Conditions at the Pike River mine remain "volatile" and are delaying the recovery of the bodies of the 29 men missing inside, police say.
Tasman police district commander Superintendent Gary Knowles said while flames were no longer visible at the vent, conditions inside the mine were still extremely dangerous and
any attempt at a recovery operation was a long way off.
"Even if there is no flame for a period, conditions remain volatile," Mr Knowles said.
"We know the mine is extremely hot - in the range of 600 degrees Celsius. Despite the GAG operating for more than a week now we know there is still oxygen getting into the mine and the risk of further combustion still exists. Our experience to date shows the environment can change very quickly."
Mr Knowles said work was progressing to analyse the risks associated with putting a cap on the vent.
"One of the new risks identified is that capping could cause the GAG to stall and expert advice indicates that would likely prompt further explosions.
Mr Knowles said there was still "a significant quantity of gas escaping" from the vent, which poses risks for helicopters flying overhead.
The next phase would involve using nitrogen-generating equipment to pump the gas into the mine in an attempt to lower the temperature. Machines capable of doing this are available in New Zealand and Australia, and assessments are being carried out as to whether either of these could be operated at the site.
"The situation remains the same. All of the evidence to hand confirms this would be an extremely high-risk operation."
- NZHERALD STAFF
