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Results 231 - 240 of 259
1/1/1976 - Reports of InvestigationsMethane emission from two surface gob-degasification boreholes was measured by the Bureau of Mines. The investigation took place during mining of a 3,200-foot longwall panel in the Lower Kittanning coalbed in central Pennsylvania. The first hole was 500...
The methane content of virgin bituminous coalbed can now be measured accurately in the field with exploration core samples from vertical boreholes. The gas content of the coal per unit weight can be used either to design a mine ventilation system or to ...
This report describes a multipurpose borehole used for both degasification and the production of commercial-quality gas. The multipurpose borehole was drilled into a barrier pillar, and seven horizontal degasification holes and one pressure point hole w...
This report reviews experimental evidence indicating a relative permeability effect that causes the flow of methane to increase with time when a coalbed is degassed by boreholes.
1/10/1974 - Contract reportsField studies of ambient electromagnetic noise and electrical transmission properties of coal mine overburdens in Colorado, Illinois, Pennsylvania, and West Virginia were conducted. Field tests of the transmission of low-frequency (20 hz to 20,000 hz) s...
Methane concentration peaks were measured at coal mine working faces during entry development. The statistical distribution of peaks was found to be normal or log normal depending on how well the methane was being mixed into the ventilation airstream.
The Bureau of Mines has successfully used sulfur hexafluoride (SF6) as a tracer gas to measure mine air flows under conditions where conventional methods have failed. SF6 was employed experimentally to measure accurately recirculation of return into int...
Although it is generally believed that coal formation occurred at temperatures below 200 deg c, most experimental work on gas formation from coal has been performed at temperatures between 200 deg and 1,000 deg C. The objective of this Bureau of Mines e...
The Bureau of Mines found sulfur hexafluoride (SF6), released from a lecture bottle, to be an ideal gaseous tracer for studying mine ventilation systems. In a Pennsylvania limestone mine, this technique was useful in evaluating the effectiveness of auxi...
1/1/1974 - Information CircularsThis Bureau of Mines survey of methane emissions indicates that total daily emissions have declined from 227 mm ft3 in 1971 to 214.7 mm ft3 in 1973. The highest average daily emissions in million cubic feet per day are detailed by state.