Freeport-McMoRan plans to invest “aggressively” in copper mines in the southwest US after prices of the metal rose so high that many old operations are now profitable again, CEO Richard Adkerson said at the CERAWeek gathering in Houston, this week.

Copper’s rise to a record high “has made these old, low-grade mines economic” again, he said. Freeport is planning several mine expansions in the US but the government needs to speed up permit approvals if demand is to be met, he said.