Recovery method of open-pit coal mine by filling

Abstract

The application discloses a kind of open coal mine filling recovery method, including obtaining the cavity position of goaf.Based on cavity position arrangement filling hole, filling hole includes multiple aggregate holes and multiple cementing holes, multiple aggregate holes are distributed at cavity position with interval, cementing hole is located in the middle of multiple aggregate holes so that multiple aggregate holes are arranged around the circumference of cementing hole, and each aggregate hole is adjacent to at least one cementing hole.Setting according to the filling strength requirement configuration aggregate and cementing material, aggregate includes preset ratio of coal gangue and straw, cementing material includes preset ratio of loess and cement.Aggregate is sent to cavity by aggregate hole.Cementing material is injected into cavity by cementing hole until cementing material flows out from adjacent aggregate hole.The application reduces the filling cost, realizes gangue and straw resource utilization, filling body strength is controllable, and adapts to the demand of subsequent open stripping.

Description

Technical Field

[0001] This invention belongs to the field of coal mining technology, and specifically relates to a method for backfilling and remining in open-pit coal mines. Background Technology

[0002] Coal mine backfilling and remining processes are mostly used in underground coal mines, with fewer applications in open-pit coal mines. The existing technologies employ a treatment approach of "first backfilling the goaf with paste, then setting up the underground fully mechanized mining face," which results in high costs, low efficiency, and limited applicability for open-pit mine backfilling / stripping processes. Summary of the Invention

[0003] This invention is based on the inventor's discoveries and understanding of the following facts and problems:

[0004] The inventors recognized that the paste-like materials in related technologies require a high concentration (>80%) of gangue powder mixed with cement, resulting in high crushing energy consumption and poor fluidity (short diffusion radius), making it difficult to fill small cracks in the roadway. Open-pit mining requires secondary stripping and backfilling, and the cement-based materials in related technologies have excessively high strength (>5MPa), leading to increased wear and tear on mining equipment.

[0005] The inventors also recognized that the materials in the related technology have environmental defects. Because they rely on fly ash (pH>9) as a cementing component, they violate the pH limit (6-9) requirements of general industrial solid waste storage and landfill pollution control standards, and pose a risk of groundwater pollution.

[0006] The inventors also recognized that related technologies do not fully utilize resources. The coal-rich areas of Shanxi, Shaanxi, and Inner Mongolia contain abundant loess (including loess stripped from open-pit mines), which has good cementing properties and can replace some cement, reducing backfilling costs. The region also has a large straw production; incorporating it into the backfill can further improve its strength, reduce the amount of cementitious material, and lower backfilling costs. Related technologies do not effectively utilize these resources, creating an environmental burden.

[0007] The present invention aims to at least partially solve one of the technical problems in the related art.

[0008] Therefore, embodiments of the present invention propose a method for backfilling and remining in open-pit coal mines that improves resource utilization and achieves resource integration.

[0009] The open-pit coal mine backfilling and re-mining method of this invention includes:

[0010] Obtain the location of the cavity in the goaf;

[0011] Filling holes are arranged based on the cavity location. The filling holes include multiple aggregate holes and multiple bonding holes. The multiple aggregate holes are distributed at intervals at the cavity location. The bonding holes are located in the middle of the multiple aggregate holes so that the multiple aggregate holes are arranged circumferentially around the bonding holes. Each aggregate hole is adjacent to at least one bonding hole.

[0012] Aggregates and binders are configured according to the filling strength requirements. The aggregates include coal gangue and straw in a preset ratio, and the binders include loess and cement in a preset ratio.

[0013] Aggregate is fed into the cavity through the aggregate holes;

[0014] The binder is injected into the cavity through the bonding holes until it flows out from the adjacent aggregate holes.

[0015] The open-pit coal mine backfilling and re-mining method of this invention uses loess and straw to replace part of the backfilling material, reducing backfilling costs and realizing the resource utilization of gangue and straw. By arranging the backfilling holes and distributing the aggregate and binder, the compactness of the backfilling cavity in the roadway can be improved, while the strength of the backfill body can be controlled, adapting to the needs of subsequent open-pit stripping.

[0016] In some embodiments, the filling hole includes a plurality of filling hole groups, each filling hole group including a plurality of aggregate holes and a cementing hole, and adjacent filling hole groups share a portion of the aggregate holes;

[0017] In a group of filling holes, the number of aggregate holes is 2 to 6, and the aggregate holes are arranged circumferentially around the cementing holes.

[0018] In some embodiments, the diameter of the aggregate pores is 0.6m to 1m, and the diameter of the cementing pores is 0.15m to 0.45m.

[0019] In some embodiments, the step of arranging filling holes based on the cavity location includes:

[0020] Obtain the span of the cavity and determine whether the span of the cavity is greater than a first threshold.

[0021] If not, the spacing between adjacent filling holes is 4.5m to 5.5m;

[0022] If so, the spacing between adjacent filling holes is 6m to 8m.

[0023] In some embodiments, the first threshold is 4m to 6m.

[0024] In some embodiments, when there is broken overburden at the top of the cavity, the spacing between adjacent filling holes is 3.5m to 4m.

[0025] In some embodiments, the coal gangue has a particle size of less than or equal to 80 mm, the straw has a length of 5 cm to 10 cm, and the amount of straw in the aggregate accounts for 2.5% to 3.5% of the mass of the coal gangue.

[0026] In some embodiments, the viscosity of the binder is 35s to 40s, which is the Marsh funnel viscosity.

[0027] In some embodiments, the binder comprises the following raw materials in parts by weight: 80 to 90 parts loess, 10 to 20 parts cement and an appropriate amount of water, wherein the loess in the binder has a particle size of less than or equal to 2 mm, and the water-cement ratio of the binder is 0.7 to 0.8.

[0028] And / or, the step involves injecting adhesive into the cavity through the bonding holes at a pressure of 0.3 MPa to 0.5 MPa.

[0029] In some embodiments, the step of obtaining the location of the cavity in the goaf includes:

[0030] Obtain historical mining data;

[0031] Ground-penetrating radar and boreholes were used to conduct stratigraphic exploration and obtain stratigraphic data;

[0032] A three-dimensional geological model was constructed based on the historical mining data and stratigraphic data, and the location of cavities was marked. Attached Figure Description

[0033] Figure 1 This is a flowchart of the open-pit coal mine backfilling and re-mining method according to an embodiment of the present invention.

[0034] Figure 2 This is a schematic diagram of the arrangement of filling holes in an embodiment of the present invention.

[0035] Figure 3 This is a schematic diagram of the filling of aggregates and binders in an embodiment of the present invention.

[0036] Figure label:

[0037] 1. Cavity;

[0038] 21. Aggregate pores; 22. Cementing pores;

[0039] 3. Aggregate; 31. Coal gangue; 32. Straw;

[0040] 4. Binder;

[0041] 5. Strata;

[0042] 6. Coal pillar. Detailed Implementation

[0043] Embodiments of the present invention are described in detail below, examples of which are illustrated in the accompanying drawings. The embodiments described below with reference to the accompanying drawings are exemplary and intended to explain the present invention, and should not be construed as limiting the present invention.

[0044] See Figures 1 to 3 The open-pit coal mine backfilling and re-mining method of this invention includes:

[0045] S101. Obtain the location of cavity 1 in the goaf. The location of cavity 1 in the goaf can be obtained from historical mining drawings, written records, and other data. Alternatively, it can be obtained through geological surveys to acquire information such as the outline and span of cavity 1. The degree of fracturing of the overlying rock at the top of cavity 1 can also be evaluated, and a three-dimensional model of the corresponding area can be created to obtain a three-dimensional geological model. This will facilitate the subsequent arrangement of filling holes based on the location of cavity 1.

[0046] S102. Filling holes are arranged based on the location of cavity 1. The filling holes include multiple aggregate holes 21 and multiple cementing holes 22. The aggregate holes 21 are used to fill the cavity 1 with aggregate layer 3 material, which has tensile and compressive strength. The cementing holes 22 are used to fill the cavity 1 with cementing layer material, which has permeability and cementing properties. It can penetrate into the gaps of the aggregate layer 3 material and the fissures of the rock strata surrounding the cavity 1, so that the filling body can be consolidated, increasing the strength of the filling body and connecting it with the surrounding rock strata.

[0047] Multiple aggregate holes 21 are spaced apart at the cavity 1. The aggregate holes 21 can be arranged in an approximately rectangular array above the cavity 1. After the multiple aggregate holes 21 are filled with the aggregate 3 layers of material, they can more evenly cover the various areas of the cavity 1. A binder hole 22 is located in the middle of the multiple aggregate holes 21 so that the multiple aggregate holes 21 are arranged circumferentially around the binder hole 22, and each aggregate hole 21 is adjacent to at least one binder hole 22. After the aggregate 3 layers of material are filled, binder 4 is injected into the cavity 1 through the binder hole 22. The binder 4 diffuses into the gaps within the aggregate holes 21 and mixes with the aggregate 3. As the binder 4 further diffuses, it can mix evenly with the aggregate 3 below the multiple circumferential aggregate holes 21, improving the uniformity of the mixture of aggregate 3 and binder 4.

[0048] S103. Aggregate 3 and binder 4 are configured according to the filling strength requirements. Aggregate 3 includes coal gangue 31 and straw 32 in a preset ratio, and binder 4 includes loess and cement in a preset ratio. In order to simultaneously adapt to the filling strength of the cavity 1 in the mining area and the subsequent open-pit stripping mining, this embodiment of the invention uses coal gangue 31 and straw 32 as aggregate 3 to replace the paste material in related technologies, and uses binder 4 and aggregate 3 to fill separately, which improves the filling effect and reduces the filling cost.

[0049] In related technologies, the paste material uses a mixture of gangue powder and cement. However, gangue crushing is energy-intensive, the paste material has poor fluidity and a small diffusion radius, making it difficult to fill small cracks, resulting in unsatisfactory filling effects and high filling costs. Compared to related technologies, the coal gangue 31 in the aggregate 3 of this embodiment requires a lower crushing particle size, reducing crushing energy consumption. The coal gangue 31 is mixed with straw 32, which can improve the tensile strength of the gangue aggregate 3. The binder 4 uses loess instead of more than 70% of the cement in related technologies, reducing the overall cost by 45% to 60%. The process cost of related technologies is 50 to 80 yuan per cubic meter, while the process cost of this embodiment can be reduced to 30 to 40 yuan per cubic meter. The binder 4 in this embodiment has good fluidity, allowing for better mixing with the aggregate 3 and filling dense, small cracks, simultaneously achieving resource utilization of both gangue and straw 32. In the embodiments of the present invention, the backfill body after filling and consolidation has stable structural strength and is suitable for the needs of subsequent open-pit stripping and mining operations, thereby improving the efficiency of subsequent operations.

[0050] S104. Aggregate 3 is fed into cavity 1 through aggregate holes 21. Aggregate 3 is fed into cavity 1 sequentially through aggregate holes 21. Aggregate 3 has a certain angle of repose. By reasonably controlling the spacing between adjacent aggregate holes 21, the feeding amount of aggregate 3 and the uniformity of the distribution of aggregate 3 on the horizontal plane can be ensured, thereby meeting the filling requirements.

[0051] S105. Cementing material 4 is injected into cavity 1 through cementing holes 22 until it flows out from adjacent aggregate holes 21. During the injection of cementing material 4 into cavity 1 through cementing holes 22, it mixes and blends with aggregate 3, achieving a mixture of cementing material 4 and aggregate 3. Cementing material 4 also enters the fissures of the surrounding rock strata, thus cementing the rock strata together. Cementing material 4 has good fluidity, and after mixing with aggregate 3, the solidified filling structure is stable, exhibiting good compressive and tensile strength.

[0052] In steps S104 and S105, aggregate 3 can be fed first, followed by binder 4. Alternatively, aggregate 3 and binder 4 can be injected alternately in multiple batches to improve the uniformity of mixing between the two.

[0053] The open-pit coal mine backfilling and re-mining method of this invention uses loess and straw 32 to replace part of the backfilling material, reducing backfilling costs and realizing the resource utilization of gangue and straw 32. By arranging the backfilling holes and distributing the aggregate 3 and binder 4, the compactness of the backfilling in the roadway cavity 1 can be improved, while the strength of the backfilling body is controllable, adapting to the needs of subsequent open-pit stripping.

[0054] The following describes some specific embodiments of the open-pit coal mine backfilling and re-mining method of the present invention.

[0055] See Figures 1 to 3 A method for backfilling and remining in open-pit coal mines, comprising:

[0056] S101. Obtain the location of cavity 1 in the goaf. Specifically, obtain historical mining data. Based on historical mining drawings, written records, and other data, obtain information about cavity 1 in the mining area. Then, use ground-penetrating radar and boreholes to explore stratigraphy 5, obtaining stratigraphy 5 data. After processing the stratigraphy 5 data, obtain the boundary, span, relative height of the roof and floor, and the development of fractures in the roof overburden of cavity 1. Simultaneously, the location of coal pillar 6 can be preliminarily determined. Based on the historical mining data and stratigraphy 5 data, construct a three-dimensional geological model and mark the location of cavity 1.

[0057] This invention embodiment obtains information such as the outline and span of cavity 1 after geological survey, evaluates the degree of fracturing of the overlying rock at the top of cavity 1, and then performs three-dimensional modeling of the corresponding area to obtain a three-dimensional geological model, so as to facilitate the subsequent arrangement of filling holes according to the location of cavity 1.

[0058] S102. Filling holes are arranged based on the location of cavity 1. The filling holes include multiple aggregate holes 21 and multiple cementing holes 22. The aggregate holes 21 are used to fill the cavity 1 with aggregate layer 3 material, which has tensile and compressive strength. The cementing holes 22 are used to fill the cavity 1 with cementing layer material, which has permeability and cementing properties. It can penetrate into the gaps of the aggregate layer 3 material and the fissures of the rock strata surrounding the cavity 1, so that the filling body can be consolidated, increasing the strength of the filling body and connecting it with the surrounding rock strata.

[0059] Multiple aggregate holes 21 are spaced apart at the cavity 1. The aggregate holes 21 can be arranged in an approximately rectangular array above the cavity 1. After the multiple aggregate holes 21 are filled with the aggregate 3 layers of material, they can more evenly cover the various areas of the cavity 1. A binder hole 22 is located in the middle of the multiple aggregate holes 21 so that the multiple aggregate holes 21 are arranged circumferentially around the binder hole 22, and each aggregate hole 21 is adjacent to at least one binder hole 22. After the aggregate 3 layers of material are filled, binder 4 is injected into the cavity 1 through the binder hole 22. The binder 4 diffuses into the gaps within the aggregate holes 21 and mixes with the aggregate 3. As the binder 4 further diffuses, it can mix evenly with the aggregate 3 below the multiple circumferential aggregate holes 21, improving the uniformity of the mixture of aggregate 3 and binder 4.

[0060] Specifically, the filling hole includes multiple filling hole groups, each filling hole group includes multiple aggregate holes 21 and one cementing hole 22, and adjacent filling hole groups share some aggregate holes 21.

[0061] The number of aggregate holes 21 is 2 to 6, and multiple aggregate holes 21 are arranged circumferentially around the cementing holes 22. For example, a partial filling hole group is arranged in a cavity 1 with a relatively small span, and each filling hole group has two aggregate holes 21 and one cementing hole 22, with the cementing hole 22 located between two aggregate holes 21. As another example, a partial filling hole group is located in a cavity 1 with a relatively large span, then each filling hole group has four aggregate holes 21 and one cementing hole 22, with the four aggregate holes 21 arranged in a rectangular array, and the cementing hole 22 located in the middle of the four aggregate holes 21, thus making the filling hole group quincunx-shaped.

[0062] In this embodiment of the invention, the diameter of the aggregate hole 21 is 0.6m to 1m, for example, the diameter of the aggregate hole 21 is 0.6m, 0.66m, 0.7m, 0.8m, or 1m, and the diameter of the cementing hole 22 is 0.15m to 0.45m, for example, the diameter of the cementing hole 22 is 0.15m, 0.17m, 0.25m, 0.3m, 0.35m, or 0.45m. If the diameters of the aggregate hole 21 and the cementing hole 22 are too large, it increases the construction difficulty and workload, affecting the construction progress. If the diameters of the aggregate hole 21 and the cementing hole 22 are too small, it can easily lead to a limited feeding speed of the aggregate 3 or the cementitious material 4, which is not conducive to the rapid filling of materials.

[0063] To more rationally arrange the filling holes above cavity 1, the spacing between adjacent filling holes can be determined based on the span of cavity 1. Specifically, the span of cavity 1 is obtained, and it is determined whether the span of cavity 1 is greater than a first threshold. The first threshold is 4m to 6m. For example, the first threshold can be 4m, 4.4m, 4.8m, 5.5m, or 6m.

[0064] Preferably, the first threshold value in this embodiment is 5m. When the span of cavity 1 is less than or equal to 5m, the spacing between adjacent filling holes can be set to 4.5m to 5.5m. For example, the distance between adjacent filling holes is 4.5m, 4.8m, 5m, or 5.5m. When the span of cavity 1 is greater than 5m, the spacing between adjacent filling holes is 6m to 8m. For example, the spacing between adjacent filling holes is 6m, 6.3m, 6.8m, 7.6m, or 8m.

[0065] During the preliminary geological exploration, if fractured overburden is found at the top of cavity 1, the spacing between adjacent filling holes should be increased to 3.5m to 4m. For example, the spacing between adjacent filling holes would be 3.5m, 3.7m, or 4m.

[0066] The present invention, through the design of the filling hole spacing, can improve construction efficiency and filling efficiency while ensuring the stability of the filling material quality. It can also better bind and mix the aggregate 3 and the binder 4, making it highly practical.

[0067] S103. Aggregate 3 and binder 4 are configured according to the filling strength requirements. Aggregate 3 includes coal gangue 31 and straw 32 in a preset ratio, and binder 4 includes loess and cement in a preset ratio. In order to simultaneously adapt to the filling strength of the cavity 1 in the mining area and the subsequent open-pit stripping mining, this embodiment of the invention uses coal gangue 31 and straw 32 as aggregate 3 to replace the paste material in related technologies, and uses binder 4 and aggregate 3 to fill separately, which improves the filling effect and reduces the filling cost.

[0068] In this embodiment of the invention, the coal gangue 31 has a particle size of less than or equal to 80 mm. Compared to related technologies that require grinding coal gangue 31 into small particles of less than or equal to 10 mm, this embodiment of the invention can reduce energy consumption costs by more than 40% in the processing of coal gangue 31. The straw 32 has a length of 5 cm to 10 cm and can be crushed by a pulverizer. The amount of straw 32 in the aggregate 3 accounts for 2.5% to 3.5% of the mass of coal gangue 31. It is mixed evenly during use and then placed into the cavity 1 after being evenly mixed.

[0069] Cementitious material 4 comprises the following raw materials in parts by weight: 80 to 90 parts loess, 10 to 20 parts cement, and an appropriate amount of water. The loess in cementitious material 4 has a particle size of less than or equal to 2 mm. After crushing and sieving, the loess with a particle size of less than 2 mm is selected and mixed with cement, and water is added for stirring. The water-cement ratio of cementitious material 4 is 0.7 to 0.8. For example, cementitious material 4 contains 85 parts by weight of loess and 15 parts by weight of cement. PO 42.5 cement can be used.

[0070] The binder 4 prepared after mixing and stirring was tested for viscosity using a Marshall funnel, and the parameter value met the requirement of 35s to 40s, ensuring that it has good flowability and bonding performance.

[0071] In related technologies, the paste material uses a mixture of gangue powder and cement. However, gangue crushing is energy-intensive, the paste material has poor fluidity and a small diffusion radius, making it difficult to fill small cracks, resulting in unsatisfactory filling effects and high filling costs. Compared to related technologies, the coal gangue 31 in the aggregate 3 of this embodiment requires a lower crushing particle size, reducing crushing energy consumption. The coal gangue 31 is mixed with straw 32, which can improve the tensile strength of the gangue aggregate 3. The binder 4 uses loess instead of more than 70% of the cement in related technologies, reducing the overall cost by 45% to 60%. The process cost of related technologies is 50 to 80 yuan per cubic meter, while the process cost of this embodiment can be reduced to 30 to 40 yuan per cubic meter. The binder 4 in this embodiment has good fluidity, allowing for better mixing with the aggregate 3 and filling dense, small cracks, simultaneously achieving resource utilization of both gangue and straw 32. In the embodiments of the present invention, the backfill body after filling and consolidation has stable structural strength and is suitable for the needs of subsequent open-pit stripping and mining operations, thereby improving the efficiency of subsequent operations.

[0072] S104. Aggregate 3 is fed into cavity 1 through aggregate holes 21. Aggregate 3 is fed into cavity 1 sequentially through aggregate holes 21. Aggregate 3 has a certain angle of repose. By reasonably controlling the spacing between adjacent aggregate holes 21, the feeding amount of aggregate 3 and the uniformity of the distribution of aggregate 3 on the horizontal plane can be ensured, thereby meeting the filling requirements.

[0073] S105. Cementitious material 4 is injected into cavity 1 through cementing holes 22 at a pressure of 0.3 MPa to 0.5 MPa until it flows out from adjacent aggregate holes 21. During the injection of cementitious material 4 into cavity 1 through cementing holes 22, it mixes and blends with aggregate 3, achieving a mixture of cementitious material 4 and aggregate 3. Cementitious material 4 also enters the fissures of the surrounding rock strata, thus cementing the rock strata together. Cementitious material 4 has good fluidity, and after mixing with aggregate 3, the solidified filling structure has good stability and excellent compressive and tensile strength.

[0074] In steps S104 and S105, aggregate 3 can be fed first, followed by binder 4. Alternatively, aggregate 3 and binder 4 can be injected alternately in multiple batches to improve the uniformity of mixing between the two.

[0075] After the grouting of aggregate 3 and binder 4 is completed, the filling material is left to cure for 7 days. At this time, the filling material is solidified and the uniaxial compressive strength reaches more than 1MPa before the mining operation is allowed.

[0076] The open-pit coal mine backfilling and re-mining method of this invention uses loess and straw to replace part of the backfilling material, reducing backfilling costs and realizing the resource utilization of gangue and straw. By arranging the backfilling holes and distributing the aggregate and binder, the compactness of the backfilling cavity in the roadway can be improved, while the strength of the backfill body can be controlled, adapting to the needs of subsequent open-pit stripping.

[0077] Compared to the filling density of 75-85% in related technologies, the filling density of the present invention is 92-95%, which can prevent water and gas accumulation in the goaf and provide higher safety.

[0078] The strength of the filling body in this embodiment of the invention can reach 1.2 MPa. By adjusting the ratio of straw to coal gangue and the ratio of loess to cement, the strength of the filling body can be controlled and adjusted within a range of 1-5 MPa, which is suitable for open-pit mining, can reduce stripping difficulty and improve mining efficiency.

[0079] The overall cost is significantly reduced in this embodiment of the invention. By reducing the energy consumption of gangue crushing and replacing cement / fly ash with open-pit stripping of loess, the backfilling cost is reduced to 30 yuan / m³. 3 ~40 yuan / m 3 This reduces costs by nearly 50%.

[0080] Meanwhile, the embodiments of the present invention can also bring additional benefits, with each cubic meter of backfill absorbing 1.8 tons of coal gangue and 0.05 tons of straw. The surface subsidence after backfilling is less than 3 cm / year, meeting the safety requirements for open-pit mining equipment.

[0081] In the description of this invention, it should be understood that the terms "center," "longitudinal," "lateral," "length," "width," "thickness," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," "clockwise," "counterclockwise," "axial," "radial," and "circumferential" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing this invention and simplifying the description, and are not intended to indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this invention.

[0082] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one of that feature. In the description of this invention, "a plurality of" means at least two, such as two, three, etc., unless otherwise explicitly specified.

[0083] In this invention, unless otherwise explicitly specified and limited, the terms "installation," "connection," "linking," and "fixing," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection, an electrical connection, or a connection that allows communication between them; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components, unless otherwise explicitly limited. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0084] In this invention, unless otherwise explicitly specified and limited, "above" or "below" the second feature can mean that the first feature is in direct contact with the second feature, or that the first feature is in indirect contact with the second feature through an intermediate medium. Furthermore, "above," "over," and "on top" of the second feature can mean that the first feature is directly above or diagonally above the second feature, or simply that the first feature is at a higher horizontal level than the second feature. "Below," "below," and "under" the second feature can mean that the first feature is directly below or diagonally below the second feature, or simply that the first feature is at a lower horizontal level than the second feature.

[0085] In this invention, the terms "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., refer to a specific feature, structure, material, or characteristic described in connection with that embodiment or example, which is included in at least one embodiment or example of the invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples. Moreover, without contradiction, those skilled in the art can combine and integrate the different embodiments or examples described in this specification, as well as the features of different embodiments or examples.

[0086] Although embodiments of the present invention have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting the present invention. Those skilled in the art can make changes, modifications, substitutions and variations to the above embodiments within the scope of the present invention.

Claims

1. A method for backfilling and remining in open-pit coal mines, characterized in that, include: Obtain the location of the cavity in the goaf; Filling holes are arranged based on the cavity location. The filling holes include multiple aggregate holes and multiple bonding holes. The multiple aggregate holes are distributed at intervals at the cavity location. The bonding holes are located in the middle of the multiple aggregate holes so that the multiple aggregate holes are arranged circumferentially around the bonding holes. Each aggregate hole is adjacent to at least one bonding hole. Aggregates and binders are configured according to the filling strength requirements. The aggregates include coal gangue and straw in a preset ratio, and the binders include loess and cement in a preset ratio. Aggregate is fed into the cavity through the aggregate holes; The binder is injected into the cavity through the cementing holes at a pressure of 0.3 MPa to 0.5 MPa until the binder flows out from the adjacent aggregate holes; The filling hole includes multiple filling hole groups, each filling hole group includes multiple aggregate holes and one cementing hole, and adjacent filling hole groups share a portion of the aggregate holes; In a group of filling holes, the number of aggregate holes is 2 to 6, and the aggregate holes are arranged circumferentially around the cementing holes; The coal gangue has a particle size of less than or equal to 80 mm, the straw has a length of 5 cm to 10 cm, and the amount of straw in the aggregate accounts for 2.5% to 3.5% of the mass of the coal gangue. The binder comprises the following raw materials in parts by weight: 80 to 90 parts loess, 10 to 20 parts cement and an appropriate amount of water. The loess in the binder has a particle size of less than or equal to 2 mm, and the water-cement ratio of the binder is 0.7 to 0.

8.

2. The open-pit coal mine backfilling and re-mining method according to claim 1, characterized in that, The diameter of the aggregate pores is 0.6m to 1m, and the diameter of the cementing pores is 0.15m to 0.45m.

3. The open-pit coal mine backfilling and re-mining method according to claim 1 or 2, characterized in that, The step involves arranging filling holes based on the cavity location, including: Obtain the span of the cavity and determine whether the span of the cavity is greater than a first threshold. If not, the spacing between adjacent filling holes is 4.5m to 5.5m; If so, the spacing between adjacent filling holes is 6m to 8m.

4. The open-pit coal mine backfilling and re-mining method according to claim 3, characterized in that, The first threshold is 4m to 6m.

5. The open-pit coal mine backfilling and re-mining method according to claim 3, characterized in that, When there is broken overburden at the top of the cavity, the spacing between adjacent filling holes is 3.5m to 4m.

6. The method for backfilling and remining in open-pit coal mines according to claim 1, characterized in that, The viscosity of the binder meets the Marsh funnel viscosity requirement of 35s to 40s.

7. The open-pit coal mine backfilling and re-mining method according to claim 1, characterized in that, The steps to obtain the location of the cavity in the goaf include: Obtain historical mining data; Ground-penetrating radar and boreholes were used to conduct stratigraphic exploration and obtain stratigraphic data; A three-dimensional geological model was constructed based on the historical mining data and stratigraphic data, and the location of cavities was marked.

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