The roof fall came at a time when record prices were being paid for coking coal at upwards of $US250 per tonne and the Queensland coal mining industry was still struggling to recover after the flood and cyclones earlier in the year.

The disruption to production at North Goonyella contributed to a dismal September quarter for Queensland coal, with exports from its main northern terminals dropping to 39.43 million tonnes from 46.95Mt for the same period last year.

Peabody has already estimated that the full year impact of lost production would be up to $US175 million for the mine, which typically produces about 200,000t of coal per month.

The roof fall blocked the main entry to the mine during the completion of a longwall relocation, Peabody said in a statement at the time.

“There were no injuries, and the company immediately contacted relevant agencies to secure re-entry to the mine,” it said. “The company subsequently worked through detailed engineering for the recovery plan, regulatory approvals, discussions with customers and related force majeure notices.”

North Goonyella shipped 2.3Mt to steel-producing customers in 2010.

Peabody also revised its financial targets to reflect these impacts. It now targets third quarter 2011 adjusted diluted earnings per share in the range of $US0.70 to $0.90 and EBITDA of $450 to $550 million, with full-year adjusted diluted earnings per share targets of $3.70 to $4.15 and full-year EBITDA of $2.125 billion to $2.325 billion.

Peabody is still expecting to mine an extra 3.54Mt of hard coking coal from North Goonyella after securing a longwall top coal caving technology licence from Chinese giant Yanzhou Coal earlier this year.

Peabody will work with Yanzhou to ensure the mine's workforce is fully trained and equipped to begin LTCC operations in the first quarter of 2013. The equipment is expected to be placed into service in late 2012.

LTCC technology improves the recoverability of coal over traditional longwall mining methods and will allow the operation to mine the full coal seam thickness of 6.5 metres versus the 4.2m thickness possible with the conventional longwall mining method.