Deep-sea mining: Economic, technical, technological, and environmental considerations for sustainable development

Mining of minerals such as polymetallic nodules from the deep-sea floor has been ‘on-hold’ due to several factors such as current availability of Cu, Ni, Co, Mn from terrestrial sources and their fluctuating prices. None-the-less, 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 licences for exploration and mining of seafloor massive sulphides 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 a sustainable development of deepsea mining venture. A typical area of 75,000 sq km with an estimated nodule resource of >200 mi t., 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 20 years 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, privatepublic 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 this deep-sea mineral.