Fragmentation control is perhaps the most critical aspect of quarrying
operations, potentially impacting on the costs of all down stream
processes, and sometimes even on the economic viability of an operation.
The focal points of studies to control fragmentation are generally the
pattern of blastholes, the accuracy of drilling, and the most appropriate
powder factor. Recent studies suggest that the performance, and consistency of
performance, of explosive detonation in the blastholes may also be a
significant factor impacting on blast performance in hard rock quarries. This paper presents the results of studies of bulk emulsion and watergel
explosive performance, using blasthole velocity of detonation
measurements, and its impact on fragmentation. Field studies show a
strong correlation between blasthole VoD and blast fragmentation.
Another aspect of explosive performance impacting on ease of excavation
of blasted rock is muckpile displacement, from which estimates of
effective heave energy have been made for different bulk slurry (emulsion
and watergel) products.