But U.S. Attorney Charles Miller said his investigation is ongoing and did not rule out the possibility that individuals might be charged with violating federal mine safety laws.
''It's our hope this sends a message to the coal industry,'' Miller said. ''It's not our objective to simply punish people ... (but) to deter individuals and corporations from similar conduct.''
He said the charges and fines were the highest ever against a southern West Virginia coal operator.
State and federal investigators say an overheated conveyer belt caused the Jan. 19, 2006, fire at Aracoma Coal Co.'s Alma No. 1 mine.
Two miners - 33-year-old Don Bragg and 47-year-old Ellery Elvis Hatfield - died after they were separated from the rest of their mining crew. Weeks earlier, a mine explosion killed 12 miners at Sago Mine in northern West Virginia, owned by International Coal Group.
Both incidents led to sweeping federal and state mine safety law revisions.
Bragg's and Hatfield's widows attended Tuesday's announcement, but declined comment. Their lawyer, Bruce Stanley, said they hoped the ''penalties will help convince all operators that money will never be more important than miners' lives.''
Last month, Richmond, Va.-based Massey Energy agreed to settle a wrongful death lawsuit filed by the families. The terms of that settlement were not disclosed.
The lawsuit claimed the defendants knew or should have known that a series of problems at the mine, including a missing air control wall, could kill miners by allowing smoke to fill escape routes.
Miller noted that the federal investigation confirmed that air control walls were removed and that Bragg and Hatfield weren't properly trained in how to escape.
Aracoma was charged in a 10-count information, which means the company agreed to plead guilty rather than having the case sent to a grand jury.
The information accuses the company of violating federal safety requirements by failing to provide a primary escapeway for the miners, failure to properly withdraw the miners, failure to train the mine dispatcher on how to monitor the mine's air ventilating system, failure to conduct timely escape drills and providing a false record on when drills were conducted.
A federal district judge will decide whether to accept Aracoma's plea and agreement to pay $2.5 million in criminal penalties and $1.7 million in civil penalties.
Aracoma President John Jones said the company has worked to improve safety at the mine.
''While we will never forget the loss of our two members, resolving these issues with the U.S. Attorney and MSHA will help all of us at Aracoma Coal Company move forward from this tragic accident,'' he said in a statement released by the company.