Gas Control Technology for Fully Mechanized Face of Outburst Coal Seam with Hard Roof during Initial Caving

2011 ◽  
Vol 347-353 ◽  
pp. 974-978
Author(s):  
Ju Gen Fu ◽  
Wei Wu ◽  
Gen Yong Hua
Keyword(s):  
Coal Seam ◽  
Shock Pressure ◽  
Control Technology ◽  
Large Area ◽  
Hard Roof ◽  
Working Face ◽  
Initial Release ◽  
Gob Area ◽  
Outburst Coal Seam ◽  
Presplit Blasting

In the fully mechanized working face, with working face forward, gob area become bigger and bigger, when the top area reach a certain span ,roof in gob suddenly cave, outspreading a large quantity of mine gas, easy to cause the gas overrun and gas accidents. In addition, shock pressure which is caused when large area roof cave, easily causing casualties and damage of equipment. This paper introduces Pan three Coal mine 17171(1) ore advance of fully mechanized working face presplit blasting, rotating stoping and comprehensive extraction technologies, which successfully solve the roof management and the gas problems during initial release, achieving good security benefits.

scholarly journals Comprehensive technical support for safe mining in ultra-close coal seams: A case study

2021 ◽  
pp. 014459872110093
Author(s):  
Wei Zhang ◽  
Jiawei Guo ◽  
Kaidi Xie ◽  
Jinming Wang ◽  
Liang Chen ◽  
...  
Keyword(s):  
Coal Seam ◽  
Technical Support ◽  
Surrounding Rock ◽  
Coal Seams ◽  
Deformation Control ◽  
Hard Roof ◽  
Working Face ◽  
Close Coal Seams ◽  
Safe Mining

In order to mine the coal seam under super-thick hard roof, improve the utilization rate of resources and prolong the remaining service life of the mine, a case study of the Gaozhuang Coal Mine in the Zaozhuang Mining Area has been performed in this paper. Based on the specific mining geological conditions of ultra-close coal seams (#3up and #3low coal seams), their joint systematic analysis has been performed, with the focus made in the following three aspects: (i) prevention of rock burst under super-thick hard roof, (ii) deformation control of surrounding rock of roadways in the lower coal seam, and (iii) fire prevention in the goaf of working face. Given the strong bursting tendency observed in upper coal seam and lower coal seam, the technology of preventing rock burst under super-thick hard roof was proposed, which involved setting of narrow section coal pillars to protect roadways and interleaving layout of working faces. The specific supporting scheme of surrounding rock of roadways in the #3low1101 working face was determined, and the grouting reinforcement method of local fractured zones through Marithan was further proposed, to ensure the deformation control of surrounding rock of roadways in lower coal seams. The proposed fire prevention technology envisaged goaf grouting and spraying to plug leaks, which reduced the hazard of spontaneous combustion of residual coals in mined ultra-close coal seams. The technical and economic improvements with a direct economic benefit of 5.55 million yuan were achieved by the application of the proposed comprehensive technical support. The research results obtained provide a theoretical guidance and technical support of safe mining strategies of close coal seams in other mining areas.

Experimental Study on Deep Borehole Pre-Cracking Blasting of Drilling through Strata at Low Permeability Seam

2013 ◽  
Vol 868 ◽  
pp. 339-342
Author(s):  
Jian Liu ◽  
Qian Le
Keyword(s):  
Coal Seam ◽  
Control Area ◽  
Low Permeability ◽  
Gas Extraction ◽  
Test Results ◽  
Deep Borehole ◽  
Coal Seam Gas ◽  
Gas Concentration ◽  
Working Face ◽  
Outburst Coal Seam

In the process of roadway excavation in the low permeability outburst coal seam, with drilling through strata in the bottom drainage roadway extracting coal seam gas of control area. In order to improve extraction effect, the method that deep borehole pre-cracking blasting is used to increase the permeability of coal in the drilling through strata seam segment is proposed. The calculation formula on crushing circle and crack circle radius of deep borehole pre-cracking blasting are derived, and the effective loosening radius of blasting is calculated in theory, the research achievements are applied to field test, the test results show that deep borehole pre-cracking blasting permeability improvement technology is carried out in the drilling through strata of the low permeability outburst coal seam, the permeability of coal seam is improved by 180 times, the gas extraction scalar is raised by 8-10 tomes, during the process of roadway excavation, gas concentration of the working face is 0.2%-0.3%, and tunneling footage is increased by 2 times.

Study on Technology of Fully-Mechanized Sub-Level Caving Mining Technology in the Datong Permo Carboniferous Coal Seam

2012 ◽  
Vol 616-618 ◽  
pp. 565-568
Author(s):  
Bin Yu ◽  
Jun Zhao ◽  
Hong Chun Xia
Keyword(s):  
Coal Seam ◽  
Mining Area ◽  
Hard Coal ◽  
Control Technology ◽  
Mining Technology ◽  
Hard Roof ◽  
Sublevel Caving ◽  
Seam Mining ◽  
Longwall Top Coal Caving ◽  
And Control

This thesis briefly introduced roof control technology in fully-mechanized sublevel caving mining with hard roof and hard coal seam, Mining technology , gas prevention and comprehensive prevention and control technology in spontaneous combustion of coal, which in longwall top-coal caving face with hydraulic support in thickness seam in the Datong permo carboniferous coal seam . New development directions of fully-mechanized sublevel caving mining technology in the Datong mining area in the next few years.

scholarly journals Analysis of Overlying Strata Movement and Disaster-Causing Effects of Coal Mining Face under the Action of Hard Thick Magmatic Rock

Processes ◽  
2018 ◽  
Vol 6 (9) ◽  
pp. 150 ◽  
Author(s):  
Quanlin Wu ◽  
Quansen Wu ◽  
Yanchao Xue ◽  
Peng Kong ◽  
Bin Gong
Keyword(s):  
Coal Seam ◽  
Fracture Zone ◽  
Magmatic Rock ◽  
Ratio Test ◽  
Large Area ◽  
Deformation And Failure ◽  
Key Strata ◽  
Magmatic Rocks ◽  
Working Face ◽  
Bed Separation

When the hard and thick key strata are located above the working face, the bed separation structure is easy to be formed after mining because of the high strength and integrity of the hard and thick key strata and the initial breaking step is large. After the hard, thick strata are broken, the overburden will be largely collapsed and unstable in a large area and the dynamic disaster is easily induced. In this study, considering the fundamental deformation and failure effect of coal seam, the development law of the bed separation and the fractures under hard and thick magmatic rocks and the mechanism of breaking induced disaster of hard and thick magmatic rocks are studied by similar simulation tests. The results of the study are as follows: (1) The similar material ratio of coal seam is obtained by low-strength orthogonal ratio test of similar materials of coal seam, that is, cement:sand:water:activated carbon:coal = 6:6:7:1.1:79.9. (2) The magmatic rocks play a role in shielding the development of the bed separation, which makes the bed separation beneath the magmatic rock in an unclosed state for a long time, providing space for the accumulation of gas and water. (3) The distribution pattern of the fracture zone shows different shapes as the advancing of working face and the fracture zone width of the rear of working face coal wall is larger than that of the front of the open-off. (4) The breaking of magmatic rocks will press the gas and water accumulated in the bed separation space below to rush towards the working face along the fracture zone at both ends of the goaf. The above results are verified through the drainage borehole gas jet accident in the Yangliu coal mine. The research results are of great significance for revealing the occurrence process of dynamic disasters and adopting scientific and reasonable preventive measures.

Dynamic Disaster Forecasting Technology of the Island Working Face in Outburst Coal Seam

2014 ◽  
Vol 962-965 ◽  
pp. 914-918
Author(s):  
Rong Xi Shen ◽  
En Yuan Wang ◽  
Shao Bin Hu ◽  
Jun Jun Feng
Keyword(s):  
Coal Seam ◽  
Electromagnetic Radiation ◽  
Gas Content ◽  
Ratio Method ◽  
Safety Level ◽  
Gas Concentration ◽  
Working Face ◽  
Dynamic Disaster ◽  
Outburst Coal Seam ◽  
Hydraulic Supports

Coal and gas outburst and rock burst are the main threats of the island working face in outburst coal seam. According to the characteristic of No. 11061 island face in outburst coal seam, Liangbei coal mine, China, the dynamic disaster mechanism of island working face in outburst coal seam was analyzed. Based on the monitor of gas concentration and electromagnetic radiation and hydraulic supports resistance in the 11061 island face, the comprehensive forecasting technology of the island face in outburst coal seam was built, then the critical values of gas concentration and electromagnetic radiation and hydraulic supports resistance are calculated by three-ratio method. Finally, the comprehensive forecasting technology is used in the island working face. The results show that the combined action of gas content and stress induces the dynamic disaster of the island working face in outburst coal seam, and the comprehensive forecasting technology can forecast accurately dynamic disaster in the 11061 island face, which has brought successful engineering experience and distinct economic benefit. It can improve significantly the mine production safety level to research the forecasting technology of the island working face in outburst coal seam.

Analysis of Weighting over Great Extent upon Fully Mechanized Coal Face with Non-Hard Roof Based on Measured Data

2014 ◽  
Vol 962-965 ◽  
pp. 992-997
Author(s):  
Tao Zhu
Keyword(s):  
Experimental Analysis ◽  
Safety Valve ◽  
Measured Data ◽  
Large Area ◽  
Coal Face ◽  
Hydraulic Support ◽  
Mining Technology ◽  
Hard Roof ◽  
Drawing Speed ◽  
Working Face

Due to the influence of geology, mining technology, supporting strength, fully mechanized coal face sometimes would happen large area caving and weighting over great extent, causing casualties. Theoretical and experimental analysis shows, not only hard roof could happen weighting over great extent, but softer roof upon long wall face could happen, the only difference was the location of disaster and the failure forms. The paper analyzed weighting over great extent upon fully mechanized coal face with non-hard roof based on measured data. The results show that, the important factors of support break-off were the setting load of hydraulic support, drawing speed of working face and support efficiency, and it would achieve support break-off warning help to analyze the open rates of safety valve.

scholarly journals An Innovative Method for Placement of Gangue Backfilling Material in Steep Underground Coal Mines

Minerals ◽  
2019 ◽  
Vol 9 (2) ◽  
pp. 107 ◽  
Author(s):  
Yanchun Yin ◽  
Tongbin Zhao ◽  
Yubao Zhang ◽  
Yunliang Tan ◽  
Yue Qiu ◽  
...  
Keyword(s):  
Coal Seam ◽  
Large Scale ◽  
Small Scale ◽  
Underground Coal Mining ◽  
Long Distance ◽  
Subsidence Area ◽  
Working Face ◽  
Underground Coal Mines ◽  
Gob Area ◽  
Gangue Backfilling

Using gangue backfilling in underground coal mining not only controls the roof deformation in the gob area but also reduces the amount of mining waste rock. However, due to the limitations of the complicated engineering conditions, backfilling mining in the steep coal seam is not widely applied. In this study, a long-distance backfilling technology with a scraper winch for a steep coal seam was proposed and applied in a flexible shield supporting working face in Datai Mine, Beijing. Aiming at the problem of the decreasing backfilling ratio in field practice, numerical simulation was carried out to research the moving law of gangue in the goaf. The gangue mainly experienced four stages: gangue landslide stage, small-scale subsidence stage, funnel-shaped subsidence stage, and large-scale subsidence stage. The moving area of the gangue could be divided into five areas including a motionless area, a landslide area, a subsidence area, a funnel-shaped subsidence area, and a to-be-backfilled area. With the increase of the inclined length of the working face, the moving time of the gangue increased gradually. Based on the simulation results, the scheme of backfilling and mining in Datai Mine was optimized, for which the inclined length of the working face was shortened, and a higher backfilling ratio was obtained.

scholarly journals In Situ Studies on the Characteristics of Strata Structures and Behaviors in Mining of a Thick Coal Seam with Hard Roofs

Energies ◽  
2018 ◽  
Vol 11 (9) ◽  
pp. 2470 ◽  
Author(s):  
Yiwen Lan ◽  
Rui Gao ◽  
Bin Yu ◽  
Xiangbin Meng
Keyword(s):  
Coal Seam ◽  
Cantilever Beam ◽  
Layer Structure ◽  
Test Method ◽  
Thick Coal Seam ◽  
Hard Roof ◽  
Working Face ◽  
High Layer ◽  
Seam Mining

The movements of overburden induced by mining a thick coal seam with a hard roof extend widely. The effects of breakages in the hard strata on the strata behaviors might vary with the overlying strata layers. For this reason, we applied a test method that integrated a borehole TV tester, borehole-based monitoring of strata movement, and monitoring of support resistance for an in situ investigation of a super-thick, 14–20 m coal seam mining in the Datong mining area in China. The results showed that the range of the overburden movement was significantly high, which could reach to more than 300 m. The key strata (KS) in the lower layer main roof were broken into a ‘cantilever beam and voussoir beam’ structure. This structure accounted for the ‘long duration and short duration’ strata behaviors in the working face. On the other hand, the hard KS in the upper layer broke into a ‘high layer structure’. The structural instability induced intensive and wide-ranging strata behaviors that lasted for a long time (two to three days). Support in the working face were over-pressured by large dynamic factors and were widely crushed, while the roadways were violently deformed. Hence, the structure of a thick coal seam with a hard roof after mining will form a ‘cantilever beam and voussoir beam and high layer structure’, which is unique to a large space stope.

scholarly journals Prevention Technology for Strong Mine Pressure Disaster in the Hard-Roof Large-Mining-Height Working Face

2020 ◽  
Vol 2020 ◽  
pp. 1-15
Author(s):  
Hongfei Duan ◽  
Lijuan Zhao
Keyword(s):  
Hydraulic Fracturing ◽  
Hard Rock ◽  
Mine Pressure ◽  
Overburden Rock ◽  
Large Area ◽  
Rock Stratum ◽  
Hard Roof ◽  
Working Face ◽  
Large Mining Height ◽  
Mining Height

The movement and destruction of the hard roof in a stope is an important reason for the occurrence of strong ground pressure disasters at the working face. Considering Tongxin Coal Mine as the engineering background, the stress distribution law of the surrounding rock and the overburden rock damage characteristics of a large-mining-height working face under the hard roof were investigated. To solve the problem whereby the stope’s hard roof is difficult to collapse, the hard rock key stratum of the roof was hydraulically fractured to weaken the mechanical properties of the roof rock stratum. Additionally, microseismic monitoring technology was used to monitor the cracking effect of the rock stratum. The theoretical calculation and numerical simulation results reveal that, after hydraulic fracturing, a crack with a more consistent trend formed inside the hard rock stratum and a large area of the rock stratum was damaged. According to the monitoring results of the stope stress after hydraulic fracturing, the law governing the occurrence of the leading bearing pressure was in effect. In contrast, the influence range and peak strength of the leading bearing pressure were considerably reduced at the working face after hydraulic fracturing. After performing hydraulic fracturing on the roof of the working face, the bearing pressure of the working face can satisfy the production requirements better. Finally, the results obtained through this study can be used as a reference for determining the width of coal pillars under similar mining conditions.

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