METHOD FOR CONTOUR BLASTING Russian patent published in 1994 - IPC

FIELD: blasting works. SUBSTANCE: rows of contour and precontour boreholes 2 and 3 respectively are drilled in destructible mass. The contour and precontour boreholes are staggered in plane in the vertexes of assumed flat broken line with angles equal to 80-100°. The contour boreholes are charged with reduced charging coefficient, and the precontour ones - with rip charges. All boreholes are exploded simultaneously. EFFECT: improved behind-the-contour mass preservation. 1 dwg