Abstract Mining of minerals such as polymetallic nodules from the deep-sea floor has been “on-hold” as a result of several factors such as current availability of Cu, Ni, Co and Mn from terrestrial sources and their fluctuating prices. Nonetheless, exploration
for new resources from deep-sea areas and development of technologies for deep-sea mining have been progressing consistently. These, coupled with recent projections of deep-sea minerals as the alternative source for metals and granting of licenses for exploration and mining of seafloor massive
sulfides to private entrepreneurs, indicate the continuing interest and support the perception that such deposits may serve as sources of metals in the 21st century. However, there are several considerations for the sustainable development of deep-sea mining. A typical area of
75,000 km2 with an estimated nodule resource of >200 million tonnes is expected to yield about 54 million tonnes of metals (Mn + Ni + Cu + Co), and the gross in-place value of the metals is estimated to be ∼$21‐42 billion (depending upon the annual rate of mining)
in the 20-year life span of a mine site. The decision on the timing to resume mining of these deposits will be based on the prevalent metal prices and rate of returns on the estimated investment of $1.95 billion as capital expenditure and $9 billion as operating expenditure for
a single deep-sea mining venture. In view of high investment, technological challenges and economic considerations, private-public cooperation could be an effective means to make deep-sea mining a success. This paper analyzes the current status and discusses the economic, technical, technological,
and environmental issues that need to be addressed for sustainable development of deep-sea minerals.
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