ABSTRACT

The unique challenges of permafrost and constraints of pillar mining have necessitated many changes to the mining plan at the Polaris Mine since production first started in 1981. Frozen backfill, exposed to heights of 60 m to 90 m in pillar mining, has now been replaced by cemented rockfill. Ground conditions in pillar drifts have deteriorated significantly and require an intensive ground support program. Advancement of the pillar retreat front has caused massive caving of the hangingwall, adversely affecting pillar recoveries. Due to this caving, smaller stage sizes and quicker cycle times for mining are necessary. As the pillar retreat front progresses, ground conditions will further deteriorate and mining will become even more challenging. The Polaris Mine uses a flexible approach to pillar mining in order to overcome these concerns. The majority of remaining reserves must be mined using pillar recovery methods, therefore successful extraction of pillars is essential to meet production demands for the remaining mine life.