Patent attributes
A method of blasting rock at an underground blast site in which boreholes (11a, b, c) are drilled in a rock mass 10 from a drive defining face 12, each borehole is loaded with at least one charge of explosive material (13a-c, 14a-c, 15a-c), at least one detonator is placed in operative association with each charge, and a sequence of at least two initiation events is conducted to blast the rock mass, in each of which only some of the charges are initiated, by sending firing signals to only the detonators associated with said charges and in which each initiation event is a discrete user-controlled initiation event. In one of the at least two initiation events a stranded portion of the rock mass such as a pillar is created that has already been drilled and charged, and the stranded portion of the rock mass is blasted in a subsequent one or more of the at least two initiation events without personnel accessing said stranded portion. First explosive charges (13a, b, c and 15a, b, c) may be blasted in the one initiation event, leaving a pillar of stranded ore with the preloaded borehole 11b extending through it. The detonators may be wireless.
