickly removed by heating. However, the polymer gel network of the gel foam will encapsulate and bind the moisture as bound water, requiring a higher temperature to overcome the gel network forces to remove the moisture.

[0069] The three-dimensional network structure of the clay-infused gel foam can more firmly trap water molecules inside, further improving water retention and enhancing the cooling effect of water. T2 is the temperature at which the coal loses the most weight, and DTG2 is the maximum weight loss rate during the combustion weight loss stage. The T2 of raw coal is 344.994 ℃, and DTG2 is 48.205%. The T2 of coal samples treated with Pure-GF is 349.949 ℃, and DTG2 is 50.557%. The T2 of coal samples treated with Clay-GF is 363.908 ℃, and DTG2 is 53.132%. Pure-GF increased the T2 by 4.955 ℃ and the DTG2 by 2.352% compared to raw coal. This is because the skeleton left by the gel foam after water loss forms a protective film on the coal surface, which has a certain inhibitory effect on coal combustion. Compared with Pure-GF, Clay-GF showed a significant increase in T2 of 13.959 ℃ and TG2 of 2.575%, indicating that the introduction of gel foam into clay resulted in superior water retention, coverage, and inhibition of coal combustion.

[0070] Although the above embodiments have been shown and described, it is understood that the above embodiments are exemplary and should not be construed as limiting the present invention. Any changes, modifications, substitutions and variations made to the above embodiments by those skilled in the art are within the protection scope of the present invention.

Claims

1. A clay-based, highly stable gel foam for inhibiting spontaneous combustion of coal, characterized in that, By weight percentage, it includes the following components: 0.3% compound foaming agent, 3.4% synergistic foam stabilizer, 1.7% crosslinking agent, 0.4% pH adjuster, and the balance being deionized water; The synergistic foam stabilizer is a compound of sodium bentonite (Na-Bt) and sodium alginate (SA) in a mass ratio of 3:0.

4.

2. The clay-stabilized, highly stable gel foam for inhibiting spontaneous combustion of coal according to claim 1, characterized in that, The compound foaming agent is composed of sodium α-olefin sulfonate (AOS) and lauramide propyl betaine (LAB-35) in a mass ratio of 2:

1.

3. The clay-stabilized, highly stable gel foam for inhibiting spontaneous combustion of coal according to claim 2, characterized in that, The crosslinking agent is an EDTA-CaCl2 composite system formed by chelating disodium ethylenediaminetetraacetate (EDTA) and anhydrous calcium chloride (CaCl2) at a mass ratio of 6.5:

2.

4. The clay-stabilized, highly stable gel foam for inhibiting spontaneous combustion of coal according to claim 3, characterized in that, The pH adjuster is D-gluconolactone (GDL).

5. A method for preparing a clay-stabilized, highly stable gel foam for inhibiting spontaneous combustion of coal according to claim 4, characterized in that, Includes the following steps: S1. Raw material pretreatment: Weigh sodium α-olefin sulfonate AOS and lauramide propyl betaine LAB-35 according to the proportion, and mix them evenly to obtain a compound foaming agent; S2. Add sodium alginate SA to the prepared compound foaming agent solution, let it stand for 24 h until it is completely dissolved, and form a uniform foaming agent-gelling agent mixed solution; S3. Add sodium-based bentonite (Na-Bt) to the prepared foaming agent-gelling agent mixture and stir thoroughly with an electromagnetic stirrer to dissolve and form a foaming agent-synergistic foam stabilizing gelling agent mixture; S4. Weigh out disodium ethylenediaminetetraacetate (EDTA) and anhydrous calcium chloride (CaCl2), add deionized water and stir until completely dissolved to form a stable EDTA-CaCl2 crosslinking agent solution; S5. pH adjustment of the crosslinking system: Add sodium hydroxide to the prepared EDTA-CaCl2 crosslinking agent solution to adjust the pH value of the solution to 7-8; S6. Construction of composite system: The pH-adjusted EDTA-CaCl2 solution is mixed with the foaming agent-synergistic foam stabilizer gelling agent mixed solution prepared in S3, and stirred until completely dissolved to form a uniform composite base liquid; S7. Slowly add D-gluconolactone (GDL) to the composite base liquid and stir continuously until the mixture is uniform, ensuring that all components are in full contact. S8. Mechanical foaming: The mixed solution is placed in a foaming device and mechanically foamed at a speed of 1500 r / min. After foaming, a clay-stabilized high-stability gel foam that inhibits spontaneous combustion of coal is obtained.

6. The method for preparing clay-stabilized high-stability gel foam for inhibiting spontaneous combustion of coal according to claim 5, characterized in that, The stirring time of the electromagnetic stirrer in S3 is 10 min, and the stirring speed is 700-1000 r / min.

7. The method for preparing clay-stabilized high-stability gel foam for inhibiting spontaneous combustion of coal according to claim 5, characterized in that, The foaming time in S8 is 2-4 minutes, until the foam volume stabilizes.

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