Chile set to launch final operation to free trapped miners

Chilean authorities have begun preparations to launch the final phase of the rescue operation to free 33 miners trapped in a mine since Aug 5.

On Tuesday, three drillers continued to bore down to reach the men some 700 meters underground at the San Jose mine in northern Chile.

At Camp Hope next to the mine, relatives of the miners paid tribute to them by honking the horn of a police patrol car.

Carla Herrera, sister of trapped miner David Herrera, said the "most emotional" moment came Aug 22 when everyone learned that the miners were all still alive after 17 days "of anxiety and of not knowing what had happened".

The T-130 drill, which is being used to pursue Plan B in the three-pronged rescue scheme, is in the best position to reach the miners first and on Tuesday it attained a depth of 466 meters.

However, chief engineer Andre Sougarret said the drilling team had been forced to reduce the diameter of the conduit from 28 inches to 26 inches to limit the wear on the drill bit caused by the hardness of the rock.

Once the conduit is completed, experts intend to insert steel tubing into it to prevent rock from breaking off from the unprotected sides and clogging the tube, although Sougarret said that a final decision had not yet been made on that part of the operation.

"We have to review different alternatives in terms of how the shaft finally is," Sougarret told reporters.

Meanwhile, the drill working on Plan A had reached a depth of 587 meters Tuesday in the first phase of its work.

The RIG 421 oil drill, which is boring a third shaft, had reached a depth of 265 meters.