Borehole Delay
Borehole Delay
the explosion at various times of separate parts of a space charge in a blasthole, with a time interval of thousandths of a second. The delay ensures the influence of the explosion of part of the charge on rock that is in a state of tension after the detonation of previous parts of the charge, increasing the portion of the explosion’s energy that is used for crushing. Multicharge short-delay explosions create the best conditions for interference of compression waves at all points of the part of the mass being broken out and thus ensures even crushing of the rock, which is particularly important for its subsequent removal and processing. Delay inside the borehole is achieved by the placement in the hole of several delay electric detonators or several threads of demolition cord with pyrotechnic relays for independent detonation of the part of the charge. These charges are used for explosive breaking-out of tough rock in the borehole in quarries.