Yao, M, Sampson-Forsythe, A & Punkkinen, AR 2014, 'Examples of ground support practice in challenging ground conditions at Vale’s deep operations in Sudbury', in M Hudyma & Y Potvin (eds), Proceedings of the Seventh International Conference on Deep and High Stress Mining
, Australian Centre for Geomechanics, Perth, pp. 291-304, https://doi.org/10.36487/ACG_rep/1410_19_Yao
Vale has operated a number of underground mines in the Ontario division in Sudbury for over a century. During this time, numerous mining methods have been employed including cut-and-fill, drift-and-fill, post pillar cut-and-fill, modified sublevel caving, underhand cut-and-fill/drift and fill plus bulk mining methods such as vertical retreat mining (VRM)/slot-slash, uppers retreat and underhand bulk mining.
The division hosts a wide variety of orebodies of varying geometries, many of these at advanced stages of mining extraction. Consequently, the geomechanical challenges are substantial and include bothgravity-driven and rockburst-prone ground failure conditions that are further exacerbated by rock mass characteristics and ever-increasing mining depths. Typically the gravity-driven scenarios include the recovery of remnant pillars in old mined out areas, mining through consolidated backfill and recovery of post-failure sill pillars. Burst-prone conditions become a challenge when mining through stiff and brittle geological structures, upon recovery of highly stressed sill pillars in narrow vein ore bodies or when mining at depths in excess of 2,500 m from surface. Gravity driven and stress induced ground failures may occur simultaneously. Underhand cut-and-fill for sill pillar recovery in narrow vein ore bodies are also known to involve risk from both of these failure mechanisms.
The adaptation of ground support practices has accelerated over the last two decades leading to an overall improvement in both safety and production. Several cases are presented in this paper illustrating the successful implementation of ground support practices at two of Vale’s six deep mining operations in Sudbury. A particular focus of this paper will be on 153 Orebody of Coleman Mine, where highly stressed multi-sill pillars are being mined by utilising both overhand and underhand cut-and-fill mining method, and 400 and 461 orebodies of Creighton Deep, where mining takes place below 2,400 m from surface. The design and motivation behind the rationale for ground support design are investigated. The equipment, best mining practice and procedures are discussed, as well as products associated with each design.
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