Manganese nodules

Manganese nodules

1. MANGANESE NODULES Yuiyo shishak [email protected]

2. CONTENTS Introduction Origin Occurrence Economical prospects Conclusion References

3. INTRODUCTION Manganese nodules are also called Polymetallic nodules are rock concretions on the sea bottom formed of concentric layers of iron and manganese hydroxide around a core. They are composed mainly of manganese, iron, silicates and hydroxides, and they grow around a crystalline nucleus at a rate of only about one to 3 millimetres per million years. The chemical elements are precipitated from seawater or originate in the pore waters of the underlying sediments.

4. Cross-section view of a manganese nodule: Over millions of years, minerals are deposited around a nucleus

5. ORIGIN Deep-ocean water lacks significant quantities of manganese or iron Three possible sources of the manganese and iron Weathering of volcanic material on the ocean floor High concentrations of manganese and iron in hydrothermal waters at spreading centers Runoff from land Purely chemical or bacterial by product Bacteria using manganese and iron oxidation in their metabolic process theory

6. HOW NODULE FORMS The formation of manganese nodules is conceivably simple The growth process can take place n two ways: The hydrogenous process The diagenetic process

7. THE HYDROGENOUS PROCESS The metal compounds sinking through the water are precipitated Up to 10mm per million year formed due to slow deposition of metals out of sea water and characterized by a high concentration of base metals and varying Mn /Fe ratios (from 0.5 -5)

8. THE DIAGENETIC PROCESS Does not occur in the water column but within the sediments Between 10 and 100mm characterized by high Mn /Fe ratios and relatively low concentration of base metals .

9. Other classification The  Derivation  Of Metals From  Hot Springs  Associated With  Volcanic Activity  ( Hydrothermal ) , The Decomposition Of Basaltic Debris By Seawater ( Halmyrolitic ) And The Precipitation Of Metal Hydroxides Through The Activity Of  Microorganisms  ( Biogenic ). Several Of These Processes May Operate Concurrently Or They May Follow One Another During The Formation Of A Nodule

10. Nodules on the Seabed

11. CHEMICAL COMPOSITION The major elements in nodules are oxygen , manganese , iron , silica ,lesser amount of aluminium , calcium , sodium and magnesium and hence elements nickel , copper and cobalt are of greatest economic interest Manganese dioxide average 30 percent by weight Iron oxide average 20 percentage by weight Other elements average less than 2 percent by weight Fragments serves as a nucleus Nucleus made of carbonates, phosphates, zeolites , clays, and silicates

12. Occurrences Most commonly found on the ocean floors Can form on lake bottoms Highest concentrations found on vast abyssal plains in the deep ocean 4,000 and 6,000 meters Estimated that approximately two billion metric tons of manganese nodules lie on the ocean floors around the world Manganese nodules occur in many different environment including freshwater lakes , continental shelves , seamount on abyssal plains.

13. MANGANESE NODULES:RELEVANCE TO INDIA Potential Resource Of Metal In Central Indian Ocean Basin Carrying Out The Exploration And Technology Development From exploitation Of polymetallic nodules Under The Polymetallic Nodule Program(PMN) Of The Ministry Of Earth Science Only Country With Mining Site Allocated In Indian Ocean Other Site Are Claimed In The Pacific Ocean

14. ECONOMICAL USES It is these alloys, rather than manganese ore itself , which are used in most metallurgical applications. seafloor manganese nodules are often rich in manganese , iron , nickel ,copper and cobalt. Manganese is used as alloy with metals such as aluminium and copper Non metallurgical uses include battery cathodes

15. CONCLUSION Runoff that carries minerals as soluble compounds from land Found in all oceans around the world Extremely slow growth rates < 200 mm per million years Economical value in the metals Cost of extracting from deep ocean basins far outweigh the current rate on the metals market

16. REFERENCES The geology of Ore Deposits. Guilbert . And Park1975. G P Glasby ,1975. Marine manganese nodules.v,15 PP. 25-27, pp. 70 and p.142 Worldoceanreview.com>mineral-resources Geology.com>metals

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