Drilling Through Igneous Rock to Rescue the 33 Miners

On August 5, 2010, the San Jose Copper and Gold mine near Copiapó, Chile collapsed trapping 33 miners 2200 feet beneath the surface.  The San Jose mine has been operating for nearly 100 years, and the mining for copper and gold  is located in a granite type of rock diorite.  Diorite has about the same structural properties as granite but, perhaps because of its darker colour and more limited supply, is rarely used as an ornamental and building material.  As such, diorite, like granite are igneous rocks that have cooled to solid rock from liquid magma deep beneath the surface.  Most diorites and granites are composed of quartz, feldspar and mica.

Cross sectional drawing showing the location of the miners and the mine collapse. Source: BBC News

The cross sectional diagram here shows the scale of the miners and rescuer’s problem in that the miners were trapped nearly 800 m beneath the surface.  As shown in the diagram, the collapse of the mine occurred above the trapped miners.  For 17 days, no one knew they were alive.  For 17 days, rescuers bored nine different drills into the igneous rock, and finally on day 17, one of the drills broke into the large cavern sheltering the miners.  Rescuers heard taps to their drill, and then when they lifted the drill from the bore hole, two notes were attached, one stating that “there were 33 of us, and we are all well.”

Here is one reporter’s description of these events:

But the next morning, between 3 a.m. and 4 a.m., the rescue operation had its first breakthrough. Seventeen days after the collapse, one of the drills — a Schramm T685 operated by the Chilean company Terraservice — hit a cavernous space deep inside the mine.

They knew the drill had hit an opening because the air pressure disappeared. The drill was turned off and lowered into the hole.

Then, a distant tapping was felt on the end of the drill. As it was pulled back to the surface, rescuers were stunned to discover two notes tied to the probe.

They were both written by Mario Gomez, the oldest of the miners. One was addressed to his wife, Lilianett Ramirez; the other was a now infamous message that has been reproduced on T-shirts and billboards, written in red letters. It said: “Estamos bien en el refugio los 33,” or “we are fine in the refuge, all 33 of us.”

After initial contact was made with the miners in August, two of the three small drill holes were converted into lifelines for the trapped men. For the past two months, two of these those holes have been used to send materials and food down to the miners in plastic tubes nicknamed palomas, or doves. Everything the miners need to survive has had to fit through those 14-centimetre openings.

One of the palomas is used for piping water and oxygen into the mine; it has also been threaded with telephone lines and a fibre-optic cable for video conferencing. According to the lead psychologist, Alberto Iturra, some 250 psychiatric experts have contributed to keeping the miners sane, and a doctor from the Chilean army has also been training the men for their final rescue, playing them exercise videos that demonstrate squats and lunges. The miners are also building their pulmonary resistance, singing as they exercise, so doctors will know when they are running short on breath.

The second paloma hole is being used to send down food. The meals have been carefully planned by a nutritionist with the Chilean health ministry in Santiago and the miners are maintaining a diet of about 2,500 calories per day to keep them trim enough for the final rescue.

The third hole that reached the miners in August has become the basis for the Plan B drill, a Schramm T-130.  The Schramm was built by a Pennsylvania company.

Three drilling operations were set into motion; it was Drill B operated by a Chilean company using the Schramm T-130 drill that reached the miners.

To reach the miners, three drilling plans (Drill A, B, & C–see diagram below) were put into practice over a period of several weeks.  It took enormous equipment and massive transportation to bring the equipment and resources needed.  For example it took more than 40 trucks to transport one of the drills, and they had to travel more than 600 miles to the desert like environment of the San Jose Mine.

On day 65, the Schramm T-130 drill broke through with a shaft that was large enough to extract the miners through the rescue shaft using the Phoenix Rescue Capsule.

The capsule was co-designed by NASA and the Chilean Navy.  Three capsules were built for the rescue mission.  The BBC diagram shown below informs us of the detailed preparations that were built into the rescue.

The Phoenix capsule, and "spacesuit-like" outfit was used to rescue and protect the miners on their ascent from the mine. Source: BBC News

Teachers can help students understand the science, and engineering, but more importantly, this rescue underscores the how bravery, collaboration, and trust led to the successful rescue of 33 miners more than two-thousand feet beneath igneous rock.

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About Jack Hassard

Jack Hassard is a writer, a former high school teacher, and Professor Emeritus of Science Education, Georgia State University