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By NA UMC

Abstract Booklet

Dec 2, 2023

By NA UMC

Abstract Booklet

Dec 1, 2022

By Tobias Hens, Andrew Frierdich, Joël Brugger

The rapid advancement of green technologies in recent years is closely tied to an ever- increasing demand for raw materials. Innovative forms of zero-emission transportation and sustainable power generation will require a variety of traditional metals such as Ni and Co, but also many non-traditional metals (e.g., REY). Many of these elements are known to be highly enriched in deep-sea ferromanganese (Fe-Mn) nodules and crusts. However, unlocking these metals from their deposits through metal processing is – aside from deposit exploration and production – expected to be a critical component that will affect the overall economics of the marine mining value chain. Hence, research and development of tailored metal processing solutions which can target specific metals of interest in Fe-Mn nodules and crusts, is required. Dynamic mineral recrystallization (DMR) of Fe-Mn oxide phases is a geochemical process that may have notable potential for hydrometallurgical applications. We have recently demonstrated that Ni can effectively be cycled between deep-sea Fe-Mn nodules and crusts and solutions through dynamic mineral recrystallization. DMR occurs in nature as abiotic background process during biogeochemical Mn cycling when dissolved Mn(II) is in direct contact with Mn oxides. Trace metals which are incorporated in the Mn host phases, are cycled between solid phase and solution via coupled dissolution (trace metal release) – reprecipitation (trace metal incorporation) mechanisms.

Jan 1, 2018

By T. Yamazaki, T. Goto, R. Arai, N. Nakatani

The importance of cobalt-rich manganese crusts on the Pacific seamounts for possible future rare metal sources has been recognized these 30 years. The thin layer-type coverage and the micro-topographic undulation of basement affect not only the excavation efficiency but also the economy of mining venture. Because of these distribution characteristics, no economic feasibility has been recognized through the past economic analyses. On the basis of a recent geological study about seamount rocks, a possibility of by-product substrate recovery for phosphorous supply with cobalt-rich manganese crust mining has been highlighted. In the mining model, the substrate rocks are utilized as phosphates for agricultural and chemical usages. Under some preliminary technical and economic assumptions, the possibility of cobalt-rich manganese crust mining venture is examined. The results show a better economy of the venture including the substrate rock usage for phosphorous supply. Introduction Cobalt-rich Manganese Crusts and the Economic Feasibility Cobalt-rich manganese crusts on the Pacific seamounts received attention as potential sources for strategic metals such as Co, Ni, Cu, and Mn, due to their vast distribution and higher cobalt concentration than manganese nodules (Cronan, 1980; Halbach, 1982; Manheim, 1986). In the earlier stage, the geological distribution characteristics were reported (Cronan, 1984; Clark et al., 1984; Misawa et al., 1987; Pichocki and Hoffert, 1987) and a systematic feasibility of the mining was studied (Hawaii DPED, 1987).

Jan 1, 2018

By Paulo Chaves, Márcia Gonçalves, João R. S. Carvalho, Fernando J. A. S. Barriga, Edgar Carrolo, Tiago Luna, Ricardo Rato, Anabela Bento

INTRODUCTION For the last decades, deep-sea marine resources such as seabed massive sulfides (SMS), polymetallic nodules and ferromanganese crusts (Fe-Mn crusts) have received an ever- increasing amount of attention worldwide for their abundance in critical metals and potential commercial value. This interest has mostly been driven by the growing world demand for raw materials, in particular for high- and green-technology applications (e.g., hybrid and electric cars, batteries, photovoltaic solar cells, cell phones, super magnets), as well as by industrialized countries governments other than BRICS states need to secure a more diversified supply of metals, resulting in a new deep ocean exploration boom. Since the oceans and its resources are increasingly seen as indispensable for humans needs and their challenges in the decades to come, this boom increments pressure on marine areas, either in international or within countries economic exclusive zone (EEZ). Since 2002, the International Seabed Authority (ISA) has signed up 29 contracts with several entities and national governments from multiple countries (e.g., Japan, China, Germany, France, Russia, India, Rep. of Korea, UK, Canada, Brazil) for exploration for deep-sea mineral resources in international waters, either for scientific or commercial proposes, which together cover over 1.3 million km2 [1]. In turn, over 300 exploration licenses, covering more than 650,000 km2, have been granted within the EEZ of Pacific countries such as Papua New Guinea, Tonga, Fiji, Solomon Islands and Vanuatu [2, 3]. This number is expected to increase very rapidly, as 77 countries have proposed to the United Nations the extension of their continental shelf in order to extend their EEZ and jurisdiction over potential deep-sea mineral resources [4]. Its estimated that 42% of the potential areas for SMS occurrences, 54% for cobalt-rich Fe-Mn crusts, and 19% for polymetallic nodules lie within the EEZ of coastal countries [5]. In addition, a huge amount of seafloor is yet to be explored and evaluated. Combined, the size of the granted exploration areas represents less than 10% of the overall area thought as most favorable for the occurrence of the 3 types of deep-sea mineral resources above mentioned. This means that today’s assessments on deep-sea mineral resources are only a rough approximation.

Jan 1, 2018

By Richard Harrison, Frank Lim

Deepsea Mining will soon become a reality with Nautilus Minerals getting their equipment ready to mine SMS at Solwara 1 off the coast of Papua New Guinea. The vertical transport system (VTS) adopted by Nautilus consists of a riser hanging ‘freely’ from the mining production vessel with a lifting pump unit suspended at its lower end. A compliant jumper connects the pump to the seabed crawler without restraining its movements. In this free-hanging VTS arrangement, the vessel can be re-positioned to follow the crawler should it want to extend the mining area and start stretching the jumper. A recently proposed alternative to this is a free-standing VTS whereby the riser is grounded on the seabed with a base and maintained in an upright position by distributed buoyancy modules or a buoyancy tank at the top. A compliant jumper connects the seabed crawler to the riser base, and another connects the riser top to the vessel. In this free-standing arrangement, the entire VTS can be lifted clear of the seabed for relocation to a new mining area. This paper will describe the important features of the two options and discuss the advantages and disadvantages in respect of riser dynamic behavior, water depth, weather and mining windows, pump maintenance, installation and retrieval, continency measures, etc. The two systems will also be appraised separately for mining SMS and SMnN deposits.

Jan 1, 2018

By Wiebe Boomsma

INTRODUCTION Starting in February 2014, 19 partners from EU industry, research institutions and academia joined forces and formed the Blue Mining consortium. In the following four years, they have set out to work on the development of deep sea mining technology, looking into exploration, identification, economic assessment and vertical transport systems for the mining of seafloor massive sulphides and polymetallic nodules. In the beginning 2018 this research & development project has come to an end. The Blue Mining project was one of the first EU subsidised projects embracing the TRL system. This system describes a method of de-risking technology using a simple 9-step approach. This method requires experimental testing in laboratory and relevant environments to be able to reach the higher levels (TRL>5) This paper will discuss the progress in development of the vertical transport system, with a focus on the performed experimental work. This paper will discuss three topics: • Booster station technology • Riser dynamics • Vertical hydraulic transport process. BOOSTER STATION TECHNOLOGY Deep knowledge of transport processes is a prerequisite for a clog free vertical transport One of the key technologies in the VTS is the booster station. The centrifugal pump booster station concept is developed in Blue Mining, it consists of two centrifugal pumps and multiple valves, assembled in member-type frame. Deep sea conditions pose special requirements on all components due to the extreme pressures at large water depths. In the Blue Mining project a Deep Sea Special Motor has been developed and tested in laboratory and in the field. The motor is completely filled, lubricated and cooled using seawater due to its unique open structure, furthermore it does not require any lubricants minimizing the environmental pressure of the motor. The motor is first extensively tested in a laboratory, after these tests have been concluded successfully, the motor is shipped to Norway where it has been successfully tested for more than 100 hours at 425 meter water depth.

Jan 1, 2018

By Georgy Cherkashov, Tamara Stepanova, Anna Firstova

INTRODUCTION High tellurium contents in the ancient volcanogenic massive sulfides (VMS) and modern seafloor massive sulfides (SMS) have been reported by V.Maslennikov (Maslennikov et al., 2013). However findings of tellurium minerals in SMS are rather rare. The only reported coloradoite and bi-melonite, have been found in massive sulfides from Rainbow hydrothermal field (Fouquet, 2010). Here we present data about Te - minerals in sulfide chimneys of different ages (up to 84.7 kyr - Cherkashov et al., 2010 ) from Semyenov-2 hydrothermal field. The obtained results The Semyenov hydrothermal cluster was discovered and studied in the course of cruises 30 and 32 of R/V Professor Logachev (2007 and 2009) at 13º31´ N, MAR. This area is associated with an oceanic core complex and associated with serpentinized gabbro- peridotites and basalts. Plagiogranites and tonalites have been dredged on seafloor in the Semyenov cluster area (Cherkashov et al., 2013; Pertsev et al., 2012). In total, 25 sulfides samples have been studied. The major and minor mineralogical phases were identified using reflected light microscope. Major element compositions of ore- forming minerals were analyzed on a Hitachi S3400N scanning electron microscope at the Geomodel Center, St. Petersburg State University (St. Petersburg, Russia) with an AzTec Energy 350 (EDX) detector and an INCA 500 (WDX) detector.

Jan 1, 2018

By John Parianos, Simon Richards

SUMMARY The Clarion Clipperton Zone (CCZ) hosts the most valuable deposit of polymetallic nodules yet discovered. Understanding the geology of this deposit is key to its effective exploration and mining. Nautilus Minerals (via its subsidiary Tonga Offshore Mining Limited; TOML) has been progressing its understanding of the relationship between seafloor morphology/structure and nodule abundance/morphology, both locally (within its contract areas), and globally (across the CCZ and the span of its contract areas of almost 70% of the CCZ). We present the first results of a project with the aim of developing a method to quickly and accurately map seafloor morphology/structure (Tectonic Subcomponent scale) without the necessity for high resolution seafloor multibeam data. Furthermore, the results presented here will allow a first attempt in understanding the relationship between seafloor geomorphologically-defined zones and plate-scale tectonics of the CCZ and adjacent plate segments. INTRODUCTION A relationship between the type of geochemical active layer and nodule abundance/morphology has long been understood (ISA, 2010). Consideration of the range of differing nodule types found within, but especially between, the TOML contract areas allowed Parianos and Pomee (2017) to refine this relationship further via interpreted thickness and dynamism of the geochemically active layer. The scale of the deposit, both in terms of space and time is staggering (a 10-20 cm thick deposit, spanning almost 4500 km, varying within a circa 10 Ma period), but a segment wide geological map may one day prove to reflect controls on nodule formation and distribution.

Jan 1, 2018

By Lénaick Menot, Anne-Sophie Alix, Charline Guérin, Sébastien Ybert, Ewan Pelleter, Florian Besson

Ifremer, on behalf of the French government, holds an Exploration Contract with the ISA for polymetallic nodules in the CCFZ. As part of its exploration activities, the NODULE (2015) cruise was conducted to acquire a 50 m resolution bathymetric coverage of the eastern sectors of the Contract. In 2017, Ifremer initiated an update of the Contract’s mineral resource estimate. Metal grades and nodule abundance were modelled using ordinary kriging. The inferred mineral resource is 436 Mt (wet) of polymetallic nodules at an average abundance of 10.7 kg/m² with a cut-off grade of 7 kg/m². Based on the geological data, seamounts, sedimentary basins and steep slopes contain no nodules. Technical studies of most of the contractors have determined that nodule collectors could not maneuver on slopes above 5 to 10°. Thus, Ifremer has selected a quite conservative slope threshold of 7 % (about 4°) and a backscatter threshold of -29.5 dB to delineate nodule-free areas. This has a significant impact on the resource estimate, as about 54 % of the eastern Contract areas are excluded. Near-seafloor high-resolution mapping and photographic transects, associated with finer-spaced box-core sampling could constitute a next step to better constrain the mineable areas and to get a higher level of confidence in the resource estimation.

Jan 1, 2018

By Frans van Grunsven, Cees van Rhee, Geert Keetels

One of the obstacles during the initial phases of project development is the assessment of the environmental impact. Mining residue, consisting of fine seafloor sediments, are to be discharged subsea to mitigate the impact of these suspended particles. In order to test the effectiveness of discharging in proximity of the seabed, a numerical model is developed within the open source software package OpenFoam. Dedicated laboratory experiments for numerical model validation are discussed within this paper. INTRODUCTION Siltation is considered one of the major pressures on the environment for a seabed mining operation. Siltation is defined as the pollution of water by a high concentration of suspended sediments like clay or silt. This can be caused by two main activities during the mining process: the spill loss during the excavation and the return flow of undesired seafloor sediment after ore filtration on the ship. In a concentrated cloud, these fine particles form a so-called turbidity plume. Prediction of the size of these plumes and the created layer thickness of deposited sediment is a crucial part of the environmental impact assessment. The challenge in predicting the behaviour of these plumes is found in the wide range of scales involved in the process. At the point of origin, the turbidity plumes spread mainly under the influence of turbulent whirls created by an initial momentum and a buoyancy difference due to the presence of the suspended sediment particles. If carried by ambientcurrents, these plumes can spread for several kilometres before blending in the background.

Jan 1, 2018

By Cees van Rhee, Rudy Helmons

INTRODUCTION Seafloor Massive Sulphides are typically found near the oceanic ridges at larger water depths (>1km). The physical properties of SMS, as shown in table 1, are comparable to the properties of weak rock. One of the technical challenges to enable extraction from these locations is the cutting or excavation process. Experiments have shown that the energy needed to excavate the material may increase with water depth (Alvarez Grima et al. 2015). Besides that, it is demonstrated that rock that fails brittle in atmospheric conditions can fail more or less in a plastic fashion when present in a high pressure environment, as would be the case at large water depths. The goal of this research is to identify the physics of the cutting process and to develop this into a model in which the effect of hydrostatic and pore pressures is included. The cutting of rock is initiated by pressing a tool into the rock. As a result, at the tip of the tool a high compressive pressure occurs, which leads to the formation of a crushed zone. Depending on the shape of the tool and the cutting depth, shear failures might emanate from the crushed zone, which will eventually expand as tensile fractures that can reach to the free rock surface. Through this process intact rock will be disintegrated to a granular medium. For an overview of the process (figure 1). Additionally, the presence of water in the pores of and surrounding the rock influences the cutting process through drainage effects. The most relevant effects are weakening when compaction and strengthening when dilation occurs in shearing and tension. Deformation of the rock causes the pore volume to change, resulting in a under or over pressure. As a result, the pore fluid needs to flow. The magnitude of the potential under pressure is limited through cavitation of the pore fluid, limiting further reduction of the pore pressure (figure 2). The drainage effects cause the rock cutting process in a submerged environment to show a stronger dependency of both the hydrostatic pressure as well as the deformation rate (figure 3).

Jan 1, 2018

By Lénaick Menot, Anne-Sophie Alix, Charline Guérin, Sébastien Ybert, Ewan Pelleter, Florian Besson

Ifremer, on behalf of the French government, holds an Exploration Contract with the ISA for polymetallic nodules in the CCFZ. As part of its exploration activities, the NODULE (2015) cruise was conducted to acquire a 50 m resolution bathymetric coverage of the eastern sectors of the Contract. In 2017, Ifremer initiated an update of the Contract’s mineral resource estimate. Metal grades and nodule abundance were modelled using ordinary kriging. The inferred mineral resource is 436 Mt (wet) of polymetallic nodules at an average abundance of 10.7 kg/m² with a cut-off grade of 7 kg/m². Based on the geological data, seamounts, sedimentary basins and steep slopes contain no nodules. Technical studies of most of the contractors have determined that nodule collectors could not maneuver on slopes above 5 to 10°. Thus, Ifremer has selected a quite conservative slope threshold of 7 % (about 4°) and a backscatter threshold of -29.5 dB to delineate nodule-free areas. This has a significant impact on the resource estimate, as about 54 % of the eastern Contract areas are excluded. Near-seafloor high-resolution mapping and photographic transects, associated with finer-spaced box-core sampling could constitute a next step to better constrain the mineable areas and to get a higher level of confidence in the resource estimation.

Jan 1, 2018

By Carlos Almeida, Bruno Matias, Stef Kapuskiak, Eduardo Silva, José Miguel Almeida, Alfredo Martins

Underwater intervention operations have been supported by robotic systems such as remotely operated vehicles (ROV) for a long time. In particular challenging scenarios such as the deep sea, the use of ROV systems for environment awareness is in fact the main tool of choice. With the technical advances in autonomous robotics, there is an increased effort in substitute ROVs whenever possible for autonomous underwater vehicles (AUV). These systems don't have tether and thus provide large advantages from the operations and logistic point of view. However the limited options for underwater communications render them impracticable for many tasks were real time environment awareness and direct human control is needed. Emerging applications in underwater mining, both at sea [1] and in inland flooded mines [2] pose additional requirements in terms of operation support needs and environment restrictions. Two main tasks are to be addressed by assisting robots in these underwater mining operations: providing adequate environment awareness for human operators and obtain precise realtime 3D environment modelling (particularly relevant for the mining planning). The use of ROVs with umbilical cable, has in this case large limitations due to the nature of the mining cutting (performed by dedicated systems) that limit manoeuvrability and pose high risk of cutting the cable or damaging the vehicle. In this paper we present EVA (Exploration VAMOS AUV) an innovative hybrid ROV/AUV system developed for operations support in inland underwater mining operations. This robot is always operated without tether, and the can be used in a wireless ROV tele-operation mode using very short range high bandwidth underwater communication systems and in autonomous AUV mode.

Jan 1, 2018

By Carsten Rühlemann, David Friedmann, Bernd Friedrich, Thomas Kuhn

"This paper explores the option of direct reduction smelting of the nodules from the German license area in the equatorial NE Pacific in a submerged arc furnace (SAF). An optimized slag design is proposed to separate the larger Mn-bearing stream from the valuable metals (i.e. Ni, Cu, Co, Mo). The slag optimization allows a maximum of Mn to be retained in the manganese-silicate slag on the one hand and a maximized metal recovery in a FeNiCuCo alloy on the other. This way, the goal is to make use of the complete nodules (“zero-waste”) instead of extracting only the metals Ni, Cu, and Co, which make up about 3 wt%. The process closely relates to the “Inco Process” by the Ocean Management Inc. (OMI) of the late 1970s, which was a consortium of INCO (International Nickel Company, CAN; today Vale Canada), Preussag AG & Metallgesellschaft AG (GER), DOMCO (JPN), and Sedco (USA). However, the manganese containing slag is investigated in more detail to recover FeMn, FeMnSi and/or SiMn. To optimize the process modern tools such as thermo-chemical modeling in FactSage™ have been used. [1,2]Polymetallic deep-sea manganese nodules may offer a decreased dependency of raw material imports for Germany and the EU. Currently, four European countries (United Kingdom, Belgium, Germany, and France and an Eastern European consortium (InterOcean Metal)) hold exploration licences for these nodules in international waters in the equatorial NE-Pacific. The license areas each cover 75 000 km2 of the seafloor and are located in the Clarion Clipperton Fracture Zone (CCZ) south east off Hawaii at water-depths between 4000 and 6000 m. The nodules may be used as a resource for industrially important metals such as Cu, Ni, Mn as well as for technology metals like Co, Mo, V and Zn. The average chemical composition of nodules from the German license area is presented in Table 1. [3,4]"

Jan 1, 2017

By Mark Vardy, Kasia-Leigh Chidlow, Tim Minshull, Jeorg Bialas, Sven Peterson, Bramley Murton, Alba Gil

Since the discovery of the first black smoker on the East Pacific Rise in 1977 (Francheteau, et al., 1979), the hydrothermal vents, now called seafloor massive sulphides (SMS) deposits, have generated great interest in the geological community, especially regarding their formation and composition. SMS deposits are areas of hard substratum, with high base metal and sulphides content, that form through hydrothermal circulation and are commonly found at hydrothermal vent sites. The high base metal (Fe, Cu, Zn, Pb), sulphur-rich mineral content has interested mining companies, due to their potentially high economic value. Currently, the known SMS deposits do not have the same dimensions as the massive sulphides (MS) found on land (covering just 10s to 100s m2) and pose significant mining challenges (being located in water depths between 800 m and 6000 m), meaning that they do not appear to be economically exploitable at present. However, these deep-sea mineral resources could be important targets in the near future, particularly with our ever-increasing demand for base metals. A key aim of the European Union-funded Blue Mining project is to develop techniques to robustly quantify SMS deposits dimensions (both surface expression and subsurface extent) and therefore assessing the suitability of SMS deposits for future economically viable and environmentally clean deep-sea mining operations.

Jan 1, 2017

By Mark Vardy, Kate Dobson, Isobel Yeo, Paul Lusty, Bramley Murton

In response to anthropogenic climate change, the way in which we use and generate energy is changing. To facilitate these developments, it is essential that we increase and diversify the supply of ‘E-Tech’ elements essential for cleaner energy generation and more efficient usage. The vast majority of these materials (e.g. cobalt, lithium, niobium, platinum group metals, rare earth elements and indium) come almost exclusively from mining and new resources must be found and developed in order to secure supply and meet the demands of the future. Ferromanganese (FeMn) crusts are rich in cobalt, tellurium and rare earth metals, and are common on seafloor hard grounds at water depths over 1000 m. The mining of both FeMn crusts and nodules is potentially viable dependent of the balance of cobalt and nickle prices (Martino & Parson, 2012), however, crusts need to be at least 4 cm thick with cobalt contents of at least 0.8% (International Seabed Authority, 2008). The difficulty for those wishing to exploit these resources is firstly finding them, and secondly assessing their potential remotely. Such capability would not only save time and money, but also allow mining operations to be more focused, reducing needless destruction of seafloor habitats from exploratory mining or mining of noneconomically worthwhile deposits. In this contribution, we examine the distribution of crusts on a single Atlantic Gyot (Tropic Seamount), the morphology of FeMn crusts, their variable growth patterns and the characteristic geophysical response from crusts in various datasets, including ship based 60 m resolution multibeam and high resolution bathymetry, backscatter and sub-bottom profiler data acquired using an Autonomous Underwater Vehicle (AUV).

Jan 1, 2017

By Natalia Konstantinova, Kira Mizell, James R. Hein, Georgy Cherkashov, Amy Gartman, Mariah Mikesell

"Two types of metallic deposits have been found in the deep Arctic Ocean: Hydrothermal Fe, Cu, and Zn sulfide deposits form along Gakkel Ridge in the Eurasia Basin and associated ridges between Greenland and Europe; and iron and manganese oxide crusts (Fe-Mn crusts) and nodules, precipitated from seawater onto rock surfaces in the Amerasia Basin, contain many rare metals of economic interest. Fe-Mn crusts and nodules collected in the Amerasia Basin during 2008, 2009, and 2012 cruises on the USCGC icebreaker Healy are characterized by unique mineral and chemical compositions, very high Fe/Mn ratios, fast growth rates, and other unique characteristics compared to those formed elsewhere in the global ocean. These characteristics reflect temporal and spatial variations in geological, oceanographic, and climatic conditions in the Arctic Ocean and surrounding continents over the past ~15 Myr.RESULTS AND CONCLUSIONSDiscrimination diagrams show that the crusts and nodules found in the Amerasia Basin north of Alaska are hydrogenetic. However, the mineralogy is not typical for hydrogenetic Fe-Mn crusts and nodules, which usually include only amorphous Fe oxyhydroxide and ?-MnO2 (vernadite). The Arctic samples also include the Mn oxides birnessite and 10Å manganates (todorokite, buserite, asbolane), and the Fe minerals also include goethite, lepidocrocite, feroxyhyte, and ferrihydrite. This mineralogy reflects formation under lower oxygen conditions than typical for samples formed elsewhere.The Amerasia Basin crusts have a unique chemical composition compared with crusts from other areas of the global ocean. The key difference is the high Fe contents relative to Mn contents, which determines the types of trace metals hosted by the Fe-Mn oxide phases, and their concentrations. The high Fe/Mn ratios reflect the expansive continental shelves (>50% of the Arctic Ocean) and upper slopes that support redox cycling and release of Fe and other metals to bottom waters, and to the large fluvial input from North America and Siberia. Brine formation on the shelves and currents promote the distribution of the metals throughout the Amerasia Basin, including the deep basins."

Jan 1, 2017

By Peter E. Halbach, Andreas Jahn

Co-rich hydrogenetic ferromanganese crusts are typical marine interface products of growth processes taking place on sediment-free substrate rocks on the seafloor. They grow very slowly and preferentially in water depths below the oxygen-minimum zone (OMZ) and have so far been found even in water depths of up to more than 5000 m, i.e. also below the calcite compensation depth (CCD); these deep ferromanganese crusts are particularly rich in Fe. It is assumed that the O2-minimum zone is the most important source layer of dissolved manganese, the decomposition of fecal pellets here also contributes to this Mn-budget. The process of hydrogenetic precipitation is basically an inorganic colloidal-chemical as well as a surface-chemical mechanism. Microbial mediations can be assumed, in particular since steps of redox-reactions are involved. The two main components of the hydrogenetic substance are hydrated d-MnO2 (vernadite) and x-ray amorphous Fe-oxyhydroxide, both of which are intimately intergrown with each other forming the extremely fine-grained hydrous oxidic material. In seawater, elements occur as dissolved hydrated ions or as inorganic as well as organic complexes which, in general, have either a positive or a negative surface charge depending on the pH of the respective marine environment. These complexes form hydrated colloids that interact with each other or with other dissolved hydrous metal ions. The main agent to oxidize the dissolved Mn2+ ions is oxygen, transported upwards from deeper water by turbulent eddy diffusion and turbulent rise processes at seamount slopes.

Jan 1, 2017

By Sup Hong

"Lifting riser in deep-seabed mining (DSM) is exposed to acute and chronic stresses of materials, whose yield will result in the most critical loss of total mining system. For freehanging riser (FHR), the axial vibration and local bending of riser may produce acute stresses, in the meanwhile, vortex-induced vibration (VIV) in relative current, friction and collisions of solid particles with inner-wall, and material corrosion in seawater are representative causes of chronic stresses. The chronical stresses bring about fatigue failure or abrupt failure by material loss. Hydraulic lifting is effective and promising for transportation of minerals, however, ecofriendly treatment of operating seawater is an unease hurdle to come over. Sizing of riser section confronts multi-directional problems, i.e. safety of slurry transportation (flow assurance), material safety of riser (wall thickness), seawater treatment on board, etc.A free-standing riser (FSR) might exclude a part of design problems of free-hanging riser and give a way to sustainable mining. FSR stands vertically by means of sub-buoyancy part(s). The top of FSR emerges above sea surface and is connected with mining platform through jumper line (supported by external yoke). Total amount of sub-buoyancy and location(s) have to be carefully determined in viewpoints of dynamics of FSI (fluidstructure interaction) in waves and currents. The concept of FSR gives more freedom for design of multi-functional riser system in view of sustainability of DSM. In DSM, sustainability concept may be focused on eco-friendly treatment of seawater and sediment, and safety of total mining system. For feasibility of FSR, however, installation, maintenance and repair need to be investigated thoroughly in collaboration with industry experts"

Jan 1, 2017