A Selection Method for Coal-based Solid Waste Type Functional Backfilling Materials

Abstract

The present invention discloses a method for selecting a coal-based solid waste type functional filling material, which takes the coal-based filling material as the main body to realize the multifunctionality of the filling material. The coal-based filling material mainly includes solid wastes such as coal slime and coal gangue generated during the coal mining process. Among them, the solid waste type refers to the role of solid waste disposal of the filling material. First, according to the actual situation of the mine, the geological condition characteristics are determined, and the differences in surrounding rock temperature, surrounding rock thermal conductivity, thickness of the main and secondary key strata, and uniaxial compressive strength are obtained, and the function selection is carried out based on different function characteristics. The function selection includes geothermal extraction, mine pressure perception, and gas sequestration. Finally, a coal-based solid waste type functional filling material is determined corresponding to the function selection. The present invention provides a method for selecting a coal-based solid waste type functional filling material for the actual needs of different geological conditions and mines, and provides an effective theoretical support for better realizing the green mining technologies of coal and heat co-mining, real-time mine pressure monitoring, or gas geological storage.

Description

Technical Field

[0001] The present invention relates to the technical field of comprehensive utilization of coal-based solid wastes and green coal mining, and particularly relates to a method for selecting coal-based solid waste type functional filling materials. Background Art

[0002] In recent years, with the increase of the coal resource mining depth, mines in the eastern region of China have gradually entered deep mining. One of the main problems in deep mining is the heat hazard problem. For many years, the geothermal heat in deep mines has mainly been treated in the form of heat hazards, and the underground heat sources have not been effectively utilized. Therefore, extracting the heat source of deep mines has become an urgent problem to be solved in the eastern mining areas at present. According to the actual geological conditions of the mine, the present invention proposes geothermal extraction type functional filling, mine pressure sensing type functional filling and gas sequestration type functional filling types and corresponding methods for selecting filling materials.

[0003] For mines with poor geological conditions, real-time monitoring of mine pressure is the guarantee for the safe production of the mine; the environmental impacts such as global warming caused by the emissions of greenhouse gases such as carbon dioxide have promoted scholars to study the methods of gas capture and collection and their filling, sequestration and utilization in coal mines. At the same time, along with the large-scale exploitation of coal resources, the current situation of a large amount of coal-based solid wastes piling up urgently needs to be changed. In order to utilize coal-based solid wastes on a large scale and resourcefully, the research and development of coal-based filling materials have been continuously developed and improved.

[0004] In the process of filling coal mining, in order to accurately select filling materials according to different geological conditions and actual requirements, a method for selecting coal-based solid waste type functional filling materials needs to be established, so as to realize the comprehensive utilization of coal-based solid wastes while ensuring production safety and achieve green coal mining. Summary of the Invention

[0005] Object of the Invention: Based on the main functional requirements of the above-mentioned coal-based filling materials, the coal-based solid waste type functional filling materials to be urgently studied in the present invention are divided into three categories, namely geothermal extraction type functional filling materials, mine pressure sensing type functional filling materials and gas sequestration type functional filling materials. In order to meet the requirements such as the utilization of mine geothermal resources, the present invention discloses a method for selecting coal-based solid waste type functional filling materials, mainly including, but not limited to, solid waste materials generated in the coal mining process such as coal slime, cement, fly ash and coal gangue. The solid waste type refers to the role of solid waste disposal of the filling materials.

[0006] First, determine the geological condition characteristics according to the actual situation of the mine. The geological conditions include good geological conditions, high geothermal temperature, poor geological conditions or stable roof. Secondly, conduct function selection based on different functional characteristics. The function selection includes geothermal extraction, gas sequestration, and mine pressure perception, and there are differences in their characteristics in terms of surrounding rock temperature, surrounding rock thermal conductivity, uniaxial compressive strength, and distribution of main and secondary key strata. Finally, determine a coal-based solid waste type functional filling material corresponding to the function selection. The present invention provides a theoretical reference for the selection method of coal-based solid waste type functional filling materials for mines with different geological conditions and actual needs, and provides effective theoretical support for better realizing the green mining technologies of coal and heat co-mining, real-time mine pressure monitoring, or gas geological storage.

[0007] Technical solution: The present invention provides a method for selecting a coal-based solid waste type functional filling material, including the following steps:

[0008] S1. Determine the geological condition characteristics according to the actual situation of the mine;

[0009] S2. Based on the geological condition characteristics, conduct function selection to determine the filling type;

[0010] S3. Based on the filling type, correspondingly determine the type of coal-based functional filling material;

[0011] Among them, the filling type includes geothermal extraction type functional filling, gas sequestration type functional filling, and mine pressure perception type functional filling, and the corresponding types of coal-based functional filling materials include geothermal extraction type functional filling materials, gas sequestration type functional filling materials, and mine pressure perception type functional filling materials.

[0012] Optionally, in an embodiment of the present invention, the coal-based functional filling material is a coal-based solid waste, and the coal-based solid waste includes at least any one of coal slime, cement, fly ash, and coal gangue.

[0013] Optionally, in an embodiment of the present invention, the geological condition characteristics include surrounding rock temperature and surrounding rock thermal conductivity.

[0014] Optionally, in an embodiment of the present invention, the geological condition characteristics further include the distribution of main and secondary key strata and uniaxial compressive strength.

[0015] Optionally, in an embodiment of the present invention, the distribution of main and secondary key strata includes key layer thickness, rock mass integrity coefficient, joint gap, and bedding spacing.

[0016] Optionally, in an embodiment of the present invention, the method makes a selection according to the following conditions:

[0017] (i) If the geological condition characteristics satisfy: surrounding rock temperature ≥ 40°C and surrounding rock thermal conductivity > 3.0 W / mK, then select the filling type as geothermal extraction type functional filling, and the corresponding type of coal-based functional filling material is geothermal extraction type functional filling material; if the conditions are not satisfied, it is necessary to further select from gas storage type functional filling materials and mine pressure sensing type functional filling materials.

[0018] Optionally, in an embodiment of the present invention, the selection from gas storage type functional filling materials and mine pressure sensing type functional filling materials includes:

[0019] (ii) If the geological condition characteristics satisfy: uniaxial compressive strength UCS ≥ 20 MPa and there are main and secondary key strata in the overlying strata, the thickness of the main and secondary key strata > 20 m, rock mass integrity coefficient > 0.75, joint gap > 3 m, bedding spacing > 2 m, then select the filling type as gas storage type functional filling, and the corresponding type of coal-based functional filling material is gas storage type functional filling material;

[0020] (iii) If not satisfied, then select the filling type as mine pressure sensing type functional filling, and the corresponding type of coal-based functional filling material is mine pressure sensing type functional filling material.

[0021] Optionally, in an embodiment of the present invention, the method is selected in the following order:

[0022] (i) If the geological condition characteristics satisfy: surrounding rock temperature ≥ 40°C and surrounding rock thermal conductivity > 3.0 W / mK, then select the filling type as geothermal extraction type functional filling, and the corresponding type of coal-based functional filling material is geothermal extraction type functional filling material; if the conditions are not satisfied, it is necessary to further select from gas storage type functional filling materials and mine pressure sensing type functional filling materials;

[0023] (ii) If the geological condition characteristics satisfy: uniaxial compressive strength UCS ≥ 20 MPa and there are main and secondary key strata in the overlying strata, the thickness of both the main and secondary key strata is above 20 m, the rock formation is complete, that is, the rock mass integrity coefficient > 0.75, joint gap > 3 m, bedding spacing > 2 m, then select the filling type as gas storage type functional filling, and the corresponding type of coal-based functional filling material is gas storage type functional filling material;

[0024] (iii) If the above geological condition characteristics are not satisfied, then select the filling type as mine pressure sensing type functional filling, and the corresponding type of coal-based functional filling material is mine pressure sensing type functional filling material;

[0025] The geothermal extraction - type filling body has certain thermal conductivity, can effectively absorb the heat in the surrounding rock, and conduct heat exchange with the medium (water) in the pipeline buried in the filling material, so as to develop and utilize the mine geothermal resources. The mechanical properties of the mine pressure - sensing filling material and the compactness of the filling body play a key role in the mine pressure manifestation of the filling stope, and it is applicable to the situation where real - time mine pressure monitoring is required in the mine. Gas - sequestration - type filling includes physical sequestration and chemical sequestration, which combines the sequestration of greenhouse gases with filling to effectively control greenhouse gas emissions. According to the characteristics of the three methods, the present invention uses the surrounding - rock temperature, the surrounding - rock thermal conductivity and the uniaxial compressive strength as the discrimination basis, and can quickly and simply determine how to select a more suitable filling type and the corresponding type of coal - based functional filling material under different geological - condition characteristics. For areas with relatively high geothermal temperature and relatively high thermal conductivity, the geothermal extraction - type can be selected; for areas with good geological conditions and stable roof, the gas - sequestration - type can be selected; for areas with poor geological conditions, the mine pressure - sensing type can be selected.

[0026] Beneficial effects: Based on the functional characteristics of the functional filling materials for geothermal extraction, gas sequestration and mine pressure sensing, the present invention establishes a method for selecting coal - based solid - waste - type functional filling materials, and gives the functional selection of filling materials corresponding to different mine geothermal temperatures, thermal conductivities, geological conditions and roof conditions. While solving the problem of coal - based solid - waste accumulation, it can more effectively realize the extraction and utilization of geothermal resources, conduct real - time monitoring of mine pressure or complete the capture and sequestration of greenhouse gases. This method can promote the safe and efficient production activities of coal mines, solve many environmental problems accompanying mining, is conducive to ensuring that coal - mining activities follow the path of green development, unifies with the pace of green coal - resource mining, and pays attention to the coordinated development of ecological protection. Brief Description of the Drawings

[0027] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the following will briefly introduce the drawings required for description in the embodiments. Obviously, the following - described drawings are only some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained based on these drawings.

[0028] Figure 1 It is a schematic flow chart for determining a coal - based solid - waste - type functional filling material of the present invention. Detailed Embodiments

[0029] The following will describe in detail a method for selecting a coal - based solid - waste - type functional filling material of the present invention with reference to the drawings.

[0030] The present invention discloses a method for selecting a coal-based solid waste type functional filling material, which mainly includes coal-based filling materials, including but not limited to solid waste materials generated during coal mining such as slime, cement, fly ash, and coal gangue. The solid waste type refers to the role of solid waste disposal of the filling material. First, determine the geological condition characteristics according to the actual situation of the mine. The geological conditions include good geological conditions, high ground temperature, poor geological conditions, or stable roof, etc. Secondly, based on different functional characteristics, perform functional selection. The functional selection includes geothermal extraction, gas sequestration, and mine pressure perception, and there are differences in their characteristics in terms of surrounding rock temperature, surrounding rock thermal conductivity, uniaxial compressive strength, and the distribution of main and secondary key strata. Finally, correspondingly determine a coal-based solid waste type functional filling material according to the functional selection. The present invention provides a theoretical reference for the method of selecting coal-based solid waste type functional filling materials for mines with different geological conditions and actual needs, and provides effective theoretical support for better realizing the green mining technologies of coal and heat co-mining, real-time mine pressure monitoring, or gas geological storage.

[0031] The present invention provides a method for selecting a coal-based solid waste type functional filling material, as Figure 1 shown, including the following steps:

[0032] S1. Determine the geological condition characteristics according to the actual situation of the mine;

[0033] S2. Based on the geological condition characteristics, perform functional selection to determine the filling type;

[0034] S3. Based on the filling type, correspondingly determine the type of coal-based functional filling material;

[0035] Among them, the filling type includes geothermal extraction type functional filling, gas sequestration type functional filling, and mine pressure perception type functional filling. The corresponding types of coal-based functional filling materials include geothermal extraction type functional filling materials, gas sequestration type functional filling materials, and mine pressure perception type functional filling materials.

[0036] As an implementation manner, the coal-based functional filling material is a coal-based solid waste, and the coal-based solid waste includes at least any one of slime, cement, fly ash, and coal gangue.

[0037] As an implementation manner, the geological condition characteristics include surrounding rock temperature, thermal conductivity, mining depth, distribution of main and secondary key strata, and uniaxial compressive strength.

[0038] As an implementation manner, the method is carried out in the following order:

[0039] (ⅰ) If the geological condition features meet the following: the surrounding rock temperature ≥ 40°C and the thermal conductivity of the surrounding rock > 3.0 W / mK, then select the filling type as geothermal extraction functional filling, and the corresponding type of coal-based functional filling material is geothermal extraction functional filling material. If the conditions are not met, further selection is required from gas sequestration functional filling materials and mine pressure sensing functional filling materials;

[0040] (ⅱ) If the geological condition features meet the following: the uniaxial compressive strength UCS ≥ 20 MPa and there are main and secondary key strata in the overlying strata, the thicknesses of the main and secondary key strata are both above 20 m, the rock formation is complete, i.e., the rock mass integrity coefficient > 0.75, the joint gap > 3 m, and the bedding spacing > 2 m, then select the filling type as gas sequestration functional filling, and the corresponding type of coal-based functional filling material is gas sequestration functional filling material.

[0041] (ⅲ) If the above geological condition features are not met, then select the filling type as mine pressure sensing functional filling, and the corresponding type of coal-based functional filling material is mine pressure sensing functional filling material.

[0042] The following further describes the present invention in conjunction with the accompanying drawings and embodiments. According to the following embodiments, the present invention can be better understood. However, those skilled in the art can easily understand that the specific material ratios, process conditions and their results described in the embodiments are only used to illustrate the present invention, and should not and will not limit the present invention described in detail in the claims.

[0043] Example 1

[0044] Taking a filling mine as an example, the specific implementation steps are as follows:

[0045] A certain mine enters the deep well mining stage, and the problem of high-temperature heat damage in deep wells has gradually attracted attention. High temperature not only affects the mechanical properties of the surrounding rock, but also seriously affects the production safety of the mine. The existing cooling technology in the mine mainly uses centralized air-conditioning cooling technology, resulting in a large cost burden and technical difficulties such as large depth and high pressure, and poor heat dissipation effect. Now, experimental control mining areas are set up in different mining areas under the same conditions in this mine. The No. 1 mining area maintains the existing cooling equipment and uses conventional filling technology, and the No. 3 mining area is the experimental mining area and uses the method for selecting coal-based solid waste type functional materials described in the present invention to select filling materials.

[0046] Investigate, statistically analyze the geological conditions of a filling mine. This mine uses vertical shaft single-level development, the main level is -835 m level, and the original rock temperature in some areas is as high as 45°C (meeting the requirement of above 40°C), the thermal conductivity of the surrounding rock is 3.16 W / mK, and the geothermal gradient is: 3.42°C / 100 m. It can be seen that this mine has a large mining depth and high geothermal temperature, and the thermal conductivity > 3.0 W / mK. Coal-based solid waste type functional filling materials for geothermal extraction should be selected.

[0047] In Mining Area 1, a centralized air-conditioning cooling system is adopted. The ventilation route is long, heat dissipation is difficult, and the cooling effect is poor. The air temperature in the mining and excavation working faces only drops by 2 - 3 °C, resulting in low efficiency. Working in high temperatures greatly reduces the comfort of workers. In Mining Area 3, a coal-based solid waste type functional backfilling material that extracts geothermal energy is used to fill the goaf. This backfilling material has high thermal conductivity, and geothermal energy is transferred to the circulating water for utilization, enabling efficient extraction of geothermal resources.

[0048] The air temperature in the mining and excavation working faces of Mining Area 3 drops by 8 - 10 °C. Geothermal energy is absorbed from the source, and the cooling effect is remarkable. Moreover, when the mine water just comes out of the ground, heat is directly extracted with little heat loss, and the system efficiency is high. Using this system can not only cool the mine, but also be used for winter shaft anti-freezing, heating for surrounding residents, bathing water, etc., with good social and economic benefits.

[0049] Example 2

[0050] With the continuous development of China's economy, it is difficult to change the current energy consumption structure and mode in a short time. In the next period, China's greenhouse gas emissions will continue to increase. Taking the coal-based solid waste type functional backfilling material for greenhouse gas CO2 sequestration as an example, experimental control mining areas are set up in different mining areas of the same mine under the same conditions. In Mining Area 110503, conventional backfilling technology is adopted, and in Mining Area 110505, which is the experimental mining area, the selection method of the coal-based solid waste type functional material described in the present invention is used to select the backfilling material.

[0051] Given that the original rock temperature of a backfilled mine is 34 °C and the thermal conductivity of the surrounding rock is 3.05 W / mk, which does not meet the condition that the surrounding rock temperature is greater than 40 °C, then the coal-based solid waste type functional backfilling material for geothermal extraction is not applicable. After investigation, the uniaxial compressive strength is 23 MPa, and there are main and secondary key strata in the overlying rock. The thicknesses of the main and secondary key strata are 32 m and 27 m respectively, the rock formation is complete, that is, the rock mass integrity coefficient is 0.95, the joint gap is 4.6 m, and the bedding spacing is 3.7 m. Then the selected backfilling type is gas sequestration type functional backfilling, and the corresponding type of the coal-based functional backfilling material is gas sequestration type functional backfilling material.

[0052] In Mining Area 110505, gas sequestration type functional backfilling material is used for backfilling mining, and the carbon dioxide sequestration amount reaches 7.17×10 5 m 3 . Compared with the conventional backfilling technology used in the 110503 working face, it has stronger functional advantages, can effectively reduce greenhouse gas emissions, and reduce the damage to the atmospheric environment.

[0053] Example 3

[0054] When the roof conditions are unstable, real-time monitoring of the mine pressure data is particularly important for the safety of the mine. In this invention, a comparative experiment was carried out in a certain mine. Conventional filling technology and the coal-based solid waste functional filling material described in this invention were respectively used for filling in two adjacent mining areas with the same geological conditions.

[0055] It is known that the original rock temperature of a filling mine is 36°C and the thermal conductivity of the surrounding rock is 3.12 W / mk, which does not meet the condition that the surrounding rock temperature is greater than 40°C. Therefore, the coal-based solid waste type functional filling material for geothermal extraction is not applicable. After investigation, the uniaxial compressive strength is 19 MPa, and there is only a main key stratum in the overlying strata. The thickness of the main key stratum is 23 m, and the rock mass is intact, that is, the rock mass integrity coefficient is 0.65, which no longer meets one of the conditions that the uniaxial compressive strength UCS≥20 MPa, there are main and secondary key strata in the overlying strata, the thickness of both the main and secondary key strata is more than 20 m, the rock mass is intact, that is, the rock mass integrity coefficient >0.75, the joint gap >3 m, and the bedding spacing >2 m. That is, the coal-based solid waste type functional filling material for geothermal extraction is not applicable. Then the filling type is selected as the mine pressure sensing type functional filling, and the corresponding type of the coal-based functional filling material is the mine pressure sensing type functional filling material.

[0056] Conventional filling technology was used in the 75th mining area; the mine pressure sensing type functional filling material was used for filling in the 76th mining area. The experimental results show that the mine pressure range sensed by the mine pressure in the 76th mining area is 56% higher than that in the 75th mining area, which can more sensitively and immediately monitor the manifestation of the mine pressure and improve the safety of the mine exploitation.

[0057] The above is only the preferred implementation manner of the present invention. It should be noted that for those of ordinary skill in the art, without departing from the principle of the present invention, several improvements and refinements can be made, and these improvements and refinements should also be regarded as the protection scope of the present invention.

Claims

1. A method for selecting a coal-based solid waste type functional filling material, characterized in that It includes the following steps: S1. Determine the geological condition characteristics according to the actual situation of the mine; S2. Based on the geological condition characteristics, conduct function selection to determine the filling type; S3. Based on the filling type, correspondingly determine the type of coal-based functional filling material; Among them, the filling type includes geothermal extraction type functional filling, gas sequestration type functional filling, and mine pressure sensing type functional filling, and the corresponding types of coal-based functional filling materials include geothermal extraction type functional filling materials, gas sequestration type functional filling materials, and mine pressure sensing type functional filling materials; The geological condition characteristics include the surrounding rock temperature, the thermal conductivity of the surrounding rock, and also include the distribution of the main and secondary key strata and the uniaxial compressive strength; the distribution of the main and secondary key strata includes the key stratum thickness, the rock mass integrity coefficient, the joint gap, and the bedding spacing; The method is selected according to the following conditions: (ⅰ) If the geological condition characteristics meet: the surrounding rock temperature ≥ 40°C and the thermal conductivity of the surrounding rock > 3.0 W / mk, then select the filling type as geothermal extraction type functional filling, and the corresponding type of coal-based functional filling material is geothermal extraction type functional filling material; if the conditions are not met, it is necessary to further select from gas sequestration type functional filling materials and mine pressure sensing type functional filling materials; The selection from gas sequestration type functional filling materials and mine pressure sensing type functional filling materials includes: (ⅱ) If the geological condition characteristics meet: the uniaxial compressive strength UCS ≥ 20 MPa and there are main and secondary key strata in the overlying strata, the thickness of the main and secondary key strata > 20 m, the rock mass integrity coefficient > 0.75, the joint gap > 3 m, and the bedding spacing > 2 m, then select the filling type as gas sequestration type functional filling, and the corresponding type of coal-based functional filling material is gas sequestration type functional filling material; (ⅲ) If not met, then select the filling type as mine pressure sensing type functional filling, and the corresponding type of coal-based functional filling material is mine pressure sensing type functional filling material.

2. The method according to claim 1, characterized in that, The coal-based functional filling material is coal-based solid waste, and the coal-based solid waste includes at least any one of coal slime, cement, fly ash, and coal gangue.

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