Method for segmentally solidifying and sealing carbon dioxide in gangue-based cemented filling body

Abstract

The invention discloses a method for segmentally solidifying and sealing carbon dioxide through a gangue-based cemented filling body, and belongs to the technical field of mine environment treatment and carbon capture and sealing. According to the method, mine waste gangue is used as a main raw material, and efficient sealing and storage of carbon dioxide (CO2) are achieved through specific physical and chemical treatment. Firstly, gangue, cement, fly ash and water are prepared in proportion; and stirring the prepared raw materials to prepare the gangue-based cemented filling body slurry. Then, CO2 gas is introduced into the prepared slurry, and stirring is carried out; and then, the prepared gangue-based cemented filling body slurry is conveyed to a filling working face from a preparation site. And after the filling body slurry is hardened, CO2 is injected into the filling body, and the final storage process of CO2 is completed. The method not only can effectively utilize mine wastes and reduce environmental pollution, but also can realize long-term storage of carbon dioxide, has the advantages of simplicity in operation, environmental friendliness and the like, and is suitable for industrial large-scale application.

Description

Technical Field

[0001] The present invention relates to the technical field of mine environmental management and carbon capture and storage, and in particular to a method for storing carbon dioxide by segmented solidification of a gangue-based cemented filling body combined with paste filling and CO2 storage. Background Art

[0002] In the past hundred years, the greenhouse effect caused by carbon dioxide emissions has been very prominent, which has had an adverse impact on human production and life. At the same time, with the continuous increase in global coal mining, the output of solid waste such as mine gangue has also increased. The stacking of these wastes not only occupies a large amount of land resources, but also may cause environmental pollution and ecological damage. In order to effectively solve these problems, the resource utilization of mine solid waste has become a research hotspot. Among them, paste filling technology, as a method of converting mine waste into useful resources, has been widely used in green mining.

[0003] Filling paste is a new type of gel filling material mainly composed of cement, fly ash and coal gangue. This material can react chemically with carbon dioxide, and can capture and store carbon dioxide when preparing the filling paste, combining the utilization of coal mine waste with carbon fixation. In addition, after the paste reaches the goaf, the hydration and solidification process will form tiny pores, which are excellent places for adsorbing carbon dioxide. At present, the research and filling mining technology for the application of coal mine waste to carbon dioxide storage is still in its early stages of development. For carbon dioxide sequestration, most of the methods are directly used to store CO2 in the filling body, and the research and application of segmented storage are relatively small, and negative carbon filling is still in the technical theory stage. Therefore, solving the actual method of segmented solidification and sealing of carbon dioxide in gangue-based cemented filling bodies is a major problem that needs to be solved on site. Summary of the invention

[0004] Technical problem: The purpose of the present invention is to provide a method for storing carbon dioxide by segmented solidification of gangue-based cemented filling bodies, which is simple to operate, environmentally friendly and can effectively store CO2.

[0005] Technical solution: A method for storing carbon dioxide by segmented solidification of gangue-based cemented filling bodies of the present invention is characterized by comprising the following steps:

[0006] Step S1, raw material ratio: first, according to the set mass percentage, coal gangue, cement, fly ash and water are mixed;

[0007] Step S2, slurry preparation: input the raw materials prepared in step S1 into a gas-liquid two-phase reaction monitoring closed device, perform deep stirring, and form a gangue-based cemented filling material;

[0008] Step S3, CO2 blending: During the stirring process of step S2, CO2 gas captured from the industrial flue gas is introduced into the gangue-based cementitious filling material by using a flue gas capture device and continued to be stirred to ensure that CO2 and the gangue-based cementitious filling material are fully mixed and reacted to form a uniformly dispersed gangue-based cementitious filling slurry;

[0009] Step S4, filling material transportation: the gangue-based cemented filling material slurry prepared in step S3 is continuously transported from the preparation site to the filling working surface through a pipeline or a dedicated filling material transportation system;

[0010] Step S5, backfill hardening and CO2 sealing: the gangue-based cemented backfill slurry undergoes a natural or accelerated hardening process at the filling working surface to form a gangue-based cemented backfill with expected mechanical properties; after the backfill slurry in the filling working surface is hardened, CO2 is injected into the gangue-based cemented backfill in the filling working surface through the gas injection pipeline to complete the final sealing process of CO2.

[0011] In step S1, the set mass percentages are: 45-55% for gangue, 15-25% for fly ash, 5-15% for cement, and 15-25% for water.

[0012] In step S1, during the mixing process, the raw materials are added to the mixer in batches for mixing, with large particles added first, small particles added second, and water added last, so as to reduce the influence of large particles on the mixing uniformity; all components are evenly dispersed to avoid uneven filling performance due to inconsistent local concentrations.

[0013] In step S2, during the mixing and stirring of the prepared raw materials to form the gangue-based cemented filling material, the consistency and fluidity of the slurry need to be closely monitored, and the proportion of the slurry is adjusted according to actual conditions to ensure that the consistency and fluidity of the slurry meet the filling process requirements.

[0014] In step S3, before the CO2 gas captured from industrial exhaust gas is introduced into the gangue-based cementitious filling material for continued stirring, the throttle valve of the gas-liquid two-phase reaction monitoring and sealing device is first adjusted to the minimum value, and then the CO2 gas tank is unscrewed to adjust the external pressure to 0.5MPa. At this time, the CO2 gas has been reduced in pressure by the pressure reducing valve, and then the motor is turned on to control the stirring speed to 50rad / s, and then the throttle valve is slowly unscrewed. At this time, the flow meter starts to read, and CO2 gas is introduced while stirring. When CO2 no longer reacts with the gangue-based cementitious filling material, CO2 is enriched in the pipeline and above the mixing tank until the pressure gauge value above the mixing tank is stable or the instantaneous flow reading of the flow meter is zero. At this time, the reaction of concrete and CO2 is completed, and the gangue-based cementitious filling material has been fully absorbed by CO2.

[0015] In step S4, during the continuous transportation from the preparation site to the filling work surface, the flow state of the slurry is monitored by sensors and monitoring equipment installed in the transportation pipeline to prevent the slurry from settling, segregating or over-thickening. The slurry ratio is adjusted according to actual conditions. If the slurry does not flow smoothly in the pipeline or is blocked, the amount of water needs to be increased. If the slurry settles too fast during transportation or segregates on the filling work surface, the amount of solid raw materials needs to be increased to ensure the fluidity and consistency of the slurry ratio and avoid excessive thickening, which affects the quality of the filling body and the final filling effect.

[0016] In step S5, after the filling slurry in the filling working surface is hardened, a large number of tiny pores are formed inside the gangue-based cemented filling body, and the cracks of the filling body are further developed under the action of the overlying rock strata, CO2 is injected again.

[0017] Beneficial effects: The method of segmented solidification and storage of carbon dioxide of the present invention combines carbon dioxide and mine waste to achieve carbon dioxide storage and increase the storage capacity. By accurately calculating the raw material ratio of the filling body, optimizing the slurry preparation process, and innovatively mixing CO2 in segments, a gangue-based cemented filling body with good mechanical properties and storage capacity can be effectively formed in the goaf. The present invention not only achieves a breakthrough at the technical level, but also demonstrates its far-reaching application potential at the economic and environmental levels, providing an innovative, efficient and environmentally friendly solution for the treatment of mine solid waste and the storage of CO2. By combining CO2 with mine waste, the disposal of waste is achieved, and the storage of CO2 is achieved, and the storage capacity is increased, which contributes to the "dual carbon target" and has significant environmental and social benefits. This method can not only effectively utilize mine waste and reduce environmental pollution, but also achieve long-term storage of carbon dioxide. It has the advantages of simple operation and environmental friendliness, and is suitable for large-scale industrial applications. It has wide practicability in the field of this technology.

[0018] The main advantages of the present invention compared with the prior art are:

[0019] 1) It has high practicality and wide application value, and provides an economically feasible solution for the resource utilization of mine solid waste and CO2 storage.

[0020] 2) It can achieve efficient storage of CO2 while ensuring that the mechanical properties of the filling body meet the needs of mining engineering.

[0021] 3) The filling materials used mainly include solid waste materials such as coal gangue, fly ash, and cement. Through innovative bonding technology, not only the resource disposal of solid waste is realized and the processing cost is reduced, but also significant economic and environmental benefits are brought to the mine. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 It is a schematic flow chart of the method for segmented solidification and sealing of CO2 by gangue-based cemented filling body of the present invention.

[0023] Figure 2 It is a three-dimensional schematic diagram of the method for segmented solidification and sealing of CO2 by gangue-based cemented filling body of the present invention.

[0024] In the figure: 1- coal gangue, 2- cement, 3- fly ash, 4- gas-liquid two-phase reaction monitoring and sealing device, 5- smoke capture device, 6- special transportation filling material conveying system, 7- filling working face, 8- gas injection pipeline. DETAILED DESCRIPTION

[0025] The embodiments of the present invention will be further described below in conjunction with the accompanying drawings:

[0026] The present invention provides a method for storing carbon dioxide by segmented solidification of a gangue-based cemented filling body, and the specific steps are as follows:

[0027] Step S1, raw material proportion: First, prepare the raw materials for the preparation of gangue-based cemented filling body, and mix gangue 1, cement 2, fly ash 3 and water according to the set mass percentage ratio; the set mass percentage is: gangue accounts for 45-55%, fly ash accounts for 15-25%, cement accounts for 5-15%, and water accounts for 15-25%. In the mixing process, the raw materials are added to the mixer in batches for mixing. During the mixing process, it should be ensured that all components are evenly dispersed to avoid uneven performance of the filling body due to inconsistent local concentrations. Add the raw materials to the mixer in batches for mixing, first add large particles, then add small particles, and finally add water to reduce the influence of large particles on the mixing uniformity; all components are evenly dispersed to avoid uneven performance of the filling body due to inconsistent local concentrations.

[0028] Step S2, slurry preparation: input the raw materials configured in step S1 into the gas-liquid two-phase reaction monitoring closed device 4, and perform deep stirring to form a gangue-based cementing filling material; in the process of mixing and stirring the configured raw materials, the consistency and fluidity of the slurry need to be closely monitored, and according to the actual situation on site, the proportion of gangue accounting for 45-55%, fly ash accounting for 15-25%, cement accounting for 5-15%, and water accounting for 15-25% is used to ensure that the consistency and fluidity of the slurry meet the filling process requirements of having both consistency and still being able to flow. Since the consistency of the slurry will gradually increase after the cement begins to hydrate during the stirring process, when the slurry reaches the "plastic" stage, that is, it has a certain consistency but is still able to flow, it meets the filling process requirements.

[0029] Step S3, CO2 blending: During the stirring process of step S2, the CO2 gas captured from the industrial flue gas is introduced into the gangue-based cementing filling material by the flue gas capture device 5 to continue stirring, to ensure that the CO2 and the gangue-based cementing filling material are fully mixed and reacted to form a uniformly dispersed gangue-based cementing filling slurry; before the CO2 gas captured from the industrial flue gas is introduced into the gangue-based cementing filling material, the throttle valve of the gas-liquid two-phase reaction monitoring closed device 4 is first adjusted to the minimum value, and then the CO2 gas tank is unscrewed to reduce the external pressure. Adjust to 0.5MPa. At this time, the CO2 gas has been decompressed by the pressure reducing valve. Turn on the motor to control the stirring speed to 50rad / s, and then slowly open the throttle valve. At this time, the flow meter starts to read. CO2 gas is introduced while stirring. When CO2 no longer reacts with the gangue-based cementitious filling body, CO2 is enriched in the pipeline and above the mixing tank until the pressure gauge value above the mixing tank is stable or the instantaneous flow reading of the flow meter is zero. At this time, it can be considered that the reaction between concrete and CO2 has ended, and the gangue-based cementitious filling body has been fully absorbed by CO2.

[0030] Step S4, filling body transportation: the gangue-based cementing filling body slurry prepared in step S3 is continuously transported from the preparation site to the filling working surface 7 through a pipeline or a special transport filling material conveying system 6; during the continuous transportation from the preparation site to the filling working surface 7, the flow state of the slurry is monitored by sensors and monitoring equipment installed in the conveying pipeline to prevent the slurry from precipitating, segregating or over-thickening. The slurry proportion is adjusted according to actual conditions. If the slurry does not flow smoothly in the pipeline or blockage occurs, the amount of water needs to be increased. If the slurry settles too quickly during transportation, or segregation occurs on the filling working surface 7, the amount of solid raw materials needs to be increased to ensure the fluidity and consistency of the slurry proportion and avoid excessive thickening, which affects the quality of the filling body and the final filling effect.

[0031] Step S5, backfill hardening and CO2 sealing: The gangue-based cemented backfill slurry undergoes a natural or accelerated hardening process at the filling working surface 7 to form a gangue-based cemented backfill with expected mechanical properties; after the backfill slurry in the filling working surface 7 is hardened, CO2 is injected into the gangue-based cemented backfill in the filling working surface 7 through the gas injection pipeline 8 to complete the final CO2 sealing process. After the backfill slurry in the filling working surface 7 is hardened, a large number of tiny pores are formed inside, and the cracks in the backfill further develop under the action of the overlying rock formation, CO2 is injected again at this time to complete the CO2 sealing.

Claims

1. A method for storing carbon dioxide by segmented solidification of gangue-based cemented filling, characterized in that: The following steps are involved: Step S1, raw material ratio: first, according to a set mass percentage, coal gangue (1), cement (2), fly ash (3) and water are mixed; Step S2, slurry preparation: input the raw materials prepared in step S1 into the gas-liquid two-phase reaction monitoring closed device (4), and perform deep stirring to form a gangue-based cemented filling material; Step S3, CO2 blending: During the stirring process of step S2, the CO2 gas captured from the industrial flue gas is introduced into the gangue-based cementitious filling material by using the flue gas capture device (5) and the stirring is continued to ensure that the CO2 and the gangue-based cementitious filling material are fully mixed and reacted to form a uniformly dispersed gangue-based cementitious filling slurry; Step S4, filling material transportation: the gangue-based cemented filling material slurry prepared in step S3 is continuously transported from the preparation site to the filling working surface (7) through a pipeline or a dedicated filling material transportation system (6); Step S5, backfill hardening and CO2 sealing: the gangue-based cemented backfill slurry undergoes a natural or accelerated hardening process at the filling working surface (7) to form a gangue-based cemented backfill with expected mechanical properties; after the backfill slurry in the filling working surface (7) is hardened, CO2 is injected into the gangue-based cemented backfill in the filling working surface (7) through the gas injection pipeline (8) to complete the final CO2 sealing process.

2. The method for storing carbon dioxide by segmented solidification of gangue-based cemented filling body according to claim 1, characterized in that: In step S1, the set mass percentages are: 45-55% for coal gangue, 15-25% for fly ash, 5-15% for cement, and 15-25% for water.

3. The method for storing carbon dioxide by segmented solidification of gangue-based cemented filling body according to claim 1, characterized in that: In step S1, during the mixing process, the raw materials are added to the mixer in batches for mixing, with large particles added first, small particles added second, and water added last, so as to reduce the influence of large particles on the mixing uniformity; all components are evenly dispersed to avoid uneven filling performance due to inconsistent local concentrations.

4. The method for storing carbon dioxide by segmented solidification of gangue-based cemented filling body according to claim 1, characterized in that: In step S2, during the mixing and stirring of the prepared raw materials to form the gangue-based cemented filling material, the consistency and fluidity of the slurry need to be closely monitored, and the proportion of the slurry is adjusted according to actual conditions to ensure that the consistency and fluidity of the slurry meet the filling process requirements.

5. The method for storing carbon dioxide by segmented solidification of gangue-based cemented filling body according to claim 1, characterized in that: In step S3, before the CO2 gas captured from the industrial exhaust gas is introduced into the gangue-based cementitious filling material for continued stirring, the throttle valve of the gas-liquid two-phase reaction monitoring and sealing device (4) is first adjusted to the minimum value, and then the CO2 gas tank is unscrewed to adjust the external pressure to 0.5MPa. At this time, the CO2 gas has been reduced in pressure by the pressure reducing valve. Then the motor is turned on to control the stirring speed to 50rad / s, and the throttle valve is slowly unscrewed. At this time, the flow meter starts to read, and CO2 gas is introduced while stirring. When CO2 no longer reacts with the gangue-based cementitious filling material, CO2 is enriched in the pipeline and above the mixing tank until the pressure gauge value above the mixing tank is stable or the instantaneous flow reading of the flow meter is zero. At this time, the reaction between concrete and CO2 is completed, and the gangue-based cementitious filling material has been fully absorbed by CO2.

6. The method for storing carbon dioxide by segmented solidification of gangue-based cemented filling body according to claim 1, characterized in that: In step S4, during the continuous transportation from the preparation site to the filling working surface (7), the flow state of the slurry is monitored by sensors and monitoring equipment installed in the transportation pipeline to prevent the slurry from settling, segregating or over-thickening. The slurry ratio is adjusted according to actual conditions. If the slurry does not flow smoothly in the pipeline or is blocked, the amount of water needs to be increased. If the slurry settles too quickly during transportation or segregates on the filling working surface (7), the amount of solid raw materials needs to be increased to ensure the fluidity and consistency of the slurry ratio and avoid over-thickening, which affects the quality of the filling body and the final filling effect.

7. The method for storing carbon dioxide by segmented solidification of gangue-based cemented filling body according to claim 1, characterized in that: In step S5, after the filling slurry in the filling working surface (7) is hardened, a large number of tiny pores are formed inside the gangue-based cemented filling body, and the cracks in the filling body are further developed under the action of the overlying rock layer, CO2 is injected again.

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