A coal-based solid waste negative carbon efficient filling mining method

Abstract

The present invention discloses a coal-based solid waste negative carbon efficient filling mining method, which specifically comprises the following steps: the coal gangue is crushed and transported to the filling area behind the working face; after a cycle of coal mining, a porous bottom-discharging scraper conveyor is used to drop the material from top to bottom; and a spraying device simultaneously sprays supercritical CO on the coal gangue in the falling process. 2 , making CO 2 The particles are distributed in the gaps between the gangue particles, and then the fast-setting materials are sprayed in time. The fast-setting materials expand and solidify in a very short time, and the CO2 in the gaps between the gangue and the particles is removed. 2 The negative carbon filling body is solidified to complete a filling cycle, and the cycle is repeated until the filling operation of the goaf is completed. The present invention is simple in design, safe and efficient, and combines filling mining and CO 2 The organic combination of sealing and storage provides a new negative carbon filling mining technology for promoting the comprehensive utilization of mine solid waste and advancing the construction of green mines, and it has broad application prospects.

Description

Technical Field

[0001] The present invention relates to the technical field of CO2 storage and filling mining, and in particular to a method for efficiently filling and mining coal-based solid waste with negative carbon. Background Art

[0002] At present, the technology of using solid waste from mines to fill the goaf and seal CO2 at the same time in mines mainly uses solid waste as raw materials to prepare filling materials, transport them to the goaf for filling after pretreatment, and then inject CO2 for sealing. However, the current technology has the disadvantages of small storage capacity and slow adsorption rate and the possibility of gas leakage, which limits the storage efficiency of CO2. In addition, the use of additives in the pretreatment process of filling materials and the increase in processing steps make the filling cost high. Therefore, how to simply and efficiently increase the storage capacity, storage speed and storage stability of CO2 is the key to current research. Summary of the invention

[0003] In view of the above-mentioned technical deficiencies, the purpose of the present invention is to provide a coal-based solid waste negative carbon efficient filling and mining method, which can solve the problems existing in traditional CO2 storage.

[0004] In order to solve the above technical problems, the present invention adopts the following technical solutions:

[0005] The present invention provides a coal-based solid waste negative carbon efficient filling mining method, comprising the following steps:

[0006] S1: A multi-hole bottom-discharging scraper conveyor and a spraying device are arranged on the coal mining support;

[0007] S2: Entering the initial state of the filling cycle, adjusting the grouting pressure and grouting volume according to the distance between the injection device and the porous bottom discharge scraper conveyor, and preparing the crushed coal gangue before mining, and transporting it to the area to be filled behind the working face;

[0008] S3: While the working face is being mined, the gangue is transported and dropped by a porous bottom-discharging scraper conveyor, and at the same time, the injection device sprays supercritical CO2 to distribute it in the pores of the gangue particles;

[0009] S4: After the supercritical CO2 fills the pores, stop dropping the material and spray the fast-setting material promptly. The fast-setting material gels, expands and solidifies quickly to seal the supercritical CO2 in the pores. The gangue consolidation structure and the liquid supercritical CO2 form a negative carbon filling body, thus completing a filling cycle.

[0010] S5: Repeat the filling in the order of steps S2 to S4 for multiple cycles. In this process, coal is cut, racks are moved and filling is performed at the same time until the entire goaf is filled according to the design requirements.

[0011] Preferably, a spraying device is selected which can realize high and low angle cyclic spraying in the vertical direction; when the spraying angle of the spraying device is low, the spraying range covers the coal gangue accumulated at the bottom, and when the spraying angle is high, the falling coal gangue is impacted to a higher position under the action of high-pressure spraying and becomes sticky, thereby realizing the connection of the negative carbon filling body to the top.

[0012] Preferably, the fast-setting material and liquid supercritical CO2 are stored separately and sprayed alternately through two independent pipelines corresponding to the injection device.

[0013] Preferably, after spraying, CO2 is rapidly distributed in the pores of the gangue accumulation, and the rapid adhesive material rapidly expands and consolidates between the gangue particles to form a large number of stable pores, sealing the liquid supercritical CO2 in the pores to form a CO2 storage body; the consolidated gangue and liquid supercritical CO2 form a negative carbon filling body as a whole.

[0014] Preferably, the falling gangue is squeezed due to the impact of shotcrete, and the rapidly solidified gangue exerts pressure on the liquid supercritical CO2, which can meet the pressure conditions for the storage of liquid supercritical CO2, that is, P>7Mpa; at the same time, the high temperature underground environment generated by the mine geothermal energy also meets the temperature conditions for the storage of liquid supercritical CO2, that is, T>31.5℃, so the liquid supercritical CO2 can be stably sealed in the negative carbon filling body without phase change.

[0015] Preferably, the rapid bonding material is a bonding material with high bonding strength, fast curing speed and large consolidation strength, that is, the setting time is less than 0.5h.

[0016] The beneficial effects of the present invention are as follows: the present invention uses grouting to directly pour the fast-setting material and supercritical CO2 onto the gangue for consolidation to form a CO2 storage body, which simplifies the compaction and pretreatment processes in the original technology and reduces the time cost and material cost. At the same time, the negative carbon filling body in this technology can achieve rapid cementation, so it is conducive to the storage of a large amount of supercritical CO2 in a relatively short time, and can achieve efficient CO2 storage while promoting the resource utilization of mine solid waste, and promote the reduction of greenhouse gas emissions in mines. This technology is safe, efficient and feasible. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0018] Figure 1A schematic diagram of spraying supercritical CO2 in the first cycle provided for this embodiment;

[0019] Figure 2 A schematic diagram of the first cycle of spraying the fast-setting material to form a filling body provided in this embodiment;

[0020] Figure 3 Schematic diagram of the second cycle spraying supercritical CO2 provided for this embodiment.

[0021] In the figure: 1-coal gangue; 2-coal mining machine; 3-negative carbon filling body; 4-coal mining support; 5-coal seam; 6-porous bottom discharge scraper conveyor; 7-injection device; 8-CO2 storage body; 9-solidified fast-setting material; 10-fast-setting material. DETAILED DESCRIPTION

[0022] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0023] A coal mine working face adopts a coal-based solid waste negative carbon high-efficiency filling mining method to achieve goaf filling and carbon sealing. A porous bottom discharge scraper conveyor 6 and an injection device 7 are arranged on the coal mining support 4, and a coal mining machine 2 is arranged next to the coal mining support 4; then the mining step is entered;

[0024] Step 1: Entering the initial state of a filling cycle, at this time, the grouting pressure and grouting amount are adjusted according to the distance between the injection device 7 and the porous bottom discharge scraper conveyor 6, and the crushed coal gangue 1 is prepared before the coal seam 5 is mined, and it is transported to the area to be filled behind the working face;

[0025] Step 2: While the working face is being mined, the coal gangue is transported and dropped by the porous bottom-discharging scraper conveyor 6 behind the coal mining support 4, and at the same time, the injection device 7 sprays liquid supercritical CO2 to distribute it in the pores between the coal gangue 1 particles; see Figure 1 ;

[0026] Step 3: After the supercritical CO2 fills the pores, stop dropping the material and spray the fast-setting material 10 immediately. The fast-setting material 10 can quickly gel, expand and solidify to form a solidified fast-setting material 9, which seals the liquid supercritical CO2 in the pores. The gangue consolidation structure and the liquid supercritical CO2 are pressurized together to form a negative carbon filling body 3. In this way, a filling cycle is completed; see Figure 2 ;

[0027] Step 4: Repeat the order of Steps 1 to 3 for multiple cycles of filling. In this process, coal is cut, racks are moved, and filling is performed until the entire goaf is filled according to the design requirements. Figure 3 .

[0028] The injection device 7 uses an existing device, such as the injection device disclosed in the patent application "A long-distance continuous injection device and injection control method in a coal mine" with publication number CN113605936A, which can realize angle-controlled injection in the vertical direction; when the injection angle of the injection device 7 is low, the spraying range covers the coal gangue 1 accumulated at the bottom, and when the injection angle is high, the falling coal gangue is impacted to a higher position under the action of high-pressure injection and becomes sticky, thereby realizing the connection of the negative carbon filling body 3 to the top.

[0029] The fast-setting material 10 and the liquid supercritical CO 2 are stored separately and sprayed alternately through two independent pipelines of the injection device 7 .

[0030] After spraying, CO2 is rapidly distributed in the pores of the gangue accumulation, and the rapid adhesive material 10 rapidly expands and consolidates between the gangue particles to form a large number of stable pores, sealing the liquid supercritical CO2 in the pores to form a CO2 storage body 8; the consolidated gangue and liquid supercritical CO2 form a negative carbon filling body 3 as a whole.

[0031] The rapid cementing material 10 used in this embodiment is an existing high-water quick-setting material, which is a new type of non-hydraulic silicate cementitious material. Its setting time is 28 minutes, and the final strength can reach 6.2 MPa. The final strength of the formed negative carbon filling body 3 can reach 3.6 MPa. The production capacity of the working face is 450,000 t / a, and it can achieve 153,000 to 216,000 tons of negative carbon.

[0032] Obviously, those skilled in the art can make various changes and modifications to the present invention without departing from the spirit and scope of the present invention. Thus, if these modifications and variations of the present invention fall within the scope of the claims of the present invention and their equivalents, the present invention is also intended to include these modifications and variations.

Claims

1. A coal-based solid waste negative carbon efficient filling mining method, characterized in that: The following steps are involved: S1: A multi-hole bottom-discharging scraper conveyor (6) and a spraying device (7) are arranged on the coal mining support (4); the spraying device (7) is selected to be able to realize high and low angle circulation spraying in the vertical direction; S2: Entering the initial state of the filling cycle, adjusting the grouting pressure and the grouting volume according to the distance between the injection device (7) and the porous bottom discharge scraper conveyor (6), and preparing the crushed coal gangue (1) before mining, and transporting it to the area to be filled behind the working face; S3: While the working face is being mined, the gangue (1) is transported and dropped by a porous bottom-discharging scraper conveyor (6), and at the same time, the injection device (7) sprays supercritical CO2 so that it is distributed in the pores of the gangue (1) particles; When the spraying angle of the injection device (7) is low, the spraying range covers the coal gangue (1) accumulated at the bottom, while when the spraying angle is high, the falling coal gangue is impacted to a higher position under the action of high-pressure spraying and becomes cohesive, thereby achieving the connection of the negative carbon filling body (3) to the top; S4: After the supercritical CO2 fills the pores, stop dropping the material and spray the fast-setting material (10) promptly and quickly. The fast-setting material should have high bonding strength, fast curing speed and high consolidation strength, i.e., the setting time is less than 0.5h. The fast-setting material (10) and the liquid supercritical CO2 are stored separately and sprayed alternately through two independent pipelines corresponding to the injection device (7); The fast-setting material (10) gels, expands, and solidifies quickly, sealing the supercritical CO2 in the pores. That is, the falling gangue is squeezed by the impact of the shotcrete, and the rapidly solidified gangue exerts pressure on the liquid supercritical CO2, which can meet the pressure conditions for the storage of liquid supercritical CO2, that is, P>7Mpa; at the same time, the underground high-temperature environment generated by the mine geothermal heat also meets the temperature conditions for the storage of liquid supercritical CO2, that is, T>31.5°C, so the liquid supercritical CO2 can be stably sealed in the negative carbon filling body (3) without phase change; the gangue consolidation structure and the liquid supercritical CO2 form a negative carbon filling body (3), completing a filling cycle; S5: Repeat the filling in the order of steps S2 to S4 for multiple cycles. In this process, coal is cut, racks are moved and filling is performed at the same time until the entire goaf is filled according to the design requirements.

2. A coal-based solid waste negative carbon efficient filling mining method as claimed in claim 1, characterized in that: After spraying, CO2 is rapidly distributed in the pores of the gangue accumulation, and the rapid adhesive material (10) rapidly expands and consolidates between the gangue particles to form a large number of stable pores, sealing the liquid supercritical CO2 in the pores to form a CO2 storage body (8); the consolidated gangue and the liquid supercritical CO2 form a negative carbon filling body (3) as a whole.

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