Characterization of fragment size vis-à-vis delay timing in quarry blasts

This research investigates the effect of delay timing on fragmentation. The study reveals that delay timing plays crucial role in the fragmentation. The shorter delay timings were found to yield better fragmentation results in comparison to the longer delay timing in strong limestone benches. Additionally, under the existing field conditions, straight V-type firing pattern provided superior fragmentation results.

Present study reveals the influence of varying inter-row delay timings on size of the blasted rocks in limestone quarry. Digital imaging was implemented to characterize the fragment size distributions.Figure optionsDownload as PowerPoint slideHighlights
► Digital imaging technique with use of suitable software is capable of describing the fragment size and complete state of fragmentation within the blasted muck piles.
► Breakage by shattering effect necessitated shorter inter-row delay timing for efficient fragmentation. The shorter timing, in strong formations, seems to provide good opportunity of in-flight, inter-rock collisions before the final placement of the muck piles.
► The blasted mucks, from adjacent previous rounds, act as a buffer that restricts the broken rock movement in diagonal firing. This buffer must be excavated before firing the next round to ensure 2-clear free faces in the diagonal firing.
► Due to operational constraints, if it is not possible for the operators to clear the blasted muck buffer, then firing the blast rounds on V-type of firing pattern against a single free face, holds promise in providing good fragmentation results.