The mine went back into production eight days after elevated carbon monoxide levels were found in an abandoned section of the mine. None of the miners were harmed.

The source of carbon monoxide was traced to an abandoned part of the mine, which has since been permanently sealed with concrete barriers. After a final safety inspection company officials, along with state and federal inspectors, signed off on reopening the mine.

“This was a time-intensive project because we took extra precautions to seal off the area and make sure it was completely safe to resume mining,” said Walt Gregory, president of Freeman United.

“The swift, safe evacuation and full remediation of the Crown III mine is a testament to the cooperation of mining experts from the state and federal level, and to the hard work of our miners and safety team at Freeman United,” added Gregory.

All returning miners will participate in a one-hour “stand down for safety” training session covering a variety of safety procedures and practices.

Freeman United also owns the Crown II mine in nearby Virden. The company is owned by defence contractor General Dynamics Corporation.