The honor was given to Willow Lake by the John E Jones Council of the Holmes Safety Association last month.

The mine, Peabody noted, improved its safety rate 65% during the period thanks to expanded safety training, ongoing audits and operational adjustments.

"This past year, Peabody has taken aggressive structural steps to improve our safety processes at Willow Lake, and this honor recognizes the efforts and commitment of the workforce," Midwest senior vice-president of operational Chuck Burggraf said.

"The mine's management team continues to actively engage MSHA, the state of Illinois, the workforce and union representation on safety and compliance awareness and training."

Willow Lake was part of a company-wide effort last year in which mine production was idled so that staff could focus on safety, with an emphasis on hazard recognition, emergency preparedness and best practices.

Peabody said its mines achieved a record year of safety performance in 2010, extending three straight years of improvement in its global safety rate; its incidence rate in the US was less than half the industry average and the company earned more than 10 awards for safety and emergency preparedness.

According to Peabody Energy data, the Saline County operation first shipped coal in 2002 and sold 3.5 million tons of coal in 2009 with a workforce of 450.