Rock Mechanics Aspects of the Use of Underhand Cut-and-Fill Paste Sill Pillars: Case Studies

2011

Paul B Hughes, Rimas Pakalnis, Grant Corey, Peter Lawrence, Michael Hitch,

This paper summarizes current underhand paste backfill mining as applied to Goldcorp Inc’s Red Lake Mine, Newcrest Mining Ltd’s Kencana Mine and the Lanfranchi Nickel Mine. Red Lake utilises a 6 m wide undercut with a 2 MPa unconfined strength paste in order to selectively mine their high grade, high-stress orebody. Kencana’s orebody is located in a poor rock mass environment. An 8 m wide, 2 MPa unconfined strength paste sill allows a safe working condition for their high grade orebody. The Lanfranchi Nickel Mine utilises a cable supported, 2 MPa paste, 12 m wide undercut sill to optimize the mining of the weak rock mass ore. This paper details the rock mechanic hazards, ground support, paste practices and unique conditions for each mine. Further, an update of ongoing research at the University of British Columbia focusing on the optimization of safe mining in underhand cut and fill mining in high-stress/weak rock masses is presented.