A study of UG2 pillar strength using a new pillar database

A recent experimental pillar extraction project at a UG2 bord-and-pillar mine presented unique opportunity to compile new database. Currently, the South African hard rock mines are designed using Hedley and Grant formula with modified K-value. This empirically derived was developed for uranium in Elliot Lake district of Canada. The use this design pillars Africa is questionable. Very few failures have nevertheless been observed its current calibrations various reef types possibly too conservative. database 66 pillars, which seven classified as failed, compiled by authors. enabled revised 'first-order' calibration K-value formula. estimated value K = 75 MPa. gives strength that more conservative than PlatMine work should be considered only preliminary small. Further also required determine whether exponents width height parameters appropriate pillars.