DRILLING AND BLASTING OPERATIONS AT OPEN PITS Russian patent published in 2014 - IPC F42D3/04 E21C41/26 

FIELD: mining.

SUBSTANCE: proposed method comprises drilling of parallel rows of wells, charging them with explosives and their short-delay blasting. This short-delay blasting of radially arranged charges in membrane layers is performed as follows. First row of wells is blasted, the third one from the bench edge. Then, 1 row of wells is blasted with 25 ms delay while 2 rows of wells are last blasted with 50 ms delay. To locate the membrane layers, rock mass is photographed to define the radius of curvature of bench mining block slope by relationship with due allowance for acoustic stiffness of rocks. Weighted average layer-by-layer quantity of systematic fractures per the width of mining block coverage W_c is defined. Weighted average spacing between two adjacent systematic fractures is defined. Degree of crushing and line of resistance at bench bottom are defined. Sums of rock bed depths and strength factor (by Protodyakonov scale) are calculated. Rock strain rate, clamp factor, explosive potential energy and blast efficiency are defined.

EFFECT: maximum development of rock mass, decreased consumption of explosives, higher yield.

4 dwg, 1 tbl