METHOD OF DRILLING AND BLASTING OPERATIONS ON LIMIT CONTOUR OF FLANKS OF PITS AND GROOVES Russian patent published in 1995 - IPC

FIELD: mining industry. SUBSTANCE: rows of contour and ripping boreholes are drilled over contour of slope, bench or groove in zone adjoining zone close to contour. Drilling of last row of ripping boreholes in zone bordering on one close to contour is performed at some distance from contour boreholes determined by dependence R₁≅ R≅ R₂,, where R is distance from last row of ripping boreholes located in zone bordering on one close to contour to contour boreholes, m; R₁ is minimal distance equal to 30-40 diameters of borehole, m; R₂ is maximum distance equal to half zone of cracking over surface, m. Contour and ripping boreholes in zone bordering on one close to contour are loaded with explosive charges. After blast of contour charges first of all ripping boreholes in zone bordering on one close to contour are blasted. After this blasted rock mass is removed, ripping boreholes are drilled in zone close to contour, are charged and blasted. EFFECT: reduced expenditures and provision for keeping safe rock mass beyond contour by shielding of seismoblasting waves thanks to additional growth and opening of cracks in plane of blasted contour charges. 6 dwg