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Results 231 - 240 of 255
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.
As one of its projects for degasification of major panels of coal prior to mining within them, the Bureau of Mines conducted methane emission studies during development of a set of three headings 1,800 feet in a major coal panel (2,700 by 3,500 feet) wh...
Geologic Factors Causing Roof Instability and Methane Emission Problems: The Lower Kittanning Coalbed, Cambria County, PaA geologic study of Mines 32 and 33 in Cambria County, Pennsylvania, was conducted as part of a methane control research program.
The applicability of the "direct method" for determining the methane content of virgin coalbeds was tested. Preliminary results indicate that the direct method, when applied to exploration cores, can be successfully used to estimate coalbed gas content ...
To determine if coals from mines which had no history of detectable gas emission contained adsorbed methane, samples of coal at the shaft bottom and at an active face were obtained and placed in sealed metal cylinders.