CN114961845B - A method for carbon sequestration in gobs based on layered tailings cemented filling mining - Google Patents

Abstract

The invention relates to a goaf carbon sequestration method based on stratified approach tailing cemented filling mining, and belongs to the field of carbon dioxide sequestration of metal mines. Mining the side wall of the current layered ore body according to a return-font approach, and sealing the side walls except the connecting roadway by using an airtight material; mining internal ore bodies by a layering approach filling method, filling reserved empty areas at intervals by using a tailing cemented filling body by a downward layering method, and filling the reserved empty areas at intervals by using the tailing cemented filling body and waste rocks by an upward layering method; when the current layering operation is finished, erecting CO from a dead zone or a waste rock filling zone to a sectional transportation roadway in a connecting roadway ₂ The pipeline is used for sealing the communication lane by using an airtight material; when the current middle section operation is finished, the trapped CO is ₂ The CO is injected into a dead zone or a waste rock filling zone through a pipeline arranged along the return air path and increases along with the mining depth and the ground temperature ₂ And sealing in gas state to supercritical state for long time. The method is simple to operate and low in cost, and has important significance for sustainable utilization of underground space of the mine and green mining.

Description

A method for carbon sequestration in gobs based on layered tailings cemented filling mining

technical field

The invention relates to a goaf carbon sequestration method based on layered tailings cemented filling mining, which belongs to the field of carbon dioxide sequestration in metal mines.

Background technique

At present, the main sites for geological utilization and storage of carbon dioxide are deep saline water formations and oil and gas fields; among them, oil and gas fields mainly carry out oil flooding/gas recovery, and the storage volume is small; deep saline water formations have great storage potential, but the effective CO ₂ storage space Also only 2-3%, and well construction costs a lot. By 2050, _CO2 storage capacity will need to increase from about 40 million metric tons/year to more than 5.6 billion metric tons/year, relying on conventional geological resources such as deep saline aquifers, oil and gas fields, and may require nearly $1.3 trillion in capital investment. This poses challenges and creates new opportunities for finding low-cost, large-scale _CO2 storage sites.

By the end of 2015, China's metal and non-metal (non-coal) underground mines had a total of 1.28 billion m ³ of gobs, and the underground space resources of abandoned coal mines in 2020 were about 7.2 billion m ³ . Making full use of mine goaf resources to serve for CO ₂ underground storage is expected to greatly improve CO ₂ storage capacity and reduce storage costs. Because coal seams have a certain adsorption capacity for CO ₂ , and CO ₂ has the effect of displacing and increasing coalbed methane, carbon sequestration in goafs has been extensively studied in the field of coal mining, such as storing carbon dioxide in goafs filled with porous media Gas method, publication number CN110344877A), a method for _sequestering CO in abandoned coal mine goafs, publication number CN109812293A, a method for non-isolated coal pillar filling mining and construction of goaf storage, publication number CN114412464A, Mineralization utilizes CO ₂ waste gas ecological protection coal mining method, public number CN113622993A; however, the CO ₂ content that can be stored by coal seam adsorption is small, and the surrounding rock of the coal mine is relatively broken, and a large number of goafs collapse after mining, and the gobs are blocked Difficulty, easy to cause _CO2 leakage. The surrounding rock stability of metal mines is generally higher than that of coal mines, and the tailings cemented filling mining method has the functions of goaf control, ground pressure control, surface subsidence control, and tailings disposal, and has been widely used in metal mines. This has created good conditions for the partial filling of gobs in underground metal mines for carbon sequestration.

Tailings cemented filling body is a kind of slurry with a certain fluidity mixed with water, cement, tailings and additives, which is transported to the goaf, and after a period of hydration reaction, it is consolidated into an artificial medium with a certain strength body. The main components of the filling body are hydration products and tailings minerals. In the absence of groundwater erosion, CO ₂ reacts with hydration products as shown in Formula 1, and CO ₂ reacts with basic tailings minerals as shown in Formula 2. The reaction can generate high-strength CaCO ₃ and silica gel SiO ₂ ·nH ₂ O with gelling effect, thereby reducing the porosity of the filling body, improving the overall strength of the filling body, and gradually enhancing the sealing performance of the filling body.

(Ca,Mg) _x Si _y O _x+2y+z H _2z (s)+xCO ₂ (g)→x(Ca,Mg)CO ₃ (s)+ySiO ₂ zH ₂ O(am)

A tailings carbonization cemented filling method (authorized announcement number CN113213829B) utilizes the reaction mechanism between _CO2 and the filling body, and proposes a method of embedding a pipeline in the filling body to feed _CO2 into the filling body for mineralization and maintenance, but this method does not provide CO ₂ For the storage space, the amount of CO ₂ that can be stored in a short period of time by simply relying on mineralized carbon fixation is small, and the emission reduction efficiency is low.

In addition, a method for storing carbon dioxide gas in goafs filled with porous media (authorized announcement number CN110344877B), a method for sequestering _CO2 in goafs of abandoned coal mines (publication number CN109812293A unauthorized), a coal pillar-free A series of patents such as the method for backfill mining and construction of goaf storage (publication number CN114412464A unauthorized) and ecological protection coal mining method for mineralization and utilization of _CO2 waste gas (publication number CN113622993A unauthorized), although they all propose to reserve However, they are all aimed at thin horizontal (or gently inclined) ore bodies such as coal mines. Metal deposits are generally steeply inclined and extend greatly in the depth direction. The mining methods are quite different from coal mining. Moreover, the method for storing carbon dioxide gas in gobs filled with porous media (authorized notification number CN110344877B) adopts the technological process of pouring porous media filling bodies and then masonry filling strips using molds, which cannot be realized through the current filling system. Therefore, the above invention is not suitable for carbon sequestration in goafs of metal mines.

Contents of the invention

In view of the deficiencies of the above existing technologies, a safe and low-cost carbon sequestration method of tailings cemented filling gobs is provided, which combines carbon emission reduction and goaf filling treatment, and uses tailings cemented filling bodies to partially fill gobs Build long-term _CO2 storage sites in underground metal mines, and use _CO2 to react with tailings cemented filling bodies to permanently fix _CO2 in the filling body, reduce atmospheric carbon emissions, increase the strength of the filling body, and maintain the stability of the underground space sex. In addition, the present invention is combined with the layered approach filling mining method commonly used in metal ore mining, without changing the original filling system of the mine, which is easy to implement and requires little extra cost.

In order to achieve the above-mentioned technical purpose, a goaf carbon sequestration method based on layered tailings cemented filling mining of the present invention, the steps are as follows:

On the basis of layered tailings cemented filling mining, airtight materials are used to build a sealing layer at the ore body boundary of the metal mine to seal the entire goaf, and high-strength tailings are used to cement the filling body, artificial false roof or artificial false roof. The tailing sand cemented filling bodies filled at intervals in the bottom and goaf support the overall frame of the goaf, and reserve CO ₂ storage goafs or high-porosity CO ₂ storage waste rock filling areas in the goaf according to field conditions, carbon sequestration In the initial stage, the pipeline is used to fill the CO ₂ storage goaf or the CO ₂ storage waste rock filling area, and the _{CO 2 is} sealed in the goaf by relying on the airtight material on the boundary of the ore body. With the CO ₂ stored in the goaf Diffuse into the tailings cemented backfill, react with the basic tailings and cement hydration products in the tailings cemented backfill, consume CO ₂ and generate high-strength calcium carbonate CaCO ₃ and silica gel SiO ₂ with gelling effect. nH ₂ O, so as to improve the overall strength and air tightness of the tailings cemented filling body, reduce the porosity of the tailings cemented filling body, and achieve large, long-term and safe carbon sequestration;

Specific steps are as follows:

Step 1. Mining the side walls of the current layered ore body in a zigzag shape, using airtight materials to seal the side walls except the connecting roadway, leaving the stope connecting roadway and the layered connecting roadway to serve the currently mined layers;

Step 2. Use layered approach filling method to mine the internal ore body except the side wall. If the ore body is mined with the downward layered approach filling mining method, use the tailing sand cemented filling body to fill the goaf at intervals. Reserve the empty area for _CO2 storage. If the upward layered approach filling mining method is adopted, the approach of filling the goaf with cemented tailings and waste rock at intervals will form a _CO2 storage waste rock filling area;

_Step 3. After the current layering operation is completed, set up the _CO2 pipeline from the CO2 storage empty area or the _CO2 sequestration waste rock filling area to the section transportation roadway in the stope connection roadway and the layered connection roadway, and then use airtight materials Closed stope tie lanes and layered tie lanes;

Step 4. Repeat steps 1–3 layer by layer according to the layer-by-layer mining sequence until the current mid-stage operation is completed, and the captured CO ₂ is injected into the CO ₂ storage empty area or the CO ₂ storage waste through the CO ₂ pipeline arranged along the return air path. At the same time, the mining operation is transferred to the next middle section. With the increase of mining depth and ground temperature, _CO2 is stored in a gaseous state to a supercritical state for a long time.

Furthermore, during the mining process, the division of the middle section of the ore body, subsections, and layers, as well as the mining and filling sequence along the depth direction of the ore body are completely consistent with the layered approach filling mining method; each layered approach is divided into surrounding rocks and the sidewall approach on the boundary of the orebody and the orebody internal approach, the operation mode of each layered approach is to mine and close the sidewalls in the order of back and forth, and follow the approach from the two sides of the ore body to the middle of the ore body The principle of gradual advancement is to mine and fill the internal route. If there is a route that needs to reserve a CO ₂ storage space or a high-porosity CO ₂ storage waste rock filling area, skip this route first, and continue mining and filling. One route, when both sides of the route need to be reserved for CO ₂ storage vacancy or high-porosity CO ₂ storage waste rock filling area are filled, then the route is mined, and then left empty or filled with waste rock Form CO ₂ storage empty area or high porosity CO ₂ storage waste rock filling area.

Further, the method of using airtight materials to seal the side walls except the connecting roadway is as follows: the outer side of the side road near the surrounding rock is filled with high-strength tailings cemented filling body, and the inner side of the side road near the ore body is filled with gas Fill with dense material, and reserve 1/10 of the width of the side road between the air-tight material and the unmined ore block inside as the isolation space for the impact of avalanche, to protect the filling body and sealing material of the two sides; use air-tight material to seal the side-side contact The method of roadway is as follows: the inner side of the layered roadway near the ore body is filled with airtight material, the outer side of the layered roadway near the surrounding rock is filled with high-strength tailing sand cemented filling body, and the stope roadway is all filled with tailings. Sand cemented filling body filling.

Furthermore, airtight artificial false roofs and airtight artificial false bottoms need to be set up for the top layer and bottom layer of the ore body respectively. When mining with the downward layering approach filling method, it is necessary to set up airtight artificial bottoms at the top of each middle section. If you choose to use the upward layered approach filling method for mining, you need to set up an airtight artificial false bottom at the bottom of each middle section. Through the airtight artificial false roof and airtight artificial false bottom, combined with the side The airtight material and high-strength tailings cement the filling body to form a stable carbon sequestration unit structure with the middle section as the unit.

Furthermore, the captured CO ₂ comes from mining enterprises’ dressing and smelting plants _, or the four major emission sources of electricity, cement, steel, and chemical _industry ; Air wells and air return lanes are connected to the CO ₂ pipeline at the intersection of the sectional transportation lane and the stope connecting lane, and CO ₂ is injected into the empty area or waste rock filling area to avoid CO ₂ pipeline leakage from polluting the fresh air flow.

Furthermore, the CO ₂ delivery pressure of the CO ₂ pipeline is controlled to maintain the stability of the side airtight material and the high-strength tailings cemented filling body, and at the same time partially tear the CO ₂ storage empty area or the tailings cemented filling around the CO ₂ storage waste rock filling area. The level of the gaseous _CO2 can be as low as below 1MPa, which is suitable for the goaf in the early stage of mining, where the buried depth of the ore body is less than 100m, and the ground stress and surrounding rock strength are low. As the intensity increases, the CO ₂ pressure charged can be gradually increased. When the ground temperature of the goaf is greater than 31°C and the mining depth is greater than 800m, it is considered to store CO ₂ in a supercritical state.

Further, _CO2 pressure sensors, airtight valves and flange interfaces are installed on the _CO2 pipeline near the intersection of stope roadway and section transportation roadway; when _CO2 injection is completed, close the airtight valve and loosen the flange interface, and then use the flange sealing interface to block the pipeline connected with the _CO2 storage area or the _CO2 storage waste rock filling area, and recycle the _CO2 pipeline on the current segmental transportation lane for reuse in the next segmental transportation lane. The rest of the CO ₂ pipeline from the surface CO ₂ pumping station to the current section remains unchanged, and extends down to the next section; the CO ₂ pressure sensor monitors the CO ₂ storage empty area or the CO ₂ storage waste rock filling area during storage. _CO2 pressure change.

Furthermore, _a CO ₂ concentration sensor is installed at intervals _of a section height in the surrounding rock near the side of the ore body for early warning of CO ₂ leakage; ₂ The reading of the _CO2 pressure sensor in the sealed waste rock filling area drops slowly, indicating that _CO2 has a mineralization reaction with the filling body. When the _CO2 pressure drops to 75% of the set pressure, the airtight valve and flange interface can be used to Reconnect the CO ₂ gas source to add pressure for the CO ₂ storage empty area or the CO ₂ storage waste rock filling area.

Further, the tailings cemented filling slurry used in the tailings cemented filling body includes mine tailings, Portland cement or fly ash mixed, steel slag composite Portland cement, water, additives, the concentration of the filling slurry is greater than 70%, 3d The strength is greater than 1MPa; the mass ratio of lime and sand in the tailings cemented filling body used in the downward layered filling method is greater than 1:6, and the 28d strength is greater than 3.5MPa; the mass of lime sand in the tailings cemented filling body used in the upward layered filling method The ratio is greater than 1:8, and the 28d strength is greater than 2MPa; the lime-sand mass ratio in the high-strength tailings cemented filling body on the side of the filling side road and the layered connection roadway is greater than 1:4, and the 28d strength is greater than 5MPa.

Further, the airtight material includes airtight concrete, asphalt-based airtight filling, and mine filling sealing material; the airtight artificial false roof and airtight artificial bottom include airtight concrete, concrete plus asphalt-based Composite structure of airtight filling material, composite structure of filling and sealing material for concrete plus ore.

Beneficial effect:

The present invention has the following technical advantages: 1) using tailings cemented filling body to partially fill gobs in underground metal mines to construct _CO2 storage sites to achieve efficient, large-scale, long-term physical storage of _CO2 ; 2) utilizing _CO2 and tailings The reaction of cemented filling body fixes CO ₂ in the filling body to achieve permanent and stable chemical storage of CO ₂ ; 3) utilizes the reaction of CO ₂ and tailings cemented filling body to gradually reduce the porosity of the filling body and increase the strength of the filling body to ensure the underground Spatial stability and closedness of the storage structure; 4) Combining with the layered approach filling mining method commonly used in metal ore mining, there is no need to change the original filling system of the mine, which is easy to implement and has low additional costs.

Description of drawings

Figure 1(a) is a schematic plan view of carbon sequestration along the ore body strike in the goaf of downward layered filling mining;

Figure 1(b) is a schematic diagram of a section along the thickness of the orebody for carbon sequestration in the goaf of down-layered filling mining;

Fig. 2 (a) is a schematic diagram of the carbon sequestration mining and filling sequence of the goaf carbon sequestration method based on the method of layered approach tailings cemented filling mining in the D1-D1 section area of Fig. 1 (b) according to the present invention;

Fig. 2 (b) is a schematic diagram of the carbon sequestration mining and filling sequence of the goaf carbon sequestration method based on the layered approach tailings cemented filling mining in the E1-E1 section area of Fig. 1 (b) according to the present invention;

Figure 3(a) is a schematic plan view of carbon sequestration along the ore body strike in the upward layered filling mining goaf;

Figure 3(b) is a schematic diagram of a section along the thickness of the ore body for carbon sequestration in the goaf of upward layered filling mining;

Fig. 4 (a) is a schematic diagram of the carbon sequestration mining and filling sequence of the goaf carbon sequestration method based on the layered approach tailings cemented filling mining in the D2-D2 section area of Fig. 3 (b) according to the present invention;

Fig. 4(b) is a schematic diagram of the carbon sequestration mining and filling sequence of the goaf carbon sequestration method based on the method of layered approach tailings cemented filling mining in the E2-E2 section area of Fig. 3(b) according to the present invention;

In the figure: 1. Airtight material; 2. CO ₂ storage space; 3. CO ₂ storage waste rock filling area; 4. Tailings cemented filling body; 5. High-strength tailings cemented filling body; 6. Air tightness Artificial false roof; 7. Airtight artificial false bottom; 8. Segmented transportation lane; 9. _CO2 pipeline; 10. Stope connecting lane; 11. Layered connecting lane;

Detailed ways

In order to illustrate the technical means and methods adopted in the present invention more clearly, the embodiments of the present invention will be further described below in conjunction with the accompanying drawings.

A goaf carbon sequestration method based on layered tailings cemented filling mining of the present invention, on the basis of layered tailings cemented filling mining, the airtight material 1 is used to construct the boundary of the ore body 12 of the metal ore The sealing layer seals the entire goaf, and the overall frame of the goaf is supported by the high-strength tailing sand cemented filling body 5 on the sides, the artificial false roof 6 or artificial false bottom 7, and the tailing sand cemented filling body 4 filled at intervals in the goaf. Reserve a _CO2 storage goaf 2 or a high-porosity _CO2 storage waste rock filling area 3 in the goaf according to field conditions, and use pipelines to _CO2 storage goaf 2 or _CO2 storage waste rock filling area 3 at the initial stage of carbon sequestration Fill CO ₂ , rely on the airtight material 1 on the boundary of the ore body 12 to seal the CO ₂ in the goaf, and diffuse the CO ₂ stored in the goaf into the cemented tailings filling body 4, and cement the filling body with the tailings sand The basic tailings in 4 react with cement hydration products, consume CO ₂ and generate high-strength calcium carbonate CaCO ₃ and silica gel SiO ₂ ·nH ₂ O with gelling effect, thereby improving the tailings cemented filling body 4 as a whole Strength and air tightness, reduce the porosity of the tailings cemented filling body, and achieve large, long-term and safe carbon sequestration;

Embodiment one

A goaf carbon sequestration method based on layered tailings cemented filling mining, when combined with the downward layered filling mining method, the specific steps and parameters are as follows:

The ore blocks are divided as shown in Figure 1(a) and Figure 1(b). The access road is 4m wide and the layer height is 3m. Each segment has three layers with a height of 9m, and each middle segment has three segments with a height of 27m. The tailing sand cemented filling body has a lime-sand ratio of 1:6, a filling slurry concentration of 75%, and a filling body with a strength of 1.5MPa at 3d and 3.5MPa at 28d. The high-strength tailings cemented filling body has a lime-sand ratio of 1:4, a filling slurry concentration of 75%, and a filling body with a strength of 2.5MPa at 3d and 5MPa at 28d. Airtight artificial roof 6 is built with airtight concrete at the top of each middle section. In addition, airtight artificial roof 6 and airtight artificial roof are respectively constructed with airtight concrete on the inner side of the ore body top layer and bottom layer near the ore body. The bottom 7 and the sides also adopt airtight concrete as the airtight filler 1.

As shown in Figure 2(a) and Figure 2(b), step 1. First excavate the stope tie roadway 10, and excavate layered tie wayway, two-side approach road and parallel layered roadway along the side of the stope in a zigzag shape. The side road of the connecting roadway is then filled in sequence with the side road and two side roads parallel to the layered connecting roadway, and the stope connecting roadway and the layered connecting roadway are used to serve the current stratification. C0-C11 in the figure are mining mining sequence; F0-F11 is the stope filling sequence, and the construction sequence is C0→C1→C2→C3→F0→F1. The inner side is filled with airtight concrete 1;

Step 2. Mining and filling the internal ore body with the downward layered approach method, filling the void area 2 with tailings cemented filling body 4 intervals, and the sequence of layered mining and filling of D1-D1 type is: C4→F2→C5→ F3→C6→C7→F4→C8→F5→C9→F6→C10→C11→F7, see Figure 2(a) for details; the sequence of layered mining and filling for E1–E1 is: C4→F2→C5→F3→ C6→F4→C7→F5→C8→C9→F6→C10→F7→C11, see Figure 2(b) for details;

Step 3. At the end of the current layering operation, erect the _CO2 pipeline 9 from the goaf 2 to the segmented transportation roadway 8 in the connecting roadway, firstly fill the inner side of the layered connecting roadway with airtight concrete 1, and then cement it with high-strength tailings The filling body 5 fills the outer side of the layered roadway and the stope roadway 10, that is, the filling sequence is F8→F9, see Figure 2 for details;

Step 4. At the end of the current mid-section operation, the _CO captured by the mine dressing and smelting plant is injected into the goaf through the pipeline 9 along the mine return air path through the return air shaft, the return air lane, the segmented transportation lane 8, and the stope connection lane 10 2. The CO ₂ pressure in the void area at the mining depth -100m level is 1MPa, and the CO ₂ pressure increases by 0.5MPa for every 50m decrease in the mining depth by about two mid-section heights.

Embodiment two

A goaf carbon sequestration method based on layered tailings cemented filling mining, when combined with the upward layered filling mining method, the specific steps and parameters are as follows:

The ore block division is shown in Figure 3(a) and Figure 3(b). The approach width is 4m, the layer height is 3m, each segment has three layers with a height of 9m, and each middle segment has three segments with a height of 27m. The tailing sand cemented filling body has a lime-sand ratio of 1:8, a filling slurry concentration of 75%, and a filling body with a strength of 1.2MPa at 3d and 2MPa at 28d. The high-strength tailings cemented filling body has a lime-sand ratio of 1:4, a filling slurry concentration of 75%, and a filling body with a strength of 2.5MPa at 3d and 5MPa at 28d. The waste rock filling rate in the waste rock filling area is 40%–50%, that is, 50%–60% of the space in the waste rock filling area is reserved for carbon sequestration. Airtight concrete is used to construct the airtight artificial false bottom 7 at the bottom of each middle section. In addition, airtight artificial roof 6 and airtight artificial roof 6 and airtight artificial roof are respectively constructed with airtight concrete for the inner lining of the ore body top layer and bottom layer near the ore body. The permanent artificial false bottom 7, the side also adopts airtight concrete as the airtight filling material 1.

As shown in Fig. 4(a) and Fig. 4(b), step 1. First excavate the stope connecting roadway 10, excavate layered connecting roadway, two-side approach road and parallel to layered The side road of the connecting roadway is then filled in sequence with the side road and two side roads parallel to the layered connecting roadway, and the stope connecting roadway and the layered connecting roadway are used to serve the current stratification. C0-C11 in the figure are mining mining sequence; F0-F11 is the stope filling sequence, and the construction sequence is C0→C1→C2→C3→F0→F1. The inner side is filled with airtight concrete 1;

Step 2. Mining and filling the internal ore body with the upward layered approach method, using tailings cemented filling body 4 and waste rock for interval filling, D2-D2 type layered and E2-E2 type layered approach for stope mining and The filling sequence is C4→F2→C5→F3→C6→F4→C7→F5→C8→F6→C9→F7→C10→F8→C11→F9, see Figure 4(a) and Figure 4(b) for details;

Step 3. At the end of the current layering _operation , set up the CO pipeline 9 from the waste rock filling area 3 to the segmental transportation roadway 8 in the connecting roadway, first fill the inner side of the layered connecting roadway with airtight concrete 1, and then use high-strength tailings The cemented filling body 5 fills the outer side of the layered roadway and the stope roadway 10, that is, the filling sequence is F10→F11, see Figure 4(a) and Figure 4(b) for details;

Step 4. At the end of the current mid-section operation, the _CO captured by the mine dressing and smelting plant is injected into waste rock filling through the pipeline 9 along the mine return air path through the return air shaft, return air lane, segmented transportation lane 8, and stope connecting lane 10 In zone 3, the CO ₂ pressure in the void area at the mining depth -100m level is 1MPa, and the CO ₂ pressure increases by 0.5MPa every time the mining depth decreases by 50m for about two mid-section heights.

Claims (10)

1. A goaf carbon sequestration method based on layered tailings cemented filling mining, characterized in that: on the basis of layered tailings cemented filling mining, the airtight material (1) is used in the metal ore A sealing layer is constructed at the boundary of the ore body (12) to seal the entire goaf, and the filling body (5), airtight artificial false roof (6) or airtight artificial bottom (7) and mining The tailing sand cemented filling body (4) that is filled at intervals in the goaf supports the overall framework of the goaf, and the CO ₂ storage goaf (2) or the high-porosity CO ₂ storage waste rock filling area is reserved in the goaf according to the actual situation (3) At the initial stage of carbon sequestration, the pipeline is used to fill CO ₂ into the CO ₂ sequestration empty area (2) or the CO ₂ sequestration waste rock filling area (3), relying on the airtight material (1) on the boundary of the ore body (12) to CO ₂ is sealed in the goaf, and with the CO ₂ stored in the goaf diffuses into the tailings cemented backfill (4), it reacts with the basic tailings and cement hydration products in the tailings backfill (4) , while consuming CO ₂ , high-strength calcium carbonate CaCO ₃ and silica gel SiO ₂ ‧nH ₂ O with gelling effect are generated, thereby improving the overall strength and airtightness of the tailings cemented filling body (4), and reducing the tailings cemented filling body (4) Porosity, to achieve large, long-term and safe carbon sequestration; Specific steps are as follows: Step 1. Mining the sides of the current layered ore body in a zigzag shape, using airtight materials (1) to seal the side walls except the connecting roadway, leaving the stope connecting roadway (10) and the layered connecting roadway (11) to serve the current mining layering; Step 2. Mining the internal ore body (12) except for the side wall with the layered approach filling method, if the ore body (12) is mined with the downward layered approach filling mining method, use tailings to cement the filling body (4) For the approach of filling the goaf at intervals, the CO ₂ storage vacancy (2) is reserved. If the upward layered approach is used for filling the mining method, the tailing sand cemented filling body (4) and waste rock are used to fill the goaf at intervals. The route forms a waste rock filling area for _CO2 storage (3); Step 3. After the current layering operation is completed, erect the CO ₂ storage empty area (2) or the CO ₂ storage waste rock filling area (3) to the section The _CO2 pipeline (9) of the transport lane (8), and then use the airtight material (1) to close the stope tie lane (10) and the layered tie lane (11); Step 4. Repeat steps 1–3 layer by layer according to the layer-by-layer mining sequence until the current mid-stage operation is completed, and the captured CO ₂ is injected into the CO ₂ storage space (2) or CO 2 through the CO ₂ pipeline arranged along the return air path. ₂ Seal up the waste rock filling area (3), and at the same time, the mining operation is transferred to the next middle section. With the increase of mining depth and ground temperature, CO ₂ is stored in a gaseous state to a supercritical state for a long time. 2. A goaf carbon sequestration method based on layered tailings cemented filling mining according to claim 1, characterized in that: during the mining process, the ore body (12) in the middle, segmented, layered The division, as well as the mining and filling sequence along the depth direction of the ore body are completely consistent with the layered approach filling mining method; the approach of each layer is divided into the side edge approach on the boundary of the surrounding rock and the ore body and the inner approach of the ore body , the operation method of each stratified approach is to mine and close the side-side access in the order of zigzag, and follow the principle of gradually advancing from the two sides of the ore body to the middle of the ore body to mine and fill the internal access. If it is necessary to reserve the route for the CO ₂ storage vacancy (2) or the high-porosity CO ₂ storage waste rock filling area (3), skip this route first, and mine and fill the next route. When it is necessary to reserve CO ₂ storage vacancy (2) or high-porosity CO ₂ storage waste rock filling area (3) is filled on both sides of the route, and then the route is mined, and then left empty or filled with waste rock to form CO ₂ Storage empty area (2) or high porosity _CO2 storage waste rock filling area (3). 3. A kind of goaf carbon sequestration method based on layered approach tailings cemented filling mining according to claim 1, characterized in that: Use airtight material (1) to seal the sides except the connecting roadway as follows: use high-strength tailings cemented filling body (5) to fill the outer side of the side road near the surrounding rock, and the side road to be close to the ore body The inside of the inner side is filled with airtight material (1), and 1/10 of the side road width is reserved between the airtight material (1) and the unmined ore block inside as an isolation space for the impact of ore collapse, protecting the two sides of the filling body and sealing Material; The method of sealing the side roadway with airtight material (1) is as follows: fill the inner side of the layered roadway (11) near the ore body with airtight material (1), and fill the inner side of the layered roadway (11) near the surrounding rock The outer side of the side is filled with high-strength tailings cemented filling body (5), and the stope contact roadway (10) is all filled with tailings cemented filling body (4). 4. A kind of goaf carbon sequestration method based on layered approach tailings cemented filling mining according to claim 1, characterized in that: The top layer and the bottom layer of the ore body (12) need to be equipped with an airtight artificial false roof (6) and an airtight artificial false bottom (7). An airtight artificial false roof (6) is installed on the top of each middle section. If the upward layered approach filling method is selected for mining, an airtight artificial false bottom (7) needs to be installed at the bottom of each middle section. The artificial false roof (6) and the airtight artificial bottom (7), combined with the edge airtight material (1) and the high-strength tailings cemented filling body (5), form a stable carbon sequestration unit structure with the middle section as the unit. 5. A goaf carbon sequestration method based on layered tailings cemented filling mining according to claim 1, characterized in that: _the captured CO comes from the mining enterprise dressing and smelting plant, or electricity, cement, Four major emission sources of iron and steel and chemical industry; the captured CO ₂ passes through the surface CO ₂ pumping station near the return air shaft, and connects with the stope through the pipeline along the return air shaft and return airway to the segmented transportation lane (8) The _CO2 pipeline (9) at the intersection of the lane (10) injects _CO2 into the _CO2 sequestration empty area (2) or the waste rock filling area (3) to prevent the _CO2 pipeline (9) from leaking and polluting the fresh air flow. 6. A goaf carbon sequestration method based on layered tailings cemented backfill mining according to claim 2, characterized in that: the _CO2 delivery pressure of the _CO2 pipeline (9) is controlled to maintain side gas dense material (1) and high-strength tailings cemented backfill (5) are stable, and at the same time partially tear the CO ₂ storage void (2) or the CO ₂ storage waste rock backfill (3) surrounding tailings cemented backfill (4) Among them, the pressure of gaseous CO ₂ can be as low as below 1 MPa, which is suitable for the mined-out area where the buried depth of the ore body (12) is less than 100 m, and the ground stress and surrounding rock strength are low. The increase of stress and surrounding rock strength can gradually increase the pressure of CO ₂ charged. When the ground temperature of the goaf is greater than 31 ℃ and the mining depth is greater than 800 m, it is considered to store CO ₂ in a supercritical state. 7. A goaf carbon sequestration method based on layered tailings cemented filling mining according to claim 1, characterized in that: the intersecting stope roadway (10) and segmental transportation roadway (8) The CO ₂ pipeline (9) near the point is equipped with a CO ₂ pressure sensor, an airtight valve and a flange interface; when the CO ₂ injection operation is completed, close the airtight valve, loosen the flange interface, and then seal the interface with the flange The pipeline connected to the CO ₂ storage empty area (2) or the CO ₂ storage waste rock filling area (3) is used to recover the CO ₂ pipeline on the current section of the transportation lane and reuse it on the next section of the transportation lane, and the surface CO ₂ The remaining _CO2 pipelines from the pumping station to the current section remain unchanged and extend down to the next section; the _CO2 pressure sensor monitors the _CO2 storage empty area (2) or the _CO2 storage waste rock filling area (3 ) within the _CO2 pressure change. 8. A goaf carbon sequestration method based on layered tailings cemented filling mining according to claim 1, characterized in that: the surrounding rock near the side of the ore body is set at intervals of a segmental height distance A CO ₂ concentration sensor for early warning of CO ₂ leakage; if there is no obvious CO ₂ leakage during the storage period, and the CO ₂ pressure sensor for detecting the CO ₂ storage empty area (2) or the CO ₂ storage waste rock filling area (3) reads slowly When the CO ₂ pressure drops to 75% of the set pressure, the air-tight valve and flange interface can be used to reconnect the CO ₂ gas _source to store the air for CO ₂ Zone (2) or CO ₂ sequestration waste rock fill zone (3) for repressurization. 9. A goaf carbon sequestration method based on layered tailings cemented filling mining according to claim 1, characterized in that the tailings cemented filling slurry used in the tailings cemented filling body (4) includes Mine tailings, Portland cement or mixed with fly ash, steel slag composite Portland cement, water, additives, filling slurry concentration greater than 70%, 3-day strength greater than 1MPa; tailings used in the downward layered filling method The lime-sand mass ratio in the cemented backfill (4) is greater than 1:6, and the strength is greater than 3.5 MPa in 28 days; the lime-sand mass ratio in the tailings cemented backfill (4) of the upward layered filling method is greater than 1:8, and the strength is greater than 3.5 MPa in 28 days. The strength is greater than 2 MPa; the lime-sand mass ratio in the high-strength tailings cemented filling body (5) on the outside of the filling side road and the layered connection roadway is greater than 1:4, and the 28-day strength is greater than 5 MPa. 10. A goaf carbon sequestration method based on layered tailings cemented filling mining according to claim 1, characterized in that: The airtight material (1) includes airtight concrete, asphalt-based airtight filling material, and mining filling sealing material; The airtight artificial false roof (6) and airtight artificial bottom (7) include airtight concrete, a composite structure of concrete plus asphalt-based airtight filler, and a composite structure of concrete plus ore-filling sealing material.

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