CARTRIDGE SHELL AND CARTRIDGE FOR BLAST HOLES AND METHOD OF USE

摘要

Cartridge (10c) comprises body (12) defining a volume for holding energetic material. Body (12) has a first end (16) located adjacenta toe (48) of hole (46) formed in hard material (47), and a second end (18) directed towards collar (50) of hole (46). End (18) is tapered to form a point or wedge-like member. Stemming material (52) is placed in hole (46) to a level below free face (54) of hard material (47) and mechanically held in place by stemming b ar (56). When the energetic material is initiated, gas pressure forces cartridg e (10c) towards collar (50). As this occurs, the point acts to increase the radial compressive force on stemming material (52) in the annular region between end (18) and the adjacent portion of hole (46). This increases the sealing effect of stemming material (52) and maintains constant the volume i n hole (46) within which the gas operates.