Method and apparatus for blasting hard rock

A method for blasting hard rock comprising the steps of:

• (a) placing a prescribed volume of a fuel mixture in communication with a pair of electrodes proximate the rock formation, the fuel mixture having a sufficiently high metal content so as to form a plurality of fusible metal paths between the electrodes;
• (b) applying a moderately high electrical energy discharge to the volume of the fuel mixture;
• (c) fusing the plurality of metal paths to form a resistive arc channel between electrodes within the fuel mixture thereby producing a sufficiently high electrical resistance;
• and
• (d) dissipating a sufficient amount of heat from the resistive arc to the fuel mixture to initiate an exothermic reaction of the fuel mixture generating a rapidly expanding gas causing the fracturing and break up of the hard rock.

A blasting apparatus integrated with a rock drill, the blasting apparatus comprising:

• capacitive means for storing electrical energy;
• an insulating tube adapted to slidably traverse an elongated drill steel of the rock drill between a first position and a second position, the first position being a drilling position to allow drilling operations to proceed without interference from the insulating tube and the second position being a blasting position;
• and
• a metal sheath disposed on the outer surface of the insulating tube, the metal sheath switchably coupled to the capacitive means;
• wherein the drill steel is further connected to a ground potential, and the insulating tube, metal sheath and drill steel form a coaxial electrode assembly suitable for coupling the electrical energy from the capacitive means to a prescribed working fluid placed in communication with the metal sheath and drill steel.