A stemming plug (60) for stemming a blast hole in a mine is disclosed. The plug has first and second wedge-shaped members (62, 62) manufactured from a suitable plastics material. The first wedge-shaped member (62) has a first sloping face received in sliding relationship with a matching face of the second wedge-shaped member (62) wherein, in use, when the first wedge- shaped member (62) is positioned nearest to an explosive material in the blast hole it has a larger surface area facing the explosive material than the second wedge-shaped member (62). In use, when a Shockwave from initiation of the explosive material in the blast hole encounters the first wedge-shaped member (62) it acts as a piston, sliding on the second wedge-shaped member (62) so that both wedge-shaped members exert diametrically opposed forces against the wall of the blast hole to lock the plug (60) in place. The two wedge-shaped members (62, 62) may be substantially identical, thus significantly simplifying the manufacturing process.

A stemming plug (60) for stemming a blast hole in a mine is disclosed. The plug has first and second wedge-shaped members (62, 62) manufactured from a suitable plastics material. The first wedge-shaped member (62) has a first sloping face received in sliding relationship with a matching face of the second wedge-shaped member (62) wherein, in use, when the first wedge- shaped member (62) is positioned nearest to an explosive material in the blast hole it has a larger surface area facing the explosive material than the second wedge-shaped member (62). In use, when a Shockwave from initiation of the explosive material in the blast hole encounters the first wedge-shaped member (62) it acts as a piston, sliding on the second wedge-shaped member (62) so that both wedge-shaped members exert diametrically opposed forces against the wall of the blast hole to lock the plug (60) in place. The two wedge-shaped members (62, 62) may be substantially identical, thus significantly simplifying the manufacturing process.

A plug (10) for blocking off mining exploration drill holes. The plug (10) comprises an elongate body (12) of solid impervious material, and an engineered surface (14) is provided on an external circumference of the elongate body (12). The engineered surface (14) comprises an annular anchoring groove (16) having a ramp (18) extending from a maximum diameter to a minimum diameter of the engineered surface (14) in a braking direction, in which it is intended to prevent movement of the plug (10) in the drill hole. The plug (10) also comprises an O-ring (20) received in the anchoring groove (16) and having a thickness whereby it protrudes slightly above the maximum diameter of the engineered surface (14) and engages with a wall (22) of the drill hole. In use, when the plug (10) is moved in the braking direction in the drill hole, the O-ring (20) rolls up the ramp (18) and wedges between the engineered surface (14) and the wall (22) of the drill hole to provide a braking action for the plug (10) against the wall (22) of the drill hole.

A plug (10) for blocking off mining exploration drill holes. The plug (10) comprises an elongate body (12) of solid impervious material, and an engineered surface (14) is provided on an external circumference of the elongate body (12). The engineered surface (14) comprises an annular anchoring groove (16) having a ramp (18) extending from a maximum diameter to a minimum diameter of the engineered surface (14) in a braking direction, in which it is intended to prevent movement of the plug (10) in the drill hole. The plug (10) also comprises an O-ring (20) received in the anchoring groove (16) and having a thickness whereby it protrudes slightly above the maximum diameter of the engineered surface (14) and engages with a wall (22) of the drill hole. In use, when the plug (10) is moved in the braking direction in the drill hole, the O-ring (20) rolls up the ramp (18) and wedges between the engineered surface (14) and the wall (22) of the drill hole to provide a braking action for the plug (10) against the wall (22) of the drill hole.

An above ground stemming device is described which includes a body configured, in use, to cover an open end of a blast hole loaded with explosives to surface or to within 300 mm of surface. The body has a void containing a stem of superabsorbent polymer gel therein and it is positioned in use to allow the stem of superabsorbent polymer gel to be in contact with the explosives in the blast hole. The body may include a base and an upper portion extending upwardly from the base. The void may extend through the body to an opening in the base. Alternatively, the void may be encased by the body. The body may be fabricated from a rigid material or from a flexible material capable of being inflated with a fluid.

An above ground stemming device is described which includes a body configured, in use, to cover an open end of a blast hole loaded with explosives to surface or to within 300 mm of surface. The body has a void containing a stem of superabsorbent polymer gel therein and it is positioned in use to allow the stem of superabsorbent polymer gel to be in contact with the explosives in the blast hole. The body may include a base and an upper portion extending upwardly from the base. The void may extend through the body to an opening in the base. Alternatively, the void may be encased by the body. The body may be fabricated from a rigid material or from a flexible material capable of being inflated with a fluid.

Provided is a piston-type explosive loading and blasting structure for a hard rock cable pit. The structure includes a first-step cut provided at a center of an excavation section and second-step cuts provided on a periphery of the first-step cut; and piston-type explosive loading structures are used for explosives in the first-step cut and the second-step cuts. According to the piston-type explosive loading structures in the present disclosure, due to plastic plugging of stemming and fixed elastic plugging of two disc steel plates, time of energy such as stress waves and explosive gas generated after the explosives explode acting on surrounding rocks is obviously prolonged, rock mass is fully broken, and loose blasting is formed without throwing.

A well tool device for forming a permanent barrier in a well includes a housing and an ignition device. A compartment is provided in the housing. A pyrotechnic mixture or heat generating mixture is provided within the compartment. The ignition device is adapted to heating at least a part of the pyrotechnic mixture or the heat generating mixture to its ignition temperature. If the pyrotechnic mixture is provided, the pyrotechnic mixture includes a first metal and at least a section of the housing is made of the first metal. If the heat generating mixture is provided, at least a section of the housing is made from a material being a constituent of the heat generating mixture.

A well tool device for forming a permanent barrier in a well includes a housing and an ignition device. A compartment is provided in the housing. A pyrotechnic mixture or heat generating mixture is provided within the compartment. The ignition device is adapted to heating at least a part of the pyrotechnic mixture or the heat generating mixture to its ignition temperature. If the pyrotechnic mixture is provided, the pyrotechnic mixture includes a first metal and at least a section of the housing is made of the first metal. If the heat generating mixture is provided, at least a section of the housing is made from a material being a constituent of the heat generating mixture.

Provided is an extensible spacer (14) for an inflatable blasthole plug (10) in the form of a collapsed bag (12). The spacer (14) includes a body (14.1) attached to the bag (12), and an associated leg formation (16) which may include leg segments (16.1, 16.2).