Twenty-eight workers have died at Freeport-McMoRan Copper & Gold’s (FCX-N) Grasberg mining complex in Indonesia after the roof of an underground training facility collapsed on May 14. Ten others have been rescued.
The incident occurred about 500 metres from the entrance to the Big Gossan underground mine, the company said.
The Grasberg minerals district has three mines in operation: the Grasberg open pit, the Deep Ore Zone underground mine and the Big Gossan underground mine.
The Big Gossan mine is adjacent to the current mill site. It is a tabular, near-vertical orebody. Production there began in the fourth quarter of 2010.
Freeport says that Big Gossan uses a blasthole-stoping method with delayed paste backfill. Stopes of varying sizes are mined and the ore is dropped down passes to a truck-haulage level. Trucks are chute loaded and transport the ore to a jaw crusher.
The crushed ore is then hoisted vertically to a level where it is loaded onto a conveyor belt. The belt carries the ore to one of the main underground conveyors, where it is transferred and carried to the surface mill stockpile for processing.
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