A trinity water-saving coal mining method for ecologically fragile mining areas

Abstract

The invention belongs to the technical field of coal mining, and specifically relates to a three-in-one water-preserving coal mining method in an ecologically fragile mining area. Firstly, the spatial occurrence characteristics and geological data of three strata of a mining coal seam, an overlying room-type goaf and an ecological water level protection layer in a designed area are collected; then, a theoretical analysis is conducted on the degree of damage of the mining of the coal seam to the overlying room-type coal pillar and the ecological water level; finally, a cementing material is used to control the filling of the mining coal seam goaf, the overlying room-type goaf and the ecological water level protection layer by adopting a ground drilling pumping and layered filling method, thereby realizing the three-in-one water-preserving coal mining of the mining coal seam, the room-type goaf and the ecological water level protection layer; the method of the invention is suitable for coal mining and ecological water level protection under the room-type goaf of a shallow buried coal seam in an ecologically fragile mining area, and provides a brand-new technical means for protecting the ecological water level and surface environment in the ecologically fragile mining area, and the method is simple and efficient, requires little equipment investment and is low in cost, and has broad application prospects.

Description

Technical Field

[0001] The invention belongs to the technical field of coal mining, and in particular relates to a three-in-one water-preserving coal mining method in ecologically fragile mining areas. Background Art

[0002] Coal occupies a dominant position in my country's energy structure and is an important part of my country's energy strategic security. With the depletion of coal resources in the eastern mining areas, the western mining areas have become an important strategic base for my country's coal energy supply. The ecologically fragile western mining areas are rich in coal resources, with thick coal seams, shallow burial depth, a large number of mineable coal seams, good coal quality, and easy mining. They are important coal production areas in China. In the early stage, some areas of the western mining areas mainly adopted the room-type coal mining method for mining. A large number of room-type coal pillars were left in the goaf. When the lower coal seams were mined, it was easy to cause the overlying room-type coal pillars to become unstable and damaged, which in turn caused the shallow aquiclude structure to be damaged, the ecological water level to drop, and the ecological environment to deteriorate.

[0003] Therefore, how to provide a method for selective filling of three strata: coal seam goaf, overlying house-type goaf and ecological water level rock layer to achieve water-saving coal mining with three-in-one control is of great significance for the safe and efficient mining of coal resources and the protection of water resources in ecologically fragile mining areas. Summary of the invention

[0004] The purpose of the present invention is to overcome the above-mentioned problems existing in the traditional technology and provide a three-in-one water-preserving coal mining method in ecologically fragile mining areas.

[0005] In order to achieve the above technical objectives and the above technical effects, the present invention is implemented through the following technical solutions:

[0006] A three-in-one water-saving coal mining method for ecologically fragile mining areas, based on the spatial distribution characteristics and geological data of the three strata of the mined coal seam, the overlying room-type goaf and the ecological water level protection layer, analyzes and determines the degree of damage to the overlying room-type coal pillar and the ecological water level caused by coal seam mining, and controls the filling of the mined coal seam goaf, the overlying room-type goaf and the ecological water level protection layer through ground drilling pumping and layered filling methods.

[0007] Furthermore, the three-in-one water-saving coal mining method in ecologically fragile mining areas as described above has the following specific steps:

[0008] S1. Investigate and collect mining geological data of the design area, master the spatial distribution characteristics of the three strata of mining coal seam, overlying room-type goaf and ecological water level protection layer, and conduct coal and rock mass sampling;

[0009] S2. Based on the test of physical and mechanical parameters of coal and rock mass, a numerical analysis model of coal seam mining and ecological water level impact under room-type goaf is constructed to study the impact of ecological water level at different layers and different filling rates;

[0010] S3. Based on the results of the ecological water level damage analysis, the coal seam goaf, overlying room-type goaf and ecological water level protection layer are filled and controlled by ground drilling pumping and layered filling methods;

[0011] S4, cycle operation, complete the filling operation of other boreholes, and realize the three-in-one water-saving coal mining of coal seam, room-type goaf and ecological water level protection layer.

[0012] Furthermore, in step S3, the degree of damage to the ecological water level is determined to be divided into the following three levels:

[0013] Level I: The ecological water level is less affected, the aquiclude is basically not damaged, and some cracks and abscission layers are developed;

[0014] Level II: The ecological water level drops, the aquiclude is basically destroyed, and some water-conducting fissures are formed;

[0015] Level III: The ecological water level has dropped significantly, the aquiclude has been severely damaged, and a large number of water-conducting fissures have been formed.

[0016] Furthermore, if the degree of damage to the ecological water level is level I, only one layer of the ecological water level protection layer is grouting-filled;

[0017] If the degree of damage to the ecological water level is level II, grouting and filling control will be carried out on the two layers of the room-type goaf and the ecological water level protection layer;

[0018] If the degree of damage to the ecological water level is level III, grouting filling control will be carried out on the three layers of the mined coal seam goaf, the overlying house-type goaf and the ecological water level protection layer.

[0019] Furthermore, in step S3, the filling material used for filling is at least one of gangue, aeolian sand, cement, water glass, and quick-setting agent, wherein the particle size of the coarse aggregate is controlled to be less than 0.15 mm.

[0020] Furthermore, no binder is added to the filling materials of the mined coal seam goaf; and binder is added to the filling materials of the overlying room-type goaf and the ecological water level protection layer, so as to achieve the purpose of filling control.

[0021] The beneficial effects of the present invention are:

[0022] Aiming at coal mining under room-type goaf in shallow coal seams and ecological water level protection in ecologically fragile mining areas, the present invention proposes selective filling of three strata: coal seam goaf, overlying room-type goaf and ecological water level rock strata, to achieve water-preserving coal mining with three-in-one control; the present invention provides a brand-new technical means for protecting ecological water levels and surface environments in ecologically fragile mining areas, and the technical method is simple and efficient, requires little equipment investment, and is low in cost, and has broad application prospects.

[0023] Of course, any product implementing the present invention does not necessarily need to achieve all of the above advantages at the same time. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings required for describing the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other accompanying drawings can be obtained based on these accompanying drawings without paying creative work.

[0025] Figure 1 It is a design flow chart of the present invention;

[0026] Figure 2 It is a numerical simulation model diagram of the present invention;

[0027] Figure 3 This is a simulation result diagram of the grouting filling of the ecological water level protection layer of the present invention;

[0028] Figure 4 This is a schematic diagram of the grouting filling principle of the ecological water level protection layer of the present invention;

[0029] Figure 5 It is a principle diagram of grouting filling of ecological water level protection layer and room-type goaf area of ​​the present invention;

[0030] Figure 6 It is a principle diagram of grouting and filling of ecological water level protection layer, room-type goaf area, and mining coal seam goaf area of ​​the present invention;

[0031] In the accompanying drawings, the reference numerals of the various components are as follows:

[0032] 1-aquifer, 2-aquiclude, 3-water-conducting fracture zone, 4-1# coal seam, 5-2# coal seam, 6-filling pipeline, I-ecological water level protection layer grouting filling, II-room-type goaf grouting filling, III-mining coal seam goaf grouting filling. DETAILED DESCRIPTION

[0033] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0034] The present invention discloses a three-in-one water-saving coal mining method for ecologically fragile mining areas, which is applicable to the method of coal mining and ecological water level protection under the room-type goaf area of ​​shallow buried coal seams in ecologically fragile mining areas. The steps of the method are: firstly, the spatial occurrence characteristics and geological data of the three strata of the mining coal seam, the overlying room-type goaf area and the ecological water level protection layer in the design area are collected; then, the degree of damage to the overlying room-type coal pillar and the ecological water level caused by coal seam mining is theoretically analyzed; finally, cementing materials such as gangue and aeolian sand are used, and the method of ground drilling pumping and layered filling is adopted to control the filling of the mining coal seam goaf area, the overlying room-type goaf area and the ecological water level protection layer, so as to realize the three-in-one water-saving coal mining of the mining coal seam, the room-type goaf area and the ecological water level protection layer, and provide a new technical means for the protection of the ecological water level and the surface environment in ecologically fragile mining areas. The technical method is simple and efficient, with low equipment investment and low cost, and has broad application prospects.

[0035] The relevant specific embodiments of the present invention are as follows:

[0036] Example 1

[0037] The designed production capacity of a mining area in the west is 1.2Mt / a. The main coal seams are 1# and 2#. The 1# coal seam is 98m deep and 5m thick on average. In the early stage, the room-type coal mining method was used for mining, and a large number of room-type coal pillars were left in the goaf. The 2# coal seam is 142m deep and 4m thick on average. During the mining of the 2# coal seam, it is necessary to consider the stability of the overlying room-type coal pillars, protect the shallow aquiclude structure, maintain the ecological water level, and achieve the purpose of protecting the surface vegetation and other ecological environments.

[0038] The specific steps are as follows:

[0039] 1) Collect geological conditions in the mine design area, including: the main mining coal seams are 1# coal seam and 2# coal seam, of which 1# coal seam is buried at a depth of 98m, 2# coal seam is buried at a depth of 142m, and the mining heights are 5m and 4m respectively; the aquifer is fine sandstone, and the impermeable layer is mudstone. The mining sequence is from shallow to deep, 1# coal seam adopts room-and-pillar mining method, and 2# coal seam adopts longwall working face mining. Understand the spatial distribution characteristics of the three strata of mining coal seam, overlying room-type goaf and ecological water level protection layer, and conduct coal and rock mass sampling;

[0040] 2) Laboratory test methods were used to study the key physical and mechanical parameters of the coal and rock mass in the designed mining area: bulk modulus / GPa, shear modulus / GPa, cohesion / MPa, tensile strength / MPa, internal friction angle / ° and density / kg·m 3 Etc., the specific parameters are shown in Table 1;

[0041] Table 1 Coal rock layer and physical and mechanical parameters

[0042]

[0043] Flac3D numerical simulation software was used to establish a numerical analysis model of coal mining and ecological water level impact under room-type goaf. The model length × width × height is: 400m × 200m × 150m. Figure 2 As shown; horizontal displacement is constrained on all sides, and vertical displacement is constrained on the bottom; the constitutive relationship adopts the Moore-Coulomb model. By simulating the mining process, the 1# coal seam is mined by room-and-pillar mining, and the 2# coal seam is mined by longwall working face. The degree of damage to the aquifer during the mining of the 2# coal seam is determined, and the degree of damage to the aquifer is judged to be level III. According to the process of a three-in-one water-saving coal mining method in an ecologically fragile mining area, the degree of damage to the aquifer by the grouting filling method is simulated, as shown in Figure 3 As shown in Figure 2, when only one layer of the ecological water level protection layer is grouting-filled, the ecological water level sinks by 1.2 m. Figure 4 As shown in the figure, when the two layers of the room-type goaf and the ecological water level protection layer are grouting-filled, the ecological water level sinks to 0.8m. Figure 5 As shown in the figure, when grouting filling is carried out on the three layers of the mined coal seam goaf, the overlying room-type goaf and the ecological water level protection layer, the ecological water level sinks by 0.2m, which does not affect the surface ecological environment. Figure 6 shown.

[0044] 3) Carry out grouting filling control on three layers: the mined coal seam goaf, the overlying house-type goaf and the ecological water level protection layer. The filling materials are generally composed of one or more of gangue, aeolian sand, cement, water glass and quick-setting agent, among which the coarse aggregate particle size is generally below 0.15mm; the filling materials in the mined coal seam goaf do not add binder, and the filling materials in the overlying house-type goaf and the ecological water level protection layer need to add binder to achieve the purpose of filling control; Figure 6 As shown, the space III of the goaf of the 2# coal seam working face is first filled with grouting, then the room-type goaf II of the 1# working face is filled with grouting, and finally the fracture area I of the ecological water level protection layer is cemented and filled to rebuild the impermeable layer, ultimately achieving the three-in-one water-saving coal mining.

[0045] (5) Circular operation is performed to complete the filling operation of other boreholes, so as to achieve the goal of water-saving coal mining by mining coal seams, room-type goaf areas and ecological water level protection layers.

[0046] The preferred embodiments of the present invention disclosed above are only used to help explain the present invention. The preferred embodiments do not describe all the details in detail, nor do they limit the invention to specific implementation methods. Obviously, many modifications and changes can be made according to the content of this specification. This specification selects and specifically describes these embodiments in order to better explain the principles and practical applications of the present invention, so that those skilled in the art can understand and use the present invention well. The present invention is limited only by the claims and their full scope and equivalents.

Claims

1. A three-in-one water-saving coal mining method for ecologically fragile mining areas, characterized in that: Based on the spatial distribution characteristics and geological data of the three strata of the mined coal seam, the overlying room-type goaf and the ecological water level protection layer, the damage degree of the coal seam mining to the overlying room-type coal pillar and the ecological water level is analyzed and determined, and the filling control of the mined coal seam goaf, the overlying room-type goaf and the ecological water level protection layer is carried out through the method of ground drilling pumping and layered filling; The specific steps are as follows: S1. Investigate and collect mining geological data of the design area, master the spatial distribution characteristics of the three strata of mining coal seam, overlying room-type goaf and ecological water level protection layer, and conduct coal and rock mass sampling; S2. Based on the test of physical and mechanical parameters of coal and rock mass, a numerical analysis model of coal seam mining and ecological water level impact under room-type goaf is constructed to study the impact of ecological water level at different layers and different filling rates; S3. Based on the results of the ecological water level damage analysis, the coal seam goaf, overlying room-type goaf and ecological water level protection layer are filled and controlled by ground drilling pumping and layered filling methods; S4, cycle operation, complete the filling operation of other boreholes, and realize the trinity of water-saving coal mining in coal seam, room-type goaf and ecological water level protection layer; In step S3, the degree of damage to the ecological water level is determined in the following three levels: Level I: The ecological water level is less affected, the aquiclude is basically not damaged, and some cracks and abscission layers are developed; Level II: The ecological water level drops, the aquiclude is basically destroyed, and some water-conducting fissures are formed; Level III: The ecological water level has dropped significantly, the aquiclude has been severely damaged, and a large number of water-conducting fissures have been formed; If the degree of damage to the ecological water level is level I, only one layer of the ecological water level protection layer is grouting controlled; If the degree of damage to the ecological water level is level II, grouting filling control is carried out on the two layers of the room-type goaf and the ecological water level protection layer; If the degree of damage to the ecological water level is level III, grouting filling control will be carried out on the three layers of the mined coal seam goaf, the overlying house-type goaf and the ecological water level protection layer.

2. The trinity water-saving coal mining method for ecologically fragile mining areas according to claim 1 is characterized by: In step S3, the filling material used for filling is at least one of gangue, aeolian sand, cement, water glass, and quick-setting agent, wherein the particle size of the coarse aggregate is controlled to be less than 0.15 mm.

3. The trinity water-saving coal mining method for ecologically fragile mining areas according to claim 2 is characterized by: No binder is added to the filling materials of the mined coal seam goaf; binder is added to the filling materials of the overlying room-type goaf and ecological water level protection layer to achieve the purpose of filling control.

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