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Exploration of Polymetallic Nodules

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A special issue of Minerals (ISSN 2075-163X). This special issue belongs to the section "Mineral Deposits".

Deadline for manuscript submissions: closed (31 May 2021) | Viewed by 47929

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Dr. Pedro Madureira

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Guest Editor

Estrutura de Missão para a Extensão da Plataforma Continental (EMEPC), 2770-047 Paço de Arcos, Portugal
Interests: deep sea mineral resources; deep sea exploration; island formation and evolution; igneous petrology and geochemistry; lithosphere vs. asthenosphere interaction; United Nations Convention on the Law of the Sea

Prof. Dr. Tomasz Abramowski

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Guest Editor

1. General Director of Interoceanmetal Joint Organization, Cyryla i Metodego 9, 71-541 Szczecin, Poland
2. Faculty of Navigation, Maritime University of Szczecin, Wały Chrobrego 1-2, 70-500 Szczecin, Poland
Interests: polymetallic nodules; exploration techniques and data processing; value chain of deep seabed mining; deep sea minerals mining and transport technology; economics of deep sea mining; ocean engineering and energy
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Special Issue Information

Dear Colleagues,

The use of mineral resources has always been critical for the development of new industries, modern technologies, and medical tools. It will be also critical in changing the growth paradigm towards a sustainable economy based on increased efficiency and use of renewable energy resources with the least amount of resource use and environmental harm.

Cobalt, nickel and manganese are considered to be amongst the strategic metals that will play a crucial role in this change. These three metals, plus copper, are found in one promising type of high tonnage mineral deposit: the polymetallic nodules. The nodules are known to occur on the vast abyssal plains at water depths over 4,000 m. They are particularly well known in the Pacific Ocean where they were targeted for commercial extraction during several pilot-mining initiatives that took place in the 70’s of XX century. Most current exploration activities for these deposits are concentrated in the international seafloor named as “the Area” by the United Nations Convention on the Law of the Sea, where the activities are carried out under the jurisdiction of the International Seabed Authority (ISA). Eighteen contracts with the ISA have entered into force for the exploration of polymetallic nodules since 2001. According to the ISA regulations the term “Exploration” means the searching for deposits of polymetallic nodules in the Area with exclusive rights, the analysis of such deposits, the use and testing of recovery systems and equipment, processing facilities and transportation systems and the carrying out of studies of the environmental, technical, economic, commercial and other appropriate factors that must be taken into account in exploitation. Polymetallic nodules are also found in the exclusive economic zones of many coastal states, wherein the above definition can be extended since it reflects the complex and multidisciplinary character of nodules exploration process.

This Special Issue invites contributions dealing with all scientifically focused aspects of polymetallic nodules exploration activities. Particularly, as Guest Editors we expect to contribute to the scientific discussion on how and if the future exploitation of polymetallic nodules may contribute to minimize impacts that will always exists to support the increase and welfare of the human population.

Dr. Pedro Madureira
Dr. Tomasz Abramowski
Guest Editors

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Keywords

Polymetallic nodules
Geological nature of polymetallic nodules
Deep sea exploration techniques
Seabed mapping and exploration data processing
Processing of polymetallic nodules
Estimation of nodule resources and economics
Deep sea fauna in polymetallic nodule deposits
Environmental baseline data
Environmental impact assessment and monitoring systems
Deep sea mining equipment testing

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Published Papers (12 papers)

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Editorial

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3 pages, 177 KiB

Open AccessEditorial

Exploration of Polymetallic Nodules

by Pedro Madureira and Tomasz Abramowski

Minerals 2022, 12(12), 1483; https://doi.org/10.3390/min12121483 - 23 Nov 2022

Cited by 1 | Viewed by 1876

Abstract

The use of mineral resources has always been critical for human development [...] Full article

(This article belongs to the Special Issue Exploration of Polymetallic Nodules)

Research

Jump to: Editorial

33 pages, 18509 KiB

Open AccessArticle

Importance of Spatial Autocorrelation in Machine Learning Modeling of Polymetallic Nodules, Model Uncertainty and Transferability at Local Scale

by Iason-Zois Gazis and Jens Greinert

Minerals 2021, 11(11), 1172; https://doi.org/10.3390/min11111172 - 22 Oct 2021

Cited by 10 | Viewed by 3582

Abstract

Machine learning spatial modeling is used for mapping the distribution of deep-sea polymetallic nodules (PMN). However, the presence and influence of spatial autocorrelation (SAC) have not been extensively studied. SAC can provide information regarding the variable selection before modeling, and it results in erroneous validation performance when ignored. ML models are also problematic when applied in areas far away from the initial training locations, especially if the (new) area to be predicted covers another feature space. Here, we study the spatial distribution of PMN in a geomorphologically heterogeneous area of the Peru Basin, where SAC of PMN exists. The local Moran’s I analysis showed that there are areas with a significantly higher or lower number of PMN, associated with different backscatter values, aspect orientation, and seafloor geomorphological characteristics. A quantile regression forests (QRF) model is used using three cross-validation (CV) techniques (random-, spatial-, and cluster-blocking). We used the recently proposed “Area of Applicability” method to quantify the geographical areas where feature space extrapolation occurs. The results show that QRF predicts well in morphologically similar areas, with spatial block cross-validation being the least unbiased method. Conversely, random-CV overestimates the prediction performance. Under new conditions, the model transferability is reduced even on local scales, highlighting the need for spatial model-based dissimilarity analysis and transferability assessment in new areas. Full article

(This article belongs to the Special Issue Exploration of Polymetallic Nodules)

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37 pages, 33185 KiB

Open AccessArticle

Chemostratigraphic and Textural Indicators of Nucleation and Growth of Polymetallic Nodules from the Clarion-Clipperton Fracture Zone (IOM Claim Area)

by Artur Skowronek, Łukasz Maciąg, Dominik Zawadzki, Agnieszka Strzelecka, Peter Baláž, Kamila Mianowicz, Tomasz Abramowski, Patrik Konečný and Artur Krawcewicz

Minerals 2021, 11(8), 868; https://doi.org/10.3390/min11080868 - 11 Aug 2021

Cited by 12 | Viewed by 3168

Abstract

The detailed mineralogical and microgeochemical characteristics of polymetallic nodules collected from the Interoceanmetal Joint Organization (IOM, Szczecin, Poland) claim area, Eastern Clarion-Clipperton Fracture Zone (CCFZ, Eastern Pacific) were described in this study. The obtained data were applied for the delimitation of nodule growth generations and estimation of the growth ratios (back-stripping using the Co-chronometer method). The applied methods included bulk X-ray powder diffraction (XRD) and electron probe microanalysis (EPMA), providing information about Mn-Fe minerals and clays composing nodules, as well as the geochemical zonation of the growth generations. The analyzed nodules were mostly diagenetic (Mn/Fe > 5), with less influence on the hydrogenous processes, dominated by the presence of 10-Å phyllomanganates represented by todorokite/buserite, additionally mixed with birnessite and vernadite. The specific lithotype (intranodulith), being an integral part of polymetallic nodules, developed as a result of the secondary diagenetic processes of lithification and the cementation of Fe-rich clays (potentially nontronite and Fe-rich smectite), barite, zeolites (Na-phillipsite), bioapatite, biogenic remnants, and detrital material, occurs in holes, microcaverns, and open fractures in between ore colloforms. The contents of ∑(Ni, Cu, and Co) varied from 1.54 to 3.06 wt %. Several remnants of siliceous microorganisms (radiolarians and diatoms) were found to form pseudomorphs. The applied Co-chronometer method indicated that the nodules’ age is mainly Middle Pliocene to Middle Pleistocene, and the growth rates are typical of diagenetic and mixed hydrogenetic–diagenetic (HD) processes. Additionally, few nodules showed suboxic conditions of nucleation. Growth processes in the eastern part of the CCFZ deposit might have been induced with the Plio-Pleistocene changes in the paleooceanographic conditions related to the deglaciation of the Northern Hemisphere. Full article

(This article belongs to the Special Issue Exploration of Polymetallic Nodules)

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27 pages, 13453 KiB

Open AccessFeature PaperEditor’s ChoiceArticle

Exploration of Polymetallic Nodules and Resource Assessment: A Case Study from the German Contract Area in the Clarion-Clipperton Zone of the Tropical Northeast Pacific

by Thomas Kuhn and Carsten Rühlemann

Minerals 2021, 11(6), 618; https://doi.org/10.3390/min11060618 - 9 Jun 2021

Cited by 20 | Viewed by 5890

Abstract

In 2006, the BGR signed a contract with the International Seabed Authority (ISA) for the exploration of polymetallic nodules in the Clarion-Clipperton Zone of the northeast Pacific. During nine expeditions, in particular, “Area E1”, the eastern part of the contract area, with a size of ~60,000 km², was explored in detail. Here, we outline BGR’s exploration methods and provide resource estimates for Area E1 and three sub-areas. The resource assessment is predominantly based on statistical analyses of data obtained by 12-kHz multibeam bathymetry and backscatter mapping, box core sampling and geochemical analysis of nodules. The main parameter for the assessment is the nodule abundance (kg/m²), as its coefficient of variation (CoV) over the entire eastern contract area is relatively high at 36%. In contrast, the metal contents of nodules show only minor variation, with a CoV of 8% for manganese and 8% for the sum of copper, nickel and cobalt. To estimate mineral resources for the entire Area E1, we used an artificial neural network approach with a multivariate statistical correlation between nodule abundance derived from box cores and hydro-acoustic data. The total estimated resources are 540 ± 189 million tonnes (Mt) of dry nodules, and the total estimated metal contents are 168 Mt of manganese, 7.5 Mt of nickel, 6.3 Mt of copper, 0.9 Mt of cobalt, 0.4 Mt of rare-earth elements and 0.3 Mt of molybdenum. A geostatistical resource estimate of three economically prospective areas with a total size of 4498 km², intensively sampled by box cores, was carried out using ordinary kriging of nodule abundance and metal grades. Within these three nodule fields, 7.14 Mt of dry nodules are classified as measured mineral resources covering an area of 489 km². Indicated mineral resources amount to 11.2 Mt, covering an area of 825 km², and inferred mineral resources of 35.5 Mt of dry nodules were estimated for an area of 3184 km². In total, the metal contents of the three prospective areas amount to 16.8 Mt of manganese, 0.74 Mt of nickel, 0.63 Mt of copper and 0.09 Mt of cobalt. Full article

(This article belongs to the Special Issue Exploration of Polymetallic Nodules)

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28 pages, 7504 KiB

Open AccessArticle

Empirical Application of Generalized Rayleigh Distribution for Mineral Resource Estimation of Seabed Polymetallic Nodules

by Gordon Yu and John Parianos

Minerals 2021, 11(5), 449; https://doi.org/10.3390/min11050449 - 23 Apr 2021

Cited by 6 | Viewed by 2089

Abstract

An efficient empirical statistical method is developed to improve the process of mineral resource estimation of seabed polymetallic nodules and is applied to analyze the abundance of seabed polymetallic nodules in the Clarion Clipperton Zone (CCZ). The newly proposed method is based on three hypotheses as the foundation for a model of “idealized nodules”, which was validated by analyzing nodule samples collected from the seabed within the Tonga Offshore Mining Limited (TOML) exploration contract. Once validated, the “idealized nodule” model was used to deduce a set of empirical formulae for predicting the nodule resources, in terms of percentage coverage and abundance. The formulae were then applied to analyzing a total of 188 sets of nodule samples collected across the TOML areas, comprising box-core samples and towed camera images as well as other detailed box-core sample measurements from the literature. Numerical results for nodule abundance and coverage predictions were compared with field measurements, and unbiased agreement has been reached. The new method has the potential to achieve more accurate mineral resource estimation with reduced sample numbers and sizes. They may also have application in improving the efficiency of design and configuration of mining equipment. Full article

(This article belongs to the Special Issue Exploration of Polymetallic Nodules)

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17 pages, 8260 KiB

Open AccessArticle

Application of General Linear Models (GLM) to Assess Nodule Abundance Based on a Photographic Survey (Case Study from IOM Area, Pacific Ocean)

by Monika Wasilewska-Błaszczyk and Jacek Mucha

Minerals 2021, 11(4), 427; https://doi.org/10.3390/min11040427 - 17 Apr 2021

Cited by 6 | Viewed by 2911

Abstract

The success of the future exploitation of the Pacific polymetallic nodule deposits depends on an accurate estimation of their resources, especially in small batches, scheduled for extraction in the short term. The estimation based only on the results of direct seafloor sampling using box corers is burdened with a large error due to the long sampling interval and high variability of the nodule abundance. Therefore, estimations should take into account the results of bottom photograph analyses performed systematically and in large numbers along the course of a research vessel. For photographs taken at the direct sampling sites, the relationship linking the nodule abundance with the independent variables (the percentage of seafloor nodule coverage, the genetic types of nodules in the context of their fraction distribution, and the degree of sediment coverage of nodules) was determined using the general linear model (GLM). Compared to the estimates obtained with a simple linear model linking this parameter only with the seafloor nodule coverage, a significant decrease in the standard prediction error, from 4.2 to 2.5 kg/m², was found. The use of the GLM for the assessment of nodule abundance in individual sites covered by bottom photographs, outside of direct sampling sites, should contribute to a significant increase in the accuracy of the estimation of nodule resources. Full article

(This article belongs to the Special Issue Exploration of Polymetallic Nodules)

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21 pages, 5529 KiB

Open AccessArticle

Structural Economic Assessment of Polymetallic Nodules Mining Project with Updates to Present Market Conditions

by Tomasz Abramowski, Marcin Urbanek and Peter Baláž

Minerals 2021, 11(3), 311; https://doi.org/10.3390/min11030311 - 17 Mar 2021

Cited by 11 | Viewed by 4868

Abstract

This paper presents the economic structure, assumptions, and relations of deep-sea mining project assessment and the results of its evaluation, based on exploration activities and research in the field of geology, mining technology, processing technology, and environmental and legislative studies. The Interoceanmetal Joint Organization (IOM) and cooperating organizations conducted a study incorporating those elements of the project that are recognized as most important for commercial viability. On the basis of formulated financial flow of operating and capital expenses of one processing technology the possible market unit price of polymetallic nodules was estimated and the result is presented in this paper. The rapidly changing economic situation, affected inter alia by the COVID-19 pandemic, is reflected in the study and updated results are based on recent changes in metal prices. Although assumptions related to mining costs need to be confirmed during pilot mining tests, promising results have been shown in the case of the use of high-pressure acid leaching processing technology (HPAL) as well as in the case of raw ore sales. A pre-feasibility study of the project will focus on the two most promising variants of the model. Full article

(This article belongs to the Special Issue Exploration of Polymetallic Nodules)

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19 pages, 4693 KiB

Open AccessArticle

Quantitative Expression of the Burial Phenomenon of Deep Seafloor Manganese Nodules

by Akira Tsune

Minerals 2021, 11(2), 227; https://doi.org/10.3390/min11020227 - 23 Feb 2021

Cited by 7 | Viewed by 2705

Abstract

Manganese (polymetallic) nodules on the deep seafloor in the open ocean have attracted great interest because of their economic potential. Visual data on nodules found on the deep seafloor such as photographs and videos have increased exponentially with the recent progress of related technologies. These data are expected to reflect useful information for estimating these mineral resources, as well as understanding their geological origin. Although the size, number, and coverage of manganese nodules have been measured in seafloor images, the burial of such nodules has not been sufficiently examined. This paper focuses on mathematical expression of the burial of the manganese nodules and attempts to quantitatively elucidate relations among burial degree and nodule geological parameters. The results, that is, a dataset obtained by calculations of relations among parameters, are also utilized for considerations of quantitative expression of burial. These considerations are expected to contribute to a better understanding of the geological origin of manganese nodules. Full article

(This article belongs to the Special Issue Exploration of Polymetallic Nodules)

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22 pages, 4618 KiB

Open AccessArticle

Analysis of the Effect of Payment Mechanism on Exploitation of Polymetallic Nodules in the Area

by Yan Li, Chang Liu, Sihan Su, Mengdan Li and Shaojun Liu

Minerals 2021, 11(2), 221; https://doi.org/10.3390/min11020221 - 21 Feb 2021

Cited by 5 | Viewed by 2868

Abstract

The international seabed area (i.e., the “Area”) is rich in mineral resources. According to the United Nations Convention on the Law of the Sea (UNCLOS) and the relevant implemented agreements, in 2012, the International Seabed Authority (ISA) began to develop the regulations for the exploitation of mineral resources in the Area. The most important part of the regulations involves determining the distribution of benefits from the exploitation of mineral resources in the Area between the ISA and the contractors. The establishment of a financial model to evaluate the economic benefits and compare the distribution scheme was the basic method relied on in the current study of payment mechanism. According to the characteristics of the exploitation project of mineral resources in the Area, the discounted cash flow method was selected to construct the financial model. Taking China’s deep-sea mineral resources development project in the Area as the background, the main parameters of the model were determined. A comparative study of similar financial models with Massachusetts Institute of Technology (MIT) and other foreign countries was carried out, in addition to a sensitivity analysis of parameters. On the basis of the assurance that the contractor’s internal rate of return was not lower than the level of the land mining enterprise, the financial model was used to calculate the internal rate of return and the revenue of royalty under different payment mechanisms and rates. The advantages and disadvantages of different payment mechanisms in the exploitation of mineral resources in the area were analyzed. Lastly, the possible impacts of deep-sea polymetallic nodule mining on Terrestrial metal markets were highlighted. Full article

(This article belongs to the Special Issue Exploration of Polymetallic Nodules)

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13 pages, 3855 KiB

Open AccessArticle

Characterization of Fines Produced by Degradation of Polymetallic Nodules from the Clarion–Clipperton Zone

by Mun Gi Kim, Kiseong Hyeong, Chan Min Yoo, Ji Yeong Lee and Inah Seo

Minerals 2021, 11(2), 205; https://doi.org/10.3390/min11020205 - 15 Feb 2021

Cited by 8 | Viewed by 3232

Abstract

The discharge of fluid–particle mixture tailings can cause serious disturbance to the marine environment in deep-sea mining of polymetallic nodules. Unrecovered nodule fines are one of the key components of the tailings, but little information has been gained on their properties. Here, we report major, trace, and rare earth element compositions of <63 μm particles produced by the experimental degradation of two types of polymetallic nodules from the Clarion–Clipperton Zone. Compared to the bulk nodules, the fines produced are enriched in Al, K, and Fe and depleted in Mn, Co, Ni, As, Mo, and Cd. The deviation from the bulk composition of original nodules is particularly pronounced in the finer fraction of particles. With X-ray diffraction patterns showing a general increase in silicate and aluminosilicates in the fines, the observed trends indicate a significant contribution of sediment particles released from the pores and cracks of nodules. Not only the amount but also the composition of nodule fines is expected to significantly differ depending on the minimum recovery size of particles at the mining vessel. Full article

(This article belongs to the Special Issue Exploration of Polymetallic Nodules)

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33 pages, 12236 KiB

Open AccessArticle

Aspects of Estimation and Reporting of Mineral Resources of Seabed Polymetallic Nodules: A Contemporaneous Case Study

by John Parianos, Ian Lipton and Matthew Nimmo

Minerals 2021, 11(2), 200; https://doi.org/10.3390/min11020200 - 14 Feb 2021

Cited by 16 | Viewed by 5836

Abstract

Exploration of seabed polymetallic nodules identifies the Clarion Clipperton Zone and the Indian Ocean Nodule Field to be of economic interest. Mineral resource estimation is important to the owner of the resource (all of mankind; and managed by the International Seabed Authority; ISA) and to developers (commercial and government groups holding contracts with the ISA). The Committee for Mineral Reserves International Reporting Standards was developed for the land-based minerals industry and adapted in 2015 for ISA-managed nodules. Nodules can be sampled in a meaningful manner using mechanical devices, albeit with minor issues of bias. Grade and moisture content are measured using the established methodology for land-based minerals. Tonnage of resource is determined via the abundance of nodules in kilograms per square metre of seabed. This can be estimated from physical samples and, in some cases, from photographs. Contemporary resource reporting for nodules classify the level of confidence in the estimate, by considering deposit geology, sample geostatistics, etc. The reporting of estimates also addresses reasonable prospects for eventual economic extraction, including factors such as mining technology, the marine environment, metallurgical processing, and metals markets. Other requirements are qualified persons responsible for estimation and reporting, site inspection, and sample chain of custody. Full article

(This article belongs to the Special Issue Exploration of Polymetallic Nodules)

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21 pages, 8523 KiB

Open AccessArticle

Possibilities and Limitations of the Use of Seafloor Photographs for Estimating Polymetallic Nodule Resources—Case Study from IOM Area, Pacific Ocean

by Monika Wasilewska-Błaszczyk and Jacek Mucha

Minerals 2020, 10(12), 1123; https://doi.org/10.3390/min10121123 - 14 Dec 2020

Cited by 13 | Viewed by 5003

Abstract

Direct seafloor sampling using, e.g., box corers is insufficient to obtain an acceptable accuracy of nodule resource estimates in small parts of potential deposits. In order to increase the reliability of the estimates, it was rational to use the results of photographic surveys of the seafloor. However, the estimation of nodule abundance based on seafloor photographs is associated with a number of problems and limitations. The main goal of the study was a statistical analysis of the role and interrelationships of selected factors affecting the accuracy of nodule abundance assessment based on seafloor photographs from the H22 exploration block located in the Interoceanmetal Joint Organization (IOM) area in the Pacific. A statistically significant, but only moderately strong, correlation was found between the abundance of nodules and seafloor nodule coverage (quantitative variables), the nodule abundance and genetic type of nodules (ordinal variable estimated visually from photos), and between seafloor coverage with nodules and sediment coverage of nodules (ordinal variable estimated visually from photos). It was suggested that the nodule abundance could be effectively and more accurately predicted using a general linear model that includes both quantitative and ordinal variables. Full article

(This article belongs to the Special Issue Exploration of Polymetallic Nodules)

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