September 1999Volume 51 Issue 9
Influence of coal properties and dust-control parameters on longwall respirable-dust levels
Mining Engineering, 1999, Vol. 51, No. 9, pp. 25-32
Organiscak, J.A.; Colinet, J.F.
ABSTRACT:Longwall mining is one of the most efficient underground coal-extraction methods. It now accounts for about 50% of the coal mined underground in the United States (Fiscor, 1997). Since the mid-1980s, improvements in mine layout and equipment design have significantly improved the efficiency of longwall mining (US Department of Energy, 1995). The increase in panel size, equipment power and reliability have allowed the hourly efficiency of longwall mine workers to increase from 1.4 t/h (1.5 stph) in 1983 to 3 t/h (3.3 stph) in 1993 (US Department of Energy, 1995). During this period, the average length and face width of longwall panels have increased by 21% and 39%, respectively. The average panel size in 1994 was 230-m (750-ft) wide and 2,135- m (7,000-ft) long (US Department of Energy, 1995). Power to the average longwall mining operation has nearly doubled, and shearer availability for cutting is, on average, above 95% (i.e., 5% downtime) (Organiscak et al., 1996). These changes in mine layout and equipment design have provided higher coal-seam extraction ratios at higher extraction rates.
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