Blast Hole

A borehole drilled into rock in a defined pattern for loading with explosives prior to detonation. Blast holes are characterised by their diameter, depth, inclination, spacing, and burden, which are determined by the blast design. In open pit mining, production blast holes typically range from 100 to 400 mm in diameter and are drilled by rotary or down-the-hole (DTH) hammer drills. Blast hole dimensions and loading determine the degree of fragmentation achieved and the efficiency of subsequent loading and hauling operations.