FILE - The closed LTV Steel taconite plant sits idle near Hoyt Lakes, Minn., Feb. 10, 2016. (AP Photo/Jim Mone, File)FILE - This file photo taken June 15, 2015, shows the Resolution Copper Mining area Shaft #9, right, and Shaft #10, left, that awaits the expansion go ahead in Superior, Ariz. (AP Photo/Ross D. Franklin, File)FILE - In this Oct. 4, 2011, file photo, a prospecting drill rig bores into the bedrock near Ely, Minn., in search of copper, nickel and precious metals that Twin Metals Minnesota LLC, hopes to mine near the Boundary Waters Canoe Area Wilderness in northeastern Minnesota. (AP Photo/Steve Karnowski, File)
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FILE - The closed LTV Steel taconite plant sits idle near Hoyt Lakes, Minn., Feb. 10, 2016. (AP Photo/Jim Mone, File)
