BGR Bundesanstalt für Geowissenschaften und Rohstoffe

Manganese nodule exploration in the German license area

Begin of project: July 19, 2006

End of project: July 18, 2021

Status of project: September 1, 2016

The German industry is fully dependent on the import of metals such as manganese, copper, nickel and cobalt from foreign countries. In view of strong fluctuations in commodity prices, the BGR signed a contract for the exploration of polymetallic nodules in the Central North-eastern Pacific with the International Seabed Authority (ISA) in July 2006. The aim of such exploration in the forefront of industrial exploitation is to secure the supply of the above-mentioned metals to Germany in the long run.

The German license area encompasses a total of 75,000 km2, divided into two regions with 15,000 km2 in the central part and 60,000 km2 in the eastern part of the manganese nodule belt. This deep-sea area located between Hawaii and Mexico has water depths of 4000 to 6000 meters and is densely covered with polymetallic nodules, also called manganese nodules, which are about 3 to 8 centimetres in diameter. They on average contain 30% manganese and about 3% of copper, nickel and cobalt. Especially these last three metals form an important future source of raw material. Further trace metals occurring in economically significant concentrations in the nodules are titanium, molybdenum, lithium and neodymium. The manganese nodule resource in the German license area comprises ca. 900 million tons wet weight, which translates to ca. 600 million tons dry weight.

The regulations on prospecting and exploration of manganese nodules adopted by the ISA require each contractor to gather environmental baseline data during the 15 years exploration phase. Based on such data, the likely effects of possible future mining can be estimated and assessed before intervention within the deep-sea realm actually takes place. Studies of benthic species composition, population densities and connectivity form the most important component of these environmental analyses. In addition to the collection of biological data, detailed analyses of the oceanographic and sedimentological characteristics of the license area must be carried out (e.g. current strengths and directions, particle concentrations in the water column, shear strengths, composition and grain size of the sediment, seafloor topography).

In order to determine the possible effects of future mining on the fauna, contractors should use the above-mentioned baseline data to define pristine areas (Preservation Reference Zones) against which impacted areas (Impact Reference Zones) can be compared. To allow for comparability, both reference zones should have similar species compositions, species densities, nodule abundances and sedimentological characteristics. As the spatial distribution of manganese nodules is not uniform throughout the area, large undisturbed zones will remain in between economically attractive areas. The recolonisation of disturbed areas could then take place from these neighbouring unaffected zones.
As part of the progression of mining operations from exploration to exploitation, each contractor is obliged to submit an Environmental Impact Assessment (EIA) to the ISA before any decision on future mining can be taken. The EIA will include the results of “pilot mining tests” with a nodule collector and the associated comparison of environmental characteristics before and after the test(s). The above-mentioned provisions by the ISA have been designed to safeguard the sustainable use and the effective conservation of the deep-sea realm.

Manganese nodule exploration contract areas in the Pacific (status July 2014)Manganese nodule exploration contract areas in the Pacific (status July 2014) Source: International Seabed Authority (ISA)

The BGR has carried out a total of eight exploration cruises to the German license area between 2008 and 2016. Five of these cruises focussed primarily on detailed analyses of the manganese nodule resource potential and its economic value as well as environmental baseline conditions and biodiversity. A joint French-German cruise was dedicated to the detailed analysis of benthic communities, and two cruises financed by the German Federal Ministry of Education and Research (BMBF) focussed on processes involved in manganese nodule formation.

Two research cruises into the German license area took place on the American research vessel Kilo Moana in 2008 and 2009. These cruises primarily aimed at accomplishing a detailed bathymetric mapping of the seafloor throughout the entire German license area. Moreover, seafloor samples were collected in order to determine the spatial variability in nodule abundance and metal content.

Sea-floor topography of the eastern German license area, looking towards the northSea-floor topography of the eastern German license area, looking towards the north Source: BGR

An expedition with the German research vessel Sonne (supported by BMBF) during the spring of 2010 aimed at carrying out detailed analyses on the genesis of nodule deposits. Another important aspect of this cruise was the preliminary analysis of biodiversity within the license area. Partners in this 3-year research project were the Alfred Wegener Institute for Polar and Marine Research in Bremerhaven (AWI), the Leibniz Institute of Marine Sciences in Kiel (IFM-Geomar), the German Centre for Marine Biodiversity Research in Wilhelmshaven (DZMB), the Centre for Marine Environmental Sciences of the University of Bremen (Marum) and the Max Planck Institute for Marine Microbiology in Bremen.

In the spring of 2012, the joint Franco-German expedition BIONOD took place on the French research vessel L’ATALANTE. This cooperation primarily focused on the comparison of diversity and geographic distribution of faunal species between the French and German exploration license areas, which lie 1300 km apart.

The aim of the three most recent expeditions in 2013, 2014 and 2016, again with the research vessel KILO MOANA, was to localise areas that are especially rich in manganese nodules. In order to investigate the regional variability in nodule abundance and coverage in detail, 168 seafloor samples were obtained from two large prospective areas that cover a total area of ca. 3500 km2. These reference data are currently being evaluated and modelled in terms of total resource estimation. Moreover, an area with a size of 120 km2 was mapped with a resolution of ~1 meter using the deep-towed multibeam system HOMESIDE. This mapping exercise showed that the chosen area is mostly flat and suitable for a test of mining equipment. In this same area, the composition of the benthic fauna was also studied in detail by DZMB throughout four consecutive years, and the variability of bottom water currents was measured in hourly / three-quarter hourly resolution throughout three consecutive years. Based on these preparatory environmental baseline analyses, a pilot mining test could deliver important information on the scale of expected environmental impacts of realistic (industrial-scale) mining scenarios.

The research cruise SO-240 in May/June 2015 with the new research vessel SONNE (financed by BMBF) aimed at analysing low-temperature fluid circulation through the oceanic crust and its potential impact on the chemical composition of pore waters in the above-lying sediments as well as on the formation of manganese nodules. This project “FLUM” ends in July 2017.

Environmental conditions and biodiversity
Biologists from the German Centre for Marine Biodiversity Research (DZMB Senckenberg) in Wilhelmshaven have accompanied all BGR cruises since 2010 and have, in addition to standard morphological analyses, collected a total of ca. 50,000 individual specimens of benthic fauna for the analysis of deep-sea biodiversity in the German license area based on molecular-genetic techniques. The samples which have been analysed so far generally reflect a high faunal abundance and diversity. The inventory of species diversity and population density of the bottom fauna forms an important contribution towards the more regional determination of species range and abundance within the entire manganese nodule belt. Based on such data, that have been collected by different research groups internationally, the ISA established nine preservation areas of 400 x 400 km each (so-called “Areas of Particular Environmental Interest”) in 2012, that together cover ca. 30% of the total area of the manganese nodule belt. These zones should safeguard the biodiversity and unique ecosystem functions of the deep sea within the manganese nodule belt and should enhance the recolonisation of mined areas after possible future mining activities.

Furthermore, the BGR is partner in two large European research projects MIDAS and JPI-Oceans “MiningImpact”, which both focus on the ecological impacts of future mining. The main role of the BGR in the framework of these projects is to evaluate and analyse the dispersion potential of the sediment plume that will develop during mining. BGR data from four Ocean Bottom Moorings show that current speeds at 4000 meter water depth are generally very low (1 to 5 centimetres per second) but that current directions are variable. Current speeds and directions close to the seafloor are controlled mainly by tidal action and but also by surface ocean winds.

Mining concept
The extreme environmental conditions within the salt water environment of the deep sea, with pressures of ca. 500 bar and temperatures of ca. 2°C, necessitate an extremely resistant technology for the mining of manganese nodules. Despite the fact that mining is not likely to start within the next years, the BGR plans on using this time efficiently to support the development of a modern and as environmentally sound as possible technology for the possible future mining of nodules from the deep sea. An important component for such a technology is a self-propelling collector vehicle, such as the one which was developed by Aker Wirth GmbH (now MH Wirth) on behalf of the BGR in 2010. This concept is only one of several possible solutions for the possible future exploitation of nodules. The general aim is to develop a system that is both economically viable and that exerts an as low as possible impact on the environment. Currently, the exploration and environmentally sound mining of marine mineral resources from the deep sea - especially the development of a vertical transportation system and a collector - is advanced by the two European research projects „Blue Mining“ und „Blue Nodules“, both funded by the European Commission.

Model of a collector for manganese nodule mining, developed by Aker Wirth GmbHModel of a collector for manganese nodule mining, developed by Aker Wirth GmbH

Processing and Metallurgy
The total costs of nodule extraction including transport to land as well as their metallurgical processing must, in total, remain distinctly below the commodity prices of metals in the nodules. At the moment this process is still in a developmental stage, making it difficult to estimate the economic feasibility of extraction and treatment. Therefore, at least for manganese nodule mining, the development of an effective metallurgical processing technique in addition to mining technology is of primary importance. Currently the BGR is working together with the RWTH Aachen and the Jacobs University in Bremen on a concept for the extraction of metals from manganese nodules. For these purposes, bioleaching as well as pyro- and hydrometallurgical techniques are being tested at a laboratory scale.



Further information:

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Literature:

Contact 1:

    
Dr. Carsten Rühlemann
Phone: +49-(0)511-643-2412
Fax: +49-(0)511-643-3661

Contact 2:

    
Dr. Thomas Kuhn
Phone: +49-(0)511-643-3780
Fax: +49-(0)511-643-2304

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