Deer Run, which has been fighting a combustion event that first began in March 2015, said the sealing can reduce or eliminate oxygen flow paths as part of its efforts to extinguish the problem.

The producer first asked MSHA for permission to seal the mine on March 1. It had already tried to remedy the issue by sealing specific mining areas, then filling them with inert gas and other extinguishing agents.

Sealing will begin immediately, but Foresight officials said it is uncertain as to when production could resume.

In all, Foresight has four complexes in the Illinois Basin region: Williamson, Sugar Camp, Hillsboro and Macoupin. Deer Run, located in Montgomery County, is part of the Hillsboro complex.