Spherical stemming plug and method of use

Abstract

A method of stemming a borehole (6) includes the steps of placing a first layer (16) of stemming in the borehole, placing a spherical body (20) in the borehole on top of the layer (16), the body being relatively incompressible and a diameter slightly smaller than the diameter of the borehole, and placing a second layer (18) of stemming in the borehole over the body. The stemming (16, 18) may be placed in the borehole either in direct contact with an explosive (8), or spaced from it by a gas bag (24) or the like form a deck (22). In accordance with an alternate application, the stemming layers (16, 18) may be placed in the borehole prior to placement of an explosive material such that it serves as backfill. Preferably, the stemming includes crushed rock and drill cuttings such as those produced during formation of the borehole. However, other available materials may also be used such as gravel. The plug body is formed of a relatively incompressible material such as a ultra-high molecular weight polyethylene material, filled plastic shell, metal, ceramic or the like.

Dependencies are inferred from the claim text.