Bag type filling synergistic mineralization carbon dioxide sequestration method for exploiting red mud-based filling material based on aluminum strip under coal

Abstract

The invention belongs to the technical field of filling of an aluminum goaf under coal, and particularly relates to a bag type filling synergistic mineralization carbon dioxide sequestration method for mining a red mud-based filling material based on an aluminum strip under coal. Comprising the following steps that S1, filling bags are arranged; s2, grouting the aluminum layer bottom plate; s3, CO2 is conveyed; s4, red mud slurry is injected; s5, grouting between coal and aluminum layers; according to the method, through aluminum layer bottom plate grouting and coal aluminum interlayer grouting, Ordovician limestone water is effectively prevented from protruding out, harmful substances are effectively prevented from permeating underground water, meanwhile, a sealing cover layer for CO2 injection is also used, and the mineralization amount of CO2 is effectively increased. The main components of the red mud slurry are red mud, fly ash and crushed coal gangue, solid waste accumulation and environmental pollution are effectively reduced while the filling cost is remarkably reduced, recycling is achieved, the red mud is sealed in a flexible filling bag in a goaf, and if necessary, valuable elements in the red mud can be used for filling the goaf. And the tea leaves can also be extracted.

Description

Technical Field

[0001] The invention relates to the technical field of filling aluminum goafs under coal, and in particular to a method for co-mineralizing and storing carbon dioxide using bag-type filling of red mud-based filling materials based on aluminum strip mining under coal. Background Art

[0002] Red mud is a strong alkaline solid industrial waste produced in the process of producing alumina from bauxite. Its high pH value and specific chemical composition make red mud face certain challenges in environmental protection and resource utilization. Therefore, how to effectively treat and utilize red mud, reduce its impact on the environment, and realize the resource utilization of red mud has become the focus of current and future research.

[0003] Aluminum ore bodies under coal are usually located below coal seams. For upstream bauxite mining, after the overlying coal seams are mined, the original rock stress field changes dramatically, and the collapse of the roof of the coal seam goaf causes stress redistribution, inducing cracks in the roof of the bauxite layer to penetrate, forming water channels or risks of falling. Therefore, filling mining of aluminum under coal is the only way to ensure mine safety. Red mud is a kind of bulk solid waste, and solid waste filling mining method is one of the effective ways to deal with red mud. Using red mud as a filling material can not only reduce environmental pollution but also realize the secondary utilization of resources. Summary of the invention

[0004] The present invention is to solve the environmental hazards caused by the current large amount of red mud stacking, and how to solve the problem of mineralization and storage of carbon dioxide at the same time, and provides a method for coordinated mineralization and storage of carbon dioxide based on the mining of aluminum strips under coal with red mud-based filling materials. The grouting reinforced coal-aluminum interlayer grouting layer and the aluminum layer bottom plate grouting layer and the strip aluminum columns left by the mining of aluminum strips under coal form a multi-layer support structure, forming a carbon dioxide capping layer to increase the amount of carbon dioxide mineralization, and the support structure also provides a guarantee for the safe mining of bauxite under coal.

[0005] In order to solve the above technical problems, the technical solution adopted by the present invention is: a method for bag filling of red mud-based filling materials for synergistic mineralization and storage of carbon dioxide based on aluminum strip mining under coal, comprising the following steps: S1, arrangement of filling bags: after the aluminum layer under coal mining working face, the soft filling bags are arranged at intervals on the top plate of the aluminum layer goaf, and the filling bags are connected in sequence with hard material delivery pipes; S2, grouting of aluminum bottom plate: drilling grouting holes under the aluminum layer, pumping the grouting material into the grouting pipe I through the grouting pump at the ground grouting station, and then pushing the grouting material into the aluminum bottom plate through the grouting pipe I; S3, CO2 transportation: The gas pipeline transports CO2 from the CO2 pump station on the ground to the filling bag through the grouting pipeline II, and transports CO2 to the red mud slurry mixing station on the other hand; S4, injection of red mud slurry: after the red mud slurry is mixed and stirred in the red mud slurry mixing station on the ground, it is injected into the filling bag arranged in the aluminum layer goaf through the grouting pipeline II; S5, grouting between coal and aluminum layers: Drill grouting holes in the middle layer between the coal seam and the aluminum layer, and pump the grouting material into the grouting pipeline I through the grouting pump from the ground grouting station and inject it into the coal and aluminum layers.

[0006] As a further limitation of the technical solution of the present invention, in step S1, the mining of the aluminum layer under the coal is strip mining, the mining and retention ratio of the strip mining is 3:1, the mining rate is 75%, and the strip aluminum columns are not mined and retained as support; the flexible filling bag contains a waterproof film, which can isolate the flow of liquid and gas inside and outside; the filling bag is a rectangular shape of 10m*10m*5m, the interval between the filling bags is 10 meters, and the filling bags are connected with hard steel pipes, and the steel pipe specifications are cylindrical seamless steel pipes with a diameter of 150mm.

[0007] As a further limitation of the technical solution of the present invention, the aluminum layer described in step S2 is the aluminum layer below the coal seam; the aluminum layer bottom plate grouting horizontal layer is located 5 to 20 meters below the aluminum layer; the grouting material of the aluminum layer bottom plate grouting layer is ordinary silicate cement slurry, which is pumped from the ground to the grouting pipeline I through a grouting pump, and then filled into the aluminum layer bottom plate from the grouting hole. Grouting reinforcement of the aluminum layer bottom plate prevents the protrusion of Ordovician ash water and prevents harmful substances from infiltrating into groundwater.

[0008] As a further limitation of the technical solution of the present invention, in step S3, red mud slurry and CO2 gas are transported in the grouting pipeline II. Initially, CO2 gas is transported for 30 minutes to 60 minutes before the red mud slurry is transported. The transportation process of the red mud slurry is carried out in an environment filled with CO2 gas.

[0009] As a further limitation of the technical solution of the present invention, the red mud slurry described in step S4 is a mixed slurry of red mud, fly ash, desulfurized gypsum, cement, water, crushed coal gangue and injected CO2 after mixing and stirring, and the red mud slurry flows and is transported through the steel pipe between the filling bags; wherein the mass ratio of red mud, fly ash, desulfurized gypsum, cement, and crushed coal gangue is: 3.5~6: 5~6.5: 0.75~1: 1: 4~6, CO2 is continuously injected during the stirring process of the red mud slurry, and the slurry concentration is 75%~83%. The red mud slurry is prepared into a 50mm*100mm cylindrical sample according to the above ratio, the uniaxial compressive strength of 28d is 6~9MPa, the slump is 220mm, and the pH of the red mud slurry solution is 6.5~8.5.

[0010] As a further limitation of the technical solution of the present invention, the ordinary Portland cement slurry injected in steps S2 and S5 uses ordinary Portland cement with a strength grade of 42.5 and a water-cement ratio of 0.5-0.7; the grouting holes in steps S2 and S5 are both drilled with a 219mm drill bit, and a 133mm steel pipe is inserted as a mouth guard pipe. The outer wall of the mouth guard pipe is sealed and fixed with cement slurry, and the lower part is drilled with a 178mm drill bit until the bottom elevation of the hole, and then pressure grouting is performed with a 159mm flower pipe.

[0011] As a further limitation of the technical solution of the present invention, the coal-aluminum interlayer grouting layer described in step S5 is that the coal seam is in the upper layer and the aluminum layer is in the lower layer; the grouting between the coal and aluminum layers is transported by the grouting pipeline I with ordinary Portland cement slurry; the grouting curtain after grouting the coal-aluminum interlayer grouting layer and the mudstone layer on the aluminum layer also serve as the top layer for carbon dioxide sealing; the vertical distance between the horizontal position of the coal-aluminum interlayer grouting layer and the top plate of the aluminum layer is greater than 1.5 times the height of the fracture zone generated after the excavation of the aluminum layer.

[0012] As a further limitation of the technical solution of the present invention, the order of step S4 and step S5 can be interchanged.

[0013] As a further limitation of the technical solution of the present invention, the aluminum layer bottom plate grouting and the coal-aluminum layer inter-grouting in steps S2 and S5 are performed by multi-layer grouting to further improve the grouting effect and the sealing effect.

[0014] Compared with the prior art, the present invention has the following beneficial effects: 1. The present invention uses aluminum layer bottom plate grouting and coal aluminum layer grouting to effectively prevent the outburst of Ordovician ash water and the infiltration of harmful substances into groundwater, and at the same time serves as a capping layer for injecting CO2, effectively increasing the mineralization amount of CO2.

[0015] 2. The main components of the red mud slurry of the present invention are red mud, fly ash and crushed coal gangue, which can significantly reduce the filling cost while effectively reducing the accumulation of solid waste and the pollution to the environment, thereby realizing the recycling of resources.

[0016] 3. The present invention seals the red mud in a flexible filling bag in the goaf, and the valuable elements in the red mud can be mined and extracted if they are urgently needed in the future. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 It is a schematic diagram of the plan view of strip mining and filling of the aluminum layer of the present invention.

[0018] Figure 2 This is a cross-sectional view of the filling arrangement of the aluminum layer working face under coal according to the present invention.

[0019] Figure 3 It is a schematic diagram of the overall structure of the mining and filling arrangement of aluminum strips under coal according to the present invention.

[0020] The following are marked in the figure: 1-CO2 pumping station; 2-red mud slurry mixing station; 3-grouting station; 4-grouting pipeline I; 5-grouting pipeline II; 6-gas pipeline; 7-grouting hole; 8-ground; 9-coal seam; 10-coal-aluminum interlayer grouting layer; 11-aluminum layer bottom plate grouting layer; 12-mudstone layer; 13-aluminum layer; 14-filling bag; 15-strip aluminum column. DETAILED DESCRIPTION

[0021] The present invention is further described below in conjunction with specific embodiments.

[0022] like Figure 1-3 As shown, the present invention provides a method for co-mineralization and storage of carbon dioxide using bag-type filling of red mud-based filling materials based on aluminum strip mining under coal, and the specific process steps are as follows: S1: After the aluminum layer 13 under the coal is mined, the flexible filling bags 14 are arranged at intervals on the roof of the aluminum layer 13 goaf, and the filling bags 14 are connected in sequence with hard material delivery pipes; the filling bags 14 are rectangular in shape of 10m*10m*5m, and the interval between the filling bags 14 is 10 meters, and they are connected in sequence with hard steel pipes; the waterproof membrane is bonded to the inside of the flexible filling bags 14 to isolate the slurry liquid of the red mud slurry deposited in the flexible filling bags 14, the groundwater and the flow of the injected CO2; the strip mining has a mining and retention ratio of 3:1, and the mining rate is 75%, and the strip aluminum columns 15 are not retained for support; S2: Drill a grouting hole 7 below the aluminum layer 13, pump the grouting material into the grouting pipe Ⅰ4 through a grouting pump from the ground grouting station 3, and then push the grouting material into the aluminum layer bottom plate through the grouting pipe Ⅰ4; the aluminum layer bottom plate grouting layer 11 is 5 to 20 meters below the aluminum layer 13; the grouting material of the aluminum layer bottom plate grouting layer 11 is ordinary silicate cement slurry with a strength grade of 42.5 and a water-cement ratio of 0.6; it is pumped from the ground to the grouting pipe Ⅰ4 through a grouting pump, and then filled into the aluminum layer bottom plate grouting layer 11 from the grouting hole 7; S3: On the one hand, the gas pipeline 6 transports CO2 from the CO2 pump station 1 on the ground 8 to the filling bag 14 through the grouting pipeline II5, and on the other hand, transports CO2 to the red mud slurry mixing station 2; CO2 gas is first transported for 30min~60min before starting to transport red mud slurry, and the transportation process of red mud slurry is carried out in an environment filled with CO2 gas; the grouting pipeline I4 is used to transport ordinary silicate cement slurry, and the grouting pipeline II5 is used to transport red mud slurry and CO2 gas; S4: After the red mud slurry is mixed and stirred at the red mud slurry mixing station 2 on the ground 8, it is injected into the filling bag 14 arranged in the goaf of the aluminum layer 13 through the grouting pipe II5; the red mud slurry is a mixed slurry after red mud, fly ash, desulfurized gypsum, cement, water, crushed coal gangue and injected CO2 are mixed and stirred, and the ratio of the red mud slurry is red mud: fly ash: desulfurized gypsum: cement: crushed coal gangue = 4:6:0.75:1:4, CO2 is continuously injected during the stirring process of the red mud slurry, and the slurry concentration is 78%; the filling bag 14 is connected to the filling bag 14 with a hard seamless steel pipe, and the red mud slurry flows and is transported through the steel pipe pipeline between the filling bags 14; S5: Drill grouting holes 7 in the middle layer between the coal seam 9 and the aluminum layer 13, and pump the grouting material into the grouting pipe Ⅰ4 through the grouting pump at the ground grouting station 3, and inject it into the coal-aluminum interlayer grouting layer 10; the coal-aluminum interlayer grouting layer 10 is located at the upper layer of the coal seam 9 and the lower layer of the aluminum layer 13; the grouting curtain after grouting the coal-aluminum interlayer grouting layer 10 and the mudstone layer 12 on the upper part of the aluminum layer 13 also serve as the top sealing layer of carbon dioxide; the vertical distance between the horizontal position of the coal-aluminum interlayer grouting layer 10 and the top plate of the aluminum layer 13 is greater than 1.5 times the height of the fracture zone generated after the excavation of the aluminum layer 13.

[0023] The mineralization absorption of CO2 in the method of the present invention is divided into two aspects. On the one hand, CO2 participates in the carbon fixation reaction in the red mud slurry mixing station on the ground. The carbonate generated by CO2 entering the liquid reacts with the hydroxide in the red mud slurry to produce an acid-base neutralization reaction. On the other hand, CO2 is adsorbed in the grouting pipe II and the flexible filling bag and the injected red mud slurry to mineralize CO2. The present invention uses aluminum layer bottom plate grouting and coal aluminum layer grouting to effectively prevent the outburst of Ordovician ash water and the infiltration of harmful substances into groundwater, while also serving as a capping layer for the injected CO2, effectively increasing the mineralization amount of CO2.

[0024] The main components of the red mud slurry of the present invention are red mud, fly ash and crushed coal gangue, which significantly reduces the filling cost while effectively reducing the accumulation of solid waste and the pollution to the environment, thereby realizing the recycling of resources.

Claims

1. A method for storing carbon dioxide by bag filling with red mud-based filling materials based on the mining of aluminum strips under coal, characterized in that: The following steps are involved: S1, arrangement of filling bags: after the aluminum layer under coal mining working face, the soft filling bags are arranged at intervals on the top plate of the aluminum layer goaf, and the filling bags are connected in sequence with hard material delivery pipes; S2, grouting of aluminum bottom plate: drilling grouting holes under the aluminum layer, pumping the grouting material into the grouting pipe I through the grouting pump at the ground grouting station, and then pushing the grouting material into the aluminum bottom plate through the grouting pipe I; S3, CO2 transportation: The gas pipeline transports CO2 from the CO2 pump station on the ground to the filling bag through the grouting pipeline II, and transports CO2 to the red mud slurry mixing station on the other hand; S4, injection of red mud slurry: after the red mud slurry is mixed and stirred in the red mud slurry mixing station on the ground, it is injected into the filling bag arranged in the aluminum layer goaf through the grouting pipeline II; S5, grouting between coal and aluminum layers: Drill grouting holes in the middle layer between the coal seam and the aluminum layer, and pump the grouting material into the grouting pipeline I through the grouting pump from the ground grouting station and inject it into the coal and aluminum layers.

2. According to claim 1, a method for coal-based aluminum strip mining based on red mud-based filling materials bag filling synergistic mineralization and storage of carbon dioxide is characterized in that: In step S1, the mining of the aluminum layer under the coal is strip mining, the mining and retention ratio of the strip mining is 3:1, the mining rate is 75%, and the strip aluminum columns are not mined and are retained as support; the flexible filling bag contains a waterproof film; the filling bag is a rectangular shape of 10m*10m*5m, the spacing between the filling bags is 10 meters, and the filling bags are connected with hard steel pipes, and the steel pipe specifications are cylindrical seamless steel pipes with a diameter of 150mm.

3. According to claim 1, a method for coal-based aluminum strip mining based on red mud-based filling materials bag filling synergistic mineralization and storage of carbon dioxide is characterized in that: The aluminum layer described in step S2 is the aluminum layer below the coal seam; the horizontal layer of the aluminum layer bottom plate grouting is located 5 to 20 meters below the aluminum layer; the grouting material of the aluminum layer bottom plate grouting layer is ordinary silicate cement slurry, which is pumped from the ground to the grouting pipe I through a grouting pump, and then filled into the aluminum layer bottom plate from the grouting hole.

4. According to claim 1, a method for coal-based aluminum strip mining based on red mud-based filling materials bag filling synergistic mineralization and storage of carbon dioxide is characterized in that: In step S3, red mud slurry and CO2 gas are transported in the grouting pipeline II. Initially, CO2 gas is transported for 30 minutes to 60 minutes before the red mud slurry is transported. The transportation process of the red mud slurry is carried out in an environment filled with CO2 gas.

5. According to claim 1, a method for coal-based aluminum strip mining based on red mud-based filling materials bag filling synergistic mineralization and storage of carbon dioxide is characterized in that: The red mud slurry described in step S4 is a mixed slurry obtained by mixing and stirring red mud, fly ash, desulfurized gypsum, cement, water, crushed coal gangue fragments and injected CO2; wherein the mass ratio of red mud, fly ash, desulfurized gypsum, cement and crushed coal gangue is: 3.5~6:5~6.5:0.75~1:1:4~6, CO2 is continuously injected during the stirring process of the red mud slurry, and the slurry concentration is 75%~83%.

6. The method of storing carbon dioxide by bag filling with red mud-based filling materials based on aluminum strip mining under coal according to claim 1 is characterized in that: The ordinary Portland cement slurry injected in steps S2 and S5 uses ordinary Portland cement with a strength grade of 42.5 and a water-cement ratio of 0.5-0.7; the grouting holes in steps S2 and S5 are both drilled with a 219mm drill bit, and a 133mm steel pipe is inserted as a mouth guard pipe. The outer wall of the mouth guard pipe is sealed and fixed with cement slurry, and the lower part is drilled with a 178mm drill bit until the bottom elevation of the hole, and then a 159mm flower pipe is used for pressure grouting.

7. The method of claim 1 for synergistic mineralization and storage of carbon dioxide using bag-type filling of red mud-based filling materials based on aluminum strip mining under coal, characterized in that: The coal-aluminum interlayer grouting layer described in step S5 is that the coal layer is at the upper layer and the aluminum layer is at the lower layer; the grouting pipeline I transports ordinary silicate cement slurry for grouting the coal-aluminum interlayer; the grouting curtain after grouting the coal-aluminum interlayer grouting layer and the mudstone layer above the aluminum layer also serve as the top layer of carbon dioxide sealing; The vertical distance between the horizontal position of the grouting layer between the coal and aluminum layers and the top plate of the aluminum layer is greater than 1.5 times the height of the fracture zone generated after the aluminum layer is excavated.

8. The method for storing carbon dioxide by bag filling with red mud-based filling materials based on aluminum strip mining under coal according to claim 1 is characterized in that: The order of step S4 and step S5 can be interchanged.

9. The method of claim 1 for storing carbon dioxide by bag filling with red mud-based filling materials based on aluminum strip mining under coal, characterized in that: In steps S2 and S5, the aluminum layer bottom plate grouting and the coal-aluminum layer interlayer grouting are performed by multi-layer grouting.

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