Theoretical and technological exploration of deep in situ fluidized coal mining

2019 ◽  
Vol 13 (4) ◽  
pp. 603-611 ◽  
Author(s):  
Heping Xie ◽  
Yang Ju ◽  
Shihua Ren ◽  
Feng Gao ◽  
Jianzhong Liu ◽  
...  
Keyword(s):  
Coal Mining ◽  
Technological Exploration

scholarly journals Cutting Resistance Laboratory Testing Methodology for Underwater Coal Mining

Minerals ◽  
2021 ◽  
Vol 11 (6) ◽  
pp. 564
Author(s):  
Vladimir Čebašek ◽  
Veljko Rupar ◽  
Stevan Đenadić ◽  
Filip Miletić
Keyword(s):  
Coal Mining ◽  
Laboratory Testing ◽  
Water Pressure ◽  
Laboratory Data ◽  
Working Environment ◽  
Laboratory Research ◽  
Surrounding Water ◽  
Cutting Resistance ◽  
Testing Methodology

The bucket-wheel dredge “Kovin I” for underwater coal mining with bucket-wheel type UCW-450 has been in operation for over 20 years. Based on analyzing the bucket-wheel dredger performance, productivity, maintenance costs, and reliability, a rational decision was made: to rehabilitate the most essential parts of the dredge, including the bucket wheel and the gearbox. However, the selection and construction of the excavator parts were performed on the ground of available laboratory data for digging resistance. The data itself was determined by the testing methodology that did not include the influence of surrounding water pressure at a certain depth of mining. According to the previous findings, it was necessary to develop a specific research and testing program that would involve appropriate laboratory testing of the geomechanical parameters. These were to represent the influence of hydrostatic water pressure on the working environment—coal. Nevertheless, geomechanical laboratory research tests were initially modified to provide reliable data of cutting resistance, especially in the water under different hydrostatic pressures, fully simulating the “in situ” working conditions of mining, i.e., cutting.

Principle of Well-Net Design for Coalbed Methane Exploitation in Coal Mine Area

2014 ◽  
Vol 543-547 ◽  
pp. 3967-3973
Author(s):  
Bao Shan Han
Keyword(s):  
Coal Mining ◽  
Coal Mine ◽  
Coalbed Methane ◽  
Design Theory ◽  
Surface Condition ◽  
Coal Pillar ◽  
Negative Influence ◽  
In Situ Stress ◽  
Well Location

There are abundant CBM (Coalbed Methane) in China. These CBM has caused a remarkable problem to the coal-mining in China. In order to improve the structure of Chinese energy and eliminate the risk of coal mine gas, the relevant industries and sections have implemented many explorations in CBM enriched areas. With great achievements, there are many important problems in the actions of CBM exploitation. The disadvantageous interaction of the surface CBM well and the later coal mining has been ignored at all. There are many disadvantages and defects. To solve these problems and eliminate or weaken the disadvantageous, the scientific and reasonable design of surface CBM well location is an important step. With the thinking of surface condition, coal mining plan, the arrangement of coal mine laneway, the direction and scale of the in-situ stress, and thinking more about the negative influence to and of surface CBM well, according to the theories of mining dynamics, mining engineering, mining geomechanics, and the CBM engineering, the design theory of the surface CBM well net can be studied. Finally, the arrangement principle of CBM product well in coal field is presented. The existing or future coal pillar will be a critical location for the surface CBM well location.

scholarly journals Research on the Disaster-Inducing Mechanism of Coal-Gas Outburst

2020 ◽  
Vol 2020 ◽  
pp. 1-12 ◽  
Author(s):  
Fengxiang Nie ◽  
Honglei Wang ◽  
Liming Qiu
Keyword(s):  
Coal Mining ◽  
In Situ Stress ◽  
Gas Pressure ◽  
Underground Coal Mining ◽  
Coal Gas ◽  
Gas Outburst ◽  
Mining Depth ◽  
Mining Coal ◽  
Occurrence Mechanism

In China, coal-gas outburst is seriously affecting safety of the coal mine. To improve the safety status of underground coal mining, this work investigated the evolution process and occurrence mechanism of coal-gas outburst under the coupling action of stress and gas. Results show that increasing either gas pressure or in-situ stress can make coal destroy and destabilize, and the contribution of gas pressure to coal failure is twice that of in-situ stress. In ultradeep coal mining, coal-gas outburst may occur even under the condition of low gas pressure due to large in-situ stress. Moreover, the larger the mining depth is, the lower the gas index is required for disaster occurrence. The results have certain guiding significance for coal energy mining and the control of coal-gas outburst in deep coal mining.

Reduction of Metal Consumption in View of Mining Cutting Tools Operation

2015 ◽  
Vol 756 ◽  
pp. 144-149
Author(s):  
Sergey A. Prokopenko
Keyword(s):  
Coal Mining ◽  
High Efficiency ◽  
Cutting Tools ◽  
Rock Breaking ◽  
Economic Costs ◽  
In Situ Testing ◽  
Metal Consumption ◽  
The Common ◽  
High Level

Existing technologies of manufacturing and operation of picks at mining machines entail high level of metal waste and result in unreasonably high economic costs of engineering and coal mining industries. It is proposed to manufacture reusable picks with a changeable working part of the head. Contrary to the common beliefs the in situ testing confirmed the feasibility of using such picks for rock breaking, as well as their high efficiency.

scholarly journals Large Deformation Mechanics of Gob-Side Roadway and Its Controlling Methods in Deep Coal Mining: A Case Study

2020 ◽  
Vol 2020 ◽  
pp. 1-13
Author(s):  
Jianwei Zheng ◽  
Wenjun Ju ◽  
Xiaodong Sun ◽  
Zhongwei Li ◽  
Shuai Wang ◽  
...  
Keyword(s):  
Stress Field ◽  
Large Deformation ◽  
Coal Mining ◽  
Tectonic Stress ◽  
In Situ Stress ◽  
Field Analysis ◽  
Underground Mines ◽  
Roof Structure ◽  
Deformation Mechanics

Maintaining surrounding rock mass stability of roadways is essential to the safety of deep coal mining. In this study, the No. 2-2092 roadway of the No. 2-209 mining face in Ganhe coal was taken as the target roadway for field analysis. The selected region can be considered a typical area with dominating geological tectonic stress, based on the geological survey and in situ stress results. A mechanical model of roadway overburdens was developed to analyse the large deformation and stress field distribution. It is found that the large deformation is caused by the combined superposed stress field including laterally transferred stress formed in structures at overlying strata, mining-induced advanced abutment pressure, and the regional in situ stress. Thus, a Two-Direction Hydrofracturing Technique (TDHT) was proposed to reduce the pressure of the No. 2-2092 roadway by altering the roof structure in the influenced zones. Compared with the original roadway without fracturing, it is found that the roof to floor convergence has dropped by nearly 47% after fracturing; the displacement of sidewalls has reduced by almost 31%, demonstrating the effectiveness of the proposed method in pressure relief. Results from this study can provide guidance on controlling the large deformation of roadways in deep underground mines.

scholarly journals Study on Temporal and Spatial Characteristics of Overlying Strata in Deep Coal Mining Process

2021 ◽  
Author(s):  
Bang-an Zhang ◽  
Yang yushun ◽  
Dong-ming Zhang
Keyword(s):  
Stress Concentration ◽  
Coal Seam ◽  
Coal Mining ◽  
Three Dimensional ◽  
In Situ Stress ◽  
Three Dimensional Model ◽  
Concentration Coefficient ◽  
Working Face ◽  
Stress Concentration Coefficient

Abstract This paper adopts the stress relief method to test the in-situ stress in the field to obtain the in-situ stress distribution characteristics of No. 2+3# coal seam. A three-dimensional model was established with the No. S3012 working face as the engineering background, and the measured in-situ stress values ​​were applied to the three-dimensional model, and the spatial-temporal evolution characteristics of coal and rock mass around the stope during coal seam mining were studied. The specific conclusions are as follows: the three-dimensional stress distribution map in front of, behind and on both sides of the working face in the process of coal mining are obtained. As the working face goes on, the maximum value of the supporting stress formed in front of, behind and on both sides of the working face shifts to the corner, presenting a “hump-like” distribution. The stress concentration coefficient of front, back and both sides of stope increases linearly with the increase of mining size. Under the same mining size, the stress concentration coefficient in front of stope is the smallest, and the stress concentration coefficient on both sides is the largest. The three-dimensional displacement field distribution nephogram of overlying strata in the process of coal mining is obtained. With the continuous advance of the working face, the roof strata of coal seam undergo continuous dynamic subsidence process, and the roof subsidence increases continuously, showing the shape of "bowl" with sharp bottom. In the process of working face mining, the roof displacement of coal seam showed an "O" shape evolution characteristic. The three-dimensional distribution cloud map of the plastic zone of coal and rock mass in the process of working face mining was obtained, and the failure volume of the plastic zone gradually increases with the continuous progress of the working face.

scholarly journals The importance of in-situ conservation area in mining concession in preserving diversity, threatened and potential floras in East Kalimantan, Indonesia

2018 ◽  
Vol 20 (1) ◽  
pp. 198-210 ◽  
Author(s):  
ABBAN PUTRI FIQA ◽  
FAUZIAH FAUZIAH ◽  
DEWI AYU LESTARI ◽  
SUGENG BUDIHARTA
Keyword(s):  
Coal Mining ◽  
Conservation Status ◽  
In Situ Conservation ◽  
Mining Operation ◽  
Mining Area ◽  
Diversity Indices ◽  
Natural Forests ◽  
Conservation Area ◽  
East Kalimantan

Fiqa AP, Fauziah, Lestari DA, Budiharta S. 2019. The importance of in-situ conservation area in mining concession in preserving diversity, threatened and potential floras in East Kalimantan, Indonesia. Biodiversitas 20: 198-210. East Kalimantan is the most well-known province in Indonesia with high natural resources, particularly from the mining sector. While delivering benefits for economic development, coal mining operation negatively affects biodiversity. Effort to mitigate impacts on biodiversity is by establishing an in-situ conservation area inside the coal mining area. This area is preserved in the form of arboretum from existing natural forests. The aim of this research is to identify the importance of conservation area in a mining concession in East Kalimantan regarding its plants’ diversity, conservation status, and utilization. The research was conducted by doing vegetation analysis and inventorying plant biodiversity inside the in-situ conservation area by using plot samples. The result showed that the in-situ conservation area protects at least 142 species with a high level of biodiversity on all vegetation phases, indicated by Shannon Wiener diversity indices in which all phase have an index higher than 3. It protects 22 species listed in IUCN Red List of threatened species and contains at least 90 potential plants utilized by traditional Dayak people in their daily life. This study highlights that the conservation area is an important part in mining management to protect biodiversity, and suggest that in-situ conservation area should be preserved by every mining concession.

scholarly journals Gas Release Characteristics in Coal under Different Stresses and Their Impact on Outbursts

Energies ◽  
2018 ◽  
Vol 11 (10) ◽  
pp. 2661 ◽  
Author(s):  
Hanpeng Wang ◽  
Bing Zhang ◽  
Liang Yuan ◽  
Guofeng Yu ◽  
Wei Wang
Keyword(s):  
Theoretical Analysis ◽  
Coal Mining ◽  
Energy Analysis ◽  
In Situ Stress ◽  
Gas Release ◽  
Impact Mechanism ◽  
Fracture Development ◽  
The Impact ◽  
Different Gases

The impact mechanism of in situ stress on outbursts plays a key role in the prevention of outbursts during deep coal mining. The in situ stress may influence the outburst by affecting the gas release intensity according to theoretical analysis, but none of the existing studies have taken into consideration this perspective. To explore whether the influence of in situ stress on gas release in coal is an important reason for stress-induced outbursts, experiments on gas release in coal under different axial stresses and on exposure-induced outbursts with different gases were conducted to respectively study the influence of in situ stress on gas release and the impact of gas release on outburst. The results show that with the increase of stress, the methane release intensity rises by 1~2.4 times and shows an obvious periodicity due to different degrees of fracture development. A small increase in gas release intensity can lead to huge increase in the outburst intensity based on an energy analysis of the outburst experiments, indicating that the gas release intensity is a sensitive physical quantity that influences outbursts. The differences in gas release in coal with different stresses will result in differences in the outburst results based on data from the two experiments, proving that the change in gas release intensity during variations of in situ stress is an important factor for in situ stress-induced outbursts. The research achievements can enrich the impact mechanism of in situ stress on outbursts.

scholarly journals In Situ Test Study of Characteristics of Coal Mining Dynamic Load

2015 ◽  
Vol 2015 ◽  
pp. 1-8 ◽  
Author(s):  
Jiang He ◽  
Lin-Ming Dou ◽  
Wu Cai ◽  
Zhen-Lei Li ◽  
Yan-Lu Ding
Keyword(s):  
Strain Rate ◽  
Coal Mining ◽  
Stress Wave ◽  
Dynamic Load ◽  
Frequency Component ◽  
High Frequency Component ◽  
Stress Wave Propagation ◽  
Vibration Velocity ◽  
In Situ Test

Combination of coal mining dynamic load and high static stress can easily induce such dynamic disasters as rock burst, coal and gas outburst, roof fall, and water inrush. In order to obtain the characteristic parameters of mining dynamic load and dynamic mechanism of coal and rock, the stress wave theory is applied to derive the relation of mining dynamic load strain rate and stress wave parameters. The in situ test was applied to study the stress wave propagation law of coal mine dynamic load by using the SOS microseismic monitoring system. An evaluation method for mining dynamic load strain rate was proposed, and the statistical evaluation was carried out for the range of strain rate. The research results show that the loading strain rate of mining dynamic load is in direct proportion to the seismic frequency of coal-rock mass and particle peak vibration velocity and is in inverse proportion to wave velocity. The high-frequency component damps faster than the low-frequency component in the shockwave propagating process; and the peak particle vibration velocity has a power functional relationship with the transmitting distance. The loading strain rate of mining dynamic load is generally less than class 10−1/s.

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