PolyMet Mining Corp., the company proposing a large open-pit copper mine in northern Minnesota, announced Thursday that it has appointed a new CEO who has extensive experience in mining.

Jon Cherry, a senior executive with mining giant Rio Tinto, will become president and CEO on July 16. He will be based in PolyMet's new corporate office in St. Paul, the company said.

The company is conducting a supplemental environmental study for the copper, nickel and precious metals mine near Hoyt Lakes, Minn., after environmental concerns were raised about the effects of sulfide releases, especially on wild rice.

PolyMet said Cherry is a recognized leader in mining environmental policy, has published extensively on mine environmental issues and has been a guest lecturer at Harvard University on sustainable development in mining and mine reclamation. Cherry holds an environmental engineering degree from Montana Tech of the University of Montana, the company said.

The current CEO, Joe Scipioni, will remain chief operating officer, and Douglas Newby will continue to serve as chief financial officer, the company said. Brad Moore will continue as executive vice president for environmental and governmental affairs.