Deep-sea mining of seafloor massive sulfides and seafloor manganese nodules : deposit modelling and market potential

Aachen (2019) [Dissertation / PhD Thesis]

Page(s): 1 Online-Ressource (ix, 119 Seiten) : Illustrationen, Karten

Abstract

New emerging technologies, a low carbon future and a growing world population will lead to an increasing metal demand in the coming decades. Decline of deposit discoveries on land and decrease in ore grade within the deposits are only some reasons why we need to consider new resources. Deep-sea deposits such as seafloor manganese nodules (SMnN) and seafloor massive sulfides (SMS) hold large quantities of metals such as Cu, Co, Mn, Ni, REE and precious metals. In order to assess these resources, extensive research and exploration are required to quantify deposit dimensions and metal contents. This is more difficult in the deep sea due to technological challenges at great water depths (up to 6.5 km for SMnN) and hence large capital and operational expenditure. In this thesis, two exemplary ore deposits, SMnN and SMS, are analysed and modelled from exploration data to evaluate metal resources, followed by an evaluation of the future deep-sea mining market. The 3D SMS deposit analysed is located along the Mid-Atlantic Ridge (MAR) and is part of the established “Virtual Blue” deposit cluster consisting of 30 deposits with a total tonnage of 40 million tonnes of ore. The reference case was modelled using existing drilling data of a SMS deposit in a back-arc system (Solwara-1) and transferred to a deposit type at the MAR. The modelling focused on the economically most relevant metals Cu, Zn, Ag and Au. Two factors enable the transformation of the Solwara-1 prospect data to the MAR setting, accounting for the intrinsic variation in metal values in the sediment and ore body. Average grades of the Solwara-1 deposit were set in proportion to grades from the Trans-Atlantic Geotraverse (TAG) at the MAR. The result of this analysis is a SMS deposit model with the spatial distribution and geometry of a drilled deposit but with average grades reflecting a deposit at the MAR. Interpolations of the metal values were calculated and a block model was generated to calculate the resources within the deposit of the reference case. A total deposit tonnage of 3.8 Mt was predicted with 3.3 Mt attributed to the ore zone and 0.54 Mt to the sediment body at the surface. The workflow and modelling approach can easily be adjusted with an extended datasets or applied to a different study area. The SMnN deposit area tackled in this study is part of the eastern German exploration license (E1), which is located in the Clarion-Clipperton Zone (CCZ) in the Pacific Ocean. 55 box core samples across a study area of 255 km² contain information about the nodule abundance and metal content of Cu, Ni and Co. Ordinary kriging was used in ArcGIS and resulted in a raster map with nodule abundance (nodules weight per m²), from which the resources of the study area were calculated. The interpolated abundance values range from 10.29 kg/m² to 21.31 kg/m² with an average of 16.51 kg/m² (dry weight). The result is a deposit area with about 4 Mt ore, containing 114,000 t of a combined tonnage for Cu, Ni and Co, and 1,178,000 t for Mn. These calculations of the resource model indicate that the chosen area has a high potential for being mined in the future. This particularly holds due to the low morphological relief of the study area and a nodule abundance larger than 10 kg/m².The analysis and evaluation of the deep-sea mining (DSM) market incorporates multiple scenarios on the future development and includes a short-term (years 2028-2047) and a long-term (years 2048-2067) approach. Focusing on the potential economic turnover for European-based Original Equipment Manufacturers (OEMs), assessments of mineral potential, mining profitability, metal markets, jurisdiction, investments and competitors were undertaken. Contrasting views and projections led to a number of scenarios that are possibly representative of the future development of the DSM sector. Four short-term and seven long-term scenarios were considered, resulting in 0-43 mining projects for SMnN mining and 1-11 projects for mining SMS deposits. The workflow and market analysis tool developed in the course of this analysis can be updated as new information on deep-sea mining enterprises come in and potentially change as the world economy and technology evolves. Key results for the potential turnover from essential mining equipment for OEMs worldwide forecast 2 - 31 billion \$ in the short-term (2028-2047) and a further 23 - 82 billion \$ in the long-term (2048-2067). The workflows and key results of the exemplary ore deposit case studies and the deep-sea mining market evaluation presented in the thesis, can be readily applied in other studies targeting deep-sea mining and other frontier exploration projects.

Authors

Authors

Rahn, Mirjam Christina

Advisors

Kukla, P. A.
Lottermoser, Bernd Georg

Identifier

  • REPORT NUMBER: RWTH-2019-05136

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