Patriot Coal Corp. wants to limit its obligation to pay retiree health benefits to thousands of U.S. mine workers and their families as part of its plan to survive chapter 11 bankruptcy, Reuters reported yesterday. The company has proposed creating a trust, known as a voluntary employees' beneficiary association, to provide a maximum of $40 million annually up to a limit of $200 million. The annual cost of providing retiree health benefits in 2012 was $71 million and is expected to rise to $73.8 million, nearly twice as much as Patriot has proposed to spend, according to the documents.