U.S. coal miner Peabody Energy said on Thursday it would wind down a coal mine in southern Illinois, citing diminishing returns and safety concerns. The Willow Lake deposit produced 2.2 million tonnes of coal in 2011 but output has been sharply diminished. Some 400 jobs will be lost as the mine closes. Early this month, a worker died at Willow Lake, and the accident influenced Peabody’s decision of closing the mine.