Development of and production update for the Grasberg Block Cave mine – PT Freeport Indonesia

Authors: Brannon, C; Beard, D; Pascoe, N; Priatna, A Download Paper Open access courtesy of:

This paper is hosted with the kind permission of the Universidad de Chile, Eighth International Conference & Exhibition on Mass Mining, 2020.

DOI https://doi.org/10.36487/ACG_repo/2063_51

Cite As:
Brannon, C, Beard, D, Pascoe, N & Priatna, A 2020, 'Development of and production update for the Grasberg Block Cave mine – PT Freeport Indonesia', in R Castro, F Báez & K Suzuki (eds), MassMin 2020: Proceedings of the Eighth International Conference & Exhibition on Mass Mining, University of Chile, Santiago, pp. 747-760, https://doi.org/10.36487/ACG_repo/2063_51



Abstract:
This paper provides an update of the mine design, construction, caving progress and operations status of the Grasberg Block Cave (GBC) mine. Undercutting was initiated in September 2018 and drawbelling in December 2018. Undercutting is currently proceeding in three production blocks. Full production is expected in 2025, a 21-year time period between initial access development in 2004 to full production. Diluted ore reserves are about 959 million tonnes at a grade of 0.97% Cu and 0.73 g/t Au. The mine plan utilizes an El Teniente-style drawpoint layout on a 20 m x 30 m drawbell spacing, comprising some 2,400 drawpoints in a 720,000 m2 footprint. The drawpoint opening sequence comprises eight production blocks. Ore is transported via diesel-powered LHDs to a series of ore passes, then via loading chutes to a rail haulage system, which delivers the ore to a three-gyratory crusher complex. Crushed ore is transported to the mill stockpiles via dual inclined conveyors. Development and construction of the initial fixed facilities was completed in late 2018 and expansion of those facilities is ongoing to support production ramp up. Primary access for workers and materials is via the 6-km long AB adits. The service shaft for hoisting workers and materials from the AB adits’ level to the various operating levels was commissioned in 2016. The rail haulage central control system and initial haulage operating areas were commissioned in 2018. The first phase of the crusher/conveyor system was commissioned in mid-2018. Ventilation is provided through a series of large intake and exhaust drifts; four 5,000 kW main fans are operational, and a fifth fan will be commissioned in 2021. A 1,600 l/s pumping system will manage drainage from the mine. The initial stage of the pumping system is under construction and will be commissioned in 2020.

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