Engineering & Mining Journal

AUG 2013

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PRODUCTION BLASTING stations. As is well known, low vibration amplitudes can be caused by a variety of causes such as varying geology (Fleetwood and Villaescusa, 2011), poor loading practice, hole deviation resulting in dislodgement of or damage to explosive charges in adjacent blast holes, or the quality of the explosive products itself. However, these apparent blast malfunctions cannot be attributed to the above causes in the great majority of the production blasts in question, especially since the blasts were monitored at multiple accelerometer stations. Although none of the above factors can be ruled out in some individual cases, the widespread malfunctions exemplified in this study point to a more systemic cause for these apparent failures such as lithologic factors. The effect of the latter is evident from wide-scale blast hole deformation due to high ambient stresses that are characteristic in some of the stopes at this deep mine, and is part of the continuing investigation. The study also aims to provide not only superior blast diagnostics but also improved blast designs to counter these deficiencies. Acknowledgement The authors are grateful for the financial assistance provided by the National www.e-mj.com Science and Engineering Research Council of Canada and Vale Canada during the course of this research. In addition, the extensive assistance provided by Vale for field monitoring of vibrations in one of their underground mines is also gratefully acknowledged. Mohanty and Zwaan are professors at the Lassonde Institute of Mining at the University of Toronto, and Malek is a rock mechanics engineer working with Vale's Copper Cliff mine in Ontario, Canada. This article was adapted from a paper Mohanty presented at the 2013 International Society of Explosives Engineers conference, which took place during January in Nashville. The next ISEE conference will be held in Denver, Colorado, February 9-12, 2014 www.isee.org). References Farnfield, R., 1996,"So you think you are monitoring peak particle velocity"; Proc. 12th Symp. on Ann. Symp. on Explosives and Blasting Res.; Int. Soc. of Explosives Engrs.; p. 13-20. Fleetwood, K.G., Villaescusa,E., Li, J. and Varden, R.; 2009,"Comparison of traditional near-field vibration prediction models with three-dimensional vibration scaling and blast wave energy"; Proc. 9th Int. Symp. on Rock Fragmentation by Blasting (FRAGBLAST 9), Sanchidrian, J.A.;ed.; CRC Press, p. 579-588. Fleetwood, K.G. and Villaescusa, 2011, "Measured results of the influence of of a large- scale fault on blasting vibrations in sub-level open stoping"; Proc. 37th Ann. Conf. on Explosives and Blasting Tech.; Int. Soc. Explosives Engrs., ISEE, p. 1-13. Mohanty, B. and Yang, R.,1997, "Blasting vibrations and explosives performance"; Proc. 13th Ann. Symp. on Explosives and Blasting Res., Int. Soc. Explosives Engrs.,ISEE, p.15-28. Mohanty, B.; 2009, "Intra-hole and inter-hole effects in typical blast designs and their implications on explosives energy release and detonator delay time—A critical review"; Proc. 9th Int. Symp. on Rock Fragmentation by Blasting (FRAGBLAST 9); Sanchidrian, J.A; ed., CRC Press, p.23-31. Segarra, P, Sanchidrian, J.A., Lopez, J.M.; Querol, E. and Guiterrez, J., 2009, "Assessment of the error of blast vibration measurements"; Proc. 9th Int. Symp. on Rock Fragmentation by Blasting (FRAGBLAST 9); Sanchidrian, J.A; ed., CRC Press, p.551-560. AUGUST 2013 • E&MJ; 57

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