Laurel Morales/KJZZ

One of the Navajo Generating Station's three 750-megawatt generators.

A Navajo Nation company bought three coal mines in Wyoming and Montana on Thursday in a bankruptcy auction.

The Navajo Transitional Energy Company bought the mines from bankrupt Cloud Peak Energy after a federal judge approved the transfer. The Navajo-owned company says it will retain 1,200 employees at the mines.

The purchase makes Navajo Transitional Energy the third-largest coal producer in the U.S. at a time when the industry is reeling from closures of coal-fired power plants. The Navajo Generating Station is set to close in December, as its operator now favors more economical natural gas.

Navajo Transitional Energy's Clark Moseley said in a statement, the company has a "solid record of returning mines to profitability."

Karl Cates, research editor at the Institute for Energy Economics and Financial Analysis, has been critical of the sale. He joined The Show to explain why.