580 California St., Suite 400
San Francisco, CA, 94104
Figure 6 – uploaded by Norbert Baczynski
Figure 2 A favourable blasthole layout that might be considered to mine final pit slope faces is shown in Figure 2. This layout comprises several types of holes; i.e. pre-splitting holes (red), additional shallow holes (blue), buffer row holes (green) and normal production blastholes (brown). Spacing and blast-initiation delay between each blasthole type will depend on ground conditions. ‘igure 2. Example of a favourable blasthole pattern that might be used to mine final slope faces Notwithstanding the geotechnical merits of Figure 2, the main aim of blasting is to fragment waste rock anc ore to a size that improves the productivity of blasted rock digging, transportation and crushing. In additior to blasting shock energy (fragmentation), there is gas or bubble energy. The latter not only promote: fragmentation but, more importantly, creates heave and muck pile looseness to greatly assist dig rates This venting gas, if not effectively directed away from pit walls, can escape into fissures/joints in said benches exacerbating weaknesses and, in extreme cases, destroying bench crests due to excessive back-break.
Related Figures (19)
