Engineering & Mining Journal

JUL 2018

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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Page 56 of 75

SURFACE DRILLING JULY 2018 • E&MJ 55 A new, much more aggressive bit was shipped in just two months. In a tradi- tional iterative process, multiple bits would have been manufactured and run, resulting in small, incremental improve- ments over several seasons. Dramatically compressing the iterative process expe- dited the creation and use of a higher ROP bit. For an Australian iron ore mining ap- plication, RC Pro and AMP were used in concert to iterate multiple concepts until an ideal balance of toughness and ROP were achieved. In this case, the 12 ¼-in. RB63 bits achieved high ROP, but dulls commonly exhibited coring. A model was calibrated using actual drilling parameters and bit data. Model- ing analysis revealed higher loads on the nose insert rows, and the design software enabled the rapid creation of multiple cutting structure concepts to balance the loads. The first iteration was a traditional- ly conservative step toward a tougher insert shape to prevent breakage. This addressed the stated problem, and in the past might have concluded the de- sign changes. But simulations showed that while insert loading was improved, a ROP loss was predicted. Additional de- sign iterations were performed to refine the design and achieve the best com- bination of characteristics to optimize both ROP and durability. A Botswana diamond mine application using 9-7/8-in. bits was suffering from severe cone erosion leading to insert loss. The root cause was over-penetration of the inserts, leading to cone steel contact with the formation and cuttings. Design and simulation capabilities allowed engineers in the field to quick- ly conduct a design analysis without resorting to demanding CAD programs. Several simulations were performed remotely while engineering was on- site to correlate observed wear versus theoretical loading. The process devel- oped a new design AV60 bit with lon- ger inserts and more robust cone steel. AMP was used to analyze the cutting structure failure mode, and the data contributed to the engineering deci- sion to use a more aggressive cutting structure. Real-world drilling simulations in concert with rapid-cutting structure design is putting better performing bits in the field faster. Virtual drilling compresses bit development time by enabling multiple iterative analysis/de- sign cycles to be performed before the bit is manufactured and field-tested. As a result, bits can be easily and quickly optimized for specific rock and opera- tional characteristics, and immediate performance gains. Anthony Plana is engineering supervisor and Graeme McKenzie is North America and EAME regional director for Varel Min- ing and Industrial.

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