scholarly journals Study on the technology of enhancing permeability by deep hole presplitting blasting in Sanyuan coal mine

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Dan Zhao ◽  
Mingyu Wang ◽  
Xinhao Gao
Keyword(s):  
Coal Seam ◽  
Coal Mine ◽  
Rock Blasting ◽  
Deep Hole ◽  
Positive Effects ◽  
Single Hole ◽  
Permeability Enhancement ◽  
Damage Degree ◽  
Coal Rock ◽  
Gas Coal

AbstractTo reduce gas disasters in low permeability and high gas coal seams and improve gas predrainage efficiency, conventional deep hole presplitting blasting permeability increasing technology was refined and perfected. The damage degree of coal and rock blasting was quantitatively evaluated by using the value range of the damage variable D. According to the actual field test parameters of coal seam #3 in the Sanyuan coal mine, Dlim = 0.81 ~ 1.0 was the coal rock crushing area, Dlim = 0.19 ~ 0.81 was the coal rock crack area, and Dlim = 0 ~ 0.19 was the coal rock disturbance area. The blasting models under different blasting parameters were established by ANSYS/LS-DYNA software. The influence radius of single-hole blasting was 3.1 m, the hole diameter of double-hole blasting was 113 mm, the hole spacing was 5.5 m, and the delayed blasting time was 25 ms. According to the numerical simulation results, the determined parameters were tested on the working face of the 1312 transportation roadway in coal seam #3 of the Sanyuan coal mine. The results show that after blasting, the permeability of the original coal seam was increased by more than 30 times, the gas concentration was increased by 2.16 times, and the single hole purity and mixing volume were increased by 4.73 and 4.27 times, respectively. The positive effects of deep hole presplitting blasting permeability enhancement technology on the pressure relief and permeability enhancement of a low pressure and high gas coal seam were determined.

scholarly journals Study on the Technology of Enhancing Permeability by Millisecond Blasting in Sanyuan Coal Mine

2021 ◽  
Vol 2021 ◽  
pp. 1-12
Author(s):  
Dan Zhao ◽  
Mingyu Wang ◽  
Xinhao Gao
Keyword(s):  
Coal Seam ◽  
Coal Mine ◽  
Simulation Software ◽  
Low Permeability ◽  
Time Interval ◽  
Rock Blasting ◽  
Deep Hole ◽  
Coal Seams ◽  
Coal Rock ◽  
Gas Coal

To reduce gas disasters in low permeability and high-gas coal seams and improve gas predrainage efficiency, conventional deep-hole presplitting blasting permeability increasing technology was refined and perfected. The numerical calculation model of presplitting blasting was established by using ANSYS/LS-DYNA numerical simulation software. The damage degree of coal and rock blasting was quantitatively evaluated by using the value range of the damage variable D. According to the actual field test parameters of coal seam #3 in the Sanyuan coal mine, Dlim = 0.81–1.0 was the coal rock crushing area, Dlim = 0.19–0.81 was the coal rock crack area, and Dlim = 0–0.19 was the coal rock disturbance area. By comparing and analysing the damage distribution nephogram of coal and rock mass under the influence of different millisecond blasting time interval and the blasting effect of simulation model, the optimal layout parameters of multilayer through cracks were obtained theoretically. And, the determined parameters were tested on the working face of the 1312 transportation roadway in coal seam #3 of the Sanyuan coal mine. The permeability effect was compared and analysed through the analysis of the gas concentration, gas purity, and mixing volume before and after the implementation of deep-hole presplitting blasting antireflection technology, as well as the change of gas pressure, attenuation coefficient, permeability coefficient, and other parameters between blasting coal seams. The positive role of millisecond blasting in reducing pressure and increasing permeability in low permeability and high-gas coal seam were determined.

scholarly journals Permeability enhancement of deep hole pre-splitting blasting in the low permeability coal seam of the Nanting coal mine

PLoS ONE ◽  
2018 ◽  
Vol 13 (6) ◽  
pp. e0199835 ◽  
Author(s):  
Zhengyi Ti ◽  
Feng Zhang ◽  
Jin Pan ◽  
Xiaofei Ma ◽  
Zheng Shang
Keyword(s):  
Coal Seam ◽  
Coal Mine ◽  
Low Permeability ◽  
Deep Hole ◽  
Permeability Enhancement

scholarly journals A Study of the Laws of Abnormal Gas Emissions and the Stability Controls for Coal Mine Walls in Deeply Buried High-Gas Coal Seams

2020 ◽  
Vol 2020 ◽  
pp. 1-12
Author(s):  
Anying Yuan ◽  
Hao Hu ◽  
Qiupeng Yuan
Keyword(s):  
Coal Seam ◽  
Water Content ◽  
Coal Mine ◽  
Gas Diffusion ◽  
Hard Coal ◽  
Coal Seams ◽  
Gas Emissions ◽  
Soft Coal ◽  
Pressure Water ◽  
Gas Coal

At the present time, it is considered to be of major significance to study the gas emission law and stability controls of coal bodies in deeply buried high-gas coal seams. For this reason, in view of the specific problems of gas emissions caused by unstable rib spalling in coal mine walls, comprehensive research methods were adopted in this study, in order to conduct an in-depth examination of micropore structure parameters, gas desorption, diffusion laws, and coal stability levels. The results showed that the development degree of the pores above the micropores, as well as the small pores in soft coal seams, was better than those observed in hard coal seams. In addition, the gas outburst phenomenon was found to have more easily formed in the soft coal seams. The coal body of the No. 6 coal seam in the Xieqiao Coal Mine not only provided the conditions for gas adsorption but also provided dominant channels for gas diffusion and migration. The abnormal gas emissions of the No. 6 coal seam were jointly caused by the relatively developed pores above the small holes in the coal body, rib spalling of coal mine walls, and so on. The research results also revealed the evolution law of mechanical characteristics of the No. 6 coal seam under different water content conditions. It was found that the strength levels of the No. 6 coal seam first increased and then decreased with the increase in water content, and the water content level at the maximum strength of the coal seam was determined to be 7.09%. This study put forward a method which combined the water injection technology of long-term static pressure water injections in deep coal mining holes and real-time dynamic pressure water injections in shallower holes. Field experiments were successfully carried out.

Study on Parameters of Deep-Hole Loose Blasting under the Condition of High Stress

2014 ◽  
Vol 644-650 ◽  
pp. 646-649
Author(s):  
Zhi Tao Zheng ◽  
Ying Xu
Keyword(s):  
Theoretical Analysis ◽  
Coal Mine ◽  
High Stress ◽  
Calculation Formula ◽  
Rock Blasting ◽  
Deep Hole ◽  
Design Work ◽  
Hole Wall ◽  
Deep Rock ◽  
Reference Design

The hole wall crushed and fractured zones length has been derived theoretically,and put forward the calculation formula of blasting crushing circle and radius of the corresponding fracture zone.Corresponding to the deep rock blasting parameters design on the basis of theoretical analysis,then lead to the reasonable parameters.These can provide certain reference design work for coal mine deep rock blasting parameters.

Modeling of seismic wave propagation around coal mine roadway with presence of excavation-damaged zone

2020 ◽  
Author(s):  
Rafał Czarny ◽  
Michał Malinowski
Keyword(s):  
Free Surface ◽  
Coal Seam ◽  
Group Velocity ◽  
Coal Mine ◽  
Fundamental Mode ◽  
Body Waves ◽  
Velocity Anomaly ◽  
Excavation Damaged Zone ◽  
Damaged Zone ◽  
Coal Rock

<p>In-seam seismic methods have been widely used in underground coal mine exploitation since early 80’s. They are helpful for identification of stress concentration zones or to locate geological disturbances within the coal seam. Usually, such surveys are optimized to perform seismic tomography. Therefore, sources and receivers are located on the opposite sides of the longwall. Results are produced in form of velocity maps of body-waves for rock-coal-rock medium or maps of group velocity and frequency of Airy-phase of dispersive waves trapped inside the coal seam, so-called channel waves. However, with the above geometry, the high-resolution imaging of the rock mass close to the roadway, including excavation-damaged zone (EDZ), is hampered by the available ray coverage.  In order to overcome this limitation, sources and receivers should be mounted in the same roadway. There is also a fundamental problem contributing to the lack of a robust method to image such area, which is the complexity of the seismic wavefield in the vicinity of the EDZ in a coal seam, where both surface tunnel waves and Rayleigh and Love-type channel waves overlap. We address this problem using numerical simulations. We use finite-difference method and viscoelastic model with petrophysical parameters for coal and host rock layers representative for the Upper Silesia mining district. First, we analyze seismic waves propagation within simple rock-coal-rock model, particularly channel waves dispersion properties. Then, we add a roadway with 3-meter thick EDZ to the model. Velocity and density within the EDZ linearly decrease up to 70% close to the free surface of excavation. By analyzing particle motion close to the free-surface, we observe that for very short wavelengths, the main energy is traveling as a fundamental mode of Rayleigh surface tunnel wave (for horizontal components). However, for longer wavelengths, the main energy is focused around frequency of Airy-phase of fundamental mode of Love-type channel wave. Eventually, we insert 10% Gaussian-shape velocity anomaly with 20 m width in the middle of the roadway to the model and investigate changes in frequency and group velocity of Airy-phase of Love-type channel waves for different offsets. We notice that the group velocity and frequency of maximum energy correspond to the velocity anomaly. For longer offsets, these parameters are approaching theoretical values for undisturbed medium. We conclude that because the group velocity of the Airy-phase is close to the coal S-wave velocity, it can be possible to image the velocity of such wave in the vicinity of the roadway, especially when the thickness of the coal seam is known.  </p><p> </p><p>This research is supported by Polish National Science Centre grant no UMO-2018/30/Q/ST10/00680.</p>

Phosphorus minerals in tonstein; coal seam 405 at Sośnica-Makoszowy coal mine, Upper Silesia, southern Poland

2013 ◽  
Vol 63 (2) ◽  
pp. 271-281 ◽  
Author(s):  
Magdalena Kokowska-Pawłowska ◽  
Jacek Nowak
Keyword(s):  
Trace Elements ◽  
Coal Seam ◽  
Mineral Composition ◽  
Coal Mine ◽  
Chemical Compositions ◽  
Coal Basin ◽  
Upper Silesia ◽  
Southern Poland ◽  
Basin Area

Abstract Kokowska-Pawłowska, M. and Nowak, J. 2013. Phosphorus minerals in tonstein; coal seam 405 at Sośnica- Makoszowy coal mine, Upper Silesia, southern Poland. Acta Geologica Polonica, 63 (2), 271-281. Warszawa. The paper presents results of research on tonstein, which constitutes an interburden in coal seam 405 at the Sośnica- Makoszowy coal mine, Makoszowy field (mining level 600 m), Upper Silesia, southern Poland. The mineral and chemical compositions of the tonstein differ from the typical compositions described earlier for tonsteins from Upper Silesia Coal Basin area. Additionally, minerals present in the tonsteins include kaolinite, quartz, kaolinitised biotite and feldspars. The presence of the phosphatic minerals apatite and goyazite has been recognized. The presence of gorceixite and crandallite is also possible. The contents of CaO (5.66 wt%) and P2O5 (6.2 wt%) are remarkably high. Analysis of selected trace elements demonstrated high contents of Sr (4937 ppm) and Ba (4300 ppm), related to the phosphatic minerals. On the basis of mineral composition the tonstein has been identified as a crystalline tonstein, transitional to a multiplied one.

scholarly journals Cooperative Control Mechanism of Long Flexible Bolts and Blasting Pressure Relief in Hard Roof Roadways of Extra-Thick Coal Seams: A Case Study

2021 ◽  
Vol 11 (9) ◽  
pp. 4125
Author(s):  
Zhe Xiang ◽  
Nong Zhang ◽  
Zhengzheng Xie ◽  
Feng Guo ◽  
Chenghao Zhang
Keyword(s):  
Coal Seam ◽  
Cooperative Control ◽  
Field Tests ◽  
Surrounding Rock ◽  
Deep Hole ◽  
Coal Seams ◽  
Thick Coal Seam ◽  
Structure Damage ◽  
Hard Roof

The higher strength of a hard roof leads to higher coal pressure during coal mining, especially under extra-thick coal seam conditions. This study addresses the hard roof control problem for extra-thick coal seams using the air return roadway 4106 (AR 4106) of the Wenjiapo Coal Mine as a case study. A new surrounding rock control strategy is proposed, which mainly includes 44 m deep-hole pre-splitting blasting for stress releasing and flexible 4-m-long bolt for roof supporting. Based on the new support scheme, field tests were performed. The results show that roadway support failure in traditional scenarios is caused by insufficient bolt length and extensive rotary subsidence of the long cantilever beam of the hard roof. In the new proposed scheme, flexible 4-m-long bolts are shown to effectively restrain the initial expansion deformation of the top coal. The deflection of the rock beam anchored by the roof foundation are improved. Deep-hole pre-splitting blasting effectively reduces the cantilever distance of the “block B” of the voussoir beam structure. The stress environment of the roadway surrounding rock is optimized and anchorage structure damage is inhibited. The results provide insights regarding the safe control of roadway roofs under extra-thick coal seam conditions.

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