fire

In mining and quarrying, to fire means to trigger a carefully placed explosive charge, usually dynamite or ANFO (ammonium nitrate and fuel oil), that fractures rock or ore into manageable fragments. This is the central act of hard rock extraction: without the blast, the ore cannot be won. The charge is set in a drilled hole, tamped with inert material, then detonated electrically or by detonating cord to break the surrounding rock mass.

Firing operations are heavily regulated and site-specific. The size and spacing of holes, the amount and type of explosive, the timing sequence between multiple charges, and the blast pattern itself are all engineered for the geology at hand. A typical production blast in an open pit might involve dozens or hundreds of holes fired in millisecond-delayed sequence to direct the broken rock outward and downward in a controlled way, rather than all at once. This sequencing spreads the shock and improves fragmentation.

Misfire, where a hole fails to detonate on schedule or at all, is a critical safety issue. Premature detonation of adjacent holes, or sympathetic detonation due to shock in the rock, can wreck the blast pattern and endanger personnel. Geological surprises, such as unexpected water or void spaces, can also affect how a shot performs. Vibration and air blast from firing can damage nearby structures and must be measured and controlled.

The term is also used in small contexts: a worker might fire a single blast hole in a development heading, or a quarry operator might fire a small charge to loosen a stuck block. The principle is identical, but the scale and oversight differ sharply from a large production blast that requires specialist blast design and sign-off by a licensed blaster.