A recoverable plug for the blasting hole of a mine. A steel ball is enclosed within one hollowed-out portion of the plug, and sealed therein, so that the plug may be magnetically recovered after the blasting has been completed; or later, when the mined material is treated with a fluid such as water. The hollowed-out portion is further charged with compressed air, or similar fluid, to assist in absorbing the shock when the blast occurs, with the hollowed-out-portion also making the plug bouyant when it passes through a washing or similar liquid. Suitable expansion means is provided to "seat" the plug in a blasting hole.
展开▼
