Wednesday, the United Mine Workers union filed suit to try to preserve pension and health-care benefits for 10,000 active and retired miners. The lawsuit alleges Peabody Energy and Arch Coal formed Patriot in an effort to get out of their obligation to fund retiree pension and health-care benefits. St. Louis-based Patriot Coal Corp. filed for Chapter 11 bankruptcy protection in July. Patriot Coal CEO Irl Engelhardt, a long-time executive at Peabody, is stepping aside less than five months after taking the job, and 55 year old Bennett Hatfield will succeed Engelhardt. Hatfield became president of the company in May on the same day Engelhardt was named CEO. He had served as chief operating officer since September of last year. He will also take a seat on the board, effective immediately. Hatfield was CEO and a board member at International Coal Group from 2005 until the June 2011 sale of that company. Patriot also announced Wednesday that its finance committee was being absorbed by the full board and that Mark Schroeder, senior vice president of financial planning, was leaving to take a position with a company outside of the coal industry. Michael Scharf was named chairman.