ST. PAUL — The Minnesota Department of Natural Resources has rejected a request for a full environmental review of a proposed taconite mine expansion in northeastern Minnesota.

Environmentalists argued a more thorough study of the project is needed because the expansion would dig up rocks containing sulfur. Northshore Mining wants to expand its mine near Babbitt in St. Louis County by 108 acres. Parent company Cliffs Natural Resources says that would allow for five to 10 more years of mining.