Depth of breakage per cycle is the most important factor in drilling-and-blasting performance. A square slot, as against a V-slot, allows increased depth of breakage and, accordingly, higher use factor of drill holes. A feature of square slots is compensatory (uncharged) holes drilled using special drill bits. Compensatory holes make it possible to enhance force of explosion in each hole, which reduces total number of holes to be drilled in a face as well as decreases quantity of explosives, primers and copper wire in hole loading. On the other hand, the compensatory hole drilling tools are far from being perfect.

The engineered and commercially tested new design drill bits for compensatory drilling by hand-held rock drills YT-28, jumbos and Boomer S1 D-DH drilling rig have demonstrated more than 2 times higher rate of compensatory drilling than series-production drill bits.


Drill bit–reamer, compensatory hole, shothole, drilling rate, reaming bits, rock hardness.

Issue number: 2
Year: 2018
UDK: 622.233.6.
DOI: 10.25018/0236-1493-2018-2-0-175-184
Authors: Karamanits F. I., Gromadskiy A. S., Kuzmenko D. I.

About authors: Karamanits F.I., Chairman of Board, PSJC «Krivorozhskiy Iron Ore Combine», 50029, Kryvyi Rih, Ukraine, Gromadskiy A.S. (1), Doctor of Technical Sciences, Professor, e-mail:, Kuzmenko D.I. (1), Assistant of Chair, e-mail:, 1) Kryvyi Rih National University, Kryvyi Rih., Ukraine.


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