Multi-layer microcapsules for inhibiting coal spontaneous combustion with dual-core temperature sensitivity, preparation method and device thereof

Abstract

The present invention belongs to the technical field of fire prevention and extinguishing materials for coal gob areas, and discloses a multi-layer microcapsule for inhibiting coal spontaneous combustion with dual-core temperature sensitivity, and a preparation method and device thereof. The multi-layer microcapsule includes an outer shell formed by an oil-phase low-order temperature-sensitive wall material, a first temperature-sensitive inhibition sphere and a second temperature-sensitive inhibition sphere; the first temperature-sensitive inhibition sphere includes a first inner shell formed by an oil-phase high-order temperature-sensitive wall material and a liquid-phase acidic core material; the second temperature-sensitive inhibition sphere includes a second inner shell formed by an oil-phase high-order temperature-sensitive wall material and a liquid-phase alkaline core material; a liquid-phase inhibitor core material is filled between the first inner shell, the second inner shell and the outer shell. The multi-layer microcapsule of the present invention can inhibit coal spontaneous combustion in a hierarchical and staged manner at different critical temperature sections of low-temperature oxidation of coal, thereby improving the inhibition efficiency and inhibition effect of coal spontaneous combustion, and finally realizing the collaborative prevention and control of coal spontaneous combustion by "inerting - inhibiting".

Description

Technical Field

[0001] The present invention relates to the technical field of fire prevention and extinguishing materials for coal mined - out areas, and particularly to a multi - layer microcapsule with dual - core temperature - sensitive inhibition of coal spontaneous combustion, and a preparation method and device thereof. Background Art

[0002] During the coal mining process, coal spontaneous combustion is one of the main types of coal mine safety accidents. The fire source of coal spontaneous combustion directly or indirectly causes disaster accidents such as mine fires, gas - dust explosions, etc., resulting in casualties and waste of coal resources, restricting the safe production and sustainable development of coal mines. Therefore, researching and developing efficient and new coal spontaneous combustion prevention and control materials is of great significance for coal mine safety production.

[0003] In order to reduce the risk of coal spontaneous combustion disasters, current prevention and control methods for coal spontaneous combustion include grouting, inert gas, gel, spraying inhibitor, and spraying foam, etc. Among them, due to the advantages of significant fire prevention effect, convenient operation, and little environmental impact, inhibitors have become the most commonly used technology for suppressing coal spontaneous combustion fires at present. However, traditional inhibitors have deficiencies such as being easily oxidized, decomposed by heat, and short action time, resulting in the weakening or even failure of the inhibitor effect in advance.

[0004] To solve the defects of the above - mentioned traditional inhibitors, those skilled in the art have proposed microencapsulation technology. For example, the prior art CN111287786A proposes a temperature - sensitive bursting coating inhibitor. In this prior art, a reaction material is injected into the drilled holes of the coating shell and wrapped with paraffin. When the coal temperature reaches the critical temperature, the paraffin melts and the reactants generate inert gas, reducing the oxygen concentration and inhibiting coal spontaneous combustion. And the prior art CN108729943A proposes a temperature - sensitive microcapsule with catechin, ascorbic acid, anthocyanin and other antioxidants as the core material and polyethylene glycol as the wall material. When the coal temperature rises to the melting point of the coating layer, the wall material is heated and melted to release the core material, avoiding premature inactivation of the antioxidant, prolonging the inhibition timeliness, and improving the inhibition efficiency. Although the above - mentioned several prior arts isolate the inhibitor from the external environment through microencapsulation technology, and achieve response and targeted release at a certain critical temperature of coal spontaneous combustion, improving the inhibition efficiency and prolonging the inhibition life. However, as the coal mining location deepens continuously, there is a problem that the volume of the temperature - sensitive material of the coating is too large to penetrate into the deep coal and rock in the mined - out area to achieve rapid response to inhibit coal spontaneous combustion. At the same time, the time for the coal body at different coal and rock depths to reach the critical temperature point is also different, and it is difficult for a single - layer microcapsule to rapidly respond and release the inhibitor in stages according to different critical temperature points. Summary of the Invention

[0005] To solve the above technical problems, the present invention provides a multi-layer microcapsule for inhibiting coal spontaneous combustion with dual-core temperature sensitivity, and a preparation method and device thereof. The multi-layer microcapsule of the present invention can penetrate deep into coal and rock fissures and release inhibitors in stages at different stages of coal oxidation and spontaneous combustion. During the use of the multi-layer microcapsule of the present invention, when the coal temperature rises to the low-order critical temperature point, the outermost temperature-sensitive wall material is heated and melted to release the core material to chemically inhibit coal spontaneous combustion, and at the same time, dual-core temperature-sensitive inhibitor spheres are released: the first temperature-sensitive inhibitor sphere and the second temperature-sensitive inhibitor sphere. When the coal temperature continues to rise to the high-order critical temperature point, the wall materials of the dual-core temperature-sensitive inhibitor spheres are heated and melted to release an acidic salt solution and a bicarbonate solution to further achieve the effect of chemically inhibiting coal, and at the same time, a large amount of carbon dioxide inert gas is generated by the reaction between the released acidic salt solution and bicarbonate solution, reducing the oxygen concentration, so as to achieve the effect of physically and chemically compound inhibiting coal spontaneous combustion in layers and in stages at different critical temperature points.

[0006] The multi-layer microcapsule for inhibiting coal spontaneous combustion with dual-core temperature sensitivity, and the preparation method and device thereof of the present invention are realized through the following technical solutions:

[0007] To solve the problem that single-layer microcapsules are difficult to quickly respond and release inhibitors in stages at different critical temperature points, the present invention proposed at the initial stage of exploration to form microcapsules with a multi-layer structure arranged concentrically as shown in Figure 1 to meet the requirement of quickly responding and releasing in stages at different critical temperature points. However, in the subsequent exploration process of the present invention, it was found that although the microcapsules with a multi-layer structure of concentric structure achieve the effect of inhibiting coal body through the way of layer-by-layer release, the core material inhibitor released by each layer is a single type of inhibitor, and its inhibition function is single, and the inhibition effect on the coal body needs to be improved. In order to realize a composite inhibitor material that can prevent coal spontaneous combustion in layers and in stages at different critical temperature points and finally achieve the effect of physically and chemically synergistically preventing coal spontaneous combustion, the present invention provides a multi-layer microcapsule for inhibiting coal spontaneous combustion with dual-core temperature sensitivity, and the multi-layer microcapsule of the present invention includes an outer shell, and the first temperature-sensitive inhibitor sphere and the second temperature-sensitive inhibitor sphere distributed inside the outer shell.

[0008] In the present invention, the first temperature-sensitive inhibitor pellet includes a first inner shell, and a liquid-phase acidic core material encapsulated within the first inner shell. The second temperature-sensitive inhibitor pellet includes a second inner shell, and a liquid-phase alkaline core material encapsulated within the second inner shell. Moreover, in the present invention, a liquid-phase inhibitor core material is filled between the first inner shell, the second inner shell and the outer shell. Based on the above, the present invention provides a dual-core temperature-sensitive inhibitor pellet, namely the first temperature-sensitive inhibitor pellet and the second temperature-sensitive inhibitor pellet. By encapsulating a liquid-phase acidic core material within the first temperature-sensitive inhibitor pellet and a liquid-phase alkaline core material within the second temperature-sensitive inhibitor pellet respectively, the inhibitor core materials filled within the dual-core temperature-sensitive inhibitor pellet and the liquid-phase inhibitor core material are different inhibitor core materials with different inhibition functions.

[0009] Moreover, the outer shell of the present invention is formed by an oil-phase low-order temperature-sensitive wall material; both the first inner shell and the second inner shell are formed by an oil-phase high-order temperature-sensitive wall material. That is, the multi-layer microcapsule provided by the present invention is a four-layer temperature-sensitive microcapsule containing the first temperature-sensitive inhibitor pellet and the second temperature-sensitive inhibitor pellet. When the multi-layer microcapsule of the present invention is used, when the temperature of the surrounding environment reaches the low-order critical temperature point, the outer shell is heated and melted, releasing the liquid-phase inhibitor core material. Since the liquid-phase inhibitor core material is an antioxidant solution or an ionic liquid, the liquid-phase inhibitor core material can capture the free radicals generated by coal oxidation, generate stable intermediate products, block the coal oxidation chain reaction process, and play an effect of chemically inhibiting coal spontaneous combustion. At the same time, when chemically inhibiting the coal body, the dual-core temperature-sensitive inhibitor pellet, namely the first temperature-sensitive inhibitor pellet and the second temperature-sensitive inhibitor pellet, will be released. If the initial chemical inhibition of the coal body by the liquid-phase inhibitor core material fails over time and the coal oxidation continues to heat up to the high-order critical temperature point, the oil-phase high-order temperature-sensitive wall materials of the first temperature-sensitive inhibitor pellet and the second temperature-sensitive inhibitor pellet are heated and melted, simultaneously releasing the liquid-phase acidic core material and the liquid-phase alkaline core material. The released liquid-phase acidic core material and liquid-phase alkaline core material will act on different coal oxidation free radicals when chemically inhibiting the coal body and generate different stable groups. In addition, a large amount of inert gas CO2 will be generated by the reaction between the liquid-phase acidic core material and the liquid-phase alkaline core material to displace the O2 in the coal pores, thereby reducing the spontaneous combustion of coal in an oxygen environment; and as the temperature increases, the reaction rate accelerates, resulting in more generated inert gas CO2, ultimately achieving the combined physical and chemical prevention and control of coal spontaneous combustion.

[0010] In some preferred embodiments of the present invention, the oil-phase low-order temperature-sensitive wall material is made of a temperature-sensitive material, a flame retardant material and a strengthening material; wherein, based on the strengthening material, the addition amount of the temperature-sensitive material is 6.5 to 7.5 times the mass of the strengthening material; the addition amount of the flame retardant material is 1.5 to 2.5 times the mass of the strengthening material.

[0011] In some preferred embodiments of the present invention, the temperature-sensitive material is one or more of chlorinated paraffin, polyethylene glycol, and polyvinyl chloride.

[0012] Among them, in some more preferred embodiments of the present invention, the chlorinated paraffin is one or more of 30# chlorinated paraffin to 50# chlorinated paraffin.

[0013] In some more preferred embodiments of the present invention, the flame retardant material is one or more of ammonium polyphosphate, zinc borate hydrate, and aluminum hydroxide.

[0014] In some more preferred embodiments of the present invention, the strengthening material is one or more of diatomite, montmorillonite, polyacrylamide, and glass fiber.

[0015] In some preferred embodiments of the present invention, the oil-phase high-order temperature-sensitive wall material is one or more of 50# chlorinated paraffin to 90# chlorinated paraffin.

[0016] In some preferred embodiments of the present invention, the antioxidant solution is prepared from an antioxidant and water; the mass fraction of the antioxidant in the antioxidant solution is 40% to 70%.

[0017] In some more preferred embodiments of the present invention, the antioxidant is one or more of rosmarinic acid, tea polyphenols, procyanidins, and vitamin C.

[0018] In some preferred embodiments of the present invention, the ionic liquid is an imidazole-based ionic liquid. Among them, in some more preferred embodiments of the present invention, the imidazole-based ionic liquid is one or more of 1-butyl-3-methylimidazolium nitrate, 1-butyl-3-methylimidazolium iodide, 1-ethyl-3-methylimidazolium tetrafluoroborate, and 1-butyl-3-methylimidazolium tetrafluoroborate. For the sake of convenience of expression, 1-butyl-3-methylimidazolium nitrate is abbreviated as [BMIM][NO3], 1-butyl-3-methylimidazolium iodide is abbreviated as [BMIM][I], 1-ethyl-3-methylimidazolium tetrafluoroborate is abbreviated as [EMIM][BF4], and 1-butyl-3-methylimidazolium tetrafluoroborate is abbreviated as [BMIM][BF4].

[0019] In some preferred embodiments of the present invention, the liquid-phase acidic core material is an acidic salt aqueous solution. Among them, the acidic salt aqueous solution is a phosphate solution or an acetate solution.

[0020] In some preferred embodiments of the present invention, when the acidic salt aqueous solution is a phosphate solution, the mass concentration of the phosphate aqueous solution is 15% to 20%. Among them, in some more preferred embodiments of the present invention, the phosphate used in the phosphate solution can be selected from trisodium phosphate.

[0021] In some preferred embodiments of the present invention, when the acidic brine solution is an acetate solution, the mass concentration of the acetate solution is 10% to 30%. Among them, in some more preferred embodiments of the present invention, the acetate used in the acetate solution may be selected from sodium acetate.

[0022] In some preferred embodiments of the present invention, the liquid-phase alkaline core material is an aqueous bicarbonate solution. Among them, the aqueous bicarbonate solution is an aqueous sodium bicarbonate solution. In some more preferred embodiments of the present invention, the mass concentration of the aqueous bicarbonate solution is 10% to 20%.

[0023] The present invention also provides a method for preparing the multi-layer microcapsule for dual-core temperature-sensitive inhibition of coal spontaneous combustion as described above, comprising the following steps:

[0024] Step 1, prepare the preparation device:

[0025] 1.1) Prepare a cooling device, a first double-channel liquid injection tube, a second double-channel liquid injection tube, and a third double-channel liquid injection tube with the same structure.

[0026] It should be noted that the first double-channel liquid injection tube, the second double-channel liquid injection tube, and the third double-channel liquid injection tube used in the present invention all include an inner tube and an outer tube arranged coaxially; among them, the inner tube has a hollow structure to serve as an inner-phase component delivery channel for delivering inner-phase components, and there is a gap between the outer wall of the inner tube and the outer tube to form an outer-phase component delivery channel for delivering outer-phase components.

[0027] 1.2) Vertically arrange the first double-channel liquid injection tube, the second double-channel liquid injection tube, and the third double-channel liquid injection tube, and make the first double-channel liquid injection tube and the second double-channel liquid injection tube at the same horizontal height, and the third double-channel liquid injection tube is located below the first double-channel liquid injection tube and the second double-channel liquid injection tube, and the cooling device is located directly below the output end of the third double-channel liquid injection tube; and respectively connect the output ends of the first double-channel liquid injection tube and the second double-channel liquid injection tube to the input end of the inner-phase component delivery channel in the third double-channel liquid injection tube through a fluid distribution array.

[0028] It should be noted that by making the first double-channel liquid injection tube and the second double-channel liquid injection tube at the same horizontal height, they are respectively used to prepare the first temperature-sensitive inhibition ball and the second temperature-sensitive inhibition ball.

[0029] It should also be noted that the third double-channel liquid injection tube is directly below the middle position between the first double-channel liquid injection tube and the second double-channel liquid injection tube, and the cooling device is arranged directly below the output end of the third double-channel liquid injection tube, so that the first composite-phase droplet ball corresponding to the first temperature-sensitive inhibitor ball and the second composite-phase droplet ball corresponding to the second temperature-sensitive inhibitor ball can be simultaneously transported into the inner-phase component transport channel of the double-channel liquid injection tube below, so as to facilitate the first composite-phase droplet ball, the second composite-phase droplet ball and the liquid-phase inhibitor core material to be uniformly wrapped by the molten oil-phase low-temperature-sensitive wall material to form a third composite-phase droplet. Finally, the third composite-phase droplet enters the cooling device to be cooled and solidified to obtain the multi-layer microcapsule.

[0030] Step 2, Preparation of the first temperature-sensitive inhibitor ball:

[0031] Taking the liquid-phase acidic core material as the inner-phase component, melting the oil-phase high-temperature-sensitive wall material into a molten oil-phase high-temperature-sensitive wall material and taking it as the outer-phase component, and injecting them into the corresponding transport channels of the first double-channel liquid injection tube respectively. Under the combined action of shear force and surface tension, the inner-phase component uniformly wraps a layer of molten oil-phase high-temperature-sensitive wall material on the surface of a single liquid-phase acidic core material droplet to form a first composite-phase droplet ball corresponding to the first temperature-sensitive inhibitor ball.

[0032] Step 3, Preparation of the second temperature-sensitive inhibitor ball:

[0033] Taking the liquid-phase alkaline core material as the inner-phase component, melting the oil-phase high-temperature-sensitive wall material to obtain a molten oil-phase high-temperature-sensitive wall material as the outer-phase component, and injecting them into the corresponding transport channels of the second double-channel liquid injection tube respectively. Under the combined action of shear force and surface tension, the inner-phase component uniformly wraps a layer of molten oil-phase high-temperature-sensitive wall material on the surface of a single liquid-phase alkaline core material droplet to form a second composite-phase droplet ball corresponding to the second temperature-sensitive inhibitor ball.

[0034] Step 4, Formation of multi-layer microcapsules:

[0035] Taking the first composite-phase droplet ball, the second composite-phase droplet ball and the liquid-phase inhibitor core material together as the inner-phase component, melting the oil-phase low-temperature-sensitive wall material to obtain a molten oil-phase low-temperature-sensitive wall material as the outer-phase component, and injecting them into the corresponding transport channels of the third double-channel liquid injection tube respectively. Under the combined action of shear force and surface tension, the inner-phase component forms third composite-phase droplet balls with the same size and different solutions wrapped in a single droplet; subsequently, the third composite-phase droplet balls fall into the cooling device to be cooled and solidified to obtain the multi-layer microcapsules.

[0036] The present invention also provides a preparation device for the above-mentioned preparation method to realize the preparation of multi-layer microcapsules for inhibiting coal spontaneous combustion with dual-core temperature sensitivity through the preparation device. The preparation device of the present invention includes a fluid distribution table, a first double-channel liquid injection pipe, a second double-channel liquid injection pipe, a third double-channel liquid injection pipe, two fluid distribution arrays, and a cooling device.

[0037] In the present invention, three mounting seats are sequentially arranged on the fluid distribution table. Among the three mounting seats, one mounting seat is arranged in the middle of the lower end of the fluid distribution table, and the other two mounting seats are respectively arranged on both sides of the upper end of the fluid distribution table.

[0038] In the present invention, the first double-channel liquid injection pipe and the second double-channel liquid injection pipe are respectively vertically installed on the two mounting seats at the upper end of the fluid distribution table; the third double-channel liquid injection pipe is installed on the mounting seat at the lower end of the fluid distribution table.

[0039] In the present invention, the input end of the cooling device is directly below the output end of the third double-channel liquid injection pipe.

[0040] In the present invention, the first double-channel liquid injection pipe, the second double-channel liquid injection pipe, and the third double-channel liquid injection pipe have the same structure, and each includes an inner pipe and an outer pipe arranged coaxially. The inner pipe has a hollow structure to serve as an inner-phase component delivery channel for delivering inner-phase components. There is a gap between the outer wall of the inner pipe and the outer pipe to form an outer-phase component delivery channel for delivering outer-phase components.

[0041] One of the fluid distribution arrays is arranged between the output end of the first double-channel liquid injection pipe and the input end of the inner-phase component delivery channel of the third double-channel liquid injection pipe, and the other fluid distribution array is arranged between the output end of the second double-channel liquid injection pipe and the input end of the inner-phase component delivery channel of the third double-channel liquid injection pipe.

[0042] In some preferred embodiments of the present invention, the mounting bracket is used to install and fix the positions of the fluid distribution table, the first double-channel liquid injection pipe, the second double-channel liquid injection pipe, the third double-channel liquid injection pipe, the two fluid distribution arrays, and the cooling device. In some more preferred embodiments of the present invention, the fluid distribution table is arranged at the upper end of the mounting bracket, and the cooling device is arranged at the bottom of the mounting bracket.

[0043] In some preferred embodiments of the present invention, the cooling device adopted is a liquid-receiving cooling tray, and deionized water is placed in the liquid-receiving cooling tray.

[0044] Compared with the prior art, the present invention has the following beneficial effects:

[0045] The multi-layer microcapsule for dual-core temperature-sensitive inhibition of coal spontaneous combustion according to the present invention includes an outer shell, and a first temperature-sensitive inhibition sphere and a second temperature-sensitive inhibition sphere distributed inside the outer shell. Among them, the first temperature-sensitive inhibition sphere includes a first inner shell, and a liquid-phase acidic core material wrapped inside the first inner shell. The second temperature-sensitive inhibition sphere includes a second inner shell, and a liquid-phase alkaline core material wrapped inside the second inner shell. Moreover, the outer wall of the first inner shell and the outer wall of the second inner shell do not contact the inner wall of the outer shell, so as to form a first cavity; a liquid-phase inhibitor core material is filled in the first cavity. That is, the multi-layer microcapsule provided by the present invention is a four-layer temperature-sensitive microcapsule containing dual-core temperature-sensitive inhibition spheres of the first temperature-sensitive inhibition sphere and the second temperature-sensitive inhibition sphere. When the multi-layer microcapsule of the present invention is used, when the temperature of the surrounding environment reaches the low-order critical temperature point, the outer shell is heated and melted, and the liquid-phase inhibitor core material is released. Since the liquid-phase inhibitor core material is one or more of an antioxidant solution or an ionic liquid, the liquid-phase inhibitor core material can block or inhibit the process of the coal oxidation chain reaction, and play the role of chemically inhibiting coal spontaneous combustion. And at the same time of chemically inhibiting the coal body, dual-core temperature-sensitive inhibition spheres will be released, that is, the first temperature-sensitive inhibition sphere and the second temperature-sensitive inhibition sphere. If the initial inhibition of the coal body by the liquid-phase inhibitor core material fails over time and the coal oxidation continues to rise to the high-order critical temperature point, the oil-phase high-order temperature-sensitive wall materials of the first temperature-sensitive inhibition sphere and the second temperature-sensitive inhibition sphere are heated and melted, and at the same time the liquid-phase acidic core material and the liquid-phase alkaline core material are released. The released liquid-phase acidic core material and liquid-phase alkaline core material will act on different coal oxidation free radicals when chemically inhibiting the coal body, and generate different stable groups, so as to achieve hierarchical and staged inhibition at different critical temperature segments of coal low-temperature oxidation, and then improve the inhibition efficiency and inhibition effect of coal spontaneous combustion. In addition, a reaction will occur between the liquid-phase acidic core material and the liquid-phase alkaline core material to generate a large amount of inert gas CO2 to displace O2 in the coal pores, thereby reducing the spontaneous combustion of coal in an oxygen environment; and as the temperature rises, the reaction rate accelerates, so that more inert gas CO2 is generated, and the competitive adsorption effect with oxygen is stronger, thus realizing the physical and chemical synergistic prevention and control of coal spontaneous combustion of "inerting-inhibiting".

[0046] The multi-layer microcapsule for dual-core temperature-sensitive inhibition of coal spontaneous combustion according to the present invention has a micron-level size and can penetrate deep coal-rock fractures to inhibit the coal body. In addition, the structural setting of the multi-layer microcapsule of the present invention can effectively avoid the occurrence of situations such as the oxidation, thermal decomposition and short action time of the inhibitor core material, extend the inhibition timeliness, and improve the inhibition efficiency.

[0047] The raw materials used in the dual-core temperature-sensitive coal spontaneous combustion inhibitor multi-layer microcapsules of the present invention are widely sourced, environmentally friendly, non-toxic, harmless, and low in cost. Different core materials of the multi-layer microcapsules of the present invention have different degrees of physical or chemical inhibition effects on coal bodies. The wall materials of the multi-layer microcapsules of the present invention can achieve different melting temperatures by regulating the components and their ratios. At the same time, flame retardant materials and reinforcing materials are added to the low-order temperature-sensitive wall materials in the oil phase to improve the stability and mechanical properties of the multi-layer microcapsules.

[0048] The present invention designs a preparation device using microfluidic technology. By selecting the types of core materials and wall materials, and designing the coaxial double-channel liquid injection tube and fluid distribution array, dual-core multi-layer microcapsules can be rapidly synthesized and prepared. Aiming at the drawbacks of the existing microcapsule preparation process, the designed microfluidic system device has a highly integrated structure and is easy to operate, greatly improving the core material coating rate of the microcapsules, effectively reducing energy consumption and material consumption, and being able to efficiently prepare multi-layer microcapsules with uniform particle size, easily controllable functional properties, and stable morphology, thus providing a new prevention and control measure for ensuring coal mine safety. Brief Description of the Drawings

[0049] Figure 1 Schematic structural diagram of the coaxial multi-layer microcapsules prepared in Comparative Example 1; Figure 1 In it, B is the outermost shell formed by the low-order temperature-sensitive wall material in the oil phase, B1 is the inner shell formed by the high-order temperature-sensitive wall material in the oil phase, X is the outer inhibitor core material, and X1 is the inner inhibitor core material.

[0050] Figure 2 Schematic structural diagram of the multi-layer microcapsules of the present invention; Figure 2 In it, B is the outer shell, X is the liquid-phase inhibitor core material, Q1 is the first temperature-sensitive inhibitor sphere, Q2 is the second temperature-sensitive inhibitor sphere, B1 is the first inner shell, B2 is the second inner shell, X1 is the liquid-phase acidic core material, and X2 is the liquid-phase alkaline core material.

[0051] Figure 3 Schematic diagram of the inhibition mechanism of the multi-layer microcapsules of the present invention.

[0052] Figure 4 Main preparation flow chart of the multi-layer microcapsules of the present invention.

[0053] Figure 5 Schematic structural diagram of the preparation device of the present invention. Detailed Description of the Embodiments

[0054] The technical solutions in the embodiments of the present invention will be clearly and completely described below.

[0055] Example 1

[0056] Please refer to Figure 2, this embodiment provides a multi-layer microcapsule for dual-core temperature-sensitive inhibition of coal spontaneous combustion. The multi-layer microcapsule of this embodiment includes an outer shell B, and a first temperature-sensitive inhibition sphere Q1 and a second temperature-sensitive inhibition sphere Q2 distributed inside the outer shell. Among them, the first temperature-sensitive inhibition sphere Q1 includes a first inner shell B1, and a liquid-phase acidic core material X1 wrapped inside the first inner shell B1. The second temperature-sensitive inhibition sphere Q2 includes a second inner shell B2, and a liquid-phase alkaline core material X2 wrapped inside the second inner shell B2; among them, the first inner shell B1, the second inner shell B2 and the outer shell B do not contact each other to form a cavity structure, and the cavity structure is filled with a liquid-phase inhibitor core material X.

[0057] It should be noted that the multi-layer microcapsule for dual-core temperature-sensitive inhibition of coal spontaneous combustion provided in this embodiment is for spontaneous combustion coal seams under uneven temperatures, and the total number of layers is set to four.

[0058] In the four-layer structure of the multi-layer microcapsule of this embodiment, the first layer from the outside to the inside is the outer shell B. The outer shell B in this embodiment is formed by an oil-phase low-order temperature-sensitive wall material, and the oil-phase low-order temperature-sensitive wall material in this embodiment is formed by mixing 40# chlorinated paraffin, ammonium polyphosphate and glass fiber. The addition amount of 40# chlorinated paraffin is 7 times the mass of the glass fiber, and the addition amount of ammonium polyphosphate is 2 times the mass of the glass fiber, so that the melting point of the outer shell B in this embodiment is about 40°C.

[0059] The second layer is the liquid-phase inhibitor core material X provided between the first temperature-sensitive inhibition sphere Q1, the second temperature-sensitive inhibition sphere Q2 and the outer shell B. The liquid-phase inhibitor core material X in this embodiment is a tea polyphenol aqueous solution with a mass fraction of 70%.

[0060] The third layer is the first inner shell B1 in the first temperature-sensitive inhibition sphere Q1 and the second inner shell B2 in the second temperature-sensitive inhibition sphere Q2. In this embodiment, both the first inner shell B1 and the second inner shell B2 are 70# chlorinated paraffin, so that the melting points of the first inner shell B1 and the second inner shell B2 in this embodiment are both about 70°C.

[0061] The fourth layer is the liquid-phase acidic core material X1 wrapped inside the first inner shell B1 and the liquid-phase alkaline core material X2 wrapped inside the second inner shell B2. In this embodiment, the liquid-phase acidic core material X1 is a phosphate solution with a mass concentration of 18%, and the liquid-phase alkaline core material X2 is a sodium bicarbonate solution with a mass concentration of 15%.

[0062] Based on the above, the multi-layer microcapsule of this embodiment is a four-layer temperature-sensitive microcapsule containing a first temperature-sensitive inhibition sphere and a second temperature-sensitive inhibition sphere, so that the multi-layer microcapsule of the present invention can effectively prevent and control coal spontaneous combustion through the step-by-step release of the materials from the first layer to the fourth layer. Specifically, please refer toFigure 3 When the multi-layer microcapsules of this embodiment are used for preventing and controlling coal spontaneous combustion, when the coal temperature rises to around the low-order critical temperature point of 40 °C, the first-layer material of the multi-layer microcapsules of this embodiment, that is, the outer shell B, is heated and melted, thereby releasing the second-layer material, namely the liquid-phase inhibitor core material X, and at the same time releasing the dual-core high-temperature-sensitive inhibitor small balls, namely the first temperature-sensitive inhibitor small ball Q1 and the second temperature-sensitive inhibitor small ball Q2. The liquid-phase inhibitor core material X is a tea polyphenol solution, so that a thin film can be formed on the coal surface, achieving the effect of wetting the coal body and physically inhibiting coal spontaneous combustion. At the same time, the tea polyphenol solution captures free radicals in the coal through chemical reactions, generates stable intermediate products, and blocks the process of the coal oxidation chain reaction, achieving the effect of chemically inhibiting coal spontaneous combustion. If the preliminary physical and chemical inhibition of the tea polyphenol solution fails over time and the coal temperature rises to 70 °C, the third-layer material of the multi-layer microcapsules of this embodiment, that is, the first inner shell B1 in the first temperature-sensitive inhibitor small ball Q1 and the second inner shell B2 in the second temperature-sensitive inhibitor small ball Q2, are heated and melted, and at the same time release the fourth-layer material, namely the phosphate solution as the liquid-phase acidic core material X1 and the sodium bicarbonate solution as the liquid-phase alkaline core material X2. Among them, the phosphate solution as the liquid-phase acidic core material X1 achieves the effect of chemically inhibiting coal spontaneous combustion by inhibiting the generation of hydroxyl free radicals in the coal and promoting the formation of stable saturated ether bonds. At the same time, the phosphate solution as the liquid-phase acidic core material X1 can also react with the sodium bicarbonate solution of the liquid-phase alkaline core material X2 to generate a large amount of inert gas CO2, displace O2 in the coal pores, and physically inhibit coal spontaneous combustion, ultimately realizing the function of physically and chemically compounding and inhibiting coal spontaneous combustion at different critical temperature points in a hierarchical and staged manner.

[0063] It should also be noted that when the phosphate solution is in excess, the reaction equation of the phosphate solution of the liquid-phase acidic core material X1 and the sodium bicarbonate solution of the liquid-phase alkaline core material X2 is shown in Equation 1.

[0064] NaHCO3 + H3PO4 → NaH2PO4 + H2O + CO2↑ Equation 1.

[0065] When the sodium bicarbonate solution is in excess, the reaction equation of the phosphate solution of the liquid-phase acidic core material X1 and the sodium bicarbonate solution of the liquid-phase alkaline core material X2 is shown in Equation 2.

[0066] 2NaHCO3 + H3PO4 → Na_{2}HPO4 + 2H2O + 2CO2↑ Equation 2.

[0067] Please refer to Figure 4 , the preparation method of the multi-layer microcapsules of this embodiment includes the following steps:

[0068] Step 1, prepare the preparation device:

[0069] 1.1) Prepare a cooling device, as well as a first double-channel liquid injection tube 1, a second double-channel liquid injection tube 2, and a third double-channel liquid injection tube 3 with the same structure. The first double-channel liquid injection tube 1, the second double-channel liquid injection tube 2, and the third double-channel liquid injection tube 3 all include an inner tube 4 and an outer tube 5 arranged coaxially. The inner tube 4 serves as the inner-phase component delivery channel, and the gap between the outer wall of the inner tube 4 and the outer tube 5 serves as the outer-phase component delivery channel.

[0070] 1.2) Vertically arrange the first double-channel liquid injection tube 1, the second double-channel liquid injection tube 2, and the third double-channel liquid injection tube 3, and make the first double-channel liquid injection tube 1 and the second double-channel liquid injection tube 2 at the same horizontal height. The third double-channel liquid injection tube 3 is located below the first double-channel liquid injection tube 1 and the second double-channel liquid injection tube 2. The cooling device is located directly below the output end of the third double-channel liquid injection tube 3. And respectively connect the output ends of the first double-channel liquid injection tube 1 and the second double-channel liquid injection tube 2 to the input end of the inner-phase component delivery channel in the third double-channel liquid injection tube 3 through a fluid distribution array 8.

[0071] Step 2, Preparation of the first temperature-sensitive inhibitor microsphere Q1:

[0072] 2.1) Fully dissolve trisodium phosphate in deionized water to obtain an aqueous phosphate solution with a mass concentration of 18%, which serves as the liquid-phase acidic core material.

[0073] 2.2) Heat 70# chlorinated paraffin to the molten state at a temperature of 70 °C to obtain a molten liquid of the oil-phase high-order temperature-sensitive wall material.

[0074] 2.3) Inject the liquid-phase acidic core material into the inner-phase component delivery channel of the first double-channel liquid injection tube 1, and inject the molten liquid of the oil-phase high-order temperature-sensitive wall material into the outer-phase component delivery channel of the first double-channel liquid injection tube 1. Since the inner tube 4 and the outer tube 5 are arranged coaxially, the inner-phase component is uniformly coated with a layer of molten liquid of the oil-phase high-order temperature-sensitive wall material on the surface of each single liquid-phase acidic core material droplet of the inner-phase component under the combined action of shear force and surface tension, forming the first composite-phase droplet microsphere corresponding to the first temperature-sensitive inhibitor microsphere Q1.

[0075] Step 3, Preparation of the second temperature-sensitive inhibitor microsphere:

[0076] 3.1) Fully dissolve sodium bicarbonate in deionized water to obtain a liquid-phase basic core material with a mass concentration of 15%.

[0077] 3.2) Heat 70# chlorinated paraffin to the molten state at a temperature of 70 °C to obtain a molten liquid of the oil-phase high-order temperature-sensitive wall material.

[0078] 3.3) Inject the liquid-phase alkaline core material prepared in step 3.1) into the inner-phase component delivery channel of the second double-channel liquid injection tube 2, and inject the molten oil-phase high-order temperature-sensitive wall material into the outer-phase component delivery channel of the second double-channel liquid injection tube 2. Since the inner tube 4 and the outer tube 5 are coaxially arranged, the inner-phase component is uniformly coated with a layer of molten oil-phase high-order temperature-sensitive wall material on the surface of each single liquid-phase alkaline core material droplet of the inner-phase component under the combined action of shear force and surface tension, forming the second composite-phase droplet sphere corresponding to the second temperature-sensitive inhibitor sphere Q2.

[0079] It should be emphasized that the above steps 2.2) and 3.3) are carried out synchronously.

[0080] Step 4, forming multi-layer microcapsules:

[0081] 4.1) Disperse tea polyphenols in deionized water to form a tea polyphenol aqueous solution with a mass fraction of 70% as the liquid-phase inhibitor core material.

[0082] 4.2) Mix 40# chlorinated paraffin, ammonium polyphosphate, and glass fiber according to the above ratio, and heat them to the molten state at a temperature of 70 °C to obtain the molten oil-phase low-order temperature-sensitive wall material.

[0083] 4.3) Use the first composite-phase droplet sphere obtained in step 2.2), the second temperature-sensitive inhibitor sphere obtained in step 3.3), and the liquid-phase inhibitor core material prepared in 4.1) above as the inner-phase component, and use the molten oil-phase low-order temperature-sensitive wall material prepared in step 4.2) as the outer-phase component. Inject the inner-phase component into the inner-phase component delivery channel of the third double-channel liquid injection tube 3, and inject the molten oil-phase low-order temperature-sensitive wall material into the outer-phase component delivery channel of the third double-channel liquid injection tube 3. Since the inner tube 4 and the outer tube 5 are coaxially arranged, the inner-phase component is uniformly coated with a layer of molten oil-phase low-order temperature-sensitive wall material on the surface of each single droplet of the inner-phase component under the combined action of shear force and surface tension, forming the third composite-phase droplet sphere. The composite-phase droplet sphere falls into the cooling device 9 below it for cooling treatment until the outermost layer of the molten oil-phase low-order temperature-sensitive wall material of the third composite-phase droplet sphere cools and solidifies to form an outer shell, and then undergoes filtration treatment to obtain the multi-layer microcapsules of this embodiment.

[0084] Example 2

[0085] This embodiment provides a multi-layer microcapsule for dual-core temperature-sensitive inhibition of coal spontaneous combustion.

[0086] Please refer to Figure 2 , it can be seen that for the spontaneous combustion coal seam under uneven temperature, the total number of layers of the multi-layer microcapsule for dual-core temperature-sensitive inhibition of coal spontaneous combustion provided in this embodiment is four layers.

[0087] In the multi-layer microcapsules of this embodiment, the first layer from the outside to the inside is the outer shell B. The outer shell B in this embodiment is formed by an oil-phase low-order temperature-sensitive wall material, and the oil-phase low-order temperature-sensitive wall material in this embodiment is formed by mixing 50# chlorinated paraffin, zinc borate hydrate and diatomaceous earth. The addition amount of 50# chlorinated paraffin is 7 times the mass of the diatomaceous earth, and the addition amount of zinc borate hydrate is 2 times the mass of the diatomaceous earth, so that the melting point of the outer shell B in this embodiment is about 50 °C.

[0088] The second layer is the liquid-phase inhibitor core material X disposed between the first temperature-sensitive inhibitor sphere Q1, the second temperature-sensitive inhibitor sphere Q2 and the outer shell B. The liquid-phase inhibitor core material X in this embodiment is the ionic liquid [BMIM][BF4].

[0089] The third layer is the first inner shell B1 in the first temperature-sensitive inhibitor sphere Q1 and the second inner shell B2 in the second temperature-sensitive inhibitor sphere Q2. In this embodiment, both the first inner shell B1 and the second inner shell B2 are 80# chlorinated paraffin, so that the melting points of the first inner shell B1 and the second inner shell B2 in this embodiment are both about 80 °C.

[0090] The fourth layer is the liquid-phase acidic core material X1 wrapped in the first inner shell B1 and the liquid-phase alkaline core material X2 wrapped in the second inner shell B2. In this embodiment, the liquid-phase acidic core material X1 is an acetate solution with a mass concentration of 20%, and the liquid-phase alkaline core material X2 is a sodium bicarbonate solution with a mass concentration of 15%.

[0091] Based on the above, the multi-layer microcapsules of this embodiment are four-layer thermosensitive microcapsules with dual-core thermosensitive inhibitor microspheres containing the first thermosensitive inhibitor microsphere and the second thermosensitive inhibitor microsphere. When the multi-layer microcapsules of the present invention are used, they can effectively prevent and control coal spontaneous combustion through the step-by-step release of materials from the first layer to the fourth layer. Specifically, when the multi-layer microcapsules of this embodiment are used for preventing and controlling coal spontaneous combustion, when the coal temperature rises to about the low-order critical temperature point of 50 °C, the first layer material of the multi-layer microcapsules of this embodiment, that is, the outer shell B, is heated and melted, thereby releasing the second layer material, that is, the liquid-phase inhibitor core material X, and at the same time releasing the dual-core high-order thermosensitive inhibitor microspheres, that is, the first thermosensitive inhibitor microsphere Q1 and the second thermosensitive inhibitor microsphere Q2. The liquid-phase inhibitor core material X is the ionic liquid [BMIM][BF4], which can dissolve and destroy the active groups in the coal, inhibit the process of coal oxidation reaction, and play the role of chemically inhibiting coal spontaneous combustion. If the preliminary physical and chemical inhibition of the ionic liquid [BMIM][BF4] fails over time and the coal temperature rises to 70 °C, the third layer material of the multi-layer microcapsules of this embodiment, that is, the first inner shell B1 in the first thermosensitive inhibitor microsphere Q1 and the second inner shell B2 in the second thermosensitive inhibitor microsphere Q2, are heated and melted, and at the same time release the fourth layer material, that is, the acetate solution as the liquid-phase acidic core material X1 and the sodium bicarbonate solution as the liquid-phase alkaline core material X2. Among them, the acetate solution as the liquid-phase acidic core material X1 can inhibit the generation of hydroxyl radicals in the coal and promote the formation of stable saturated ether bonds, thereby achieving the effect of chemically inhibiting coal spontaneous combustion. At the same time, the acetate solution as the liquid-phase acidic core material X1 can also react with the sodium bicarbonate solution of the liquid-phase alkaline core material X2 to generate a large amount of inert gas CO2, which can displace O2 in the coal pores and physically inhibit coal spontaneous combustion, ultimately realizing the physical and chemical composite inhibition of coal spontaneous combustion at different critical temperature points in a hierarchical and staged manner.

[0092] It should also be noted that the reaction equation of the acetate solution of the liquid-phase acidic core material X1 and the sodium bicarbonate solution of the liquid-phase alkaline core material X2 is shown in Equation 3.

[0093] CH3COOH + NaHCO3 → CH3COONa + H2O + CO2↑ Equation 3.

[0094] Please refer to Figure 4 , the preparation method of the multi-layer microcapsules of this embodiment includes the following steps:

[0095] Step 1, prepare the preparation device:

[0096] 1.1) Prepare a cooling device, a first double-channel liquid injection tube 1, a second double-channel liquid injection tube 2, and a third double-channel liquid injection tube 3 with the same structure. The first double-channel liquid injection tube 1, the second double-channel liquid injection tube 2, and the third double-channel liquid injection tube 3 each include an inner tube 4 and an outer tube 5 arranged coaxially. The inner tube 4 serves as the inner-phase component delivery channel, and the gap between the outer wall of the inner tube 4 and the outer tube 5 serves as the outer-phase component delivery channel.

[0097] 1.2) Vertically arrange the first double-channel liquid injection tube 1, the second double-channel liquid injection tube 2, and the third double-channel liquid injection tube 3, and make the first double-channel liquid injection tube 1 and the second double-channel liquid injection tube 2 at the same horizontal height. The third double-channel liquid injection tube 3 is located below the first double-channel liquid injection tube 1 and the second double-channel liquid injection tube 2. The cooling device is located directly below the output end of the third double-channel liquid injection tube 3. And respectively connect the output ends of the first double-channel liquid injection tube 1 and the second double-channel liquid injection tube 2 to the input end of the inner-phase component delivery channel in the third double-channel liquid injection tube 3 through a fluid distribution array 8.

[0098] Step 2, Preparation of the first temperature-sensitive inhibitor microsphere Q1:

[0099] 2.1) Fully dissolve sodium acetate in deionized water to obtain a liquid-phase acidic core material with a mass concentration of 20%.

[0100] 2.2) Heat 80# chlorinated paraffin to the molten state at a temperature of 70°C to obtain a molten liquid of the oil-phase high-order temperature-sensitive wall material.

[0101] 2.3) Inject the liquid-phase acidic core material into the inner-phase component delivery channel of the first double-channel liquid injection tube 1, and inject the molten liquid of the oil-phase high-order temperature-sensitive wall material into the outer-phase component delivery channel of the first double-channel liquid injection tube 1. Since the inner tube 4 and the outer tube 5 are arranged coaxially, under the combined action of shear force and surface tension of the inner-phase component and the outer-phase component, a layer of molten liquid of the oil-phase high-order temperature-sensitive wall material is evenly coated on the surface of each single liquid-phase acidic core material droplet, forming a first composite-phase liquid droplet microsphere corresponding to the first temperature-sensitive inhibitor microsphere Q1.

[0102] Step 3, Preparation of the second temperature-sensitive inhibitor microsphere:

[0103] 3.1) Fully dissolve sodium bicarbonate in deionized water to obtain a liquid-phase alkaline core material with a mass concentration of 15%.

[0104] 3.2) Heat 80# chlorinated paraffin to the molten state at a temperature of 80°C to obtain a molten liquid of the oil-phase high-order temperature-sensitive wall material.

[0105] 3.3) Inject the liquid-phase alkaline core material prepared in step 3.1) into the inner-phase component delivery channel of the second double-channel liquid injection tube 2, and inject the molten liquid of the oil-phase high-order temperature-sensitive wall material into the outer-phase component delivery channel of the second double-channel liquid injection tube 2. Since the inner tube 4 and the outer tube 5 are coaxially arranged, under the combined action of shear force and surface tension, the inner-phase component is uniformly coated with a layer of molten liquid of the oil-phase high-order temperature-sensitive wall material on the surface of a single liquid-phase alkaline core material droplet, forming a second composite-phase droplet sphere corresponding to the second temperature-sensitive inhibition sphere Q2.

[0106] It should be emphasized that the above steps 2.2) and 3.3) are carried out synchronously.

[0107] Step 4, forming multi-layer microcapsules:

[0108] 4.1) Accurately weigh the [BMIM][BF4] solution using an electronic balance as the liquid-phase inhibitor core material.

[0109] 4.2) Mix 50# chlorinated paraffin, zinc borate hydrate, and diatomite according to the above ratio, and heat them to the molten state at a temperature of 70 °C to obtain a molten liquid of the oil-phase low-order temperature-sensitive wall material.

[0110] 4.3) Use the first composite-phase droplet sphere obtained in step 2.2), the second temperature-sensitive inhibition sphere obtained in step 3.3), and the liquid-phase inhibitor core material prepared in the above 4.1) as the inner-phase components, and use the molten liquid of the oil-phase low-order temperature-sensitive wall material prepared in step 4.2) as the outer-phase component. Inject the inner-phase components into the inner-phase component delivery channel of the third double-channel liquid injection tube 3, and inject the molten liquid of the oil-phase low-order temperature-sensitive wall material into the outer-phase component delivery channel of the third double-channel liquid injection tube 3. Since the inner tube 4 and the outer tube 5 are coaxially arranged, under the combined action of shear force and surface tension, the inner-phase component is uniformly coated with a layer of molten liquid of the oil-phase low-order temperature-sensitive wall material on the surface of a single inner-phase component droplet, forming a third composite-phase droplet sphere. The composite-phase droplet sphere falls into the cooling device below for cooling treatment until the outermost layer of the molten liquid of the oil-phase low-order temperature-sensitive wall material of the third composite-phase droplet sphere cools and solidifies to form an outer shell, and then filtration treatment is carried out to obtain the multi-layer microcapsules of this embodiment.

[0111] Example 3

[0112] This embodiment provides a preparation device for preparing the multi-layer microcapsules for dual-core temperature-sensitive inhibition of coal spontaneous combustion in Example 1 and Example 2 through this embodiment.

[0113] Please refer to Figure 5 , the preparation device of this embodiment includes a mounting bracket 6, a fluid distribution table 7, a first double-channel liquid injection tube 1, a second double-channel liquid injection tube 2, a third double-channel liquid injection tube 3, two fluid distribution arrays 8, and a cooling device 9.

[0114] Please refer to Figure 5 , in this embodiment, the fluid distribution table 7 is arranged at the upper end of the mounting bracket 6, and three mounting seats 10 are arranged on the fluid distribution table 7. Among the three mounting seats, one mounting seat 10 is arranged in the middle of the lower end of the fluid distribution table 7, and the other two mounting seats 10 are respectively located on both sides of the upper end of the fluid distribution table 7.

[0115] The first double-channel liquid injection pipe 1 and the second double-channel liquid injection pipe 2 are respectively vertically installed on the two mounting seats 10 at the upper end of the fluid distribution table 7; the third double-channel liquid injection pipe 3 is installed on the mounting seat 10 at the lower end of the fluid distribution table 7.

[0116] The cooling device 9 is arranged at the bottom of the mounting bracket 6, and the input end of the cooling device 9 is located directly below the output end of the third double-channel liquid injection pipe 3, so that the third composite phase liquid droplet balls formed by the third double-channel liquid injection pipe 3 fall into the cooling device 9 for cooling and solidification to obtain the multi-layer microcapsules.

[0117] Among them, the first double-channel liquid injection pipe 1, the second double-channel liquid injection pipe 2 and the third double-channel liquid injection pipe 3 have the same structure, and both include an inner pipe 4 and an outer pipe 5 arranged coaxially.

[0118] The inner pipe 4 has a hollow structure for transporting the inner phase components, and an outer phase component transport channel for transporting the outer phase components is formed between the outer wall of the inner pipe 4 and the outer pipe 5.

[0119] One of the fluid distribution arrays 8 is arranged between the output end of the first double-channel liquid injection pipe 1 and the input end of the inner pipe 4 of the third double-channel liquid injection pipe 3, and the other fluid distribution array 8 is arranged between the output end of the second double-channel liquid injection pipe 2 and the input end of the inner pipe 4 of the third double-channel liquid injection pipe 3.

[0120] When using the preparation device of this embodiment to prepare the multi-layer microcapsules for dual-core temperature-sensitive inhibition of coal spontaneous combustion, syringes are connected to the input ends of the inner pipe 4 and the outer phase component transport channels of the first double-channel liquid injection pipe 1 and the second double-channel liquid injection pipe 2 respectively, and corresponding inner phase components or outer phase components are filled in each syringe, so as to inject the corresponding inner phase components or outer phase components through the corresponding syringes. Among them, it should be noted that the operation of connecting syringes to inject inner phase components or outer phase components is a conventional means in the art, and those skilled in the art should know, so the present invention will not elaborate here.

[0121] In a preferred embodiment of the present invention, the cooling device 9 used is a liquid-receiving cooling tray, and deionized water is placed in the liquid-receiving cooling tray.

[0122] Comparative Example 1

[0123] This comparative example is a microcapsule with a multi-layer structure arranged concentrically proposed in the initial exploration stage of the present invention.

[0124] Please refer to Figure 1 , the microcapsule of this comparative example also has a four-layer structure, that is, this comparative example provides a concentric four-layer microcapsule.

[0125] From Figure 1 it can be seen that the outer shell B in this comparative example is formed by an oil-phase low-order temperature-sensitive wall material, and the oil-phase low-order temperature-sensitive wall material in this embodiment is formed by mixing 40# chlorinated paraffin, ammonium polyphosphate and glass fiber. The addition amount of 40# chlorinated paraffin is 7 times the mass of the glass fiber, and the addition amount of ammonium polyphosphate is 2 times the mass of the glass fiber, so that the melting point of the outer shell B in this embodiment is about 40°C.

[0126] The second layer is the liquid-phase inhibitor core material X, and the liquid-phase inhibitor core material X is an aqueous solution of tea polyphenols with a mass fraction of 70%.

[0127] The third layer is the inner shell B1 in the temperature-sensitive inhibitor pellets. The inner shell B1 is 70# chlorinated paraffin, so that the melting point of the inner shell in this comparative example is about 70°C.

[0128] The fourth layer is the liquid-phase acidic core material X1 wrapped in the inner shell B1. The liquid-phase acidic core material X1 is an aqueous solution of vitamin C with a mass fraction of 70%.

[0129] The preparation method of the microcapsule of this comparative example, and the difference between this comparative example and Example 1 is only that:

[0130] Only one double-channel liquid injection tube set above is used, and other preparation steps are the same as those in Example 1, so as to obtain the microcapsule structure as Figure 1 shown.

[0131] Based on the above, the microcapsule of this comparative example is similar to that of Example 1, and can also release materials layer by layer from the first layer to the fourth layer for preventing and controlling coal spontaneous combustion. However, when the microcapsule of this comparative example is in use, if the initial physical and chemical inhibition of the tea polyphenol solution fails over time and the coal temperature rises to 70°C, the oil-phase high-order temperature-sensitive wall material B1 of the microcapsule is heated and melted, and only a single liquid-phase acidic core material X1 can be released for a certain degree of chemical inhibition, and the inerting effect of generating CO2 gas in Example 1 of the present invention cannot be achieved, that is, the comparative example cannot achieve the "inerting-inhibiting" effect of coal spontaneous combustion of the present invention.

[0132] Obviously, the above embodiments are only a part of the embodiments of the present invention, rather than all embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the scope of protection of the present invention.

Claims

1. A multi-layer microcapsule for inhibiting coal spontaneous combustion with dual-core temperature sensitivity, characterized in that, It includes an outer shell, as well as a first temperature-sensitive inhibitor ball and a second temperature-sensitive inhibitor ball distributed inside the outer shell; The first temperature-sensitive inhibitor ball includes a first inner shell, and a liquid-phase acidic core material wrapped inside the first inner shell; The second temperature-sensitive inhibitor ball includes a second inner shell, and a liquid-phase alkaline core material wrapped inside the second inner shell; Wherein, a liquid-phase inhibitor core material is filled between the first inner shell, the second inner shell and the outer shell; The outer shell is formed by an oil-phase low-order temperature-sensitive wall material; Both the first inner shell and the second inner shell are formed by an oil-phase high-order temperature-sensitive wall material; The liquid-phase inhibitor core material is an antioxidant solution or an ionic liquid; The oil-phase low-order temperature-sensitive wall material is made of a temperature-sensitive material, a flame retardant material and a strengthening material; wherein, based on the strengthening material, the addition amount of the temperature-sensitive material is 6.5 to 7.5 times the mass of the strengthening material; the addition amount of the flame retardant material is 1.5 to 2.5 times the mass of the strengthening material; The temperature-sensitive material is one or more of chlorinated paraffin, polyethylene glycol and polyvinyl chloride; Wherein, the chlorinated paraffin is one or more of 30# chlorinated paraffin to 50# chlorinated paraffin; The flame retardant material is one or more of ammonium polyphosphate, zinc borate hydrate and aluminum hydroxide; The strengthening material is one or more of diatomite, montmorillonite, polyacrylamide and glass fiber; The oil-phase high-order temperature-sensitive wall material is one or more of 50# chlorinated paraffin to 90# chlorinated paraffin.

2. The multi-layer microcapsule for inhibiting coal spontaneous combustion with dual cores and temperature sensitivity as described in claim 1, wherein, The antioxidant solution is prepared from an antioxidant and water; The mass fraction of the antioxidant in the antioxidant solution is 40% to 70%; The antioxidant is one or more of rosmarinic acid, tea polyphenols, proanthocyanidins and vitamin C.

3. The multi-layer microcapsule for inhibiting coal spontaneous combustion with dual cores and temperature sensitivity according to claim 1, wherein, The ionic liquid is an imidazole-based ionic liquid.

4. The multi-layer microcapsule for inhibiting coal spontaneous combustion with dual cores and temperature sensitivity according to claim 1, wherein The liquid-phase acidic core material is an acidic salt aqueous solution.

5. The multi-layer microcapsule for dual-core temperature-sensitive inhibition of coal spontaneous combustion according to claim 1, wherein, The liquid-phase alkaline core material is a bicarbonate aqueous solution.

6. A method for preparing a multi-layer microcapsule for inhibiting coal spontaneous combustion with dual-core temperature sensitivity according to any one of claims 1 to 5, characterized in that, It includes the following steps: Prepare a preparation device: Prepare a cooling device and a first double-channel liquid injection tube (1), a second double-channel liquid injection tube (2) and a third double-channel liquid injection tube (3) with the same structure; The first double-channel liquid injection tube (1), the second double-channel liquid injection tube (2) and the third double-channel liquid injection tube (3) all include an inner tube (4) and an outer tube (5) arranged coaxially; The inner tube (4) serves as an inner-phase component delivery channel, and an outer-phase component delivery channel is formed between the outer wall of the inner tube (4) and the outer tube (5); The first double-channel liquid injection tube (1), the second double-channel liquid injection tube (2) and the third double-channel liquid injection tube (3) are all arranged vertically, the first double-channel liquid injection tube (1) and the second double-channel liquid injection tube (2) are at the same horizontal height, the third double-channel liquid injection tube (3) is arranged below the first double-channel liquid injection tube (1) and the second double-channel liquid injection tube (2), and the cooling device is arranged directly below the output end of the third double-channel liquid injection tube (3); The output ends of the first double-channel liquid injection tube (1) and the second double-channel liquid injection tube (2) are respectively connected to the input end of the inner-phase component delivery channel in the third double-channel liquid injection tube (3) through a fluid distribution array (8); Taking the liquid-phase acidic core material as the inner-phase component and the molten liquid of the oil-phase high-order temperature-sensitive wall material obtained by melting the oil-phase high-order temperature-sensitive wall material as the outer-phase component, respectively injecting them into the corresponding conveying channels of the first double-channel liquid injection tube (1) to form the first composite-phase droplet ball corresponding to the first temperature-sensitive inhibitor ball; Taking the liquid-phase alkaline core material as the inner-phase component and the molten liquid of the oil-phase high-order temperature-sensitive wall material obtained by melting the oil-phase high-order temperature-sensitive wall material as the outer-phase component, respectively injecting them into the corresponding conveying channels of the second double-channel liquid injection tube (2) to form the second composite-phase droplet ball corresponding to the second temperature-sensitive inhibitor ball; Taking the first composite-phase droplet ball, the second composite-phase droplet ball and the liquid-phase inhibitor core material together as the inner-phase component and the molten liquid obtained by melting the oil-phase low-order temperature-sensitive wall material as the outer-phase component, respectively injecting them into the corresponding conveying channels of the third double-channel liquid injection tube (3) to form the third composite-phase droplet ball; the formed third composite-phase droplet ball falls into the cooling device for cooling and solidification to obtain the multi-layer microcapsule.

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