seabed mining costs from nz project, page-5

Not a claim, trial mining has been done for Namibia.

http://asx.com.au/asxpdf/20090508/pdf/31hhh7g3pfrlbl.pdf

ACN 078 606 434
ASX RELEASE
Friday 8 May 2009
MARINE PHOSPHATE PROJECT UPDATE
Bonaparte Diamond Mines NL (Bonaparte or the Company) (ASX:BON) is pleased to provide an update on further significant developments in the Sandpiper/Meob Phosphate Joint Venture Project, offshore Namibia, namely:
Issue of a Project Assessment Report on proposed dredging operations in the project area, by international dredging company Jan De Nul Group
Renewal of two key exclusive prospecting licences for a further two years
Bonaparte and its Joint Venture (JV) partners, Union Resources Ltd (Union) and Tungeni Investments cc (Tungeni) believe that these developments represent a major advance in confirming the technical and economic viability of dredging the Sandpiper/Meob phosphate deposits as well as in overall risk reduction as the project is advanced towards feasibility.
Proposed Dredging Operations
Union commissioned Jan De Nul Group, a major international dredging contractor, to provide a desktop Project Assessment Report into the viability and estimated cost of offshore dredging based on the characteristics of the Sandpiper/Meob phosphate project. Jan De Nul considered aspects of the dredging and navigational requirements, weather characteristics and port interface in its assessment.
Jan De Nul notes that at this stage of engineering the suction depth of its trailing suction arm dredge vessel, the MV Cristobal Colon can easily be extended to reach 225m water depth. For future detailed engineering, the target depth is set at 250m water depth.
Based on our recently published Inferred Mineral Resource estimate within the project area, there is approximately 132km2 that lies at depths less than 225m in the JV project area containing some 238 million tonnes of Inferred Mineral Resource at an average grade of 17.7% P2O5.
On the basis of an annual campaign of dredging, Jan de Nul has proposed a mining and transporting methodology which delivers material pumped to shore storage for Euros 33 per m3 or US$26* per tonne. The estimate includes pre and post deployment ship modification and mobilization and is based on dredging technology and a vessel currently in operation within the Jan De Nul Group fleet.
The Union announcement of 22 April 2009 containing relevant parts extracted directly from the Jan De Nul Group report are provided in full in Appendix 1.
* Calculated based on a wet bulk density of 1.7t/m3 and exchange rate of 1Euro =US$1.3