Polymetallic nodule mining: innovative concepts for commercialisation

Seabed resources of value to the modern economy include oil and gas reserves, placerdeposits including diamonds and gold, and minerals found in the form of Seafloor MassiveSulfides, Sediments, Crusts and Polymetallic (Manganese) Nodules.A review of the published literature from previous research studies and field trials indicates that polymetallic nodules (PMN) are one of the most attractive marine mineral resources for commercial exploitation. Despite this the review clearly demonstrates a significant gap between the profitability of a PMN mining venture and that necessary to attract commercial investment. The level of investment risk for current polymetallic nodule mining warrants areturn on investment (IRR) of 30-35%. The most optimistic projections for returns at current prices and using current technology are in the range 15-20%. Under these circumstances polymetallic nodule mining will not be commercially viable until risks are reduced or metal prices rise substantially.In light of this finding a review of the technical, environmental, financial and legal-social aspects of marine mining was carried out with a view to identifying opportunities to reduce the level of investment risk.Based on this analysis recommendations are made for technical and strategic decisions that may reduce the investment risk and remove the barrier to commercial seabed mining. Among these recommendations is a new concept for a PMN collector designed for greater efficiency and reduced downtime and a processing system that combines marine nodulefeedstock with land-based laterites.In addition to these two primary concepts a number of other technology-related areas are identified for reducing risk. Principles designed to increase the reliability of a marinemining system are illustrated in the form of ancillary concepts.Finally the underlying principles behind these concepts are summarised and discussed in detail to provide recommendations for potential technology proponents on the various methods to reduce the investment risk confronting marine mining