Search Documents

By William C. Hirt

Column flotation is a promising technique for processing as-mined, cobalt-rich, ferromanganese crust to separate the valuable crust component from barren substrate-rock, either aboard ship or within the water column. Column flotation testing was carried out in a seawater medium using samples obtained from the U.S. Exclusive Economic Zone (EEZ) in the mid-Pacific Ocean near Johnston Atoll. The collector reagent was a mixture of diesel fuel, fatty acid, and sulfonate previously developed at the U.S. Bureau of Mines for crust flotation using conventional flotation cells. Results are dependent upon particle size and reagent dosage, especially *as these factors affect froth volume and stability. Column flotation results are compared with previous studies in conventional cells. An overview of how column flotation might be applied in an offshore mining and processing system is given.

Jan 1, 1992

By Pierre-Yves Morvan

One of the numerous challenge for underwater mining is the positioning. This paper describes an architecture for the integration of an Ultra Short BaseLine (USBL), an Acoustic Synthetic BaseLine (ASBL) operating in Sparse Array mode and a Doppler Velocity Log (DVL) closely coupled with an Inertial Navigation System (INS) for precise subsea positioning in severe environments. By using such architectures, the INS can help to reduce the noise on the measurements coming from acoustic sensors. Another advantage is the capability to reduce the number of required transponders on the seabed, and as a consequence, reduce the time for the deployment and calibration of each transponder. The paper further describes sea-trials performed to assess the ability of a complete positioning system to provide decimetric positioning precision even with a single beacon deployed in the navigation area.

Jan 1, 2017

By Georgy Cherkashov, Vladislav Kuznetsov

The presentation describes new data concerning the age of the Mid-Atlantic Ridge (MAR) hydrothermal fields. The collection of massive sulfides recovered from six hydrothermal fields has been dated using the 230Th/U method. The range of the data obtained is rather wide: from 2.2 up to 65.1 thousand years BP. Three stages of hydrothermal activity were detected for this 65 Kyr period of geological evolution: modern (0 -5), 20-25 and 58–65 thousand BP (Figure 1). This conclusion was confirmed by dating the associated metalliferous sediment layers which also indicate the hydrothermal events led to the formation of sulfide mineralization. There is a correlation between the age and size of massive sulfide deposits: older deposits are larger (Table 1). This and other applications of obtained data will be discussed in presentation.

Aug 24, 2006

By Naoki Hiroyoshi, Kunihiro Hori, Kengo Sekimura, Mayumi Ito, Kouki Kashiwaya, Eiji Yamaguchi, Masami Tsunekawa

Cobalt-rich ferromanganese crusts and nodules ores from seamount areas contain volcanic and sedimentary rocks as substrate or nuclei. During the mining operation, these rocks should be separated as unfavorable waste rocks with the manganese minerals. The ferromanganese crust and nodule ores require mineral processing to remove the substrate rock before the smelting. Deep-sea manganese nodule ores in contrast contain vanishingly small rocks, and can be directly treated with a smelting process without mineral processing treatment. This paper shows phisical and chemical description of the ores for the purpose of mineral processing, and reports liberation degree measurements of crushed ores and gravity separation tests. A mineral processing treatment flow is proposed from the obtained results. There is the first report of applying gravity separation in the treatment of coarse sized crushed products of cobalt-rich ferromanganese crust and nodules ore.

By Daniel E. Walsh

The recovery of most minerals, which are amenable to gravity concentration, is standardly determined by accurate sampling and assaying. .With respect to particulate - gold ores, sampling and assaying are still the convention, but the accuracy and reproducibility of these operations are much discussed and debated points. Evaluation of gravity concentrators by conventional sampling and assaying techniques is very time consuming, costly and may introduce a large amount of uncertainty into the results due to the particulate nature of placer gold. These problems are not unique to placer gold ores and apply to any low grade ore with particulate values. A gravity concentrator evaluation process developed by MIRL employs the use of neutron activated gold (198Au) and radiation detection circuits which monitor the concentrator's product pulp streams. Concentrator recovery is determined from the ratio of the number of gold particles detected as passing into the concentrate to the total number of gold particles detected over all monitored pulp streams. This system eliminates the experimental errors introduced by sampling, sample reduction, and assaying and allows recovery to be evaluated for gold particles of specific sizes, shapes, and flatness. This system enjoys its greatest utility where a large number of tests are to be run in order to evaluate a concentrator over a variety of operational settings, i.e. factorial designs, and allows accurate testing of concentrators operated in closed circuit systems. Beginning in 1984, MIRL conducted radiotracer studies of unit processes, which included jigging, static wedge wire screening, elutriation, and concentration with compound water cyclones.

Jan 1, 1989

By G. Cherkashov

The geodiversity of seafloor massive sulfides (SMS) deposits at the slow- and ultra-slow spreading ridges is of great variety (Fouquet et al., 2010). Tectonics and magmatism are the two principal factors which control SMS formation and localization. The geological setting of SMS deposits is determined by their position relative to the rift valley and by the types of rocks hosted (Table 1). Depending on the first parameter, SMS deposits could be localized at [ ] the axial volcanic ridge or at the flank of the rift valley. Basalts, deep-seated gabbro, and serpentinized peridotites are distinguished among the hosted rocks. The outcrops of deep-seated rocks are exposed at the flanks of the rift valley. The tectonic mechanism of the lower crust and mantle rocks exhumation process is connected with very large offsets along the detachment faults, resulting in a forming oceanic core complex (OCC) (Smith et al., 2006; MacLeod et al., 2009). The SMS related to OCCs are represented by such ore clusters as Ashadze, Logatchev, Semyenov, and some others (Table 1) and are increasing steadily in number. This fact in combination with widespread OCC formation at the slow-spreading ridges (Escartin et al., 2008) and high grades of metals in SMS related to OCCs has provoked considerable scientific and economic interest in these types of deposits. It could be mentioned in this regard that the first two applications to the International Seabed Authority for prospecting and exploration of sulfides have been submitted for the areas in the spreading centres with wide distribution of the core complexes.

Jan 1, 2011

By Jerry Hanua Naime

Papua New Guinea has permitted its first underwater mine. Nautilus Minerals (PNG) Limited is the company permitted to operate the Solwara 1 project. The project is located 30km off the nearest island of New Ireland in the Bismarck Sea. The successful permitting of the activity was due to the existence of a broad legislative framework and the collaborative efforts of stakeholders. Challenges faced included the lack of specific guidelines or policies for underwater mining; lack of existing technology and/or mining method; lack of benefit sharing mechanism for such a project and management of the perceptions of local communities that fear environmental degradation by the mining project. This presentation shares the experience of Papua New Guinea?s first under water mine. A background of the country, the project and the legislative framework are presented. Followed by the challenges and approach taken to permit the project.

Jan 1, 2010

By Derek V. Ellis

A stepwise implementation of seven criteria for screening the physical, chemical and environmental suitability of submarine tailing disposal (STD) at coastal mines is presented. It is expected that similar criteria would be relevant to future deepwater mining. A reconnaissance level study of four preliminary criteria: mine location; coastal bathymetry; feasible outfall locations; and potential for chemical contamination can support or eliminate the prospects for STD. If supportive, detailed, and far more time-consuming hence costly surveys of: environmental background information including oceanography and waste discharge characteristics; projected impacts on other resource uses plus regulatory and community concerns will be essential for environmental protection and to secure the necessary approvals. This review of STD systems on which the proposed screening criteria were based was undertaken by a Cooperative Agreement of the U.S. Bureau of Mines, Alaska Field Operations Center with the University of British Columbia.

Jan 1, 1994

By Winston Rocher Anda

Traditionally, mining activities have been developed in firm land, but technological advances and human needs have opened in the last year?s new opportunities in the maritime field. This has happened not only in the oil or hydrocarbons industries, but also in relation to the exploration or exploitation of other minerals, metallic and non-metallic. This has forced several countries to complement or create legal rules that make possible its own development and the International Law, through the United Nations Convention on the Law of the Sea, to regulate this activity in the space of its own, the calling area. Chile, as country with a long experience in mining and great advances in large deposits exploitation, possesses a special juridical frame that regulates this economic activity according if it is the geographical or territorial area in which is realizes, and it has been complemented lately with the international normative.

Jan 1, 2011

By R. Moss

Gold and silver are important byproducts of mining volcanogenic massive sulfide (VMS) deposits. Both metals occur in VMS deposits ranging in age from the Archean to the currently forming massive sulfides found on the ocean floor. The gold- and silver-rich deposits on the modern seafloor are geographically diverse and occur in several different tectonic settings (Figure 1a,b) including seamounts (e.g. Franklin Seamount, Papua New Guinea), unsedimented mid ocean ridges (e.g. TAG and Snakepit, Mid Atlantic Ridge), sedimented mid ocean ridges (e.g. Escanaba Trough) and back-arc basins (e.g. Manus Basin, Papua New Guinea). Interestingly, the most gold- and silver-rich deposits are found in the back-arc basins of the western Pacific, commonly associated with differentiated volcanic rocks such as the dacite-rhyodacite suite at PACMANUS in the eastern Manus Basin. This suggests that different, or more efficient, mechanisms are concentrating precious metals in such back-arc settings. Such mechanisms may include leaching of volcanics enriched in gold (e.g. rifted arc crust) or silver (e.g. continental crust) and/or the introduction of gold into a hydrothermal system by a magmatic fluid. The gold content of modern seafloor precipitates varies from a few ppb up to a high of 54 ppm reported from eastern Manus Basin (1). The Jade Deposit in the Okinawa Trough has the highest silver contents with values up to 1.1% (2). Both gold and silver are preferentially concentrated in late-stage, low temperature precipitates with zinc-rich assemblages being favoured in most cases. Gold is found as relatively pure native gold and sub-microscopic inclusions in gold-rich deposits, but occurs predominantly as sub-microscopic inclusions and possibly as solid solution in the gold-poor deposits (3). Silver occurs as rare silver minerals such as acanthite and native silver in the silver rich Jade deposit (2), but more commonly in the silver-containing minerals tetrahedrite and tennantite, as is the case in the PACMANUS deposit. Tetrahedrite is also known to be an important host of silver in ancient VMS deposits (4). More abundant sulfides can contribute significantly to the silver balance. In the silver-poor deposits at 21 N East Pacific Rise, silver is contained entirely within chalcopyrite, isocubanite, pyrite, marcasite, sphalerite/wurtzite and galena. In this case silver may be present as sub-microscopic inclusions of silver minerals or in solid solution.

Jan 1, 2011

By C. R. Pearce, B. Murton, S. Howarth, P. Lusty

"With the expansion of “green” energy technologies, the demand for the critical raw materials required to sustain this growth is increasing. Many E-tech elements, including tellurium (Te) and rare earth elements (REEs), suffer from high supply shortage risk and the need for more diversified metal supply routes is driving research into alternative resources. Hydrogenetic ferromanganese crusts, seafloor deposits of Fe- and Mnoxyhydroxides that form from the direct precipitation from seawater, present a potentially important future source of E-tech elements. With growing interest in the potential wealth of these deposits and the issuing of permits for deep-sea mining and exploration, more work is underway to understand the nature of ferromanganese crust deposits, their elemental concentrations and distributions, and the potential impacts of mining activities.This research focusses on the formation of ferromanganese crust deposits and processes that control the extreme enrichment of elements such as Te, Co and REEs. The crusts were systematically sampled and mapped between ~ 1000 – 4000 m depths using ROV ISIS, from a range of environments, substrates and morphologies from Tropic Seamount (NE Atlantic) in order to determine the seamount-scale factors that control major and trace elemental concentration variations. These factors include depth, surface roughness and micro-bathymetry, location relative to long-term mean current direction and energy, influence of tidal energy dispersion across the seamount, sediment supply, substrate lithology, biological productivity and phosphatisation. The study analyses trace-element characteristics of 100 ferromanganese crust samples alongside standard reference materials NOD-A-1 and NOD-P-1 (US Geological Survey manganese nodules). At this initial stage, we report results from whole rock acid digestion and ICP-MS analyses."

Jan 1, 2017

By James R. Herring

An unusual combination of ten new, deep (-100 m) coreholes and an extensive high-resolution seismic reflection network enables us to produce a detailed study of the phosphorite resources in the Tertiary strata of the Georgia continental shelf. These strata are mixtures of a terrigenous facies, notably quartz and clay along with minor amounts of other aluminosilicate minerals, and of a marine facies, notably phosphorite and carbonate. Phosphatic sediments occur throughout the cores, however the richest phosphorite beds are in the middle Miocene (Serravallian) sediment, where they constitute up to 70 percent of the sediment mass. Major zones of phosphate enrichment occur chiefly at major unconformity boundaries (tops of Oligocene, lower and middle Miocene, upper Miocene, and lower and upper Pliocene) and at prominent intrastratal reflectors representing minor unconformities within units. Phosphorite co-occurs with the clay minerals, especially palygorskite, but correlates inversely with carbonate and detrital quartz, indicating a low-energy depositional environment. The clay minerals present in these strata, which have an environmental consequence on recovery of the phosphorite, are varying concentrations of smectite, kaolinite, mica, palygorskite, and sepiolite. Phosphatic resources have been determined within only the Miocene strata. Sediment volume for this unit to the 100 m isobath on the continental shelf has been established using the high-resolution seismic reflection network that has been calibrated using the deep coreholes. Phosphorite grains larger than 0.1 mm average about 40% of the sediment. In turn, most of the remainder of the sediment in this size range is quartz, which is separable from phosphate grains using conventional flotation techniques. Our estimate is that 300 Gt of phosphorite lie within the Miocene strata of the Georgia continental shelf.

Jan 1, 1994

By William Siapno

Manganese nodules, as metal ores, have for the most part been cast aside from further consideration within this century. However, in the decade of the 90s, rising demand at all levels of society, for clean air give nodules a new - lease on life as a stack gas cleaning agent. Further, the Clean Air act of 1990, mandates enormous outlays to bring systems into compliance with new stringent standards. Quick corrective actions are imperative. Research beginning in the 1960s proved nodules possess unique qualities to remove acid compounds from stack gases. Early this year, the National Science Foundation awarded General Electric an $83 million contract to design a system to extract oxides of sulfur and nitrogen from coal fired power plants. Environmental damage is abundantly evident on the ground, from the air as well as form space. A dirty pall of yellow-brown smog is smothering both animal as well as plant life around the globe. Losses run into billions!

Jan 1, 1991

By Kiseong Hyeong

The Intertropical Convergence Zone (ITCZ), where the southeast and northeast trade winds converge, is the effective climatological barrier that separates the southern and northern hemispheres in terms of dust budget. Asian and N. American dusts dominate in the Pacific north of the ITCZ, while Central and S. American dust prevails south of the ITCZ. In order to understand the nature of latitudinal and depth-related variations of mineral composition in terms of position relative to the ITCZ, deep-sea core sediments were collected from 9°N to 17°N at a 2° intervals along the 131.5°W meridian and analyzed for mineral composition. The amount of illite in surface sediments decreases gradually from 65% at 17°N to 31% at 9°N. In contrast, smectite increases from 11% to 56% southward. The observed mineralogical variation toward the ITCZ is attributed to the increased supply of volcaniclastic material transported via the southeast trade winds from the Central and South America source regions. Smectite-illite transition, a phenomenon that the amount of smectite increases over illite, occurs at around 10°N, the northern margin of the ITCZ. This result indicates that the change in latitudinal position of the ITCZ in the geological past could be recorded by the smectite-illite transition in deep-sea cores. The cores studied show down-core variation of mineral composition from illite-rich at the surface to a smectite-rich clay suit at depths, similar to the latitudinal variation. The smectite-illite transitions observed in these cores are likely the records of changes in latitudinal position of the ITCZ. The depth and age of the smectite-illite transition is getting shallower and younger towards the equator, implying that the ITCZ was located farther north during late Tertiary and has shifted southward to the present position of 5°N~10°N.

Jan 1, 2004

By Carl H. Hobbs

The needs of the on-going basic maintenance operations and proposed enhancement and hurricane protection projects in the City of Virginia Beach exceed the capability land-slide sources of sand. Through the past several years our studies have concentrated on locating and defining suitable quantities of sand appropriate for use on the area's beaches and assessing some of the consequences of dredging in shallow offshore areas. By providing information concerning the geological setting of sand resources, the local wave climate, and benthic infauna, the overall research project has strengthened the knowledge and understanding of several facets of Virginia's inner continental shelf. We have identified three distinct settings for deposits of beach-quality sand, two of which (filled channels and surficial shoals) are distinguishable in relatively unprocessed sub-bottom profiles and cores. The third, a sand facies within a larger stratum, is discernable only with a suite of cores. Sandbridge Shoal, about 5 km offshore of the resort and residential community of Sandbridge appears to contain a substantial quantity of sand that could be exploited with comparatively few problems. It already is designated as the source of material for use in a shoreline protection protect for a federal facility. Fluvial(?) fill of a late Pleistocene channel lust offshore of the main, commercial, resort area may offer a proximal alternative to existing and proposed resources. Ongoing work to describe the local wave climate and the possible impacts of anthropogenic alterations of the bottom topography on wave transformation and studies of the biological community as it might be affected by dredging will help fill-out our series of studies. Prior to utilization of the resource additional work is needed to provide better definition of the limits and magnitude of the sand bodies. Finally decisions concerning the use of specific resources will have to include physical, biological, economic, technical, and social considerations.

Jan 1, 1996

By Kira Mizell, James R. Hein

Ferromanganese (FeMn) crusts form by precipitation of iron and manganese oxides from seawater onto a rock substrate and are therefore considered hydrogenetic in origin. Diagenesis does occur however, through the process of phosphatization. During phosphatization, abundant dissolved phosphate in seawater replaces carbonate in the detrital fraction as well as directly precipitates within the FeMn matrix as carbonate fluorapatite (CFA). This process is likely accompanied by the partial dissolution or replacement of the oxide phases [1]. As a result of these diagenetic processes, trace elements adsorbed on the oxides are released and can either be depleted or enriched in the phosphatized FeMn crust layers. Pb, for example, has been shown in sequential leaching experiments to associate with the iron oxyhydroxide (FeOOH) phase in purely hydrogenetic layers, while >95% of Pb in phosphatized crust layers is found in the CFA fraction [2, 3]. However, previous sequential leaching studies analyzed bulk layers of phosphatized crusts and only a few crusts, from the Pacific Ocean. Here we present concentration data for Pb and other trace elements in the CFA fraction leached from thin stratigraphic intervals of the phosphatized portion of FeMn crusts from the Pacific and Atlantic oceans to confirm consistency of trace metal association with CFA both throughout the phosphatized section and in two ocean basins. The Pb and trace element concentration data from this study will also be compared with data from non-phosphatized crusts from the global ocean. We can then determine the effect of phosphatization on the concentration of Pb and other elements of greater economic interest in FeMn crusts, specifically whether there is overall enrichment, depletion, or possibly even phase transfer of each metal in the phosphatized layers.

Jan 1, 2018

By Janine Lahr, Peter E. Halbach

The Manus Spreading Ridge is located within the EEZ of Papua New Guinea and lies in the Manus Basin ENE of the PNG Island and N of the Island New Britain. The divergent backarc spreading system is caused by the subduction of the Solomon plate in the South under the Bismarck plate in the North along the lineament of the New Britain trench. The rate of divergence is relatively high compared to other back arc spreading systems and amounts up to 12 cm/year [3]. Since submarine volcanism and associated hydrothermal circulation as important parts of the oceanic heat transfer system are also dependent on the rate of spreading, hydrothermal fluid venting and respective deposition of polymetallic sulfides can be expected there. In late 1985 first indications for hydrothermal activity were observed on a swell within the central rift valley of the Manus Spreading Centre during a photographic survey of the seafloor by an expedition of the Hawaii Institute of Geophysics with the American RV Moana Wave [1]. Detailed geological investigations including successful sampling were first carried out in June 1990 within the scope of the OLGA II research project (conducted by Prof. Tufar, Marburg) using the German RV Sonne equipped with a deep-sea television sledge and Tvcontrolled grab systems. Simultaneously a research cruise with the Russian RV Akademic Mstivlav Keldysh took place using the manned submersible Mir; the findings of the OLGA II cruise were immediately used for planning and organization of the Mir dives [3]. The massive sulphide samples which we used for our geochemical and mineralogical studies originate from the hydrothermal fields 1 and 2 and are from grab stations of the OLGA II expedition [4].

Sep 24, 2006

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 R. K. H. Falconer, Wood R. A., C. D. Castle

"A deposit of phosphate nodules is on the Chatham Rise approximately 450 kilometres to the east of Christchurch in the South Island of New Zealand. The deposit contains sufficient rock phosphate to supply New Zealand’s phosphate fertilizer needs for at least 20 years. It was first investigated commercially 50 years ago by Global Marine, followed by JBL Minerals in the early 1970’s. NZ and German government research and industry groups then took it up again, with major field programs in 1978 and in the early 1980s.Due to difficult global and local economic conditions the project ground to a halt in 2004.The project was resurrected in 2007 when Chatham Rock Phosphate applied for a prospecting licence. This was granted in 2010 and a successful subsequent mining permit approval followed in 2013. The initial application for the separately required environmental permit was declined in February 2015.A lot has changed then and the significance of this will be the subject of the presentation. Chatham Rock Phosphate is confident that an environmental permit will be successfully granted next time."

Jan 1, 2017

By Dallas L. Peck

The U.S. Geological Survey (USGS) recently completed phase 1 of a mapping effort that makes the United States the first nation to systematically acquire image maps of its underwater lands. In 1984, the USGS, as part of its mission to map and characterize the resources of the Federal lands, began a mapping effort in the newly proclaimed Exclusive Economic Zone (EEZ). The goal was to provide sonar image maps of this frontier area within 10 years. The mapping program is on schedule, with two-thirds of the EEZ sea floor, approximately 2 million square nautical miles, happed in 7 years. The deep water EEZ (depth greater than 200 m) around the 50 states is now complete except for the North Slope of Alaska, where ice precludes our surveying with a surface ship. Phase 2 of the EEZ mapping effort will begin in 1994, focusing on the American Flag islands of the western Pacific. Approximately 1 million square nautical miles of sea floor remain to be mapped around the islands.

Jan 1, 1992