Gillette, WY – Arch Coal plans to invest $50 million to reopen a Campbell County coal mine sometime this summer or early fall. The Coal Creek mine has been idle since 2000. It is where Denver-based K-F-x Incorporated has proposed building a plant that to process coal to make it burn more cleanly. The announcement of the re-opening of the mine coincides with record-high coal production and prices in the Powder River Basin. Last year, the basin produced about a third of the nation's coal, or 390 million tons.