The operation to dig down to reach the miners could be over by the end of October.
The first to get underway, using a specialist mining drill called a Strata 950 raise bore machine, has proved the slowest. It will cut down to level 100, 702m deep, where the miners are sheltering.
"Phoenix" rescue capsule
- Expected to take 15-20 mins to bring miner to surface
- Three capsules being made
- Designed by Chilean Navy
After creating a pilot hole, the shaft will be widened to enable a rescue capsule to be lowered and raised for each man. As the hole is reamed out to a width of some 70cm, tonnes of debris and rock will fall down the hole.
Engineers estimate that 12 -15 tonnes of rock will need to be cleared by the trapped miners each day. They have at least two functioning trucks in the tunnel and other equipment for moving rubble. Diesel and other materials are being supplied down the various communication shafts.
A second operation - Plan B - started on 5 September using a faster raise bore-type drill, a Schramm T-130, to cut down to level 135, 678m below the surface. The pilot hole reached a workshop a few hundred metres from the miners' refuge on 17 September. The operation was delayed when the drill bit shattered and pieces had to be fished out by large magnets.
The widening process has made steady progress and the shaft could be ready for the rescue operation by mid October.
The third operation - Plan C - started on 20 September using an oil industry machine that will dig level 150, 567m down.
When a shaft is completed, it will be lined with reinforced plastic tubes to keep the sides in place and allow a smoother journey for the rescue capsule. Three rescue capsules, designed by navy engineers, are being made to bring the miners to the surface.
The caged capsules have oxygen on board and a communication system for the miner to speak to the rescuers. In an emergency, the bottom section can be opened, allowing the miner to winch himself back down.