A Navajo Nation company says it will retain 1,200 employees at three coal mines in Wyoming and Montana that it bought through a bankruptcy auction.

The announcement Thursday came a day after a federal judge gave final approval for the transfer of the mines from bankrupt Cloud Peak Energy to the Navajo Transitional Energy Co.

The purchase makes the Navajo company the third largest coal producer in the United States.

It comes as the industry is reeling from closures of coal-fired power plants across the U.S. Utilities increasingly favor natural gas and renewable energy sources over coal.

The deal covers Wyoming’s Antelope and Cordero Rojo mines Montana’s Spring Creek mine.

Navajo Transitional Energy Co. Chief Executive Clark Moseley says the company has a “solid record of returning mines to profitability.”