Local newspaper the Messenger-Inquirer said the warning notice went to more than just the Midway operation and that there are multiple mines that could potentially close. The producer, however, has not released mine names, noting only that no workers would be employed past January 15.

If a closure occurs at Midway, which has been producing for Armstrong since 2009, up to 135 miners could be out of work.

Armstrong operates seven mines in western Kentucky as well as a dock and preparation facility. Its ILB reserve base is estimated at 560 million tons.

According to company data, Armstrong produced 9.3 million tons from its active operations last year.