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By Akira Usui

The small-scale observations, mapping, sampling, and in-situ experiments have been carried out since 2009 using JAMSTEC ROVs at some model seamounts in the Northwestern Pacific seamounts. Laboratory analysis on mineralogy, chemistry, chronology indicated a continuous slow precipitation since the Middle Miocene, at water-depths 1-6 km, and the modern hydrogenetic precipitation even in the oxygen minimum zones. Thus the variability in abundance and grade of the deposits on regional, small and microscopic scales are determined by geological, geochemical, and hydrological conditions, resulting in the stacked piles of tiny precipitates from the seawaters.

Jan 1, 2018

By Tony van der Steen

Subsea mining system are designed for the following, principally different, tasks: Dreding - The destruction and removal of seabed sediments overlaying the bedrock. Cleaning - The competence of the system to systematically remove the deposits from an undulating hard bedrock with irregular pulleys, channels and fissures. Factors that influence the choice of dredging equipment for a specific project are project requirements such as environmental conditions, location and water depth. However, the most important selection criteria are soil conditions. As a consequence, possible dredging systems, must be evaluated for the following, principally different, characteristics: Dredging proficiency - The destruction of the strata by the equipment. System stability - The capability of the soil to support the subsea equipment The above parameters are determined by the strength characteristics and the bearing capacitv_ of the soil. The author describes the processes involved in excavating the subsea deposits and (transporting the gathered soil as a water-soil mixture to the surface using different excavation and transport methods.

Jan 1, 1998

By David Heydon

The big money is backing both manganese nodules and manganese crusts as the most likely deep ocean mining development by 2010, but seafloor massive sulphides of copper/gold/zinc offer an alternative bet for a start-up by 2010. A study of the ?form guide? or comparison of these resources provides direction on which resources are economic candidates for commercial deep ocean mining development by 2010. This paper covers the commercial and technical issues of exploration, resource definition, drilling/sampling, sea bed mining options, mine plans, environmental issues, legal tenure and capital and operating costs (i.e., profitability) of these two mineral types. Nautilus Minerals has just completed a pre-feasibility engineering study of mining sea floor massive copper/gold/zinc sulphides at 2,000 m depth. The Nautilus study reviewed a range of mining and lifting options, settling on tracked continuous drum cutter miners to produce 2 million tons per annum of high grade ore. Capital costs are shown to be at least 30% lower than a land based copper mine of the same production capacity. Likewise 75% of world?s copper would be produced at a higher operating cost that the proposed seafloor mine. This paper then draws on the Nautilus study for comparison with earlier feasibility studies by others on manganese nodule mining to predict the likely directions in deep ocean mining to 2010.

Jan 1, 2004

By Kurt Aasly, Przemyslaw B. Kowalczuk, Rolf Arne Kleiv

Seafloor massive sulphides (SMS) can serve as a potential resource of metals such as Cu, Zn, Au and Ag. SMS rock samples from the Loki’s Castle area at the Arctic Mid-Ocean Ridge are comprised of sulphide bearing minerals such as pyrite, chalcopyrite, isocubanite, galena, sphalerite, whereas the gangue consists mainly of barite and silica. Sphalerite, chalcopyrite and isocubanite show complex intergrowth textures on the nano- to microscale. Various mineral processing tests were conducted in order to recover copper, zinc and silver. It was shown that sensor-based sorting can be efficiently used for preconcentration of SMS rock samples. A significant amount of waste (i.e. barite and silica) was removed in the preconcentration stage with very low losses of copper and zinc to the waste fraction. The upgraded samples were sent to the next processing stages. The results showed that the complex mineralogy of the SMS material provided challenges to conventional mineral processing methods. Hydrometallurgical processing was applied as an alternative method for extraction of metals from SMS. Leaching experiments were conducted using solutions of different lixiviants, and it was shown that leaching of SMS together with manganese nodules would facilitate efficient recovery of metals from these resources.

Jan 1, 2018

By Sven Petersen

In April 2010 three REMUS6000 series autonomous underwater vehicles (AUVs) have been used to simultaneously map large areas near the Mid-Atlantic Ridge (3°N) axis in water depths ranging from 1,000m to 4,000m. One vehicle was provided by the Leibniz-Institute for Marine Science, IFM-GEOMAR (Kiel, Germany) the other two were provided by the Waitt Institute for Discovery (La Jolla, USA) and managed by the Woods Hole Oceanographic Institute (USA). The REMUS6000 vehicles, manufactured by Hydroid Inc. (USA), are "cigar-shaped" vehicles (4m long and weighing approx. 900kg) and consist of a tapered forward section, a cylindrical midsection and a tapered tail section. An internal titanium strongback, which extends through much of the vehicle length, provides the structural integrity and acts as a mounting platform for syntactic foam, equipment housings, various sensors and release mechanisms. The AUVs can be used in various payload configurations such as multibeam bathymetry, electronic still camera, or subbottom profiler. For these missions the electronic still camera configurations was installed. An EDGETECH 2200M dual frequency (120/410 kHz) side scan sonar was used to map the seafloor, but other frequencies are readily available for more options in resolution and range. The 120 kHz side scan transmitter was used for most missions in order to map large areas (increased range) and to be able to fly at higher altitudes (between 70m and 90m) above the rough seabed encountered in this area. The maximum slant range was between 600m and 700m on both sides resulting in a swath width of up to 1.2 km. Line spacing ranged from nearly 1,000m in flat areas down to 400m in steep terrain. Side-scan mosaics were generated with a 1m resolution. Selected areas were targeted by the higher resolution 410 kHz transmitter as well as by bottom photographs flying as low as a few meters above the seabed. The vehicles navigated autonomously using a combination of inertial navigation (Kearfott T-24 or T-16 INS) and long baseline acoustic navigation by computing their range to two moored acoustic transponders. Working efficiently in this rough topography at speeds above 3 knots was only possible due to the obstacle avoidance capabilities of these AUVs.

Jan 1, 2011

By Anthony Wakefield

Dredging tends to be either horizontal or vertical. In each case solids have to be disengaged from the deposit, mobilized, acquired and elevated or translated. One means of elevation is the airlift. Elevation and translation of essentially granular material nay be by jet pump or centrifugal pump. Any of the three types may be used on its own. The airlift and jet pump may he combined for vertical transport and the centrifugal and jet pumps for predominantly horizontal. Both suction point and pipework must have a means of deployment from the surface or from a submerged vehicle or merely a diver. An airlift is an energetic system, having a source of energy and a means of storing it. It therefore will be difficult to prevent oscillation -surging. A centrifugal pump has a characteristic that bends over at low flow rate and is therefore intrinsically unsuitable for pumping solids. The result is blockage, operation at high velocity and correspondingly high wear rates or operation at low concentration of solids and correspondingly low efficiency. The jet pump is intrinsically exceptionally stable but has a low hydraulic efficiency. The jet pump-airlift hybrid prevents or reduces surging and increases system efficiency away from the optimum depth for airlift operation. Delivered solids concentration is increased. The jet pump-centrifugal pump hybrid totally prevents pipeline blockages and increases the productivity from a given pipeline size. For a given energy input the average production is typically doubled. For example, the Indian River Delaware bypassing pipeline transmits an overall day-in-day-out average of 500t/h (tonnes) of sand down a 10.86" diameter line.

Jan 1, 1998

By Keith Gordon

The recent discoveries of hydrothermal activity in the ocean off New Zealand have created interest in the business community in the commercial possibilities of mining associated marine polymetallic sulfides. This interest is more so, as this hydrothermal activity is in much shallower depths, between 120 ? 1800 meters, than the typical 2400m in other parts of the oceans. Mining for other ocean deposits around NZ, such as phosphate nodules and off-shore deposits from gold bearing river beds is also attracting interest. The question is: - how can these deposits be mined without spending the enormous sums of money required for specialized mining technology? There are no dedicated off- the-shelf systems designed exclusively for underwater mining. Such systems require expensive development and manufacturing processes and then, are most probably designed for only one specific purpose. The costs involved place such equipment beyond the means of smaller entrepreneurial groups and only the big companies have the resources required. However, large companies are normally reluctant to take the risk of investing large sums of money into deep ocean projects. Australia and New Zealand, until recent times, have been somewhat isolated from European and North American technical resources - especially in the field of underwater technology. Over the past century such isolation has often led to solving problems with what has become locally known as ? ?the number 8 gauge wire method?. This approach to problem solving entails using whatever is available to get the job done and keep costs down. In the old days with NZ technology being mainly based around farming, a piece of No. 8 gauge fencing wire, although not designed for the purpose, was often used to fix various problems ? hence the term.

Jan 1, 2002

By Derek Ellis

There are two environmental issues which have only recently begun to need planning in detail for marine mining. One is the environmental consequences of mine closure; the other is environmental terrorism. In principle it is not difficult to predict the pattern and rate of biodiversity recovery after mine closure on metalliferous depositional seabeds. 1-5 years to a self-sustaining community of organisms is a generalized guideline, depending on depth and particulate composition. The rate and pattern of biodiversity recovery on some metalliferous hard-rock habitats is far less predictable due to the patchiness and rareness of the habitat. Ecoterrorism at mines, whether on-land or marine, is now to be expected. A good example of resource industry ecoterrorism is the fire-bombing of logging and cement trucks in Oregon in 2001. But there have also been bombs at mine sites, as at Asbestos, Quebec. It is also possible to regard some resource-loss lawsuits as frivolous, hence forms of ecoharassment. Marine mining operations should take note of the development of environmental terrorism (and terrorism in general) and its various manifestations and impacts. Potentially these range from minor work stoppage inconveniences, to serious financial risk jeopardizing the economics of a mine, to jail for company executives, managers and environmental staff, and to harassment and killing of mine personnel.

Jan 1, 2005

By Jan M. Peter

Many of the Pb-Zn massive sulfide deposits of the Bathurst area in northern New Brunswick, Canada, are intimately associated with laterally continuous iron formation (IF) (Figure 1). This IF is a fossil laminated, exhalative, chemical sediment. Together, the IF and the Brunswick #12, Brunswick #6, and Austin Brook deposits (rightmost discontinuous horizon on Figure 1) are collectively referred to as the "Brunswick Belt". To date we have only studied the Brunswick Belt and have not examined the horizon along which the QSR, CNE and Flat Landing Brook deposits lie. The Bathurst area is underlain by the Tetagouche Group (Figure 2), a Cambro(?)-Ordovician sequence of metasedimentary and bimodal metavolcanic rocks that was intruded by mafic to felsic plutons and subsequently deformed during the Taconic Orogeny. The stratigraphic sequence consists of shales and greywackes that are overlain by carbonaceous shales and felsic volcanic and volcaniclastic rocks; these are in turn overlain by mafic volcanic and sedimentary rocks. The massive sulfide deposits and IF occur within the upper portions of the felsic volcanic rocks in close association with carbnaceous metasedimentary footwall rocks (Figure 2).

Jan 1, 1993

By N. J. Poll

The Zacarias gold-silver-barite deposit appears to be a Precambrian analogue of present-day exhalative deposits on the sea floor. Geochemical, stratigraphic and structural studies of the latter can be useful in elucidating the ore environment at Zacarias, thereby assisting exploration. The Zacarias mine is about 300 km north of Brasilia, within the Goiás Massif, Brazil. It is the southernmost of three auriferous quartzite occurrences along 1 km of a northeasterly striking amphibolite. Zacarias and its neighboring smaller deposit to the north, the Central Pit, contained a premining ore reserve of 650,000 tons at 4.4 g/t gold, 48 g/t silver, and about 20% barite. Gold mineralization is hosted by concordant quartzite strata also containing layered barite, pyrite, barium-mica, sphalerite, galena, chalcopyrite, magnetite, sulfosalts, free gold, and electrum. The host amphibolite is intercalated with barren mica-quartz-chlorite-pyrite schists that are more voluminous in the footwall and are associated with the ore horizons. Above the amphibolite in the hangingwall lies a thin graphitic shale, then a feldspathic arenite. The strata and regional foliation strike northeast and dip 42° northwest. Crenulation and small-scale folds plunge 30 to 40° to the west.

Jan 1, 1993

By Eleanor Martin

An examination of the draft Exploitation Regulations from an investor’s perspective. We will look at the commercial requirements of the investment community (debt and equity) in order to provide funding to a deepsea mining project, and contrast this with the position put forward in the draft Exploitation Regulations. We will then recommend suggested amendments to the Exploitation Regulations to assist future investment on this growing industry.

Jan 1, 2018

By Cheong-Kee Park

Since 1983, Korea Ocean Research and Development Institute (KORDI) have performed surveys on deep-sea mineral deposits in various areas with respects to their occurrences in Pacific ocean including manganese nodules in the C-C area of Northeast Pacific, Co-rich manganese crusts in various seamounts of West Pacific and hydrothermal sulfide deposits in back arc basins of Southwest Pacific. Among the results of these activities of KORDI, remarkable things were the registration as a pioneer investor in 1994 through the Government of Korea and the accomplishment of relinquishment on the allocated area in 2002 according to the relevant regulations. KORDI is faced to handle detailed surveys to select the optimum mining sites in the allocated area of 75,000 km2 and environmental studies to meet the requirements of the regulations or recommendations of the ISA. In respects of future exploration strategies, it is considered that methods and tools of previous exploration activities should be changed to the highly advanced technology. Establishment of an advanced exploration system and actual practice in appropriate areas become one of important tasks of KORDI in exploring deep-sea minerals, particularly manganese nodules. A technical strategy for future detailed surveys in the allocated area is realization of simultaneous and precise data acquisition on bottom information, such as variations of microtopography, nodule distribution, and transparent layer thickness of sediments in relatively small area (10 km x 10 km) representing certain specific regions, by high resolution survey technology. It would be not only a challenge for new exploration system in deep-sea environment, but also a mission for deep seabed mining venture.

Jan 1, 2003

By Amy Gartman

"Seafloor hydrothermal systems result in the emission of abundant particles and nanoparticles into seawater1. Many of the elements in these particles settle locally, although some are transported distally to the global ocean2. Although broad similarities exist, the mineralogy, size and therefore reactivity of particles emitted varies between sites in the global ocean, and even within sites at the same vent field. The particle geochemistry of these vent fields is a critical but little understood component both from a perspective of baseline characterization and potential environmental impacts.The mining of seafloor massive sulfides formed from hydrothermal venting will generate a new class of particulates in the deep ocean. Broadly, black smoke and SMS tailings exhibit similarities including abundant Cu, Fe and Zn sulfides, and a large number of submicron particles. In addition to the major minerals, minor minerals including As, Bi, and Pb are present, especially in back arc settings. However despite broad similarities, natural “black smoke” and crushed sulfides created during mining operations differ significantly in size class, morphology, abundance, and reactivity. A comparison of these two classes of particulates will be presented, including chemical composition and reactivity to dissolution and oxidation."

Jan 1, 2017

By Alexander Malahoff

The new ship-submersible system with R/V Ka'imikai-o-Kanaloa as a mothership and the PISCES V as the submersible completed its first season of dives. The dives involved deployment of the PISCES V in the Hawaiian Islands between the months of July and October 1996. Submersible deployments up to depths of 2,000 meters in sea states up to a high three were made. The new hook and clasp deployment and retrieval connection for PISCES V to the telearm was shown to be an effective system for handling the PISCES V with the A-frame. The shipboard multibeam survey and seawater sampling capability proved to be especially effective in re-mapping the summit of the submarine volcano Loihi following a major volcano-tectonic event and for following the source and configuration of the new hydrothermal plume. Following the earthquake swarm of July 17 to August 18,1996, major changes in the geological setting of Loihi submarine volcano took place. Prior to the seismic event, the geology and structure of the summit of Loihi was represented by a platform-like area 8,100 meters long and 5,400 meters wide enclosed by the 1,200-meter depth contour. The summit was characterized by the presence of two prominent pit craters and eastern and western crater located at water depths of 1,100 and 1,370 meters, respectively. A hydrothermally active volcanic cone, named Pele's Vents, was located at a depth of 960 at the southern edge of the summit. The floor of the summit of Loihi was largely covered by prismatic talus, with interstitial hydrothermal clays. Pillow and tube lavas with volcanic cones 5 to 50 meters high were exposed along the axes of the southern and northern rift zones. The inner margin of the summit displayed fissures and normal faults with the downthrown component towards the center of the summit. The pre-earthquake structural data suggest a pre-caldera structural stage for Loihi. Maximum sustained hydrothermal activity observed on Loihi over the past 10 years existed at Pele's Vents with other sporadic venting occurs along the summit platform and along the south rift. Following the earthquake swarm, the hydrothermally saturated Pele's Vents cone gave way and slid into the inner pit crater. Subsequently, the observed above- bottom hydrothermal plume source deepened from 960 to 1,160 meters, possibly emanating from the same intrusive heat source as Pele's Vents. The observed inward collapse of the summit structures and subsequent opening of fissures gave rise to diffuse venting from the newly formed caldera-like depression with the bottom-hugging hydrothermal pool located at depth between 1,250 and 1,220 meters at the sites of the pit craters.

Jan 1, 1996

By Robert Corcoran, Piotr Jasiobedzki, Roy Jakola, Michael Jenkin

Vast mineral resources of copper, zinc, cobalt and gold have been identified off the coast of Papua New Guinea at depths exceeding 2,000 meters. Accessing them in a cost effective manner and without destroying the marine habitat requires overcoming numerous technical and operational challenges. Although there are a number of deep-sea mining operations underway worldwide, the depths encountered are significantly less than will be required to mine these ore deposits. To date, only the oil industry has developed technologies for successfully accessing reserves at depths of 3,000m.

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 Benoît Waquet

In a context of scarce mineral resources, coupled with an increasing global demand in metals due to the exponential growth of newly industrialized countries, the mining industry will inevitably have to deal with tomorrow?s resources: underwater deposits. Three types of offshore deposits are known to date: polymetallic nodules, cobalt-rich crusts and hydrothermal sulphides. The latter, regarding the political-economic context, is now considered most likely to be exploited in a near future. Operating a mine critically requires accurate knowledge on geotechnical properties of the ore. A question is thus to be asked: Is there a particular spatial organization of geotechnical properties in a hydrothermal sulfide mound? In the present study, geotechnical properties have been measured for 29 sulfide samples of known origin, completed by 14 measurements on Western Pacific specimens from Yamazaki et al. (1990) and Yamazaki and Park (2003). From these geotechnical data on 43 sulfide samples, we can provide some answers to this question above, crucial for future exploitation of underwater mines.

Jan 1, 2010

By Akira Usui, James R. Hein, Rachel Dunham

Ferromanganese crusts are found on most hard-rock substrates in the deep ocean (800-3,000 m). Their distributions on seamounts are complex and controlled by a wide-variety of factors including seamount morphology, current patterns, mass wasting, substrate rock type and age, subsidence history, and others. However, the development of this potential resource ultimately depends on this distribution, as well as on the small-scale topography, grade, and tonnage. The parameters that will ultimately be used to define a mine site are unknown, but reasonable assumptions based on 25 years of data collection can be used to bracket likely permissive characteristics.

By Timothy F. McConachy, Christopher J. Yeats, Ray Binns

Various kinds of sediment-hosted polymetallic sulfide deposit are known on land in ancient marine sequences, many tending to be larger and more valuable than massive sulfide deposits genetically associated with volcanic host rocks. Often such deposits are attributed to subhalative or shallow sub-seafloor precipitation processes, and structural control by faulting is commonly evident. Apart from the famous but anomalous Red Sea metallic oozes and several NE Pacific sites (Middle Valley, Escanaba Trough, Guaymas Basin), however, modern analogs of the sediment-hosted polymetallic sulfide category are lacking. Some deposits hosted by volcaniclastic rocks, such as JADE (Okinawa Trough) and Suzette (Eastern Manus Basin) are strictly sediment-hosted, but their formation is associated with the igneous activity and they are better considered a variant of the more abundant volcanic-associated polymetallic sulfide deposits.

Aug 24, 2006

By Tao Chunhui

The seabed deposits type and distribution are very complex at the hydrothermal field. In this paper, we provided an approach to study the seabed deposits classification at the Precious Stone Mountain hydrothermal field (PSMHF) using MultiBeam sonar data . The PSMHF was found in the Galapogas microplate at the Leg 3 of the Chinese COMRA 21st Cruise. Using this approach, the seabed deposits at the PSMHF are mainly classified into three types, which are rock, breccia and sediment, respectively. We can find the distribution of the three types of seabed deposits according to the sonar backscatter data. The rocks are mostly distributed around the hydrothermal vent. The breccia are located at the foot of the vent. Most sediments are distributed at the southwest to the vent due to bottom current. Combining with seabed video, TV-Grab sample and the backscatter data, we draw the map of the seabed deposits distribution at the PSMHF.

Sep 14, 2011