Deep Sea Minerals - Vol 2 - Manganese Nodules

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.

References

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.

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