A roof pre-splitting device and its pre-splitting method

Abstract

The present invention provides a roof pre-splitting device and a pre-splitting method thereof, relating to the technical field of mineral mining, and aiming to solve the technical problems that the direction and range of roof pre-splitting and stable pressure cannot be effectively guaranteed. The roof pre-splitting method includes drilling at least two holes obliquely upward on the periphery of the roof pre-splitting position, each hole facing the roof pre-splitting position, there is a rock layer space between the bottoms of the holes, and the rock layer space has rock layer fissures; injecting calcium hydroxide solution with pressure into one hole and injecting carbon dioxide gas with pressure into one hole; the calcium hydroxide solution and the carbon dioxide gas react in the rock layer fissures to form solid calcium carbonate; under the combined action of the pressure of the calcium hydroxide solution, the pressure of the carbon dioxide gas and the solid-phase pressure of the calcium carbonate, the roof is pre-split directionally; the pressure of the solid calcium carbonate is the pressure in the vertical direction of the roof. The roof pre-splitting method of the present invention is used to control the directional caving of the roof in a mine.

Description

Technical Field

[0001] The present disclosure relates to the field of mineral mining, and particularly to a roof pre-splitting device and a pre-splitting method thereof. Background Art

[0002] During the process of mine exploitation, as the working face continuously advances, the controlled roof area in the stope gradually increases. The direct roof with a small thickness gradually collapses, and the hard main roof is exposed in a large area. Due to the action of the mine pressure, a natural pressure arch will be formed in the roof rock stratum of the working face, and the pressure on the coal wall will also change, resulting in the concentration of the roof pressure in the working face.

[0003] In the above situation, due to the pressure of the roof subsidence, roof fall is extremely likely to occur. Roof fall not only causes production delays but also is accompanied by accidents such as water inrush and gas outburst, resulting in casualties. Therefore, it is necessary to pre-split the roof with concentrated pressure.

[0004] Roof pre-splitting refers to pre-splitting the thick and hard roof above the coal seam in advance, destroying the integrity of the roof, artificially controlling the local roof caving, reducing the span and hanging area of the main roof cantilever beam, destroying the energy storage conditions of the roof, and preventing or reducing the occurrence of roof accidents.

[0005] In the prior art, mainly the method of pre-splitting by chemical explosive blasting is used for forced roof caving, the method of roof pre-splitting by water injection weakening, and the method of using dry ice to transform into CO2 to achieve roof pre-splitting. However, in the top coal caving working face of a high-gas mine, the use of gunpowder blasting technology is not allowed, and in an ordinary working face, the use of gunpowder blasting is also prone to personal injury accidents, with great limitations. At the same time, it will cause pollution and cannot meet the requirements of high efficiency, greenness, and environmental protection. For other pre-splitting technologies, it is difficult to ensure stable pressure and the expected effect of roof pre-splitting. Summary of the Invention

[0006] The purpose of the present invention is to provide a roof pre-splitting device and a pre-splitting method thereof to solve the technical problem in the prior art that the direction, range, and stable pressure of roof pre-splitting cannot be effectively guaranteed, so as to have the advantages of green environmental protection while ensuring the pre-splitting effect.

[0007] To achieve the above purpose, the present invention provides the following technical solutions:

[0008] An embodiment of the present invention provides a roof pre-splitting method for controlling the directional caving of the roof in a mine,

[0009] At least two drill holes are drilled obliquely upward on the periphery of the roof pre-splitting position, each of the drill holes faces the central position of the roof pre-splitting, and there is a rock stratum space between the bottoms of the drill holes, and the rock stratum space has rock stratum fissures;

[0010] Inject a calcium hydroxide solution with pressure into the at least one borehole and seal it, and inject carbon dioxide gas with pressure into the at least one borehole and seal it;

[0011] The calcium hydroxide solution and the carbon dioxide gas react in the rock fractures in the rock formation space to form solid calcium carbonate;

[0012] Under the combined action of the liquid pressure of the calcium hydroxide solution, the gas pressure of the carbon dioxide gas, and the solid pressure of the solid calcium carbonate, the roof is directionally pre-cracked;

[0013] The pressure of the solid calcium carbonate is the pressure in the vertical direction of the roof.

[0014] According to at least one embodiment of the present disclosure, each of the boreholes is evenly distributed circumferentially along the pre-cracking position of the roof.

[0015] According to at least one embodiment of the present disclosure, the inclination angle of each borehole relative to the horizontal plane is 15° to 45°.

[0016] According to at least one embodiment of the present disclosure, in the step of injecting a calcium hydroxide solution with pressure into the at least one borehole and sealing it, and injecting carbon dioxide gas with pressure into the at least one borehole and sealing it,

[0017] The calcium hydroxide solution and the carbon dioxide gas are respectively stored in storage tanks, and the calcium hydroxide solution and the carbon dioxide gas are respectively injected into the corresponding boreholes from the storage tanks through corresponding pressurizing devices.

[0018] Compared with the prior art, the roof pre-cracking method of the present invention injects a liquid-phase calcium hydroxide solution with a certain pressure and carbon dioxide gas with a certain pressure through a plurality of boreholes on the circumferential side of the roof pre-cracking position. Among them, the calcium hydroxide solution and the carbon dioxide gas also pass through the rock fractures in the rock formation space above the roof pre-cracking position, and then react to form solid calcium carbonate after mixing in the rock formation. The accumulation of a large amount of calcium carbonate will gradually occupy the original position of the roof rock formation, and the pressure on the roof will increase by forced extrusion. Under the action of the triple pressures of liquid pressure, gas pressure, and solid pressure, especially the pressure of solid calcium carbonate is basically the pressure in the vertical direction of the roof due to the influence of gravity, realizing the vertical occupation of the roof rock formation space and achieving the purpose of roof pre-cracking.

[0019] Compared with the separate water injection weakening in the prior art, the disadvantages of the large difference between the water injection weakening and the expected effect can be overcome. Compared with the separate air pressure pre - splitting, the solid calcium carbonate generated by the reactants in the present invention has small fluidity and can exert directional pressure on the roof, overcoming the deficiencies such as the difficulty in determining the specific pressure of the separate air pressure pre - splitting, insufficient air pressure, and the gas flowing around.

[0020] In the present invention, at least two drill holes are drilled obliquely upward on the periphery of the roof pre - splitting position, and each drill hole faces the central position of the roof pre - splitting. There is a rock formation space between the bottoms of the drill holes. The rock formation space has rock fractures, that is, the bottoms of the drill holes approach each other. A rock formation space is formed above the central position where the roof needs to be pre - split, that is, between the bottoms of each hole. Since the bottoms of each hole are close to each other, it is beneficial for the calcium hydroxide solution of the reactant and the carbon dioxide gas to flow through and fully contact and react to form solid calcium carbonate in the rock fractures of the rock formation space.

[0021] At the same time, compared with the prior art, the reactants and reaction products of the present invention are non - toxic and harmless products, and the whole pre - splitting method is environmentally friendly and efficient. And the whole construction process requires no excessive technical requirements and has a relatively high safety factor.

[0022] Another object of the present invention is to further provide a roof pre - splitting device for the above - mentioned roof pre - splitting method. The roof pre - splitting device includes a first storage tank, a second storage tank, a hydraulic grouting machine, and a booster pump;

[0023] The first storage tank is used to store the calcium hydroxide solution, and the second storage tank is used to store the carbon dioxide gas;

[0024] The hydraulic grouting machine is connected to the first storage tank, and the hydraulic grouting machine injects the calcium hydroxide solution into the corresponding drill hole through a pipeline;

[0025] The booster pump is connected to the second storage tank, and the booster pump injects the carbon dioxide gas into the corresponding drill hole through a pipeline.

[0026] According to at least one embodiment of the present disclosure, the roof pre - splitting device further includes a mine - used hole - sealing device, and the hole - sealing device is used to seal the drill holes into which the calcium hydroxide solution and the carbon dioxide gas are injected;

[0027] The roof pre - splitting device further includes an orifice stop valve, and the orifice stop valve is used for the penetration of the grouting or gas injection pipeline.

[0028] According to at least one embodiment of the present disclosure, the roof pre - splitting device further includes a controller. The hydraulic grouting pump and the booster pump are connected to the controller. The controller is used to control the flow rate and pressure of the hydraulic grouting pump, and the controller is also used to control the flow rate and pressure of the booster pump.

[0029] According to at least one embodiment of the present disclosure, the roof pre-cracking device further includes a pressure sensor, which is connected to the controller and is arranged at the central position of the roof pre-cracking.

[0030] The controller is configured to adjust the flow rates of the hydraulic grouting pump and the booster pump according to the pressure of the pressure sensor.

[0031] Compared with the prior art, the roof pre-cracking device of the present invention has the following advantages:

[0032] The roof pre-cracking device has the same advantages as the above-mentioned roof pre-cracking method compared with the prior art, which will not be elaborated here. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] The drawings illustrate exemplary embodiments of the present disclosure and, together with the description thereof, are used to explain the principles of the present disclosure. These drawings are included to provide a further understanding of the present disclosure and are included in this specification and form a part of this specification.

[0034] Figure 1 is a schematic diagram of multi-phase pressure amplification according to an embodiment of the present disclosure.

[0035] Figure 2 is a schematic diagram of the overall roof pre-cracking device according to an embodiment of the present disclosure.

[0036] Figure 3 is a schematic diagram of drilling according to an embodiment of the present disclosure.

[0037] Reference numerals: 1, roof; 2, rock formation space; 3, liquid injection pipe; 4, first storage tank; 5, gas injection pipe; 6, second storage tank; 7, liquid phase space; 8, solid phase space; 9, gas phase space; 10, liquid injection hole; 11, gas injection hole. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0038] The following further elaborates on the present disclosure in conjunction with the drawings and embodiments. It can be understood that the specific embodiments described herein are only used to explain the relevant content and do not limit the present disclosure. Additionally, it should be noted that for the sake of convenience of description, only the parts related to the present disclosure are shown in the drawings.

[0039] It should be noted that, without conflict, the embodiments in the present disclosure and the features in the embodiments can be combined with each other. The following will elaborate on the present disclosure in detail with reference to the drawings and embodiments.

[0040] In the prior art, roof pre - splitting generally adopts the water - injection weakening method for roof pre - splitting, but the expected effect is not stable. When using the air - pressure pre - splitting method, it is difficult to determine the specific pressure, and there is insufficient air pressure and gas leakage everywhere. When using chemical explosive blasting, it not only pollutes the environment but also easily causes personal injury and death accidents, especially it is prohibited in high - gas mines.

[0041] In order to overcome the drawbacks and deficiencies existing in the above - mentioned prior art, the core of the technical solution of the present invention lies in integrating multiple pressures. Through the gas - phase pressure, liquid - phase pressure and the solid - phase substances of the reactants of the gas phase and liquid phase, gradually occupy the original position of the roof rock formation. By means of forced extrusion, the pressure on the roof is increased. Through the coordinated cooperation of the introduced three - phase pressures, the roof undergoes chain - type instability, achieving the effect of roof pre - splitting.

[0042] Please refer to Figures 1 to 3 As shown, the roof pre - splitting method provided by the embodiment of the present invention is used to control the directional caving of the roof 1 in a mine. First, drill holes obliquely upward on the periphery of the roof pre - splitting position. At least two drill holes are required. As Figure 3 shown, each of the drill holes faces the roof pre - splitting position, that is, both drill holes face the rock - layer space 2, and there are rock - layer fissures in the rock - layer space 2, which can allow liquid - phase, gas - phase and solid - phase drugs to pass through. The orientations of the respective drill holes are inclined towards each other, which is beneficial to the flow and full reaction of the reactant liquid and gas. Exemplarily, liquid calcium hydroxide solution is injected from the liquid - injection hole 10, and gaseous carbon dioxide is injected from the gas - injection hole 11.

[0043] It can be understood that more drill holes, such as 3, 4, or 6 drill holes, can be set on the periphery of the roof pre - splitting position according to the actual situation, and are respectively used for grouting or gas injection.

[0044] Specifically, the liquid - phase Ca(OH)2 solution and the gas - phase CO2 gas are respectively introduced into the drill holes through pressurizing equipment, so that a certain air pressure and water pressure are generated on the roof, which can weaken the acting force between the roof rock formations to a certain extent, achieving the dual effects of water - injection weakening and air - pressure pre - splitting. Then, the reactants Ca(OH)2 and CO2 in the rock - layer space fissures react to produce calcium carbonate precipitate and accumulate. After a large amount of solid calcium carbonate is generated, it strongly occupies and squeezes the original position of the roof through the rock - layer fissures of the roof, and the roof is pre - split by means of occupying space and strong extrusion, achieving the effect of solid - pressure roof caving. Through the above two effects, the roof forms as Figure 1The acting forces shown, exemplarily form a downward liquid-phase pressure in the liquid-phase space 7, a downward gas-phase pressure in the gas-phase space 9, and a downward solid-phase pressure in the intermediate solid-phase space 8, thereby achieving the effect of increasing the pressure on the roof by occupying the space where the original roof rock formation is located, and achieving the effect of pre-cracking the roof. Through the pre-cracking method that integrates three-phase pressures, the present invention enables directional pre-cracking, has high stability, and causes no environmental pollution.

[0045] The principle of the solid-phase pressure in the roof pre-cracking method of the present invention is as follows:

[0046] Ca(OH)2 + CO2 → CaCO3↓ + H2O

[0047] In some embodiments, each drilling hole is evenly distributed along the circumferential direction of the roof pre-cracking position. Exemplarily, when there are only two drilling holes, the two drilling holes are arranged symmetrically along the vertical center line of the roof pre-cracking position to ensure precise control of the gas-phase, liquid-phase pressures and flow rates, thereby enabling the reactants to fully react. Specifically, the inclination angle of each drilling hole relative to the horizontal plane is 15° to 45°, further 20° to 40°, alternatively 25° to 35°, and optionally 30°. Within the above inclination angle range, it can not only ensure that the grout leaks from the opening due to its own gravity, but also ensure that the gas phase or liquid phase is injected into the rock formation space 2 to make it fully react and form a downward acting force, achieving the purpose of causing the roof to collapse directionally.

[0048] In the steps of injecting the liquid phase and the gas phase in the above roof pre-cracking method, as Figure 2 shown, the calcium hydroxide solution is stored in the first storage tank 4, and the carbon dioxide gas is stored in the second storage tank 6. The calcium hydroxide solution is injected into the injection hole 10 through a pressurizing device and an injection pipe 3, and the carbon dioxide gas is injected into the injection gas hole 11 through a corresponding pressurizing device and an injection gas pipe 5. Since the calcium hydroxide solution and the carbon dioxide gas are stored in different storage tanks respectively. When the coal seam is driven to the position where roof pre-cracking is required, the first storage tank 4 and the second storage tank 6 can be conveniently placed at the corresponding bottom plate positions of the roadway, and after drilling holes at the roof pre-cracking position, they are respectively injected into the fissures of the rock formation space through pipelines.

[0049] In some embodiments, the present invention also provides a roof pre-cracking device, as Figure 2 shown, the roof pre-cracking device includes a first storage tank 4, a second storage tank 6, a hydraulic grouting machine and a booster pump; the first storage tank 4 is used to store the calcium hydroxide solution, and the second storage tank 6 is used to store the carbon dioxide gas; the hydraulic grouting machine is connected to the first storage tank 4, and the hydraulic grouting machine injects the calcium hydroxide solution into the corresponding injection hole 10 through a pipeline; the booster pump is connected to the second storage tank 6, and the booster pump injects the carbon dioxide gas into the corresponding injection gas hole 11 through a pipeline.

[0050] In fact, the material of the first storage tank 4 does not react with the calcium hydroxide solution, and the material of the second storage tank 6 does not react with carbon dioxide gas. The calcium hydroxide solution is pressurized by a hydraulic grouting machine, so that the liquid phase entering the liquid injection hole 10 and the rock formation space 2 has a certain pressure; the carbon dioxide gas is pressurized by a booster pump, so that the gas phase entering the gas injection hole 11 and the rock formation space 2 has a certain pressure; at the same time, in the cracks of the rock formation space, due to a certain pressure, the reactants are more evenly mixed, and the rate of generating calcium carbonate solid phase substances is higher. Furthermore, a certain vertical solid phase strong extrusion can be provided, so that the construction time is shortened.

[0051] It can be understood that although not shown in the figure, the roof pre-splitting device further includes a mine sealing device, and the sealing device is used to seal the drill holes for injecting the calcium hydroxide solution and carbon dioxide gas; the roof pre-splitting device further includes an orifice stop valve, and the orifice stop valve is used for the penetration of the grouting or gas injection pipeline. The sealing device and the orifice stop valve are used to block the openings during the process of grouting or gas injection into the drill holes, preventing the calcium hydroxide solution and carbon dioxide gas from leaking from the drill holes.

[0052] Considering the pressure control of liquid injection and gas injection, and the generation rate of the solid calcium carbonate of the reactants during the roof pre-splitting process of the present invention. The roof pre-splitting device further includes a pressure sensor, the pressure sensor is connected to the controller, the pressure sensor is arranged at the central position of the roof pre-splitting, and the controller is used to adjust the flow rates of the hydraulic grouting pump and the booster pump according to the pressure of the pressure sensor. According to the information feedback of the pressure sensor on the pressure load at the roof pre-splitting position, the controller can control the injection amounts of the calcium hydroxide solution and carbon dioxide gas entering the cracks of the rock formation space at the pre-splitting roof position by adjusting the flow rates or pressures of the hydraulic grouting pump and the booster pump, so that a downward liquid phase pressure is formed in the liquid phase space 7, a downward gas phase pressure is formed in the gas phase space 9, and a downward solid phase pressure is formed in the solid phase space 8, and the three achieve an optimal synergistic effect, and the directivity and stability of the roof pre-splitting can be controlled, and then the collapse of the roof at the pre-splitting position can be completed efficiently and safely.

[0053] In the description of this specification, the description referring to terms such as "one embodiment / way", "some embodiments / ways", "example", "specific example", or "some examples" means that the specific features, structures, materials, or characteristics described in connection with the embodiment / way or example are included in at least one embodiment / way or example of this application. In this specification, the schematic expressions of the above terms do not necessarily refer to the same embodiment / way or example. Moreover, the specific features, structures, materials, or characteristics described can be combined in a suitable manner in any one or more embodiments / ways or examples. In addition, without contradiction, those skilled in the art can combine and combine the different embodiments / ways or examples described in this specification and the features of different embodiments / ways or examples.

[0054] In addition, the terms "first" and "second" are only used for descriptive purposes and cannot be understood as indicating or implying relative importance or implicitly specifying the quantity of the indicated technical features. Thus, the features defined with "first" and "second" can explicitly or implicitly include at least one of such features. In the description of this application, the meaning of "a plurality" is at least two, such as two, three, etc., unless otherwise clearly and specifically defined.

[0055] Those skilled in the art should understand that the above embodiments are only for clearly explaining the present disclosure and not for limiting the scope of the present disclosure. For those skilled in the art, other changes or modifications can be made on the basis of the above disclosure, and these changes or modifications are still within the scope of the present disclosure.

Claims

1. A roof pre-splitting method, characterized in that, For controlling the directional caving of the roof in a mine, the roof pre-splitting method includes: Drill at least two holes obliquely upward on the circumferential side of the roof pre-splitting position. Each of the holes faces the roof pre-splitting position, and there is a rock layer space between the bottoms of the holes. The rock layer space has rock layer fissures; Inject pressurized calcium hydroxide solution into at least one of the holes and seal it, and inject pressurized carbon dioxide gas into at least one other hole and seal it; The calcium hydroxide solution and the carbon dioxide gas react in the rock layer fissures in the rock layer space to form solid calcium carbonate; Under the combined action of the liquid phase pressure of the calcium hydroxide solution, the gas phase pressure of the carbon dioxide gas, and the solid phase pressure of the solid calcium carbonate, the roof is directionally pre-split; The pressure of the solid calcium carbonate is the pressure in the vertical direction of the roof.

2. The roof pre-splitting method according to claim 1, wherein, Each of the holes is evenly distributed along the circumference of the roof pre-splitting position.

3. The roof pre-splitting method according to claim 1, wherein The inclination angle of each hole relative to the horizontal plane is 15° to 45°.

4. The roof pre-splitting method according to claim 1, characterized in that, In the step of injecting pressurized calcium hydroxide solution into at least one of the holes and sealing it, and injecting pressurized carbon dioxide gas into at least one of the holes and sealing it, The calcium hydroxide solution and the carbon dioxide gas are respectively stored in storage tanks, and the calcium hydroxide solution and the carbon dioxide gas are respectively injected into the corresponding holes from the storage tanks through corresponding pressurizing devices.

5. A roof pre-splitting device, characterized in that, For the roof pre-splitting method according to any one of claims 1-4, the roof pre-splitting device includes a first storage tank, a second storage tank, a hydraulic grouting machine, and a booster pump; The first storage tank is used for storing calcium hydroxide solution, and the second storage tank is used for storing carbon dioxide gas; The hydraulic grouting machine is connected to the first storage tank, and the hydraulic grouting machine injects the calcium hydroxide solution into the corresponding holes through a pipeline; The booster pump is connected to the second storage tank, and the booster pump injects the carbon dioxide gas into the corresponding holes through a pipeline.

6. The roof pre-splitting device according to claim 5, characterized in that, The roof pre-splitting device further includes a mine sealing device, and the sealing device is used for sealing the holes into which the calcium hydroxide solution and the carbon dioxide gas are injected; The roof pre-splitting device further includes an orifice stop valve, and the orifice stop valve is used for the penetration of the grouting or gas injection pipeline.

7. The roof pre-splitting device according to claim 5, characterized in that, The roof pre-splitting device further includes a controller. The hydraulic grouting pump and the booster pump are connected to the controller. The controller is used for controlling the flow rate and pressure of the hydraulic grouting pump, and the controller is also used for controlling the flow rate and pressure of the booster pump.

8. The roof pre-splitting device according to claim 7, characterized in that, The roof pre-splitting device further includes a pressure sensor. The pressure sensor is connected to the controller. The pressure sensor is arranged at the central position of the roof pre-splitting. The controller is used for adjusting the flow rates of the hydraulic grouting pump and the booster pump according to the pressure of the pressure sensor.

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