METHOD FOR BLASTING OF ROCKS IN OPEN PITS Russian patent published in 2010 - IPC F42D3/04 F42D1/08 

FIELD: blasting.

SUBSTANCE: invention is related to the field of blasting in mining and may be used in blasting of rocks by borehole charges of explosives in open pits. Method for blasting provides for drilling of blastholes, formation of gas cavity in bottom part of one or several blastholes, arrangement of explosive charge in each blasthole over air cavity with intermediate detonator and facilities for initiation of the latter and execution of explosion. Drilling of blastholes is carried out until elevation of underlying ledge foot, and prior to formation of gas cavity, reflector of shock waves is installed at the bottom of blasthole. As reflector of shock waves, it is possible to use loose substances with various density, value of which is in direct proportion to rock pressure. Intermediate detonator is installed over gas cavity in active part of explosive charge at the distance from lower end of specified charge within the limits of 1-1.5 of gas cavity height. Gas cavity may be formed with the help of elastic reservoirs filled with compressed air or other gas with maximum nondestructive pressure for these reservoirs or filled with granulated cellular polystyrene.

EFFECT: invention makes it possible to reduce costs for execution of blast-hole drilling works and to reduce scope of drilling works.

5 cl, 1 dwg