Method for mining aquifer remediation by inducing chemical scaling in water conducting fractures

Abstract

The present application relates to coal mine water conservation mining technical field, specifically relates to a kind of water-fissure artificial induced chemical scale formation mining aquifer repair method;Chemical precipitation induction solution and mixed slurry are respectively recharged into mining damaged aquifer and water-fissure by perfusion borehole, make its and mixed slurry injected in water-fissure effectively converge and fully precipitate by diffusion effect of water-fissure zone top boundary key layer top interface separation to chemical precipitation induction reagent, iron and / or calcium chemical precipitation generated thereby can be consolidated together by adsorption, inclusion effect Particle grouting material, promote the formation of chemical scale formation in water-fissure, effectively block the leakage passage of mining aquifer, realize the ecological function repair and in-situ protection of coal mining area mining aquifer, can provide technical support for mining area coal mining water resources protection and ecological restoration;The present application has low engineering quantity, strong practicality, can effectively reduce the leakage degree of aquifer, and low cost.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of coal mine water-preserved mining, and particularly relates to a method for repairing a mining aquifer by artificially inducing chemical fouling in a water-conducting fissure. BACKGROUND

[0002] The movement and damage of overburden strata caused by coal seam mining and the development of water-conducting fissures are the root causes of the damage to underground aquifers. When the water-conducting fissures developed in the mining rock mass directly communicate with the aquifer, the aquifer will continuously drain through the water-conducting fissures to the underground goaf, thereby causing problems such as the decline of the water level of the aquifer and the difficulty of taking water from the surface. Therefore, plugging or repairing the water-conducting fissures that communicate with the aquifer to isolate the channel through which the aquifer leaks to the underground goaf is an important way to promote the ecological function recovery of the mining aquifer.

[0003] Grouting is a common technical means for fissure water plugging at present, but due to the special environment of the development of water-conducting fissures, the traditional grouting method is difficult to apply. The injected slurry is often prone to "run-off" to the goaf under the action of gravity flow, and although some high-molecular organic chemical materials can "stay" in the fissure channel and form a good plugging effect, they generally have problems such as high price and toxic pollution. Therefore, it is particularly important to seek a high-efficiency plugging process or method suitable for the large-area development of water-conducting fissures in the overburden strata.

[0004] Fouling is a common phenomenon in daily life and many engineering fields, which is a phenomenon that iron and / or calcium and other crystalline precipitates continuously adsorb surrounding particulate impurities and accumulate and adhere to the flow channel or interface to cause blockage under special circumstances. This chemical fouling phenomenon provides a train of thought for the efficient plugging of water-conducting fissures. At present, some studies have proposed methods for plugging and repairing underground aquifers by directly using Fe(OH)3, CaCO3 and other chemical precipitates. However, due to the wide range of development of water-conducting fissures and the large macroscopic opening, simple chemical precipitation is often difficult to stably consolidate in the water-conducting fissures, especially in the environment with water flow erosion; and a large amount of chemical precipitation is needed to repair large-opening water-conducting fissures, which significantly increases the cost.

[0005] Therefore, by fully learning from and using the generation mechanism of chemical fouling, it is proposed to inject mixed slurry and chemical precipitation inducing solution into the water-conducting fissure, promote the rapid generation of chemical fouling in the water-conducting fissure through the adsorption, wrapping and consolidation of the chemical precipitation on the particles of the grouting material, and thus form a plugging effect to block the water-conducting fissure and restore the ecological water supply function of the aquifer. In order to achieve the above-mentioned goal, it is necessary to carry out special design research on the method for repairing the mining aquifer by artificially inducing chemical fouling in the water-conducting fissure based on the development range and distribution characteristics of the water-conducting fissure in the overburden strata. SUMMARY

[0006] In order to overcome the deficiencies in the prior art, the present application provides a mining aquifer repair method of water flowing fracture artificial induction chemical scaling, the chemical precipitation induction solution and the mixed slurry are respectively backfilled into the mining damaged aquifer and the water flowing fracture through the perfusion borehole, the adsorption, wrapping and consolidation of the iron and / or calcium precipitate generated by the chemical reaction to the grouting material particles form the scaling effect, the water flowing fracture is quickly plugged, thereby blocking the channel of the aquifer downward leakage, promoting the recovery of the damaged aquifer groundwater level, and finally achieving the goal of ecological function repair of the mining aquifer.

[0007] Specifically, the method comprises the following steps: a. detecting the development of the water flowing fracture in the mining area, and delineating the water flowing fracture connected aquifer area; b. constructing the mixed slurry perfusion borehole and the chemical precipitation induction solution perfusion borehole in the water flowing fracture connected aquifer area; the mixed slurry perfusion borehole is arranged inside the mining boundary and in the separation fracture development range in the water flowing fracture zone, and penetrates into the water flowing fracture zone to a set depth; the chemical precipitation induction solution perfusion borehole is arranged inside or outside the mining boundary and near the mining boundary, and the terminal hole layer is located at the top interface of the key layer of the top boundary of the water flowing fracture zone; c. perfusing the mixed slurry into the water flowing fracture through the mixed slurry perfusion borehole, and perfusing the chemical precipitation induction solution into the aquifer through the chemical precipitation induction solution perfusion borehole; the chemical precipitation induction solution is prepared by mixing one or more of CO3 2- , SO4 2- , OH - with water; the mixed slurry is prepared by mixing inert grouting material with water; when the chemical precipitation induction solution contains CO3 2- , the mixed slurry needs to simultaneously mix the reagent containing Ca 2+ and / or iron ions; when the chemical precipitation induction solution contains SO4 2- , the mixed slurry needs to simultaneously mix the reagent containing Ca 2+ ; when the chemical precipitation induction solution contains OH - , the slurry needs to simultaneously mix the reagent containing iron ions; wherein the iron ions refer to Fe 2+ and / or Fe 3+ .

[0008] Preferably, in step b, the distance D between the mixed slurry perfusion borehole and the mining boundary is determined according to the arc fracture width d of the key layer of the top boundary of the water flowing fracture zone at the mining boundary, D=(0.5~0.75)d, and the units of D and d are m.

[0009] Preferably, in step b, the mixed slurry filling drilling hole is constructed by vertical drilling to a depth of 10-15 m below the top boundary of the water flowing fractured zone, and a casing is used to protect the wall of the drilling hole from the surface to the top boundary of the water-bearing layer, and the following drilling section is a bare hole; when the strike size of the mining area exceeds the first set size, a mixed slurry filling drilling hole is arranged every first set size along the strike; when the inclination size of the mining area exceeds the first set size, a mixed slurry filling drilling hole is arranged every first set size along the inclination; the first set size is 150-200 m.

[0010] Preferably, in step b, the chemical precipitation induced solution filling drilling hole is not more than 10 m away from the mining boundary.

[0011] Preferably, in step b, the chemical precipitation induced solution filling drilling hole is not more than 10 m away from the mining boundary.

[0012] Preferably, in step b, the chemical precipitation induced solution filling drilling hole is constructed by vertical drilling; if the strike size of the mining area exceeds the second set size, a chemical precipitation induced solution filling drilling hole is arranged every second set size along the strike, and if the inclination size of the mining area exceeds the second set size, a chemical precipitation induced solution filling drilling hole is arranged every second set size along the inclination; the second set size is 300-400 m.

[0013] Preferably, in step b, the chemical precipitation induced solution filling drilling hole is constructed by horizontal directional drilling, and in the strike direction, the length of the horizontal section is the same as the strike length of the water flowing fractured zone communicating with the water-bearing layer region, and in the inclination direction, the length of the horizontal section is the same as the inclination length of the water flowing fractured zone communicating with the water-bearing layer region.

[0014] Preferably, in step c, the mixed slurry is prepared from one or more of fly ash, coal gangue powder, clay, and yellow mud and water; the particle size of the grouting material is not less than 200 mesh.

[0015] Preferably, in step c, when the mixed slurry is injected, the water-cement ratio is initially set to 5-10, and when the grouting pressure increases, the water-cement ratio is gradually increased to 20, and when the grouting pressure reaches 1.5-1.8 times the water head value corresponding to the depth of the mixed slurry filling drilling hole, the grouting is stopped.

[0016] Preferably, in step c, when the chemical precipitation induced solution is injected, a high-concentration low-flow method is used; the injection flow rate q is determined according to the strike length L of the water flowing fractured zone communicating with the water-bearing layer region and the underground water inflow Q of the corresponding mining area, q≤(50-70)Q / L, wherein the units of the injection flow rate q and the underground water inflow Q are m 3 / h, and the unit of the strike length L is m.

[0017] Preferably, it further comprises step d, during the perfusion process, periodically sampling and testing the water inrush from the underground mining area and the aquifer, and reducing the perfusion flow rate of the chemical precipitation inducing solution when the concentration of the chemical precipitation inducing solution is relatively large.

[0018] Key technical means and beneficial effects of the present application: Based on the development law of water-conducting fissures in overburden strata affected by mining and the loss law of aquifer water in the water-conducting fissures, the present application makes full use of the separation at the top interface of the key layer at the top boundary of the water-conducting fissure zone to diffuse the chemical precipitation inducing reagent, so that the mixed slurry injected in the water-conducting fissures can effectively converge and fully react with the mixed slurry. The iron and / or calcium chemical precipitate generated thereby can consolidate the particles of the grouting material together through adsorption and wrapping, promote the formation of chemical scale in the water-conducting fissures, effectively block the leakage channels of the mining aquifer, realize the ecological function repair and in-situ protection of the mining aquifer, and provide technical support for water resource protection and ecological repair in the mining area. The present application has low engineering quantity, strong practicability, can effectively reduce the leakage degree of the aquifer, and has low cost. BRIEF DESCRIPTION OF DRAWINGS

[0019] Figure 1 is a plan view of the repair method of the present application when the chemical precipitation inducing solution perfusion borehole is a vertical borehole.

[0020] Figure 2 is a sectional view of the repair method of the present application when the chemical precipitation inducing solution perfusion borehole is a vertical borehole.

[0021] Figure 3 is a plan view of the repair method of the present application when the chemical precipitation inducing solution perfusion borehole is a horizontal directional borehole.

[0022] Figure 4 is a sectional view of the repair method of the present application when the chemical precipitation inducing solution perfusion borehole is a horizontal directional borehole.

[0023] In the figure: 1-mixed slurry perfusion borehole; 2-chemical precipitation inducing solution perfusion borehole; 3-water-conducting fissure zone; 4-aquifer; 5-key layer at the top boundary of the water-conducting fissure zone; 6-cutting eye; 7-section coal pillar; 8-stopping line; 9-aquifer region communicated by the water-conducting fissures. DETAILED DESCRIPTION

[0024] The present application will be further illustrated below in conjunction with the drawings and specific embodiments, and it should be understood that these examples are only used to illustrate the present application and not to limit the scope of the present application. After reading the present application, those skilled in the art can make various equivalent modifications to the present application, which all fall within the scope defined by the claims attached hereto.

[0025] As Figures 1 to 4As shown, a certain coal mining area starts from the cut 6 along the strike to the stop line 8, and the inclination of the two sides is the section coal pillar 7. After the coal seam in the mining area is mined, the water-conducting fracture is generated in the overburden rock, and the area formed by all the water-conducting fractures is the water-conducting fracture zone 3. The water-conducting fracture zone is a technical term known in the art, and will not be described here. Since the water-conducting fracture communicates with the aquifer 4 (the water-conducting fracture zone top boundary key layer 5 is located in the aquifer 4), the water in the aquifer 4 continuously flows into the goaf, thereby causing the water level of the aquifer 4 to drop and the surface ecological water to be difficult to obtain. To this end, the present application proposes a mining aquifer repair method for artificially inducing chemical scaling of water-conducting fractures to solve the above problems, which specifically includes the following steps.

[0026] a. Detect the development of the water-conducting fracture in the coal mining area, and delineate the water-conducting fracture communication aquifer area 9. In the embodiment, the water-conducting fracture communication aquifer area 9 is located in the rear section of the coal mining area, i.e. close to the stop line 8 section.

[0027] b. Construct the mixed slurry injection borehole 1 and the chemical precipitation induction solution injection borehole 2 in the water-conducting fracture communication aquifer area 9; the mixed slurry injection borehole 1 is arranged inside the mining boundary and in the separation fracture development range in the water-conducting fracture zone 3, and is deep into the water-conducting fracture zone 3 by a set depth, so as to improve the planar diffusion range of the mixed slurry in the water-conducting fracture zone 3; the distance D between the mixed slurry injection borehole 1 and the mining boundary is determined according to the arc fracture width d of the water-conducting fracture zone top boundary key layer 5 at the mining boundary, D=(0.5~0.75)d, and the units of D and d are m; the mixed slurry injection borehole 1 is constructed by using the vertical drilling method, and in the embodiment, it is constructed to a depth of 10~15m below the top interface of the water-conducting fracture zone 3. The drilling section from the surface to the top interface of the water-conducting fracture zone 3 uses casing consolidation wall protection, and the following drilling section is a bare hole; when the strike size of the coal mining area exceeds the first set size, one mixed slurry injection borehole 1 is arranged every first set size along the strike; when the inclination size of the coal mining area exceeds the first set size, one mixed slurry injection borehole 1 is arranged every first set size along the inclination; and the first set size is 150~200m.

[0028] The chemical precipitation induced solution perfusion borehole 2 is arranged inside or outside the mining boundary and is located near the mining boundary, and the final hole horizon is located at the top interface of the key layer 5 of the top boundary of the water flowing fractured zone, between the V-shaped tension fracture line near the mining boundary and the overburden rock support pressure peak; the chemical precipitation induced solution perfusion borehole 2 is not more than 10 m away from the mining boundary; the surface to the top interface of the aquifer 4 drilling section of the chemical precipitation induced solution perfusion borehole 2 is protected by casing consolidation, and the following drilling section is a bare hole, so that the chemical precipitation induced solution is dissolved in the water in the aquifer 4; because the top interface of the key layer 5 of the top boundary of the water flowing fractured zone will generate a separation (extremely small thickness) with a plane range similar to the size of the water flowing fractured zone communicating aquifer region 9, the chemical precipitation induced solution will quickly and widely spread in the aquifer 4, and then flow into the downward water flowing fractured zone with the water in the aquifer 4, so that the plane range of the chemical precipitation induced solution and the mixed slurry can be increased; in addition, because the mixed slurry is only injected into the water flowing fractured zone, the water in the aquifer 4 will not be polluted.

[0029] As shown in Figure 1 , Figure 2 , the chemical precipitation induced solution perfusion borehole 2 is constructed by using a vertical drilling method, if the strike size of the coal mining area exceeds a second set size, one chemical precipitation induced solution perfusion borehole 2 is arranged every second set size along the strike, and if the inclination size of the coal mining area exceeds the second set size, one chemical precipitation induced solution perfusion borehole 2 is arranged every second set size along the inclination; the second set size is 300-400 m.

[0030] As shown in Figure 3 , Figure 4 , the chemical precipitation induced solution perfusion borehole 2 is constructed by using a horizontal directional drilling method, in the strike direction, the length of the horizontal section is the same as the strike length of the circled water flowing fractured zone communicating aquifer region 9; in the inclination direction, the length of the horizontal section is the same as the inclination length of the circled water flowing fractured zone communicating aquifer region 9.

[0031] c. The mixed slurry is injected into the water flowing fractured zone through the mixed slurry perfusion borehole 1, and the chemical precipitation induced solution is injected into the aquifer 4 through the chemical precipitation induced solution perfusion borehole 2; the mixed slurry is prepared by mixing traditional inert grouting materials such as fly ash, coal gangue powder, clay or yellow mud with water according to a certain water-cement ratio, the grouting material is one or more of them, and the particle size of the grouting material is not less than 200 mesh; a certain amount of reagent containing Ca 2+ and / or iron ions needs to be mixed in the mixed slurry; when the mixed slurry is injected, the water-cement ratio is initially set to 5-10, and when the grouting pressure increases, the water-cement ratio is gradually increased to 20, and when the grouting pressure reaches 1.5-1.8 times the water head value of the mixed slurry perfusion borehole 1 corresponding to the hole depth, the grouting is stopped.

[0032] The chemical precipitation inducing solution is prepared by mixing a reagent containing CO3 2- , SO4 2- , OH - with water in a certain concentration; when the chemical precipitation inducing solution contains CO3 2- , a certain amount of reagent containing Ca 2+ and / or iron ions should be added into the mixed slurry; when the chemical precipitation inducing solution contains SO4 2- , a certain amount of reagent containing Ca 2+ should be added into the mixed slurry; when the chemical precipitation inducing solution contains OH - , a certain amount of reagent containing iron ions should be added into the mixed slurry. In the present application, the iron ions refer to Fe 2+ and / or Fe 3+ , same as the prior art.

[0033] When the chemical precipitation inducing solution is injected, a high-concentration low-flow method is adopted; the injection flow rate q is determined according to the strike length L of the water-bearing layer region 9 and the underground water inflow Q of the coal mining region, q≤(50~70)Q / L, so as to improve the degree of sufficient dissolution of the chemical precipitation inducing solution in the underground water; wherein the units of the injection flow rate q and the underground water inflow Q are m 3 / h, and the unit of the strike length L is m.

[0034] d. During the injection process, the underground water inflow of the coal mining region and the water in the water-bearing layer 4 are periodically sampled and tested; when the concentration of the chemical precipitation inducing solution is high, the injection flow rate of the chemical precipitation inducing solution is reduced.

[0035] The above only describes the preferred embodiments of the present application, and it should be noted that for those skilled in the art, without departing from the principles of the present application, a number of improvements and refinements can be made, and these improvements and refinements should also be considered as the protection scope of the present application.

Claims

1. A method of water-conducting fracture artificial induction chemical scale formation mining aquifer remediation, characterized in that, The method comprises the following steps: a. detecting the water-conducting fissure development in the coal mining area, and delineating the water-conducting fissure communication aquifer area; b. constructing mixed slurry injection boreholes and chemical precipitation induced solution injection boreholes in the water-conducting fissure communication aquifer area; the mixed slurry injection boreholes are arranged inside the mining boundary and in the separation fissure development range in the water-conducting fissure zone, and are deep into the water-conducting fissure zone by a set depth; the chemical precipitation induced solution injection boreholes are arranged inside or outside the mining boundary and near the mining boundary, and the terminal hole layer is located at the top interface of the key layer of the top boundary of the water-conducting fissure zone; the distance D between the mixed slurry injection borehole and the mining boundary is determined according to the arc fracture width d of the key layer of the top boundary of the water-conducting fissure zone at the mining boundary, and D=(0.5~0.75)d, the units of D and d are m; the mixed slurry injection borehole is constructed by vertical drilling to a depth of 10~15m below the top boundary of the water-conducting fissure zone, the drilling section from the ground surface to the top interface of the water-conducting fissure zone is protected by casing consolidation, and the following drilling section is a bare hole; when the strike size of the coal mining area exceeds a first set size, one mixed slurry injection borehole is arranged every first set size along the strike; when the inclination size of the coal mining area exceeds the first set size, one mixed slurry injection borehole is arranged every first set size along the inclination; the first set size is 150~200m; the chemical precipitation induced solution injection borehole is not more than 10m away from the mining boundary; the drilling section from the ground surface to the top interface of the aquifer of the chemical precipitation induced solution injection borehole is protected by casing consolidation, and the following drilling section is a bare hole; The chemical precipitation induced solution injection borehole is constructed by vertical drilling; if the strike size of the coal mining area exceeds a second set size, one chemical precipitation induced solution injection borehole is arranged every second set size along the strike; if the inclination size of the coal mining area exceeds the second set size, one chemical precipitation induced solution injection borehole is arranged every second set size along the inclination; the second set size is 300~400m; or, the chemical precipitation induced solution injection borehole is constructed by horizontal directional drilling; in the strike direction, the length of the horizontal section is the same as the strike length of the delineated water-conducting fissure communication aquifer area; in the inclination direction, the length of the horizontal section is the same as the inclination length of the delineated water-conducting fissure communication aquifer area. c. The mixed slurry is injected into the water fissure through the mixed slurry filling drilling, and the chemical precipitation induced solution is injected into the aquifer through the chemical precipitation induced solution filling drilling. The chemical precipitation induced solution is prepared by mixing one or more of CO3 2- , SO4 2- , OH - with water; the mixed slurry is prepared by mixing inert grouting material with water; when the chemical precipitation induced solution contains CO3 2- , the mixed slurry needs to be mixed with a reagent containing Ca 2+ and / or iron ions; when the chemical precipitation induced solution contains SO4 2- , the mixed slurry needs to be mixed with a reagent containing Ca 2+ ; when the chemical precipitation induced solution contains OH - , the mixed slurry needs to be mixed with a reagent containing iron ions; wherein the iron ions refer to Fe 2+ and / or Fe 3+ .

2. The waterfissure-inducing, chemical scale-forming, mining-aquifer remediation method of claim 1, wherein, In step c, the mixed slurry is prepared from one or more of fly ash, coal gangue powder, clay, and yellow mud and water; the particle size of the grouting material is not less than 200 mesh.

3. The waterfissure-inducing, chemical scale-forming, mining-aquifer remediation method of claim 2, wherein, In step c, when the mixed slurry is injected, the water-cement ratio is initially set to 5~10, the water-cement ratio is gradually increased to 20 when the grouting pressure increases, and the grouting is stopped when the grouting pressure reaches 1.5~1.8 times the water head value corresponding to the hole depth of the mixed slurry injection borehole.

4. The waterfissure-inducing, chemical scale-forming, mining-aquifer remediation method of claim 1, wherein, In step c, when perfusing the chemical precipitation induction solution, a high concentration and low flow rate mode is adopted; the perfusion flow rate q is determined according to the strike length L of the water conducting fracture communicating the aquifer region and the underground water inflow Q of the corresponding coal mining region, q≤(50~70)Q / L, wherein the units of the perfusion flow rate q and the underground water inflow Q are m 3 / h, and the unit of the strike length L is m.

5. The waterfissure-inducing, chemical scale-forming, mining-aquifer remediation method of claim 1, wherein, Step d is also included, in which the underground water inrush in the coal mining area and the water in the aquifer are periodically sampled and tested during the injection process, and the injection flow of the chemical precipitation induced solution is reduced when the concentration of the chemical precipitation induced solution is relatively high.

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