Resembling a block in shape.

A cap-sensitive explosive with a high VOD used generally in small quantities to rapidly attain and maintain a high rate of detonation through the main charge.
Generally refers to a cast booster containing Pentolite.

Electric detonator for firing from the bottom of a perforating gun.

May be fluid sensitive of fluid resistive

A pattern of holes adopted for blasting to a new level below an existing floor or below existing surface mining.

The ability of an explosive to break or shatter rock by shock or impact as distinct from gas pressure.
The shattering effect of the energy released in an explosion.

The explosive strength value of a unit volume of an explosive material expressed against a standard reference such as ANFO.

A blast hole which has been enlarged (chambered) to accommodate extra explosive over a portion of its length (usually at the bottom) by exploding a small charge.

The burden is the distance between a blasthole which is to be fired and the nearest void or free space.

Note that two burdens are defined, the drilled burden as shown in the diagram and the dynamic burden which is the true burden at the instant the hole fires.

The dynamic burden is influenced by both the drilled burden and the delay timing.

The burn, or parallel hole, cut relies on larger diameter uncharged holes to provide the initial void to fire into.

These ‘reamer’ holes have limited volume so the burn cut starts with firing holes on very small burdens to ‘nibble’ the rock out until sufficient void and a second free face is created.

The initial holes pulverise the small amount of rock in the cut and then use the high pressure gases to clear the void. Unlike bench or stripping blasting the broken rock must undergo a change of direction and be squirted out the narrow cut area. This process takes some time and is the reason for the use of ‘Long Period’ (LP) delays.

As a second free face and void is developed blasting transitions to stripping geometries with maximum burdens and sufficient relief.

The burn cut requires a high degree of drilling accuracy to be reliable and there is a trend toward machine guidance systems on drilling machines to optimise drill accuracy.

Whilst these have been shown to be very effective in maximising blast effectiveness, and have been widely adopted into construction tunnelling, they have had limited acceptance in mine development due to operator resistance and maintenance issues.

The distance that the initiation system has functioned in front of the blast firing.