Nodules, manganese

Manganese minerals are widely distributed oxides, silicates, and carbonates are the most common. The discovery of large quantities of manganese nodules on the floor of the oceans may become a source of manganese. These nodules contain about 24% manganese together with many other elements in lesser abundance. 

Thallium occurs in crooksite, lorandite, and hutchinsonite. It is also present in pyrites and is recovered from the roasting of this ore in connection with the production of sulfuric acid. It is also obtained from the smelting of lead and zinc ores. Extraction is somewhat complex and depends on the source of the thallium. Manganese nodules, found on the ocean floor, contain thallium. 

Deep-Sea Manganese Nodules. A potentially important future source of manganese is the deep-sea nodules found over wide areas of... 

Deep-sea manganese nodules represent a significant potential mineral resource. Whereas the principal constituent of these deposits is manganese, the primary interest has come from the associated metals that the nodules can also contain (see Ocean rawmaterials). For example, metals can range from 0.01—2.0% nickel, 0.01—2.0% copper, and 0.01—2.25% cobalt (12). Recovery is considered an economic potential in the northwestern equatorial Pacific, and to a lesser degree in the southern and western Pacific and Indian Oceans (13—18). 

G. P. Glasby and G. L. Hubred, Comprehensive Bibliography of Marine Manganese Nodules, Memoir 71, New Zealand Oceanographic Institute, Wellington, 1976, p. 55. 

M. A. Meylan, B. K. Dugohnski, and L. Fortin, Bibliography and Index to Eiterature on Manganese Nodules, Key to Geophysical Records documentation No. 6, National Oceanic and Atmospheric Administration, Washington, D.C., 1874—1975, p. 365, p. 60 addendum. 

National Oceanic and Atmospheric Administration, description of Manganese Nodule ProcessingMctivitiesfor Environmental Studies, 3 Vols., NTlS, Springfield, Va., 1977, PB-274 913, PB-274 914, PB-274 915. 

Ocean Basins. Ocean basins are primarily formed from oceanic basalts and maybe interspersed with continental remnants, ridges, seamounts, or volcanic islands rising from the depths. Average water depth is around 4000 m but the most significant mineralization is generally found at 5000 m for manganese nodules, 4000 m for biogenic oozes, and 3000 m for hydrothermal metalliferous sulfides. The area is poorly explored, however. 

Abyssal manganese nodules from the no dule belt area in the northeast Pacific. ... 

P. Halbach, G. Friedrich, and U. von Stackelberg, eds.. The Manganese Nodule Belt of the Pacific Ocean, Stuttgart, Ferdinand Enke Vedag, 1988. 

A. L. Clark and co-workers. Cook Islands Manganese Nodule Resource Assessment, Pacific Islands Development Program, Honolulu, Hawaii, Feb. 28, 1993. 

Bismuth occurs ia the earth s cmst ia a concentration of approximately 0.1 ppm on the average. Higher concentrations of bismuth occur ia oceanic manganese nodules ia a range of 0.5 to 24 ppm (see Ocean rawmaterials). The next highest concentration of bismuth is found ia siUcic rock at 0.02 to 0.9 ppm (2). 

HydrometaHurgical processes for copper can be categorized as (/) acid extraction of copper from oxide ore (2) oxidation and solution of sulfides in waste rock from mining, concentrator tailings, or in situ ore bodies (J) dissolution of copper in concentrates to avoid conventional smelting and (4) extraction of copper from deep-sea manganese nodules. 

R. Giovanoli, Natural and synthetic manganese nodules , in Geology and Geochemistry of Manganese , Vol. 1 (Eds. I. M. Varentsov, G. Grassely), Akademiai Kiado, Budapest, 1980. 

FIGURE 16.9 Manganese nodules that litter the ocean floor are potentially a valuable source of the clement. 

Chemogenic Volcanogenic Polygenic <10 >50 <10 Iron-manganese nodules, glauconite, phosphorite, nodules, phUlipsite, palagonite, celestobarite, and evaporites Pyroclastic material 38 Red clay... 

Basalt, granite, manganese nodules, shale, flint clay, iron formation materials, phosphate rock, fertilizers Calcareous loam soil, loess, polluted farmland soil, sand soil... 

Identification of sources of analytical bias in method development and method validation is another very important application of reference materials in geochemical laboratories. USGS applied simplex optimization in establishing the best measurement conditions when the ICP-AES method was introduced as a substitute for AAS in the rapid rock procedure for major oxide determinations (Leary et al. 1982). The optimized measurement parameters were then validated by analyzing a number of USGS rock reference samples for which reference values had been established first by classical analyses. Similar optimization of an ICP-AES procedure for a number of trace elements was validated by the analysis of U S G S manganese nodule P-i (Montaser et al. 1984). 

Krishnaswami S, Lai D, Somayajulu BLK (1976) Large-volume in-situ filtration of deep Pacific waters Mineralogical and radioisotope studies. Earth Planet Sci Lett 32 420-429 Krishnaswami S, Mangini A, Thomas JH, Sharma P, Cochran JK, Turekian KK, Parker PD (1982) °Be and Th isotopes in manganese nodules and adjacent sediments nodule growth histories and nuclide behavior. Earth Planet Sci Lett 59 217-234... 

Ku T-L, Broecker WS (1969) Radiochentical studies on manganese nodules of deep-sea origin. Deep-Sea Res 16 625-637... 

Kn TL, Omnra A, Chen PS (1979) Be ° and U-series isotopes in manganese nodules from the central north Pacific. In Marine geology and oceanography of the Pacific manganese nodule province (ed. J. L. Bishoff and Z. Piper), pp. 791-804. Plenum... 

Huh C-A, Moore WS, Kadko DC (1989) Oceaitic Th a reconnaissance and implications of global distribution from manganese nodules. Geochim Cosmochim Acta 53 1357-1366 Ingri J (1996) Hydrochemistry of the Kalix River. Lulea University of Technology. Report. 126p (in Swedish)... 

Another important consideration pertains to the metal content of the deposit. A deposit with a content of iron of about 20% can have little value as an iron ore since there are several deposits with 30-50% iron. Earlier, a copper ore with a minimum of 5% copper was regarded or accepted as a copper ore. However, today, thanks to advancements in technology, rocks with as little as 0.5% copper are mined and processed economically despite the fact that the price of copper, in comparison with those of some other metals, might be showing a downward trend. It is possible that in the future, other resources, which are not considered to be worth exploiting today (such as the manganese nodules or the clays), would become acceptable ores for manganese, copper, nickel, cobalt, and aluminum. 

By far the most important ores of iron come from Precambrian banded iron formations (BIF), which are essentially chemical sediments of alternating siliceous and iron-rich bands. The most notable occurrences are those at Hamersley in Australia, Lake Superior in USA and Canada, Transvaal in South Africa, and Bihar and Karnataka in India. The important manganese deposits of the world are associated with sedimentary deposits the manganese nodules on the ocean floor are also chemically precipitated from solutions. Phosphorites, the main source of phosphates, are special types of sedimentary deposits formed under marine conditions. Bedded iron sulfide deposits are formed by sulfate reducing bacteria in sedimentary environments. Similarly uranium-vanadium in sandstone-type uranium deposits and stratiform lead and zinc concentrations associated with carbonate rocks owe their origin to syngenetic chemical precipitation. 

Table 1.11 Average composition of Pacific Ocean nodules and mineralogical composition of manganese nodules.

Finally, it may be added that it is the terrestrial resources which have served and will continue to serve as practically the sole suppliers of metals and materials. Among the other resources only the manganese nodules extracted from the ocean bed have drawn serious attention the world over for exploring economic methods of processing. 

The combination of physical and chemical characteristics of nodules make impossible the application of methods of physical beneficiation such as flotation and magnetic separation to produce concentrates of valuable metals, and so chemical processing must be used. Their processing also tends to be much more energy-intensive, vis-a-vis that of conventional land-based ores. Deep-sea manganese nodules are quite unlike any terrestrial ores, both with respect to their physical characteristics and to their mineralogical and chemical compositions new processes are, therefore, required. 

Nevertheless, manganese nodules can, at best, be considered to be similar to land-based nickel laterites, and consequently most of the processing techniques that have been tried are similar to those used on lateritic ores. Reduction roasting followed by ammonia leaching, as in the Nicaro process, and high-temperature sulfuric acid leaching, as in the Moa Bay operation, have been extensively tried to process nodules. 

Figure 5.44 Summary flowsheets of hydro- and pyro-processes of manganese nodules.

Manganese ores are mined. On the ocean floor in the proximity of volcanoes there are so-called manganese nodules, which consist of oxides of manganese, iron and other heavy metals. They arise from deposition by microorganisms around a solid core (piece of mussel, shark tooth, etc.). 

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