Impact of In-Seam Dirt Bands on the Performance of Surface Miners in Coal Mines

Abstract

Surface miner was introduced for coal extraction at Lakhanpur open cast project of Mahanadi Coalfields Limited in 1999 for the first time and owing to its success and benefits it offered like elimination of drilling and blasting, smooth and stable high wall, selective mining for quality control and uniform output fragment size (-100mm) etc. it was adopted in many open cast coal mines and now has become a disruptive mass production technology for coal mining in India. In terms of coal resources in the country, Odisha stands first with 88.104 BT resources but the coal seams in Odisha are characterized by its high ash content and interlaced dirt bands (10 cm to 1.5 m) often termed as rejects. For maintaining coal quality, these dirt bands predominantly of sandstone and shale are also cut by surface miners and are segregated at the time of loading and transported to reject dumps or overburden dumps. These dirt bands have a significant impact on the performance of surface miners and must be taken into account during their selection. The authors, based on the intensive field study undertaken at different opencast coal mines in Odisha highlighted the impact of in-seam dirt bands in coal seams on the performance indicators of surface miners which are normalized production rate, diesel and pick consumption for cutting 1000te of material in this paper. Pick consumption was found to vary linearly with the quantum of abrasive material cut. Empirical relations for estimating monthly normalized production, diesel consumption, and pick consumption of surface miners operating in coal seams with intermittent dirt bands with a coefficient of determination (R2) of 0.74, 0.84, and 0.73 respectively were also developed. The developed relations were validated with the field data and the % error was found to be within +20%. This study helps the coal mining companies in the selection of suitable surface miners for achieving targeted production and also for planning inventory of picks and diesel during its operation.