Tampa, Florida-based Walter Energy, the leading "pure play" metallurgical coal producer in the world, announced Thursday that Director and CEO Keith Calder has tendered his resignation effective July 31, 2011. In his letter of resignation, Calder said that he is resigning "due to differences of opinion concerning management philosophy."
Joseph B. Leonard will serve as CEO until a replacement is named. In a press release, Walter Energy said that it will search both internally and externally for a permanent CEO.