Drill & Blast for Controlled Fragmentation

Designing the pattern around the crusher, not the drill

Fragmentation is a downstream result of an upstream decision. Before we set a pattern we ask what the primary crusher can accept and what the loading fleet is sized for, then work backwards to burden, spacing, hole diameter and bench height. A pattern that drills quickly but produces oversize has not saved money; it has moved the cost into secondary breaking and crusher downtime. Rock structure decides the rest — joint orientation, weathering and the position of any water-bearing zones all change how a blast performs, so patterns are reviewed against the face in front of them rather than repeated out of habit.

Initiation, timing and ground vibration

Timing does most of the work in a modern blast. The delay between holes and between rows governs how the rock moves, how well it breaks, and how much energy leaves the bench as ground vibration and airblast. Where a pit sits near communities, infrastructure or an existing highwall, the initiation sequence is designed to hold the charge weight per delay within the limits the site has to meet, and the result is monitored so there is a record rather than an assurance. Powder factor is tracked blast by blast against the fragmentation actually achieved, not against the fragmentation intended.

Handling, control and reporting

Explosives work is procedural work. Charging, stemming, tie-in and firing follow written method statements; exclusion zones, guarding and post-blast re-entry are controlled by a shot-firer with the authority to stop the job. Misfire procedures are rehearsed rather than filed. Every blast is notified, logged and reconciled — holes drilled against holes charged, explosive issued against explosive used — so the record stands up to an audit. We report fragmentation and vibration results alongside the production numbers, because the value of a blast only becomes visible in what the crushing circuit and the loading fleet can do with it afterwards.