Innovative technology of directional blasting using shaped charges

Abstract

Enhancement of mining performance is inseparable from blasting improvement. The quality of rock fragmentation by blasting for further processing and manufacture of final products governs the rate and efficiency of adva nce in the mining sector. The analysis of promising approaches to improvement of quality of rock fragmentation by blasting shows that the main way is to use modern physical fields to intensify detonati on processes, for instance, to utilize cumulative effect of blasting. The authors have designed a shaped charge with cumulative effect, which allows making the bench bottom lower and enables the blasting expenses to be reduced. With this charge design, an explosive charge is located immediately above the bench bottom, which increases the detonation wave impact on the bottom. The shaped charge generates a jet that creates a shock wave directed downward and sideways from the borehole. The stress waves directed upward from the shaped charge ensure additional fragmentation of overlying rocks. Direction of some explosive charge energy to the bottom of the borehole extends the time of the blast energy effect on enclosing rock mass and creates two stress waves. The proposed technology allows also decoupling of explosive charges with an inert gap. The lower charge element is made of an explosive conformable with the strength characteristics of rocks in the bench bottom, and the upper part of the charge is to conform with the blastability category of the bench rocks. Making a charge cavity at the bottom of the borehole allows having influence on the intensity of rock fragmentation by blasting. Efficient parameters of the charge cavity in the shaped charge design are determined.