Ch. 5— Mining and At-Sea Processing Technologies • 185 



OFFSHORE MINING TECHNOLOGIES 



Unless concentrations of mineral deposits off- 

 shore are likely to be much higher than those on 

 land, or unless the values of minerals increase, it 

 is apparent that the mining industry will have less 

 incentive to develop new technology than an indus- 

 try like the petroleum industry. For example, the 

 value of oil from a relatively small offshore field 

 is likely to approach $1 billion. In comparison, a 

 reasonable target for an offshore placer gold deposit 

 might have a value of $100 million — an order of 

 magnitude less. 



Massive sulfides and other primary mineral de- 

 posits of the EEZ may some day present economic 

 targets and offer incentives to development of min- 

 ing technologies. These technologies are likely to 

 depart significantly from dredging concepts and 

 may be more closely related to solution mining, off- 



shore petroleum recovery, or conventional tech- 

 niques of hard rock mining. 



Many of the technological advances made by the 

 offshore petroleum industry would find applications 

 in offshore mining, provided the offshore mineral 

 deposits were rich enough to sustain the capital and 

 operating costs of such developments. This tech- 

 nology transfer was demonstrated during the 1970s 

 when several groups of leading international com- 

 panies in the mining industry sponsored develop- 

 ment work on methods for mining manganese nod- 

 ules from depths of about 15,000 feet. These groups 

 have delayed their plans for dredging nodules, pri- 

 marily because prices for copper, nickel, cobalt, and 

 manganese continue to be low, but also because the 

 institutional regime imposed on the exploitation of 

 the international oceanfloor is still evolving. 



AT-SEA PROCESSING 



Mineral processing involves separating raw ma- 

 terial (ore) from worthless constituents and trans- 

 forming it into intermediate or final mineral prod- 

 ucts. The number and type of steps involved in a 

 particular process may vary considerably depend- 

 ing on the characteristics of the ore and the end 

 product or products to be extracted. Mineral proc- 

 essing encompasses a wide range of techniques from 

 relatively straightforward mechanical operations 

 (beneficiation) to complex chemical procedures. 

 Processing may be needed for one or more of the 

 following tasks: 



1 . To control particle size: This step may be un- 

 dertaken either to make the material more 

 convenient to handle for subsequent process- 

 ing or, as in the case of sized aggregate, to 

 make a final product suitable for sale. 



2. To expose or release constituents for further 

 processing: Exposure and liberation are 

 achieved by size reduction. For cases in which 

 minerals must be separated by physical proc- 

 esses, an adequate amount of freeing of the 

 different minerals from each other is a prereq- 

 uisite. 



3. To control composition: Constituents that 

 would make ore difficult to process chemically 



or would result in an inadequate final prod- 

 uct must be eliminated or partially eliminated 

 (e.g., chromite must be removed from ilme- 

 nite ore in order to meet specifications for pig- 

 ment). Often, an important need is to elimi- 

 nate the bulk of the waste minerals from an 

 ore to produce a concentrate (beneficiation).'" 



Processing of marine minerals may take place 

 either on land or at sea or partly on both land and 

 sea, depending on economic and technological con- 

 siderations. Where processing is to be done wholly 

 or pardy at sea, it is integrated closely with the min- 

 ing operation. However, since almost no mining 

 has taken place to date in the EEZ, offshore proc- 

 essing experience is limited. Processing technology 

 for minerals found on land has developed over 

 many centuries and, in contrast to requirements 

 for offshore processing, has been designed to oper- 

 ate on stable, motionless foundations and, with few 

 exceptions, to use fresh water. 



It is usually not desirable to do all processing of 

 marine minerals offshore. Final recovery may be 

 done onboard in the case of precious minerals, such 



"E.G. Kelly and D.J. Spottiswood, Introduction to Mineral Proc- 

 essing (New York, NY: John Wiley & Sons, 1982), pp. 5-6. 



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