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:
I. The hydrogenous process
II. 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
12. 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
13.
14. 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.
15.
16. 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
17. 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
18. 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
19. 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