This comes a day after Freeport-McMoRan Inc said it would sell a majority stake in the world's second-biggest copper mine to the Indonesian state-owned miner via a series of complex deals worth $3.85 billion.

The Grasberg deal will be paid off quickly, helped by forecast returns from the mine, Inalum CEO Budi Gunadi Sadikin told Reuters on Friday.

"By our calculations it will be two years," he said, without providing any further details.

Freeport has said the deal will be positive for both sides, but noted the agreed value was far less than it could have gotten, highlighting the company's desire to end more than six years of wrangling that has weighed on its shares.

(Editing by Christian Schmollinger and Himani Sarkar)

By Fergus Jensen