Whiting, RK 2007, 'Stress Issues at Pajingo Mine', in Y Potvin (ed.), Proceedings of the Fourth International Seminar on Deep and High Stress Mining
, Australian Centre for Geomechanics, Perth, pp. 129-140.
Newmont Asia Pacific operates the Pajingo gold mine exploiting a series of narrow mineralised quartz veins
commonly referred to as the Vera-Nancy system. An underground operation since 1995, the site has recently
encountered stress related problems at mining depths of greater than 450 m below surface. Deterioration of
conditions at depth include intact rock failure, stress induced wedge failures, minor seismicity and
significant damage to reinforcement and hole closures with drilled stocks in advance of the mining front.
Specifically, the mine has shown stress conditions and rock mass damage that are difficult to control when
using a benching method which retreats to centrally located crosscuts below 450 m.
The design for the Jandam mining area was changed from a central retreat extraction method (using a single
crosscut access) to a more development intensive end access, centre out mining sequence, designed to
minimise stress induced damage. This allowed adoption of a key design modification in the form of an
inclined mining front with simultaneous production from multiple mining levels.
Successive extraction of individual panels with prescribed lead-lag distances allowed shedding of stress into
stope abutments making mining conditions manageable and maximising predictability and productivity.
This paper will discuss general stress related issues encountered on site and various strategies used to
manage the conditions. It will outline the background leading to the choice of mining methods and
operational variations adapted to the traditional sub level benching technique to control stress related
problems at Pajingo mine.
Ascott, B. (2005) Support requirements for Jandam Extraction Sequences. Newmont Pajingo Internal Memo.
Li, J. (2002) Report on Rock Property Testing for Pajingo. West Australian School of Mines, Curtin University.
Marisett, S. (2004) Draft Modelling review of Vera South Deeps Extraction. Newmont Pajingo Internal Memo.
Natural Resources Canada (2007) Narrow Vein Mining Research Project
Phillips, G. and Orr, L. (2007) Mineral Resource and Ore Reserve Report as of December 31, 2006. Pajingo Gold Mine
Villaescusa, E. (2002) Report on Acoustic Emission Testing of Jandam Core. West Australian School of Mines, Curtin
Stress Issues at Pajingo Mine R.K. Whiting
140 Deep Mining 07, Perth, Australia