Microcapsule cementing plugging material as well as preparation method and application thereof

Abstract

The invention discloses a microcapsule cementing plugging material and a preparation method and application thereof. The microcapsule cementing plugging material comprises a microcapsule wall and an expansion cementing agent, the expansion cementing agent comprises a core agent and an enhancer; the core agent is prepared from a carbon supply component, an acid supply component and a gas supply component; the reinforcing agent is prepared from sepiolite, muscovite, Al (OH) 3, nano titanium dioxide and graphene nanosheets. The preparation method comprises the following steps: dispersing an expansion cementing agent in a water phase containing polyethylene glycol to form a water-phase dispersion system, dissolving toluene diisocynate in cyclohexane to form an organic phase, dropwise adding the organic phase into the water-phase dispersion system under stirring, carrying out a polymerization reaction at an oil-water interface, forming a coating film on the surface of the expansion cementing agent by a generated polyurethane polymer, and carrying out heat treatment to obtain the polyurethane-modified expansion cementing agent. And washing to obtain the plugging material. The preparation process is simple, low in cost and safe and environment-friendly in production process; the obtained microcapsule cementation plugging material is wrapped and conveyed through liquid drops, so that expansion cementation plugging, heat insulation and cooling of an underground high-temperature fire area are realized, and oxidation and recombustion of a coal fire source are inhibited.

Description

Technical Field

[0001] The present invention relates to a fire prevention and extinguishing material and its preparation method and application, and particularly relates to a microcapsule cementing plugging material and its preparation method and application, belonging to the technical fields of coal mine flame retardancy and fire prevention and control. Background Art

[0002] With the continuous growth of the global demand for energy and mineral resources, the depth of mine exploitation is increasing day by day, and the exploitation scope is continuously expanding. Especially, the exploitation operations under complex geological conditions such as steeply inclined coal seams are becoming more and more frequent. In steeply inclined mining, the large inclined "roof fall" damage area with large height difference has serious air leakage, a large amount of residual coal distributed at high positions, a long time for withdrawing supports during end mining, serious fragmentation of top coal, good oxidation heat storage and fast spontaneous combustion, which seriously threatens the safe exploitation underground.

[0003] Traditional fire prevention materials and treatment technologies for steeply inclined coal seams underground are difficult to meet the new safety requirements. The traditional grouting materials have poor crack filling effects on damaged coal seams, and poor fluidity and permeability; the inhibitor has a short action time at high temperatures and is difficult to effectively block the interaction between oxygen and flame; the polyurethane-based flame retardant materials rapidly deteriorate in performance under long-term high temperatures. In view of this, there is an urgent need for a more advanced and comprehensive material for treating high-temperature combustion areas underground, and having certain inhibitor and anti-rekindling properties, so as to effectively control underground fire accidents, reduce carbon emissions, and ensure the safety of personnel's lives and the smooth progress of mine production. Summary of the Invention

[0004] The purpose of the present invention is to provide a microcapsule cementing plugging material and its preparation method and application. The preparation process is simple, the cost is low, and the production process is safe and environmentally friendly; the prepared microcapsule cementing plugging material can achieve expansion cementing plugging in high-temperature areas underground, insulate heat and reduce temperature, inhibit the oxidation and rekindling of coal fire sources, and expand new ideas for precise prevention and control of fire sources in high-temperature areas underground.

[0005] To achieve the above purpose, the present invention provides a microcapsule cementing plugging material, which is composed of a microcapsule wall and an expansion cementing agent wrapped inside the microcapsule wall, and the mass ratio between the expansion cementing agent and the microcapsule wall is 1:(3 - 4);

[0006] The expansion cementing agent includes the following raw materials in parts by weight: 80 - 88 parts of a core agent and 12 - 16 parts of a strengthening agent;

[0007] The core agent includes the following raw materials in parts by weight: 30 - 50 parts of a carbon-supplying component, 8 - 12 parts of an acid-supplying component, and 8 - 12 parts of a gas-supplying component; the strengthening agent is composed of the following raw materials in parts by weight: 2 - 4 parts of sepiolite, 1 - 3 parts of muscovite, 1 - 3 parts of Al(OH)3, 0.5 - 3 parts of nano-titanium dioxide, and 0.5 - 3 parts of graphene nanosheets.

[0008] Preferably, the carbon source component is one or more of glucose, sorbitol, and sucrose, the acid source component is one or more of ammonium polyphosphate and ammonium dihydrogen phosphate, and the gas source component is one or more of urea, sodium bicarbonate, and polylactic acid.

[0009] Preferably, the microcapsule wall is prepared from toluene diisocyanate and polyethylene glycol with a mass ratio of 1:(1.5 - 2.0).

[0010] To achieve the above object, the present invention also provides a preparation method of the above microcapsule cement plugging material, which includes the following steps:

[0011] S1. Grind and fully mix the carbon source component, acid source component, and gas source component according to the ratio to obtain a core agent; fully mix sepiolite, muscovite, Al(OH)3, nano-titanium dioxide, and graphene nanosheets according to the ratio to obtain a strengthening agent; fully mix the core agent and the strengthening agent according to the ratio to obtain an expanding cementing agent;

[0012] S2. Disperse the expanding cementing agent in an aqueous phase containing polyethylene glycol, and add sodium dodecyl sulfate as a dispersion stabilizer to form an aqueous phase dispersion system; the concentration of polyethylene glycol in the aqueous phase dispersion system is 15 - 25 wt%, and the concentration of sodium dodecyl sulfate in the aqueous phase dispersion system is 0.1 - 0.5 wt%;

[0013] S3. Dissolve toluene diisocyanate in cyclohexane to form an organic phase, and the concentration of toluene diisocyanate in the organic phase is 30 - 50 wt%;

[0014] S4. Under stirring, drop the organic phase prepared in step S3 into the aqueous phase dispersion system formed in step S2 at a dropping rate of 5 - 10 mL / min, the stirring speed is 1000 - 1200 r / min, the reaction temperature is controlled at 60 - 80 °C, and the reaction time is 2 - 4 h. The organic phase and the aqueous phase undergo a polymerization reaction at the oil-water interface, and the generated polyurethane polymer forms a coating film on the surface of the expanding cementing agent to obtain microcapsules encapsulating the expanding cementing agent;

[0015] S5. Wash repeatedly with a solvent prepared by mixing ethanol and cyclohexane in a volume ratio of 3:1 to obtain a microcapsule cement plugging material with a particle size range of 180 - 106 μm.

[0016] To achieve the above object, the present invention also provides an application of the above microcapsule cement plugging material in blocking the combustion and reignition of a fire area in a coal mine underground.

[0017] Further, the specific application process is as follows: The microcapsule cement plugging material is prepared into droplets, and after wrapping the microcapsule cement plugging material, it is transported to the high-temperature underground fire area. Under the action of high temperature, the atomized droplets rupture, releasing the microcapsule cement plugging material, and forming an expanded cemented dense plugging layer with heat insulation and oxygen isolation functions to block the combustion of the fire area.

[0018] Further, a conveying pipeline is used to connect the reaction kettle and the double-jet impact atomizing nozzle. The double-jet impact atomizing nozzle is internally provided with a double-liquid spray channel. The double-jet impact atomizing nozzle is combined with ultrasonic atomization to uniformly form high-specific-surface-area droplets in an atomized form by wrapping the microcapsule cement plugging material with droplets, achieving precise and comprehensive coverage of the high-temperature underground fire area.

[0019] Further, the preparation process of the droplets wrapping the microcapsule cement plugging material is as follows:

[0020] a. Prepare the emulsifying component; the emulsifying component consists of a continuous phase, a dispersed phase, and an emulsifier, and their mass ratio is 1:0.7 - 0.75:0.05 - 0.08.

[0021] The continuous phase is compounded from 50 - 60 wt% of n-decane, 30 - 40 wt% of polyethylene glycol solution, and 10 - 15 wt% of silicone oil;

[0022] The dispersed phase is an aqueous solution containing 25 wt% of the microcapsule expansion cement binder plugging material described in claim 1;

[0023] The emulsifier adopts a compound emulsifier system of Span80 and Tween80 with a mass ratio of 3:1, and rhamnolipid accounting for 1 wt% of the total amount of this compound emulsifier is added to form a ternary compound emulsifier.

[0024] b. Emulsification treatment: In the reaction kettle, emulsification is carried out by using a stirring device and an ultrasonic assistance device; first, the dispersed phase and the emulsifier are added to the reaction kettle, the stirring is started to make them preliminarily mixed evenly, and then the continuous phase is slowly added, and stirring is carried out to obtain the droplets wrapping the microcapsule cement plugging material.

[0025] Further, the specific application process is as follows: The microcapsule cement plugging material is transported through droplets to the area of secondary oxidized coal in the oxidation zone of the goaf, or to the abnormal area after laying the net and covering the skin between the supports in the goaf during the final mining stage of the underground to effectively block coal spontaneous combustion or re-ignition.

[0026] Compared with the prior art, the present invention has the following advantages:

[0027] 1. High-efficiency plugging and inhibition: Under high-temperature action, the microcapsule cement plugging material of the present invention can rapidly release the expansion cementing agent and form a dense plugging layer of expanded cementing at high temperature, which has good heat insulation and oxygen isolation effects, effectively blocks the combustion in the fire area, and has a certain inhibition effect. Compared with traditional grouting materials, it has better fire extinguishing, cooling and barrier effects, and can significantly improve the underground fire prevention performance.

[0028] 2. Stable transportation and atomization: Adopting a unique droplet wrapping method for transportation, the microcapsule cement plugging material maintains good stability and fluidity during transportation, and can save a large amount of water resources at the same time; relying on double-jet impinging atomization and ultrasonic atomization, tiny droplets are formed with good dispersibility in the air, which can quickly diffuse and evenly distribute in the fire area space, solving the problems of simple transportation methods of traditional fire prevention materials, easy occurrence of fire prevention loopholes or waste.

[0029] 3. Full-scenario fire prevention application: It is not only applicable to the prevention and control of coal combustion in large dip angle high-position void areas, but also can be transported to the area of secondary oxidized coal in the oxidation zone of the goaf to inhibit the secondary oxidation and spontaneous combustion of coal; at the same time, it meets the use in abnormal areas after laying mesh skins between supports during the final mining stage underground, and can effectively block the spontaneous combustion or reignition of coal, comprehensively covering all key fire prevention scenarios in coal mine mining. Brief Description of the Drawings

[0030] Figure 1 It is a schematic diagram of the preparation process of the present invention;

[0031] Figure 2 It is a schematic diagram of the fire prevention and extinguishing test system for inclined coal seams;

[0032] Figure 3 It is a schematic diagram of the inhibition performance of the microcapsule cement plugging material prepared in Example 2;

[0033] Figure 2 In the figure: 1. Temperature inspection instrument, 2. Thermal radiation sensor, 3. Water storage bottle, 4. Angle adjustment mechanism, 5. Air generator, 6. Temperature controller, 7. Heating plate, 8. Coal body, 9. Environment analyzer, 10. Thermal imager, 11. Storage tank, 12. Thermocouple, 13. Heating wire, 14. Waste liquid treatment pool, 15. Chromatograph, 16. Cleaning filter, 17. Computer. Detailed Embodiments

[0034] The present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0035] Example 1

[0036] A microcapsule cement plugging material is composed of a microcapsule wall and an expansion cementing agent wrapped inside, and the mass ratio between the expansion cementing agent and the microcapsule wall is 1:3.

[0037] The expansion binder comprises the following raw materials in parts by weight: 80 parts of a core agent and 12 parts of a strengthening agent;

[0038] The core agent comprises the following raw materials in parts by weight: 30 parts of glucose, 8 parts of ammonium polyphosphate, and 8 parts of urea; the strengthener comprises the following raw materials in parts by weight: 2 parts of sepiolite, 1 part of muscovite, 1 part of Al(OH)3, 0.5 parts of nano titanium dioxide, and 0.5 parts of graphene nanosheets.

[0039] The microcapsule wall is prepared from toluene diisocyanate and polyethylene glycol in a mass ratio of 1:1.5.

[0040] like Figure 1 As shown, the preparation method of the above-mentioned microcapsule cementing plugging material comprises the following steps:

[0041] S1. Grind glucose, ammonium polyphosphate and urea according to a ratio and mix them thoroughly to obtain a core agent; mix sepiolite, muscovite, Al(OH)3, nano-titanium dioxide and graphene nanosheets according to a ratio to obtain a reinforcing agent; and mix the core agent and the reinforcing agent according to a ratio to obtain an expansion adhesive;

[0042] S2, dispersing 30g of the swelling binder in an aqueous phase containing 54g of polyethylene glycol, and adding sodium lauryl sulfate as a dispersion stabilizer to form an aqueous phase dispersion system, wherein the concentration of the polyethylene glycol in the aqueous phase dispersion system is 15wt%, and the concentration of the sodium lauryl sulfate in the aqueous phase dispersion system is 0.1wt%;

[0043] S3, dissolving 36 g of toluene diisocyanate in cyclohexane to form an organic phase, wherein the concentration of toluene diisocyanate in the organic phase is 30 wt %;

[0044] S4, under stirring, the organic phase prepared in step S3 is added dropwise to the aqueous phase dispersion system formed in step S2 at a dropping speed of 5 mL / min, the stirring speed is 1000 r / min, the reaction temperature is controlled at 60° C., the reaction time is 2 h, the organic phase and the aqueous phase undergo polymerization reaction at the oil-water interface, and the generated polyurethane polymer forms a coating film on the surface of the swelling binder to obtain microcapsules that wrap the swelling binder;

[0045] S5. Use a solvent mixed with ethanol and cyclohexane in a volume ratio of 3:1 to perform multiple washings to remove unreacted monomers and impurities, improve the purity of the microcapsules to adapt to subsequent processes, and obtain a microcapsule cementing and plugging material with a particle size range of 180-106 μm.

[0046] The microcapsule cement plugging material prepared in this embodiment is applied to block the combustion and re-ignition of the fire area in the coal mine. The specific application process is as follows: The microcapsule cement plugging material is prepared into droplets to wrap the microcapsule cement plugging material and then transported to the high-temperature fire area underground. Under the influence of temperature, the atomized droplets break, causing the microcapsule cement plugging material to be exposed to the high-temperature environment. The heat-receiving microcapsules release the cement plugging material, and then an expanded cement plugging layer with heat insulation and oxygen isolation effects is formed to block the combustion of the fire area.

[0047] A conveying pipeline is used to connect the reaction kettle and the double-jet counter-flow atomizing nozzle. In the conveying pipeline, the droplet wrapping effect enables the microcapsule cement plugging material to maintain good stability and fluidity, and at the same time can save a large amount of water resources. The double-jet counter-flow atomizing nozzle is internally provided with a double-spray liquid flow channel. The double-jet counter-flow atomizing nozzle is combined with ultrasonic atomization to uniformly form high-specific-surface-area droplets by atomizing the droplet-wrapped microcapsule cement plugging material, and then transport them to the high-temperature fire area underground. For example, it is transported to the large-inclination high-position cavity area, the secondary oxidation coal area in the oxidation zone of the goaf, or the abnormal area after laying a net and covering the skin between the supports in the goaf during the final mining stage of the underground to block coal spontaneous combustion or re-ignition.

[0048] The preparation process of the droplet-wrapped microcapsule cement plugging material is as follows:

[0049] a. Prepare the emulsifying components; the emulsifying components are composed of a continuous phase, a dispersed phase, and an emulsifier, and their mass ratio is 1:0.7:0.05.

[0050] The continuous phase is compounded from 50 wt% of n-decane, 30 wt% of polyethylene glycol solution, and 10 wt% of silicone oil;

[0051] The dispersed phase contains an aqueous solution of 25 wt% of the microcapsule expansion cementing agent plugging material;

[0052] The emulsifier uses a composite emulsifier system of Span80 and Tween80 with a mass ratio of 3:1, and 1 wt% of rhamnolipid is added to the total amount of the composite emulsifier to form a ternary composite emulsifier;

[0053] b. Emulsification treatment: In the reaction kettle, use a stirring device and an ultrasonic auxiliary device for emulsification; first add the dispersed phase and the emulsifier to the reaction kettle, start stirring to make them preliminarily mixed evenly, and then slowly add the continuous phase and stir to obtain the droplet-wrapped microcapsule cement plugging material.

[0054] Example 2

[0055] A microcapsule cement plugging material is composed of a microcapsule wall and an encapsulated expansion cementing agent. The mass ratio between the expansion cementing agent and the microcapsule wall is 1:3.5.

[0056] The swelling cementing agent comprises the following raw materials in parts by weight: 84 parts of a core agent and 16 parts of a strengthening agent;

[0057] The core agent comprises the following raw materials in parts by weight: 40 parts of glucose, 10 parts of ammonium polyphosphate, and 10 parts of urea; the strengthening agent is composed of the following raw materials in parts by weight: 3 parts of sepiolite, 2 parts of muscovite, 2 parts of Al(OH)3, 1.5 parts of nano-titanium dioxide, and 1.5 parts of graphene nanosheets.

[0058] The microcapsule wall is prepared from toluene diisocyanate and polyethylene glycol in a mass ratio of 1:1.8.

[0059] As Figure 1 shown, the preparation method of the above microcapsule cementing plugging material comprises the following steps:

[0060] S1. The same as in Example 1;

[0061] S2. Disperse 30 g of the swelling cementing agent in an aqueous phase containing 63 g of polyethylene glycol, and add sodium dodecyl sulfate as a dispersion stabilizer to form an aqueous phase dispersion system. The concentration of polyethylene glycol in the aqueous phase dispersion system is 20 wt%, and the concentration of sodium dodecyl sulfate in the aqueous phase dispersion system is 0.3 wt%;

[0062] S3. Dissolve 42 g of toluene diisocyanate in cyclohexane to form an organic phase. The concentration of toluene diisocyanate in the organic phase is 40 wt%;

[0063] S4. Under stirring, add the organic phase prepared in step S3 dropwise to the aqueous phase dispersion system formed in step S2 at a dropping rate of 7 mL / min. The stirring speed is 1100 r / min, the reaction temperature is controlled at 70 °C, and the reaction time is 3 h. The organic phase and the aqueous phase undergo a polymerization reaction at the oil-water interface, and the generated polyurethane polymer forms a coating film on the surface of the swelling cementing agent to obtain microcapsules encapsulating the swelling cementing agent;

[0064] S5. The same as in Example 1.

[0065] Apply the microcapsule cementing plugging material prepared in this example to the prevention of fire area combustion and re-ignition in coal mines. The specific application process is the same as in Example 1.

[0066] The preparation process of the droplet-encapsulated microcapsule cementing plugging material is as follows:

[0067] a. Prepare an emulsifying component; the emulsifying component consists of a continuous phase, a dispersed phase, and an emulsifier, and their mass ratio is 1:0.72:0.06.

[0068] The continuous phase is prepared by compounding 55 wt% of n-decane, 35 wt% of polyethylene glycol solution, and 12 wt% of silicone oil;

[0069] The dispersed phase is the same as that in Example 1;

[0070] The emulsifier is the same as that in Example 1;

[0071] b. The emulsification treatment is the same as that in Example 1.

[0072] Example 3

[0073] A microcapsule cementing plugging material is composed of a microcapsule wall and an encapsulated expanding cementing agent, and the mass ratio between the expanding cementing agent and the microcapsule wall is 1:4.

[0074] The expanding cementing agent includes the following raw materials in parts by weight: 88 parts of a core agent and 14 parts of a strengthening agent;

[0075] The core agent includes the following raw materials in parts by weight: 50 parts of glucose, 12 parts of ammonium polyphosphate, and 12 parts of urea; the strengthening agent is composed of the following raw materials in parts by weight: 4 parts of sepiolite, 3 parts of muscovite, 3 parts of Al(OH)3, 3 parts of nano-titanium dioxide, and 3 parts of graphene nanosheets.

[0076] The microcapsule wall is prepared from toluene diisocyanate and polyethylene glycol in a mass ratio of 1:2.

[0077] As Figure 1 shown, the preparation method of the above microcapsule cementing plugging material includes the following steps:

[0078] S1. The same as that in Example 1;

[0079] S2. Disperse 30 g of the expanding cementing agent in an aqueous phase containing 72 g of polyethylene glycol, and add sodium dodecyl sulfate as a dispersion stabilizer to form an aqueous phase dispersion system. The concentration of polyethylene glycol in the aqueous phase dispersion system is 25 wt%, and the concentration of sodium dodecyl sulfate in the aqueous phase dispersion system is 0.5 wt%;

[0080] S3. Dissolve 48 g of toluene diisocyanate in cyclohexane to form an organic phase, and the concentration of toluene diisocyanate in the organic phase is 50 wt%;

[0081] S4. Under stirring, drop the organic phase prepared in step S3 into the aqueous phase dispersion system formed in step S2 at a dropping rate of 10 mL / min. The stirring speed is 1200 r / min, the reaction temperature is controlled at 80 °C, and the reaction time is 4 h. A polymerization reaction occurs at the oil-water interface between the organic phase and the aqueous phase, and the generated polyurethane polymer forms a coating film on the surface of the expanding cementing agent to obtain microcapsules encapsulating the expanding cementing agent;

[0082] S5. The same as that in Example 1.

[0083] The microcapsule cement plugging material prepared in this embodiment is applied to block the combustion and reignition of the fire area in the coal mine underground, and the specific application process is the same as that in Embodiment 1.

[0084] The preparation process of the droplet-wrapped microcapsule cement plugging material is as follows:

[0085] a. Prepare the emulsifying components; the emulsifying components are composed of a continuous phase, a dispersed phase and an emulsifier, and their mass ratio is 1:0.75:0.08.

[0086] The continuous phase is compounded from 60 wt% of n-decane, 40 wt% of polyethylene glycol solution and 15 wt% of silicone oil;

[0087] The dispersed phase is the same as that in Embodiment 1;

[0088] The emulsifier is the same as that in Embodiment 1;

[0089] b. The emulsification treatment is the same as that in Embodiment 1.

[0090] Next, the application performance of the microcapsule cement plugging materials prepared in Examples 1-3 was studied, and the specific research methods and results are as follows:

[0091] Application Example 1, test the expansion ratio

[0092] The determination of the expansion ratio (η) is achieved by the sand replacement method, which is defined as the ratio of the volume after the material expands to the initial volume, that is, the expansion ratio calculation formula is where V0 is the volume of the container, m initial sand and m expanded sand are the replacement masses of the sand before and after expansion respectively. The results are shown in Table 1 below. It can be seen that the traditional fire extinguishing method in the comparative example does not have the expansion performance and has poor heat insulation and oxygen isolation performance, while the microcapsule cement plugging materials prepared in the examples all have the expansion performance. Among them, the microcapsule cement plugging material prepared in Example 2 reached an expansion ratio of 24 during the application process, and the effect was remarkable.

[0093] Application Example 2, test the fire extinguishing effect at 1500S

[0094] To further test the fire extinguishing and cooling performance of the prepared microcapsule cement plugging material, through such as Figure 2The self-made inclined coal seam fire prevention and extinguishing test system shown in the figure is tested. The test system can simulate different real environments underground with different inclination degrees, and has the functions of testing the spontaneous combustion characteristics of coal seams and the fire extinguishing effect. The temperature patrol meter 1 and the thermal radiation meter sensor 2 are used to measure the temperature and thermal radiation respectively, the thermocouple 12 transmits signals to the temperature patrol meter 1, and other structures assist the complete operation of the system. First, the ambient humidity is adjusted by atomizing the pure water stored in the water storage bottle 3, the coal seam inclination is adjusted by the angle adjustment mechanism 4, and the air generator 5 is turned on to supply oxygen and the heating wire 13; then, the temperature controller 6 controls the heating plate 7 to heat to a certain temperature to ignite the coal body 8, and after the environmental analyzer 9 and the thermal imager 10 detect that the coal has burned to a certain extent, the microcapsule expansion binder in the storage tank 11 is transported to the combustion area in the box through droplets, and then the thermal radiation meter sensor 2 acquisition system and the temperature patrol meter 1 are immediately turned on to monitor the central temperature and thermal radiation of the coal body when the fire is extinguished for 1500S, and the obtained data are recorded and analyzed by the computer 17. The results are shown in Table 1. It can be seen that the temperature of the coal sample in Example 2 has dropped to 50°C, which is lower than the critical temperature of coal (70°C), and the effect is ideal.

[0095] Table 1 Performance test results of comparative examples and embodiments

[0096]

[0097] As shown in Table 1, by comparing Examples 1-3, it can be seen that the plugging material prepared in Example 2 performs best in terms of expansion and bonding ratio and fire extinguishing and cooling effect, which indicates that the microcapsule expanded and bonded carbon material at this ratio has better performance in underground fire prevention applications. Of course, in actual applications, the appropriate ratio of materials can be selected according to specific needs and cost considerations.

[0098] Application example 3, testing the resistance performance

[0099] In order to further test the anti-reignition ability of the microcapsule cementing plugging material prepared in Example 2, Figure 2 The chromatogram 15 in the inclined coal seam fire prevention and extinguishing test system shown in the figure is tested. During the test, the cleaning filter 16 needs to be opened. After the test, the system is cleaned and discharged into the waste liquid treatment pool 14. First, the resistant coal sample is prepared, including adding pure water to resist and adding microcapsule cementing plugging material to resist the sample. Then, the resistant coal sample and the original coal sample are subjected to a standard programmed temperature resistance experiment to obtain the CO generation concentration of the original coal and each resistant coal sample. The specific data is shown in Figure 3(In the figure, the raw coal represents the untreated Nalinhe coal). It can be seen that the CO generation concentration of the raw coal is 30960 ppm at 210 °C. The CO generation concentration of the coal sample treated with pure water is 25370 ppm at 210 °C, which is 18.1% lower than that of the raw coal. The CO generation concentration of the coal sample treated with the microcapsule cementitious plugging material is 11010 ppm at 210 °C, which is 64.4% lower than that of the raw coal. The above results show that the microcapsule cementitious plugging material prepared in Example 2 has a better inhibition effect.

Claims

1. A microcapsule cementing plugging material, characterized in that, It is composed of a microcapsule wall and an expanding cementing agent encapsulated by the microcapsule wall, and the mass ratio between the expanding cementing agent and the microcapsule wall is 1:(3 - 4); The expanding cementing agent includes the following raw materials in parts by weight: 80 - 88 parts of a core agent and 12 - 16 parts of a strengthening agent; The core agent includes the following raw materials in parts by weight: 30 - 50 parts of a carbon - supplying component, 8 - 12 parts of an acid - supplying component, and 8 - 12 parts of a gas - supplying component; The strengthening agent is composed of the following raw materials in parts by weight: 2 - 4 parts of sepiolite, 1 - 3 parts of muscovite, 1 - 3 parts of Al(OH)3, 0.5 - 3 parts of nano - titanium dioxide, and 0.5 - 3 parts of graphene nanosheets.

2. The microcapsule cementing plugging material according to claim 1, wherein The carbon - supplying component is one or more of glucose, sorbitol, and sucrose, the acid - supplying component is one or more of ammonium polyphosphate and ammonium dihydrogen phosphate, and the gas - supplying component is one or more of urea, sodium bicarbonate, and polylactic acid.

3. The microcapsule cementing plugging material according to claim 1, characterized in that The microcapsule wall is prepared from toluene diisocyanate and polyethylene glycol with a mass ratio of 1:(1.5 - 2.0).

4. A preparation method of the microcapsule cementing plugging material according to any one of claims 1-3, characterized in that, It includes the following steps: S1. Grind and fully mix the carbon - supplying component, acid - supplying component, and gas - supplying component according to the ratio to obtain the core agent; fully mix sepiolite, muscovite, Al(OH)3, nano - titanium dioxide, and graphene nanosheets according to the ratio to obtain the strengthening agent; fully mix the core agent and the strengthening agent according to the ratio to obtain the expanding cementing agent; S2. Disperse the expanding cementing agent in an aqueous phase containing polyethylene glycol, and add sodium dodecyl sulfate as a dispersion stabilizer to form an aqueous - phase dispersion system; The concentration of polyethylene glycol in the aqueous - phase dispersion system is 15 - 25wt%, and the concentration of sodium dodecyl sulfate in the aqueous - phase dispersion system is 0.1 - 0.5wt%; S3. Dissolve toluene diisocyanate in cyclohexane to form an organic phase, and the concentration of toluene diisocyanate in the organic phase is 30 - 50wt%; S4. Under stirring, drop the organic phase prepared in step S3 into the aqueous - phase dispersion system formed in step S2 at a dropping rate of 5 - 10 mL / min, with a stirring speed of 1000 - 1200 r / min, control the reaction temperature at 60 - 80°C, and the reaction time is 2 - 4 h. The organic phase and the aqueous phase undergo a polymerization reaction at the oil - water interface, and the generated polyurethane polymer forms a coating film on the surface of the expanding cementing agent to obtain microcapsules encapsulating the expanding cementing agent; S5. Wash multiple times with a solvent prepared by mixing ethanol and cyclohexane in a volume ratio of 3:1 to obtain a microcapsule cementing plugging material with a particle size range of 180 - 106 μm.

5. The application of a microcapsule cementing plugging material according to any one of claims 1 - 3 in blocking the combustion and re - combustion of a fire area in a coal mine.

6. The application according to claim 5, wherein The specific application process is as follows: Prepare the microcapsule cementing plugging material into droplet - wrapped microcapsule cementing plugging material and transport it to the high - temperature fire area underground. Under the action of high temperature, the atomized droplets break, releasing the microcapsule cementing plugging material, and forming an expanding cementing dense plugging layer with heat - insulating and oxygen - isolating effects to block the combustion of the fire area.

7. The application according to claim 6, wherein A conveying pipeline is used to connect a reaction kettle and a double-jet impinging atomizing nozzle. The double-jet impinging atomizing nozzle is internally provided with a double-liquid spraying flow channel. The double-jet impinging atomizing nozzle is combined with ultrasonic atomization to wrap the microcapsule cement plugging material with droplets and uniformly form high-specific-surface-area droplets in an atomized form, achieving precise and comprehensive coverage of the underground high-temperature fire area.

8. The application according to claim 6, wherein The preparation process of the droplet-wrapped microcapsule cement plugging material is as follows: a. Prepare an emulsifying component; the emulsifying component consists of a continuous phase, a dispersed phase, and an emulsifier, and their mass ratio is 1:(0.7 - 0.75):(0.05 - 0.08); The continuous phase is compounded from 50 - 60 wt% of n-decane, 30 - 40 wt% of polyethylene glycol solution, and 10 - 15 wt% of silicone oil; The dispersed phase is an aqueous solution containing 25 wt% of the microcapsule cement plugging material described in claim 1; The emulsifier adopts a composite emulsifier system of Span80 and Tween80 with a mass ratio of 3:1, and rhamnolipid accounting for 1 wt% of the total amount of the composite emulsifier is added to form a ternary composite emulsifier; b. Emulsification treatment: In the reaction kettle, emulsification is carried out by using a stirring device and an ultrasonic auxiliary device; first, the dispersed phase and the emulsifier are added to the reaction kettle, the stirring is started to make them preliminarily mixed evenly, and then the continuous phase is slowly added, and stirring is carried out to obtain the droplet-wrapped microcapsule cement plugging material.

9. The application according to claim 5, characterized in that, The specific application process is as follows: The microcapsule cement plugging material is transported to the area of secondary oxidized coal in the oxidation zone of the goaf through droplets, or transported to the abnormal area after the mesh laying and skin covering between the supports in the goaf during the final mining stage of the underground to effectively block the spontaneous combustion or reignition of coal.

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