Mining Publication: Short-Delay Blasting in Underground Coal Mines
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Original creation date: January 1986
The Bureau of Mines has conducted research to determine whether the total elapsed delay time for blasting bituminous coal in underground mines could be safely expanded beyond the present 500-ms limitation without igniting a methane or methane-coal dust atmosphere. The results indicated that the increase of total delay from 500 to 1,000 ms had no detectable effect on safety relative to incendivity as long as permissible practices were observed in all other aspects. Research was also conducted to evaluate the safety of 18-in hole spacing for delay blasting in coal relative to misfires. For a variety of permissible explosives, misfires were observed for about 50 pct of the holes at 18-in spacing. Based on this observation, the Bureau has recommended that the new regulations prohibit hole spacings of less than 24 inches in underground coal mines. Misfires were also observed for 24-in spacing, but the number of misfires and test shots was too small to support any firm conclusions.
Authors: RJ Mainiero, HC Verakis
Information Circular - January 1986
NIOSHTIC2 Number: 10004993
Pittsburgh, PA: U.S. Department of the Interior, Bureau of Mines, IC 9064, 1986 Jan; :1-16
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- Frictional Ignitions in Underground Bituminous Coal Operations 1983-2005
- Guidelines for the Control and Monitoring of Methane Gas on Continuous Mining Operations
- MCP - Methane Control and Prediction - 2.0
- Methane Emission from U.S. Coal Mines in 1973, A Survey: A Supplement to IC 8558
- Methane Emission from U.S. Coal Mines in 1975, A Survey : A Supplement to Information Circulars 8558 and 8659
- Methane Emission from U.S. Coal Mines, A Survey
- Remote Methane Sensors
- Reservoir Rock Properties of Coal Measure Strata of the Lower Monongahela Group, Greene County (Southwestern Pennsylvania), from Methane Control and Production Perspectives
- Stochastic Modeling of Gob Gas Venthole Production Performances in Active and Completed Longwall Panels of Coal Mines
- Content source: National Institute for Occupational Safety and Health, Mining Program