Methane gas emissions during longwall mining
- Bureau of Mines, Pittsburgh, PA (United States). Pittsburgh Research Center
- Island Creek Coal Co., Oakwood, VA (United States)
A detailed methane gas emission study was conducted during longwall mining in the Pocahontas No. 3 Coalbed, Buchanan County, VA. The purpose of the study was to measure gas emission characteristics from a 229 m (750 ft) wide longwall face during a sustained operating period and to estimate face emissions for a 305 m (1,000 ft) wide face. When the study began, approximately one-third of the panel had been mined. An extensive horizontal methane drainage program was conducted on this panel prior to the start of the study and removed approximately 4.63 Mm{sup 3} (163.3 MMft{sup 3}) of methane gas. The study involved continuous monitoring of face and bleeder gas emissions over a six-day period. Also, a production time study was conducted to provide records of the shearer location and equipment downtime periods. After an idle weekend period to establish baseline conditions, 82 complete passes of the shearer were studied. To permit data analysis, each pass was divided into three equal segments. Results of the study show that gas emission rates were lowest when a pass began (first segment). Gas emission rates then increased approximately 18% during the second segment, and remained constant during the third segment. Pass direction did not seem to affect mean methane emission rates. Methane emissions appeared to increased by 0.047 m {sup 3}/s (100 ft{sup 3}/min ) during a typical pass and decreased very rapidly during delays. Finally, the methane emission rate did not exhibit a steady increase, or staircase effect, as the number of continuous passes increased. The absence of a staircase escalation in the methane emission rate can be attributed to the horizontal methane drainage program. Given the existing mining conditions, it appears that face length could be extended to 305 m (1,000 ft) with a minimal increase in gas emissions.
- OSTI ID:
- 143760
- Report Number(s):
- CONF-930646--
- Country of Publication:
- United States
- Language:
- English
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