Abstract:

Glencore’s Nickel Rim South Mine, located in Sudbury, Ontario, Canada, is a primary/secondary blasthole operation with ore zones lying between 1100 and 1700m below surface. One of the main benefits of the primary/secondary mining method in high stress ground is that up to 50% of the mining will take place in secondary stopes that should be in a yielded rock mass state. Every future secondary mining stope begins as a primary stope “abutment” pillar. As with many mines, the stress loading history and rock mass conditions can vary considerably in space and time. Safe mining practices cannot allow for an assumption that the planned secondary stopes are indeed yielded. An incorrect assumption can result in mining development and stoping taking place in high stress ground rather than the expected yielded rock mass conditions. This can result in higher levels of seismicity than expected and incorrect ground support recommendations in areas where workers could be exposed.

Seismic monitoring is the mines’ premier tool to track the actual rock mass response to mining. Yielded zones have a reasonably clear seismic signature/pattern over time that is visible in the collected data. The ability to accurately locate small magnitude seismic events can help define and delineate different stages of rock mass failure. The vast majority of the seismic data recorded by the microseismic monitoring system is below moment magnitude (M_w) 0.0. Examples are provided showing how small seismic events (M_w < -1.5) can help provide feedback from the rock mass deformation that allows the ground control engineer to gain a better understanding of how the rock mass is responding to mining processes.

Biography of the presenter: Brad Simser is the Principal Ground Control Engineer for Sudbury Integrated Nickel Operations, Glencore. During the past 30 years, he has worked as a ground control engineer with several operations. He currently oversees the ground control programs for the Fraser Mine Complex and Nickel Rim South Mine, is the lead for the future mines of Onaping Depth and Nickel Rim South Extension, and is a member of the Workplace Safety North Ground Control Committee. He has also worked in ground control in Canada for Craig and Onaping Mines, Noranda Technology Centre, and Brunswick Mine. In South Africa, he worked at President Steyn Mine. Brad has written numerous papers on the practical application of rock mechanics and principles in operating mines. Brad's knowledge, guidance, understanding, and recommendations have been helping people in underground jobs come home safely. He realizes that it is important for mining companies to investigate and document new methods and technologies for the next generation, with the hope that they will be able to further advance the field of rock mechanics. Brad is the recipient of the 2020 CIM Rock Mechanics Award.

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Mr. Tony Butler

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