Self-healing inhibitor for inhibiting spontaneous combustion of coal and application thereof

Abstract

This invention provides a self-healing inhibitor for suppressing coal spontaneous combustion and its application, belonging to the field of inhibitor technology. The self-healing inhibitor for suppressing coal spontaneous combustion comprises a gel-based liquid and a crosslinking agent; the gel-based liquid is prepared from the following raw materials: sodium alginate solution, gelatin, polyvinyl alcohol, and a plasticizer; the crosslinking agent is a calcium chloride-saturated borax solution. When used, the crosslinking agent of the inhibitor provided by this invention crosslinks with the gel-based liquid to form a thin film. This crosslinked film has properties such as water retention, reabsorption and swelling, and oxygen barrier, which can effectively reduce the temperature of the coal and inhibit the occurrence of coal spontaneous combustion.

Description

Technical Field

[0001] This invention relates to the field of inhibitor technology, and in particular to a self-healing inhibitor for inhibiting spontaneous combustion of coal and its application. Background Technology

[0002] Spontaneous combustion of coal seams can easily trigger secondary disasters such as gas explosions and coal dust explosions, causing serious casualties and economic losses, making it a key and difficult point in mine fire prevention and control. To suppress spontaneous combustion of coal, researchers have developed various technical measures, mainly including water, air, gas, and grout. While these traditional fire prevention and extinguishing technologies use simple and readily available materials, they only have relative performance advantages against spontaneous combustion in specific environments and have limited adaptability to different environments and conditions. They are suitable for regional coal spontaneous combustion prevention and control, but their targeting is relatively low. Inert gas methods for preventing spontaneous combustion of coal mainly involve injecting gaseous or liquid CO2 or N2 into the hazardous area or fire zone of the coal seam. However, inert gas inhibitors require a high degree of spatial sealing and are greatly affected by airflow, making the suppression effect difficult to control. Grouting technology is prone to problems such as pipe blockage, grout leakage, grout collapse, and trenching. Water and solid substances separate, making it impossible to uniformly fill and cover the hazardous area. Furthermore, the grout has poor water retention and requires a large amount of soil, causing serious environmental damage.

[0003] In response to these problems, experts and scholars have successively developed new coal fire prevention and extinguishing technologies based on theoretical research on the mechanism of coal spontaneous combustion. Among them, the fire prevention and extinguishing technology using fire inhibitors has received widespread attention and shows great potential for development and application.

[0004] Based on the theory of coal-oxygen interaction, spontaneous combustion of coal is attributed to the adsorption of oxygen by coal and the heat generated during coal-oxygen interaction. The physical adsorption of oxygen by coal is a prerequisite for spontaneous combustion of coal. That is, the low-temperature oxidation stage of coal is the key stage in the occurrence and development of spontaneous combustion of coal. The exothermic oxidation at this stage is the fundamental cause of spontaneous combustion of coal. Therefore, inhibiting the low-temperature oxidation of coal is the key to preventing spontaneous combustion of coal.

[0005] Currently, fire inhibitors mainly include halides, ammonium salts, and colloids. Halides and ammonium salts form a liquid film on the coal surface due to their strong water absorption, playing a role in moisture absorption and cooling. However, these fire inhibitors only have an inhibitory effect in the early stages of coal oxidation, have poor heat resistance, and are somewhat corrosive, damaging underground equipment and human health. Colloidal fire inhibitors are colloidal materials such as water glass that are transported to areas with spontaneous combustion risks, such as goaf areas, through pumping, filling, and vibration. Utilizing the water retention, viscosity, and solidification properties of colloids, they can isolate oxygen, absorb moisture and cool, and block air leaks, thus inhibiting spontaneous combustion of coal. However, as the coal temperature rises, the water retention of colloidal materials decreases rapidly, and shrinkage and cracking occur after water loss, making it difficult to achieve a long-lasting fire prevention and extinguishing effect against spontaneous combustion.

[0006] Improving the inhibition effect of existing inhibitors and delaying or suppressing the oxidation and spontaneous combustion process of coal has become a pressing technical challenge in this field. Summary of the Invention

[0007] The purpose of this invention is to provide a self-healing inhibitor for suppressing coal spontaneous combustion and its preparation method. The self-healing inhibitor provided by this invention is a highly water-retaining, water-absorbing, swelling colloid with good thermal stability, adhesion, oxygen barrier properties, and self-healing ability. It is also environmentally friendly, enabling it to exert a good inhibitory effect and delay the process of coal oxidation and spontaneous combustion.

[0008] To achieve the above-mentioned objectives, the present invention provides the following technical solution:

[0009] This invention provides a self-healing inhibitor for suppressing spontaneous combustion of coal, comprising a gel-based liquid and a crosslinking agent;

[0010] The gel-based liquid is prepared from the following raw materials: sodium alginate solution, gelatin, polyvinyl alcohol and plasticizer;

[0011] The crosslinking agent is a calcium chloride saturated borax solution.

[0012] Preferably, the mass ratio of the gelatin to the sodium alginate solution is 1:(1-6).

[0013] Preferably, the mass ratio of the gelatin to the sodium alginate solution is 1:2.

[0014] Preferably, the mass ratio of polyvinyl alcohol to sodium alginate in the sodium alginate solution is 1:(1-6).

[0015] Preferably, the mass ratio of polyvinyl alcohol to sodium alginate in the sodium alginate solution is 1:2.

[0016] Preferably, the mass of the plasticizer is 10-50 wt% of the total mass of sodium alginate, gelatin, and polyvinyl alcohol in the sodium alginate solution.

[0017] Preferably, the mass of the plasticizer is 20-40 wt% of the total mass of sodium alginate, gelatin, and polyvinyl alcohol in the sodium alginate solution.

[0018] Preferably, the mass concentration of the calcium chloride saturated borax solution is 1 wt% to 5 wt%.

[0019] Preferably, the mass concentration of the calcium chloride saturated borax solution is 2wt% to 4wt%.

[0020] This invention also provides the application of the self-healing inhibitor described in the above-mentioned technical solution for inhibiting spontaneous combustion of coal in the inhibition of spontaneous combustion of coal, comprising the following steps:

[0021] (1) Mix the gel-based liquid with coal to obtain a coal sample;

[0022] (2) Spray the crosslinking agent onto the surface of the coal sample obtained in step (1).

[0023] This invention provides a self-healing inhibitor for suppressing coal spontaneous combustion, comprising a gel-based liquid and a crosslinking agent. The gel-based liquid is prepared from the following raw materials: sodium alginate solution, gelatin, polyvinyl alcohol, and a plasticizer; the crosslinking agent is a calcium chloride-saturated borax solution. When used, the crosslinking agent of this invention crosslinks with the gel-based liquid to form a thin film. This crosslinked film possesses properties such as water retention, reabsorption and swelling, and oxygen barrier, effectively reducing the coal temperature and inhibiting spontaneous combustion. Experimental results show that the amount of CO gas generated during the oxidation process of the coal samples treated with the inhibitor is significantly lower than that of the raw coal. Attached Figure Description

[0024] Figure 1 This invention relates to the self-healing mechanism of the self-healing inhibitor.

[0025] Figure 2 The microstructure of sodium alginate in Example 1;

[0026] Figure 3 The microstructure of the gel-based liquid in Example 1;

[0027] Figure 4 The microstructure of the self-healing inhibitor for suppressing coal spontaneous combustion prepared in Example 1 is shown.

[0028] Figure 5 The oxygen permeability of the sodium alginate solution, gel base liquid, and self-healing inhibitor for inhibiting coal spontaneous combustion in Example 1;

[0029] Figure 6 The water loss rate of the inhibitors prepared in Examples 1-5 at room temperature;

[0030] Figure 7 The water loss rate of the inhibitors prepared in Examples 1-5 under heating conditions;

[0031] Figure 8 The water absorption ratio of the inhibitors prepared in Examples 1-5 after drying at room temperature;

[0032] Figure 9 This describes the self-healing process of the inhibitor in Example 1;

[0033] Figure 10 To compare the curves of CO gaseous products changing with temperature in the lignite raw coal of Application Example 1 and the inhibited coal sample of Application Example 1;

[0034] Figure 11 To compare the CO gaseous products of the raw coal and the inhibited coal sample of Application Example 2 with temperature. Detailed Implementation

[0035] This invention provides a self-healing inhibitor for suppressing spontaneous combustion of coal, comprising a gel-based liquid and a crosslinking agent;

[0036] The gel-based liquid is prepared from the following raw materials: sodium alginate solution, gelatin, polyvinyl alcohol and plasticizer;

[0037] The crosslinking agent is a calcium chloride saturated borax solution.

[0038] Unless otherwise specified, the present invention does not impose any special restrictions on the source of each raw material, and commercially available products or well-known preparation methods familiar to those skilled in the art can be used for preparation.

[0039] In this invention, the self-healing inhibitor comprises a gel-based liquid; the gel-based liquid is prepared from raw materials including sodium alginate solution, gelatin, polyvinyl alcohol and plasticizer.

[0040] In this invention, the raw material for preparing the gel base liquid includes sodium alginate solution. Preferably, the sodium alginate solution is prepared by mixing sodium alginate with distilled water; the mass concentration of the sodium alginate solution is preferably 0.5 wt% to 3 wt%, more preferably 2 wt%. In this invention, sodium alginate (SA) is a non-toxic, pale yellow powder, natural polymer compound. The sodium ions in the G segment of the sodium alginate molecule readily exchange with calcium ions, forming an "egg-box" structure between the sodium alginate segments (as shown in Formula I), resulting in a highly stable gel. Sodium alginate can be crosslinked with CaCl2 solution. Gelatin (GEL) has strong hygroscopic capacity, excellent properties, good biocompatibility, good film-forming properties, and high stability. It can be used as a thickener in blends with sodium alginate to increase the viscosity of the inhibitor and produce a synergistic effect.

[0041]

[0042] In this invention, the raw materials for preparing the gel-based liquid also include gelatin, preferably gelatin particles. In this invention, the gelatin (GEL) has strong hygroscopic capacity, good biocompatibility, good film-forming properties, and high stability. It can be used as a thickener in blends with sodium alginate to increase the viscosity of the inhibitor and produce a synergistic effect.

[0043] In this invention, the raw materials for preparing the gel-based liquid also include polyvinyl alcohol; the polyvinyl alcohol is preferably polyvinyl alcohol powder. In this invention, polyvinyl alcohol (PVA) is a non-toxic, non-irritating polymer with excellent biodegradability, film-forming properties, barrier properties, and adhesive strength. It can be used to improve the high brittleness and poor elasticity of inhibitors, thereby improving the mechanical properties of the inhibitors. The hydroxyl groups in polyvinyl alcohol can cross-link with the borate ions in borax molecules to generate reversible dynamic covalent borate ester bonds, giving the inhibitor good self-healing properties.

[0044] In this invention, the raw materials for preparing the gel-based liquid also include a plasticizer; the plasticizer is preferably glycerol. In this invention, the plasticizer can improve the elongation and flexibility of the inhibitor; glycerol is non-toxic, inexpensive, and has a significant plasticizing effect.

[0045] In this invention, the mass ratio of gelatin to sodium alginate in the sodium alginate solution is 1:(1-6), more preferably 1:2; the mass ratio of polyvinyl alcohol to sodium alginate in the sodium alginate solution is preferably 1:(1-6), more preferably 1:2; the mass of the plasticizer is preferably 10-50 wt% of the total mass of sodium alginate, gelatin and polyvinyl alcohol in the sodium alginate solution, more preferably 20-40 wt%, more preferably 30 wt%.

[0046] In this invention, the preparation method of the gel-based liquid preferably includes the following steps:

[0047] 1) Slowly add gelatin to sodium alginate solution to obtain SA / GE mixed solution;

[0048] 2) Slowly add polyvinyl alcohol to the SA / GE mixed solution obtained in step 1) to obtain an SA / GE / PVA mixed solution;

[0049] 3) Add the plasticizer dropwise to the SA / GE / PVA mixed solution obtained in step 2) to obtain a gel-based solution.

[0050] In this invention, gelatin is preferably added slowly to the sodium alginate solution to obtain an SA / GE mixed solution. The slow addition of gelatin in this invention ensures thorough and uniform mixing of the raw materials.

[0051] The present invention does not have any special limitations on the operation of slow addition; any operation known to those skilled in the art can be used.

[0052] After obtaining the SA / GE mixed solution, the present invention preferably adds polyvinyl alcohol slowly to the SA / GE mixed solution to obtain an SA / GE / PVA mixed solution. The slow addition of polyvinyl alcohol in the present invention ensures thorough and uniform mixing of the raw materials.

[0053] The present invention does not have any special limitations on the operation of slow addition; any operation known to those skilled in the art can be used.

[0054] After obtaining the SA / GE / PVA mixed solution, the present invention adds the plasticizer dropwise into the SA / GE / PVA mixed solution. The dropwise addition method used in the present invention ensures thorough and uniform mixing of the raw materials.

[0055] The present invention does not impose any special limitation on the dripping rate; any operation familiar to those skilled in the art can be used.

[0056] In this invention, the self-healing inhibitor further includes a crosslinking agent; the crosslinking agent is a calcium chloride saturated borax solution. In this invention, the mass concentration of the calcium chloride saturated borax solution is preferably 1 wt% to 5 wt%, more preferably 2 wt% to 4 wt%; the calcium chloride saturated borax solution is preferably prepared by mixing calcium chloride, borax, and water. In this invention, the calcium chloride saturated borax solution is used as a crosslinking agent; calcium chloride is used to crosslink sodium alginate, and borax is used to crosslink polyvinyl alcohol, thereby enabling the inhibitor to form a double-network formation mechanism (sodium alginate in the inhibitor undergoes ionic crosslinking with calcium chloride in the crosslinking agent, while polyvinyl alcohol and borax undergo crosslinking, forming a relatively uniform and regular porous structure within the inhibitor system; the interpenetrating double-network structure with interconnected and entangled pores gives the inhibitor excellent properties of high water retention and water absorption swelling).

[0057] In this invention, the mass ratio of gel base liquid to crosslinking agent is preferably (12-9):1, more preferably 10:1.

[0058] The inhibitor of the present invention coats the surface of coal, and through the excellent properties of the inhibitor, achieves the purpose of inhibiting spontaneous combustion of coal.

[0059] The inhibitor of this invention generates a reversible dynamic covalent boron ester bond (e.g., borate ions in the crosslinking agent undergo a complexation reaction with the hydroxyl groups of polyvinyl alcohol that are close to each other) to form a boron ester bond. Figure 1 As shown in the figure, this endows the inhibitor with good self-healing properties; the self-healing ability of the inhibitor solves the problem of breakage during transportation of traditional inhibitors, greatly improves the inhibitor's inhibition life, durability and reliability, increases the coverage of the coal body, wets and coats the coal body surface, forms an oxygen-barrier film, and has the ability to prevent coal spontaneous combustion for a long time.

[0060] The self-healing inhibitor provided by this invention is a highly water-retaining, water-absorbing and swelling colloid with good thermal stability, adhesion, oxygen barrier properties and self-healing ability, and is also environmentally friendly, enabling it to exert a good inhibitory effect and delay and inhibit the oxidation and spontaneous combustion process of coal.

[0061] This invention also provides the application of the self-healing inhibitor described in the above-mentioned technical solution for inhibiting spontaneous combustion of coal in the inhibition of spontaneous combustion of coal, comprising the following steps:

[0062] (1) Mix the gel-based liquid with coal to obtain a coal sample;

[0063] (2) Spray the crosslinking agent onto the surface of the coal sample obtained in step (1).

[0064] This invention involves mixing a gel-based liquid with coal to obtain a coal sample.

[0065] In this invention, the mass ratio of the gel-based liquid to coal is preferably 1:(2-6), and more preferably 1:4.

[0066] The present invention does not have any special limitations on the operation of mixing the gel-based liquid with coal; any operation known to those skilled in the art can be used.

[0067] After obtaining the coal sample, the present invention sprays a crosslinking agent onto the surface of the coal sample.

[0068] The present invention does not impose any special limitations on the spraying operation; any operation known to those skilled in the art can be used.

[0069] The present invention does not impose a specific limitation on the crosslinking temperature; room temperature is sufficient. The present invention also does not impose a specific limitation on the crosslinking time; the time required is sufficient to form a film capable of inhibiting spontaneous combustion of coal.

[0070] This invention involves spraying a crosslinking agent onto the surface of a coal sample prepared from a gel-based liquid and coal. The crosslinking agent crosslinks the surface to form an SA / GE / PVA / GL film. This crosslinked film has properties such as water retention, reabsorption of water and swelling, and oxygen isolation, which can effectively reduce the temperature of the coal and inhibit spontaneous combustion of coal.

[0071] The technical solutions of this invention will be clearly and completely described below with reference to the embodiments thereof. Obviously, the described embodiments are only a part of the embodiments of this invention, and not all of them. All other embodiments obtained by those skilled in the art based on the embodiments of this invention without creative effort are within the scope of protection of this invention.

[0072] Example 1

[0073] The self-healing inhibitor that suppresses spontaneous combustion of coal consists of a gel-based liquid and a crosslinking agent;

[0074] The gel-based liquid is prepared from the following raw materials: sodium alginate solution, gelatin particles, polyvinyl alcohol powder, and glycerol;

[0075] The mass ratio of sodium alginate to gelatin particles and polyvinyl alcohol powder in the sodium alginate solution is 2:1:1.

[0076] The mass of the glycerol is 30 wt% of the total mass of sodium alginate, gelatin granules and polyvinyl alcohol powder;

[0077] The crosslinking agent is a 2 wt% calcium chloride saturated borax solution;

[0078] The mass ratio of the gel base liquid to the crosslinking agent is 10:1;

[0079] The preparation method of the gel-based liquid is as follows:

[0080] (1) Add 6g of sodium alginate powder to 300mL of 60℃ distilled water, stir well, and obtain sodium alginate solution;

[0081] (2) Weigh 3g of gelatin granules and slowly add them to the sodium alginate solution while stirring until they are completely dissolved to obtain a SA / GE mixed solution.

[0082] (3) Weigh 3g of polyvinyl alcohol powder and slowly add it to the SA / GE mixed solution while stirring. Continue stirring until dissolved to obtain the SA / GE / PVA mixed solution.

[0083] (4) Add glycerol dropwise to the SA / GE / PVA mixed solution, continue stirring, mix evenly, and obtain the gel base solution.

[0084] Example 2

[0085] Based on Example 1, the concentration of the calcium chloride saturated borax solution was replaced with 1 wt%, while other conditions remained unchanged, to obtain a self-healing inhibitor that suppresses spontaneous combustion of coal.

[0086] Example 3

[0087] Based on Example 1, the concentration of the calcium chloride saturated borax solution was replaced with 3 wt%, while other conditions remained unchanged, to obtain a self-healing inhibitor that suppresses spontaneous combustion of coal.

[0088] Example 4

[0089] Based on Example 1, the concentration of the calcium chloride saturated borax solution was replaced with 4 wt%, while other conditions remained unchanged, to obtain a self-healing inhibitor that suppresses spontaneous combustion of coal.

[0090] Example 5

[0091] Based on Example 1, the concentration of the calcium chloride saturated borax solution was replaced with 5 wt%, while other conditions remained unchanged, to obtain a self-healing inhibitor that suppresses spontaneous combustion of coal.

[0092] The crosslinking agents in Examples 1 to 5 were sprayed onto the surface of the gel-based liquid to perform crosslinking, thereby obtaining a self-healing inhibitor that inhibits spontaneous combustion of coal.

[0093] The sodium alginate solution, gel base liquid (SA / GE / PVA / GL), and self-healing inhibitor for suppressing coal spontaneous combustion (SA / GE / PVA / GL + crosslinking agent) from Example 1 were used in a cryogenic transport system (Quorum-pp3010) and a focused ion beam field emission scanning electron microscope (FEI-Helios5). After freeze-drying the samples in vacuum and sputter-coating with gold, the samples were transported into the electron microscope chamber for observation of their microstructure under low-temperature conditions. The results are as follows: Figures 2-4 As shown, where, Figure 2 The microstructure of sodium alginate in Example 1; Figure 3 The image shows the microstructure of the gel-based liquid in Example 1. Figure 4 The image shows the microstructure of the self-healing inhibitor for suppressing spontaneous combustion of coal prepared in Example 1.

[0094] from Figures 2-4 It can be seen that the sodium alginate surface is smooth and flat, while the gel-based liquid surface has wrinkles and does not form a network structure. The inhibitor surface forms a relatively dense porous interpenetrating double network structure, which is distributed throughout the entire inhibitor surface. This three-dimensional network structure is the main channel for water molecules to enter and exit the inhibitor. The network structure formed inside the inhibitor helps to improve the inhibitor's water retention and swelling capacity, which helps to persistently reduce the coal body temperature and improve the effect of inhibiting coal spontaneous combustion.

[0095] The oxygen permeability coefficients of the sodium alginate solution, gel-based liquid, and self-healing inhibitor for suppressing coal spontaneous combustion in Example 1 were determined using the differential pressure method. The oxygen barrier performance was compared and analyzed, and the results are as follows: Figure 5 As shown.

[0096] from Figure 5 It can be seen that the oxygen permeability coefficient of sodium alginate is 1.21 × 10⁻⁶. -9 cm 3 ·cm / cm 2 The oxygen permeability coefficient of the gel-based solution is 0.84 × 10⁻⁶ Pa·s. -9 cm 3 ·cm / cm 2 The oxygen permeability coefficient of the inhibitor is the lowest at 0.29 × 10⁻⁶ Pa. -9 cm 3 ·cm / cm 2 The value of ·s·Pa indicates that the gel-based liquid of the sprayed crosslinking agent has strong oxygen-barrier properties, forming an oxygen-barrier film on the coal surface that effectively prevents oxygen from contacting the coal, thereby reducing the probability of spontaneous combustion of coal.

[0097] The water loss rates of the inhibitors prepared in Examples 1-5 were tested under room temperature and elevated temperature conditions (30°C, 40°C, 50°C, 60°C, 70°C, 80°C, 90°C), and the results are as follows: Figure 6 and 7 As shown.

[0098] from Figure 6 and 7 It can be seen that under both ambient and elevated temperatures, the water loss rate of the inhibitor gradually decreases with increasing crosslinking agent concentration, indicating that crosslinking occurs between the gel base liquid and the crosslinking agent. The interpenetrating double network structure formed by the inhibitor can prevent water loss. The water loss rate of the inhibitor after 26 hours at ambient temperature is 23.8%. The water loss rates of the inhibitor at 70℃ and 90℃ are 21.7% and 38.55%, respectively, indicating that the inhibitor has strong water retention and certain heat resistance. The low-temperature oxidation stage of coal mainly occurs between ambient and 70℃; therefore, the inhibitor can effectively reduce the coal temperature, thereby delaying the occurrence and development of spontaneous combustion.

[0099] The water absorption ratio of the inhibitors prepared in Examples 1-5 after drying at room temperature was tested, and the results are as follows: Figure 8 As shown.

[0100] from Figure 8 It can be seen that the five inhibitors exhibit a consistent trend in water absorption and swelling over time. In the initial stage of water absorption and swelling, the hydrophilic groups in the inhibitors result in a high water absorption and swelling rate. However, as the water absorption increases, the chemical adsorption between the hydrophilic groups and water molecules weakens, and the diffusion rate of water molecules is restricted by the gel's spatial network, resulting in water being stored within the hydrogel network and forming free water. When a sufficient number of water molecules enter the network, the network structure enlarges to its limit, at which point the gel tends to become saturated with water, reaching a swelling equilibrium, and the swelling rate remains essentially unchanged. The concentration of the crosslinking agent has a significant impact on the water absorption and swelling characteristics of the inhibitors. The inhibitor with 2wt% crosslinking agent exhibits the highest water absorption ratio, reaching 37.73 g / g. The higher the concentration of the crosslinking agent, the lower the water absorption rate of the inhibitor. This is because an excessively high concentration of the crosslinking agent will lead to an increase in the number of crosslinking points and an excessively high crosslinking density in the inhibitor. The resulting network structure will have smaller micropores, which will not have enough space to accommodate water molecules. Water molecules will not easily enter the interior of the network structure, resulting in a decrease in the water absorption rate. After reabsorption, the inhibitor will cover the surface of the coal body, thereby repeatedly wetting the coal body and lowering the coal temperature, achieving the purpose of long-term inhibition of coal oxidation and spontaneous combustion.

[0101] When the inhibitor of Example 1 is cut open and then brought into contact with the material, it can self-repair and heal together (e.g., Figure 9 As shown, Figure 9This describes the self-healing process of the inhibitor in Example 1, and it exhibits a certain tensile strength. This is mainly due to the complexation reaction between borate ions in the crosslinking agent and the hydroxyl groups of polyvinyl alcohol that are close to each other, generating reversible dynamic covalent boron ester bonds. This endows the inhibitor with good self-healing properties, solving the problem of breakage during transportation of traditional inhibitors. It greatly improves the inhibitor's inhibition life, durability, and reliability, increases the coverage of the coal body, wets and coats the coal surface, forming an oxygen-barrier film, and has the ability to prevent coal spontaneous combustion in a long time.

[0102] Application Example 1

[0103] The gel-based liquid from Example 1 was added to the raw lignite at a mass ratio of 1:4. After stirring and mixing evenly, a 2wt% calcium chloride saturated borax solution was sprayed onto the surface of the coal sample. After standing in a cool, dark place and sealing for 12 hours, the sample was placed in a vacuum drying oven and dried at a constant temperature of 30°C until constant weight was obtained, thus obtaining the inhibited coal sample.

[0104] Comparative Application Example 1

[0105] Take 80g of raw lignite and place it in a vacuum drying oven. Dry it at a constant temperature of 30℃ until it reaches a constant weight.

[0106] A programmed temperature rise-gas chromatography (PCC) system was used, with the furnace heating rate set at 0.5℃ / min and the gas flow rate at 120mL / min. The test temperature was raised from room temperature to 250℃. Gases produced by coal oxidation at different temperatures were collected, and CO was detected by gas chromatography.

[0107] The curves showing the change of CO gaseous products with temperature between the raw lignite of Application Example 1 and the inhibited coal sample of Application Example 1 are shown below. Figure 10 As shown.

[0108] from Figure 10 It can be seen that, under isothermal conditions, there are significant differences in the amount of CO gas released during the low-temperature oxidation process between raw lignite and inhibited coal samples. The amount of CO gas released during the oxidation process of the inhibited coal samples is significantly lower than that of the raw coal, and the initial temperature of CO production increases from 50℃ for the raw coal to 90℃.

[0109] Application Example 2

[0110] The self-healing inhibitor prepared in Example 1 was added to the raw gas coal at a mass ratio of 1:4. After stirring and mixing evenly, a 2wt% calcium chloride saturated borax solution was sprayed onto the surface of the coal sample. After standing in a cool place and being sealed and stored for 12 hours, the sample was placed in a vacuum drying oven and dried at a constant temperature of 30°C until constant weight was obtained, thus obtaining the inhibited coal sample.

[0111] Comparative Application Example 2

[0112] Take 80g of raw gas coal, place it in a vacuum drying oven, and dry it at a constant temperature of 30℃ until it reaches a constant weight.

[0113] A programmed temperature rise-gas chromatography (PCC) system was used, with the furnace heating rate set at 0.5℃ / min and the gas flow rate at 120mL / min. The test temperature was raised from room temperature to 250℃. Gases produced by coal oxidation at different temperatures were collected, and CO was detected by gas chromatography.

[0114] The curves showing the change of CO gaseous products with temperature between the raw gas coal of Application Example 2 and the inhibited coal sample of Application Example 2 are as follows: Figure 11 As shown.

[0115] from Figure 11 It can be seen that, under isothermal conditions, there are significant differences in the amount of CO gas produced during the low-temperature oxidation process between raw gas coal and inhibited coal samples. The amount of CO gas produced during the oxidation process of the inhibited coal samples is significantly lower than that of the raw coal, and the initial temperature of CO production increases from 60℃ for the raw coal to 100℃.

[0116] As can be seen from the above embodiments, the self-healing inhibitor provided by the present invention is a highly water-retaining, water-absorbing and swelling colloid with good thermal stability, adhesion, oxygen barrier and self-healing ability, and is environmentally friendly, which enables it to exert a good inhibitory effect and delay and inhibit the oxidation and spontaneous combustion process of coal.

[0117] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A self-healing inhibitor for suppressing spontaneous combustion of coal, comprising a gel-based liquid and a crosslinking agent; The gel-based liquid is prepared from the following raw materials: sodium alginate solution, gelatin, polyvinyl alcohol and plasticizer; The crosslinking agent is a calcium chloride saturated borax solution; The mass ratio of the gelatin to the sodium alginate solution is 1:(1~6). The mass ratio of polyvinyl alcohol to sodium alginate in the sodium alginate solution is 1:(1~6). The plasticizer is 10-50 wt% of the total mass of sodium alginate, gelatin, and polyvinyl alcohol in the sodium alginate solution. The mass concentration of the calcium chloride saturated borax solution is 1wt%~5wt%.

2. The self-healing inhibitor according to claim 1, characterized in that, The mass ratio of the gelatin to the sodium alginate solution is 1:

2.

3. The self-healing inhibitor according to claim 1, characterized in that, The mass ratio of polyvinyl alcohol to sodium alginate in the sodium alginate solution is 1:

2.

4. The self-healing inhibitor according to claim 1, characterized in that, The mass of the plasticizer is 20-40 wt% of the total mass of sodium alginate, gelatin and polyvinyl alcohol in the sodium alginate solution.

5. The self-healing inhibitor according to claim 1, characterized in that, The mass concentration of the calcium chloride saturated borax solution is 2wt%~4wt%.

6. The application of the self-healing inhibitor for inhibiting spontaneous combustion of coal according to any one of claims 1 to 5 in inhibiting spontaneous combustion of coal, comprising the following steps: (1) Mix the gel-based liquid with coal to obtain a coal sample; (2) Spray the crosslinking agent onto the surface of the coal sample obtained in step (1).

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