Patent ID: 6422147
Filing Date: 2002-07-23
Classification: F42D

Abstract:
A control system for controlling the initiation of detonation of a series of explosive charges (13) spaced apart from each other in boreholes (12) formed in a rock medium (10) to be blasted, said system being operative to apply controlled time difference in the time interval between successive detonations of at least one phase of the series of charges, and which includes at least three successive detonations, so as to reduce the probability of consecutive stimulation and amplification of ground vibration by reason of the detonation of the charges in the rock medium, said control system comprising:an electrically operated control device (14) operative to initiate energisation of detonators (15) associated one with each explosive charge (13) in a respective borehole (12); a sequential generator (16) connected to said control device (14) and which is programmed, or programmable, to cause operation of the control device so that the latter can initiate successive detonations of the series of explosive charges; and, electronic adjuster means (17) operative to initiate successive energisations of the detonators (15) of at least said one phase of the series of charges at selected different time intervals which have the effect of avoiding, or at least minimising, the generation of undesirable harmonic vibrations in the rock medium (10), wherein the electronic adjuster means (17) is connected to the control device (14) and is operative to apply predetermined adjustments to programmed time intervals set by the sequential generator (16).