Prokopenko A. Substantiation of compositions and parameters of the explosive's mixtures external charges for the controlled destruction of oversize rock fragments

The technique for determining the required thermodynamic and explosion parameter is described. The technique for forming the resulting pressure at the rock-charge contact surface considering influence of the cylindrical shape charge's geometrical parameters and rock deformability is developed. The time of maintaining the level of the resulting pressure at the rock-charge contact surface is used as the criterion of efficiency crushing explosion external charge. Using the obtained crushability functions, pressure levels at which pressure is to be maintained while mudcapping in granite and limestone are calculated. Using the obtained methods of calculation of the resulting pressure on the contact surface and crushing efficiency criterion developed new recipes of explosive mixtures for use as external charges.The spread and reflection of shock waves process in the rock fragment when undermining external charge on its surface is considered. The analytical formulas for determining the size camouflet hollow, area of intense crushing and cracking zone, for determining the thickness cutoff layer in rock fragment are developed and the results of calculations are presented. For the first time the calculating formula for determining the mass of external charge required to perform fragmentation of oversize piece to its base without overgrinding and excess demand of explosives was analytically obtained. Developed algorithms, techniques and programs, as well as the empirical dependences, the analytical formulas, may be used to develop the new explosive mixtures for secondary blasting and to predict the results of external charges explosions.