The world needs more mines to cope with rising demand for key energy-transition metals like copper, as mergers and acquisitions will not plug a looming supply gap, Rio Tinto Group Chairman Dominic Barton said.

Uranium Energy (NYSE:UEC) +2.3% pre-market Monday after saying it agreed to acquire Rio Tinto's (RIO) uranium production assets in Wyoming, including its fully-licensed Sweetwater plant and a portfolio of mining projects,