Patent ID: 8631744

Claim:
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 blast field having at least one free face at the level of the second body of material, the method comprising drilling blastholes in the blast field through the second body of material and, for at least some of the blastholes, at least into the first body of material, loading the blastholes with explosives so that for at least some of the blastholes a respective deck of explosives is provided in each of the first and second bodies of material and then firing the explosives in the blastholes in a single cycle of drilling, loading and blasting at least the first and second bodies of material, wherein the first body of material is subjected to a stand-up blast in said single cycle and said second body of material is subjected to a throw blast in said single cycle whereby at least 10% of the second body of material is thrown clear of the blast field beyond the position of said at least one free face, said throw blast in the second body of material being initiated before initiation of the stand-up blast in the first body of material, wherein for blastholes having at least a respective deck of explosives in the first and second bodies of material the explosives in the second body of material are initiated at least about 500ms before initiation of the explosives in the first body of material, and wherein the first body of material is buffered in the direction of throw defined by the throw blast of the second body of material.