A method for advanced treatment of spontaneous combustion of end slope coal in an open pit mine

Abstract

The application provides an open pit end slope coal spontaneous combustion advanced treatment method, and belongs to the technical field of coal safe mining, and comprises the following steps: determining a coal spontaneous combustion advanced treatment width B1 according to the stability coefficient of a slope in an initial state and a preset first step length; determining a coal spontaneous combustion treatment width B2 according to the stability coefficient of the slope in the initial state and a preset second step length; when the coal spontaneous combustion advanced treatment width B1 is greater than the coal spontaneous combustion treatment width B2, then the above steps are repeated, the coal spontaneous combustion treatment width B2 is gradually increased according to the preset second step length, and when the coal spontaneous combustion advanced treatment width B1 is less than or equal to the coal spontaneous combustion treatment width B2, the final coal spontaneous combustion treatment width is determined as the current coal spontaneous combustion treatment width B2. The application can effectively use the discarded materials to replace and fill the end slope coal seam with high spontaneous combustion tendency in advance, mine a large amount of end slope coal resources, save a large amount of discarded space, and facilitate construction conditions.

Description

Technical Field

[0001] This invention belongs to the field of coal safety mining technology, specifically relating to a method for proactively controlling spontaneous combustion of coal at the end of an open-pit mine. Background Technology

[0002] Open-pit coal mines are generally characterized by shallow burial, low degree of metamorphism, soft coal quality, high volatile matter content, and susceptibility to environmental factors. Under natural conditions, the coal body is extremely prone to breakage and oxidation, exhibiting a high tendency for spontaneous combustion. Furthermore, the end faces of open-pit coal mines are characterized by long periods of coal exposure and ample oxygen supply, making them highly susceptible to spontaneous combustion due to oxidation. This leads to significant safety issues, economic losses, substantial coal resource losses, severe environmental pollution from the generated toxic and harmful gases, and even triggers serious geological disasters such as slope instability, severely threatening safe production activities in the mine.

[0003] Invention application CN105863713A discloses a method for preventing spontaneous combustion of coal seams in open-pit mines. This method mainly involves cleaning up loose coal, adding chemical inhibitors for spontaneous combustion of coal, and layering and compacting the covering material to isolate oxygen. This method effectively isolates oxygen, but requires the addition of a large amount of chemical inhibitors. The covering material is easily affected by environmental factors, resulting in cracks or peeling, which allows the coal seam to come into contact with oxygen.

[0004] Invention application CN121203435A discloses a coal-based composite oxygen-barrier spraying material and its preparation method. The method is a spraying material prepared using coal slime and sodium silicate. By forming an oxygen-barrier layer on the surface of the coal body, it can prevent spontaneous combustion of coal. However, the preparation of this spraying material is complicated, and open-pit mines are easily affected by engineering disturbances. The oxygen-barrier layer is prone to large-area through cracks, and the flame-retardant effect is difficult to last.

[0005] Invention application CN121090756A discloses a method for determining the evolution process of spontaneous combustion of coal at the end of an open-pit mine. This method reveals that after spontaneous combustion of coal, the rock mass will generate a large number of fissures that provide pathways for oxygen by updating the porosity and permeability parameters of the curved subsidence zone, fracture zone and collapse zone in the combustion zone.

[0006] In summary, existing technologies mostly focus on passive control after coal spontaneous combustion occurs or using chemical spraying. However, these technologies pose extremely high risks to workers performing control operations in the post-combustion environment. Furthermore, they do not consider using waste materials to replace coal seams with a high tendency for spontaneous combustion, while ensuring the safety of the open-pit coal mine's end walls. This would not achieve efficient, economical, environmentally friendly, and safe proactive control. Therefore, there is an urgent need to find a proactive control method for coal spontaneous combustion in open-pit mines, providing corresponding technical support for this proactive approach. Summary of the Invention

[0007] To address the shortcomings of existing technologies, this application proposes a method for proactively controlling spontaneous combustion of coal at the end of open-pit mines, comprising:

[0008] Step S1: Obtain the geometric parameters of the end slope;

[0009] Step S2: Obtain the physical and mechanical parameters of the rock and soil mass and the waste materials in the mining area;

[0010] Step S3: Based on the geometric and physical parameters, establish a two-dimensional end slope model and use the two-dimensional rigid body limit equilibrium method to calculate the stability coefficient of the two-dimensional end slope model in the initial state.

[0011] Step S4: Based on the stability coefficient of the slope in the initial state and the preset first step length, determine the coal spontaneous combustion advance treatment width B1, whereby the coal spontaneous combustion advance treatment width B1 is the maximum cumulative horizontal width of the end coal seam that can be mined inward.

[0012] Step S5: Determine the coal spontaneous combustion treatment width B2 based on the slope stability coefficient in the initial state and the preset second step length. The coal spontaneous combustion treatment width B2 is the cumulative horizontal width that needs to be replaced with waste material after the pre-treatment width B1 for coal spontaneous combustion in the end coal seam.

[0013] Step S6: When the coal spontaneous combustion prevention width B1 is greater than the coal spontaneous combustion prevention width B2, repeat step S5 and gradually increase the coal spontaneous combustion prevention width B2 according to the preset second step length until the coal spontaneous combustion prevention width B1 is less than or equal to the coal spontaneous combustion prevention width B2. Then determine the final coal spontaneous combustion prevention width as the current coal spontaneous combustion prevention width B2.

[0014] The determination of the pre-treatment width B1 for spontaneous combustion of coal based on the slope stability coefficient in the initial state and the preset first step length includes:

[0015] Let the width of each proactive governance be b. 1i Where i = 1, 2, ..., n, n is the total number of advance governance width times, and i is the i-th advance governance. Each advance governance width is increased by a first step length to obtain the advance governance width after increasing the first step length.

[0016] Based on the increased pre-treatment width after the first step, corresponding two-dimensional end slope models are established. The first stability coefficient F of the current two-dimensional end slope model is calculated using the two-dimensional rigid body limit equilibrium method. si ;

[0017] Based on the requirements for the safety reserve coefficient of open-pit coal mine slopes in the "Design Code for Open-pit Coal Mines", the slope safety reserve coefficient K1 is determined during the treatment process.

[0018] Comparing the first stability coefficients calculated in adjacent quadratic iterations, when the first stability coefficient F calculated in the (i-1)th iteration... si-1 The first stability coefficient F is greater than that calculated in the i-th time. si And the first stability coefficient F calculated in the i-th time si When the slope safety reserve coefficient K1 is greater than or equal to the current coal spontaneous combustion advance treatment width B1, determine the width of the slope B1.

[0019] The current proactive control width B1 for spontaneous coal combustion is determined by the following formula:

[0020] ;

[0021] Among them, B1 represents the current breadth of advanced governance for spontaneous combustion of coal. The advanced governance width is the length of the first step after the kth iteration.

[0022] The step of determining the coal spontaneous combustion control width B2 based on the slope stability coefficient in the initial state and the preset second step length includes:

[0023] Let the width of each coal spontaneous combustion control measure be b. 2l Where l = 1, 2, ..., m, m is the total number of coal spontaneous combustion control times, l is the l-th coal spontaneous combustion control time, and the width of each coal spontaneous combustion control time is increased by a second step length to obtain the coal spontaneous combustion control width after increasing the second step length;

[0024] At the B1 position of the coal spontaneous combustion pretreatment width, the waste material of the coal spontaneous combustion treatment width after the second step length is increased is replaced sequentially, and corresponding two-dimensional end slope models are established. The second stability coefficient F of the current two-dimensional end slope model is calculated using the two-dimensional rigid body limit equilibrium method. sl ;

[0025] Comparing the second stability coefficients calculated in adjacent quadratic iterations, when the second stability coefficient F calculated in the (l-1)th iteration... sl-1 The second stability coefficient F is greater than that calculated in the lth time. sl And the second stability coefficient F calculated in the lth time sl The stability coefficient F of the slope is greater than that of the initial state. s At that time, determine the current coal spontaneous combustion control width B2.

[0026] The current coal spontaneous combustion control width B2 is calculated as follows:

[0027] ;

[0028] Wherein, B2 represents the current width of coal spontaneous combustion control. The width of the coal spontaneous combustion control system is increased by the second step length for the p-th time.

[0029] Beneficial effects:

[0030] This invention proposes a method for the early control of spontaneous combustion in open-pit coal seams at the end of the coal face. This method effectively utilizes waste materials to pre-fill and treat end-face coal seams with high spontaneous combustion tendency, allowing for the extraction of large quantities of end-face coal resources, saving significant waste disposal space, and facilitating construction. Thus, it effectively achieves the goal of efficient, economical, environmentally friendly, and safe early control of coal spontaneous combustion. Attached Figure Description

[0031] Figure 1 This is a flowchart of a method for proactively controlling spontaneous combustion of coal at the end of an open-pit mine, as described in an embodiment of the present invention.

[0032] Figure 2 This is a schematic diagram of the end slope model selected in an embodiment of the present invention;

[0033] Figure 3 This is a schematic diagram of the evaluation results of the end slope model selected in this embodiment of the invention;

[0034] Figure 4 This is a schematic diagram of the intermediate process for determining the pre-control width B1 for spontaneous combustion of coal in an embodiment of the present invention;

[0035] Figure 5 This is a schematic diagram illustrating the determination of the pre-treatment width B1 for spontaneous combustion of coal in an embodiment of the present invention;

[0036] Figure 6 This is a schematic diagram of the intermediate process for determining the coal spontaneous combustion control width B2 in an embodiment of the present invention;

[0037] Figure 7 This is a schematic diagram illustrating the determination of the coal spontaneous combustion control width B2 in an embodiment of the present invention. Detailed Implementation

[0038] The specific implementation methods of this application will be further described in detail below with reference to the accompanying drawings and embodiments.

[0039] Example

[0040] This embodiment proposes a method for proactively controlling spontaneous combustion of coal at the end of open-pit mines, such as... Figure 1 As shown, it includes:

[0041] Step S1: Obtain the geometric parameters of the end slope;

[0042] In this embodiment, it is assumed that the end face profile of an open-pit coal mine is selected. A schematic diagram of the end face slope model is shown below. Figure 2 As shown. Based on the preliminary design specifications of the open-pit coal mine and subsequent construction, the geometric parameters of the end slope were obtained, including: the width of the transport platform (c), the width of the safety platform (d), the slope angle of the bench (a), the bench height (h), and other mining parameters.

[0043] Step S2: Obtain the physical and mechanical parameters of the rock and soil mass and the waste materials in the mining area;

[0044] In this embodiment, physical and mechanical parameters of the soil and rock mass and the waste materials in the mining area are obtained through physical and mechanical tests, including: unit weight γ, cohesion c, and internal friction angle. .

[0045] Step S3: Based on the geometric and physical parameters, establish a two-dimensional end slope model and use the two-dimensional rigid body limit equilibrium method to calculate the stability coefficient of the two-dimensional end slope model in the initial state.

[0046] In this embodiment, based on the geometric parameters obtained in step S1 and the physical and mechanical parameters obtained in step S2, a two-dimensional slope model with a selected end face section is established. The stability coefficient Fs of the slope in the initial state is calculated using the two-dimensional rigid body limit equilibrium method. Figure 3 As shown. The two-dimensional rigid body limit equilibrium method is existing technology and will not be described further in this application.

[0047] Step S4: Based on the stability coefficient of the slope in the initial state and the preset first step length, determine the coal spontaneous combustion advance treatment width B1, whereby the coal spontaneous combustion advance treatment width B1 is the maximum cumulative horizontal width of the end coal seam that can be mined inward.

[0048] The determination of the pre-treatment width B1 for spontaneous combustion of coal based on the slope stability coefficient in the initial state and the preset first step length includes:

[0049] Step S4.1: Let the width of each advance treatment be b. 1i Where i = 1, 2, ..., n, n is the total number of advance governance width times, and i is the i-th advance governance. Each advance governance width is increased by a first step length to obtain the advance governance width after increasing the first step length.

[0050] In this embodiment, it is assumed that the width of each advance treatment is b. 1i (i=1, 2, ..., n), and perform trial calculations by increasing the step size each time.

[0051] Step S4.2: Based on the increased pre-treatment width after the first step, establish corresponding two-dimensional end slope models. Use the two-dimensional rigid body limit equilibrium method to calculate the first stability coefficient F of the current two-dimensional end slope model. si ;

[0052] In this embodiment, the width of the advanced treatment for spontaneous combustion of coal is sequentially expanded by b. 11 b 12 , ..., b 1iCorresponding two-dimensional end slope models were established, and the first stability coefficient F of the current two-dimensional end slope model was calculated using the two-dimensional rigid body limit equilibrium method. si ,like Figure 4 As shown.

[0053] Step S4.3: Determine the slope safety reserve coefficient K1 during the treatment process according to the requirements of the "Design Code for Open-pit Coal Mines".

[0054] In this embodiment, the slope safety reserve coefficient K1 is 1.05.

[0055] Step S4.4: Compare the first stability coefficients calculated in adjacent quadratic iterations. When the first stability coefficient F calculated in the (i-1)th iteration... si -1 is greater than the first stability coefficient F calculated in the i-th time. si And the first stability coefficient F calculated in the i-th time si When the slope safety reserve coefficient K1 is greater than or equal to the current coal spontaneous combustion advance treatment width B1, such as... Figure 5 As shown, that is Where B1 represents the current breadth of advanced control measures for spontaneous combustion of coal. The advanced governance width is the length of the first step after the kth iteration.

[0056] Step S5: Determine the coal spontaneous combustion treatment width B2 based on the slope stability coefficient in the initial state and the preset second step length. The coal spontaneous combustion treatment width B2 is the cumulative horizontal width that needs to be replaced with waste material after the pre-treatment width B1 for coal spontaneous combustion in the end coal seam.

[0057] The step of determining the coal spontaneous combustion control width B2 based on the slope stability coefficient in the initial state and the preset second step length includes:

[0058] Step S5.1: Let the width of each coal spontaneous combustion control measure be b. 2l Where l = 1, 2, ..., m, m is the total number of coal spontaneous combustion control times, l is the l-th coal spontaneous combustion control time, and the width of each coal spontaneous combustion control time is increased by a second step length to obtain the coal spontaneous combustion control width after increasing the second step length;

[0059] In this embodiment, it is assumed that the width of each coal spontaneous combustion control measure is b. 2l (l=1, 2, ..., n), each time the step length is increased by one step length for trial calculation.

[0060] Step S5.2: At the location B1 of the coal spontaneous combustion pretreatment width, sequentially replace the waste material with the material corresponding to the increased coal spontaneous combustion treatment width after the second step length, and establish corresponding two-dimensional end slope models. Using the two-dimensional rigid body limit equilibrium method, calculate the second stability coefficient F of the current two-dimensional end slope model. sl ;

[0061] In this embodiment, the width of the fill is sequentially replaced at position B1. 21 b 22 , ..., b 2l For each type of waste material, a corresponding end slope model is established, and the stability coefficient F of the current end slope model is calculated using the two-dimensional rigid body limit equilibrium method. sl ,like Figure 6 As shown.

[0062] Step S5.3: Compare the second stability coefficients calculated in adjacent quadratic iterations. When the second stability coefficient F calculated in the (l-1)th iteration... sl -1 is greater than the second stability coefficient F calculated in the lth time. sl And the second stability coefficient F calculated in the lth time sl The stability coefficient F of the slope is greater than that of the initial state. s At that time, the current coal spontaneous combustion control width B2 is determined, that is... Where B2 represents the current width of coal spontaneous combustion control measures. The width of the coal spontaneous combustion control system is increased by the second step length for the p-th time.

[0063] Step S6: When the coal spontaneous combustion prevention width B1 is greater than the coal spontaneous combustion prevention width B2, repeat step S5 and gradually increase the coal spontaneous combustion prevention width B2 according to the preset second step length until the coal spontaneous combustion prevention width B1 is less than or equal to the coal spontaneous combustion prevention width B2. Then determine the final coal spontaneous combustion prevention width as the current coal spontaneous combustion prevention width B2.

[0064] In this embodiment, B1 and B2 are compared. When B1 When B2 is reached, repeat steps 5.1 to 5.3 to gradually increase the coal spontaneous combustion control width B2 until B2 is reached. At point B1, the final determination of the coal spontaneous combustion control width is B2, such as... Figure 7 As shown;

[0065] The various embodiments in this application are described in a progressive manner. The same or similar parts between the various embodiments can be referred to each other. Each embodiment focuses on describing the differences from other embodiments.

[0066] The scope of protection of this application is not limited to the embodiments described above. Obviously, those skilled in the art can make various modifications and variations to this disclosure without departing from the scope and spirit of this disclosure. If such modifications and variations fall within the scope of equivalent technology of this disclosure, then the intent of this disclosure also includes such modifications and variations.

Claims

1. A method for proactively controlling spontaneous combustion of coal at the end of an open-pit mine, characterized in that, include: Step S1: Obtain the geometric parameters of the end slope; Step S2: Obtain the physical and mechanical parameters of the rock and soil mass and the waste materials in the mining area; Step S3: Based on the geometric and physical parameters, establish a two-dimensional end slope model and use the two-dimensional rigid body limit equilibrium method to calculate the stability coefficient of the two-dimensional end slope model in the initial state. Step S4: Based on the stability coefficient of the slope in the initial state and the preset first step length, determine the coal spontaneous combustion advance treatment width B1, whereby the coal spontaneous combustion advance treatment width B1 is the maximum cumulative horizontal width of the end coal seam that can be mined inward. Step S5: Determine the coal spontaneous combustion treatment width B2 based on the slope stability coefficient in the initial state and the preset second step length. The coal spontaneous combustion treatment width B2 is the cumulative horizontal width that needs to be replaced with waste material after the pre-treatment width B1 for coal spontaneous combustion in the end coal seam. Step S6: When the coal spontaneous combustion prevention width B1 is greater than the coal spontaneous combustion prevention width B2, repeat step S5 and gradually increase the coal spontaneous combustion prevention width B2 according to the preset second step length until the coal spontaneous combustion prevention width B1 is less than or equal to the coal spontaneous combustion prevention width B2. Then determine the final coal spontaneous combustion prevention width as the current coal spontaneous combustion prevention width B2.

2. The method for proactively controlling spontaneous combustion of coal at the end of an open-pit mine according to claim 1, characterized in that, The determination of the pre-treatment width B1 for spontaneous combustion of coal based on the slope stability coefficient in the initial state and the preset first step length includes: Let the width of each proactive governance be b. 1i Where i = 1, 2, ..., n, n is the total number of advance governance width times, and i is the i-th advance governance. Each advance governance width is increased by a first step length to obtain the advance governance width after increasing the first step length. Based on the increased pre-treatment width after the first step, corresponding two-dimensional end slope models are established. The first stability coefficient F of the current two-dimensional end slope model is calculated using the two-dimensional rigid body limit equilibrium method. si ; Based on the requirements for the safety reserve coefficient of open-pit coal mine slopes in the "Design Code for Open-pit Coal Mines", the slope safety reserve coefficient K1 is determined during the treatment process. Comparing the first stability coefficients calculated in adjacent quadratic iterations, when the first stability coefficient F calculated in the (i-1)th iteration... si-1 The first stability coefficient F is greater than that calculated in the i-th time. si And the first stability coefficient F calculated in the i-th time si When the slope safety reserve coefficient K1 is greater than or equal to the current coal spontaneous combustion advance treatment width B1, determine the width of the slope B1.

3. The method for proactively controlling spontaneous combustion of coal at the end of an open-pit mine according to claim 2, characterized in that, The current proactive control width B1 for spontaneous coal combustion is determined by the following formula: ； Among them, B1 represents the current breadth of advanced governance for spontaneous combustion of coal. The advanced governance width is the length of the first step after the kth iteration.

4. The method for proactively controlling spontaneous combustion of coal at the end of an open-pit mine according to claim 1, characterized in that, The step of determining the coal spontaneous combustion control width B2 based on the slope stability coefficient in the initial state and the preset second step length includes: Let the width of each coal spontaneous combustion control measure be b. 2l Where l = 1, 2, ..., m, m is the total number of coal spontaneous combustion control times, l is the l-th coal spontaneous combustion control time, and the width of each coal spontaneous combustion control time is increased by a second step length to obtain the coal spontaneous combustion control width after increasing the second step length; At the B1 position of the coal spontaneous combustion pretreatment width, the waste material of the coal spontaneous combustion treatment width after the second step length is increased is replaced sequentially, and corresponding two-dimensional end slope models are established. The second stability coefficient F of the current two-dimensional end slope model is calculated using the two-dimensional rigid body limit equilibrium method. sl ; Comparing the second stability coefficients calculated in adjacent quadratic iterations, when the second stability coefficient F calculated in the (l-1)th iteration... sl-1 The second stability coefficient F is greater than that calculated in the lth time. sl And the second stability coefficient F calculated in the lth time sl The stability coefficient F of the slope is greater than that of the initial state. s At that time, determine the current coal spontaneous combustion control width B2.

5. A method for proactively controlling spontaneous combustion of coal at the end of an open-pit mine according to claim 4, characterized in that, The current coal spontaneous combustion control width B2 is calculated as follows: ； Wherein, B2 represents the current width of coal spontaneous combustion control. The width of the coal spontaneous combustion control system is increased by the second step length for the p-th time.

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