Rosebud Mine will have new owners under court-approved sales by Westmoreland Coal Co.
In terms approved in bankruptcy court Friday, the mine will transfer to Westmoreland's first lien creditors and continue operating.
Under the agreement, the southeast Montana mine will honor the final months of its contract with Colstrip power plant. The Colorado-based coal company and its creditors had attempted to end its coal-supply agreement with the power plant.
Westmoreland mines in New Mexico and Canada were also part of the approved sale.
Rosebud Mine is Westmoreland's biggest producer of thermal coal.
The announcement comes as Westmoreland renegotiates its Absaloka Mine payments to the Crow Tribe downward.
Westmoreland's Savage Mine in Eastern Montana is also losing its largest customer, the Lewis and Clark Generating Station near Sidney.
Westmoreland listed $1.4 billion in debt shortly before filing for bankruptcy last fall.