India's largest coal handling agency - Mjunction

Snap Shot
The concern areas
The miners were trapped at approximately 5 kilometres (3.1
miles) from the mine entrance. What was more worrying was
that the mine had a history of roof instability that had led to
previous roof collapse accidents, including one death. In fact,
a government report warned in July 2010 that the mine owners
had failed "to reinforce the roof". The lack of reinforcement
"had led to [an earlier] collapse of the roof." Till the present
collapse, there had been persistent controversy as to why the
mine was not closed down.
Now, with the discovery of 33 men found alive after 17
days trapped in the mine, the biggest challenge now was the
preservation of their mental health in the months that it could
take to bore a shaft large enough for them to get out.
The rescue plan
With the discovery of the miners being alive, the authorities
put into action the next big plan – that of rescuing the trapped
miners. The President of Chile swung into action and appointed
the man who ran the world's most productive underground
mine, El Teniente, for Chile’s state owned CODELCO copper
company, Andre Sougarret, as the person in charge of the
rescue operation.
The rescue team mobilised three powerful drills, soon to
be known as Plan A, Plan B and Plan C, each with different
methods of pounding through the rock. Plan A was to
drill through the large diameter hole up to the workshop
underground. Plan B was to drill a large diameter hole up
to the refuge chamber, while Plan C focused on drilling a
large diameter hole in between the workshop and the refuse
chamber. The rescuers made it a point to talk to the trapped
miners every day, at first using a phone dropped down the
hole, and eventually by video conference calls.
With three drills advancing towards the men, it was only
a matter of time, before they would have been brought back
Miner coming out of the capsule
to safety. Sougarret calculated the potential speed of each drill
and zeroed in on three dates - December 1 for Plan A to reach
the refuge, October 10 for Plan B to reach the workshop and
October 30 for the shaft in-between for Plan C. In recent weeks,
the miners began to help with the drilling process, taking
shifts to clear away debris that fell into the tunnel of the mine.
Finally, at 8.05 am on October 9, Plan B broke through. The
widened borehole which was 28 inches in diametre was drilled
by the “Schramm T130XD” category drill employed in the
plan and was completed on Saturday, October 9, even though
it was stopped for approximately 10 hours due to a drill-bit
(Tri-cone roller bit used) change. Incidentally, the Schramm
T130XD is a heavy duty, heavy hoist, carrier mounted drill
rig. The T130XD utilises the latest concepts in mast design and
technology. As on October 8, the others namely the Strata 950
had reached 598 metres deep which was equal to 85 percent.
The RIG-422, the only machine which drills a shaft wide
enough immediately, reached 372 metres or 62 percent.
The drilling was done by U.S.-Chilean drilling company
Geotec. A team from Center Rock Inc. of Berlin had built
and managed the piston-driven hammers that pounded the
hole through quartz and silica, some of the hardest and most
abrasive rock in the world.
Health of trapped miners
One of the main concerns was to prevent nausea among the
miners as the rescue capsule was expected to rotate 350 degrees
some 10 to 12 times through curves in the 28-inch-diametre
escape hole on its way up. Physiologists set up obligatory
exercise schedules to keep the men fit for their trying passage
up the escape shaft, when they may have to hold the same
posture for as much as an hour.
A small video camera in the escape capsule was provided,
to be trained on each miner's face so that the person can be
watched as he ascends. The capsule had oxygen cylinders and
masks and also had a two-way voice communication system.
A day after drillers broke through to where the miners had
been huddled together, officials began detailed monitoring
of their health and working out every detail of the half-mile
ascent that was expected to last about 20 minutes for each man.
Special equipment was sent down to measure their heart
rate, their respiration rate and skin temperature.
During the week before the breakthrough, all the miners
underwent underground stress tests to assess their health.
The Chilean authorities called in Dr. J.D. Polk from NASA,
whose expertise lay in treating astronauts in confined spaces.
He instructed the miners to do leg squats, take salt tablets and
protein fluids. Later, doctors transitioned the men to a solid
diet including meat and rice, with a strict 2200-calorie diet to
keep them slim enough to fit in the evacuation shaft just two
feet (66 cm) in diameter.
Officials were concerned about acute hypertension in some
of the miners as well as the opposite, namely sudden drops
in blood pressure in others, due to the speed at which they
would be ascending nearly half a mile to the surface.
COAL INSIGHTS 78 October 2010