FIRING PATTERNS AND ITS EFFECT ON MUCKPILE SHAPE PARAMETERS AND FRAGMENTATION IN QUARRY BLASTS

Abstract

Proper use of firing pattern vis-à-vis the blast requirements can provide optimal blast performance in terms of fragmentation, throw, wall control etc. This is largely attributed to the importance of firing burden in any blast round. By changing the firing patterns the firing burden, and, thereby the ratio of spacing to burden is also subject to change. Proper initiation timing is as important for fragmentation as the burden, spacing, sub drilling, stemming etc. Simultaneous initiation leads to the problems, such as, coarser fragmentation, blasting of a large number of holes at a given time which leads to the other problems. The present research study which was conducted in three limestone quarries where major problems such as of improper fragmentation, poor wall control, and poor heave characteristics of the muckpile were observed. Designed firing pattern was not able to provide the requisite fragmentation, and, even the throw. Modifications in firing pattern were implemented to obtain the required blast results.