scholarly journals The Sustainable Development of Aged Coal Mine Achieved by Recovering Pillar-Blocked Coal Resources

Energies ◽  
2020 ◽  
Vol 13 (15) ◽  
pp. 3912
Author(s):  
Huadong Gao ◽  
Baifu An ◽  
Zhen Han ◽  
Yachao Guo ◽  
Zeyu Ruan ◽  
...  
Keyword(s):  
Coal Mine ◽  
Coal Pillar ◽  
Economic Benefits ◽  
Industrial Facilities ◽  
The Sustainable Development ◽  
Coal Resources ◽  
Coal Pillars ◽  
Social Environmental ◽  
Residual Coal ◽  
China’S Economy

China faces the problem of depletion of its coal resources, and a large number of mines are becoming aged mines. Demand for coal, however, still increases due to the growth of China’s economy. Energy shortage might restrict the sustainability of China’s national economy. As one contribution to a solution, this paper proposes the innovative exploitation method of solid backfill coal mining (SBCM) technology to exploit parts of pillar-blocked (residual coal pillar resources under industrial square, RCPRIS) that protect industrial facilities. Thus, blocked coal resources may be converted into mineable reserves that improve the recovery ratio of mine resources. Also, waste would be removed from the surface reducing hazards of environmental pollution. Based on the case of the Baishan Coal Mine in Anhui, China, numerical simulation is used to study the size of shaft-protecting coal pillars (SPCP) required at different backfill ratios. Results show that the disturbance to a shaft caused by exploitation decreases with the increase of the backfill ratio. When using SBCM to exploit RCPRIS under the condition of 80% backfill ratio, compared with the caving method, a lot of pillar-blocked coal resources would be freed. The life of Baishan Coal Mine would be prolonged, resulting in appreciable social, environmental, and economic benefits.

scholarly journals Study on Stress Relief of Hard Roof Based on Presplitting and Deep Hole Blasting

2020 ◽  
Vol 2020 ◽  
pp. 1-12
Author(s):  
Peng Gong ◽  
Yongheng Chen ◽  
Zhanguo Ma ◽  
Shixing Cheng
Keyword(s):  
Stress Distribution ◽  
Coal Mine ◽  
Coal Pillar ◽  
Deep Hole ◽  
Hard Roof ◽  
Formation Conditions ◽  
Coal Pillars ◽  
Mining Coal ◽  
The Impact ◽  
Pillar Size

For the problem that the hard roof causes wider end-mining coal pillar, and the roadway is greatly affected by mining, this paper took Shanxi Luning Coal Mine as the engineering background; based on the stress distribution characteristics of the coal pillar, the calculation method of the limit end-mining coal pillar size was given; considering the formation conditions and transmission forms of the advanced abutment stress, a method combining presplitting and deep hole blasting was proposed to weaken the advanced abutment stress. The numerical simulation was used to analyze the stress distribution of coal pillars, which was verified by on-site industrial tests. The results showed that the presplitting can achieve the blocking of stress. The closer it is to the peak of the abutment stress, the better the blocking effect. Deep hole blasting can weaken the source of the advanced abutment stress and reduce the peak of abutment stress. With the combination of the two blasting methods, the end-mining coal pillar size of Luning Coal Mine can be reduced to 60 m. The method combining presplitting and deep hole blasting can effectively reduce the end-mining coal pillar size and reduce the impact of mining on the deformation of the dip roadway.

Microseismic Precursory Characteristics of Rock Burst Hazard in Mining Areas Near a Large Residual Coal Pillar: A Case Study from Xuzhuang Coal Mine, Xuzhou, China

2016 ◽  
Vol 49 (11) ◽  
pp. 4407-4422 ◽  
Author(s):  
An-ye Cao ◽  
Lin-ming Dou ◽  
Chang-bin Wang ◽  
Xiao-xiao Yao ◽  
Jing-yuan Dong ◽  
...  
Keyword(s):  
Rock Burst ◽  
Coal Mine ◽  
Coal Pillar ◽  
Mining Areas ◽  
Burst Hazard ◽  
Residual Coal

Optimization Studies on Pillar Size of Fully Mechanized Caving Face

2014 ◽  
Vol 1010-1012 ◽  
pp. 1535-1539
Author(s):  
Xian Zhi Meng
Keyword(s):  
Numerical Simulation ◽  
Stress Distribution ◽  
Theoretical Calculations ◽  
Coal Pillar ◽  
Economic Benefits ◽  
Monitoring Methods ◽  
Coal Resources ◽  
Roadway Stability ◽  
Extent Of Damage ◽  
Pillar Size

By theoretical calculations, numerical simulation and field monitoring methods to analyze the stress distribution and the extent of damage of coal pillar determine a reasonable size is about 10m, can improve the recovery rate of coal resources, and to ensure the roadway stability. 10m pillar coal resources compared with the previous 20m pillar recovery increased by about 5.5%, and created tremendous economic benefits of the mine.

scholarly journals Mechanism of Coal Burst and Prevention Practice in Deep Asymmetric Isolated Coal Pillar: A Case Study from YaoQiao Coal Mine

2021 ◽  
Vol 2021 ◽  
pp. 1-19
Author(s):  
Chengchun Xue ◽  
Anye Cao ◽  
Wenhao Guo ◽  
Songwei Wang ◽  
Yaoqi Liu ◽  
...  
Keyword(s):  
Numerical Simulation ◽  
Coal Mine ◽  
Prevention And Control ◽  
High Stress ◽  
Coal Pillar ◽  
Support Pressure ◽  
Mining District ◽  
Coal Pillars ◽  
And Control ◽  
The Impact

Coal pillar bursts continue to be a severe dynamic hazard. Understanding its mechanism is of paramount importance and crucial in preventing and controlling its occurrence. The extreme roadway deformations from the asymmetric isolated coal pillars in the central mining district of YaoQiao Coal Mine have responded with frequent intense tremors, with risky isolated coal pillar bursts. The theoretical analysis, numerical simulation, and field measurements were done to research the impact of spatial overburden structure and stress distribution characteristics on the isolated coal pillar area, aiming to reveal the mechanism of coal pillar burst leading to the practice of prevention and control in the asymmetric isolated coal pillar area. The study shows that the overburden structure of the asymmetric is an asymmetric “T” structure in the strike-profile, and the stress in the coal pillar is mostly asymmetric “saddle-shaped” distribution, with the peak stress in the east side of the coal pillar, and the coal pillar is a “high stress serrated isolated coal pillar.” Numerical simulation results showed that the support pressure in the isolated coal pillar area on the strike profile was asymmetrically “saddle-shaped” distribution. The peak vertical stress in the coal pillar area continued to rise and gradually shifted to the mining district's deep part. As a result, the response of the roadway sides to the dynamic load disturbance was more pronounced. They developed a coal burst prevention and control program of deep-hole blasting in the roof of asymmetrical isolated coal pillar roof and unloading pressure from coal seam borehole. Monitored data confirmed that the stress concentration was influential in the roadway’s surrounding rock in the asymmetric isolated coal pillar area, circumventing coal pillar burst accidents. The research outcomes reference the prevention and control of coal bursts at isolated working faces of coal pillars under similar conditions.

scholarly journals Reasonable coal pillar design and remote control mining technology for highwall residual coal resources

2019 ◽  
Vol 6 (4) ◽  
pp. 181817 ◽  
Author(s):  
Fangtian Wang ◽  
Cun Zhang
Keyword(s):  
Remote Control ◽  
Coal Pillar ◽  
Open Pit Mine ◽  
Open Pit ◽  
Recovery Ratio ◽  
Coal Resources ◽  
The Road ◽  
Highwall Mining ◽  
Geological Conditions ◽  
Residual Coal

Highwall mining (HWM) technology is an efficient method for exploiting residual coal resources in Chinese open-pit coal mines. However, on-site personnel and equipment can be damaged by the instability of the highwall mining residual coal pillars and subsidence of final end-walls. This paper considers the geological conditions of an open-pit mine in Shendong Coal Field (China) in order to prevent overlying rock fall accidents; the Mark-Bieniawski formula and the FLAC3D numerical simulation are used to analyse reasonable coal pillar widths outside and under the road, which were determined to be 1.7 m and 1.3 m, respectively. Using the EBH132 cantilever excavator for remote control mining, the field experiment shows that the recovery ratio of highwall residual coal resources was over 67%; hence, safety, efficiency and high recovery ratio of highwall mining were achieved for the residual coal resources of an open-pit mine.

scholarly journals Determination of fracture location of double-sided directional fracturing pressure relief for hard roof of large upper goaf-side coal pillars

2019 ◽  
Vol 38 (1) ◽  
pp. 111-136 ◽  
Author(s):  
Jiangwei Liu ◽  
Changyou Liu ◽  
Xuehua Li
Keyword(s):  
Hydraulic Fracturing ◽  
Coal Mine ◽  
High Stress ◽  
Coal Pillar ◽  
Local Stress ◽  
Pressure Relief ◽  
Directional Hydraulic Fracturing ◽  
Fracture Location ◽  
Hard Roof ◽  
Coal Pillars

After mining the upper-goaf side, large coal pillars and part of hard roof exposed above the pillars remain. The hard roof can significantly deform the roadway by transferring high stress through coal pillars to the roadway. This paper reports the use of hydraulic fracturing technology to cut the hard roof on both sides (i.e. the broken roof slides to the goaf) to relieve the pressure. The position of the roof fracture is the key to controlling the pressure relief. The bearing characteristics of the large coal pillars and hard roof are analyzed to establish a mechanical model of the broken-roof sliding instability after directional fracturing and determine the width of the coal pillars that can collapse under maximum overburden load on coal pillars as a reasonable hydraulic fracturing position. The results show that the distance from the mine gateway to the fracture location increases with increasing hard-roof length, coal pillar depth, coal pillar thickness (mining height), and goaf width. In addition, the distance to the mine gateway decreases with increasing coal strength, support of the coal pillar by the anchor rod, cohesive force, and internal friction angle of the coal–rock interface. Engineering tests were applied in coal roadway 5107 of coal seam 5# of the Baidong Coal Mine of the Datong Coal Mine Group. Given the site conditions, a reasonable fracturing length of 8.8 m was obtained. Next, directional hydraulic fracturing was implemented. The comparison of the roof deformation before and after fracturing suggests that this method reduces the local stress concentration in coal pillars, which allows the surrounding rock deformation in roadway 5107 to be controlled.

Experimental Study on Double Truss Cable Supporting System of Coal Roadways in the Isolated Coal Pillar and Fold Region

2012 ◽  
Vol 214 ◽  
pp. 296-300
Author(s):  
Hong Yan ◽  
Teng Fei Xu ◽  
Yang Li
Keyword(s):  
Experimental Study ◽  
Coal Pillar ◽  
Coal Roadway ◽  
Roadway Safety ◽  
Underground Coal Mines ◽  
Supporting Effect ◽  
Coal Resource ◽  
Coal Pillars ◽  
Residual Coal ◽  
The Relationship

The gangue in parts of underground coal mines in China is not to be hoisted to ground for direct accumulation but replace the coal resource in larger residual coal pillars. In order to solve the supporting problem of roadways in the isolated coal pillar and tectonic region, we firstly research the relationship between the supporting effect and fold or isolated coal pillar factor. Based on the analyzing results, the double truss cable support system (DTCSS) is proposed, and then the corresponding support structure and superiority are studied. Finally, a typical complex coal roadway affected by factors of synclinal axes, isolated coal pillar and intersection with another roadway was experimented using DTCSS, and the monitoring results of the roadway displacement showed that both of the largest roof subsidence and the convergence of both sides were no more than 170mm, which ensured the roadway safety and proved the efficiency of the DTCSS.

scholarly journals Risk Assessment and Control Strategy of Residual Coal Pillar in Room Mining: Case Study in Ecologically Fragile Mining Areas, China

2021 ◽  
Vol 13 (5) ◽  
pp. 2712
Author(s):  
Hengfeng Liu ◽  
Qiang Sun ◽  
Nan Zhou ◽  
Zhongya Wu
Keyword(s):  
Coal Pillar ◽  
Stability Control ◽  
Mining Areas ◽  
Long Term Stability ◽  
Movement Characteristics ◽  
Coal Pillars ◽  
The Stability ◽  
Residual Coal ◽  
Mining Coal ◽  
And Control

Gradual instability of coal pillars left behind underground with room mining is one of the main reasons for sudden roof caving in the gob, surface subsidence, and other significant hazards. Moreover, room mining implies great losses of coal resources. In this paper, the main failure mode and room mining coal pillar process were analyzed according to the coalfield regional engineering geological and hydrogeological conditions. A numerical model was adopted to study the effect of different sizes of coal mining pillars and progressive instability failure of coal pillar on the plastic zone’s evolution characteristics and stress field of coal pillars in the stope. The proposed technologies of cemented paste backfilling and reinforcement of residual coal pillars are applied, and a numerical simulation model is established to study the strata movement characteristics and analyze the stability degree of residual coal pillar and key aquiclude strata in the Pliocene series of Neogene. Consequently, the performance and application prospect were evaluated. The results obtained substantiate a new method for the long-term stability control of coal pillars in room mining and protecting the ecological environment in China’s western eco-environmental frangible area.

Study of Feasibility and Technology of Recleaning Middlings of Coking Coal

2011 ◽  
Vol 361-363 ◽  
pp. 301-304 ◽  
Author(s):  
Xiu Ming Hu ◽  
Rui Chen Ren ◽  
Cai Xia Li
Keyword(s):  
Froth Flotation ◽  
Economic Benefits ◽  
Size Analysis ◽  
Separation Processes ◽  
Coking Coal ◽  
The Sustainable Development ◽  
Coal Resources ◽  
The Status ◽  
Environmental Requirements ◽  
Preparation Plant

The status of coking coal resources and the utilization of the middlings of coking coal are analyzed in this paper, and the necessity and practicability of middlings’ rewashing is held up. Middlings of BaBao Industrial Park Coal Preparation Plant is used as sample of experiment test, through size analysis and float-and-sink test, the feasibility of middlings’ rewash is demonstrated. Two kindes of separation processes are presented : ⑴crushing-coarse and thin slime are separated separately; ⑵crushing-grinding-froth flotation. Scheme 2 is appropriate for the separation of Babao middings.Experiments confirm that the scheme 2 would be more suitable for the middlings’ separation, and the cleaned coal’s production rate of is 31.88% , the ash content is 14.4%. So there are high social benefits and economic benefits. Reclean middlings of coking coal is a new direction for the protection of coking coal resources, in the meantime, it comply with the environmental requirements and is an important measure to realize the sustainable development.

scholarly journals Destabilization and energy characteristics of coal pillar in roadway driving along gob based on rockburst risk assessment

2019 ◽  
Vol 6 (7) ◽  
pp. 190094 ◽  
Author(s):  
Yi Xue ◽  
Zhengzheng Cao ◽  
Wenlong Shen
Keyword(s):  
Mathematical Model ◽  
Mechanical System ◽  
Rock Burst ◽  
Research Result ◽  
Coal Pillar ◽  
Peak Stress ◽  
Observation Data ◽  
The Sustainable Development ◽  
Coal Pillars ◽  
Energy Accumulation And Dissipation

Roadway driving along adjacent goafs is an effective method to develop the recovery rate of coal resources. However, rock burst triggered by dynamic destabilization of coal pillars poses a serious threat to safe and efficient mining, thereby significantly restricting the sustainable development of coal mines. In this study, from the perspectives of energy accumulation and dissipation, a mathematical model of coal pillars is established and the energy equilibrium relationship of the mechanical system is analysed. The rock burst mechanism of coal pillars in gob-side entry is obtained based on a fold catastrophe mathematical model. Results indicate that the rock burst triggered by the instability is a destabilization phenomenon. If the stiffness factor of the mechanical system is less than 1 and the external force is enough to lead coal pillars to the peak stress point, then rock burst disaster occurs. The engineering analysis and numerical simulation are conducted to study the rock burst in the gob-side entry that occurred in Xin'an coal mine. Stress release caused by mining can reduce the risk of rock burst to a certain extent. The amount of elastic energy released is 6.4512 × 10 7 J, which is close to the observation data and verifies the correctness and rationality of the research method. The research result provides a theoretical basis and technical guidance for rock burst prevention and control in roadway driving along adjacent goafs.

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