Coal Pillar Extraction Under Weak Roof
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Coal Pillar Extraction Under Weak Roof Arun Kumar Singh 1 & Ashok Kumar 1 & Dheeraj Kumar 2 Rakesh Kumar 1 & Amit Kumar Singh 1
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Rajendra Singh 1
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Sahendra Ram 1
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Received: 1 April 2020 / Accepted: 23 July 2020 # Society for Mining, Metallurgy & Exploration Inc. 2020
Abstract This article offers an examination of a retreat mining method conducted at the Pinoura Mine in India from 2010 to 2017. The method is atypical for coal mines of India’s coalfields. The method executes depillaring in a single pass and does not require the formation of galleries and support installation in splits, thus, reducing the cycle time. A variety of observations are discussed throughout this work and emphasis is placed on field measurements and depillaring under weak roof (RMR = 40–45). This paper discusses design techniques, specifically the estimation of the snook (remnant pillar) size, and important practical observations after the fact. The execution of this method was eventually conducted in eleven panels. Keywords Mechanized depillaring . Single-pass pillar extraction . Weak roof . Roof fall . Snook
1 Introduction A mining method for pillar extraction was introduced at the Pinoura Mine in the South Eastern Coalfields Limited of Bilaspur, India, in the year 2010. It is a valuable method for the winning of coal resulting in 75% final recovery compared to high-capital-costs methods (i.e. longwall mining) in a given geomining condition. It is a type of retreat method, more commonly known as the Bord-and-Pillar method (BPM), or stoopand-room. There are only a few longwall projects in operation in India, and BPM is used almost exclusively for underground coal production. It is not a novel method; however, its reasonably recent application in the mechanised form represents the era of modernization of one of the world’s largest coal producers [1]. A critical consideration for successful implementation has been in the reduction of the significant risks inherent of retreat methods, for example drawing/winning of the naturally supporting pillars or the uncertainty of caving. These risks necessitate practical rational and are obviated via the design
* Ashok Kumar [email protected] 1
Council of Scientific and Industrial Research-Central Institute of Mining and Fuel Research (CSIR-CIMFR), Barwa Road, Dhanbad, Jharkhand 826001, India
2
Indian Institute of Technology (Indian School of Mines), Police Line Road, Hirapur, Dhanbad, Jharkhand 826004, India
of (i) roadways/galleries, (ii) extraction sequence(s), (iii) multiple seam interactions (iv) remnant pillar (snook) size, shape and placement, (v) goaf edge/breaker line support and (vi) induced caving [2]. Decision-making is aided with roof and pillar instrumentation, simulation software, past experiences, and industry-accepted pillar formulae [3]. However, the risk is never entirely avoided, and the designs mentioned above are far from rudimentary due to the rock mass conditions, which results in case-by-case analyses until such industry standards are finalised. This note s
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