Cushion Blasting and Breaking of Pebbly Alluvium Permafrost Rock Mass at Open Pit Coal Mines
Al. A. Galim’yanov, V. I. Mishnev
Institute of Mining, Far Eastern Branch, Russian Academy of Sciences, Khabarovsk, Russia
Keywords: Decoupled cushion charge, permafrost rocks, open pit coal mine, Quaternary deposits, blast design, blasting block volume
Abstract
The authors substantiate the use of the cushion blasting method and decoupled explosive charges to soften large-block (pebbly alluvium) permafrost rock mass at open pit coal mines in the cryolithic zone of Russia’ Far East. The key feature of the method is the decoupling of a borehole charge with separate initiation of the top and bottom portions at a delay not less than one day. This allows an artificial quasi-greenhouse effect owing to blocking of detonation products of the bottom charge. The introduction of the method at the Bureya Open Pit Mine in the Khabarovsk Krai ensured reduction of the powder factor more than by 1.5 times, increased underdrilling of up to 2 m to the design bench toe and enhanced level of safety due to a larger volume of mass blasts over 2 times.
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