Coal Age

MAR 2019

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28 www.coalage.com March 2019 blasting continued Rock Mass Powder factor has never really been defined for the rock mass, which includes the depositional environ- ment and the structure of the rock. These properties massively affect the way a blast will behave and, as such, the blast design needs to ac- count for these properties to ensure any blast will achieve optimal per- formance regardless of the rock's structural geology. The first consideration is the case of the rock's depositional en- vironment, which is the method in which it was deposited. For igne- ous and metamorphic rocks, this is typically in a massive form, but of- tentimes for sedimentary rock nu- merous distinct bedding planes are present. These bedding planes can be of various strength and can ex- ist in three orientations, which are dipping into the cut, dipping away from the cut, and other (typically indicates either no strong bedding present or blasting along the strike). With a blast where the rock is dipping into the cut, the burden can oftentimes be expanded by 18% compared to blasting along the strike. When the bedding is dipping away from the cut, the burden typi- cally has to be reduced by about 5% to have the same breakage as blast- ing along the strike. To understand the effects this has on the blast, as- sume that for this case the blaster decides to use a powder factor of 1 (0.59). One side of the mine is blast- ing with the bedding dipping into the cut and the other side is blasting with the bedding dipping away from the cut. The difference in spacing in this situation is nearly 30%, which is extremely significant. The spacing comparison for the situation using powder factor de- sign or the Independent Variable Konya Design is shown in Table 1. The Independent Variable Konya Design is a design approach that uses the actual mechanics of the blast to determine design variables to optimize blast and has been stud- ied by several authors over the last few decades and proven to be the Table 1—Changes in Powder Factor based on the depositional environment. Powder Factor Design Independent Variable Konya Design Bedding Dipping Into Cut 0 92% 116% Bedding Dipping Away From Cut 116% 0 96% Other 108% 100% Adding digital intelligence Dtect By adding Dtect to torque limiting couplings, you get real-time monitoring of the driveline per for- mance, productivity and status. The system is designed to predict potential problems, protect the driveline and prevent costly downtime. Visit us at Bauma in Munich, Germany from April 8 – 14, 2019 Hall C2, booth #239 voith.com/dtect

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