A Sequential Approach for Integrated Coal and Gas Mining of Closely-Spaced Outburst Coal Seams: Results from a Case Study Including Mine Safety Improvements and Greenhouse Gas Reductions

Liang Cheng, Zhaolong Ge, Jiufu Chen, Hao Ding, Lishuang Zou and Ke Li
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Liang Cheng: China Merchants Chongqing Communications Technology Research & Design Institute Co., Ltd., Chongqing 400067, China
Zhaolong Ge: State Key Laboratory of Coal Mine Disaster Dynamics and and Control, Chongqing University, Chongqing 400044, China
Jiufu Chen: Chongqing Energy Investment Group, Chongqing 400060, China
Hao Ding: China Merchants Chongqing Communications Technology Research & Design Institute Co., Ltd., Chongqing 400067, China
Lishuang Zou: Chongqing Energy Investment Group, Chongqing 400060, China
Ke Li: National Engineering Laboratory for Highway Tunnel Construction Technology, Chongqing 40067, China

Energies, 2018, vol. 11, issue 11, 1-16

Abstract: Closely-spaced outburst coal seams (COCS) is the main condition of coal seams in southwest China, and gas disasters are one of the major problems affecting coal mine safety. Mining a protective seam and pre gas extraction are the most safety way to improve the efficiency of mining under these conditions. However, low pre-mining gas extraction efficiency coupled with the close proximity of adjacent working faces is a problem. When mining at an old working face has been completed but the new working face is not yet ready to be mined, coal-bed gasses can flow into the new working face from adjacent seams and this commonly causes methane monitoring instruments to sound an alarm. These gas extraction difficulties lead to a conflict between mine safety and profit. To solve these problems, a sequential approach for integrated coal and gas mining of closely-spaced outburst coal seams is introduced in this paper. Two fundamental principles are proposed: (1) Fully coordinating the spatiotemporal relationships between gas extraction, roadway development, and coal mining to maximize both mine safety and coal and gas production; (2) Defining a mining sequence for outburst coal seams and choosing the coal seam with the weakest outburst risk as the protective seam. A system for comprehensive gas extraction in underground coal mines is divided into four stages for gas extraction: gas extraction before coal roadway tunneling, gas extraction before coal mining, gas extraction during coal mining, and gas extraction from the goaf after coal mining. The Songzao mining area, China, is used as a case study to demonstrate the effectiveness of this model, and it brings three major benefits: it improves underground coal mine safety with physical gas accidents decreased by 66.8%, it makes underground coal-bed methane (CBM) extraction more efficient with the average gas extraction rate were respectively 45.13 m3/t and 62.4%, the highest in China, and it reduces greenhouse gas emissions equivalent to 3.5 million tonnes of carbon dioxide. This study could be used as a valuable example for other coal deposits being mined under similar geological conditions.

Keywords: outburst coal seam; gas disaster; coal mining; gas extraction; greenhouse gas (search for similar items in EconPapers)
JEL-codes: Q Q0 Q4 Q40 Q41 Q42 Q43 Q47 Q48 Q49 (search for similar items in EconPapers)
Date: 2018
References: View references in EconPapers View complete reference list from CitEc
Citations: View citations in EconPapers (6)

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