Results 251 - 260 of 282

• Methane Emission from U.S. Coal Mines in 1975, A Survey : A Supplement to Information Circulars 8558 and 8659
  1/1/1977 - Information Circulars
  This Bureau of Mines report tabulates methane emissions from U.S. Bituminous coal mines with daily emission rates of at least 100,000 cfd according to states, counties, and coalbeds. Most of the methane emitted is from mines in the Appalachian States. T...
• Methane Emissions from Four Working Places in the Beckley Mine, Raleigh County, W. Va.
  1/1/1977 - Reports of Investigations
  The Beckley Mine is one of five new mines in a heretofore unmined portion of the Beckley coalbed. The remoteness of these new mines from prior mining and their greater overburden preclude applying methane emission experience obtained in the old mines. F...
• Degasification and Production of Natural Gas From an Air Shaft in the Pittsburgh Coalbed
  1/1/1976 - Reports of Investigations
  The Bureau of Mines conducted research to determine the effectiveness of long holes drilled in solid virgin coal in degasifying an area of the Pittsburgh coalbed showing that horizontal holes drilled into a virgin coalbed from the bottom of any shaft wi...
• Use of Surface Joint and Photolinear Data for Predicting Subsurface Coal Cleat Orientation
  1/1/1976 - Reports of Investigations
  Coalbeds exhibit a directional permeability, with the maximum permeability oriented parallel to the face cleat. Thus, the most efficient pattern of vertical degasification holes for a coalbed is dependent upon cleat orientation. Analysis of surface joi...
• Methane Emissions from an Advancing Coal Mine Section in the Pittsburgh Coalbed
  1/1/1976 - Reports of Investigations
  The methane emissions from an advancing coal mine section were continuously monitored for 120 days. During this time, the section advanced 2,000 feet into virgin Pittsburgh coalbed producing 54,565 tons of coal with a total methane emission of 91 millio...
• Technical Bulletin Pager Phones: Installation
  4/1/1975 - Contract reports
  The pager phones used in many underground coal mines are battery-operated, party-line telephones with provisions for loudspeaker paging. The system is two-wire, non-polarized, and is operated by self-contained batteries. A description of the many teleph...
• Rotary Drilling Holes in Coalbeds for Degasification
  1/1/1975 - Reports of Investigations
  Coal is a soft and brittle material. Drilling rates in the Pittsburgh coalbed using a drag bit exceed 3 ft/min at 2,500-pound thrust. However, maintaining the bit on a horizontal trajectory or parallel to bedding planes to attain lengths of 1,000 feet i...
• Two-Phase Flow in Coalbeds
  1/1/1975 - Reports of Investigations
  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.
• Hydraulic Stimulation Increases Degasification Rate of Coalbeds
  1/1/1975 - Reports of Investigations
  Coal degasification boreholes drilled from the surface have been successfully hydraulically stimulated to increase the flow of gas from the coal. This Bureau of Mines report describes the hydraulic stimulation procedure for a coalbed, the equipment requ...
• Research and Development Contract for Coal Mine Communication System: Volume 2 - Mine Visits
  11/1/1974 - Contract reports
  Eight coal mines were visited to determine their communications usage and requirements. Volume 2 details the eight mine visits, along with the conclusions reached following each visit and the final conclusions reached.