STEMMING FOR BIG WELLS Russian patent published in 1998 - IPC

FIELD: drilling and blasting operations, in particular, locking of charge cavity (of well), applicable in mining industry at breaking of rock in quarries and opencast collieries. SUBSTANCE: stemming is featured by presence of high-pressure polyethylene as a plasticizer in material used for its production, and the filled, in addition to the high- density component (SiO₂), contains salt of alkaline earth metal functioning both as an ignition inhibitor and as a catalyst for reduction of intermediate product of oxidation into end products, with correlation of high-pressure polyethylene-filler-salt=3:4:3; the inner section of stemming has the shape of an extended hemisphere matched with a truncated cone, with the length of the spherical and tapered sections correlating as 1:1, and total length of stemming L₃= 5R₃, where R₃ - stemming radius commensurable with the radius of charge cavity; for alignment of stemming in well provision is made for pushing- apart blades. EFFECT: reduced manufacturing cost of stemming, simplified procedure of charging, reduced specific consumption of explosive of the same type, reduced ejection of poisonous gases and small fractions of dust into atmosphere at a blast. 3 cl, 1 dwg