Armstrong is owned by Yorktown Partners L.P., a private equity firm. It is following in the footsteps of two other small- to mid-sized coal producers—Oxford Resource Partners and Rhino Resource Partners—that completed successful IPOs in 2010. Martin Wilson, Armstrong Energy president, is targeting the end of March for the IPO.

Armstrong Coal is strictly a steam coal producer that operates exclusively, at least for now, in the western Kentucky counties of Muhlenberg, Ohio, Union and Webster. It operates three underground and four surface mines and controls an estimated 319 million tons of proven and probable high-sulfur coal reserves.

Thanks to two new mines, Kronos and Lewis, Armstrong anticipates its production will reach 9 million tons this year, up from 7.2 million tons in 2010. Tonnage amounts for 2011 are not yet available.