Caving and filling mining method

Abstract

The present application relates to a kind of caving filling mining method, comprising the following steps: step A: the position of surface caving area and the size of the subsidence area formed after the subsidence of the surface caving area are obtained, the volume V1 of the subsidence area is calculated;Step B: preparation filling body;Step C: the filling body is stored to the position of the surface caving area, so that the filling body fills the subsidence area when the surface caving area subsidence forms the subsidence area, the volume of the filling body stored is V2, the difference between V1 and V2 is less than or equal to preset value.The caving filling mining method of the present application compared with the way of filling after the formation of subsidence area in related art has certain foresight, not only can fill as subsidence, improves mining safety and mining efficiency.

Description

Technical Field

[0001] This invention relates to the field of mining technology, and in particular to a caving backfill mining method. Background Technology

[0002] Caving mining is a mining method where, during the mining process, no stopes or pillars are separated. As the mining face advances, the surrounding rock, either forced or naturally caving, fills the goaf to manage ground pressure. Caving mining creates caving zones on the surface, which collapse to form subsidence areas (also known as subsidence pits). These subsidence areas must be filled. In related technologies, waste rock is used to fill these subsidence areas after they form. However, this filling is done after the subsidence area has formed, which is a delayed process. During the formation of the subsidence area, it often develops and expands, potentially triggering secondary disasters. Summary of the Invention

[0003] This invention aims to at least partially solve some of the technical problems in related technologies. To this end, embodiments of this invention propose a caving-filling mining method, which has a certain degree of forward-looking capability, allowing for on-site filling as the caving occurs, thus improving mining safety and efficiency.

[0004] The caving backfilling mining method of this invention includes the following steps:

[0005] Step A: Obtain the location of the subsidence area and the size of the subsidence area formed after the collapse of the surface landslide area, and calculate the volume V1 of the subsidence pit;

[0006] Step B: Preparation of the filling material;

[0007] Step C: The filling material is piled up at the location of the surface collapse area so that when the surface collapse area collapses to form the collapse area, the filling material fills the collapse area. The volume of the piled filling material is V2, and the difference between V1 and V2 is less than or equal to a preset value.

[0008] Compared with the method of filling the collapse zone after its formation in related technologies, the caving filling mining method of this invention has a certain degree of foresight. It can not only fill the collapse zone as it collapses, but also improve mining safety and mining efficiency.

[0009] In some embodiments, the filling material includes a bagged filling material, and the method for preparing the bagged filling material includes the following steps:

[0010] Step b1: Filter the tailings waste to obtain tailings and filter water;

[0011] Step b2: The tailings are bagged to obtain the bagged filler.

[0012] In some embodiments, the filling material includes a block-shaped filling material, and the method for preparing the block-shaped filling material includes the following steps:

[0013] Step b3: Filter the tailings waste to obtain tailings and filter water;

[0014] Step b4: Prepare a first slurry, the first slurry comprising a first cementing material, the tailings and the filtered water, wherein the mass ratio of the first cementing material to the tailings is 1:(4-20), and the mass percentage of the sum of the first cementing material and the tailings to the first slurry is 60%-75%.

[0015] Step b5: Pressing and molding, pressing the first slurry into a block shape to obtain the block filling body.

[0016] In some embodiments, the filling material includes a granular filling material, and the method for preparing the granular filling material includes the following steps:

[0017] Step b6: Filter the tailings waste to obtain tailings and filter water;

[0018] Step b7: Prepare a first slurry, the first slurry comprising a first cementing material, the tailings and the filtered water, wherein the mass ratio of the first cementing material to the tailings is 1:(4-20), and the mass percentage of the sum of the first cementing material and the tailings to the first slurry is 60%-75%.

[0019] Step b8: Pressing and molding, pressing the first slurry into granules to obtain the granular filler.

[0020] In some embodiments, the first cementing material comprises steel slag, blast furnace slag, and desulfurized gypsum, wherein the mass percentage of steel slag is 30%-50%, the mass percentage of blast furnace slag is 30%-40%, and the mass percentage of desulfurized gypsum is 10%-30%.

[0021] In some embodiments, the caving and backfilling mining method further includes step D: after step C, when the surface caving zone collapses and the backfill material fills the collapsed zone, a second slurry is used to fill the gaps in the collapsed zone.

[0022] In some embodiments, the second slurry comprises a second cementing material, tailings, and water, wherein the mass ratio of the second cementing material to the tailings is 1:(4-20), and the sum of the second cementing material and the tailings constitutes 60%-75% of the mass of the second slurry.

[0023] In some embodiments, the second cementing material is prepared from steel slag, blast furnace slag and desulfurized gypsum, wherein the mass percentage of steel slag is 30%-50%, the mass percentage of blast furnace slag is 30%-40%, and the mass percentage of desulfurized gypsum is 10%-30%.

[0024] In some embodiments, the filling material includes a granular filling material. In step D, before filling the gaps in the collapsed area with grout, the collapsed area is filled with the granular filling material to level the collapsed pit.

[0025] In some embodiments, in step A, the location of the surface landslide area and the size of the subsidence area are obtained, and the major semi-axis a, minor semi-axis b, and depth c of the subsidence area are obtained. The volume calculation formula for the subsidence area is: In the formula, the unit of each of a, b and c is m. Attached Figure Description

[0026] Figure 1 This is a schematic diagram illustrating the implementation of the caving and backfilling mining method according to an embodiment of the present invention. Detailed Implementation

[0027] 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.

[0028] like Figure 1 As shown, the caving backfill mining method of this invention includes the following steps:

[0029] Step A: Obtain the location of the surface collapse area and the size of the subsidence area formed after the surface collapse area collapses, and calculate the volume V1 of the subsidence area;

[0030] Step B: Preparation of the filling material;

[0031] Step C: The filling material is piled up at the location of the surface collapse area so that when the surface collapse area collapses and forms a collapse area, the filling material fills the collapse area. The volume of the piled filling material is V2, and the difference between V1 and V2 is less than or equal to a preset value.

[0032] The caving and backfilling mining method of this invention first determines the location of the surface caving zone, then piles a backfill material with a volume equivalent to the caving zone at that location. Thus, during the collapse of the surface caving zone—that is, during the formation of the caving zone—as the surface of the caving zone subsides, the backfill material sinks and immediately fills the caving zone. This achieves simultaneous filling and subsidence of the surface caving zone, forming a stable overburden layer within the caving zone. This effectively prevents further development and expansion of the caving zone during its formation, avoids secondary disasters, and meets the needs of safe mine production. Furthermore, the backfill material has a certain weight; its presence at the location of the surface caving zone increases the pressure in that area, accelerating the roof collapse rate during ore caving and improving mining efficiency.

[0033] Therefore, the caving backfilling mining method of the present invention has a certain degree of foresight compared with the method of backfilling after the formation of the caving area in related technologies. It can not only fill as the caving occurs, thus improving mining safety, but also improve mining efficiency.

[0034] In some embodiments, in step A, based on the geological conditions of the mine, the location and size of the surface collapse zone are obtained through engineering analogy and / or numerical simulation methods, resulting in the semi-major axis a, semi-minor axis b, and depth c of the collapse zone. The volume calculation formula for the collapse zone is: In the formula, the unit of each of a, b and c is m. The volume V1 of the collapse zone is calculated according to this formula.

[0035] Mineral geological conditions include the geological strata of the mine, fault distribution, physical and mechanical parameters of the ore and rock, and the occurrence conditions of the ore body.

[0036] The engineering analogy method refers to the location and size of the surface collapse area formed by the caving mining method under the same geological conditions of the mine, and obtains the major semi-axis a, minor semi-axis b and depth c of the collapse area.

[0037] The numerical simulation method uses FLAC3D software to perform numerical simulations, and inputs the physical and mechanical parameters of the ore and rock to obtain a, b, and c.

[0038] When using both the engineering analogy method and the numerical simulation method, the values ​​of a, b, and c obtained from the two methods are compared, and the larger value is used for calculation. For example, if the engineering analogy method yields the major semi-axis of the collapse zone as a1, the minor semi-axis as b1, and the depth as c1, and the numerical simulation method yields the major semi-axis as a2, the minor semi-axis as b2, and the depth as c2, then when calculating the volume V1 of the collapse zone, a is the larger of a1 and a2, b is the larger of b1 and b2, and c is the larger of c1 and c2.

[0039] The filling material includes at least one of bagged filling material, block filling material, and granular filling material. Therefore, the filling material stored in the surface subsidence area is either bagged filling material, block filling material, granular filling material, bagged filling material and block filling material, bagged filling material and granular filling material, block filling material and granular filling material, or bagged filling material, block filling material and granular filling material.

[0040] The different shapes and sizes of bagged filling materials, block filling materials, and granular filling materials allow the caving filling mining method of this invention to be flexibly selected or combined in different situations of different sizes of subsidence areas and surface caving areas, thereby improving the adaptability and applicability of the caving filling mining method.

[0041] The preparation method of bagged filler includes the following steps:

[0042] Step b1: Filter the tailings waste to obtain tailings and filter water;

[0043] Step b2: Bag the tailings to obtain bagged filling material.

[0044] The bagged filling material is prepared using tailings waste. The preparation method is simple, low-cost, and easy to store and transport. It can effectively utilize tailings waste and solve the problems of land occupation, environmental pollution, and safety hazards caused by the need for tailings ponds to store tailings waste in related technologies. It reduces the space and cost occupied by tailings waste treatment in related technologies and reduces the environmental pollution caused by the large-scale stockpiling of tailings waste.

[0045] The method for preparing block-shaped fillers includes the following steps:

[0046] Step b3: Filter the tailings waste to obtain tailings and filter water;

[0047] Step b4: Prepare the first slurry, which includes a first cementing material, tailings and filter water. The mass ratio of the first cementing material to the tailings is 1:(4-20). The total mass of the first cementing material and the tailings is 60%-75% of the mass of the first slurry.

[0048] Step b5: Pressing and molding, pressing the first slurry into blocks to obtain block-shaped fillers.

[0049] Block backfill containing primary cementing material and tailings exhibits high strength and good stability, which is beneficial for the stability of the overburden layer formed by the backfill in the subsidence pit area, ensuring the filling effect of the subsidence area. Furthermore, block backfill can effectively utilize tailings waste, solving the problems of land occupation, environmental pollution, and safety hazards caused by the need for tailings ponds in mineral processing plants to store tailings waste in related technologies. It reduces the space and cost required for tailings waste treatment in related technologies and minimizes environmental pollution caused by large-scale tailings waste storage.

[0050] In some embodiments, the block infill material obtained in step b5 is packaged using a block packaging machine to facilitate its transportation and storage. The block infill material is then transported to the landslide area for storage using a flatbed truck.

[0051] The preparation method of granular filling materials includes the following steps:

[0052] Step b6: Filter the tailings waste to obtain tailings and filter water;

[0053] Step b7: Prepare the first slurry, which includes the first cementing material, tailings and filter water. The mass ratio of the first cementing material to the tailings is 1:(4-20), and the sum of the first cementing material and the tailings accounts for 60%-75% of the mass of the first slurry.

[0054] Step b8: Pressing and molding, pressing the first slurry into granules to obtain granular filler.

[0055] Granular backfill containing primary cementing material and tailings exhibits high strength and good stability, facilitating the formation of a stable overburden layer within the subsidence area and ensuring effective filling. Furthermore, granular backfill effectively utilizes tailings waste, resolving the land occupation, environmental pollution, and safety hazards associated with tailings ponds used in mineral processing plants in related technologies. This reduces the space and cost required for tailings waste treatment in these technologies and minimizes environmental pollution caused by large-scale tailings stockpiling.

[0056] In addition, granular filling materials are smaller in volume than block filling materials and bagged filling materials, resulting in a smaller porosity of the capping layer formed by the filling material in the collapse zone, which can further improve the stability of the capping layer and the filling effect on the collapse zone.

[0057] In some embodiments, the granular infill material obtained in step b8 is packaged using a granule packaging machine to facilitate its transportation and storage. The granular infill material is then transported by conveyor belt to a location in the landslide area for storage.

[0058] At least one of the bagged filling body, block filling body and granular filling body prepared by the caving filling mining method of the present invention can also be used for open pit filling treatment, ecological restoration and other aspects. It not only has high filling efficiency, but is also less affected by environmental factors.

[0059] In some embodiments, the first cementing material comprises steel slag, blast furnace slag, and desulfurized gypsum, wherein the mass percentage of steel slag is 30%-50%, the mass percentage of blast furnace slag is 30%-40%, and the mass percentage of desulfurized gypsum is 10%-30%. That is, the percentage ratio of the mass of steel slag to the mass of the first cementing material is 30%-50%, the percentage ratio of the mass of blast furnace slag to the mass of the first cementing material is 30%-40%, and the percentage ratio of the mass of desulfurized gypsum to the mass of the first cementing material is 10%-30%.

[0060] Steel slag is a waste residue produced in the metallurgical industry, while ore slag is a by-product of the blast furnace ironmaking process. Steel slag has a low cost, which reduces the cost of the first cementing material by about 50% compared to traditional cement and by about 20% compared to ore slag cementing materials. This further reduces the cost of block and granular backfill materials, thereby reducing the cost of the caving backfill mining method of the present invention.

[0061] Optionally, in the first cementitious material, the mass percentage of steel slag is 40%, the mass percentage of blast furnace slag is 35%, and the mass percentage of desulfurized gypsum is 25%.

[0062] In some embodiments, the caving backfill mining method further includes step D: after step C, when the surface caving area collapses and the backfill material fills the collapsed area, granular backfill material is used to supplement and fill the collapsed area to level it. A second slurry is then used to fill the gaps in the collapsed area. The second slurry includes a second cementitious material, tailings, and water. The mass ratio of the second cementitious material to the tailings is 1:(4-20), and the sum of the second cementitious material and tailings accounts for 60%-75% of the mass of the second slurry. The tailings used in the second slurry are tailings obtained after tailings waste is filtered, and the water is filter water obtained after tailings waste is filtered. Optionally, the tailings and filter water used in the second slurry can be tailings and filter water obtained in any of steps b1, b3, and b6.

[0063] The granular backfill material has a small volume, which can further fill the subsidence area, replenish the unfilled part of the overburden, level the subsidence area, and reduce the porosity of the overburden, thereby further improving the filling effect of the subsidence area, further improving the stability of the overburden, and thus further improving mining safety.

[0064] After leveling the subsidence area, a second grout is used to fill the gaps. This fills and reinforces the gaps between adjacent filling bodies within the subsidence area, the gaps between the filling bodies and the subsidence area, and the gaps on the walls of the subsidence area. This not only further reduces the porosity of the filling bodies within the subsidence area, but also integrates the filling bodies with the surrounding rock of the subsidence area, consolidating the filling effect of the filling bodies on the subsidence area, thereby further improving mining safety.

[0065] The second slurry, consisting of tailings and filter water, is not only low in cost but also further consumes tailings waste, further reducing the space and cost required for tailings waste treatment in related technologies.

[0066] In some embodiments, the second cementing material is prepared from steel slag, blast furnace slag and desulfurized gypsum, wherein the mass percentage of steel slag is 30%-50%, the mass percentage of blast furnace slag is 30%-40%, and the mass percentage of desulfurized gypsum is 10%-30%.

[0067] The cost of the second cementitious material is reduced by about 50% compared to traditional cement and by about 20% compared to slag cementitious materials, thereby further reducing the cost of the caving backfill mining method of this embodiment of the invention.

[0068] Optionally, in the second cementing material, the mass percentage of steel slag is 46%, the mass percentage of blast furnace slag is 32%, and the mass percentage of desulfurized gypsum is 22%.

[0069] Optionally, if the second slurry is the same as the first slurry, then when implementing the caving backfill mining method of the present invention, using the first slurry to fill the gaps in the collapsed area can further simplify the steps of the caving backfill mining method of the present invention.

[0070] The following describes specific embodiments of the caving backfill mining method of the present invention.

[0071] Example 1:

[0072] The caving backfilling mining method of this invention includes the following steps:

[0073] Step A: Obtain the geological conditions of the mine. The physical and mechanical parameters of the ore and rock are shown in Table 1. Numerical simulation using FLAC3D software is used to obtain the location and size of the surface collapse zone, yielding a = 36.6m, b = 19.8m, and c = 9.9m. Based on the volume calculation formula for the collapse zone, V1 = 1.5 * 10⁻⁶ m. 4 m3.

[0074] Table 1 Physical and mechanical parameters of ore and rock

[0075]

[0076] Step B: Prepare bagged filler.

[0077] Step b1: Filter the tailings waste to obtain tailings and filter water;

[0078] Step b2: Use a bagging machine to fill the tailings into woven bags, and use a sealing machine to seal them to obtain bagged filler.

[0079] Step C: The bagged filler is transported to the landslide area using a belt conveyor for storage. The volume of the stored bagged filler is V2 = V1 = 1.5 * 10. 4 m3.

[0080] As the surface collapse zone subsides, the bagged infill material sinks and then fills the collapse zone.

[0081] Step D: After the surface collapse zone is filled with bagged infill material, the surface is stabilized and the collapse zone is leveled, so that the filling rate of the collapse zone reaches 94%.

[0082] The second cementitious material is prepared with a mass percentage of 50% steel slag, 35% blast furnace slag, and 15% desulfurized gypsum. The second slurry is prepared with a mass ratio of 1:4 between the second cementitious material and the tailings obtained in step b1, and a mass percentage of 70% of the sum of the second cementitious material and the tailings to the second slurry. The filter water used in the second slurry is the filter water obtained in step b1.

[0083] Then, a second grout is used to fill the gaps in the leveled collapsed area. Once the second grout has solidified, the filling is complete.

[0084] Example 2

[0085] The caving backfilling mining method of this invention includes the following steps:

[0086] Step A: Obtain the geological conditions of the mine. The physical and mechanical parameters of the ore and rock are shown in Table 2. Numerical simulation using FLAC3D software is used to obtain the location and size of the surface collapse zone, yielding a = 34.7m, b = 20.4m, and c = 8.1m. Based on the volume calculation formula for the collapse zone, V1 = 1.2 * 10⁻⁶ m. 4 m3.

[0087] Table 2 Physical and mechanical parameters of ore and rock

[0088]

[0089] Step B: Prepare block-shaped and granular filling materials.

[0090] Step b3: Filter the tailings waste to obtain tailings and filter water;

[0091] Step b4: Prepare the first cementitious material with a mass percentage of 50% steel slag, 40% blast furnace slag, and 10% desulfurized gypsum. Prepare the first slurry with a mass ratio of 1:8 between the first cementitious material and tailings, and with the sum of the first cementitious material and tailings accounting for 75% of the mass percentage of the first slurry. The filter water used for the first slurry is the filter water obtained in step b3.

[0092] Step b5: Press the first slurry into blocks using a block molding machine to obtain a block filling body.

[0093] Step b8: Press the first slurry into granules using a granulation molding machine to obtain granular filler.

[0094] Step C: The block backfill material is transported to the surface collapse area using a flatbed truck for storage. The volume of the stored block backfill material is V2 = 1.1 * 10⁻⁶. 4 m3.

[0095] As the surface collapse zone subsides, the blocky infill material sinks and then fills the collapse zone.

[0096] Step D: After the surface collapse and block-shaped backfill material fills the collapsed area, the surface is stable. A pelletizing machine is used to throw granular backfill material into the collapsed area to supplement the unfilled portions and level the collapsed area. The first slurry prepared in step b4 is used to fill the gaps in the collapsed area. After the first slurry solidifies, the filling is complete.

[0097] 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.

[0098] 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.

[0099] 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.

[0100] 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.

[0101] 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.

[0102] 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 caving and backfilling mining method, characterized in that, Includes the following steps: Step A: Before the subsidence area forms, obtain the location of the surface collapse area and the size of the subsidence area formed after the surface collapse area collapses, and calculate the volume of the subsidence area. V 1; Step B: Prepare the filling material, wherein the filling material includes at least one of bagged filling material, block filling material and granular filling material; Step C: Before the collapse zone forms, the infill material is piled up at the location of the surface landslide area so that when the surface landslide area collapses to form the collapse zone, the infill material fills the collapse zone. Placing the infill material at the location of the surface landslide area increases the pressure in that area, thereby accelerating the collapse speed of the top slab of the collapse zone. The volume of the piled-up infill material is... V 2, V 1 and V The difference between 2 and 3 is less than or equal to the preset value.

2. The caving and backfilling mining method according to claim 1, characterized in that, The method for preparing the bagged filler includes the following steps: Step b1: Filter the tailings waste to obtain tailings and filter water; Step b2: The tailings are bagged to obtain the bagged filler.

3. The caving and backfilling mining method according to claim 1, characterized in that, The method for preparing the block-shaped filler includes the following steps: Step b3: Filter the tailings waste to obtain tailings and filter water; Step b4: Prepare a first slurry, the first slurry comprising a first cementing material, the tailings and the filtered water, wherein the mass ratio of the first cementing material to the tailings is 1:(4-20), and the mass percentage of the sum of the first cementing material and the tailings to the first slurry is 60%-75%. Step b5: Pressing and molding, pressing the first slurry into a block shape to obtain the block filling body.

4. The caving and backfilling mining method according to claim 1, characterized in that, The method for preparing the granular filling material includes the following steps: Step b6: Filter the tailings waste to obtain tailings and filter water; Step b7: Prepare a first slurry, the first slurry comprising a first cementing material, the tailings and the filtered water, wherein the mass ratio of the first cementing material to the tailings is 1:(4-20), and the mass percentage of the sum of the first cementing material and the tailings to the first slurry is 60%-75%; Step b8: Pressing and molding, pressing the first slurry into granules to obtain the granular filler.

5. The caving and backfilling mining method according to any one of claims 3 or 4, characterized in that, The first cementitious material includes steel slag, blast furnace slag and desulfurized gypsum, with steel slag accounting for 30%-50% of the mass, blast furnace slag accounting for 30%-40% of the mass, and desulfurized gypsum accounting for 10%-30% of the mass.

6. The caving and backfilling mining method according to claim 4, characterized in that, The process further includes step D: after step C, when the surface collapse zone has collapsed and the filling material has filled the collapsed zone, a second slurry is used to fill the gaps in the collapsed zone.

7. The caving and backfilling mining method according to claim 6, characterized in that, The second slurry includes a second cementing material, the tailings, and the filter water. The mass ratio of the second cementing material to the tailings is 1:(4-20), and the total mass percentage of the second cementing material and the tailings to the second slurry is 60%-75%.

8. The caving and backfilling mining method according to claim 7, characterized in that, The second cementitious material is prepared from steel slag, blast furnace slag and desulfurized gypsum, with the steel slag accounting for 30%-50% by mass, the blast furnace slag accounting for 30%-40% by mass, and the desulfurized gypsum accounting for 10%-30% by mass.

9. The caving and backfilling mining method according to claim 6, characterized in that, In step D, before filling the gaps in the collapsed area with grout, the collapsed area is filled with the granular filler to level it.

10. The caving and backfilling mining method according to claim 1, characterized in that, In step A, the location of the landslide area and the size of the subsidence area are obtained, and the semi-major axis of the subsidence area is obtained. a short half shaft b and the depth of the collapsed area c The formula for calculating the volume of the collapsed area is: In the formula a , b and c The unit for each of these is m.

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