210 • Marine Minerals: Exploring Our New Ocean Frontier 



Table 5-9.— Scenario Comparisons: East Coast Placer 



Bureau of Mines (January 1987) OTA 



Deposit kind iimenite, rutile, zircon, etc. in old shorelines llmenite, rutile, zircon, etc. in old shorelines 



Grade Approx. 5% economic heavy minerals by 5 to 15% total heavy minerals (economic % 



v\/eight heavy mineral not specified) 



Size 100 million short tons Not specified 



Distance to shore unloading 

 point 80 nautical miles 100 nautical miles 



Maximum dredging depth 150 feet 120 feet 



Annual mining capacity- 

 tonnage dredged 2.5 to 5.0 million short tons 3.2 to 9.5 million short tons 



Mining system Domestic built new hopper dredge with an Domestic built new hopper dredge with 



onboard new beneficiation plant an onboard beneficiation plant 

 Mining system operating 



days 250 300 



Shore processing plant New, to produce saleable heavy mineral New, to produce saleable heavy mineral 



products products 



Capital costs (million $): 



Dredge 25.9 to 49.7 



Plant and other 16.3 to 24.5 



Total . . . : 42.2 to 74.2 55 to 86 



Direct cash operating 

 costs $U.S. per short ton 

 dredged 4.55 to 3.79 4.72 to 2.2 



Comments (OTA'S) • Technically feasible but economically 



marginal for heavy mineral grades 

 assumed 



• No estimate of accuracy of scenario • Accuracy of scenario not estimated 



• Costs most sensitive to distance from • Costs most sensitive to heavy mineral 

 shore grade 



SOURCE: Office of Tecfinology Assessment, 1987. 



