Coal mining ecological diving protection method using nano bubbles

Abstract

The application discloses a kind of coal mining ecological diving protection methods using nano bubble, comprising the following steps: step one: using water-conducting fracture zone prediction method, the development height H of water-conducting fracture zone is predicted;Step two: calculate the development depth h of surface ground fissure;Step three: determine the influence type of coal mining on groundwater, including groundwater rising type, groundwater descending type, groundwater disappearance type;Step four: according to the judgment result of step three, corresponding nano bubble technology is taken for different influence types;Step five: after coal mining adjacent working face, repeat step one to step four, until groundwater aquifer artificial or natural repair stops above steps, realize coal mining ecological environment protection.The application has wider application range, can make full use of atmospheric precipitation, reduce artificial irrigation, environment is relatively friendly, and can also reduce the additional labor intensity of underground special mining operation.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of environmental engineering and mining engineering, and particularly relates to a coal mining ecological groundwater protection method using nano bubbles. BACKGROUND

[0002] The main area of coal mining in China is concentrated in the ecologically fragile area, and the superficial ecology of the ecologically fragile area is controlled by ecological groundwater, so the ecological groundwater protection in the coal mining area is of great significance. The existing ecological water protection technologies mainly include reducing the coal mining height, filling mining, water storage irrigation in the goaf, artificial irrigation and setting a protective coal pillar, but the following problems exist.

[0003] 1) The methods such as reducing the coal mining height damage the coal resources, causing resource waste;

[0004] 2) The mining cost of filling mining is greatly increased, and the speed of coal mining is seriously affected, increasing the underground labor intensity;

[0005] 3) The water storage irrigation in the goaf has a potential water hazard threat to the underground coal mining, which is not safe;

[0006] 4) The artificial irrigation in the coal mining crack area is a waste of water resources, which is not environmentally friendly;

[0007] 5) The magnetization control capillary water guide lifting height is suitable for clay such as loess, and the application range is relatively limited. SUMMARY

[0008] The purpose of the present application is to provide a coal mining ecological groundwater protection method using nano bubbles, which has a wider application range, can fully utilize atmospheric precipitation, reduce artificial irrigation, is relatively environmentally friendly, and can reduce the additional labor intensity of special mining operations underground.

[0009] To achieve the above purpose, the present application provides a coal mining ecological groundwater protection method using nano bubbles, comprising the following steps:

[0010] Step 1: predicting the development height H of the water-conducting fractured zone by using the water-conducting fractured zone prediction method;

[0011] Step 2: calculating the development depth h of the surface ground fissure;

[0012] Step 3: judging the influence type of coal mining on groundwater, including groundwater rising type, groundwater falling type and groundwater disappearing type;

[0013] Step 4: according to the judgment result of step 3, corresponding nano bubble technology is taken for different influence types;

[0014] Step five: repeat step one to step four after the adjacent working face of coal mining, until the artificial or natural restoration of the phreatic aquifer stops, and the above steps are implemented to realize the ecological environment protection of coal mining.

[0015] As a further scheme of the present application: in step one, In the formula, m is the mining thickness of the coal seam, which is obtained through a borehole column chart; and n is the number of coal mining sub-layers, which is obtained through coal mining design.

[0016] As a further scheme of the present application: in step two, In the formula, c is the cohesion of the surface soil, which is obtained through soil mechanics experiment; is the internal friction angle of the surface soil, which is obtained through soil mechanics experiment; and γ is the bulk density of the surface soil, which is obtained through soil mechanics experiment.

[0017] As a further scheme of the present application: in step three, the influence type is determined in combination with the relationship between the distance D between the phreatic underling aquiclude and the mining coal seam, the thickness M of the aquiclude and H, and the specific determination is as follows:

[0018] 1) when H≤D, it is determined as the phreatic water rising type, the rising height W=m×α, m is the mining thickness of the coal seam, and α is the subsidence coefficient;

[0019] 2) when D<H<D+M, it is determined as the phreatic water descending type, the phreatic water descending height A=N×(H-D) / M, N is the height of the phreatic water surface from the phreatic water bottom plate before coal mining;

[0020] 3) when H≥D+M, it is determined as the phreatic water disappearing type.

[0021] As a further scheme of the present application: in step four, corresponding nano-bubble technology is taken for different influence types, and the specific determination is as follows:

[0022] 1) the phreatic water rising type:

[0023] a borehole is implemented from the ground to the underground, the borehole depth is greater than h, a nano-bubble generating device is buried in the borehole, nano-oxygen is generated in the nano-bubble generating device, the oxygen content X2 increased by the explosion is W / N×X1, wherein X1 is the oxygen content of the phreatic water before coal mining, which is obtained through sampling test; the interval of the adjacent boreholes is K×I×T, wherein K is the permeability coefficient after the phreatic water coal mining, which is obtained through pumping experiment; I is the hydraulic gradient after the coal mining, which is obtained through observation calculation of the adjacent boreholes; T is the stable time of the nano-bubble, which is 12-36 hours; the time interval of the nano-bubble generating device is a×T, a is the bubble stability coefficient, which is 0.6-0.9;

[0024] 2) the phreatic water descending type:

[0025] If B-(NA) ≤ 3 meters, nanobubble technology is implemented according to the underwater ascent type. If B-(NA) > 3 meters, the following method is adopted: drilling is carried out from the ground to the underground, with a drilling depth greater than h. A nanobubble generator is buried in the drill hole, and nano-hydrogen is aerated in the nanobubble generator until the underwater surface is buried at a depth of 1.5 to 3 meters after coal mining. The nanobubble generator is operated at intervals after the underwater surface descends to 3 meters. The spacing between adjacent drill holes is consistent with the ascent type. Where N is the height of the underwater surface from the underwater floor before coal mining, which is obtained through the drill columnar section; A is the underwater descent height, which is obtained from step three; B is the height of the underwater floor from the ground before coal mining, which is obtained through the drill columnar section.

[0026] 3) Disappearance by diving:

[0027] Drilling is carried out at the surface coal mining fractures to a depth of 1.5 to 3 meters. A clay suspension is injected into the borehole, with a clay-to-water mass ratio of 1:10 to 20. The interval between injections of the suspension is b×T, where b is the bubble stability coefficient of the suspension, which is 0.9 to 1.0. The injection ends when the injection pressure is greater than 0.1 MPa. The distance between adjacent boreholes is 0.8 to 1.2 times E, where E is the coal mining pressure step distance, which is obtained through coal mine pressure monitoring.

[0028] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0029] 1) It does not require extensive changes to mining engineering and is simple to implement;

[0030] 2) It is not only applicable to cohesive soils such as loess, but also to sandy soils, making it more widely applicable;

[0031] 3) Make full use of atmospheric precipitation, reduce artificial irrigation, and be relatively environmentally friendly;

[0032] 4) It did not cause a large-scale accumulation of water in the well, resulting in better safety;

[0033] 5) It does not affect normal coal mining operations and reduces the extra labor intensity of special underground mining operations. Attached Figure Description

[0034] Figure 1 This is a flowchart of the coal mining ecological groundwater protection method using nanobubbles according to the present invention. Detailed Implementation

[0035] The present invention will be further illustrated by the following examples.

[0036] like Figure 1 As shown, a method for protecting coal mining ecological groundwater using nanobubbles includes the following steps:

[0037] Step one: predict the height H of the water flowing fractured zone by using the water flowing fractured zone prediction method;

[0038] Specifically, in step one: In the formula, m is the thickness of the coal seam, which is obtained through the borehole column chart; n is the number of coal mining sub-levels, which is obtained through coal mining design;

[0039] Step two: calculate the development depth h of the surface ground fissure;

[0040] Specifically, in step two: In the formula, c is the cohesion of the surface soil, which is obtained through soil mechanics experiment; is the internal friction angle of the surface soil, which is obtained through soil mechanics experiment; γ is the bulk density of the surface soil, which is obtained through soil mechanics experiment;

[0041] Step three: determine the influence type of coal mining on the phreatic water, including the phreatic water rising type, the phreatic water descending type, and the phreatic water disappearing type;

[0042] Specifically, in step three, the influence type is determined in combination with the distance D between the phreatic water underlying aquiclude and the mined coal seam, the relationship between the aquiclude thickness M and H, and the specific steps are as follows:

[0043] 1) When H≤D, it is determined as the phreatic water rising type, and the rising height W=m×α, m is the thickness of the coal seam, and α is the subsidence coefficient;

[0044] 2) When D<H<D+M, it is determined as the phreatic water descending type, and the phreatic water descending height A=N×(H-D) / M, N is the height of the phreatic water surface from the phreatic water bottom plate before mining;

[0045] 3) When H≥D+M, it is determined as the phreatic water disappearing type;

[0046] Step four: according to the judgment result of step three, corresponding nano-bubble technology is taken for different influence types;

[0047] Specifically, in step four, corresponding nano-bubble technology is taken for different influence types, and the specific steps are as follows:

[0048] 1) Phreatic water rising type:

[0049] By drilling a hole to the ground, the hole depth is greater than h, and a nanobubble generating device is buried in the hole, nanometer oxygen is generated in the nanobubble generating device, and the oxygen content X2 of the explosion is increased, X2=W / N*X1, wherein X1 is the oxygen content of the diving before coal mining, which is obtained by sampling test; the interval of adjacent drill holes is K*I*T, wherein K is the permeability coefficient after diving coal mining, which is obtained by pumping test; I is the hydraulic gradient after coal mining, which is obtained by observing and calculating adjacent drill holes; T is the nanobubble stable time, which is 12-36 hours; the time interval of the nanobubble generating device is a*T, and a is the bubble stability coefficient, which is 0.6-0.9;

[0050] 2) Diving descending type:

[0051] If B-(N-A) is less than or equal to 3 meters, the nanobubble technology is implemented according to the diving ascending type, if B-(N-A) is greater than 3 meters, the following method is adopted: drilling a hole to the ground, the hole depth is greater than h, and a nanobubble generating device is buried in the hole, nanometer hydrogen is generated in the nanobubble generating device, and the nanobubble generating device is operated after the diving surface drops to 3 meters, and the interval of adjacent drill holes is consistent with the ascending type; wherein N is the height of the diving surface from the diving floor before coal mining, which is obtained by drilling columnar diagram; A is the diving descending height, which is obtained by step three; B is the height of the diving floor from the ground before coal mining, which is obtained by drilling columnar diagram;

[0052] 3) Diving disappearance type:

[0053] Drilling a hole to the ground at the coal mining crack, the hole depth is 1.5-3 meters, and clay suspension liquid is injected into the hole, the mass ratio of clay and water in the suspension liquid is 1:10-20, the interval of suspension liquid injection is b*T, b is the suspension bubble stability coefficient and is 0.9-1.0, the injection end standard is that the injection pressure is greater than 0.1MPa, and the interval of adjacent drill holes is 0.8-1.2 times of E, E is the coal mining pressure step distance, which is obtained by coal mine pressure observation;

[0054] Step five: after the coal mining adjacent working face, steps one to four are repeated, until the diving aquifer is artificially or naturally repaired, and the above steps are realized to realize the ecological environment protection of coal mining.

[0055] The implementation principle of the application is that the nanobubble has three main characteristics, which correspond to three types of ecological diving protection working conditions:

[0056] First, the nanobubble has good stability and adsorption. Compared with millimeter and micron bubbles, the nanobubble stability is improved by more than 4 orders of magnitude, so it always maintains bubble stability during migration, and can be stored in the coal mining fracture soil for a long time by the capillary guide and adsorption of clay, and can provide water resources for vegetation after the bubble explosion, and is not easy to cause large-scale loss, so as to improve the utilization rate of water resources, and is particularly suitable for the type of disappearing groundwater.

[0057] Second, the nanobubble can greatly reduce the density of water-gas mixture after adding hydrogen and other light gases, thereby effectively lifting the water level, and the lifted water level can effectively offset the problem of the decline of the phreatic water level caused by coal mining, so as to protect the ecological water level with a depth of 1.5-3 meters as the target, and is particularly suitable for the case where the buried depth is greater than the ecological suitable phreatic water level in the type of descending groundwater.

[0058] Third, the nanobubble can release a large amount of hydroxyl radicals and oxygen when it explodes, which can provide oxygen for the vegetation submerged by water and kill harmful bacteria, and is particularly suitable for the type of ascending groundwater.

[0059] In specific implementation:

[0060] The ecological environment of a certain coal mine is fragile, and the decline of the phreatic water level caused by coal mining has affected the local ecological environment. In the past, the method of reducing the coal mining height was used, which caused a large amount of waste of coal resources. Therefore, the present technology is used to protect the phreatic water as much as possible on the basis of mining coal resources, and the specific implementation is as follows:

[0061] Step one: using the water-conducting fracture zone prediction method to predict the development height H of the water-conducting fracture zone;

[0062] In the formula, m=4 meters, n=1, and at this time H=61.44 meters;

[0063] Step two: calculating the development depth h of the surface ground fissure;

[0064] In the formula, c=69 kPa, which is the cohesion of the surface soil, obtained through soil mechanics experiment; is the internal friction angle of the surface soil, obtained through soil mechanics experiment; and γ=17.0 kN / m3 is the unit weight of the surface soil, obtained through soil mechanics experiment. At this time, h=14.32 meters;

[0065] Step three: determining the influence type of coal mining on the phreatic water;

[0066] Combined with the distance D=44.69 meters between the phreatic water underlying aquiclude and the mined coal seam, the thickness M=40.66 meters of the aquiclude, and the relationship with H, it is determined to be the type of descending groundwater:

[0067] When D=44.69<H=61.44<D+M=85.35, it is determined as diving type, diving height A=N x (H-D) / M=16 x 16.75 / 40.66=6.59 meters, N=16 meters, the height of the water table before mining from the water table floor;

[0068] Step four: according to the judgment result of step three, take the corresponding nano bubble accumulated water;

[0069] Since B-(N-A)=18-9.41=8.59>3 meters, the following method is adopted: drilling from the ground to the underground, the drilling depth is 15 meters, the nano bubble generating device is buried in the drilling, the nano hydrogen gas is aerated in the device, the aeration is carried out until the water table after mining is 2 meters deep from the ground, the time interval of the operation of the nano generating device is after the water table drops to 3 meters, the spacing of adjacent drillings is consistent with the rising type; wherein N=16 meters, the height of the water table before mining from the water table floor, obtained by drilling columnar diagram; A=6.59 meters, the diving height, obtained by step three; B=18 meters, the height of the water table floor from the ground, obtained by drilling columnar diagram;

[0070] Step five: repeat steps 1-4 after coal mining in adjacent working face, until the artificial restoration of the water table is stopped, the above steps are implemented to realize the ecological environment protection of coal mining.

[0071] Since it is not necessary to reduce coal mining, about 400,000 tons of coal resources are mined in each working face, at the same time, the local ecological environment is protected, and the contradiction between coal mining and ecological environment protection is effectively solved.

Claims

1. A coal mining ecological diving protection method using nanobubbles, characterized by, The method comprises the following steps: Step 1: predicting the height H of the water-conducting fracture zone by using a water-conducting fracture zone prediction method; Step 2: calculating the development depth h of the surface ground fissure; Step 3: judging the influence type of coal mining on the phreatic water, including the phreatic water rising type, the phreatic water descending type and the phreatic water disappearing type; The influence type is determined in combination with the distance D between the phreatic water underlying aquiclude and the mined coal seam, the thickness M of the aquiclude and the relationship between H, and the specific determination is as follows: 1) when H≤D, it is determined as the phreatic water rising type, the rising height W = m x a, m is the thickness of the coal seam mining, and a is the subsidence coefficient; 2) when D<H<D+M, it is determined as the phreatic water descending type, the phreatic water descending height A = N x (H-D) / M, N is the height of the phreatic water surface from the phreatic water bottom plate before mining; 3) when H≥D+M, it is determined as the phreatic water disappearing type; Step 4: according to the judgment result of step 3, corresponding nano-bubble technology is taken for different influence types; 1) the phreatic water rising type: Drilling is implemented from the ground to the underground, the drilling depth is greater than h, the nano-bubble generating device is buried in the drilling, nano-oxygen gas is generated in the nano-bubble generating device, the oxygen content X2 increased by the gas is W / N x X1, wherein X1 is the oxygen content of the phreatic water before mining, which is obtained by sampling test; the interval of adjacent drillings is K x I x T, wherein K is the permeability coefficient after the phreatic water mining, which is obtained by pumping test; I is the hydraulic gradient after mining, which is obtained by observing and calculating adjacent drillings; T is the nano-bubble stable time, which is taken as 12-36 hours; the time interval of the nano-bubble generating device is a x T, a is the bubble stability coefficient, taken as 0.6-0.9; 2) the phreatic water descending type: If B-(N-A)≤3 meters, the nano-bubble technology is implemented according to the phreatic water rising type, if B-(N-A)>3 meters, the following method is adopted: drilling is implemented from the ground to the underground, the drilling depth is greater than h, the nano-bubble generating device is buried in the drilling, nano-hydrogen gas is generated in the nano-bubble generating device, the gas is exposed until the phreatic water surface after mining is buried at a depth of 1.5-3 meters from the ground; the time interval of the nano-bubble generating device is developed after the phreatic water surface drops to 3 meters, the interval of adjacent drillings is consistent with the rising type; wherein N is the height of the phreatic water surface from the phreatic water bottom plate before mining, which is obtained by drilling columnar chart; A is the phreatic water descending height, which is obtained by step 3; B is the height of the phreatic water bottom plate from the ground before mining, which is obtained by drilling columnar chart; 3) the phreatic water disappearing type: Drilling is implemented from the ground to the underground at the ground mining fissure, the drilling depth is 1.5-3 meters, clay suspension liquid is injected into the drilling, the mass ratio of clay and water in the suspension liquid is taken as 1:10-20, the interval of suspension liquid injection is b x T, b is the suspension bubble stability coefficient, taken as 0.9-1.0, the injection end standard is that the injection pressure is greater than 0.1 MPa, the interval of adjacent drillings is 0.8-1.2 times of E, E is the mining pressure step distance, which is obtained by observing the mining mine pressure; Step 5: after the coal mining adjacent working face, steps 1-4 are repeated until the phreatic water aquifer is artificially or naturally repaired, the above steps are implemented to realize the ecological environment protection of coal mining.

2. The coal mining ecological diving protection method using nano bubbles according to claim 1, characterized in that, In step one: In the formula, m is the mining thickness of the coal seam, which is obtained through a borehole column chart; and n is the number of coal mining sections, which is obtained through coal mining design.

3. The coal mining ecological diving protection method using nano bubbles according to claim 1, characterized in that, In step two: , in which c is the cohesion of the surface soil, obtained through soil mechanics experiments; φ is the internal friction angle of the surface soil, obtained through soil mechanics experiments; and γ is the bulk density of the surface soil, obtained through soil mechanics experiments.

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