Application of electro-discharge blasting technology for destruction of oversized rocks and rock massive splitting off

The investigation of possibilities of the plasma blasting technology is considered. The method is based on the initiation of a pulsed electric discharge inside the solid dielectric material. The expanding plasma channel generates a shock wave which in the vicinity of the channel (1-2 mm) transforms into the elastic wave with an expressed region of tensile tangential stresses that in turn stimulate the radial crack nucleation. The efficiency of solid destruction at shock-wave action strongly depends on the pulse parameters. The high-current pulse must fulfil the requirements to such parameters: the high-rate of rising edge (0.1-10 μs) and pulse duration (≥ 200-300 μs). The experimental results have shown that the optimal ratio of the borehole depth is 0.6-0.7 from the oversize rock height. For splitting rock massive off the borehole depth should be at least 2 and not more than 5 electro-explosive cartridge lengths and distance between the boreholes should be equal to 1-2 of the boreholes depths. On the basis of the experimental results the recommendations for the electro-discharge destruction and splitting off oversized rocks are presented.