Keywords and Phrases
Delay Timing; Rock Blasting
"Optimized rock fragmentation is essential for minimizing downstream costs to mining operations. Photographic fragmentation analysis, vibration monitoring, and high-speed video all provide measurements of blast effectiveness and supply data that allows operations to modify blasts to achieve downstream goals.
This study evaluates the effects of short hole-to-hole delay times on rock fragmentation. Photographic fragmentation analysis and various delay times were used on the same bench blast, the effects of timing on fragmentation were determined. This analysis provides a representative understanding of timing effects on fragmentation in the field, different from previous blast models which either negate the effects of timing or geology. Four test blasts were conducted at a granite quarry in Talbotton, GA. For each test blast, the bench was divided into three timing zones. This allowed for multiple delay times to be evaluated in each shot and it provided visual comparison of the variable face movement and throw. Hole-to-hole delay times included 0 ms, 1 ms, 4 ms, 10ms, 16 ms, and 25 ms across the various zones. The 16 ms and 25 ms times were the baseline times against which the short delay results were evaluated. The 0 ms and 1 ms times included stress wave collision regions, and the 10 ms time was based on the speed of sound in the rock and burden distance. Each blast was monitored using high-speed video and seismographs. Dyno Consult provided additional seismograph and video monitoring, along with bore track and 3D laser profile data. Multiple photographs were taken of each of the zones for WipFrag analysis. Based on the fragmentation analysis the 25 ms and 10 ms delay times resulted in the smallest rock fragmentation, while the 1 ms delay gave the coarsest fragmentation"--Abstract, page iii.
Johnson, Catherine E.
Worsey, Paul Nicholas
Mining and Nuclear Engineering
M.S. in Explosives Engineering
Missouri University of Science and Technology
ix, 145 pages
© 2015 Margaret Ruth Hettinger, All rights reserved.
Thesis - Open Access
Library of Congress Subject Headings
Electric detonators -- Testing
Rocks -- Cleavage
Blast effect -- Measurement
Electronic OCLC #
Hettinger, Margaret Ruth, "The effects of short delay times on rock fragmentation in bench blasts" (2015). Masters Theses. 7466.