BILLINGS, Mont. (AP) — Montana environmental officials are proposing approval of a major expansion of the state's largest coal mine after it was recently sold through a bankruptcy auction.

Jen Lane with the Montana Department of Environmental Quality said the 72 million ton (65 million metric ton) expansion of the Spring Creek Mine near Decker will occur within the mine's existing permit boundary.

The expansion would extend the life of the mine by four years, to approximately 2031.

Spring Creek in 2017 ranked as the 10th largest coal mine in the United States, producing almost 13 million tons (12 million metric tons) of coal.

A bankruptcy judge on last week approved the sale of Spring Creek and two Wyoming mines owned by bankrupt Cloud Peak Energy to the Navajo Transitional Energy Company.

Company representatives said the sale will help keep the mines open.