Rock that is projected outside the blast clearance zone or outside the site limits must be classed as flyrock.

Factors affecting

Jointed and fissured rocks are more prone to fly rock than strong homogeneous rock. But massive rocks require more charge to achieve good fragmentation and hence cause more problems.

Explosives

Explosives having more Bubble energy throw out more fly rock than the ones where strain energy dominates.

Blast Design

Blasting parameters like burden, spacing, charge per hole, stemming, and delay interval play an important role in the throw of the blast. Burden should be selected to take into account the crater effect where in rocks get thrown out from cavities or weak zones in the bench. There should also be adequate delay between rows of holes to allow room for the rock to swell and displace previously blasted material.

The primary sources of flyrock are face bursting, rifling and cratering.