Manganese nodules

1. MANGANESE NODULES
Yuiyo shishak
yuiyoshishak@yahoo.com

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:
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

11. Nodules on the Seabed

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

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.

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