Minerals Report - International Seabed Authority

he informed participants that in addition to information on the average grade
of deposits, reliable information was also required on the extent (depth) of
these deposits beneath the seafloor along with drill cores in order to make
reliable resource assessments. He pointed out that data on the average grade
of many of the deposits that he had described were based on samples that had
been taken by submersibles, or that were leached, or samples that had been
collected with TV-guided grabs. These samples he further elaborated are all
from the surface. As regards the depths beneath the seafloor of many of these
deposits, he further pointed out that other than the Atlantis II Deep, Middle
Valley and the TAG deposits, at present there is no reliable information on
this parameter for the other known deposits. He emphasized that drilling is
required to obtain representative bulk samples to establish average metal
grade, not only from surface samples but representative samples from drill
cores to arrive at the average grade of the deposit. In this regard he noted that
while the Ocean Drilling Programme had a drill ship, this was not necessarily
the best way to proceed. He suggested that a better approach might be to use
portable drills that could be deployed on ships of opportunity.
Finally he pointed out that 10 out of 12 of the possible mine sites he
earlier identified (Table 6) are located in the Exclusive Economic Zones of
various countries and that only 2 are located in international waters.
Professor Herzig listed some critical factors for mining seafloor
massive sulphides deposits (Table 10). These were reliable size and tonnage
calculations based on drilling and coring; the development and testing of
suitable mining techniques and systems, since there is nothing available at the
present time that could be used for mining seafloor massive sulphides
deposits; economic feasibility studies and analyses, and environmental impact
studies. With regard to environmental impact studies, Professor Herzig said
that mining of seafloor massive sulphides should be limited to deposits to be
found at inactive hydrothermal systems. He described such sites as being
devoid of the fauna to be found at active systems.
He stated that if all these critical factors prove favourable for a deposit,
then there would be a number of advantages to seafloor massive sulphides
mining. The first advantage relating to cost, he said, is that the entire mining
system would be portable, easily moved from one location to another. No
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