Mine carbon dioxide adsorption, storage and flame retardant method

Abstract

The invention discloses a carbon dioxide adsorption, storage and flame retardant method for a mine. The method comprises the following steps: preparing a carbon dioxide adsorption coating ZIF-8 derived porous carbon dispersion liquid; preparing a sealed carbon-sequestration flame-retardant material: mixing the prepared mineralized bacteria solution and the saturated CaCl2 solution / saturated calcium acetate solution to obtain the sealed carbon-sequestration flame-retardant material; the method comprises the following steps: uniformly coating a carbon dioxide adsorption coating ZIF-8 derived porous carbon dispersion liquid on the surface of a coal sample in a mine carbon dioxide gathering area, standing for a period of time, and after the treated coal sample fully adsorbs carbon dioxide in an underground environment, spraying a sealed carbon sequestration flame-retardant material on the surface of the coal sample to generate a calcium carbonate precipitation layer; carbon dioxide adsorption and sealing and pore plugging of the goaf are realized. According to the invention, stable carbon sequestration and storage of carbon dioxide in the underground goaf of the mine can be realized, the spontaneous combustion phenomenon of underground coal is effectively inhibited, and the underground CO2 emission is fundamentally reduced.

Description

Technical Field

[0001] The present invention relates to the field of underground carbon fixation, flame retardancy and carbon dioxide adsorption and storage technology, and in particular to a mine carbon dioxide adsorption and storage and flame retardancy method, which has important applications in mine gas adsorption, spontaneous combustion suppression, safety protection and greenhouse gas control. Background Art

[0002] CO2 adsorption and storage (CCS) technology has attracted significant attention in the industrial, energy, and mining sectors as an effective means of reducing greenhouse gas emissions into the atmosphere. Coal mines, as a key area of greenhouse gas emissions, face severe pressure to reduce CO2 emissions. Frequent spontaneous combustion of coal underground not only poses a serious threat to mine safety and production, resulting in significant waste of resources, but also generates large amounts of CO2, which is released into the atmosphere, further exacerbating the greenhouse effect.

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

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

[0005] The purpose of the present invention is to provide a method for adsorption, storage and flame retardancy of carbon dioxide in mines, which can achieve stable carbon fixation and storage of carbon dioxide in the goaf of mines, while effectively inhibiting the spontaneous combustion of coal underground, and 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, preparing a ZIF-8 derived porous carbon dispersion for carbon dioxide adsorption coating;

[0008] S2. Preparing a sealing and carbon-fixing flame-retardant material: mixing the prepared mineralized bacterial solution and a saturated CaCl2 solution / saturated calcium acetate solution to obtain a sealing and carbon-fixing flame-retardant material;

[0009] S3. Uniformly coat the ZIF-8-derived porous carbon dispersion of the carbon dioxide adsorption coating prepared in step S1 on the surface of the coal sample in the carbon dioxide aggregation area of the mine. Let it stand for a period of time. After the treated coal sample has fully adsorbed carbon dioxide in the underground environment, then spray the carbon sequestration and flame retardant material prepared in step S2 on the surface of the coal sample to form a calcium carbonate precipitation layer, realizing carbon dioxide adsorption and sequestration and pore plugging in the goaf.

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

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

[0012] S1-2. Carbonize the ZIF-8 powder under N2 atmosphere, and repeatedly wash it with dilute hydrochloric acid and deionized water and then dry it to obtain ZIF-8-derived porous carbon;

[0013] S1-3. Mix the ZIF-8-derived porous carbon, activated carbon, and polyvinylidene fluoride, add N,N-dimethylacetamide, and stir and mix evenly to obtain a black slurry, which is the ZIF-8-derived porous carbon dispersion of the 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 step 1-3, the mass ratio of the ZIF-8-derived porous carbon, activated carbon, and polyvinylidene fluoride is 9:1:1.

[0015] Further, in step S2, the preparation process of the mineralization bacterial solution is as follows: Mix beef extract and peptone in a sterilized container containing distilled water, stir evenly until completely dissolved, and let it stand at room temperature to obtain a basal medium; after adjusting the pH of the basal medium to 6.5-8.5, add a urea solution to the medium to make the urea concentration reach 25 g / L; perform high-temperature sterilization treatment on the medium in an autoclave, and then inoculate Sporosarcina pasteurii; place the inoculated medium in a constant temperature shaker and culture it at a temperature of 25 °C and a rotation speed of 180 r / min for 36-60 h to obtain the mineralization bacterial solution.

[0016] Preferably, in step S2, the mineralization bacterial solution and the saturated CaCl2 solution / saturated calcium acetate solution are mixed at a volume ratio of 1:1 to obtain the carbon sequestration and flame retardant material.

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

[0018] (1) In the present 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 carbon dioxide adsorption amount, and has the ability to efficiently adsorb carbon dioxide in the mine environment. The sequestration material can not only sequester the adsorbed carbon dioxide, but also physically reinforce and flame-retard the goaf; in addition, the sequestration material uses biological materials, which are green and environmentally friendly, and avoid the secondary pollution that traditional chemical materials may bring to the environment while sequestering carbon dioxide;

[0019] In summary, the present invention introduces MOFs-derived materials into the mine environment and realizes carbon fixation through their efficient adsorption ability. 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. The present invention also combines the carbon fixation function of ZIF-8-derived porous carbon with the flame-retardant and oxygen-isolating functions of the MICP technology, and sprays the sequestration carbon fixation flame-retardant material to generate a calcium carbonate precipitation layer, which not only realizes the stable carbon fixation and sequestration of carbon dioxide, but also can inhibit the spontaneous combustion of coal underground, solving the dual needs of carbon dioxide capture and coal spontaneous combustion prevention in the mine, thereby improving the safety and environmental protection benefits of the mine. Brief Description of the Drawings

[0020] Figure 1 Schematic diagram of CO2 adsorption and desorption of each embodiment and comparative example of the present invention;

[0021] Figure 2 Statistical chart of average pore size of each embodiment and comparative example of the present invention;

[0022] Figure 3 Schematic diagram of the oxidation process of Example 1, Comparative Example 1, and Comparative Example 2 of the present invention. Detailed Description of the Invention

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

[0024] Example 1

[0025] A method for adsorbing, sequestering and flame-retarding carbon dioxide in a mine, comprising the following steps:

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

[0027] S1-1. In a 1-L beaker, mix 400 mL of 2-methylimidazole solution with a concentration of 0.8 mol / L and 400 mL of zinc nitrate solution with a concentration of 0.15 mol / L, and continuously stir until the solution becomes clear and transparent. Subsequently, let the mixed solution stand for 12 hours. After the white precipitate is completely crystallized, perform suction filtration. The collected white precipitate is rinsed with alcohol to remove impurities, and then placed in an oven to dry to obtain ZIF-8 powder.

[0028] S1-2. Place the ZIF-8 powder under a nitrogen atmosphere and carry out carbonization treatment at a high temperature of 600 °C for 4 hours. After carbonization is completed, repeatedly wash the product with dilute hydrochloric acid (pH < 3) to remove residual impurities. Finally, dry the washed product 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 in a mass ratio of 9:1:1, add 5 mL of N,N-dimethylacetamide, and stir and mix evenly to obtain a black slurry, which is the ZIF-8-derived porous carbon dispersion of the carbon dioxide adsorption coating.

[0030] S2. Prepare the sequestration carbon-fixing and flame-retardant material: Mix the prepared mineralized bacterial solution and saturated CaCl2 solution to obtain the sequestration carbon-fixing and flame-retardant material.

[0031] The preparation process of the mineralized bacterial solution is as follows: Add 3 g of beef extract and 5 g of peptone to 1000 mL of distilled water, stir until completely dissolved to obtain the basal medium. Use NaOH solution to adjust the pH value of the medium to 7.5. Then add urea solution to the medium to make the urea concentration reach 25 g / L. After the medium is subjected to high-temperature sterilization treatment in an autoclave, inoculate Sporosarcina pasteurii. Place the inoculated medium in a constant-temperature shaker and culture it at a temperature of 25 °C and a rotation speed of 180 r / min for 48 hours to obtain the mineralized bacterial solution.

[0032] The preparation process of the saturated CaCl2 solution is as follows: Dissolve calcium chloride in distilled water until it reaches a saturated state to obtain the saturated CaCl2 solution.

[0033] S3. Uniformly coat the ZIF-8-derived porous carbon dispersion of the carbon dioxide adsorption coating prepared in step S1 on the surface of the coal sample in the carbon dioxide aggregation area of the mine, and let it stand for 2 h. After the treated coal sample fully adsorbs carbon dioxide in the underground environment, then spray the sequestration carbon-fixing and flame-retardant material prepared in step S2 on the surface of the coal sample to form a calcium carbonate precipitation layer, realizing carbon dioxide adsorption and sequestration and pore plugging in the goaf.

[0034] In use, the adsorption material is precisely and evenly sprayed and coated on the area where carbon dioxide accumulates in the mine, and left standing for more than 2 hours to ensure that it fully adsorbs CO2 in the environment. The carbon sequestration and flame retardant material is sprayed onto the area that has adsorbed CO2. After the carbon sequestration and flame retardant material contacts the coal body, a dense calcium carbonate layer is further formed to fill the pores of the coal body, isolate the diffusion of oxygen and CO2, and at the same time convert part of the adsorbed CO2 into stable carbonate to prevent desorption. The carbon sequestration and flame retardant material used in this invention has been experimentally proven to be able to inhibit the oxidation reaction of the coal body and reduce the risk of spontaneous combustion.

[0035] Performance test process:

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

[0037] Turn on the gas supply system, introduce carbon dioxide into the sealed simulated roadway. There are 5000 g of lump coal with a particle size of 3 - 5 cm piled up in the roadway. After the CO2 concentration in the roadway is stable (fluctuation ≤ 5%), start the control valve of the first liquid storage tank, evenly spray the adsorption material on the roadway surface (coverage rate ≥ 95%), and leave it standing for 2 hours. During this period, record the change of CO2 concentration in the roadway every half hour. After 2 hours, when the carbon dioxide concentration is monitored to decrease to a stable level, synchronously spray the sealed carbon sequestration and flame retardant material on the roadway surface, and after completion, leave it standing for 2 hours to wait for the material to fully act; then connect the gas chromatograph instrument, introduce argon, and purge the treated area, untreated area, and the adsorption and non-carbon sequestration area where only the adsorption material is sprayed after spraying the adsorption material and carbon sequestration material respectively. Analyze and compare the change of gas concentration.

[0038] 2. Pore characteristic test (77K nitrogen adsorption and desorption experiment): Take 10 g of 40 - mesh coal powder, after being treated with carbon dioxide adsorption coating and sealed carbon sequestration and flame retardant material respectively, put it into the 77K low - temperature nitrogen adsorption and desorption experimental device to conduct adsorption - desorption experiments and analyze the pore situation.

[0039] 3. Flame retardant performance test (oxidation process experiment): Put the prepared sample into the programmed temperature - rising device. Under the condition of an oxygen concentration of 20%, raise the temperature from room temperature to 200 degrees Celsius. Use a thermocouple and a thermogravimetric balance to obtain the thermogravimetric curve, and calculate the oxygen consumption rate of the sample with temperature change and the curve of oxygen concentration change with temperature.

[0040] Example 2

[0041] A method for adsorbing, sequestering and flame - retarding carbon dioxide in a mine, comprising the following steps:

[0042] Steps S1 and S3 are the same as those in Example 1, the difference lies in step S2;

[0043] S2. Prepare the sealed carbon sequestration and flame retardant material: Mix the prepared mineralization bacterial liquid and saturated calcium acetate solution to obtain the sealed carbon sequestration and flame retardant material;

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

[0045] The preparation process of the saturated calcium acetate solution is as follows: Dissolve calcium acetate in distilled water until it reaches a saturated state to obtain a saturated calcium acetate solution.

[0046] The usage process and performance test process of this example were the same as those in Example 1.

[0047] Example 3

[0048] A method for adsorbing, sequestering and flame-retarding carbon dioxide in a mine, comprising the following steps:

[0049] Steps S1 and S3 are the same as those in Example 1, and the difference lies in step S2;

[0050] S2. Prepare the sequestration carbon-fixing flame-retardant material: Mix the prepared mineralized bacterial solution and saturated calcium acetate solution to obtain the sequestration carbon-fixing flame-retardant material;

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

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

[0053] The usage process and performance test process of this example were the same as those in Example 1.

[0054] Example 4

[0055] A method for adsorbing, sequestering and flame-retarding carbon dioxide in a mine, comprising the following steps:

[0056] Steps S1 and S3 are the same as those in Example 1, and the difference lies in step S2;

[0057] S2. Prepare the sequestration carbon-fixing flame-retardant material: Mix the prepared mineralized bacterial solution and saturated calcium acetate solution to obtain the sequestration carbon-fixing flame-retardant material;

[0058] During the preparation of the mineralized bacterial solution, the culture time was 60 h, and other processes were the same as those in Example 1;

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

[0060] The usage process and performance test process of this example were the same as those in Example 1.

[0061] Example 5

[0062] A method for adsorbing, sequestering and flame-retarding carbon dioxide in a mine, comprising the following steps:

[0063] Steps S1 and S3 are the same as those in Example 1, with the difference lying in Step S2;

[0064] S2. Prepare the carbon sequestration and fire retardant material: Mix the prepared mineralized bacterial solution and saturated calcium acetate solution to obtain the carbon sequestration and fire retardant material;

[0065] During the preparation of the mineralized bacterial solution, the cultivation time is 36 h, and other processes are the same as those in Example 1;

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

[0067] The usage process and performance test process of this example are both the same as those in Example 1.

[0068] Example 6

[0069] A method for adsorbing, sequestering and retarding fire of carbon dioxide in a mine, comprising the following steps:

[0070] Steps S1 and S3 are the same as those in Example 1, with the difference lying in Step S2;

[0071] S2. Prepare the carbon sequestration and fire retardant material: Mix the prepared mineralized bacterial solution and saturated CaCl2 solution to obtain the carbon sequestration and fire retardant material;

[0072] During the preparation of the mineralized bacterial solution, the cultivation time is 60 h, and other processes are the same as those in Example 1;

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

[0074] The usage process and performance test process of this example are both the same as those in Example 1.

[0075] Example 7

[0076] A method for adsorbing, sequestering and retarding fire of carbon dioxide in a mine, comprising the following steps:

[0077] Steps S1 and S3 are the same as those in Example 1, with the difference lying in Step S2;

[0078] S2. Prepare the carbon sequestration and fire retardant material: Mix the prepared mineralized bacterial solution and saturated CaCl2 solution to obtain the carbon sequestration and fire retardant material;

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

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

[0081] The usage process and performance test process of this example are both the same as those in Example 1.

[0082] Example 8

[0083] A method for adsorbing, sequestering and flame-retarding carbon dioxide in a mine, which is the same as that in Example 1.

[0084] The performance test process of this example is the same as that in Example 1.

[0085] During use, the adsorption material is accurately sprayed and evenly coated on the carbon dioxide aggregation area in the mine, and left standing for 5 hours to ensure that it fully adsorbs CO2 in the environment; the carbon sequestration and flame-retarding material is sprayed onto the area where CO2 has been adsorbed; after the carbon sequestration and flame-retarding material contacts the coal body, a dense calcium carbonate layer is further formed to fill the pores of the coal body, isolate the diffusion of oxygen and CO2, and at the same time convert part of the adsorbed CO2 into stable carbonate to prevent desorption. The carbon sequestration and flame-retarding material used in this invention has been experimentally proven to be able to inhibit the oxidation reaction of the coal body and reduce the risk of spontaneous combustion.

[0086] Example 9

[0087] A method for adsorbing, sequestering and flame-retarding carbon dioxide in a mine, which is the same as that in Example 1.

[0088] The performance test process of this example is the same as that in Example 1.

[0089] During use, the adsorption material is accurately sprayed and evenly coated on the carbon dioxide aggregation area in the mine, and left standing for 1 hour to ensure that it fully adsorbs CO2 in the environment. The carbon sequestration and flame-retarding material is sprayed onto the area where CO2 has been adsorbed; after the carbon sequestration and flame-retarding material contacts the coal body, a dense calcium carbonate layer is further formed to fill the pores of the coal body, isolate the diffusion of oxygen and CO2, and at the same time convert part of the adsorbed CO2 into stable carbonate to prevent desorption. The carbon sequestration and flame-retarding material used in this invention has been experimentally proven to be able to inhibit the oxidation reaction of the coal body and reduce the risk of spontaneous combustion.

[0090] Comparative Example 1

[0091] A method for adsorbing carbon dioxide in a mine, which only includes step S1 in Example 1.

[0092] The performance test process of this example is the same as that in Example 1.

[0093] During use, the adsorption material is accurately sprayed and evenly coated on the carbon dioxide aggregation area in the mine, and left standing for 2 hours to ensure that it fully adsorbs CO2 in the environment.

[0094] Comparative Example 2

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

[0096] Take the coal samples after being treated in Examples 1 - 9 as Sample Nos. 1 - 9, the coal sample after being treated in Comparative Example 1 as No. 10, and the sample prepared in Comparative Example 2 as No. 11.

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

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

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

[0100] In Examples 2 - 5, the adsorption material is ZIF - 8 - derived porous carbon dispersion, but the carbon - sequestration and flame - retardant material is saturated calcium acetate solution; in Examples 1, 6 - 9, it is saturated CaCl2 solution, which is different due to the different calcium salt solutions used and the preparation conditions (pH value, culture time) of the mineralization bacterial solution. The products formed by the reaction of different carbon - sequestration and flame - retardant materials (saturated CaCl2 solution and saturated calcium acetate solution) with the mineralization bacterial solution may have differences in structure and performance, thus affecting the CO2 fixation effect. The density and pore structure of the generated calcium carbonate precipitation layer are different, resulting in different CO2 adsorption and desorption amounts, and further affecting the CO2 concentration. It can be compared that under the same culture conditions, calcium chloride as the calcium source has a better effect than calcium acetate solution.

[0101] The pH value and culture time in the process of preparing the mineralization bacterial solution are variables. In different examples, the pH value adjustment range is 6.5 - 8.5, and the culture time varies between 36h - 60h. These conditions will affect the growth and activity of Sporosarcina pasteurii. Under the same calcium source, when the pH value is 6.5 (Example 2), it is more conducive to certain metabolic activities of the bacteria, making the generated carbon - sequestration and flame - retardant material have better CO2 adsorption and fixation effects, so that the CO2 concentration after adsorption and after purging and desorption is relatively low. In terms of the culture time, 48 hours is the best time for bacterial culture.

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

[0103] In Examples 1, 2, 3, 4, 5, 6, and 7, the standing time is 2 hours when adsorbing CO2. In Example 8, the standing time is 5 hours, and in Example 9, the standing time is 1 hour. Among them, Examples 1, 8, and 9 have exactly the same preparation conditions, only the standing time is different. From the experimental results, it can be seen that before adsorption saturation, the longer the standing time, the more CO2 is theoretically adsorbed. After reaching equilibrium, increasing the time will not significantly increase the adsorption amount. For example, in Example 9 with a standing time of 1 hour, the adsorption time is too short, and the CO2 in the environment has not reached saturation during adsorption. While in Example 8 with an adsorption time of up to 5 hours, compared with the adsorption time of 2 hours (Example 1), the change in the CO2 adsorption amount is extremely small. Therefore, considering the application time cost, an adsorption time of 2 hours is selected as the standard application time for materials during production work.

[0104] (3) Differences in different treatment methods

[0105] Control Example 2 (Sample No. 11) is a raw coal sample without any adsorption and carbon fixation treatment. Its ability to adsorb and fix CO2 is limited, so the CO2 concentration is relatively high after adsorption and after purge desorption. Control Example 1 (Sample No. 10) only has an adsorption step and no carbon fixation step. Compared with the Examples with a complete adsorption and carbon fixation process, its CO2 fixation effect is poor, and more CO2 is released during desorption, resulting in a relatively high CO2 concentration after purge desorption.

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

[0107] The average pore diameter decreases in the order of 10 (Control Example 1), 11 (Control Example 2), Example 2, Example 5, Example 7, Example 3, Example 4, Example 9, Example 8, Example 1, Example 6. This shows that there are differences in the pore structures of the samples treated in different Examples and Control Examples, and the change in pore size can reflect the sample's adsorption and carbon fixation abilities to a certain extent.

[0108] In Control Example 1, only the adsorption material was sprayed, and the ZIF-8-derived porous carbon dispersion was used as the adsorption material, which was mixed with activated carbon and polyvinylidene fluoride in a specific ratio. The substances existing in the coal dissolve in the adsorption material, resulting in an increase in the pore diameter.

[0109] Control Example 2 is a raw coal sample without using these adsorption materials. Its average pore diameter is larger than that of Example 1.

[0110] The pore size indirectly reflects the plugging effect of the material on the coal body. The plugging effect is comprehensively affected by the cultivation formula of the carbon sequestration and flame retardant material and the reaction time. The differences between Examples 2, 3, 4, and 5 and Example 1 are that the calcium source used is calcium acetate, and the cultivation time of Example 4 is the longest, reaching 60 h. The pH value of the cultivation environment of Example 3 is 8.5. However, the plugging effects of all of them are weaker than that of Example 1, indicating that calcium chloride has an absolute advantage over calcium acetate in terms of calcium source selection. When the cultivation duration is within 60 h, the duration is positively correlated with the plugging effect. This can be seen from Example 1 and Example 6; Example 4 and Example 5. Through experimental observation, when the cultivation time is extended to 60 h, the improvement amplitude of the plugging effect compared to the cultivation time of 48 h is much smaller than that from 36 h to 48 h. Therefore, considering the actual production cost, the cultivation time of 48 h is selected as the comprehensive optimal cultivation duration. By comparing Example 2 with Example 3, and Example 1 with Example 8, it can be known that under the same calcium source, different pH values will affect the growth and metabolic activities of Sporosarcina pasteurii, and thus affect the effect of the substances produced by it on the pores. When the pH value is 6.5, the bacteria reproduce better, and there are more metabolites, which react with the sufficient calcium source in the environment to generate more calcium carbonate, resulting in a smaller average pore size.

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

[0112] Example 1 adopts the method for adsorbing, sequestering and retarding combustion of mine carbon dioxide of the present invention. Comparative Example 1 (No. 10) only includes the adsorption step in Example 1. The treatment method of Comparative Example 2 (No. 11) is simple, without using specific adsorption materials and carbon sequestration and flame retardant materials, basically maintaining the original state of the raw coal, and only performing simple physical treatment.

[0113] Below 80 °C, the oxygen consumption curves of the three samples are approximately the same. When the temperature rises to 120 °C, a large number of active groups participate in the reaction, and the oxygen consumption and oxygen consumption rate increase significantly. In Example 1, the attachment of calcium carbonate on the surface layer reduces the concentration of oxygen participating in the reaction, and the flame retardant material effectively inhibits the participation of active functional groups in coal in the oxidation reaction. The oxygen consumption rate only rises rapidly at 120 °C, 10 °C later than that of the raw coal, and the increase is relatively slow; since Comparative Example 1 is not inhibited, its oxygen consumption rate is approximately the same as that of the raw coal. At 200 °C, all the oxygen in the three groups is consumed.

Claims

1. A method for carbon dioxide adsorption, storage and flame retardancy in a mine, characterized in that, It includes the following steps: S1. Prepare a carbon dioxide adsorption coating ZIF-8-derived porous carbon dispersion; S2. Prepare a carbon sequestration and fire retardant material: Mix the prepared mineralization bacterial solution and saturated CaCl2 solution / saturated calcium acetate solution to obtain the carbon sequestration and fire retardant material; S3. Uniformly coat the carbon dioxide adsorption coating ZIF-8-derived porous carbon dispersion prepared in step S1 on the surface of the coal sample in the carbon dioxide aggregation area of the mine. Let it stand for a period of time. After the treated coal sample fully adsorbs carbon dioxide in the underground environment, then spray the carbon sequestration and fire retardant material prepared in step S2 on the surface of the coal sample to form a calcium carbonate precipitation layer, realizing carbon dioxide adsorption and sequestration and pore plugging in the goaf.

2. The method for adsorbing, storing and flame-retarding carbon dioxide in a mine according to claim 1, characterized in that, The specific process of step S1 is as follows: S1-1. Prepare 2-methylimidazole solution and zinc nitrate solution respectively, mix them in equal volume, stir until clear, and let it stand for suction filtration to obtain a white precipitate; then wash the white precipitate with alcohol and dry it to obtain ZIF-8 powder; S1-2. Carbonize the ZIF-8 powder under N2 atmosphere, and repeatedly wash it with dilute hydrochloric acid and deionized water and then dry it 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 and mix evenly to obtain a black paste, which is the carbon dioxide adsorption coating ZIF-8-derived porous carbon dispersion.

3. A method for adsorbing, storing and flame-retarding carbon dioxide in a mine according to claim 2, 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 step 1-3, the mass ratio of ZIF-8-derived porous carbon, activated carbon, and polyvinylidene fluoride is 9:1:

1.

4. A method for adsorbing, storing and flame-retarding carbon dioxide in a mine according to claim 1 or 2, characterized in that In step S2, the preparation process of the mineralization bacterial solution is as follows: Mix beef extract and peptone in a sterilized container containing distilled water, stir evenly until completely dissolved, and let it stand at room temperature to obtain a basal medium; after adjusting the pH of the basal medium to 6.5-8.5, add a urea solution to the medium to make the urea concentration reach 25 g / L; sterilize the medium in a high-pressure sterilizer at high temperature, and inoculate Sporosarcina pasteurii; place the inoculated medium in a constant temperature shaker and culture it at a temperature of 25 °C and a rotation speed of 180 r / min for 36-60 h to obtain the mineralization bacterial solution.

5. A method for adsorbing, storing and flame-retarding carbon dioxide in a mine according to claim 1 or 2, characterized in that In step S2, the mineralization bacterial solution and the saturated CaCl2 solution / saturated calcium acetate solution are mixed in a volume ratio of 1:1 to obtain the carbon sequestration and fire retardant material.

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