NOAMUNDI IRON ORE MINE
Noamundi is a census town in Pashchimi Singhbhum district in the Indian state of Jharkhand.
It is also an administrative ‘block’. It is a small mining town in close to the Orissa border. It lies about 125 km from Jamshedpur and 64 km from Chaibasa. Nearby towns include Padapahar, Barajamda, Kharsawan, Gua and Kiriburu.
The major produce of this mine is iron ore (including blue dust). The mines are run by the Tata Steel and most of the residents of this town are employed by this company. In the recent past a lot of private mine-owners have also set up shop in and around the town. A Pelletizing Plant of Tata Steel to convert blue dust to pellets, suitable for use in blast furnace functioned here from 1972 to 1986 but was closed down because it was not economically viable. The town is the right on the border of Jharkhand and Orissa with some of the iron-mines spanning the two states.The portion of iron mining area of Noamundi in the state of Orissa is called Katamati.
Legend has it that when the first iron ore explorers came to this region, they were amazed to find the local tribal population (Adivasis) using iron axes. When the explorers asked the tribals where they had found the ore, they pointed to a hill nearby and called it Noamundi, which literally means ‘that hill’ in their language.
The native tribals are known as Ho people and their language is also known by the same name – Ho.
Noamundi is located at 22.15° N 85.53° E. It has an average elevation of 487 metres (1597 feet).
Noamundi is located in the heart of Saranda forest, which is the densest deciduous forest of Asia. ‘Saranda’
in the local tribal language means ‘The land of 700 hills’.The administrative boundary of the Saranda reserve
forest ,however,lie a few kilometers away.
In operation since 1925, the Noamundi Iron Mine (NIM) is a fully mechanised mine. The NIM supplies the principal
raw materials for iron and steel making to the Company’s steel works and other steel industries. Systematic mining
and scientific processing of the ore enables it to conform to consistent physical and quality norms. The mine
has belt conveyors, and loading onto railway wagons is fully mechanised. It produces sized ore (-40mm to + 10mm),
LD ore (-40mm to +20mm) and blended fines (-10mm). The mining operations are carried out in series of 12 meter
high benches 150mm diameter holes are drilled and blasted with explosives, the ore is then shovelled and trucked.
The mine has the capability for dry processing of rich grade fine ore.
The NIM also processes and enriches the quality of the ore mined from the company’s Katamati Iron Mine. The ore from this mine is transported to NIM and processed along with NIM ore at its Wet Processing and Dry Processing plants.
GEOLOGY OF NOAMUNDI
Banded Iron Formation (BIF) forms an important component of Archean schist belts all over the world. They are particularly well developed in India. Extensive outcrops are found in the state of Jharkhand, Karnataka, Madhya Pradesh, Maharashtra, Orissa and Tamilnadu. Studies in India have mainly centered round economic aspect of the iron ores, while features like condition of deposition, nature of depositional basin, stratigraphy, structure, tectonics, geochemistry, mineralogy, digenetic changes, metamorphism and palaeobiology have been some what neglected and the information available on these aspects is fragmentary. Iron-formation is important not because it hosts rich deposits of iron ore but signifies special conditions of deposition on a global scale during a particular period in earth’s history which was not repeated in later times. The origin structure and tectonic environment of the Banded Iron Formation (BIF) is more than local interest.
A major part of the iron ore production of India is obtained from Precambrian meta-sedimentary rocks of the Singhbhum region of eastern India. Percival (1931) suggested that the most probable source for the bulk of the iron and silica in the banded iron formations was hot magmatic waters and vapors ejected under submarine conditions whereas the banded structure was due to rhythmic precipitation of iron and silica. Jones’ (1934) view was that the banded iron formations were marine sedimentary deposits and the banding was caused by rhythmic precipitation. Dunn (1935, 1941) proposed a replacement mode of origin of the banded iron formation in which secondary silicification of altered tuffs and phyllites along bedding planes resulted in banding. Spencer and Percival (1952) suggested that algae and bacteria played a large part in breaking down original basic rock from which silica and iron were derived in colloidal form, while submarine volcanism added a further direct supply of these materials. Banding was th ought to be due to an intermittent supply of mixed material, with more rapid settling of the iron than of the siliceous colloids.
Regional structural studies have not yet been attempted. Those available are restricted to smaller belts: Sukinda valley (Chakraborty et al, 1980), Gurumahisini Badampahar (Saha and Ray, 1984; Majumder, 1985), Jamda-Koira Valley (Murty and Acharya, 1975), Sandur (Roy and Biswas 1983).
Large regional fold structure in the younger schist belts appear to be governed by the shape of the basement gneiss. Earlier folds are refolded. Plunges are highly variable and in some cases nearly vertical. Banded Iron formation has used as a marker horizon for delineating structure and to evolve stratigraphy. The structure of the Dharwar rocks in the Bababudan region is described as dominated by upright mainly open folds, with strongly curved hinge lies within steep fold axial surfaces. Repetition of beds through isoclinal folding and thrusting, pointing to horizontal as opposed to vertical tectonics in Archean has been inferred . Re-evaluation of these various model is necessary. Hence, this project is oriented to correlate regional basin structure of Iron Ore Synclinorium using small scale structures.
Noamundi Iron Ore Mine
This area falls within the Noamundi Iron ore deposit which is of extreme economic importance to India, since it contains very rich and one of the best deposits of iron ore. The Noamundi iron ore deposit is situated in the southern part of the Singhbhum district, Jharkhand. Here mining started in the year 1925 and the mine was mechanized in the year 1967.
Geographically Noamundi is situated in the South Singhbhum district of Jharkhand (Map-1) about 125km from Jamshedpur and the nearest station is Noamundi. Noamundi is connected with road with Jamshedpur. The area is also accessible by road from Bileipada, Keonjhar Dist., which is situated on the NH-215. It is confined within the longitude 85° and 86° and latitude of 21° 45′ and 22° 30′ and included in the survey of India toposheet no. 73 F/12.
The area falls under tropical climate zone. In general the climate of the area is arid. The winter temperature goes down 100 where as in summer the temperature rises up to 400 or even more. The annual rainfall varies from 100 to 200 cm. In this area the drainage density is low and is mainly governed by streamlets. The drainage system remains dry during winter.
Noamundi area is under deep forest and falls within Sunda forest. The hilly area is covered by relatively dense forest, which flourishes rapidly during the monsoon. At many places thorny bushes were found. Important floras include Sal, Mango etc. There was apparently no cultivated land in this area.
The most important banded iron formation of the Singhbhum region are associated with the Noamundi group, which is made up of lower formation of shale-phyllite and tuff (Lower Shale) and an upper formation of shale, chert and tuff (Upper Shale) between which is sandwiched a thick banded hematite jasper (BHJ) formation. The lower shale formation is poorly exposed in the eastern part of the Noamundi basin where its thickness does not exceed 30 to 50 m. this formation is made up of considerable amounts of interbedded, altered acidic and basic lave flows and tuffs. The iron content of these altered volcanic rocks increases upward to a certain extend that the upper part of the formation is sometimes classified as “soft” and “shaly” iron ore (Percival, 1931). The BHJ formation ranges in thickness between 300 and 400m (widths of up to 1,000 m in places possibly are caused by repetition owing to folding). In the eastern part of the basin the BHJ occurs only in a number of disjoined outcrops but in the western and southern part it forms a long and narrow ridge, 800 to 1000 m high. This extensive banded iron formation, much thicker than that of the Gurumahisani group, is similar to the Lake Superior type (Gross, 1965). There are numerous shale layers within the BHJ made up of fine-to medium grained tuffaceous and pyroclastic materials which vary in colour from white to cream and purple. Massive hematite ore bodies of various sizes occur at or near the upper surface of the BHJ formation. The Upper Shale formation occurs in the core of the Noamundi basin and consists of considerable cherty and tuffaceous matter and interlayered beds of altered lava (Dunn, 1940). Percival in 1976 gave the description of the Noamundi area following the stratigraphy given by Jones which is mainly shales and lava flows with connected intrusive dolerite, sandstone, conglomerate with shaly ash bands.
Percival (1976) has given the following succession for Noamundi,
Ultra basic igneous rocks
Granitic rocks shales epidiorites and ash beds
Banded hematite quartzite with Fe ore bodies
Shales with occasional thin sandstone and
Calcareous band Limestone (in places)
Purple sandstone with basal conglomerate in parts and
Sometimes with bands of conglomerate
Hornblende and mica schist and quartzite
Iron ore series
(Newer Dharwar) Archean
Noamundi Iron Ore Mine of TISCO is situated in Singbhum district of Jharkhand belongs to Jamda – Koiba IOG basin of Eastern India Shield (EIS) – a horseshoe shaped belt trending NNE – SSW. The eastern limb is the normal one whereas the western limb is overturned towards SE. The fold axis plunges towards NE. The western limb is more or less continuous while the eastern limb is discontinuous. The degree of deformation increases towards south.
The total mining area is extended over about 600 sq. km. within the total leasehold area of 1100 sq. km. Though the lease area is now extended with the introduction of another 700 sq. km. along the western side. There are two N-S trending hill ranges – the height of the eastern and western hills are about 747m and 640m respectively. Vast deposits of iron ore formed in these two hill ranges in association shale and quartzite belong to IOG. The dip of the ore body varies from 22° – 28° and dips towards west. The thickness of the iron ore deposit is about 100m.
The iron ore of this area is mainly hematite in nature with minor quantity of goethite, siderite, specularite and limonite – the basement rock being Banded Jasper Quartzite. The ores are intercalated with chert and shale. Often the cherty bands are replaced by hematite to give high-grade ore. Iron ore deposits overlying the BHJ are mainly the product of supergene alteration and exploration and exploitation continues up to the BHJ zone. Thus the ores are confined only in the top portion. The ores are laterised to varying degree by the action of weathering and percolating into the iron ores through cracks and cavities.
Different types of ores
The varieties of ore met within the investigated area are –
. Hard ore (massive and laminated)
. Soft ore
. Friable and flaky ore
. Blue dust.
Laterite is most common especially at the hill top as cap rock lying over the iron ore zones. Pockets of ochre of
various types are found. These are the deleterious materials of iron ore. Pockets of kaolin and other clay minerals are
also found, which generally brings down the overall ore grade. Shale bands of small thickness are found inter-banded with
the iron ore and also thick, compact laminated shale beds are seen at places. The overburden or the wastes consists of soil
(top soil), laterite and shale.
(i) Hard ore
The hard ore is generally of steel grey colour and compact or massive, sometimes thickly banded in nature.
Very often the ore is highly broken and jointed and sometimes literalized near the surface. It contains about 65 – 68% of
Fe2O3 and 0.2 – 0.25 % of Al2O3.
The soft ore is generally hydrated oxides of iron as goethite and limonite etc. this type of ore is
usually vesicular or porous and is often lower in grade. It contains about 62 -65% of Fe2O3, 4 – 6% of
phosphorous with higher Al2O3 content.
(iii)Friable or Flaky ore
These ores are generally flaky in nature with a wider range of Al2O3 and phosphorous. Fe2O3 content generally
varies between 58 – 63 %.
This variety is blue in colour, fine and powdery in nature. It contains about 67% or more Fe2O3 but Al2O3 content
ranges from 1.2 – 1.5 % or at places more than 2 %. It occurs as thin bands only at the deeper levels of the
ore zone and at selective places lie over the BHJ.
The general sequence of the ore zone is as follows:
Laterite /Canga /Soil
Upper Shale (?)
Iron Ore Zone
Banded Hematite Jasper
Regional Geology and statrigraphy
The iron ore and manganese mines of Noamundi and Joda belong to the Iron Ore Group (IOG). In Eastern India Shield (EIS) the IOG of rocks are distributed in three major iron ore basins surrounding the Singbhum craton.
Among these three major basins the largest basin occurs in the western part, called Noamundi Basin or Jamda-Koila Basin. The other two basins are GuruMahisani-Badampahar-Sulaipath in the Eastern part and Tamka-Daitari in the Southern part. However, Chakraborty and Majumdar (1986) considered the last two basins to be part of the same Green Stone Belt and now apparently detached due to the superimposition of the younger rocks. The IOG consists of various metamorphosed sediments, volcanics and intrusives. The volcanics ranges from rhyolitic to komatitic through tholeiitic where as the intrusives ranges from intermediate through basic to ultrabasic in nature. In the Noamundi Basin two phases of deformation is evident. The general trend of the basin is NNE-SSW and it basically represents a large regional synclinorium overturned to the SE with the fold axis plunging towards NE. The F1 and F2 folds are more or less coaxial and coplanar too but the F3 folds are of cross-fold type having WNW-ESE axial trend. In Go rumahisani-Badampahar basin the general trend is along NNE-SSW. Two phases of deformation are present. The earlier regional F1 folds are cross-folded by open W-NW trending F2 folds. The southern most Tamka-Daitari shows nearly E-NE trending F1 folds. Previously Singbhum granite was supposed to intrude into IOG rocks, but later in the western part findings of pebbles and cobbles of SG in the glacial conglomerate horizon of IOG proved that at least a part of SG (type-A) formed the basement of IOG where SG type-B intruded the IOG rocks.
Dunn(1929) and Dunn and Dey (1942) were the pioneer in the study of the terrain. Later Sarkar and Saha (1962) did extensive work in the area. They proposed that IOG of rocks to the south of the thrust are older than the similar rocks in the northern side of the thrust and referred to these northern rocks as the Singbhum Group. They considered that Singbhum Group consists of an anticlinorium south of a synclinorium of Dalma volcanic rocks, all overturned to the south.
Ore Characterization and its Formation
Banded iron formation is a sedimentary rock that was commonly deposited during the Precambrian. It was probably
laid down as a colloidal iron-rich chemical precipitate, but in its present compacted form it consists typically of
equal proportions of iron oxides (hematite or magnetite) and silica in the finely crystalline form of quartz known
as chert. Its chemical composition is 50% silicon dioxide (SiO2) and 50% iron oxides (Fe2O3 and Fe3O4), to give a total
iron content of about 30%. Banding is produced by the concentration of these two chemical components into layers about
1-5 cm (1/2-2 in.) thick; typical banded iron formation consists of pale silica-rich cherty bands alternating with
black to dark red iron-rich bands (see illustration). These contrasting layers are sharply defined, so that the rock
has a striped appearance; banded iron formation is normally a hard, tough rock, highly resistant both to erosion and
to breaking with a hammer.
The world’s iron and steel industry is based almost exclusively on iron ores associated with banded iron formation.
Banded iron formation itself may be the primary ore, from which hematite or magnetite is concentrated after crushing.
But the main ore now mined globally is high-grade (greater than 60% iron) material that formed within banded iron
formation by natural leaching of its silica content.
The formation of high grade iron ore from the primary Banded Hematite jasper or Banded Hematite Quartzite is still not
established with firm evidences. Though most commonly accepted theory is that high-grade hematite ores of the Iron Ore
Group in the Noamundi area, Jharkhand State, India, are hosted by a laterally extensive, 220m thick
banded iron formation in a folded greenstone belt succession of Paleoarchean age. Single ore bodies, which are up to
3 km long along strike and several hundred meters wide, depending on dip of the beds, are stratabound and composed
of two major ore types, namely hard hematite ore that is of ancient geological origin and ores related to recent
weathering along a lateralized Cretaceous-Cenozoic land surface. The ancient hard hematite ore bodies comprise
laminated hematite ores in which microplaty hematite is dominant, and massive ores composed almost entirely of martite.
Supergene ores, in contrast, are comprised of goethite-rich duricrust and soft saprolitic hematite ores
representing the leached zone of the Cretaceous-Cenozoic laterite profile.
Hard hematite-martite ores formed by hydrothermal replacement of banded iron-formation protolith, not only
through leaching of silica, but also introduction of iron by hydrothermal fluids of meteoric origin.
The hydrothermal fluids evolved from one that was warm, acidic and reducing, to allow for transport of ferrous iron
to one that was cooler and more alkaline to allow for dissolution of silica and precipitation of ferric iron, i.e.
hematite and martite. Hematite iron ore pebbles in an overlying Mesoproterozoic conglomerate attest to the antiquity
of the hard ores.
In Cretaceous-Cenozoic times leaching of silica and/or carbonate from partly mineralized banded iron-formation gave
rise to formation of soft saprolitic ores. Weathering took place under the influence of highly reducing and acidic
meteoric water, which is typical for lateritic soil profiles developed under humid tropical climatic conditions with lush plant cover.
Noamundi iron mine is an open cast mine mining was started since 1925. Fe-ores are excavated through highly
mechanized open cast mining by box cut method, developing benches after removal of overburden. The benches are developed
along the strike to mine more area and for better quality control. The bench width is 12 km where the bench
height is around 10-12 km. The general slope of the pit is 45o. Ore of different types are excavated first by blasting
and then blended in proportion before dispatching in to the treatment plant. Generally 40% of hard ore is blended with
60% of soft or friable ore and are dispatch from mine face with shovel and primary dumpers (50-60 tones capacity).