Abstract:
In-pit waste rock dumping is often identified as an opportunity to short-haul as a pit phase nears completion. However, the ability to implement higher in-pit dumps can be difficult and may place a large burden on the technical services team. This paper presents key findings and lessons learned from the design, implementation, and performance of a high dump that exceeded 200 m at the New Gold Rainy River Mine, Ontario. The in-pit dump was advanced from the previously excavated bench slopes on the north wall.
The paper examines the pre-implementation work that contributed to initial stand-off distances, deployment strategy and de-coupling from the active mining to the south. The observed/monitored performance and ground control management strategy (i.e, shift restrictions, drone-based change detection) is presented along with lessons learned as the high dump faces were advanced south, including selection of analyses approaches that best represented the observed slope profiles.
Unique conditions that impacted the performance are also presented such as irregular crest profiles, historic overburden placement, over-steepened hang-ups, curved slope profile, rock roll-out shutes, weaker rock locally concentrated, and joining of a lower north-advancing dump.
Ultimately, an alternative bottom-up approach was adopted due to the burden of the strict ground control management and disruptions in slope advancement due to potentially hazardous conditions. The lessons learned are intended for others to consider when making the decision to form high in-pit dumps that appear to be easily persuadable due to economic upside but require a civil construction mindset to successfully implement safely.
Authors:
- Steve Boileau | Senior Rock Mechanics Engineer | SRK Canada
- Ed Saunders | Prinicipal Rock Mechanics Engineer | SRK Canada
- Cameron Drever | Mine Operations Superintendent | New Gold Rainy River Mine
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