182 • Marine Minerals: Exploring Our New Ocean Frontier 



Figure 5-12.— Conceptual System for Mining 

 Polymetallic Sulfides 



Riser and 

 air iift pump 



Bottom dredge transported, 

 stored, and handled from 

 semi-submersibie platform. 



Bottom mounted 

 hydraulic dredge 



- Cutter head 



- Dredge pumps 



Platform 



spudded into 



bottom 



A prototype system for mining massive sulfides will unlikely 

 be developed until the economics improve and more is known 

 about the deposits (not to scale). 



SOURCE: R. Kaufman, "Conceptual Approaches for Mining Marine Polymetallic 

 Sulfide Deposits," Marine Technology Society Journal, vol. 19, No. 4. 

 1985. p. 56. 



and finally transported to shore using a tug-barge 

 system. While such approaches seem reasonable 

 given the current state of knowledge, a prototype 

 mining system may be very different. It will not 

 be possible to develop such a system until more is 

 known about the nature of massive sulfides and un- 

 til there is a perceived economic incentive to mine 

 them. 



Cobalt-Rich Ferromanganese Crusts 



Cobalt-rich ferromanganese crusts on Pacific sea- 

 mounts have been known for at least 20 years. 

 However, knowledge that the crusts could some day 

 be an economically exploitable resource is recent, 

 and technology for mining the crusts is no more 

 advanced than technology for mining massive 

 sulfides. 



Despite lack of technology and detailed informa- 

 tion about the resource, a consortium (consisting 

 of Brown & Root of the United States, Preussag 

 AG of West Germany, and Nippon Kokan of Ja- 

 pan) has expressed interest in mining cobalt-rich 

 crusts in the U.S. EEZ surrounding the State of 

 Hawaii and Johnston Island. Most observers ex- 

 pect that crusts, if mined at all, are likely to be 

 mined before sulfides. With this in mind, Hawaii 

 and the U.S. Department of the Interior have re- 

 cently prepared an Environmental Impact State- 

 ment (EIS) in which the resource potential and po- 

 tential environmental impacts of crust mining in 

 the Hawaiian and Johnston Island EEZs are 

 assessed. 



In addition, a relatively detailed mining devel- 

 opment scenario has been prepared as part of the 

 EIS.^ The scenario describes and evaluates the vari- 

 ous subsystems required to mine crusts. A num- 

 ber of approaches are possible for each subsystem, 

 but the basic tasks are the same. Subsystems would 

 be required to fragment, collect, and crush crust 

 and probably to partially separate crust from sub- 

 strate before conveying ore to the surface. The sur- 

 face support vessel and subsystem for pumping ore 



'U.S. Department of the Interior, Minerals Management Service, 

 and State of Hawaii, Department of Planning and Economic Devel- 

 opment, Proposed Marine A'lineraJ Lease Sale in (be Hawaiian 

 Archipelago and Johnston Island Exclusive Economic Zones (Draft 

 Environmental Impact Statement), app. A: "Mining Development 

 Scenario Summary," January 1987. 



