Data shows that two years after the worst of the raw materials slump is over, investors are still not ready to pour in fresh funds despite a price rally.
On Thursday, Newcrest reported a 58% fall in half-year underlying profit, due to disruptions such as an earthquake hitting one of its key sites in 2017.
Freeport's export permit for Grasberg, the world's second-biggest copper mine, is due to expire on Friday, as is Amman's permit to ship ore concentrate from its Batu Hijau mine on the island of Sumbawa.
