ABSTRACT
N.R.P. Baczynski, D. Bruggemann & W. Schiller Ok Tedi Mining Limited, Tabubil, Papua New Guinea
ABSTRACT: Ok Tedi is a major open-pit copper-gold mine in the southern highlands near the western border of Papua New Guinea with Indonesian Papua. The pit is near oval-shaped and has a narrow north-south trending drainage slot at its southern end, is 3000 m by 2000 m in area at crest perimeter and 750 m deep. By 2013, pit depth will be 900 m. About 150,000t to 200,000t of rock is mined daily; half this tonnage is ore. A 60 m deep mini open-pit was mined during 2009-2010 within the southern slot to recover ore outside the current pit mining limit. Slope instabilities have existed on both sides of the slot for several years. Structurally controlled, raveling-sliding and toppling failures are active on the east and west slopes, respectively. Cumulative ground displacements in excess of 25 m and 12 m have been monitored on the two slopes since 2005. Trends and key factors influencing displacements and the strategy used to safely mine the mini-pit through the landslides are described in this paper.
