miningreview
D
own on the sea floor two
house-sized robots are hard at
work. They grab for traction on
sand and rock as their boommounted cutting heads gouge out a ledge
for other robots to work on. Then the bulk
cutters move in to churn up the rock face.
Eager collector machines are next, with
belts of inward-facing teeth to draw the
slurry to pumps, which force the mixture
of rock and water to the surface through
a rigid pipe. So far, no humans.
Above sea level, on a bobbing
headquarters vessel somewhere not far
from Australia, the slurry is separated,
with the hard stuff loaded onto a barge
for the 50-kilometre journey to the port
of Rabaul, Papua New Guinea, while the
cloudy sea water is pumped back down
to the absolute depths.
If Canadian miner Nautilus Minerals
gets to move ahead with its proposal to
"extract high-grade Seafloor Massive
Sulphide (SMS) systems" to produce
copper and gold, that's how its mining
operation will work. But trouble onshore
has put everything on hold as Nautilus
Minerals and the PNG Government
negotiate the small matter of cost sharing.
Everything ground to a halt in November.
Nautilus Minerals is after deposits
formed along hydrothermal vents that
spew out concentrations of minerals and
metals. Such deposits can be as much as
10 times more concentrated than those
found above ground.
"The minerals found on the sea floor
are the same as those found on land,"
says Stefan Williams, an associate
professor at The University of Sydney's
Australian Centre for Field Robotics.
"The concentrations can be higher on the
sea floor in some areas as the minerals are
expelled from hydrothermal vents and then
accumulate around these structures."
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