Engineering & Mining Journal

AUG 2017

Engineering and Mining Journal - Whether the market is copper, gold, nickel, iron ore, lead/zinc, PGM, diamonds or other commodities, E&MJ takes the lead in projecting trends, following development and reporting on the most efficient operating pr

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BLASTING AUGUST 2017 • E&MJ 39 ergy. For this reason, burn cuts must be designed to avoid these problems either through dimensional design, timing or the use of special underground explosives. If a cut is dead-pressed, it will normally cause the round to freeze, resulting in minimal fragmentation and pull, plus an increase in ground vibration by up to five times. This dead-pressing is most common in the first cut where boreholes are very close together, due to poor design or borehole deviation. The dimensional design chang- es that can help prevent the consequences of dead-pressing are designing the round so that even if one hole in the first cut could not initiate, the round could still re- cover and perform (i.e., redundancy). An- other method is to increase the size of the relief holes, allowing expansion of the first cut and separation of the boreholes. Addi- tional methods are changing the timing of boreholes firing, and the use of emulsion with high crush strength microspheres, which are dead-press resistant, and using a strong booster with 1.1 emulsions to help initiate when pre-compressed. Conclusion The design choices for a burn round gen- erally concentrate on the relief and cut holes due to the large influence they have on the face advance, total cost and ef- fectiveness of the burn round. In unpub- lished research, the authors have seen large decreases in vibration from con- struction tunneling by changing only the cut and maintaining the same production hole design. Because of this, the design of the cut must be the first priority when designing a burn round. By using a stan- dardized pattern that has been studied and scaling it to meet appropriate volume requirements and drilling capabilities, an engineer or supervisor can quickly and easily implement or improve the burn round to their specific mine needs. References • Allen, M., & Worsey, P. (2014). Burn Cut Pull optimization through varying Relief Hole Depths. International So- ciety of Explosive Engineers. • Bullock, R. (1961). Fundamental Re- search on Burn-Cut Drift Rounds. The Explosive Engineer. • Konya, C. (1995). Blast Design. Mont- ville: Precision Blasting Services. • Konya, C. (2015). Rock Blasting and Overbreak Control. Montville: Preci- sion Blasting Services. • Konya, C., & Konya, A. (2016). Under- ground Blasting Seminar Manual. Montville: Academy of Blasting and Explosive Technology. • Langfors, U., & Kihlstrom, B. (1967). Rock Blastin. Sweden. Figure 3 — Optimal burn cut design. TAILINGS FLOTATION CELLS THICKENER UNDERFLOW CONCENTRATORS CENTRIFUGE AND CYCLONE FEED Series 5200 Control Pinch Valve Series D Slurry Knife Gate Valve Series DX Slurry Knife Gate Valve Series 75 Manual Pinch Valve Red Valve | 412.279.0044 The Best Choice for the Toughest Mining Applications. Since 1953, Red Valve Company has been the world's leading manufacturer of slurry valves for the mining industry. Built to last, Red Valve products are the industry's first choice for isolation and modulating valves througout a mining operation. Our global representative network stands ready to work with you.

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