Open pit coal mine filling and re-mining method

Abstract

The invention discloses a filling and re-mining method for an open pit coal mine. The method comprises the following steps: acquiring a cavity position of a goaf; filling holes are formed based on the positions of the cavities, the filling holes comprise a plurality of aggregate holes and a plurality of cementing holes, the aggregate holes are distributed in the positions of the cavities at intervals, the cementing holes are located in the middles of the aggregate holes so that the aggregate holes can be formed in the circumferential direction of the cementing holes, and each aggregate hole is adjacent to at least one cementing hole. Aggregate and a cementing material are prepared according to the filling strength requirement, the aggregate comprises coal gangue and straw in a preset proportion, and the cementing material comprises loess and cement in a preset proportion. And aggregate is fed into the cavity through the aggregate holes. And cementing materials are injected into the cavity through the cementing holes until the cementing materials flow out of the adjacent aggregate holes. According to the method, the filling cost is reduced, resource utilization of the gangue and the straw is achieved, the strength of the filling body is controllable, and the requirement for follow-up open-air stripping is met.

Description

Technical Field

[0001] The invention belongs to the technical field of coal mining, and in particular relates to a filling and re-mining method for an open-pit coal mine. Background Art

[0002] Coal mine backfilling / backfilling processes are primarily used in underground coal mines, with few applications targeting open-pit coal mines. Related technologies employ a "paste filling" approach, prioritizing the deployment of underground fully mechanized mining faces. This backfilling / backfilling / backfilling process is costly, inefficient, and insufficiently applicable to open-pit mines. Summary of the Invention

[0003] The present invention is based on the inventor's discovery and understanding of the following facts and problems:

[0004] The inventors recognized that the paste materials used in related art 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 tunnels. Open-pit mining requires secondary stripping of the fill material, and the cement-based materials used in related art are too strong (>5MPa), resulting in increased wear and tear of mining equipment.

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

[0006] The inventors also recognized that related art techniques underutilize resources. The coal-rich regions of Shanxi, Shaanxi, and Inner Mongolia contain a large amount of loess (including loess stripped from open-pit mines), which possesses excellent cementitious properties and can replace some cement, reducing backfill costs. The region also produces a significant amount of straw, which, when incorporated into backfill, can further enhance backfill strength, reduce binder usage, and lower backfill costs. However, related art techniques fail to effectively utilize these resources, resulting in an environmental burden.

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

[0008] To this end, an embodiment of the present invention proposes 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 according to an embodiment of the present invention comprises:

[0010] Get the cavity position of the goaf;

[0011] Arranging filling holes based on the cavity position, the filling holes including a plurality of aggregate holes and a plurality of cementing holes, the plurality of aggregate holes being distributed at intervals at the cavity position, the cementing holes being located in the middle of the plurality of aggregate holes so that the plurality of aggregate holes are arranged around the circumference of the cementing holes, and each of the aggregate holes is disposed adjacent to at least one of the cementing holes;

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

[0013] delivering aggregate into the cavity through the aggregate holes;

[0014] The cementing material is injected into the cavity through the cementing holes until the cementing material flows out from the adjacent aggregate holes.

[0015] The open-pit coal mine backfilling and remining method of the present invention uses loess and straw to replace some of the backfill materials, reducing backfill costs and realizing resource utilization of waste rock and straw. By arranging the filling holes and distributing the aggregate and binder, the density of the filling in the tunnel cavity can be improved, while the filling strength can be controlled to meet the needs of subsequent open-pit stripping.

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

[0017] In one group of the filling holes, the number of the aggregate holes is 2 to 6, and the plurality of aggregate holes are arranged around the circumference of the cementing hole.

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

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

[0020] Obtaining the span of the cavity, and determining 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 distance 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 3.5 m to 4 m.

[0025] In some embodiments, the particle size of the coal gangue is less than or equal to 80 mm, the length of the straw is 5 cm to 10 cm, and the straw content 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 satisfies a Marsh funnel viscosity of 35s to 40s.

[0027] In some embodiments, the binder comprises the following raw materials in parts by weight: 80 to 90 parts of loess, 10 to 20 parts of 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 is to inject the binder into the cavity through the binder hole, and inject the binder into the cavity through the binder hole at a pressure of 0.3 MPa to 0.5 MPa.

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

[0030] Obtain historical mining data;

[0031] Use ground penetrating radar and drill holes to conduct stratigraphic surveys and obtain stratigraphic data;

[0032] A three-dimensional geological model is constructed based on the historical mining data and the stratigraphic data, and the cavity locations are marked. BRIEF DESCRIPTION OF THE DRAWINGS

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

[0034] Figure 2 Schematic diagram of the arrangement of filling holes in an embodiment of the present invention.

[0035] Figure 3 Schematic diagram of filling of aggregate and binder in an embodiment of the present invention.

[0036] Reference numerals:

[0037] 1. Cavity;

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

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

[0040] 4. Binder;

[0041] 5. Strata;

[0042] 6. Coal pillar. DETAILED DESCRIPTION

[0043] The embodiments of the present invention are described in detail below, and examples of the embodiments are shown in the accompanying drawings. The embodiments described below with reference to the accompanying drawings are exemplary and intended to be used to explain the present invention, but should not be understood as limiting the present invention.

[0044] See also Figures 1 to 3 The open-pit coal mine backfilling and re-mining method according to an embodiment of the present invention comprises:

[0045] S101. Obtain the location of cavity 1 in the goaf. The location of cavity 1 in the goaf can be obtained based on historical mining drawings, written records, and other data. Of course, the contour line, span, and other information of cavity 1 can also be obtained through geological surveys. The degree of overburden fragmentation at the top of cavity 1 can also be evaluated, and then three-dimensional modeling of the corresponding area can be performed to obtain a three-dimensional geological model, so as to facilitate the subsequent arrangement of filling holes based on the location of cavity 1.

[0046] S102. Filling holes are arranged based on the position of cavity 1. The filling holes include multiple aggregate holes 21 and multiple cementing holes 22. Aggregate holes 21 are used to fill cavity 1 with a three-layer aggregate material. The three-layer aggregate material has tensile and compressive properties. Cementing holes 22 are used to fill cavity 1 with a cementing layer material. The cementing layer material has permeability and gelling properties, which can penetrate into the gaps between the three layers of aggregate material and the cracks in the rock formation surrounding cavity 1. After the filling is consolidated, the filling body is strengthened and connected to the surrounding rock formation.

[0047] Multiple aggregate holes 21 are spaced apart at locations within the cavity 1. The aggregate holes 21 can be arranged in a substantially rectangular array above the cavity 1. When the multiple aggregate holes 21 are sequentially filled with three layers of aggregate material, they can more evenly cover all areas of the cavity 1. The cementing holes 22 are located in the middle of the multiple aggregate holes 21 so that the multiple aggregate holes 21 are arranged circumferentially around the cementing holes 22, and each aggregate hole 21 is adjacent to at least one cementing hole 22. After the three layers of aggregate material are filled, the cementing material 4 is injected into the cavity 1 through the cementing holes 22. The cementing material 4 diffuses into the gaps within the aggregate holes 21 and mixes with the aggregate 3. As the cementing material 4 further diffuses, it can be evenly mixed with the aggregate 3 below the multiple circumferential aggregate holes 21, thereby improving the uniformity of the mixing of the aggregate 3 and the cementing material 4.

[0048] S103. Aggregate 3 and binder 4 are configured according to the required filling strength. Aggregate 3 includes coal gangue 31 and straw 32 in a preset ratio, and binder 4 includes loess and cement in a preset ratio. To simultaneously adapt the filling strength of the mining area cavity 1 and subsequent open-pit stripping mining, the embodiment of the present invention uses coal gangue 31 and straw 32 as aggregate 3 instead of the paste material used in the related art. The binder 4 and aggregate 3 are filled separately, which improves the filling effect and reduces the filling cost.

[0049] The paste material used in related art uses a mixture of gangue powder and cement. Gangue crushing consumes a lot of energy, and the paste material has poor fluidity and a small diffusion radius, making it difficult to fill small cracks. This results in unsatisfactory filling results and high filling costs. Compared to the solutions in related art, the coal gangue 31 in the aggregate 3 of the present embodiment has a lower crushing particle size requirement, which can reduce crushing energy consumption. The coal gangue 31 is mixed with straw 32, which can be used to increase the tensile strength of the gangue aggregate 3. The binder 4 uses loess, replacing more than 70% of the cement used in related art, reducing the overall cost by 45% to 60%. While the process cost of related art is 50 to 80 yuan per cubic meter, the process cost of the present embodiment can be reduced to 30 to 40 yuan per cubic meter. The binder 4 of the present embodiment has good fluidity, allowing it to mix better with the aggregate 3 and fill small cracks densely, thereby simultaneously achieving resource utilization of the gangue and straw 32. In the embodiment of the present invention, the filling body after filling and consolidation has stable structural strength and is adapted to the requirements of subsequent open-pit stripping mining operations, thereby improving subsequent operation efficiency.

[0050] S104: Aggregate 3 is delivered into the cavity 1 through the aggregate holes 21. Aggregate 3 is delivered into the cavity 1 sequentially through the aggregate holes 21. Aggregate 3 has a certain stacking angle. By properly controlling the spacing between adjacent aggregate holes 21, the delivery amount of aggregate 3 and the uniformity of the distribution of aggregate 3 on the horizontal plane can be guaranteed, thereby meeting the filling requirements.

[0051] S105. Inject cement 4 into cavity 1 through cement holes 22 until cement 4 flows out of adjacent aggregate holes 21. As cement 4 is injected into cavity 1 through cement holes 22, it mixes and blends with aggregate 3, achieving a mixture of cement 4 and aggregate 3. The cement 4 also enters the cracks in the rock formations surrounding cavity 1, thereby cementing the rock formations together. The cement 4 has good fluidity, and after mixing with aggregate 3, the consolidated filling structure is stable and has good compressive and tensile properties.

[0052] In step S104 and step S105, the aggregate 3 may be delivered first, and then the binder 4 may be injected. Alternatively, the aggregate 3 and the binder 4 may be injected alternately in multiple times to improve the uniformity of the mixing between the two.

[0053] The open-pit coal mine backfilling and remining method of the present invention uses loess and straw 32 to replace part of the backfill material, reducing backfill costs and realizing resource utilization of the gangue and straw 32. By arranging the backfill holes and distributing the aggregate 3 and binder 4, the density of the backfill in the tunnel cavity 1 can be improved, while the strength of the backfill can be controlled to meet the needs of subsequent open-pit stripping.

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

[0055] See also Figures 1 to 3 , a backfill mining method for open-pit coal mines, comprising:

[0056] S101. Obtain the location of cavity 1 in the goaf. Specifically, historical mining data is obtained. The situation of cavity 1 in the goaf can be determined based on historical mining drawings, written records, and other data. Then, ground-penetrating radar and drill holes are used to survey stratum 5 to obtain stratum 5 data. After processing this stratum 5 data, the boundaries and span of cavity 1 in the goaf, the relative heights of the roof and floor, and the development of fractures in the roof overburden can be determined. The location of coal pillar 6 can also be preliminarily determined. A three-dimensional geological model is constructed based on the historical mining data and stratum 5 data, and the location of cavity 1 is annotated.

[0057] The embodiment of the present invention obtains the contour line, span and other information of the cavity 1 after geological survey, evaluates the degree of overburden fragmentation at the top of the cavity 1, and then performs three-dimensional stereo 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 position of the cavity 1.

[0058] S102. Filling holes are arranged based on the position of cavity 1. The filling holes include multiple aggregate holes 21 and multiple cementing holes 22. Aggregate holes 21 are used to fill cavity 1 with a three-layer aggregate material. The three-layer aggregate material has tensile and compressive properties. Cementing holes 22 are used to fill cavity 1 with a cementing layer material. The cementing layer material has permeability and gelling properties, which can penetrate into the gaps between the three layers of aggregate material and the cracks in the rock formation surrounding cavity 1. After the filling is consolidated, the filling body is strengthened and connected to the surrounding rock formation.

[0059] Multiple aggregate holes 21 are spaced apart at locations within the cavity 1. The aggregate holes 21 can be arranged in a substantially rectangular array above the cavity 1. When the multiple aggregate holes 21 are sequentially filled with three layers of aggregate material, they can more evenly cover all areas of the cavity 1. The cementing holes 22 are located in the middle of the multiple aggregate holes 21 so that the multiple aggregate holes 21 are arranged circumferentially around the cementing holes 22, and each aggregate hole 21 is adjacent to at least one cementing hole 22. After the three layers of aggregate material are filled, the cementing material 4 is injected into the cavity 1 through the cementing holes 22. The cementing material 4 diffuses into the gaps within the aggregate holes 21 and mixes with the aggregate 3. As the cementing material 4 further diffuses, it can be evenly mixed with the aggregate 3 below the multiple circumferential aggregate holes 21, thereby improving the uniformity of the mixing of the aggregate 3 and the cementing material 4.

[0060] Specifically, the filling holes include a plurality of filling hole groups, each of which includes a plurality of aggregate holes 21 and a cementing hole 22, and adjacent filling hole groups share some aggregate holes 21;

[0061] The number of aggregate holes 21 ranges from 2 to 6, and multiple aggregate holes 21 are arranged circumferentially around the cementing holes 22. For example, if a partially filled hole group is arranged in a cavity 1 with a relatively small span, each filling hole group will have two aggregate holes 21 and one cementing hole 22, with the cementing hole 22 located between two aggregate holes 21. For another example, if a partially filled hole group is located in a cavity 1 with a relatively large span, each filling hole group will have 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 giving the filling hole group a plum blossom shape.

[0062] The diameter of the aggregate hole 21 of the embodiment of the present invention 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. When the diameters of the aggregate hole 21 and the cementing hole 22 are too large, the construction difficulty and construction amount are increased, affecting the construction progress. When the diameters of the aggregate hole 21 and the cementing hole 22 are too small, it is easy to cause the feed rate of the aggregate 3 or the cementing material 4 to be limited, which is not conducive to the rapid filling of the material.

[0063] In order to more reasonably arrange the filling holes above the cavity 1, the spacing between adjacent filling holes can be determined based on the span of the cavity 1. Specifically, the span of the cavity 1 is obtained, and it is determined whether the span of the 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 the 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, in this case, the distance between adjacent filling holes is 4.5m, 4.8m, 5m or 5.5m. When the span of the cavity 1 is greater than 5m, the spacing between adjacent filling holes is 6m to 8m. For example, in this case, the spacing between adjacent filling holes is 6m, 6.3m, 6.8m, 7.6m or 8m.

[0065] During the early geological survey, if broken overburden is found on the top of the cavity 1, the spacing between adjacent filling holes is increased to 3.5m to 4m. For example, the spacing between adjacent filling holes is 3.5m, 3.7m or 4m.

[0066] The embodiment of the present invention can improve the construction efficiency and filling efficiency while ensuring the stability of the filling body through the design of the filling hole spacing, and can better bond and mix the aggregate 3 and the binder 4, with good practicality.

[0067] S103. Aggregate 3 and binder 4 are configured according to the required filling strength. Aggregate 3 includes coal gangue 31 and straw 32 in a preset ratio, and binder 4 includes loess and cement in a preset ratio. To simultaneously adapt the filling strength of the mining area cavity 1 and subsequent open-pit stripping mining, the embodiment of the present invention uses coal gangue 31 and straw 32 as aggregate 3 instead of the paste material used in the related art. The binder 4 and aggregate 3 are filled separately, which improves the filling effect and reduces the filling cost.

[0068] The particle size of the gangue 31 in the embodiment of the present invention is 80 mm or less. Compared to the related art method of grinding the gangue 31 into particles 10 mm or less, the embodiment of the present invention can reduce energy consumption costs for gangue 31 processing by over 40%. The straw 32 is 5 to 10 cm long and can be crushed by a pulverizer. The straw 32 in the aggregate 3 accounts for 2.5 to 3.5% of the mass of the gangue 31. The mixture is mixed evenly during use and then placed into the cavity 1.

[0069] Binder 4 comprises the following raw materials by weight: 80 to 90 parts loess, 10 to 20 parts cement, and an appropriate amount of water. The loess in binder 4 has a particle size of 2 mm or less. After crushing and screening, loess with a particle size of less than 2 mm is selected and mixed with cement, followed by addition of water and stirring. The water-cement ratio of binder 4 is 0.7 to 0.8. For example, binder 4 may comprise 85 parts loess and 15 parts cement. PO 42.5 cement can be used.

[0070] The viscosity of the binder 4 prepared after mixing and stirring was tested using a Marsh funnel, and the parameter value met the range of 35s to 40s, ensuring that it had good fluidity and bonding properties.

[0071] The paste material used in related art uses a mixture of gangue powder and cement. Gangue crushing consumes a lot of energy, and the paste material has poor fluidity and a small diffusion radius, making it difficult to fill small cracks. This results in unsatisfactory filling results and high filling costs. Compared to the solutions in related art, the coal gangue 31 in the aggregate 3 of the present embodiment has a lower crushing particle size requirement, which can reduce crushing energy consumption. The coal gangue 31 is mixed with straw 32, which can be used to increase the tensile strength of the gangue aggregate 3. The binder 4 uses loess, replacing more than 70% of the cement used in related art, reducing the overall cost by 45% to 60%. While the process cost of related art is 50 to 80 yuan per cubic meter, the process cost of the present embodiment can be reduced to 30 to 40 yuan per cubic meter. The binder 4 of the present embodiment has good fluidity, allowing it to mix better with the aggregate 3 and fill small cracks densely, thereby simultaneously achieving resource utilization of the gangue and straw 32. In the embodiment of the present invention, the filling body after filling and consolidation has stable structural strength and is adapted to the requirements of subsequent open-pit stripping mining operations, thereby improving subsequent operation efficiency.

[0072] S104: Aggregate 3 is delivered into the cavity 1 through the aggregate holes 21. Aggregate 3 is delivered into the cavity 1 sequentially through the aggregate holes 21. Aggregate 3 has a certain stacking angle. By properly controlling the spacing between adjacent aggregate holes 21, the delivery amount of aggregate 3 and the uniformity of the distribution of aggregate 3 on the horizontal plane can be guaranteed, thereby meeting the filling requirements.

[0073] S105. Inject cement 4 into cavity 1 through cement holes 22 at a pressure of 0.3 MPa to 0.5 MPa until cement 4 flows out of adjacent aggregate holes 21. As cement 4 is injected into cavity 1 through cement holes 22, it mixes and blends with aggregate 3, achieving a mixture of cement 4 and aggregate 3. The cement 4 also enters the cracks in the rock formations surrounding cavity 1, thereby cementing the rock formations together. The cement 4 has good fluidity, and after mixing with aggregate 3, the consolidated filling structure is stable and has good compressive and tensile properties.

[0074] In step S104 and step S105, the aggregate 3 may be delivered first, and then the binder 4 may be injected. Alternatively, the aggregate 3 and the binder 4 may be injected alternately in multiple times to improve the uniformity of the mixing between the two.

[0075] After the grouting of aggregate 3 and binder 4 is completed, it is left to stand for 7 days for curing. At this time, the filling body is solidified and the uniaxial compressive strength reaches more than 1MPa, and then re-mining operations are allowed.

[0076] The open-pit coal mine backfilling and remining method of the present invention uses loess and straw to replace some of the backfill materials, reducing backfill costs and realizing resource utilization of waste rock and straw. By arranging the filling holes and distributing the aggregate and binder, the density of the filling in the tunnel cavity can be improved, while the filling strength can be controlled to meet the needs of subsequent open-pit stripping.

[0077] Compared with the filling density of 75-85% in the related art, the filling density of the embodiment of the present invention is 92-95%, which can prevent the accumulation of water and gas in the goaf and is safer.

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

[0079] The comprehensive cost is significantly reduced in the embodiment of the present invention. By reducing the energy consumption of gangue crushing and replacing cement / fly ash with loess in the open air, the filling cost is reduced to 30 yuan / m 3 ~40 yuan / m 3 , the cost is reduced by nearly 50%.

[0080] The present invention also offers additional benefits: each cubic meter of filling volume can absorb 1.8 tons of coal gangue and 0.05 tons of straw. The ground settlement after filling is less than 3 cm / year, meeting the requirements for safe passage of open-pit mining equipment.

[0081] In the description of the present invention, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", "clockwise", "counterclockwise", "axial", "radial", "circumferential" and the like to indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as limiting the present 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 the technical features being referred to. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one such feature. In the description of the present invention, "plurality" means at least two, such as two, three, etc., unless otherwise specifically defined.

[0083] In the present invention, unless otherwise specified or limited, the terms "installed," "connected," "connect," "fixed," etc. should be understood in a broad sense. For example, they can refer to fixed connection, detachable connection, or integration; mechanical connection, electrical connection, or communication; direct connection or indirect connection through an intermediate medium; internal communication between two elements or interaction between two elements, unless otherwise specified. Those skilled in the art will understand the specific meanings of the above terms in the present invention based on specific circumstances.

[0084] In the present invention, unless otherwise expressly specified or limited, when a first feature is "above" or "below" a second feature, it may mean that the first and second features are in direct contact, or that the first and second features are in indirect contact through an intermediary. Furthermore, when a first feature is "above," "above," or "above" a second feature, it may mean that the first feature is directly above or diagonally above the second feature, or simply means that the first feature is at a higher level than the second feature. When a first feature is "below," "below," or "below" a second feature, it may mean that the first feature is directly below or diagonally below the second feature, or simply means that the first feature is at a lower level than the second feature.

[0085] In the present invention, the terms "one embodiment", "some embodiments", "examples", "specific examples", or "some examples" mean that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic expressions of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described can be combined in any one or more embodiments or examples in a suitable manner. In addition, those skilled in the art can combine and combine different embodiments or examples described in this specification and the features of different embodiments or examples without contradiction.

[0086] Although the embodiments of the present invention have been shown and described above, it will be understood that the above embodiments are illustrative and are not to be construed as limitations on the present invention. A person skilled in the art may change, modify, replace and modify the above embodiments within the scope of the present invention.

Claims

1. A backfill mining method for open-pit coal mines, characterized in that: include: Get the cavity position of the goaf; Arranging filling holes based on the cavity position, the filling holes including a plurality of aggregate holes and a plurality of cementing holes, the plurality of aggregate holes being distributed at intervals at the cavity position, the cementing holes being located in the middle of the plurality of aggregate holes so that the plurality of aggregate holes are arranged around the circumference of the cementing holes, and each of the aggregate holes is disposed adjacent to at least one of the cementing holes; Aggregates and binders are configured according to filling strength requirements, wherein the aggregates include coal gangue and straw in a preset ratio, and the binders include loess and cement in a preset ratio; delivering aggregate into the cavity through the aggregate holes; The cementing material is injected into the cavity through the cementing holes until the cementing material flows out from the adjacent aggregate holes.

2. The open-pit coal mine backfilling and re-mining method according to claim 1, characterized in that: The filling holes include a plurality of filling hole groups, each of the filling hole groups includes a plurality of aggregate holes and a cementing hole, and adjacent filling hole groups share some of the aggregate holes; In one group of the filling holes, the number of the aggregate holes is 2 to 6, and the plurality of aggregate holes are arranged around the circumference of the cementing hole.

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

4. The open-pit coal mine backfilling and re-mining method according to any one of claims 1 to 3, characterized in that: The step of arranging the filling holes based on the cavity position comprises: Obtaining the span of the cavity, and determining 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 distance between adjacent filling holes is 6m to 8m.

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

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

7. The open-pit coal mine backfilling and re-mining method according to claim 1, characterized in that: The particle size of the coal gangue is less than or equal to 80 mm, the length of the straw is 5 cm to 10 cm, and the straw content in the aggregate accounts for 2.5% to 3.5% of the mass of the coal gangue.

8. The open-pit coal mine backfilling and re-mining method according to claim 1, characterized in that: The viscosity of the binder satisfies the Marsh funnel viscosity of 35s to 40s.

9. The open-pit coal mine backfilling and re-mining method according to claim 8, characterized in that: The binder comprises the following raw materials in parts by weight: 80 to 90 parts of loess, 10 to 20 parts of cement, and an appropriate amount of water. The loess particle size in the binder is less than or equal to 2 mm, and the water-cement ratio of the binder is 0.7 to 0.

8. And / or, the step is to inject the binder into the cavity through the binder hole, and inject the binder into the cavity through the binder hole at a pressure of 0.3 MPa to 0.5 MPa.

10. The open-pit coal mine backfilling and re-mining method according to claim 1, characterized in that: The steps for obtaining the cavity position of the goaf include: Obtain historical mining data; Use ground penetrating radar and drill holes to conduct stratigraphic surveys and obtain stratigraphic data; A three-dimensional geological model is constructed based on the historical mining data and the stratigraphic data, and the cavity locations are marked.

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