Minerals Report - International Seabed Authority

As regard sulphides, the technology is open although leaching methods are
being contemplated.
Dr. Lenoble mentioned that the assumptions for comparative value
were based on the French research programme in respect of polymetallic
nodules in the Clarion-Clipperton Zone. In respect of cobalt-rich crusts, the
study was based on deposits on the Niau atoll. (Tuamotu). In respect of
massive sulphides, he mentioned that there was absence of credible
information and the calculations were based on two sets of values; namely,
the arithmetic mean of metal contents from different sulphides deposits and
secondly, on the data available from the PACMANUS deposits in the Papua
New Guinea. His conclusions were as follows:
The mean values of in situ ores are very similar except in respect of the
sulphides. The cost of mining and processing will make a difference. The
cobalt crust could be mined at 1,000 metres, the massive sulphides at 2,500
metres and the nodules at 5,000 metres. However, the costs were not directly
proportional to the depths and the scale effect could be in favour of nodule
mining that can envisage a higher annual capacity than the other two. Energy
consumption would be more important for scraping and excavating the crusts
and massive sulphides in comparison to harvesting nodules. The risk of
failure of the mining system is another concern. The more complex the
geometry of deposits, the more sophisticated the equipment would be and
correspondingly less reliable. Nodules can be classified as relatively easy
deposits, in comparison to the moderately difficult cobalt crusts and more
difficult sulphides. The protection of the natural environment is another
major concern. Most of the sulphides are discovered in areas of intense
biological activity. Mining might destroy almost entirely such marine life.
Sulphides mining should be authorized only in areas where biological activity
is extinct and such areas are difficult to locate. For the time being he
concluded, no commercial operation is envisaged because the knowledge of
deposits is too poor, mining technology is not available or metal prices are too
low. For some of the deposits, all these conditions exist together. There is no
clear legal regime at present for cobalt crusts and massive sulphides.
INTERNATIONAL SEABED AUTHORITY 45