13/10/10 -The Drilling Technology that brought the Chilean Miners Home
13 October 2010
As the 21 inch diameter Chilean navy-designed steel capsule, the Phoenix, rescues the trapped miners from the Copiapó mine, all praise to the engineering expertise that has contributed to this happy outcome.
It was on August 5 that that the collapse in the gold and copper mine occurred and took another 17 days before a small bore hole established that all the miners were alive albeit 2070 feet below the surface. This is the deepest rescue in history and one of the longest.
That now is history but it is the heroic efforts of the drilling teams, the technology and their expertise that should be highlighted. The challenge for the rescue drillers was the fact that the Chilean mine’s veins of gold and copper ran through quartzite with a high level of abrasive silica. This rock so tough that the drilling team had to employ all their expertise to keep the drill’s hammers from curving off in unwanted directions.
Geotec Boyles Bros., a U.S.-Chilean company, was in charge of the "Plan B" escape shaft, one of three simultaneous drilling efforts that raced to reach the miners. Geotec assembled drillers who were familiar with the key equipment, including engineers from two Pennsylvania companies — Schramm Inc., which makes the T130 drill, and Center Rock Inc., which makes the drill bits. Leading the drilling effort was Jeff Hart, a highly experienced driller who was drilling water wells for the U.S. Army’s forward operating bases in Afghanistan when he got the call to fly to Chile.
Schramm T685 rig drilled the hole that located the miners, and the T130XD rig is being used for Plan B to expedite their rescue. Schramm T130, normally used to bore water wells, is a heavy duty, heavy hoist, carrier mounted drill rig. It used the latest concepts in mast design and technology. Telescoping construction permits long head travel and working height to allow use of Range III casing, yet short overall length in the transport position. With a front overhang of less than 6 feet, the T130XD is suitable for difficult locations when access roads require a compact machine.
The drilling set up was a Schramm T-130 drilling rig, standing more than 145 feet tall with percussion-technology drill from Center Rock that can bore through as much as 131 feet of rock per day, depending on conditions. Center Rock has drilled holes as wide as 10 feet in diameter in the past . In this case, the drill was creating a shaft only 28 inches in diameter – just wide enough to lift a man. The T130 drill aimed at a workshop 2,047 feet (624 meters) below ground. The pneumatic-based drilling system that bored the rescue shaft hole used four hammers instead of just one – similar to the drill that Center Rock used to initially reach the miners with a 12-inch pilot hole.
Center Rock’s pneumatic-driven air compression drills chips away at rock like a jackhammer and several bits were destroyed as the drill made its way to the miners below.
As each miner is returned to the surface, it emphasises the triumph of the human spirit over adversity and the efforts of strangers to save a person in need. Gives you hope and makes you humble.