The Minnesota DNR says an environmental study of a proposed expansion at the Keetac taconite mine near Keewatin is adequate -- a ruling that paves the way for the company to apply for permits.
The expansion would enlarge the mine pit and re-start an old production line, to increase pellet production from six-and-a-half-milliontons to nine-and-a-half-million tons a year.
U.S. Steel says it will invest more than 300-million dollars in the project, which could extend the life of the mine by 25 years, and add 75 more jobs to the 400-person payroll.
Tribal leaders, environmental groups, and the federal government expressed concerns about wild rice, loss of wetlands, possible pollution of private wells, and air pollution that could affect Voyageurs National Park and the Boundary Waters Wilderness.
The U.S. Army Corps of Engineers will make a separate decision on the study.
Keetac workers are just going back to work at the existing mine, after a year-long shutdown.