Extraction design for multiple seams highwall mining in india - A case example
Highwall mining is a mechanized and productive method compared to conventional underground mining methods. It leads to added recovery of coal which is otherwise lost in the pit below the highwall. The major challenge envisaged is however the designing of web pillars in complex Indian geomining conditions, invariably comprising of multiple seams, some in close proximity, and multiple-pass extractions in thick seams. The method has been recently introduced in India in December 2010 with the operation of ADDCAR Continuous Highwall Mining Machine at Ramagundem Opencast Project-II (OCP-II) of Singareni Collieries Company Ltd. (SCCL). After successful extraction of two seams at OCP-II, the machine is now extracting at neighbouring Medapalli Opencast Project (MOCP) of SCCL. In this paper, hybrid empirical and numerical techniques employed to design web pillars in multiple seam scenario of MOCP Mine is discussed in detail. The paper explains the procedure adopted to design web pillars for the two blocks demarcated in MOCP considering maximum coal recovery and long-term stability. The paper also reviews the general prospects of Highwall Mining in India taking cues from the MOCP mine. Copyright 2013 ARMA, American Rock Mechanics Association.