MANGANESE NODULES
49
4.2.3 Lifting System
A number of methods have been investigated for transporting
the ore from the sea-floor to the surface. To date, the majority of
work has focussed on a fully enclosed Riser and Lifting System
(RALS), technology from the oil and gas industry. The purpose
of the RALS is to:
• receive themineral ore particles (mined slurry) excavated from
sea-floor deposits by the Seafloor Production Tool/Collector;
• lift the mined slurry vertically to the dewatering plant inlet on
the deck of the PSV, using a Subsea Lift Pump or an Airlift Sys-
tem and a vertical riser system suspended from the PSV; and
• send the return water back to the sea.
4.2.4 Dewatering Plant
The dewatering plant, situated on the PSV, will dewater the
slurry to achieve a transportable moisture level, while min-
imising any material losses. The seawater, which has been
separated from the ore, will likely be discharged back to sea.
The location of the discharge (that is, near the sea-floor or
within the mid-water column) will depend on a number of
factors, including the total water depth, environmental con-
ditions, and cost.
4.2.5 Onshore Logistics / Ore Handling
Ore may either be transported directly from the PSV to market
or, alternatively, taken to a port closer to the mine site. The port
would likely be used for onshore ore handling, stockpiling, and
load-out operations, as well as for storage of spares, equip-
ment, and supplies. If a port is used for unloading and stockpil-
ing, ore will be transferred to bulk carriers for transportation to a
concentrator site or direct delivery to smelters. Ore transporta-
tion, handling, offloading, and stockpiling are well-established
and well-understood operations.
Heath, G. R. (1981). Ferromanganese deposits of the deep sea. Economic
Geology 75th Anniversary Volume, 736- 765.
Shaw, J. L. (1993). Nodule mining-three miles deep! Marine Georesources
and Geotechnology 11, 181-197.
United Nations Industrial Development Organization. (1992). Deep sea-
bed minerals mining and related technology: A status report. Vienna:
UNIDO Marine Industrial Technology Programme.
ISA (2008) Workshop on polymetallic nodule mining technology - current
status and challenges ahead. Background Document. National Insti-
tute of ocean Technology , Chennai India 18 to 22 February 2008.
References
