Anglo American suspects a “brief ignition event” occurred in the Grosvenor underground coal mine in Queensland during June, in addition to the blast that injured five people earlier in the year.
This was indicated by an elevated reading on June 8, but the event cannot be confirmed as underground access to the mine has remained restricted.
A spokesperson for Anglo American said the suspension of longwall mining elevated the risk of oxidation of the coal in the longwall goaf environment.
Grosvenor personnel were withdrawn from the underground environment last month after an increase in gas levels were recorded, aborting the company’s staged re-entry to the mine in mid-May.
“Since ceasing longwall mining activities on May 6, we have been closely monitoring the resulting levels of various gasses to ensure the ongoing safety and integrity of the mine,” the spokesperson said.
“During normal longwall mining operations, this risk (of oxidation) is very low.
“… The steps we are taking to address the coal oxidisation and heating risk at Grosvenor are tracking as expected, and we believe that the oxidation in the goaf is currently under control.”
Anglo American has continued to work with technical advisors to assess and respond to the ignition event in May.
The accident injured five people, who received burns treatment at the Royal Brisbane and Women’s Hospital.
Production from the longwall metallurgical coal operation at the Grosvenor mine commenced in 2016.
The mine has a nameplate capacity of 7.5 million tonnes a year and a mine life in excess of 30 years.
Anglo American sold its 12 per cent stake in Grosvenor to a Japanese consortium in November last year, equalising its ownership structure at both the Moranbah North and Grosvenor mines.