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Opportunities Ahead
Published in Ranadhir Mukhopadhyay, Victor J. Loveson, Sridhar D. Iyer, P.K. Sudarsan, Blue Economy of the Indian Ocean, 2020
Ranadhir Mukhopadhyay, Victor J. Loveson, Sridhar D. Iyer, P.K. Sudarsan
Because of ever-growing demand for strategic metals, the focus of the international community has fallen on deep-sea manganese nodules occurring at a water depth of more than 4,500 m. The mining of polymetallic nodules from the seabed remains a tempting, but technologically challenging option. The new ventures involving exploration and mining have greater scope for development and economic contribution to every country. A recent economic appraisal and strategy for mining of nodules from the Indian Ocean Nodule Field—one of the four economically potential areas in the world oceans—suggests that in contrast to an overall perception of non-viability of nodule mining, a fair degree of economic feasibility and commercial sustainability to mine the deep-sea manganese nodules exists in the IOR (Mukhopadhyay et al., 2019). The other deep-sea resources like cobalt crust atop major seamounts, and hydrothermal sulfides from the mid-oceanic ridge system need more research and constrained exploration to identify and assess the extent and richness of mineralized zones.
Leaching with Acids
Published in C. K. Gupta, T. K. Mukherjee, Hydrometallurgy in Extraction Processes, 2019
It has been emphasized in literature and in the first chapter of this book that for assuring the supply of metals and materials for the future, we cannot continue to depend on land-based resources. The ocean beds have shown enough indication of the possibility of vast reservoirs of metals and materials. A great deal of attention has been focused the world over on using manganese nodules from the ocean bed as potentially important and huge mineral resources. Extensive research efforts are being conducted to evolve an economical method of processing the manganese nodules. Among the acid-leaching techniques evaluated so far for the treatment of manganese nodules is the work of a Belgium Company,100 Metallurgie Hoboken-Overpelt (MHO). The process involving leaching with hydrochloric acid has come to be known as the MHO process. The nodules are crushed and leached with concentrated hydrochloric acid to dissolve manganese and other valuable metal oxides. The basic principle and flowsheet of the process have already been described in Chapter 1 with the help of Figures 4 and 5. The dissolution of nodules was claimed to be more or less complete, and the leach liquor contained 110 to 120 Mn, 25 Fe, 5 Cu, 1 Co, 0.6 Zn, 0.3 V, and 0.2 Mo in g/l. The total chloride concentration of the liquor was about 200 g/l. The acid leach liquor was subjected to a series of solvent extraction and precipitation steps to recover pure salts of copper, aluminum, nickel, manganese, zinc, molybdenum, and vanadium. The final solution contained only magnesium chloride and was pyrohydrolyzed in a spray roaster to recover HCl for leaching and magnesia for various neutralization steps.
Mineral Extraction
Published in Earle A. Ripley, E. Robert Redmann, Adèle A. Crowder, Tara C. Ariano, Catherine A. Corrigan, Robert J. Farmer, L. Moira Jackson, Environmental Effects of Mining, 2018
A. Ripley Earle, Robert E. Redmann, Adèle A. Crowder, Tara C. Ariano, Catherine A. Corrigan, Robert J. Farmer, Earle A. Ripley, E. Robert Redmann, Adèle A. Crowder, Tara C. Ariano, Catherine A. Corrigan, Robert J. Farmer, L. Moira Jackson
As more accessible ores are depleted, mining may shift to orebodies in more remote areas—particularly the Arctic (Gerard 1976; Udd 1989), the ocean floor (Goblot 1981), and the sea itself (Pearson 1975; Platzoder 1979; Doggett and Mackenzie 1995). Manganese nodules represent one of the more promising examples of these orebodies; they are found on the ocean floor at moderate to great depths, and contain sizeable reserves of cobalt, nickel, copper, and manganese. Another example is sediment basins, which may hold a wealth of metals (Loncarevic 1974). The exploitation of marine mineral deposits will result in many new environmental problems of international concern (Archer 1970; Goodier and Soehle 1971). Some indication of these challenges has been given by studies of the effects of coastal mining in British Columbia (Kay 1989), and the marine disposal of terrestrial mill wastes. Littoral dredging operations, besides damaging the site itself, may also affect a much wider area through the creation and movement of suspended particulates and may even accelerate coastal erosion. Machinery used in the operation will likely produce enough noise to disturb waterfowl and marine life, and any leakages of petroleum fuels or lubricants will produce oil-slick contamination. Offshore mining in estuaries or shallow coast areas will have the potential to cause severe disruption of sensitive ecosystems, while the mining of manganese nodules through deep-water oxygenation may lead to the leaching of toxic substances from the nodule ore. While there has been little exploitation of ocean mineral reserves, due to the considerable financial and logistical problems involved, potential impacts of deep seabed mining on the global economy have been assessed (United Nations 1986).
A Review of Low Grade Manganese Ore Upgradation Processes
Published in Mineral Processing and Extractive Metallurgy Review, 2020
Veerendra Singh, Tarun Chakraborty, Sunil K Tripathy
Manganese nodules are rock concretions formed on the sea bottom and composed of concentric layers of iron and manganese hydroxides around a core. Polymetallic nodules were discovered at the end of the nineteenth century in the Kara Sea, in the Arctic Ocean off Siberia (1868). These manganese ores contain manganese, copper, nickel, and cobalt. They occur in irregular single-layer fields at or within a meter of the sediment-water interface. These can be considered as a type of sedimentary deposit, but their polymetallic nature and submarine setting makes them different from other categories. Occurrences of economic interest are concentrated particularly in the Pacific and Indian Oceans, in the wide deep-sea basins at depths of 3500–6500 m. They are found in significant abundances in four regions of the ocean, e.g. clarion-clipperton zone, peru basin, penrhyn basin, and Indian Ocean (World Ocean Review 2014). The size of polymetallic nodules resources is still being estimated, however all are not suitable for mining. Mineable good nodules are defined as averaging at least 27–30% manganese, 1.25–1.5% nickel, 1–1.4% copper, and 0.2–0.25% cobalt. The estimation of the number of sites varied from 8 to 225, which corresponds to a total inferred resource of 480 to 13,500 million tons. These resources have various valuable metals, however economic viability of known hydrometallurgical methods still a challenge to process these ores (Polymetallic nodules, International Seabed Authority).
The economics of mining seabed manganese nodules: A case study of the Indian Ocean nodule field
Published in Marine Georesources & Geotechnology, 2019
Ranadhir Mukhopadhyay, Sankalp Naik, Shawn De Souza, Ozinta Dias, Sridhar D Iyer, Anil K Ghosh
Manganese nodules (also called as polymetallic nodules or ferromanganese nodules) constitute one of the most predominant marine mineral deposits, in terms of both commercial and academic interests. The nodules are generally potato-shaped, porous, of black earthy color with size ranging from 2 to 10 cm in diameter (Figure 1, Jauhari and Pattan 2000; Mukhopadhyay 1987; Raab and Meylan 1977). It is reported that the nodules are extremely slow growing about 1.2–3.2 mm/million years in the Indian Ocean based on U-Th isotopes dating technique (Banakar 1990) and occur on the seafloor (average water depth 5000 m) that has a low rate of sedimentation (<2 mm/103 year). The nodules contain several metals – manganese (Mn), iron (Fe), nickel (Ni), copper (Cu), cobalt (Co), zinc (Zn), molybdenum (Mo), lead (Pb), and lithium (Li), amongst others (Table 1, Mukhopadhyay, Ghosh, and Iyer 2018, and references therein). The wet density of Indian Ocean nodules is close to 2 gm/cm3, moisture dry-mass (water content) is 40% and porosity 50%. The interior of the nodules generally show three parts – layers of thick dark color ferromanganese oxides, alternating thin light color silica-rich layers, and a nucleus at the center, such as rock fragments, hardened clay or sharks’ teeth (Figure 1, Sarkar, Iyer, and Hazra 2008). The first geological model on the formation and growth of manganese nodule, with special reference to the Indian Ocean, was proposed by Mukhopadhyay, Ghosh, and Iyer (2003).
Production key figures for planning the mining of manganese nodules
Published in Marine Georesources & Geotechnology, 2018
Sebastian Ernst Volkmann, Felix Lehnen
Seafloor manganese nodules contain primarily manganese, but also nickel, cobalt, copper, and rare earth elements (Hein 2013). Those deposits may be an important future source of supply for the Western European automotive, metal and electrical industries to sustain the expansion of renewable energies and climate (Wiedicke et al. 2015; Hein 2016; Marscheider-Weidemann et al. 2016). The International Seabed Authority (ISA) is the organ which is entitled to act on behalf of mankind and whose responsibility is to organize and control all mineral-related activities and resources in “the Area” beyond the limits of national jurisdiction (United Nations 1982). In that time the EU funded several projects related to deep-sea mining as a part of their research and technological development program. The most recent projects are MIDAS (2013–2016), Blue Mining (2014–2018), and Blue Nodules (2016–2020).