Abstract
At the Mosaic K3 potash mine, the orebody (Esterhazy Member of the Prairie Evaporite Formation) has a regional dip to the south-west. Carnallite content in the ore has long been known to have a negative effect on the ground performance. At K3, mining of potash ore has been successfully completed at approximate depths of 3500’ below ground surface in sylvinitic ore (no carnallite), and 3300’ in carnallitic ore (carnallite content approximately 10%), with manageable differences in ground performance compared to the old K1 and K2 mines (depth approximately 3100’). New developments in the mine accessing carnallitic ore greater than 3500’ depth have been challenging to maintain. This presentation delivers a case study of the challenges encountered in the area.
The initial feasibility-level numerical modelling assessments are summarized, rock mechanics instrumentation data is presented and compared to the models, followed by a discussion of stress-relief alternatives considered.