Pike River rescuers united in desire to recover bodies

NZ Mine Rescue general manager Trevor Watts. Photo / Simon Baker

Mines Rescue workers who wanted to save 29 men trapped underground in the Pike River coal mine remain united in their desire to get their brothers back, their leader says.

All 29 are now deemed dead, after a second massive explosion ripped through Pike River on Wednesday, and a rescue bid has become a recovery operation.

"However long it takes, our men will be there to do their very, very best to recover these guys," New Zealand Mines rescue general manager Trevor Watts said.

They were preparing for a "tough and difficult task", he told Television New Zealand.

"We will minimise the risk as much as we possibly can, but our men are still going to be faced with hostile conditions," said Mr Watts.

There was never an opportunity to enter the mine after the first explosion, as a gas drainage line taking coal seam methane out of the mine had been ruptured.

The severed line was spewing out 800 litres per second of methane, which created an explosive mix in the mine's atmosphere.

Mr Watts declined to speculate on timeframes, but said there were techniques available for reducing the risk of another explosion while a rescue team was in the mine recovering bodies.

Officials are considering a drastic, high-tech strategy to recover the bodies.

A large jet engine which stabilises gases arrived in Hokitika on a Royal New Zealand Air Force Hercules about 6.30am today.

The engine, termed a "GAG unit", has been flown in from Australia, along with 16 crew from the Queensland Mines Rescue Service, to dampen fires and explosive gases in the mine, Queensland Mines Rescue Service manager Wayne Hartley told Radio New Zealand today.

"It's used for controlling underground coalmine fires particularly by inerting the atmosphere and displacing explosive gases or methane gases, extinguishing any fires and suppressing any sparking or sources of ignition," he said this morning.

The Gorniczy Agregat Gasniczy engine is placed at the mouth of a mine. It pumps gas with very low concentrations of oxygen that will not sustain a fire in the mine. Steam is also pumped in. Over time this starves the fire of the oxygen and smothers it.

In 2003 a similar engine was used at the Loveridge Mine in West Virginia to put out a fire that had been burning 200m underground for two months. It took 10 days of continuous use but was months quicker than letting the fire burn itself out.

OPTIONS ON PIKE RIVER

STARVE A FIRE
Starving the tunnel of oxygen would not quench a coal fire because it could exist as heat for a long period before re-igniting.

USING INERT GAS
An "engine" could force gases such as nitrogen or carbon dioxide into the mine to stabilise the atmosphere. Over time this starves the fire of oxygen and eventually smothers it.

FLOOD THE MINE
Difficult at Pike River because the tunnel slopes uphill from the entrance. There is a possibility that water could be poured through the newly drilled borehole. However, this tactic makes the recovery of bodies difficult.