Spring Creek underground mine near Greymouth is expected to re-open early next week, after Solid Energy shut it down last Saturday due to fears of a gas-fuelled explosion.
Monitoring equipment had detected the potential for spontaneous combustion in an inaccessible section of the mine. No one has beenunderground since.
South Island operations manager Simon Doig said remote monitoring had shown steady improvement since Monday.
"We have been out of operation for slightly longer than we forecast, but our primary concern has been to ensure that the incident is managed safely. The Department of Labour's Mines inspectorate has been kept informed throughout," he said.
Solid Energy spokesman Bryn Somerville said it was difficult to say exactly how much production had been lost. Spring Creek usually produced about 17,000 tonnes a week, but the mine had scheduled some downtime.
He said Solid Energy had taken steps to minimise the gas problem.
