Cobalt-rich Crusts Research Articles

Determination of halogen levels in marine geological samples

ABSTRACTA method for determining levels of fluorine (F), chlorine (Cl), bromine (Br), and iodine (I) in marine geological samples using wavelength dispersive X-ray fluorescence is presented here. Samples are prepared as pressed powder pellets. The method makes full use of the advantages of the ability of the modern X-ray fluorescence spectrometer to detect ultra-light elements and high-powered X-rays. A series of calibration standards with an appropriate concentration range was developed using a standard addition method. Empirical coefficients were used to correct for matrix effects in the case of F and Cl, the rhodium Kα -Compton peak was used as internal standard for Br matrix corrections, and the rhodium Kb-Compton peak was used to correct for the matrix effect on I. For % concentration of the analyte, the precision (relative standard deviation) of the method was <5%. For concentrations <0.1%, the relative standard deviation depended heavily on the count rates (or concentration). The accuracy of the method was validated by comparison of the results to similar reference materials. The detection levels of this method (counting time100 s) were 100, 5, 0.5, and 10 µg g−1 for F, Cl, Br, and I, respectively. The method was here used to determine the levels of halogens in samples of 19 marine sediments (China, Russia, Canada, American), 10 marine manganese nodules (China, Russia, American, Germany, India, Japan), 4 cobalt-rich crust reference materials (Russia, China), reference materials, and 3 phosphorites.

Variations of calcareous nannofossils of cobalt-rich crusts and geological records at the Eocene-Oligocene transition in western Pacific seamounts

Two records of the crust laminae from the Marcus-Wake Seamounts and the Magellan Seamount were biostratigraphically studied. Based on biological imprints of the calcareous nannofossils, the geological ages of the two records were determined, with CM1D03 from the Marcus-Wake Seamounts being of late Paleocene to Pleistocene and CM3D06 from the Magellan Seamount of Late Cretaceous (more than 70.0 Ma). There are the obvious temporal-spatial differences in the initial formation period and enrichment characteristics of the cobalt-rich crusts of the two seamount chains and differences in the combination and distribution of microfossils in the inner crust layers between the seamounts. These differences are due to the adaptabilities of oceanic species in different environments. Ecological research was carried out in terms of population size of the calcareous nannofossils preserved in the crustal layers to discern the relation of the geological events at the Eocene-Oligocene (E/O) transition. The results show the transitions and recombination of species in the biotic community during the E/O transition obviously corresponded to 25 mm depth in the CM1D03 crust and 58 mm depth in the CM3D06 crust. The changes in biological species and the formation of particular ecological structures indicate the adaptive response of the paleo-biological community in the western Pacific Ocean to the global cold-climate events and the close correlation between the formation of the crust and the global climate change.

Environmental Issues of Deep-Sea Mining

As terrestrial mineral deposits are either depleting or of low grade, minerals from the deep-sea like the polymetallic nodules, cobalt rich crusts and polymetallicsulfides are considered as alternative sources for metals such as Cu, Ni, Co, Mn, Fe, that could be exploited in future by developing suitable technologies for mining as well as extracting metals from them. As most of these deposits occur in the international waters, several ‘contractors’ have staked claims over large tracts of the seafloor in the international waters under the UN Law of the Sea. Simulated seafloor mining experiments have revealed significant information on the potential impacts that may occur as also several measures for conserving the environment have been suggested.

コバルトリッチクラストからの金属回収技術の現状と課題

The cobalt rich manganese crusts are distributed on the flat top or the slope of seamounts in the economic zone and the open sea around Minami Torishima Island. Cobalt rich manganese crust and manganese nodule are iron manganese oxide mainly composed of oxide of Mn and Fe. However, their distribution condition and composition are different. Manganese nodule contains some 2.0% of copper and nickel together. On the other hand, the cobalt rich manganese crust includes less copper and nickel than manganese nodule does, but contains a higher level of cobalt and platinum. Metal Mining Agency of Japan (MMAJ), which is current Japan Oil, Gas and Metals National Corporation (JOGMEC), has selected“ Smelting and Chlorine Leaching” as the most suitable technique from the viewpoint of nickel, cobalt and copper's recovery from the manganese nodule. (Kojima, in 1996) For the treatment of cobalt rich crust, JOGMEC has established an improved metal recovery technology, which is called the“ Improved Smelting and Chlorine Leaching”, after the investigation from 2003 through 2008. . In the“ Improved Smelting and Chlorine Leaching”, JOGMEC has introduced“ slag cleaning” process for cobalt and another process for platinum in order to enhance the recovery level. Also JOGMEC found technique to recover metal using bioleaching effectively.

Microrhythmic distribution of Co, Mn, Ni, and La contents in cobalt-rich ferromanganese crusts from the Magellan Seamounts

Variations in the contents of Fe and Mn and a number of trace elements (Co, Ni, Cu, Zn, As, Rb, Sr, Y, Zr, Pb, Th, U, Te, Ba, La, Ce, Nb, and Mo) were simultaneously measured in microlayers in samples of cobalt-rich ferromanganese crusts from the surface of three guyots of the Magellan Seamounts by means of synchrotron micro-XRF analysis on a VEPP-3 accelerator facility at the Institute of Nuclear Physics of the Siberian Branch of the Russian Academy of Sciences. Micro-scale periodic variations were detected in the contents of most trace elements. The high and low contents of Co, Ni, and Mo in the crusts display also a larger scale periodicity.

Biomineralization of organic matter in cobalt-rich crusts from the Marcus-Wake Seamounts of the western Pacific Ocean

Organic matter in cobalt-rich crust (CRC) from the Marcus-Wake Seamounts of the western Pacific Ocean, Sample CM1D03, has been analyzed to understand the source, geochemistry and mineralization of organic matter, and the mineralization environment. Biomarkers, including n-alkanes, isoprenoids, terpanes and sterols, have been detected in various layers of the CRC sample, using gas chromatography (GC) and gas chromatography-mass spectrometry (GC-MS). The content of organic carbon (OC) and its stable isotope (δ13C), and the combined features of the biomarkers show that the mineralized organic matter in CM1D03 CRC was mainly derived from microorganisms and lower plankton (e.g., bacteria and algae, respectively) from marine surface water, with some terrestrial higher plant components. The ratio of chloroform bitumen “A”: OC was high in the CRC, between 10.51 and 20.66, showing significant migration characteristics of n-alkanes. Four mineralization categories of organic matter were recognized based on GC chromatograms of n-alkane molecules: (1) primitive type (bacteria and algae), which is characterized by moderately mature of n-alkanes preserving the original characteristics of the organic matter from microorganisms and lower plankton; (2) microbial degradation type, which is characterized by low contents of n-alkanes and rising baseline in the chromatogram, with the “bulge” being the products of organic matter by biodegradation; (3) organic matter migration type, which is characterized by low carbon number of n-alkanes with nC18 as the main peak carbon, without odd even predominance, and low concentrations of isoprenoids and hydrocarbons with high carbon number; and (4) organic matter hydrothermal type, which is characterized by relatively low concentration of small molecular weight n-alkanes, pristane, and phytane, accompanied by higher concentration of n-alkanes with carbon number greater than nC18. This study shows that biomarkers can record controlling factors of mineralization and their variation.

High-Speed Photogrammetry Application for Percussive Rotary Cutting Tests of Deep-Ocean Cobalt-Rich Crusts

The cutting processes of drill rod under different surge pressures, rotate pressures and propulsion forces were recorded by the high-speed camera in the hydraulic percussive rotary cutting tests of deep-ocean cobalt-rich crusts. Meanwhile, the curves of impact vibration, torsional vibration and frame vibration during the cutting processes were plotted by digital picture processing technique. The impact frequency, torsional vibration frequency, torsional vibration amplitude, vibration amplitude of drill rod and the frame were calculated. The photogrammetry results are generally in agreement with the traditional test results. High-speed photogrammetry is a non-contact, wide range application, and high precision measurement, and the cutting process can be described visually and adequately.

Regional Distribution of Co-Rich Ferromanganese Crusts and Evolution of the Seamounts in the Northwestern Pacific

Cobalt-rich hydrogenetic ferromanganese crusts in the Pacific seamounts are potential mineral resources for Co, Ni, Pt and REEs. The Northwest (NW) Pacific, in particular, is one of the most promising areas for the ferromanganese crusts. During the six cruises of the Japanese research vessel Hakurei Maru No.2 over the seamounts of the Marshall Islands in 1996, 1998 and 2002, and the Federated States of Micronesia (FSM) in 1997, 1998 and 2005, the patterns of distribution, resource potential and the relationship to geological parameters were found to be characterized by the potentiality for the ferromanganese crusts. In this article, the relationship between crust abundance and diversity in the geological evolution of the seamounts is discussed on the basis of bathymetric, geological, geophysical and environmental data.

Experimental Study of the Shear Strength of Cobalt-Rich Crusts

The shear strength parameter of cobalt-rich crusts can be used to design cobalt-rich crusts mining head. The shearing test of cobalt-rich crusts sample was done with different angle shearing testing apparatus.Firstly, the cobalt-rich crusts sample with the size of 50mmx50mmx50mm cube was clamped in the variable angle plate.Secondly, the sample ware loaded till to be damaged. Lastly,the damaged load were recorded at the degree of 50, 60 and 70 to establish their shearing strength and normal stress empirical formula.According to the testing result, its cohesion and internal friction angle parameters are respectively 0.275MPa and 54.43 degree. Restricted by the number of samples and limited by laboratory testing,in-situ shearing strength test should be carried out to improve the proposed empirical formula.

Research on the Over-obstacle Capacity of the Deep Sea Composite Wheeled Mining Robot

Due to the complex and varied substrate environmental characteristics of cobalt-rich crusts and hydrothermal sulfide survey area in deep sea,a composite wheeled mining robot with active and passive over-obstacle capacity is designed. The mining robot is composed of 4-composite wheels and an integral articulated sealed compressive tank frame.A static model of the composite wheels structure is set up in the typical over-obstacle condition,to obtain its main structural parameters affecting over-obstacle capacity.Using MATLAB toolbox,the composite wheels structural parameters are optimized for design,so that the over-obstacle capacity is improved.Considering the complex and varied substrate environmental characteristics in deep sea,dynamics model of the optimized composite wheeled robot is set up,the simulation analysis with ADAMS is performed,and dynamic characteristics curve and mechanical characteristics curve of the mining robot are obtained in over-obstacle process.Through designing prototype and testing its over-obstacle capacity,it is shown that the mining robot has strong over-obstacle capacity and transit stability in the complex and varied deep sea substrate environment.

Microbial diversity in deep-sea sediment from the cobalt-rich crust deposit region in the Pacific Ocean

Cobalt-rich crusts are important metallic mineral resources with great economic potential, usually distributed on seamounts located in the Pacific Ocean. Microorganisms are believed to play a role in the formation of crusts as well as in metal cycling. To explore the microbial diversity related to cobalt-rich crusts, 16S ribosomal RNA gene clone libraries were constructed from three consecutive sediment layers. In total, 417 bacterial clones were obtained from three bacterial clone libraries, representing 17 distinct phylogenetic groups. Proteobacteria dominated in the bacterial communities, followed by Acidobacteria and Planctomycetes. Compared with high bacterial diversity, archaea showed a remarkably low diversity, with all 137 clones belonging to marine archaeal group I except one novel euryarchaeotal clone. The microbial communities were potentially involved in sulfur, nitrogen and metal cycling in the area of cobalt-rich crusts. Sulfur oxidation and metal oxidation were potentially major sources of energy for this ecosystem. This is the first reported investigation of microbial diversity in sediments associated with cobalt-rich crusts, and it casts fresh light on the microbial ecology of these important ecosystems.

CUTTER CUTTING COBALT-RICH CRUSTS WITH WATER JET

Cobalt-rich crusts cutting method of cutter with water jet is proposed to reduce cutter impact load. Finite element model of cutter cutting cobalt-rich crusts with water jet was established and surface initial crack forming conditions of cobalt-rich crusts were simulated. Simulation results show when water jet pressure is less than compressive strength of cobalt-rich crusts and water jet action point is not overlap with cutter action point, water jet can't reduce the minimum cutting force of cutter, which is used to form initial crack. When water jet action point is overlap with cutter action point, water jet can reduce the minimum cutting force effectively. When water jet pressure is greater than cobalt-rich crusts compressive strength, water jet can generate initial crack on cobalt-rich crusts surface alone. Experiments of cutter cutting cobalt-rich crusts simulation material with water jet were carried out. Experimental results show when water jet action point is not overlap with cutter action point, water jet can't reduce the maximum impact load of cutter, but it can reduce the root mean square of impact load. When water jet action point is overlap with cutter action point, water jet can reduce the maximum impact load dramatic and the root mean square of impact load is decreased accordingly. http://dx.doi.org/10.5755/j01.mech.17.4.580

Distribution characteristics of seamount cobalt-rich ferromanganese crusts and the determination of the size of areas for exploration and exploitation

In 2001, the International Seabed Authority (ISBA) initiated the consideration relating to the Regulations for Prospecting and Exploration for Hydrothermal Polymetallic Sulphides and Cobalt-rich Ferromanganese Crusts in the Area at its 7th session. Since then, the consideration of the Regulations has been mainly focused on the size of areas to be allocated for exploration and exploitation of the crusts. This paper, based on the investigation data and the analysis of the distribution characteristics of the crusts, suggests a model for determining the size of areas for exploration and exploitation of the crusts, taking into account various factors such as production scale, crust thickness and grade, mineable area proportion, recovery efficiency, exploration venture, and so on. Through the modeling, the paper suggests that the exploration area (the area covered by each application for approval of a plan of work for exploration of cobalt-rich crusts) shall be 4 856 km2 and the exploitation area (the mine site area) shall be 1 214 km2, for 20 years of 1 million wet tonnes annual production.

Geophysical and Geological Exploration of Cobalt-rich Ferromanganese Crusts: An Attempt of Small-Scale Mapping on a Micronesian Seamount

Ferromanganese crusts in the Pacific Ocean are potential economic resources of cobalt, nickel and platinum. Previous shipboard geological and geophysical exploration has been directed towards innovation in effective methods of mapping the abundance and grade of manganese nodules on the seafloor for evaluation and mine site selection. However, any simple techniques have not been valid for complicated and variable nature of the crusts and topography. This study attempts to establish a distribution pattern of ferromanganese deposits on a Micronesian seamount using conventional narrow-beam and SSS mapping, dredge sampling Cand TV/camera monitoring with a geological interpretation. We tried to correlate acoustic remote sensing data with the surface geology, and decipher the regional-scale distribution of crusts in relation to large-scale mass wasting that took place in the early Miocene or before. The general distribution pattern of crusts over the surface of the seamount indicates that only about 40% of the apparent “acoustic outcrop” represents actual ferromanganese crust coverage. The combined method outlined here is the most useful in evaluating ferromanganese deposits, prior to possible hi-tech fine-scale mapping using submersibles, ROV and AUV.

Platinum Recovery from Hydrochloric Acid Leaching Solution of Cobalt-Rich Crust by Seaweed Biosorption and Activated Carbon

In order to recover trace of platinum (Pt) from hydrochloric acid (HCl) leaching solution of Cobalt-Rich Crust (CRC), the absorption properties of four kinds of seaweeds (Undaria pinnatifida, Laminaria angustata, Enteromorpha linza and Gloiopeltis tenax) and activated carbon were studied. At first, their adsorption abilities for Pt ion as well as selective adsorption properties for other coexisting metal ions contained in CRC (including iron (Fe), manganese (Mn), cobalt (Co), nickel (Ni) and copper (Cu)) were investigated by using artificial solutions. Finally, the application to CRC HCl leaching solution was also carried out. The results showed that all seaweeds achieved their best Pt adsorption capacity only at pH 2, whereas activated carbon possessed a high Pt adsorption ability over a wide pH range from pH 0 to 6 as well as in HCl solution up to 3 mol/L. Regarding the CRC leaching solution obtained by 0.5 mol/L HCl and 1 vol.% hydrogen peroxide (H2O2), 46.9% and 100% Pt was recovered by Enteromorpha linza and activated carbon, respectively. It was found that seaweed and activated carbon are both effective adsorbents for recovering Pt from HCl leaching solution of CRC.

Marine biominerals: perspectives and challenges for polymetallic nodules and crusts

Deep sea minerals in polymetallic nodules, crusts and hydrothermal vents are not only formed by mineralization but also by biologically driven processes involving microorganisms (biomineralization). Within the nodules, free-living and biofilm-forming bacteria provide the matrix for manganese deposition, and in cobalt-rich crusts, coccolithophores represent the dominant organisms that act as bio-seeds for an initial manganese deposition. These (bio)minerals are economically important: manganese is an important alloying component and cobalt forms part of special steels in addition to being used, along with other rare metals, in plasma screens, hard-disk magnets and hybrid car motors. Recent progress in our understanding of the participation of the organic matrices in the enrichment of these metals might provide the basis for feasibility studies of biotechnological applications.

Geochemistry of rare earth elements in cobalt-rich crusts from the Mid-Pacific M seamount

Rare earth elements (REEs) and major elements of 25 cobalt-rich crusts obtained from different depths of Mid-Pacific M seamount were analyzed using inductively coupled plasma-atomic emission spectrometer and gravimetric method. The results showed that they were hydrogenous crusts with average ∑REE content of 2084.69 μg/g and the light REE (LREE)/heavy REE (HREE) ratio of 4.84. The shale-normalized REE patterns showed positive Ce anomalies. The total content of strictly trivalent REEs increased with water depth. The Ce content and LREE/HREE ratios in Fe-Mn crusts above 2000 m were lower than those below 2000 m. The change in REE with water depth could be explained by two processes: adsorptive scavenging by setting matters and behaviors of REE in seawater. However, the Ce abundance took no obvious correlation with water depth reflects the constant Ce flux. The Ce in crusts existed mainly as Ce(IV), implying that the oxidative-enriching process was controlled by kinetic factors.

Fundamental Study on the Electrical Disintegration of Cobalt-Rich-Crust for Platinum Recovery

In order to recover trace of platinum (Pt) from Cobalt-Rich-Crust (CRC), electrical disintegration was carried out to liberate the CRC. Electrical disintegration was performed by introducing high voltage impulse to the CRC, which broke down the CRC along the grain boundaries of minerals with different electrical parameters in it. In this study, the feasibility of liberating CRC by electrical disintegration was investigated, and the Pt grade in the CRC fragments after electrical disintegration was compared with the one after mechanical comminution. The results showed with the increase of the thickness of CRC, the applied voltage for the electric breakdown was also increased. Higher applied voltage made the particle size of CRC fragments smaller. When electrical disintegration was performed in conductive solution, the applied breakdown voltage and electric energy consumption needed was greatly increased since the majority of the current flowed through the solution instead of CRC. However, it could be prevented by using coated discharge electrode, which makes electrical disintegration of CRC perform in seawater possible. The Pt grade in smaller CRC fragments from electrical disintegration and mechanical comminution were almost the same; however, larger CRC fragments possessed higher Pt grade from electrical disintegration than the one from mechanical comminution.

Leaching of Platinum from Cobalt-Rich Crust by Hydrochloric Acid with Hydrogen Peroxide

Leaching of platinum (Pt) traces from Cobalt-Rich Crust (CRC) in hydrochloric acid (HCl) solution with hydrogen peroxide (H2O2) was carried out in this work. Two kinds of CRC samples with different Pt grades were used and the effects of HCl and H2O2 concentration, leaching temperature and time as well as solid-liquid ratio were investigated to evaluate the Pt leaching. The results showed that more than 95% of Pt in the CRC sample was leached out in HCl solution which concentration was more than 2 mol/L. The leaching temperature was higher than 50°C and the time was longer than 30 min whereas the solid-liquid ratio was less than 50 g/L. Similar results were observed when using HCl solution of more than 0.5 mol/L with the addition of more than 1 vol.% H2O2, while the leaching temperature was kept at 30°C and the time was longer than 15 min but at a reduced solid-liquid ratio (i.e. less than 10 g/L). There was no difference on Pt leached fraction between the two CRC samples with different Pt grades.

Element Distribution in Cobalt-Rich Crust Profile by Laser Ablation-Inductively Coupled Plasma-Mass Spectrometry

A method was established for the determination of the element composition and distribution in different layers of cobalt-rich crust profile by 193 nm ArF excimer Laser ablation-inductively coupled plasma-mass spectrometry (LA-ICP-MS). The crust standard reference material (GSMC-1) was used as the external standard and Ti was used as the internal standard element for the quantitative determination of multi-element in different layers of the cobalt-rich crust. The proposed method was applied to the analysis of the crust samples GSMC-2 and GSMC-3; the relative error and relative standard deviation were less than 10%, and the detection limits of the element were in the range of 3.2–191 ng g −1 (with the exception of silicon). The concentration of the ore-forming and rare earth elements in different crust layers of a cobalt-crust sample MDD-42, which was collected from Magellan seamounts in the western Pacific, was determined by LA-ICP-MS. The distribution of elements in different crust layers was investigated in detail. The results indicated that the enrichment and depletion of elements are closely related to the geological process and the paleoceanic environment during their growth period.