Chile's mining minister acknowledged that a problem has stalled the most advanced of three tunnels being drilled to 33 miners trapped underground and said officials might have to restart the bore hole in another location.
But Laurence Golborne insisted Sunday that the setback is within the range of problems foreseen by authorities before the rescue began, and does not significantly alter the expected timeline for getting the men out.
Work on boring the hole stopped last week when a drill struck an iron support beam for a mine shaft at about 900 feet (300 meters), destroying a drill bit. A replacement part was rushed from the United States, but engineers have so far failed to recover all of the broken metal using magnets.
"If we are unable to remove that bit, the hole would not be able to continue," Golborne said late Saturday.
He said authorities planned three bore-holes from the beginning precisely in anticipation of such problems, and he met with relatives of the miners Sunday to assure them that the rescue is still on track Some family members reported that their trapped loved ones sent messages to the surface saying they became concerned when the sound of drilling above them ceased.
"I have heard that (the miners) are showing some worry, but they understand and this has been explained to them," Golborne said.
From the time they first made contact with the miners Aug. 22, some 17 days after the massive underground collapse, authorities have said a rescue could take up to four months. Mining experts have called that timeline conservative, and it apparently takes into account the possibility of setbacks such as the broken drill bit.
Meanwhile a second drill that went offline Friday for routine maintenance resumed operating Sunday.
And workers are busy prepping the so-called Plan C — an oil-well drill so big it took 40 trucks to transport. Crews at the mine had to level rocks and lay a concrete platform over an area nearly the size of a football field on the hilltop, where only a dozen trucks at a time have room to unload.
Taking nearly two weeks just to set up, the Plan C drill will be nearly 150 feet (45 meters) tall when assembled. It is the fastest of the three, capable of reaching the miners in 45 days once it comes online.
The main shaft at the San Jose gold and copper mine in northern Chile collapsed Aug. 5, trapping the miners more than 2,200 feet (688 meters).
Rescuers have opened multiple narrow bore-holes to the miners which they use to pass them food, water, oxygen, electricity and messages.