Authors: Talu, S; van As, A; Seloka, W; Henry, R


DOI https://doi.org/10.36487/ACG_rep/1002_28_Talu1

Cite As:
Talu, S, van As, A, Seloka, W & Henry, R 2010, 'Lift 2 North extension cave performance', in Y Potvin (ed.), Caving 2010: Proceedings of the Second International Symposium on Block and Sublevel Caving, Australian Centre for Geomechanics, Perth, pp. 407-421, https://doi.org/10.36487/ACG_rep/1002_28_Talu1

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Abstract:
Development of the Lift 2 North extension (L2NE) block cave commenced in September 2006, with the production ramp up in early 2008. The extension cave now produces in excess of 380,000 tonnes of ore a month with production planned to continue until the new Endeavour 48 (E48) cave has reached steady state production. Production of the L2NE cave will then resume once the E48 cave is exhausted. Caveability predictions during the feasibility study indicated that the highest risk to cave propagation was related to the higher rock mass strength on the eastern margin of the cave. Furthermore, the potential risk of early clay dilution entry from the depleted Endeavour 26 (E26) Lift 2 (L2) and Lift 1 (L1) caves was a major concern. The issue of poor caveability was addressed through the application of several techniques used to weaken the rock mass, namely, hydraulic fracture preconditioning, pre-split boundary weakening and preconditioning blasts along both the eastern and western margins of the cave footprint. In order to monitor and manage the cave propagation and clay dilution entry into the L2NE block cave, extensive cave monitoring systems were implemented, of which several open holes, over 300 m in length, proved the most valuable in detecting the cave back and muckpile positions. Northparkes was the first block cave mine to successfully trial and implement the Smart Marker technology to monitor cave flow.

References:
Bieniawski, Z.T. (1976) Rock mass classification in rock engineering, in Proceedings Symposium on Exploration for Rock Engineering Engineering, Z.T. Bieniawski (ed), A.A. Balkema, Rotterdam, pp. 97–106.
Dudley, J. (2007) Lift 2 Extension Draw Control Recommendations, internal report.
van As, A. and Jeffrey, R. (2000) Hydraulic fracturing as a Cave Inducement Technique at Northparkes Mines, in Proceedings MassMin 2000.




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