Study on Gas Control Methods Optimization for Mining Safety

Effective gas control is of significance for safe efficient coal mining in Haizi Coal Mine and other mines with similar geological conditions. This study concentrates on gas control theories and techniques in multiple coal seams of Haizi Coal Mine (No. 7, No. 8, No. 9, and No. 10 coal seam from top to bottom). To minimize risk of high gas emission and outburst hazard, No. 10 seam was mined first as a protective seam prior to the mining of its overlying outburst-prone No. 7, No. 8, and No. 9 seam. Four gas drainage measures were determined for gas control, including cross-measure boreholes into overlying coal seams, surface goaf wells, roof boreholes, and roof gas drainage roadway. These gas control measures, if implemented through entire coal seam extraction, would be possibly uneconomic. An investigation was undertaken to analyze effects of those four measures on gas emission, methane concentration, and gas drainage quantity in No. 2 1024 mining panel of No. 10 seam. Results indicate that the highly expensive gas drainage measure of a roof roadway has poor drainage performance and could be effectively replaced by roof boreholes. When adopting the optimized combination of gas drainage measures, drainage efficiency of No. 7 seam, No. 8 seam, and No. 9 seam could reach 58.64% and decrease gas pressure to be below 0.74 MPa. Outcomes of this study could provide beneficial guidance not only for gas drainage design optimization in Haizi Coal Mine but also for other multiple-seam mines with similar mining and geological conditions, for increasing gas drainage efficiency and guaranteeing mining safety.

Download Full-text

Features of Jianshanchong Klippe and its Control to Gas Geology at Qingshan Coal Mine, Jiangxi Province

Applied Mechanics and Materials ◽

10.4028/www.scientific.net/amm.164.501 ◽

2012 ◽

Vol 164 ◽

pp. 501-505

Author(s):

Zhi Gen Zhao ◽

Jia Chen ◽

Jia Ping Yan

Keyword(s):

Coal Seam ◽

Coal Mine ◽

Emission Rate ◽

Coal And Gas Outburst ◽

Jiangxi Province ◽

Coal Seams ◽

Gas Emission ◽

Gas Outburst ◽

Transverse Profile ◽

Tectonic Coal

The coal and gas outburst is serious at Qingshan Coal Mine of Jiangxi Province, so it is of significance to research the features of Jianshanchong klippe and its control to gas geology. The research reveals that: Jianshanchong klippe is distributed from the east boundary of Qingshan Coal Mine to No. 45 Exploration Line, its transverse profile is like a funnel while its longitudinal profile is like a wedge, northwest side of the klippe is thicker and deeper while southeast side is thinner and more shallow. Because of the cover and insert of Jianshanchong klippe, the structure of coal-bearing strata is more complex, some secondary folds are formed, and also, the coal seam is changed greatly, the tectonic coal is well developed and the coal seam is suddenly thickening or thinning. Due to the effect of Jianshanchong klippe, the coal and gas outbursts occur in the area of secondary folds, thicker coal seams or tectonic coals. Concerning the prediction of gas geology in deep area, in view of the facts including simpler structure, stable coal seam and decreased thickness, the gas emission rate and the coal and gas outburst will decrease in Fifth and Sixth Mining Level than that in Second and Third Mining Level

Download Full-text

Gas Distribution Mechanism in Goaf during Combined Drainage of Upper Corner Buried Pipeline and Intubation for Thick Coal Seams

Lithosphere ◽

10.2113/2021/8308256 ◽

2021 ◽

Vol 2021 (Special 4) ◽

Author(s):

Zhe Li ◽

Fangtian Wang ◽

Shuai Ren ◽

Guannan Liu

Keyword(s):

Buried Pipeline ◽

Coal Seams ◽

Gas Drainage ◽

Gas Concentration ◽

Geological Conditions ◽

Key Issues ◽

Fluent Software ◽

Gas Control ◽

Drainage Effect ◽

And Control

Abstract The prevention of gas overrun in the panel is one of the key issues on green mining. In this paper, a physical goaf model was established based on the geological production conditions of a coal seam in a coal mine in Henan Province, and the combined drainage technology by burying and spilling pipeline in the upper corner was proposed. The Fluent software was used to simulate the changes of gas mass fraction and flow field distribution when the gas is extracted from the goaf without the gas pipeline, with a single buried pipeline, and with the combination of buried and spilled pipelines. Analysis and simulation showed that in the absence of drainage pipelines, the gas concentrations in both the return airway and the upper corner are up to 1.2%, which failed to meet the gas prevention and control standard on the mine. In the case of gas drainage with a single buried pipeline, the average gas concentration in the return airway was 0.7%, and only the gas concentration in the upper corner was up to 1.1%, which failed to meet the gas control standards on the mine’s panel. However, the maximum gas concentration in the combined drainage was reduced from 1.1% to 0.6%, which indicates that the technology can greatly reduce gas concentration, but there is still a gap from the mine’s gas control standard. Therefore, the impacts of the lengths of pipelines buried in different goafs on the gas drainage effect in the goaf were studied, and it was concluded that the reasonable length of pipelines buried in the goaf under the geological conditions was 20 m. This technology not only solves the problem of gas overrun in the panel but also realizes the utilization of gas resources in the goaf. The research results are of guiding significance for pipeline laying and the drainage technology in the upper corners on the U-shaped ventilation panel.

Download Full-text

Speculum Observation and Trajectory Measurement in Gas Extraction Drilling: A Case Study of Changling Coal Mine

Geofluids ◽

10.1155/2021/5545067 ◽

2021 ◽

Vol 2021 ◽

pp. 1-16

Author(s):

Enbiao Zhao ◽

Kangnan Li ◽

Xin Yang ◽

Nan Deng

Keyword(s):

Coal Seam ◽

Coal Mine ◽

Efficient Production ◽

Drilling Process ◽

Coal Seams ◽

Adjacent Layer ◽

Gas Drainage ◽

High Level ◽

Trajectory Measurement ◽

Drainage Borehole

Coal will still be China’s basic energy for quite a long time. With the increase of mining depth, gas content and pressure also increase. The problems of gas emission and overrun affect the safety and efficient production of coal resource to a certain extent. In this work, the field test of gas drainage borehole peeping and trajectory measurement in coal seam of Changling coal mine are carried out. These coal seams include C5b coal seam, upper adjacent C5a coal seam, C6a coal seams, C6c in lower adjacent strata, and C5b coal seam in high-level borehole. The view of gas drainage borehole peeping and trajectory measurement in the working seam, upper adjacent layer, lower adjacent layer, and high position are obtained. It is found that the hole collapses at the position of about 20 m in both adjacent strata and high-level boreholes, and there are a lot of cracks in the high-level boreholes before 12 m. The deviation distance of high-level borehole is large, and the actual vertical deviation of upper adjacent layer is small. Finally, the strategies to prevent the deviation of drilling construction are put forward. It includes four aspects: ensuring the reliability of drilling equipment, reasonably controlling the drilling length, standardizing the drilling, and reasonably selecting the drilling process parameters.

Download Full-text

Control of the Internal and External Staggered Distance of Coal Mining Face to the Water-Conducting Fissures in the Overlying Strata of the Near Coal

Advances in Civil Engineering ◽

10.1155/2021/1499675 ◽

2021 ◽

Vol 2021 ◽

pp. 1-12

Author(s):

Zhiyuan Jin ◽

Tao Peng

Keyword(s):

Coal Seam ◽

Coal Mining ◽

Coal Mine ◽

Calculation Formula ◽

Coal Seams ◽

Coal Face ◽

Geological Conditions ◽

Mining Face ◽

Seam Mining ◽

Water Proof

In Northwest China, rainfall is low, water resources are scarce, and the ecological environment is fragile. For shallow-buried and close-spaced coal seams with a thickness of upper coal bed >60∼70 m, the water-conducting fissures of the overlying rock will not penetrate the water-isolating layer after the upper coal seam is mined; the internal and external gap angles of the water-conducting fissures are not generated from the water-isolating layer. We set out to explore the critical internal and external dislocations for the second significant development of water-conducting fissures in the overlying rock after coal mining under control. A calculation model for the critical internal and external staggered distances of coal mining face in shallow-buried and close-spaced coal seams is established, the calculation formula is given, and the calculation formula for the critical seam mining ratio under the condition of internal staggered mining mode is given. Numerical simulation performed by UDEC methods: taking the overburden strata in the shallow-buried and close-spaced coal seam mining area of Shigetai Coal Mine as a prototype, it was verified that the critical internal and external offsets of the coal mining face in shallow-buried and close-spaced coal seams have a significant effect on the overlying water flow cracks in the mining of the lower coal seam. For the feasibility of developmental control, according to the engineering geological conditions of Shigetai, through the calculation method of external staggered distance, it is concluded that the distance of the open cut of the lower coal face and the upper coal face is only 21∼27 m, which is much smaller than the water barrier. It does not produce the critical distance of the water-conducting cracks. Therefore, in the process of mining the lower coal seam, the water-proof layer will produce water-conducting cracks, lose its water-proof performance, and cause water loss. This is also the cause of the water inrush accident in Shigetai Coal Mine.

Download Full-text

The Research of Gas Drainage Technology in Daning Coal Mine

Applied Mechanics and Materials ◽

10.4028/www.scientific.net/amm.580-583.2558 ◽

2014 ◽

Vol 580-583 ◽

pp. 2558-2563 ◽

Cited By ~ 2

Author(s):

Zhong Ming Zhao ◽

Gang Wang

Keyword(s):

Coal Seam ◽

Coal Mine ◽

Clean Energy ◽

Gas Pressure ◽

Emission Sources ◽

Gas Emission ◽

Gas Drainage ◽

Drainage Rate ◽

Safe Production

3# coal seam of Daning coal mine is outburst,thus severely restricting the safe production. Based on the analysis of gas emission sources and the logical drainage parameters, firstly, Daning coal mine arranged some drilling fields, then utilized the VLD-1000-type rig to drill boreholes, achieving the integrated gas drainage of the coal seam and goaf. Finally, there is a test on the drainage result. The results showed that, through this kind of integrated gas drainage technology, the highest value of gas pressure in the coal seam reduced to 0.63MPa from 1.95MPa after twelve months’ drainage, and the gas drainage rate of the whole mine reached 77.6%, achieving efficient use of gas clean energy.

Download Full-text

Reasonable Entry Layout of Lower Seam in Multi-Seam Mining Based on Numerical Simulation

Applied Mechanics and Materials ◽

10.4028/www.scientific.net/amm.295-298.2980 ◽

2013 ◽

Vol 295-298 ◽

pp. 2980-2984

Author(s):

Xiang Qian Wang ◽

Da Fa Yin ◽

Zhao Ning Gao ◽

Qi Feng Zhao

Keyword(s):

Numerical Simulation ◽

Stress Distribution ◽

Coal Seam ◽

Coal Mine ◽

Abutment Pressure ◽

Surrounding Rock ◽

Geological Conditions ◽

Seam Mining

Based on the geological conditions of 6# coal seam and 8# coal seam in Xieqiao Coal Mine, to determine reasonable entry layout of lower seam in multi-seam mining, alternate internal entry layout, alternate exterior entry layout and overlapping entry layout were put forward and simulated by FLAC3D. Then stress distribution and displacement characteristics of surrounding rock were analyzed in the three ways of entry layout, leading to the conclusion that alternate internal entry layout is a better choice for multi-seam mining, for which makes the entry located in stress reduce zone and reduces the influence of abutment pressure of upper coal seam mining to a certain extent,. And the mining practice of Xieqiao Coal Mine tested the results, which will offer a beneficial reference for entry layout with similar geological conditions in multi-seam mining.

Download Full-text

Influences of Mining Depths of Coal Faces in Duanwang Coal Mine on the Gas Emission Law

Applied Mechanics and Materials ◽

10.4028/www.scientific.net/amm.295-298.2874 ◽

2013 ◽

Vol 295-298 ◽

pp. 2874-2878

Author(s):

Xin Xian Zhai ◽

Yan Wei Zhai ◽

Shi Wei Zhang

Keyword(s):

Theoretical Analysis ◽

Coal Mine ◽

Production Capacity ◽

Control Measures ◽

Shanxi Province ◽

Coal Face ◽

Gas Emission ◽

Average Value ◽

Mining Depth ◽

Selection Of

Duanwang Coal Mine in Shanxi province, China, is located at north of Qinshui coalfield which gently inclined and thick seams have been mined. Authorized production capacity of the coal mine is 1.8Mt/a. With the increase of mining depth, the mine gas emission quantity increased. The mine became high gassy one from low gassy mine. Using field measurement and theoretical analysis methods, the following conclusion can be drawn. Gas emission quantity of coal face is directly correlated with mining depth. With the increase of mining depth, both absolute and relative gas emission quantities at coal face increased. The gradient of gas emission quantity was 0.0438-0.1338m3/t/m, the average value was 0.1062m3/t/m. These results would provide a foundation for prediction of the gas emission quantity and selection of gas control measures.

Download Full-text

Substantiation of Safe Conditions During Undermining of Hydraulic Waste Disposal

E3S Web of Conferences ◽

10.1051/e3sconf/20184101007 ◽

2018 ◽

Vol 41 ◽

pp. 01007

Author(s):

Yuriy Kutepov ◽

Aleksandr Mironov ◽

Maksim Sablin ◽

Elena Borger

Keyword(s):

Rock Mass ◽

Waste Disposal ◽

Coal Mine ◽

Water Body ◽

Water Inflow ◽

Open Pit ◽

Coal Seams ◽

Geological Conditions ◽

Mine Workings ◽

Mine Dump

This article considers mining and geological conditions of the site “Blagodatny” of the mine named after A.D. Ruban located underneaththe old open pit coal mine and the hydraulic-mine dump. The potentially dangerous zones in the undermined rock mass have been identified based onthe conditions of formation of water inflow into mine workings. Safe depthof coal seams mining has been calculated depending on the type of water body – the hydraulic-mine dump.

Download Full-text

Prediction Model for Spontaneous Combustion of Coal around Boreholes Using Bedding Gas Drainage

Shock and Vibration ◽

10.1155/2021/5533054 ◽

2021 ◽

Vol 2021 ◽

pp. 1-11

Author(s):

Youxin Zhao ◽

Qingjie Qi ◽

Xinlei Jia

Keyword(s):

Coal Seam ◽

Coal Mine ◽

Negative Pressure ◽

Spontaneous Combustion ◽

Orthogonal Test ◽

Gas Drainage ◽

Positive Linear Correlation ◽

Drainage Hole ◽

Spontaneous Combustion Of Coal ◽

Fractured Coal

To accurately and reliably predict the time of spontaneous combustion of fractured coal around a borehole induced by gas drainage along the seam, this study performed an orthogonal test taking the No. 10 Coal Mine of Pingdingshan as the research object, in terms of the suction negative pressure and coal seam buried depth. COMSOL Multiphysics was used to model the orthogonal test results, and a multielement statistical analysis of four factors and their relationships with the spontaneous combustion of coal around the borehole and a single-factor analysis in line with the site conditions were performed on the modeling results through multiple regression. The results showed a nonlinear regression relationship between the sealing hole length, sealing hole depth, negative pressure, and coal seam depth and the spontaneous combustion of the coal around the gas drainage borehole; the prediction regression model is significant. Taking the field gas drainage in the No. 10 Coal Mine of Pingdingshan as an example, the relationship between the time of spontaneous combustion of gas drainage and the drainage pressure follows a power of two. When the drainage negative pressure is less than 45 kPa, the coal around the borehole is more likely to undergo spontaneous combustion with increasing pressure, and the sealing hole length has a positive linear correlation with the time of spontaneous combustion of the coal around the borehole. When the sealing hole length is 23 m, the time of spontaneous combustion of the coal around the gas drainage hole is >500 days, and the coal around the borehole does not easily undergo spontaneous combustion. When the sealing depth is 15 m, the time of spontaneous combustion of the coal around the gas drainage hole is 76 days, which is most likely to cause spontaneous combustion.

Download Full-text

Study on Reservoir Properties and Critical Depth in Deep Coal Seams in Qinshui Basin, China

Advances in Civil Engineering ◽

10.1155/2019/1683413 ◽

2019 ◽

Vol 2019 ◽

pp. 1-7

Author(s):

Guiqiang Zheng ◽

Bin Sun ◽

Dawei Lv ◽

Zhejun Pan ◽

Huiqing Lian

Keyword(s):

Coal Seam ◽

Step Change ◽

Gas Content ◽

Burial Depth ◽

Critical Depth ◽

Coal Seams ◽

Reservoir Properties ◽

Qinshui Basin ◽

Geological Conditions ◽

Change Characteristics

Coalbed methane (CBM) reservoir properties and relationship of properties with burial depth were studied based on the data derived from 204 deep CBM production wells in Qinshui Basin, China. Through the study, it is found that permeability and porosity decrease with the increase of burial depth and the decreasing trend shows step-change characteristics at a critical burial depth. They also show divisional characteristics at certain burial depth. Gas content, geostress, and geotemperature increase with the increase of burial depth, and the increasing trend shows step-change characteristics and also have divisional characteristics at certain burial depth. Based on the previous study on the reservoir property changes with burial depth, three series of critical depth using different parameters are obtained through simulating the critical depth using the BP neural network method. It is found that the critical depth is different when using different parameters. Combined the previous study with the normalization of three different parameter types, the critical depth in Qinshui Basin was defined as shallow coal seam is lower than 650 m and transition band is 650–1000 m, while deep coal seam is deeper than 1000 m. In deep coal seams, the geological conditions and recovery becomes poor, so it can be defined as unfavorable zones. Therefore, other development means, for example, CO2 injection, need to be used to accelerate the deep coal methane development.

Download Full-text