Method of breaking a full face of rock for constructing shafts a

Details Method of breaking a full face of rock for constructing shafts a Method of breaking a full face of rock for constructing shafts a

1992-06-26

1993-08-03

Bagnell, David J.

Mining or in situ disintegration of hard material

Processes

Explosive

102312, 173184, E21C 712, F42D 304

Patent

active

052322688

ABSTRACT:
A method for breaking a longer round more efficiently in a full face of rock, to construct shafts or tunnels. In the method a relief hole having at least a 200 mm diameter and at least a 15 to 18 foot depth is drilled. Primary and secondary blast holes are drilled about the relief hole, approximately axially parallel to the relief hole. Most of the blast holes are drilled simultaneously with the relief hole. The relief hole is drilled by an in-the-hole (ITH) hammer drill, which if necessary is removed after drilling the relief hole, to allow blast holes to be drilled immediately adjacent the relief hole. The relief hole is drilled at least 10 to 15 percent deeper than the blast holes. Explosive charges are then inserted into the relief hole and most of the blast holes and are detonated in sequence.

REFERENCES:
patent: 2772632 (1956-12-01), Aitchison et al.
patent: 3957124 (1976-05-01), Desourdy
patent: 3967686 (1976-07-01), Fogelstrom
Blasters Handbook 15th Edition, DuPont Canada Inc., Chapters 16, 17, pp. 245-279, 1969.
Blasters Handbook, Canadian Industries Limited, Chapter VII pp. 215-257, 1968.
E/MJ Article "Open-pit concepts boost Inco productivity underground" pp. 101-104, May 1975.
Singh, S. P., "Empirical Guidelines for Drift Blasting", (1990) vol. 11 Mining Science and Technology, pp. 37-44.
Hagan, T. N., "Understanding the Burn Cut--A Key to Greater Advance Rates", pp. 2-8 (1979) Tunnelling 1979, Institution of Mining and Metallurgy.
Canadian Industries Limited, "Driving the Diversion Tunnel at Manic 3", Explosives Bulletin, 1972.

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