Drilling and blasting techniques and costs for strip mines in Appalachia
On-site investigations of blasting techniques were conducted at twenty surface coal mining operations in the steep slopes of Appalachia. The mine sites represented a range of mountain mining methods and annual coal production levels; all sites used similar techniques and equipment for the removal of fragmented waste rock. Hole loading characteristics and constraints limiting blast designs were observed at each mine site. This report summarizes technical blasting data and geological conditions which require special design considerations. Three mine sites were selected for future research in fragmentation efficiency. Detailed economic data on drilling and blasting were gathered from the three research sites and are reported herein. A great deal of fragmentation difficulties stem from tough, unpredictable geology with specific bedding characteristics and local zones of defined structural weaknesses such as jointing and vertical seams. Exceptionally hard bedrock, existing as a caprock or as the basal layer above the coal seam, persists as the cause of oversize rock breakage or, in the latter case, damage to the coal unless special precautions are taken. Federal blasting regulations strictly control the amount of explosives used as well as throw of the fragmented rock. This requires that blasting modifications be employed. The nature and extent of blast modifications were observed to be related to terrain and demographic conditions around the mine site. Drilling and blasting costs reported for the three mine sites averaged $0.21 per cubic yard of material blasted. Drilling costs varied widely, as drilling time was indicative of geologies and often, drilling costs remained the greatest percentage of total blasting and drilling costs.
- Research Organization:
- Northwestern Univ., Evanston, IL (USA). Mineral Resources Engineering and Management Program
- DOE Contract Number:
- AC05-76OR00033
- OSTI ID:
- 6024856
- Report Number(s):
- DOE/OR/00033-T6; ON: DE83015147
- Country of Publication:
- United States
- Language:
- English
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