A method for mine carbon dioxide adsorption storage and fire retardation

Abstract

This invention discloses a method for carbon dioxide adsorption, sequestration, and flame retardancy in mines, comprising the following steps: preparing a carbon dioxide adsorption coating ZIF-8 derived porous carbon dispersion; preparing a carbon sequestration and flame retardant material: mixing a prepared mineralized bacterial solution and a saturated CaCl2 solution / saturated calcium acetate solution to obtain the carbon sequestration and flame retardant material; uniformly coating the carbon dioxide adsorption coating ZIF-8 derived porous carbon dispersion onto the surface of a coal sample in a carbon dioxide accumulation area of ​​the mine, allowing it to stand for a period of time, and after the treated coal sample has fully adsorbed carbon dioxide from the underground environment, then spraying the carbon sequestration and flame retardant material onto the surface of the coal sample to generate a calcium carbonate precipitate layer, thereby achieving carbon dioxide adsorption and sequestration and pore sealing in the goaf. This invention can achieve stable carbon sequestration and sequestration of carbon dioxide in the goaf of mines, while effectively suppressing spontaneous combustion of coal underground, fundamentally reducing underground CO2 emissions.

Description

Technical Field

[0001] This invention relates to the fields of underground carbon fixation, flame retardancy, and carbon dioxide adsorption and storage technology, and particularly to a method for carbon dioxide adsorption and storage and flame retardancy in mines, which has important applications in mine gas adsorption, spontaneous combustion suppression, safety protection, and greenhouse gas control. Background Technology

[0002] CO2 adsorption and storage (CCS) technology has attracted much attention in industries, energy, and mining, as it is an effective means of reducing greenhouse gas emissions into the atmosphere.

[0003] Currently, the main methods for carbon dioxide capture include chemical absorption, physical adsorption, membrane separation, and cryogenic distillation. However, these methods suffer from poor stability and desorption during transportation in the complex and enclosed environment of mines, resulting in poor storage performance and low capture efficiency.

[0004] Therefore, how to achieve stable carbon sequestration underground while reducing carbon dioxide emissions caused by coal spontaneous combustion, fundamentally reducing underground CO2 emissions while controlling greenhouse gases, and improving the safety of the underground working environment has important environmental and economic benefits, and is also a key issue that the coal industry urgently needs to solve. Summary of the Invention

[0005] The purpose of this invention is to provide a method for adsorption, sequestration, and flame retardancy of carbon dioxide in mines. This method can achieve stable carbon fixation and sequestration of carbon dioxide in the goaf of mines, while effectively suppressing spontaneous combustion of coal underground, thereby fundamentally reducing underground CO2 emissions.

[0006] To achieve the above objectives, the present invention provides a method for adsorption, storage, and flame retardancy of carbon dioxide in mines, comprising the following steps:

[0007] S1. Preparation of ZIF-8 carbon dioxide adsorption coating-derived porous carbon dispersion;

[0008] S2. Preparation of sealed carbon-fixing flame retardant material: The prepared mineralized bacterial solution and saturated CaCl2 solution / saturated calcium acetate solution are mixed to obtain sealed carbon-fixing flame retardant material;

[0009] S3. The carbon dioxide adsorption coating ZIF-8 derived porous carbon dispersion prepared in step S1 is uniformly coated on the surface of the coal sample in the carbon dioxide accumulation area of ​​the mine. After standing for a period of time, the treated coal sample fully adsorbs carbon dioxide in the underground environment. Then, the carbon sequestration and flame retardant material prepared in step S2 is sprayed on the surface of the coal sample to generate a calcium carbonate precipitate layer, thereby realizing carbon dioxide adsorption and sequestration and pore sealing of the goaf.

[0010] Furthermore, the specific process of step S1 is as follows:

[0011] S1-1. Prepare 2-methylimidazole solution and zinc nitrate solution separately, mix them in equal volumes and stir until clear, let stand and filter to obtain white precipitate; then wash the white precipitate with alcohol and dry to obtain ZIF-8 powder.

[0012] S1-2. ZIF-8 powder was carbonized under N2 atmosphere, and then repeatedly washed with dilute hydrochloric acid and deionized water and dried to obtain ZIF-8 derived porous carbon.

[0013] S1-3. Mix ZIF-8 derived porous carbon, activated carbon, and polyvinylidene fluoride, add N,N-dimethylacetamide, and stir to mix evenly to obtain a black slurry, which is the ZIF-8 derived porous carbon dispersion for carbon dioxide adsorption coating.

[0014] Preferably, in step S1-1, the concentration of the 2-methylimidazole solution is 0.8 mol / L and the concentration of the zinc nitrate solution is 0.15 mol / L; in steps 1-3, the mass ratio of ZIF-8 derived porous carbon, activated carbon, and polyvinylidene fluoride is 9:1:1.

[0015] Further, in step S2, the preparation process of the mineralized bacterial solution is as follows: beef extract and peptone are mixed in a sterilized container filled with distilled water, stirred until completely dissolved, and allowed to stand at room temperature to obtain the basic culture medium; after adjusting the pH of the basic culture medium to 6.5-8.5, urea solution is added to the culture medium to make the urea concentration reach 25g / L; after the culture medium is sterilized at high temperature in an autoclave, it is inoculated with Bacillus pasteurellii; the inoculated culture medium is placed in a constant temperature shaker and cultured at 25℃ and 180r / min for 36-60h to obtain the mineralized bacterial solution.

[0016] Preferably, in step S2, the mineralized bacterial solution is mixed with saturated CaCl2 solution / saturated calcium acetate solution at a volume ratio of 1:1 to obtain the sealed carbon-fixing flame retardant material.

[0017] Compared with the prior art, the present invention has the following advantages:

[0018] (1) In this invention, the carbon dioxide adsorption coating forms an adsorption coating on the surface of the target area. The coating can efficiently capture free carbon dioxide in the environment in a short time, maximize the amount of carbon dioxide adsorbed, and has the ability to efficiently adsorb carbon dioxide in the mine environment. The sealing material can not only seal the adsorbed carbon dioxide, but also physically reinforce and flame retard the goaf. In addition, the sealing material uses biological materials, which are green and environmentally friendly. While sealing carbon dioxide, it avoids the secondary pollution that traditional chemical materials may cause to the environment.

[0019] In summary, this invention introduces MOF-derived materials into the mining environment to achieve carbon sequestration through their efficient adsorption capacity. Specifically, by utilizing the excellent CO2 adsorption performance of ZIF-8-derived porous carbon materials, carbon dioxide in the mine can be effectively captured, reducing greenhouse gas emissions. This invention also combines the carbon sequestration function of ZIF-8-derived porous carbon with the flame-retardant and oxygen-barrier functions of MICP technology, spraying and sealing carbon-sequestration and flame-retardant materials to generate a calcium carbonate precipitate layer. This not only achieves stable carbon sequestration and storage of carbon dioxide but also inhibits spontaneous combustion of coal underground, solving the dual needs of carbon dioxide capture and coal spontaneous combustion prevention in mines, thereby improving mine safety and environmental benefits. Attached Figure Description

[0020] Figure 1 These are schematic diagrams illustrating the CO2 adsorption and desorption processes in various embodiments and comparative examples of the present invention;

[0021] Figure 2 This is a statistical chart of the average aperture of various embodiments and comparative examples of the present invention;

[0022] Figure 3 This is a schematic diagram of the oxidation process in Embodiment 1, Comparative Example 1, and Comparative Example 2 of the present invention. Detailed Implementation

[0023] The present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0024] Example 1

[0025] A method for adsorption, sequestration, and flame retardancy of carbon dioxide in mines includes the following steps:

[0026] S1. Preparation of ZIF-8 carbon dioxide adsorption coating-derived porous carbon dispersion;

[0027] S1-1. In a 1L beaker, mix 400mL of 0.8mol / L 2-methylimidazole solution with 400mL of 0.15mol / L zinc nitrate solution and stir continuously until the solution is clear and transparent. Then, let the mixture stand for 12 hours until the white precipitate has completely crystallized, and then perform a vacuum filtration operation. Wash the collected white precipitate with alcohol to remove impurities, and then dry it in an oven to obtain ZIF-8 powder.

[0028] S1-2. ZIF-8 powder was placed under a nitrogen atmosphere and carbonized at a high temperature of 600℃ for 4 hours. After carbonization, the product was repeatedly washed with dilute hydrochloric acid (pH<3) to remove residual impurities. Finally, the washed product was dried again to obtain ZIF-8 derived porous carbon.

[0029] S1-3. Mix the ZIF-8 derived porous carbon, activated carbon and polyvinylidene fluoride obtained in step S1-2 at a mass ratio of 9:1:1, add 5 mL of N,N-dimethylacetamide, stir and mix evenly to obtain a black slurry, which is the carbon dioxide adsorption coating ZIF-8 derived porous carbon dispersion.

[0030] S2. Preparation of sealed carbon-fixed flame retardant material: The prepared mineralized bacterial solution and saturated CaCl2 solution are mixed to obtain sealed carbon-fixed flame retardant material;

[0031] The preparation process of the mineralized bacterial solution is as follows: 3g of beef extract and 5g of peptone are added to 1000mL of distilled water and stirred until completely dissolved to obtain the basic culture medium; the pH of the culture medium is adjusted to 7.5 using NaOH solution; then urea solution is added to the culture medium to make the urea concentration reach 25g / L; after high-temperature sterilization in an autoclave, the culture medium is inoculated with Bacillus pasteurellii; the inoculated culture medium is placed in a constant temperature shaker and cultured for 48 hours at 25℃ and 180r / min to obtain the mineralized bacterial solution.

[0032] The preparation process of saturated CaCl2 solution is as follows: dissolve calcium chloride in distilled water until saturation is achieved, thus obtaining a saturated CaCl2 solution;

[0033] S3. The carbon dioxide adsorption coating ZIF-8 derived porous carbon dispersion prepared in step S1 is uniformly coated on the surface of the coal sample in the carbon dioxide accumulation area of ​​the mine. After standing for 2 hours, the coal sample fully adsorbs carbon dioxide in the underground environment. Then, the carbon sequestration and flame retardant material prepared in step S2 is sprayed on the surface of the coal sample to generate a calcium carbonate precipitate layer, thereby realizing carbon dioxide adsorption and sequestration and pore sealing of the goaf.

[0034] In use, the adsorbent material is precisely and evenly sprayed onto the carbon dioxide accumulation area in the mine and left to stand for at least 2 hours to ensure sufficient adsorption of CO2 from the environment. The carbon-fixing flame retardant material is then sprayed onto the area where CO2 has been adsorbed. Upon contact with the coal, the carbon-fixing flame retardant material further generates a dense calcium carbonate layer, filling the pores of the coal and preventing the diffusion of oxygen and CO2. Simultaneously, it converts some of the adsorbed CO2 into stable carbonates, preventing desorption. Experiments have proven that the carbon-fixing flame retardant material used in this invention can inhibit coal oxidation reactions and reduce the risk of spontaneous combustion.

[0035] Performance testing process:

[0036] 1. Adsorption and carbon fixation effect test:

[0037] The gas supply system was activated, and carbon dioxide was introduced into a sealed simulated tunnel. 5000g of lump coal (3-5cm in diameter) was deposited in the tunnel. After the CO2 concentration in the tunnel stabilized (fluctuation ≤5%), the control valve of the first storage tank was activated, and adsorbent material was evenly sprayed onto the tunnel surface (coverage ≥95%). The tunnel was left to stand for 2 hours, during which the CO2 concentration was recorded every half hour. After 2 hours, when the carbon dioxide concentration was monitored to have decreased and stabilized, the sealed carbon-fixing and flame-retardant material was simultaneously sprayed onto the tunnel surface. This was then left to stand for 2 hours to allow the material to fully react. Next, a gas chromatography instrument was connected, and argon gas was introduced to purge the treated area after the adsorbent material was sprayed, the untreated area, and the area with only the adsorbent material sprayed but not yet carbon-fixed. The gas concentration changes were then analyzed.

[0038] 2. Pore characteristics test (77K nitrogen adsorption-desorption experiment): Take 10g of 40-mesh coal powder, treat it with carbon dioxide adsorption coating and seal carbon solidification flame retardant material respectively, and put it into a 77K low temperature nitrogen adsorption-desorption experimental device to carry out adsorption-desorption experiment and analyze the porosity.

[0039] 3. Flame retardant performance test (oxidation process experiment): The prepared sample is placed in a programmed temperature riser and the temperature is raised to 200 degrees Celsius under the condition of 20% oxygen concentration. Thermogravimetric curves are obtained using thermocouples and thermobalances. The oxygen consumption rate and oxygen concentration change curves of the sample with temperature are calculated.

[0040] Example 2

[0041] A method for adsorption, sequestration, and flame retardancy of carbon dioxide in mines includes the following steps:

[0042] Steps S1 and S3 are the same as in Example 1, except for step S2;

[0043] S2. Preparation of sealed carbon-fixing flame retardant material: The prepared mineralized bacterial solution and saturated calcium acetate solution are mixed to obtain sealed carbon-fixing flame retardant material;

[0044] The pH value was adjusted to 6.5 during the preparation of the mineralized bacterial solution, and the other processes were the same as in Example 1;

[0045] The preparation process of saturated calcium acetate solution is as follows: dissolve calcium acetate in distilled water until saturation is achieved, thus obtaining a saturated calcium acetate solution.

[0046] The actual usage process and performance testing process of this embodiment are the same as those of Embodiment 1.

[0047] Example 3

[0048] A method for adsorption, sequestration, and flame retardancy of carbon dioxide in mines includes the following steps:

[0049] Steps S1 and S3 are the same as in Example 1, except for step S2;

[0050] S2. Preparation of sealed carbon-fixing flame retardant material: The prepared mineralized bacterial solution and saturated calcium acetate solution are mixed to obtain sealed carbon-fixing flame retardant material;

[0051] The pH value was adjusted to 8.5 during the preparation of the mineralized bacterial solution, and the other processes were the same as in Example 1;

[0052] The preparation process of the saturated calcium acetate solution is the same as in Example 2.

[0053] The actual usage process and performance testing process of this embodiment are the same as those of Embodiment 1.

[0054] Example 4

[0055] A method for adsorption, sequestration, and flame retardancy of carbon dioxide in mines includes the following steps:

[0056] Steps S1 and S3 are the same as in Example 1, except for step S2;

[0057] S2. Preparation of sealed carbon-fixing flame retardant material: The prepared mineralized bacterial solution and saturated calcium acetate solution are mixed to obtain sealed carbon-fixing flame retardant material;

[0058] The mineralizing bacterial solution was cultured for 60 hours, and the other processes were the same as in Example 1.

[0059] The preparation process of the saturated calcium acetate solution is the same as in Example 2.

[0060] The actual usage process and performance testing process of this embodiment are the same as those of Embodiment 1.

[0061] Example 5

[0062] A method for adsorption, sequestration, and flame retardancy of carbon dioxide in mines includes the following steps:

[0063] Steps S1 and S3 are the same as in Example 1, except for step S2;

[0064] S2. Preparation of sealed carbon-fixing flame retardant material: The prepared mineralized bacterial solution and saturated calcium acetate solution are mixed to obtain sealed carbon-fixing flame retardant material;

[0065] In the preparation of the mineralizing bacterial solution, the incubation time was 36 hours, and the other processes were the same as in Example 1;

[0066] The preparation process of the saturated calcium acetate solution is the same as in Example 2.

[0067] The usage and performance testing process of this embodiment are the same as those of Embodiment 1.

[0068] Example 6

[0069] A method for adsorption, sequestration, and flame retardancy of carbon dioxide in mines includes the following steps:

[0070] Steps S1 and S3 are the same as in Example 1, except for step S2;

[0071] S2. Preparation of sealed carbon-fixed flame retardant material: The prepared mineralized bacterial solution and saturated CaCl2 solution are mixed to obtain sealed carbon-fixed flame retardant material;

[0072] In the preparation of the mineralizing bacterial solution, the culture time was 60 hours, and the other processes were the same as in Example 1;

[0073] The preparation process of the saturated CaCl2 solution is the same as in Example 1.

[0074] The actual usage process and performance testing process of this embodiment are the same as those of Embodiment 1.

[0075] Example 7

[0076] A method for adsorption, sequestration, and flame retardancy of carbon dioxide in mines includes the following steps:

[0077] Steps S1 and S3 are the same as in Example 1, except for step S2;

[0078] S2. Preparation of sealed carbon-fixed flame retardant material: The prepared mineralized bacterial solution and saturated CaCl2 solution are mixed to obtain sealed carbon-fixed flame retardant material;

[0079] During the preparation of the mineralized bacterial solution, the pH value was adjusted to 8.5, and the other processes were the same as in Example 1;

[0080] The preparation process of the saturated CaCl2 solution is the same as in Example 1.

[0081] The actual usage process and performance testing process of this embodiment are the same as those of Embodiment 1.

[0082] Example 8

[0083] A method for adsorption, sequestration, and flame retardancy of carbon dioxide in mines, the method being the same as in Example 1.

[0084] The performance testing process in this embodiment is the same as that in Embodiment 1.

[0085] In use, the adsorbent material is precisely and evenly sprayed onto the carbon dioxide accumulation area in the mine and left to stand for 5 hours to ensure sufficient adsorption of CO2 from the environment. The carbon-fixing flame retardant material is then sprayed onto the CO2-adsorbed area. Upon contact with the coal, the carbon-fixing flame retardant material further generates a dense calcium carbonate layer, filling the pores of the coal and preventing the diffusion of oxygen and CO2. Simultaneously, it converts some of the adsorbed CO2 into stable carbonates, preventing desorption. Experiments have proven that the carbon-fixing flame retardant material used in this invention can inhibit coal oxidation reactions and reduce the risk of spontaneous combustion.

[0086] Example 9

[0087] A method for adsorption, sequestration, and flame retardancy of carbon dioxide in mines, the method being the same as in Example 1.

[0088] The performance testing process in this embodiment is the same as that in Embodiment 1.

[0089] In use, the adsorbent material is precisely and evenly sprayed onto the carbon dioxide accumulation area in the mine and left to stand for 1 hour to ensure sufficient adsorption of CO2 from the environment. The carbon-fixing flame retardant material is then sprayed onto the CO2-adsorbed area. Upon contact with the coal, the carbon-fixing flame retardant material further generates a dense calcium carbonate layer, filling the pores of the coal and preventing the diffusion of oxygen and CO2. Simultaneously, it converts some of the adsorbed CO2 into stable carbonates, preventing desorption. Experiments have proven that the carbon-fixing flame retardant material used in this invention can inhibit coal oxidation reactions and reduce the risk of spontaneous combustion.

[0090] Comparative Example 1

[0091] A method for adsorbing carbon dioxide in mines, wherein the method includes only step S1 of Example 1.

[0092] The performance testing process in this embodiment is the same as that in Embodiment 1.

[0093] When using, the adsorbent material is precisely sprayed and evenly applied to the carbon dioxide accumulation area in the mine, and left to stand for 2 hours to ensure that it fully adsorbs CO2 in the environment.

[0094] Comparative Example 2

[0095] Take 10g of raw coal sample and grind it manually to 40 mesh; place the sample in an oven at 40℃ and dry for 12 hours to prepare sample No. 11. The performance testing process is the same as in Example 1.

[0096] Coal samples treated in Examples 1-9 were designated as Samples 1-9, coal sample treated in Comparative Example 1 was designated as Sample 10, and sample prepared in Comparative Example 2 was designated as Sample 11.

[0097] The above samples were subjected to adsorption and carbon fixation effect tests, pore characteristics tests (77K nitrogen adsorption-desorption experiment), and flame retardant performance tests (oxidation process experiment), respectively. The results are as follows: Figures 1-3 As shown.

[0098] 1. From Figure 1 It can be seen from this:

[0099] (1) Differences in carbon-fixing flame retardant materials

[0100] In Examples 2-5, the adsorbent was ZIF-8 derived porous carbon dispersion, but the carbon fixation flame retardant was a saturated calcium acetate solution. In Examples 1 and 6-9, the adsorbent was a saturated CaCl2 solution, which varied due to the different calcium salt solutions used and the different preparation conditions (pH value, culture time) of the mineralizing bacteria solution. The products generated by the reaction of different carbon fixation flame retardant materials (saturated CaCl2 solution and saturated calcium acetate solution) with the mineralizing bacteria solution may have differences in structure and performance, thus affecting the CO2 fixation effect. The density and pore structure of the generated calcium carbonate precipitate layer are different, which will lead to different CO2 adsorption and desorption amounts, thus affecting the CO2 concentration. It can be compared that, under the same culture conditions, calcium chloride is more effective as a calcium source than calcium acetate solution.

[0101] The pH value and culture time were variables in the preparation of the mineralized bacterial solution. In different embodiments, the pH value was adjusted from 6.5 to 8.5, and the culture time varied between 36 and 60 hours. These conditions affected the growth and activity of *Pasteurella multocida*. Under the same calcium source, a pH value of 6.5 (Example 2) was more conducive to certain metabolic activities of the bacteria, resulting in better adsorption and fixation of CO2 by the generated carbon-fixing flame retardant material, thus leading to relatively low CO2 concentrations after adsorption and desorption. Regarding the culture time, 48 hours was the optimal time for bacterial culture.

[0102] (2) Effects of adsorption and reaction time

[0103] Examples 1, 2, 3, 4, 5, 6, and 7 had a settling time of 2 hours for CO2 adsorption, Example 8 had a settling time of 5 hours, and Example 9 had a settling time of 1 hour. Examples 1, 8, and 9 had identical preparation conditions, differing only in settling time. Experimental results showed that theoretically, the longer the settling time before adsorption saturation, the more CO2 was adsorbed. After equilibrium was reached, further increasing the settling time did not significantly increase the adsorption capacity. For example, in Example 9, the settling time of 1 hour was too short, and CO2 adsorption in the environment did not reach saturation. In contrast, Example 8 had an adsorption time of 5 hours, but the change in CO2 adsorption was minimal compared to the 2-hour adsorption time (Example 1). Therefore, considering the time cost of application, an adsorption time of 2 hours was selected as the standard application time for materials in production.

[0104] (3) Differences between different treatment methods

[0105] Comparative Example 2 (sample 11) is a raw coal sample that has not undergone any adsorption or carbon fixation treatment. Its inherent capacity for CO2 adsorption and fixation is limited, resulting in relatively high CO2 concentrations after both adsorption and desorption. Comparative Example 1 (sample 10) only has an adsorption step and lacks a carbon fixation step. Compared to the examples with complete adsorption and carbon fixation processes, its CO2 fixation effect is poor, leading to greater CO2 release during desorption and consequently, a higher CO2 concentration after desorption.

[0106] 2. From Figure 2 It can be seen from this:

[0107] The average pore size, from largest to smallest, is 10 (Comparative Example 1), 11 (Comparative Example 2), Example 2, Example 5, Example 7, Example 3, Example 4, Example 9, Example 8, Example 1, and Example 6. This indicates that the samples treated in different examples and comparative examples have different pore structures, and the change in pore size can reflect the adsorption and carbon fixation capacity of the samples to a certain extent.

[0108] Comparative Example 1 only involved spraying the adsorbent material, using ZIF-8 derived porous carbon dispersion as the adsorbent, mixed with activated carbon and polyvinylidene fluoride in a specific ratio. Substances present in the coal dissolved in the adsorbent material, resulting in an increase in pore size.

[0109] Comparative Example 2 is a raw coal sample, without these adsorbent materials. It has a larger average pore size compared to Example 1.

[0110] Pore ​​size indirectly reflects the material's sealing effect on coal. The sealing effect is comprehensively affected by the cultivation formula of the carbon-fixing flame-retardant material and the reaction time. The difference between Examples 2, 3, 4, and 5 and Example 1 is that the calcium source used is calcium acetate, and Example 4 has the longest cultivation time, reaching 60 hours. The cultivation environment pH of Example 3 is 8.5, but the sealing effect is weaker than that of Example 1. This indicates that calcium chloride has an absolute advantage over calcium acetate in the selection of calcium source. Moreover, when the cultivation time is within 60 hours, the time and the sealing effect are positively correlated. This can be seen from Examples 1 and 6, and Examples 4 and 5. Through experimental observation, it was found that when the cultivation time is extended to 60 hours, the improvement in sealing effect compared to a cultivation time of 48 hours is much smaller than that when the cultivation time is extended from 36 hours to 48 hours. Therefore, considering the actual production cost, a cultivation time of 48 hours is selected as the comprehensive optimal cultivation time. A comparison of Examples 2 and 3, and Examples 1 and 8, shows that under a unified calcium source, different pH values ​​affect the growth and metabolic activities of *Bacillus pasteurellii*, thereby influencing the effect of its produced substances on pores. At a pH of 6.5, bacterial reproduction is better, more metabolic products are produced, and the reaction with the abundant calcium source in the environment generates more calcium carbonate, resulting in a smaller average pore size.

[0111] 3. From Figure 3It can be seen from this:

[0112] Example 1 employs the mine carbon dioxide adsorption-sealage and flame retardant method of the present invention. Comparative Example 1 (No. 10) only includes the adsorption step in Example 1, while Comparative Example 2 (No. 11) has a simpler treatment method, does not use specific adsorption materials and carbon-fixing flame retardant materials, basically maintains the original state of the raw coal, and only performs simple physical treatment.

[0113] Below 80℃, the oxygen consumption curves of the three samples were similar. When the temperature rose to 120℃, a large number of active groups participated in the reaction, and the oxygen consumption and oxygen consumption rate increased significantly. In Example 1, due to the reduced concentration of oxygen participating in the reaction caused by the surface calcium carbonate adhesion, and the effective inhibition of active functional groups in the coal from participating in the oxidation reaction by the flame retardant material, the oxygen consumption rate only increased rapidly at 120℃, which was 10℃ later than that of the original coal, and the increase was relatively slow. In Comparative Example 1, since it was not subjected to inhibition treatment, the oxygen consumption rate was similar to that of the original coal, and at 200℃, all three groups of oxygen were completely consumed.

Claims

1. A method for adsorption, sequestration, and flame retardancy of carbon dioxide in mines, characterized in that, Includes the following steps: S1. Preparation of porous carbon dispersion derived from ZIF-8 carbon dioxide adsorption coating; S2. Preparation of sealed carbon-fixing flame retardant material: The prepared mineralized bacterial solution and saturated CaCl2 solution / saturated calcium acetate solution are mixed to obtain sealed carbon-fixing flame retardant material; S3. The carbon dioxide adsorption coating ZIF-8 derived porous carbon dispersion prepared in step S1 is uniformly coated on the surface of the coal sample in the carbon dioxide accumulation area of ​​the mine. After standing for a period of time, the coal sample fully adsorbs carbon dioxide in the underground environment. Then, the carbon sequestration and flame retardant material prepared in step S2 is sprayed on the surface of the coal sample to generate a calcium carbonate precipitation layer, thereby achieving carbon dioxide adsorption and sequestration and pore sealing in the goaf. The specific process of step S1 is as follows: S1-1. Prepare 2-methylimidazole solution and zinc nitrate solution separately, mix them in equal volumes and stir until clear, let stand and filter to obtain white precipitate; then wash the white precipitate with alcohol and dry to obtain ZIF-8 powder. S1-2. ZIF-8 powder was carbonized under N2 atmosphere, and then repeatedly washed with dilute hydrochloric acid and deionized water and dried to obtain ZIF-8 derived porous carbon. S1-3. Mix ZIF-8 derived porous carbon, activated carbon, and polyvinylidene fluoride, add N,N-dimethylacetamide, and stir to mix evenly to obtain a black slurry, which is the ZIF-8 derived porous carbon dispersion for carbon dioxide adsorption coating.

2. The method for adsorption, sequestration, and flame retardancy of carbon dioxide in mines according to claim 1, characterized in that, In step S1-1, the concentration of the 2-methylimidazole solution is 0.8 mol / L and the concentration of the zinc nitrate solution is 0.15 mol / L; in steps 1-3, the mass ratio of ZIF-8 derived porous carbon, activated carbon, and polyvinylidene fluoride is 9:1:

1.

3. The method for adsorption, sequestration, and flame retardancy of carbon dioxide in mines according to claim 1, characterized in that, In step S2, the preparation process of the mineralized bacterial solution is as follows: beef extract and peptone are mixed in a sterilized container filled with distilled water and stirred until completely dissolved. The mixture is then allowed to stand at room temperature to obtain the basic culture medium. After adjusting the pH of the basic culture medium to 6.5-8.5, urea solution is added to the culture medium to make the urea concentration reach 25 g / L. The culture medium is then sterilized at high temperature in an autoclave and inoculated with Bacillus pasteurellii. The inoculated culture medium is then placed in a constant temperature shaker and cultured at 25°C and 180 r / min for 36-60 h to obtain the mineralized bacterial solution.

4. The method for adsorption, sequestration, and flame retardancy of carbon dioxide in mines according to claim 1, characterized in that, In step S2, the mineralized bacterial solution is mixed with saturated CaCl2 solution / saturated calcium acetate solution at a volume ratio of 1:1 to obtain the sealed carbon-fixing flame retardant material.

Images