Coal-based solid waste caving area fluidized filling treatment and loss reduction cooperated mining method

Abstract

The invention belongs to the technical field of green mining of coal mines, and discloses a coal-based solid waste caving area fluidization filling treatment collaborative loss reduction mining method, which comprises the following steps of: screening a filling space with a proper size by matching a positive equilibrium relationship between the volume of a coal-based solid waste pre-prepared filling material and a filling space of a caving area; secondly, the filling operation is divided into a plurality of filling window periods according to the positions of the working face and the arch feet of the semi-arch structure; and finally, filling of each window period is completed in sequence in a retreating type fluidization filling mode. By adopting the method, the solid waste source treatment efficiency is improved, the material preparation cost is reduced, the space resource utilization rate of the caving area is optimized, and the synergism of waste storage and loss reduction mining is enhanced, so that the problem of ecological environment damage caused by ground solid waste stockpiling and underground goaf is effectively relieved.

Description

Technical Field

[0001] The invention belongs to the technical field of green coal mining, and particularly relates to a method for collaborative loss reduction mining by fluidized filling disposal in the caving area of coal-based solid waste. Background Art

[0002] In the field of coal resource development and utilization, problems such as a large amount of solid waste piled up on the ground and the formation of large underground goafs have severely aggravated the damage to the mining area ecological environment. Currently, the contradiction between the demand for coal-based solid waste disposal and the bearing capacity of the ground ecological environment is becoming increasingly sharp, and the marginal benefit of obtaining space resources from surface stacking is continuously decreasing; at the same time, the strata movement caused by coal mining leads to a series of safety and environmental problems, and the continuously deforming damage of the non-compacted space formed after the natural collapse of the roof in the caving area poses a great threat to the safety production in the mining area and the protection of the surface ecology.

[0003] Currently, green mining and the construction of waste-free mines have become an inevitable trend in the industry's development. Green and efficient disposal of coal-based solid waste and reduction of mining damage are common problems faced by coal enterprises. The fluidized filling technology in the caving area of coal-based solid waste has become an important solid waste disposal and loss reduction mining technology, but there are many problems in actual application. After the underground coal seam is mined out, the dynamic compaction in the caving area and the continuous change of the void structure affect the safety and stability of the mine filling system, resulting in low source disposal efficiency of coal-based solid waste, high preparation cost of solid waste filling materials, insufficient utilization of the space resources in the caving area, and poor coordination between waste storage and loss reduction.

[0004] In summary, the existing technology cannot achieve collaborative loss reduction mining with green and efficient disposal of coal-based solid waste at the source, and it is difficult to effectively solve the problems of a large amount of solid waste piled up on the ground and the formation of large underground goafs aggravating the damage to the mining area ecological environment. Summary of the Invention

[0005] The invention provides a method for collaborative loss reduction mining by fluidized filling disposal in the caving area of coal-based solid waste. By using this method, collaborative loss reduction mining with green and efficient disposal of coal-based solid waste at the source is achieved, and the problems of a large amount of solid waste piled up on the ground and the formation of large underground goafs aggravating the damage to the mining area ecological environment are effectively solved.

[0006] In order to achieve the above object, the invention adopts the following technical scheme: A method for collaborative loss reduction mining by fluidized filling disposal in the caving area of coal-based solid waste, comprising: Based on the positive equilibrium relationship between the volume of the filling material and the filling space in the caving area, the volume of the filling material is matched with the filling space in the caving area to screen out the filling space in the caving area that meets the conditions; the filling material is pre-prepared based on the coal-based solid waste to be filled and disposed in the mine and its surrounding areas; the filling space in the caving area is calculated based on the coal seam extraction volume, the surface subsidence volume, and the unloading expansion volume of the fracture zone and the bending subsidence zone; Based on the positions of the working face of the caving area filling space and the arch feet of the semi-arch structure obtained by screening, the filling operation of the caving area filling space is divided into multiple filling windows; According to the sequence of the filling windows, the backstepping fluidized filling method is used to carry out the filling operations for each filling window in turn until the filling operation corresponding to the last filling window is completed.

[0007] Furthermore, based on the positive equilibrium relationship between the volume of the filling material and the caving area filling space, matching the volume of the filling material with the caving area filling space includes: According to the positive equilibrium relationship between the volume of the filling material and the caving area filling space, matching the volume of the filling material with the caving area filling space; The specific expression of the positive equilibrium relationship is as follows:

[0008] In the formula, V c represents the caving area filling space; V f represents the volume of the filling material; The calculation formula for the caving area filling space is as follows:

[0009] In the formula, V 1 represents the volume of coal seam mined out; V 2 represents the volume of surface subsidence; V 3 represents the unloading and swelling volume of the fracture zone and the bending subsidence zone; k represents the space utilization coefficient of the caving area, and the space utilization coefficient of the caving area is obtained through filling tests.

[0010] Furthermore, based on the positions of the working face of the caving area filling space and the arch feet of the semi-arch structure obtained by screening, dividing the filling operation of the caving area filling space into multiple filling windows includes: Obtain the positions of the working face of the caving area filling space and the arch feet of the semi-arch structure; the semi-arch structure is an arched stress partition formed by the deflection of the main stress of the overlying bedrock in the stope due to the periodic fracture of the roof during the mining process of the working face; According to the positions of the working face of the caving area filling space and the arch feet of the semi-arch structure, obtain the mining time of the filling operation of the caving area filling space, and divide the mining time into multiple filling windows.

[0011] Furthermore, before dividing the filling operation of the caving area filling space into multiple filling windows based on the positions of the working face of the caving area filling space and the arch feet of the semi-arch structure obtained by screening, it also includes: Pre-arrange a filling port at the boundary position of the caving area filling space corresponding to the arch foot of the semi-arch structure; the filling port includes multiple groups of filling boreholes and filling pipes; the filling boreholes are evenly distributed in the coal pillar between the gob-side entry and the caving area, and the filling pipes are reserved and arranged in the tail entry of the working face.

[0012] Further, before dividing the filling operation of the caving area filling space into multiple filling windows according to the positions of the working face of the caving area filling space and the arch foot of the semi-arch structure obtained by screening, it further includes: Arrange a filling system for the caving area, including: Connect the filling station with the filling pipeline, and sequentially introduce the filling pipeline into the underground main roadway and the gob-side entry; Connect the filling pipeline introduced into the gob-side entry to the filling port through a branch pipe, or after introducing the branch pipe into the tail entry of the working face, connect the branch pipe to the reserved filling pipe; Wherein, a distribution valve and an on-line detector are respectively arranged on each branch pipe, and the on-line detector is used for on-line monitoring of flow rate, pressure and viscosity.

[0013] Further, before sequentially performing the filling operation of each filling window period by using the backward fluidized filling method according to the sequence of the filling window periods, it further includes: Pre-prepare a filling material by using coal-based solid waste, and the filling material adopts a controllable low-strength material; wherein, the preparation process of the controllable low-strength material is as follows: Crush the coal-based solid waste raw material into graded particles; Uniformly mix the graded particles, the cementitious material and the water reducing agent according to a preset ratio, and add mine water after mixing to prepare a controllable low-strength material; Wherein, the coal-based solid waste raw material is coal gangue or a combination of coal gangue and at least one of fly ash, slag, gasification slag, and desulfurization gypsum; The graded particles are continuously graded particles with a particle size less than 5 mm, and the mass proportion of the particle size particles less than 0.3 mm in the total mass of the continuously graded particles is at least 15%.

[0014] Further, the coal-based solid waste raw material includes coal gangue, and the mass proportion of coal gangue in the total mass of the coal-based solid waste raw material is at least 60%.

[0015] Further, the mass concentration of the controllable low-strength material is 72% - 77%, the slump ≥ 220 mm, and the mass ratio of the water reducing agent to the cementitious material is 0.3% - 0.6%; when the controllable low-strength material is incorporated with a low-activity cementitious material, the mass of the cementitious material is the total mass of cement and the low-activity cementitious material; the low-activity cementitious material is at least one of fly ash, slag powder and blast furnace slag powder.

[0016] Further, according to the sequence of the filling window period, the retreating fluidized filling method is adopted to perform the filling operation for each filling window period in turn. After the filling operation corresponding to the last filling window period is completed, it includes: Based on the calculated caving zone filling rate and the subsidence amount of the damage control layer, the collaborative waste reduction and extraction effect of fluidized filling in the caving zone is characterized to achieve effect evaluation.

[0017] Further, before the collaborative waste reduction and extraction effect of fluidized filling in the caving zone is characterized based on the calculated caving zone filling rate and the subsidence amount of the damage control layer, it further includes: Based on the volume of the filling material filled into the caving zone and the filling space in the caving zone, the caving zone filling rate is calculated. The specific formula is as follows:

[0018] In the formula, η ct is the caving zone filling rate; V ct is the volume of the filling material filled into the caving zone; V 1 represents the volume of coal seam mined out; V 2 represents the volume of surface subsidence; V 3 represents the unloading and swelling volume of the fissure zone and the bending subsidence zone; k represents the space utilization coefficient of the caving zone; Based on the subsidence amount of the damage control layer before filling, the compaction rate of the composite filling body, the bulking coefficient of the caving rock mass, and the total thickness of the strata in the caving zone, the subsidence amount of the damage control layer is calculated. The specific formula is as follows:

[0019] In the formula, w j is the subsidence amount of the damage control layer; w z is the subsidence amount of the damage control layer before filling; η c is the compaction rate of the composite filling body; K p is the bulking coefficient of the caving rock mass; ∑ h is the total thickness of the strata in the caving zone.

[0020] Compared with the prior art, the present invention has the following beneficial effects: The present invention provides a method for collaborative loss reduction mining by fluidized filling disposal in the caving area of coal-based solid waste. First, by matching the positive equilibrium relationship between the volume of the pre-prepared filling material of coal-based solid waste and the filling space in the caving area, a filling space with appropriate size is screened out. Secondly, according to the position of the working face and the arch feet of the semi-arch structure, the filling operation is divided into multiple filling windows. Finally, the backstepping fluidized filling method is used to sequentially complete the filling of each window. In this method, the positive equilibrium matching of volume ensures the dynamic balance between the material and the space, reducing the influence of the void change in the caving area on the system; the division of filling windows utilizes the mechanical support advantage of the semi-arch structure to provide a stable filling environment; the backstepping filling simulates the natural compaction process in the caving area, maintaining the continuity and uniformity of the operation. Using this method improves the source disposal efficiency of solid waste, reduces the material preparation cost, optimizes the utilization rate of space resources in the caving area, strengthens the synergy between waste storage and loss reduction mining, and thus effectively alleviates the ecological environment damage problems caused by surface solid waste stacking and underground goafs.

[0021] In the present invention, preferably, based on the accurate calculation of the coal seam extraction volume, the surface subsidence volume, and the unloading and swelling volumes in the fracture zone and the bending subsidence zone, combined with the space utilization coefficient determined by the filling test, a dynamic matching model is constructed, which can realize the scientific adaptation of the volume of the filling material and the filling space, and improve the economic and environmental benefits of the filling effect.

[0022] In the present invention, preferably, the filling windows are dynamically divided according to the position of the working face and the arch feet of the semi-arch structure, so that the filling operation is synchronized with the dynamic compaction process in the caving area, avoiding uneven filling caused by the change of the void structure, and improving the gangue storage capacity in the caving area and the mechanical properties of the compaction force of the caving rock mass.

[0023] In the present invention, preferably, a charging port is preset at the boundary of the caving area corresponding to the arch feet of the semi-arch structure, and precise filling is realized through multiple groups of drill holes and filling pipelines, reducing the influence of the temporal and spatial interference between mining and filling, improving the filling efficiency, and at the same time avoiding construction risks and ensuring the safety of operating personnel.

[0024] In the present invention, preferably, an underground filling pipe network and branch pipeline system are constructed, equipped with a distribution valve and an on-line detector, to realize the real-time monitoring and dynamic regulation of the flow rate, pressure, and viscosity, ensure the continuity and uniformity of the filling process, and improve the filling quality.

[0025] In the present invention, preferably, through the crushing and grading design of the coal-based solid waste raw materials, combined with the optimized proportion of the cementitious material and the additive, a controllable low-strength material with good fluidity is prepared, reducing the solid waste treatment cost, and at the same time improving the engineering properties and environmental benefits of the filling material.

[0026] In the present invention, preferably, the minimum proportion of coal gangue in the coal-based solid waste raw materials is specified to ensure the aggregate stability of the controllable low-strength material, promote the large-scale resource utilization of coal gangue, and reduce the pressure of solid waste stacking.

[0027] In the present invention, preferably, by incorporating low-activity cementitious materials such as fly ash and slag powder, the cementitious system of the controlled low-strength material is optimized, the cement consumption is reduced, carbon emissions are reduced, and at the same time, the stability of the caving area is improved.

[0028] In the present invention, preferably, a quantitative evaluation system for the filling rate of the caving area and the subsidence amount of the damage reduction control layer is established to achieve accurate evaluation of the filling effect, provide a scientific basis for optimizing the filling process and adjusting the mining plan, and promote the standardization and regularization development of the fluidized filling technology for coal-based solid waste caving areas. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 It is a flow chart of a fluidized filling disposal and collaborative damage reduction mining method for coal-based solid waste caving areas provided by an embodiment of the present invention; Figure 2 It is a schematic structural diagram related to the pre-mining space collaboration provided by an embodiment of the present invention; Figure 3 It is a schematic structural diagram related to the mining and filling process collaboration provided by an embodiment of the present invention; Figure 4 It is a flow chart of a fluidized filling disposal and collaborative damage reduction mining method for coal-based solid waste caving areas provided by the present invention.

[0030] REFERENCE SIGNS: 1, Coal seam mined volume; 2, Surface subsidence volume; 3, Unloading and swelling volume of the fracture zone and the bending subsidence zone; 4, Semi-arch structure; 5, Caved gangue; 6, Arch foot; 7, Working face; 8, Caving area; 9, Gob-side entry; 10, Coal pillar; 11, Filling borehole; 12, Filling pipe; 13, Filling station; 14, Main filling pipe; 15, Branch pipe; 16, Online detector; 17, Underground main roadway; 18, Coal-based solid waste raw material; 19, Crushing device; 20, Preparation bin; 21, Mine water; 22, Composite filling body; 23, Damage reduction control layer. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0031] The following explanations are given for the technical terms involved in the present invention: CLSM: The full name is Controlled Low-Strength Material, that is, the coal-based solid waste controlled low-strength material, which refers to a filling material with controllable low-strength characteristics made by using coal-based solid waste (such as coal gangue, fly ash, etc.) as the main raw material, adding appropriate amounts of cementitious materials, mine water and additives, and mixing them in a preset ratio.

[0032] Coal-based solid waste: It is the solid waste generated during the coal mining and processing process. Its large-scale accumulation not only occupies land but also damages the surface ecological environment.

[0033] The embodiment provides a method for collaborative loss reduction mining with fluidized filling disposal in the caving area of coal-based solid waste. Based on the disposal requirements of coal-based solid waste in and around the mine and the dynamic evolution law of the caving area in the mine, a pre-mining space collaboration - mining and filling process collaboration - waste storage loss reduction collaboration system is formed in sequence. During the dynamic compaction process of the caving area after coal seam extraction, within the determined filling window period, fluidized filling of the caving area with CLSM is safely implemented through the filling system, thereby filling and cementing the insufficiently compacted space in the caving area, modifying and strengthening the compressive mechanical properties of the caved rock mass, improving the stability of the caving area, and ultimately realizing the collaborative loss reduction mining of green and efficient disposal of coal-based solid waste at the source, such as Figure 4 shown, the method includes: Based on the positive equilibrium relationship between the volume of the filling material and the filling space in the caving area, the volume of the filling material is matched with the filling space in the caving area to screen out the filling space in the caving area that meets the conditions; the filling material is pre-prepared based on the coal-based solid waste to be filled and disposed in and around the mine; the filling space in the caving area is calculated based on the coal seam extraction volume, surface subsidence volume, and unloading expansion volume of the fracture zone and the bending subsidence zone; Based on the positions of the working face 7 and the arch feet 6 of the semi-arch structure of the filling space in the caving area screened out, the filling operation of the filling space in the caving area is divided into multiple filling window periods; According to the sequence of the filling window periods, the filling operation of each filling window period is carried out in turn by the backward fluidized filling method until the filling operation corresponding to the last filling window period is completed.

[0034] The following further illustrates the optimization method provided in this embodiment with reference to the accompanying drawings: As Figure 1 shown, this embodiment provides a method for collaborative loss reduction mining with fluidized filling disposal in the caving area of coal-based solid waste, including three processes: pre-mining space collaboration, mining and filling process collaboration, and waste storage loss reduction collaboration. According to the description in the embodiment content and combined with the engineering geological and mining conditions of a certain coal mine, specific implementation is described.

[0035] In this embodiment, a working face 7 of a certain coal mine is being mined. For the caving area during the mining process of this working face 7, the method for collaborative loss reduction mining with fluidized filling disposal in the caving area of coal-based solid waste is implemented.

[0036] S1. First, carry out the pre-mining space collaboration process.

[0037] As Figure 2As shown in the figure, in this embodiment, the types, properties, annual fixed emissions and disposal status of coal-based solid wastes discharged by the mine and surrounding industrial and mining enterprises in the past three years are investigated and statistically analyzed. The production plan and the upper limit of the increased solid waste in the next five years are predicted to determine the final solid waste disposal requirements. Based on the coal-based solid waste disposal requirements of the mine and its surrounding areas and combined with the characteristics of the filling working conditions, the basic formula of CLSM is selected and the volume of the filling material is calculated. V f ; Coordinate the layout of the amount of coal-based solid waste to be filled and disposed of each year and the caving area space that meets the requirements of fluidized filling to ensure the volume of the prepared, pumped, and filled materials. V f And the caving area filling space V c Are in positive balance, that is, the volume of the filling material is matched with the caving area filling space, and the caving area filling space that meets the conditions is screened; The specific conditions to be met are as follows:

[0038] In the formula, the caving area filling space is in a dynamic change state with the mining of the working face 7, and is composed of the volume of coal seam mined out 1 (represented by V 1), the surface subsidence volume 2 (represented by V 2), the unloading and swelling volume 3 of the fracture zone and the bending subsidence zone (represented by V 3) and the caving area space utilization coefficient k Decided.

[0039] The specific calculation expression is ; In the formula, the caving area space utilization coefficient k Comprehensively reflects the difficulty of fluidized filling and waste storage in the caving area under different geological and mining conditions, and is determined according to the filling test.

[0040] So far, the caving area filling space that meets the conditions has been screened.

[0041] It should be noted that in this embodiment, the caving area filling space is calculated based on the coal seam extraction volume, the surface subsidence volume, and the unloading expansion volume of the fissure zone and the bending subsidence zone. In the current industry, most studies on the subsidence of the overlying strata in the goaf use the elastic thin plate theory and the key stratum theory, and indirectly equivalent to approximate expressions such as residual bulking, separation height, and superimposed goaf height based on the subsidence trajectory of the key stratum to represent the caving area filling space, which has certain limitations. This embodiment adopts the method of calculating the caving area filling space through the coal seam extraction volume, the surface subsidence volume, and the unloading expansion volume of the fissure zone and the bending subsidence zone, avoiding the limitations of dividing the filling area according to the maximum subsidence amount of the grout-controlled filling rock group and empirical parameters, and then calculating the filling space of each area segment by segment, which can greatly reduce the deviation between the result and the actual situation, and increase the accuracy and practicability of the calculation.

[0042] In this embodiment, based on the positions of the working face 7 of the caving area filling space and the arch feet 6 of the semi-arch structure screened, the filling operation of the caving area filling space is divided into multiple filling windows; among them, the semi-arch structure is an arched stress partition formed by the deflection of the main stress of the overlying bedrock in the stope due to the periodic fracture of the roof during the mining process of the working face. This arched stress partition has a certain thickness and is located above the fracture arch. It is a bedrock stress arch structure shaped like an arch and is also a load-bearing structure to ensure the efficient filling of the caving area. Adopting this method can strengthen the important influence of the semi-arch structure on the dynamic compaction of the caving area and the continuous evolution of voids, and then scientifically guide the division of the caving area filling space and efficient filling.

[0043] S2. Carry out the collaborative process of the mining and filling process.

[0044] Combined with Figure 2 、 Figure 3 As shown in S21. Determination of the filling window: According to the stress monitoring data of the caving area of the adjacent working face 7, the position of the arch feet 6 of the semi-arch structure 4 above the working face 7 during the mining process of the working face 7 can be determined. The mining time from the position of the arch feet 6 to the current position of the working face 7 is divided into the 1st, 2nd... n th filling windows in sequence, and a filling material port connecting the caving area 8 is pre-arranged at the boundary position of the caving area 8 corresponding to the arch feet 6. Among them, the filling material port is composed of multiple groups of filling boreholes 11 uniformly arranged in the coal pillar 10 between the gob-side entry 9 and the caving area 8 and the filling pipe 12 reserved in the tail gateway.

[0045] S22. Filling system layout: The filling system consists of a filling station 13, a main filling pipe 14, branch pipes 15, a distributing valve, and an on-line detector 16 for detecting flow rate, pressure, and viscosity. The filling station 13 is connected to the main filling pipe 14 and extends to the underground main roadway 17, then is introduced into the gob-side entry 9, and then connected to the filling ports through a number of branch pipes 15, or introduced into the tail entry of the working face 7 and connected to the reserved filling pipe 12. A set of distributing valves and on-line detectors 16 are installed on each branch pipe 15.

[0046] S23. CLSM preparation: The coal-based solid waste raw material 18 is crushed by a crushing device 19 to meet the particle size grading requirements, and then stored in a stock bin 20 together with cement and a water reducer respectively. After being uniformly mixed according to the design ratio, mine water 21 is added to prepare CLSM, with a mass concentration of 72% - 77%, a slump of ≥220 mm, a coal gangue content of ≥60%, and a mass ratio of the water reducer to the cementitious material of 0.3% - 0.6%. In this embodiment, the particle size grading of coal gangue and the water reducer are used to jointly adjust the fluidity of CLSM, and its fluidity must meet the minimum pumping requirements, which are monitored in real time by the on-line detector 16. Among them, other additives can also be used as the water reducer, and other additives include suspending agents, stabilizers, thickeners, and accelerating agents.

[0047] Exemplarily, in S23, the coal-based solid waste raw material is coal gangue or a combination of coal gangue and at least one of fly ash, slag, gasification slag, and desulfurized gypsum. Among them, after the coal-based solid waste raw material 18 is crushed, it must be continuous grading particles with a particle size less than 5 mm, and the proportion of particles with a particle size less than 0.3 mm in the total mass of the continuous grading particles is at least 15%, which is beneficial to increasing the cohesiveness of CLSM.

[0048] It should be noted that the execution order of the steps of S22 and S23 can also be carried out before S21. Since the steps of S22 and S23 are pre-execution steps, they only need to be completed before the formal filling operation starts.

[0049] S24. Fluidized filling: By controlling the opening sequence and opening time of the distributing valves on each branch pipe 15, the backward fluidized filling of the caving area is realized. At the same time, during each filling window period, the prepared CLSM is safely and smoothly filled into the filling space of the caving area. The filling speed should adapt to the mining speed of the working face 7, that is, by controlling the filling flow rate, the diffusion speed of CLSM in the filling space is made consistent with the mining speed of the working face 7.

[0050] After the filling operation of the current filling window period is completed, repeat the fluidized filling operation of the next filling window period until all the caving areas 8 are filled.

[0051] Exemplarily, in S23, if low-activity cementitious materials such as fly ash, slag powder, and slag powder are added to the CLSM, the mass of the cementitious materials is the total mass of the cement and the low-activity cementitious materials.

[0052] As a preferred solution of this embodiment, CLSM is prepared: coal-based solid waste raw material 18 is crushed by crushing device 19 to meet the particle size distribution requirements, and then stored in preparation bin 20 with cement and water reducer respectively, and evenly mixed according to the designed ratio, and then added with mine water 21 to prepare CLSM, whose mass concentration is 77%, slump is 220 mm, coal gangue content is 67%, and the mass ratio of water reducer to cementitious material is 0.3%. In this embodiment, the fluidity of CLSM is adjusted by linkage between coal gangue particle size distribution and water reducer, and its fluidity must meet the minimum pumping requirements, which is monitored in real time by online detector 16.

[0053] The coal-based solid waste raw material 18 is coal gangue, wherein the coal-based solid waste raw material 18 must be crushed into continuous graded particles with a particle size of less than 5 mm, wherein the mass of particles with a particle size of less than 0.3 mm accounts for 15% of the total mass of the continuously graded particles.

[0054] As another preferred solution of this embodiment, CLSM preparation: coal-based solid waste raw material 18 is crushed by crushing device 19 to meet the particle size distribution requirements, and then stored in preparation bin 20 with cement and water reducer respectively, and evenly mixed according to the designed ratio, and then added with mine water 21 to prepare CLSM, whose mass concentration is 75%, slump 240 mm, coal gangue content 65%, and the mass ratio of water reducer to cementitious material is 0.3%. In this embodiment, the fluidity of CLSM is adjusted by linkage between coal gangue particle size distribution and water reducer, and its fluidity must meet the minimum pumping requirements, which is monitored in real time by online detector 16. The coal-based solid waste raw materials 18 are coal gangue and fly ash, wherein the coal-based solid waste raw materials 18 must be crushed into continuous graded particles with a particle size of less than 5 mm, wherein the mass of particles with a particle size of less than 0.3 mm accounts for 18% of the total mass of the continuously graded particles.

[0055] As another preferred solution of this embodiment, CLSM preparation: coal-based solid waste raw material 18 is crushed by crushing device 19 to meet the particle size distribution requirements, and then stored in preparation bin 20 with cement and water reducer respectively, and evenly mixed according to the designed ratio, and then added with mine water 21 to prepare CLSM, whose mass concentration is 75%, slump is 260 mm, coal gangue content is 63%, and the mass ratio of water reducer to cementitious material is 0.4%. In this embodiment, the fluidity of CLSM is adjusted by linkage between coal gangue particle size distribution and water reducer, and its fluidity must meet the minimum pumping requirements, which is monitored in real time by online detector 16. The coal-based solid waste raw material 18 is coal gangue, fly ash and slag. Among them, the coal-based solid waste raw material 18 must be continuously graded particles with a particle size less than 5 mm after crushing. Among them, the proportion of particles with a particle size less than 0.3 mm in the total mass of the continuously graded particles is 18%.

[0056] As another preferred solution of this embodiment, the CLSM is prepared as follows: The coal-based solid waste raw material 18 is crushed by the crushing device 19 to meet the particle size grading requirements, and then stored in the batching bins 20 with cement and water reducer respectively. After being uniformly mixed according to the designed ratio, mine water 21 is added to prepare the CLSM. Its mass concentration is 73%, the slump is 260 mm, the coal gangue content is 60%, and the mass ratio of the water reducer to the cementitious material is 0.4%. In this embodiment, the particle size grading of coal gangue and the water reducer are used to jointly adjust the fluidity of the CLSM, and its fluidity must meet the minimum pumping requirements, which are monitored in real time by the on-line detector 16. The coal-based solid waste raw material 18 is coal gangue, fly ash, gasification slag and desulfurized gypsum. Among them, the coal-based solid waste raw material 18 must be continuously graded particles with a particle size less than 5 mm after crushing. Among them, the proportion of particles with a particle size less than 0.3 mm in the total mass of the continuously graded particles is at least 18%.

[0057] As another preferred solution of this embodiment, the CLSM is prepared as follows: The coal-based solid waste raw material 18 is crushed by the crushing device 19 to meet the particle size grading requirements, and then stored in the batching bins 20 with cement and water reducer respectively. After being uniformly mixed according to the designed ratio, mine water 21 is added to prepare the CLSM. Its mass concentration is 72%, the slump is 270 mm, the coal gangue content is 60%, and the mass ratio of the water reducer to the cementitious material is 0.6%. In this embodiment, the particle size grading of coal gangue and the water reducer are used to jointly adjust the fluidity of the CLSM, and its fluidity must meet the minimum pumping requirements, which are monitored in real time by the on-line detector 16.

[0058] The coal-based solid waste raw material 18 is coal gangue, fly ash, slag, gasification slag and desulfurized gypsum. Among them, the coal-based solid waste raw material 18 must be continuously graded particles with a particle size less than 5 mm after crushing. Among them, the proportion of particles with a particle size less than 0.3 mm in the total mass of the continuously graded particles is 20%.

[0059] S3. Carry out the collaborative process of waste storage and loss reduction.

[0060] In this process, the filling rate of the caving area η ct and the subsidence amount of the loss reduction control layer w j are used to characterize the collaborative waste storage and loss reduction mining effect of the fluidized filling in the caving area. As Figure 3As shown in the figure, the composite filling body 22 is a new pressure-bearing structure formed by the broken rock mass in the caving area and the cemented and solidified CLSM filled therein; the loss reduction control layer 23 is the low key layer at the lower part of the fissure zone and directly connected to the regular caving zone after the caving area is formed. The loss reduction control layer 23 is in direct contact with the composite filling body 22, and the two are closely related. The filling rate of the caving area and the subsidence amount of the loss reduction control layer are calculated as follows:

[0061]

[0062] In the formula, V ct is the volume of CLSM filled into the caving area; w z is the subsidence amount of the loss reduction control layer before filling, which can be obtained through on-site observation; η c is the compaction rate of the composite filling body, which is used to reflect the final compaction state after filling the caving area. The relationship between the compaction rate of the composite filling body and the filling rate η ct is obtained through the compaction deformation experiment of the composite filling body 22; K p is the swelling coefficient of the caving rock mass; ∑ h is the total thickness of the strata in the caving zone.

[0063] As another preferred solution of this embodiment, on the premise of clarifying the subsidence reduction index of the loss reduction control layer 23, the compaction rate of the designed composite filling body w j can be fed back, and then the filling rate of the caving area η c or the dosage of the gelling material in CLSM can be secondarily regulated through the compaction deformation experiment of the composite filling body. η ct

[0064] It can be seen that the fluidized filling disposal and collaborative subsidence reduction mining method for the caving area of coal-based solid waste provided by this embodiment has the following advantages compared with the prior art: First, in this method, CLSM is filled during the dynamic compaction process of the caving area after coal seam extraction. Based on the disposal requirements of coal-based solid waste in and around the mine and the dynamic evolution law of the mine caving area, the spatial resource value of the mine caving area and the filling property of coal-based solid waste materials are fully utilized, and the filling space in the caving area is scientifically arranged, so as to achieve a positive balance between the utilization of the spatial resources in the caving area and the source disposal of solid waste.

[0065] ​Second, this method implements the collaborative loss reduction mining of coal-based solid waste caving fluidized filling disposal by forming a pre-mining space coordination - mining and filling process coordination - storage and waste reduction coordination system, which can adapt to the source green and efficient disposal and loss reduction mining of multi-source coal-based solid waste, effectively solve the problems of a large amount of gangue stacking on the ground and the formation of large underground goafs exacerbating the destruction of the mining area's ecological environment, and has the characteristics of high waste storage efficiency, high-efficiency coordination of waste storage and loss reduction, and remarkable economic benefits.

[0066] The above embodiments are only one of the implementation manners that can realize the technical solution of the present invention. The scope of protection required by the present invention is not only limited by this embodiment, but also includes any changes, substitutions and other implementation manners that are easily conceivable by those skilled in the art within the technical scope disclosed by the present invention.

[0067] Finally, it should be noted that the above embodiments are only used to illustrate the technical solution of the present invention and not to limit it. Although the present invention has been described in detail with reference to the above embodiments, those of ordinary skill in the art should understand that: still can modify the specific implementation manners of the present invention or make equivalent substitutions, and any modification or equivalent substitution that does not deviate from the spirit and scope of the present invention shall be covered by the protection scope of the claims of the present invention.

Claims

1. A method for collaborative loss reduction mining with fluidized filling disposal in the caving area of coal-based solid waste, characterized in that, Including: Based on the positive equilibrium relationship between the volume of the filling material and the filling space in the caving area, the volume of the filling material is matched with the filling space in the caving area to screen out the filling space in the caving area that meets the conditions; the filling material is pre-prepared based on the coal-based solid waste to be filled and disposed of in the mine and its surrounding areas. The filling space in the caving area is calculated based on the coal seam extraction volume, the surface subsidence volume, and the unloading expansion volume of the fissure zone and the bending subsidence zone. Based on the positions of the working face of the filling space in the caving area screened out and the arch feet of the semi-arch structure, the filling operation of the filling space in the caving area is divided into multiple filling time windows. According to the sequence of the filling time windows, the backstepping fluidized filling method is used to sequentially carry out the filling operations for each filling time window until the filling operation corresponding to the last filling time window is completed.

2. The method for collaborative loss reduction mining by fluidized filling disposal in the caving area of coal-based solid waste according to claim 1, characterized in that, The matching of the volume of the filling material with the filling space in the caving area based on the positive equilibrium relationship between the volume of the filling material and the filling space in the caving area includes: According to the positive equilibrium relationship between the volume of the filling material and the filling space in the caving area, the volume of the filling material is matched with the filling space in the caving area. The specific expression of the positive equilibrium relationship is as follows: In the formula, V c represents the caving area filling space; V f represents the volume of the filling material; The calculation formula of the filling space in the caving area is as follows: In the formula, V 1 represents the mined volume of the coal seam; V 2 represents the surface subsidence volume; V 3 represents the unloading and swelling volume of the fractured zone and the bending subsidence zone; k represents the space utilization coefficient of the caving area, and the space utilization coefficient of the caving area is obtained from the filling test.

3. The method for collaborative loss reduction mining by fluidized filling disposal in the caving area of coal-based solid waste according to claim 1, wherein The division of the filling operation of the filling space in the caving area into multiple filling time windows based on the positions of the working face of the filling space in the caving area screened out and the arch feet of the semi-arch structure includes: Obtain the positions of the working face of the filling space in the caving area and the arch feet of the semi-arch structure; the semi-arch structure is an arched stress partition formed by the deflection of the main stress of the overlying bedrock in the stope due to the periodic fracture of the roof during the mining process of the working face. According to the positions of the working face of the filling space in the caving area and the arch feet of the semi-arch structure, obtain the mining time of the filling operation of the filling space in the caving area, and divide the mining time into multiple filling time windows.

4. The method for collaborative loss reduction mining by fluidized filling disposal in the caving area of coal-based solid waste according to claim 3, wherein Before the division of the filling operation of the filling space in the caving area into multiple filling time windows based on the positions of the working face of the filling space in the caving area screened out and the arch feet of the semi-arch structure, it also includes: Pre-arrange a filling material inlet at the boundary position of the filling space in the caving area corresponding to the arch feet of the semi-arch structure; the filling material inlet includes multiple groups of filling boreholes and filling pipes; the filling boreholes are evenly distributed in the gob-side entry and the coal pillar between the goaf and the working face, and the filling pipes are reserved and arranged in the tailgate of the working face.

5. The fluidized filling disposal and collaborative loss reduction mining method for gob areas of coal-based solid waste according to claim 4, characterized in that Before the division of the filling operation of the filling space in the caving area into multiple filling time windows based on the positions of the working face of the filling space in the caving area screened out and the arch feet of the semi-arch structure, it also includes: Arrange the filling system for the caving area, including: Connect the filling station with the filling pipeline, and sequentially introduce the filling pipeline into the underground main roadway and the gob-side entry. Connect the filling pipeline introduced into the gob-side entry to the filling material inlet through a branch pipe, or after introducing the branch pipe into the tailgate of the working face, connect the branch pipe to the reserved filling pipe. Among them, a distribution valve and an on-line detector are respectively arranged on each branch pipe, and the on-line detector is used for on-line monitoring of flow rate, pressure and viscosity.

6. The coal-based solid waste caving area fluidized filling disposal and collaborative loss reduction mining method according to claim 1, characterized in that Before the sequential filling operations for each filling time window are carried out using the backstepping fluidized filling method according to the sequence of the filling time windows, it also includes: Preparing backfill materials with coal-based solid waste in advance, and the backfill materials adopt controlled low-strength materials; wherein, the preparation process of the controlled low-strength materials is as follows: Crushing the coal-based solid waste raw materials into graded particles; Uniformly mixing the graded particles, the cementitious material and the water reducer according to a preset ratio, and adding mine water after mixing to prepare the controlled low-strength materials; Wherein, the coal-based solid waste raw materials are coal gangue or a combination of coal gangue and at least one of fly ash, slag, gasification slag, and desulfurized gypsum; The graded particles are continuously graded particles with a particle size less than 5 mm, and the mass proportion of particles with a particle size less than 0.3 mm in the total mass of the continuously graded particles is at least 15%.

7. The fluidized filling disposal and collaborative loss reduction mining method for gob areas of coal-based solid waste according to claim 6, wherein The coal-based solid waste raw materials include coal gangue, and the mass proportion of coal gangue in the total mass of the coal-based solid waste raw materials is at least 60%.

8. The method for collaborative loss reduction mining by fluidized filling disposal in the caving area of coal-based solid waste according to claim 6, characterized in that, The mass concentration of the controlled low-strength materials is 72% - 77%, the slump ≥ 220 mm, and the mass ratio of the water reducer to the cementitious material is 0.3% - 0.6%; when low-activity cementitious materials are incorporated into the controlled low-strength materials, the mass of the cementitious material is the total mass of cement and low-activity cementitious materials; the low-activity cementitious materials are at least one of fly ash, slag powder, and blast furnace slag powder.

9. The method for collaborative loss reduction mining by fluidized filling disposal in the caving area of coal-based solid waste according to claim 1, wherein According to the sequence of the filling windows, adopting the backward fluidized filling method to carry out the filling operations for each filling window in turn. After completing the filling operation corresponding to the last filling window, it includes: Based on the calculated filling rate of the caving area and the subsidence amount of the loss reduction control layer, characterizing the collaborative waste reduction and loss reduction mining effect of fluidized filling in the caving area to achieve effect evaluation.

10. The fluidized filling disposal and collaborative loss reduction mining method for the caving area of coal-based solid waste according to claim 9, characterized in that, Before characterizing the collaborative waste reduction and loss reduction mining effect of fluidized filling in the caving area based on the calculated filling rate of the caving area and the subsidence amount of the loss reduction control layer, it also includes: Based on the volume of the backfill materials filled into the caving area and the filling space of the caving area, calculating the filling rate of the caving area. The specific formula is as follows: In the formula, η ct is the caving area filling rate; V ct is the volume of the filling material filled into the caving area; V 1 represents the volume of coal seam mined out; V 2 represents the surface subsidence volume; V 3 represents the unloading and swelling volume of the fractured zone and the bending subsidence zone; k represents the space utilization coefficient of the caving area; Based on the subsidence amount of the loss reduction control layer before filling, the compaction rate of the composite backfill body, the swelling coefficient of the caving rock mass, and the total thickness of the caving zone rock stratum, calculating the subsidence amount of the loss reduction control layer. The specific formula is as follows: In the formula, w j is the subsidence amount of the damage control layer; w z is the subsidence amount of the damage control layer before filling; η c is the compaction rate of the composite filling body; K p is the bulking factor of the caving rock mass; ∑ h is the total thickness of the strata in the caving zone.

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