Watson B.P., Pretorius W., Mpunzi P., Du Plooy M., Matthysen K., Kuijpers J.S.
Design and positive financial impact of crush pillars on mechanized deep-level mining at South Deep Gold Mine
Journal of the Southern African Institute of Mining and Metallurgy
Gold Fields Ltd, South Africa; SRK Consulting (South Africa) (Pty) Ltd, South Africa; Centre for Mining Innovation CSIR, South Africa
Watson, B.P., Gold Fields Ltd, South Africa; Pretorius, W., Gold Fields Ltd, South Africa; Mpunzi, P., SRK Consulting (South Africa) (Pty) Ltd, South Africa; Du Plooy, M., Gold Fields Ltd, South Africa; Matthysen, K., Gold Fields Ltd, South Africa; Kuijpers, J.S., Centre for Mining Innovation CSIR, South Africa
Crush pillars have been incorporated into a mechanized, low-profile trackless system at South Deep Gold Msine. These pillars had to be designed to fail near the face and to ensure that pillar failure is contained within the pillar, to avoid bursting and the risk of high loads being generated during a seismic event, respectively. PoweRite backfill bags were recommended to maintain the integrity of the pillars; except in the main access drives, where the sidewalls were to be supported on 5.6 mm diameter weld mesh and yielding anchors. The results of a trial site investigation exceeded expectations, showing a residual pillar strength of about 37 MPa for a newly formed pillar and 8 MPa for a pillar subjected to seismicity and a closure of more than 300 mm. The introduction of these pillars has improved the rock mass conditions because of the active nature of the support, compared to the previous passive backfill method. Importantly, the pillars have increased mining efficiencies and improved face availability. A potential cost saving to the mine of R140.9 million could be realized over a period of 10 years. © The Southern African Institute of Mining and Metallurgy, 2014.
Backfill; Crush pillars; De-stress mining
Economic geology; Gold; Gold mines; Backfill; Crush pillars; Deep gold mines; Deep-level mining; Financial impacts; Pillar failures; Residual pillars; Site investigations; Room and pillar mining