Mining University of Kolsky Scientific Center of Russian Academy of Sciences:

V. A. Fokin, Leading Researcher, Doctor of Engineering Sciences, e-mail: fva666@goi.kolasc.net.ru

Kovdorsky Mining and Concentrating Plant:

M. B. Togunov, Leading Specialist of Drilling and Blasting Operations

S. V. Semkin, Mine Chief Engeneer

Yu. A. Shitov, Deputy Chief Engineer of Drillingand-Blasting Mine

The analysis of the technical literature has shown that existing design procedures of an interval of delay are constructed on the concept of formation of an additional surface of an exposure providing, according to the majority of the authors, favorable conditions for destruction of the next pedigree layer. Differently, the basic accent at a substantiation of this or that settlement formula becomes on maintenance of qualitative crushing of the blown up mountain weight. From the technological point of view such approach is justified and it is difficult to disagree with it. At the same time, considering great volumes of detonation and a regularity of manufacture of explosive works, the important factor for the deep open-cast mines characterized by long term of working out, maintenance of stability of ledges and separate sites of boards of an open-cast mine is that directly is connected with intensity of seismic action of mass explosions. Thereupon the technique of a substantiation of intervals of short delay detonations of well's charges is offered by manufacture of mass explosions in open-cast mines. In a basis the principle of decrease in probability of strengthening of the previous explosive impulse by the subsequent at the expense of partial or full of unloading of a pedigree file from action of the previous explosive impulse by maintenance of statistically prevailing time interval between chronologically consecutive explosive impulses, sufficient for dump of pressure of products of a previous detonation  of well's charges to the pressure which are not exceeding strength of breed on rupture is put. The most effective, statistically prevailing time interval is time of dump of pressure of products of a detonation of well's charge a charge to atmospheric.

1. Baranov E.G. Korotkozamedlennoe vzryvanie (Shortdelay blasting). Frunze, 1971, 147 p.