This paper compares the economic feasibility of two deep seabed mining deposits, manganese nodules and cobalt crust using a new quantitative indicator, the cobalt/nickel price ratio, that verifies the equality between the net present value (NPV) of the two resources. NPV is based on two different models, a multi-period and a singleperiod time cash-flow. In both cases results are similar and show that the current price of nickel could produce equality between NPV of manganese nodules and cobalt crust only if the cobalt price were several hundreds dollars per kg. Results are based on cost of mining estimated by Yamazaki for Japanese licensed deposits, and can be used as a guide in the absence of more recent commercially-derived cost models.


Many studies on the economics of deep seabed polymetallic manganese nodules (manganese nodules) have been produced since the end of the 1960s, along with a more recent interest in the potential of cobalt-rich ferromanganese crust (cobalt crust) mining, sustained by the high price of cobalt caused by the political crisis of the major African producers at the end of the 1970s. The private company Nautilus Mineral Inc. is already committed in the commercial exploration of polymetallic sulphides in Papua New Guinea, where the world's first seafloor copper-gold project, Solwara 1, is expected to be operational in 2012. Nonetheless a certain interest in nodules mining is professed by the same private company, whose aim is to start a commercial operation before the end of this decade (Cobalt News, 2008). Following this recent interest in manganese nodules, the object of this paper is to re-open the debate on the economics of mining nodules and crust in the context of mutual exclusivity of these ventures (a condition that makes one venture exclude the other in the first commercial phase).

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