Minerals Report - International Seabed Authority

• The distance between the mining site and a port, where a processing
plant could be based, is at least 2 500 km (West Coast of Central
America); and
• The mining site is made up of elementary “mine-able fields” averaging
50 km 2 in size (1-5 km E-W on 10-18 km N-S), kilometres apart and flat.
Geostatistical simulations demonstrated that such mine-able fields
could cover 30% of the most promising parts of the French pioneer
area in the north Pacific.
• The average abundance of wet nodules in those fields is 14 kg m -2 ;
• The ratio of dry to wet nodule weight is 0.7;
• The average metal contents are 30% Mn, 1.37% Ni, 1.25% Cu, 0.25%
Co.
2.2.2. Cobalt crusts
Encrustations of ferromanganese hydroxides have been found in many
areas of the seafloor, but more particularly, where consolidated sediments and
hard rocks outcrop. Most of them were discovered on seamounts or plateaux
that constitute elevations of the seafloor in abyssal areas. These summits are
frequently linked with volcanic structures and sometimes are sunken atolls.
Since the beginning of the nineteen eighties, ferromanganese crusts
deposits have attracted the attention of explorers, as potential resources for
cobalt. Although several exploration surveys have been carried out in
different parts of the world’s oceans, mostly by scientific institutions, the state
of knowledge is still limited [15-19].
Cobalt-bearing crusts are often associated with low-grade nodules.
Both these deposits have a relatively low manganese to iron ratio (1-2.5) in
comparison to polymetallic nodules of economic interest (4-6). Their nickel
and copper contents are also lower (0.3-1%). While the cobalt content of crusts
can reach 3%, on average it is only 0.6-0.8%, or three to four times greater than
the average cobalt content of "good" nodules (0.25%). Other metals occur as
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