White Rock Quarries, the second-largest quarry in the U.S.,
unveiled its latest high-capacity production tool to hundreds of
business and community guests earlier this year — the world’s
largest aggregate dragline, a Marion 8200 with a 105-cu. yd. bucket.
The bucket is large enough to hold 130 tons of blasted rock. With an average
mining cycle of 75 seconds, the machine can yield 24 million tons of limestone
per year.
Guests got to see the dragline up-close and in action. They donned hard hats,
shuttled to an active pit and boarded the dragline to experience several digging
cycles, then toured the aggregate plant before returning to a tented, catered
luncheon.
Also enjoying the occasion were executives from North American Mining, which
owns and operates the dragline under a mining agreement with White Rock.
Just getting the dragline to White Rock's Miami location was a monumental
task. After disassembly, it was shipped from its previous location in New Mexico
aboard 175 semi-trucks — some with up to 13 axles and 50 wheels — for reassembly
in Miami.
Thirty-five technicians worked 10-hour shifts, seven days a week to finish
the task in a year. The completed unit weighs 6,750,000 lbs. and has a boom
length of 275 feet.
Up and running since September 2005, the dragline makes its way around White
Rock by “walking” seven feet at a time on “shoes” that measure 12-ft. wide by
60-ft. long.
The mammoth machine, which runs on electricity, requires its own nearby,
dedicated power substation.
A python-thick extension cord stretches alongside the quarry’s haul roads to
feed the dragline’s 14 motors, which generate up to 14,500 horsepower to drag,
hoist and swing the bucket, and to propel the unit as it makes its way around
the pit.