Patent ID: 9618310
Date: 2017-04-11
CPC Classifications: F42D

Claim:
1. In open cut mining for recoverable mineral, a method of blasting plural layers of material in a blast field including a first body of material comprising at least a first layer of material and a second body of material comprising at least a second layer of material over the first body of material, the method comprising: drilling rows of blastholes through the second body of material and, for at least a plurality of the blastholes, at least into the first body of material, loading the blastholes with explosives, in which at least a plurality of the blastholes that extend into the first body of material are loaded with a respective deck of explosives in each of the first and second bodies of material, and firing the explosives in the first and second bodies of material in a single cycle of drilling, loading and blasting at least the first and second bodies of material and configuring delay times of detonators of the explosives in the first and second bodies of material in a manner to subject the second body of material to a blast of different design compared to the blast of the first body of material and to produce a different blast outcome in the second body of material compared to that in the first body of material, wherein configuring delay times of the detonators of the explosives in the first and second bodies of material in each blasthole to produce the blast of different design comprises providing in said at least a plurality of the blastholes having a respective deck of explosives in each of the first and second bodies of material at least one of 1), between adjacent rows, different inter-row blasthole delay times of the detonators for the explosives in the second body of material relative to the detonators for the explosives in the first body of material, wherein the different inter-row blasthole delay times comprise, for at least two blastholes in adjacent rows having a respective deck of explosive in each of the first and second bodies of material, a first delay time between initiation of a deck of explosive in the second body of material in one blasthole in one row and initiation of a deck of explosive in the second body of material in an adjacent blasthole in any adjacent row which is different from a second delay time between initiation of a deck of explosive in the first body of material in the one blasthole and initiation of a deck of explosive in the first body of material in the adjacent blasthole or 2), in any one row, different inter-hole blasthole delay times of the detonators for the explosives in the second body of material relative to the detonators for the explosives in the first body of material, wherein the different inter-hole blasthole delay times comprise, for at least two blastholes in the same row having a respective deck of explosive in each of the first and second bodies of material, a first delay time between initiation of a deck of explosive in the second body of material in one blasthole in the row and initiation of a deck of explosive in the second body of material in another blasthole in the same row which is different from a second delay time between initiation of a deck of explosive in the first body of material in the one blasthole in the row and initiation of a deck of explosive in the first body of material in the other blasthole in the same row.