Journal of Minerals and Materials Characterization and Engineering, 2012, 11, 1133-1142
Published Online December 2012 (http://www.SciRP.org/journal/jmmce)
Integrated Mineralogical Characterisation of Banded Iron
Ores of Orissa and Its Implications on Beneficiation
J. K. Mohanty1*, M. S. Jena1, A. K. Paul2
1Council for Scientific and Industrial Research (CSIR), Institute of Minerals and Materials Technology, Bhubaneswar, India
2Department of Geology, Utkal University, Bhubaneswar, India
Received July 24, 2012; revised August 29, 2012; accepted September 12, 2012
ABSTRACT
Iron is a primary raw materia l for steel industry. In crease in demand for steel p uts pressur e on iron resources of Ind ia in
respect of its grade and reserve. With increase in d emand for good grade of ore vis-a-vis its limited reserve, the utiliza-
tion of low to medium grade iron ores is the order of the day with adoption of advanced beneficiation techniques. In
order to find out the effective way of utilization, an in depth mineralogical study is essential as it throws light on the
mineralogical peculiarities associated with the ores which affect the resultant beneficiation technique as well as the final
product. In order to have a detail insight into the different mineralogical attributes, various characterisation studies
megascopic, microscopic (both optical & electron), XRD, mossbauer and VSM are undertaken on the iron ores from
different iron ore formations of Orissa. Importance of integrated mineralogical characterisation in beneficiation of iron
ores is discussed.
Keywords: Iron Formation; Characterization; Beneficiation; Mossbauer Spectroscopy; Orissa
1. Introduction
Iron is the second most abundant metallic element in the
Earth’s crust and accounts for 5.6% of the lithosphere.
Iron like most metals, is found in the Earth’s crust only
in the form of an ore i.e. combined with other elements
such as oxygen or sulfur. Hematite an d magnetite are the
two important iron ores from which iron is extracted. Of
these, hematite is considered to be superior owing to its
high reserve. Hematite is the main iron ore which is ex-
tensively used for manufacture of iron and steel in India.
The grade/quality of ore determines on different iron ma-
king processes. W ith the iron and steel industries are be-
coming increasingly conscious about the need for im-
proving productivity, the approach is towards obtaining
cleaner ore with higher Fe content having least gangue
and of homogeneous and consistent quality.
The world reserve base of crude iron is estimated to be
370 billion tones [1]. It has been estimated th at the world
resources are in excess of 800 billion tonn es of crude ore
containing more than 230 billion tonnes of iron. Iron ore
deposits are distributed in different regions of world un-
der varied geological conditions and in different geo-
logical formations. The largest concentration of ore is
found in banded sedimentary iron formations of Precam-
brian age. These formations constitute the bulk of world
iron ore resources. The top countries in the world in or-
der of their iron resources are given in the Figure 1.
Among the iron ore producing countries, India ranks
fourth in terms of quantity produced following China,
Brazil and Australia.
India has large reserves of good quality iron o re. India
is endowed with huge resource b ase of 25.24 billion tonnes
of iron ore of which 7.06 billion tones are reserve and
18.18 billion tones are remaining resources [1]. These
iron ores occur in different geological rock groups/
W orld resource s of iron ore
US A
Australia
Br a zil
Chi na
India
Sw eden
V enezuela
Kaza khstan
Russia
Ukrain
Others
Figure 1. Distribution of iron ore resources in different
countries of world.
*Corresponding author.

J. K. MOHANTY ET AL. 1134
formations in different time domains. On the basis of
mode of occurrence and origin, the iron ore deposits are
divided into five groups viz. Banded Iron Ore Formation
(BIF), sedimentary iron ore deposits of sideritic and
limonitic composition, lateritic ore derived from sub-
aerial alteration of gneiss, schist etc., Ti-V-magnetite de-
posits and fault and fissure filling deposits. Among these,
the largest concentration of economic deposits is found
associated with volcano-sedimentary Banded Iron For-
mation (BIF) of Precambrian age. The BIF, mainly com-
prising of Banded Hematite Quartzite/Banded Hematite
Jasper (BHQ/BHJ) contains iron in the range of 25% to
40%. By supergene enrichment, the total iron content of
the BHQ/BHJ has in many places gone upto about 55% -
65% making them very good quality ore. Most of the
Indian deposits are similar to those of Lake Superior
Type. Extensive outcrops of BIF are found in the states
of Orissa, Jharkhand, Chhatisgarh, Karnataka, etc. The
most common names used in India to designate BIF are
BHQ and BMQ. Hematite accounts for more than 98%
of the total reserve. Major hematite resources are located
mainly in Orissa (33%), Jharkhand (28%), Chhatisgarh
(19%) and Karnataka (11%).
Banded Iron Formations are chemically precipitated
enigmatic rocks constituting alternate iron-rich and iron
—poor (amorphous silica rich) layers. This dichoto-
mous compositional dowering is usually expressed on se-
veral scales at any given outcrop, from fine sub-milli-
meter-scale varve like laminae to meterscale bands. Even
on a microscope scale, the boundary between the ferru-
ginous and siliceous layers is distinctly observed.
Orissa holds a lion share of the total Indian reserve.
The iron ore resources are distributed in three iron ore
formations viz. BIF 1, BIF2 and BIF 3 (Figure 2). The
iron ores deposits are distributed mostly in Keonjhar,
Sundergarh, Jajapur and Mayurbhanj districts. A small
deposit is present in Koraput district which has been very
scantily studied. Due to various socio-economical con-
straints and poor locational dynamics, it is at present not
being explored/exploited.
ORISSA
Figure 2. Iron ore occurrences in Orissa.

J. K. MOHANTY ET AL. 1135
Due to pressure of bullish Iron and steel industry for a
continuous supply of good grade raw material, full scale
mining activity is going on in the northeastern Orissa
where most of the iron ore mines are situated. Keeping
abreast with the demand, Govt. has planned for annual
production of 110 MT steel by 2020 which will be re-
quiring 170 million tonnes of iron ore. A target set in the
policy suggests a production of 300 million tonnes of
iron ore by 2019-2020 to meet export and domestic de-
mand. Looking into the demand for good grade which is
much less compared to medium and low grade ores,
enough stress is being laid on the utilization of these
leaner ores to augment the resource position to support
the ensuing steel production. As these ores can not be used
straight way, they need upgradation of Fe content which
can be achieved by various beneficiation techniques. The
basis for any effective beneficiation process lies in a de-
tail mineralogical and chemical characterisation of the
raw material. The paper gives an account of detail mi-
neralogical characterisation of iron ores from the three
iron ore formations and its significance in optimum bene-
ficiatio n o f the low/me dium grade ores .
2. Materials & Methodology
A few iron ore samples are collected from different loca-
tions of the three iron ore formations for their detail mi-
neralogical and chemical characterisation which finally
will give an insight to their beneficiation characteristics.
Mineralogical characterisation is very important in study
of these types of ore which will provide information
about the mineralogy and different textural attributes to
decide upon the right choice of beneficiation practices.
The selection of suitable beneficiation processes depends
on the physical characters of iron minerals and quartz.
An integrated approach towards mineralogycal charac-
terisation was adopted using various techniques such as
optical microscopy, XRD, Electron microscopy, Moss-
bauer spectroscopy and VSM. The results of mineralogical
characterisation have some direct application in iron ore
processing.
XRD was carried out with Philips PW3710 X ray unit
having Mo target (α1 0.7093 and α2 0.71359) and oper-
ated at 45 kV and 35 mA. The operating parameters are
Divergence slit (1/4) and receiving slit of 0.2, step size
(2θ) of 0.020 and 1s/step with continuous scan from 2θ 6
to 40.
Electron microscopic study was carried out by JEOL
JSM 6501 operated at 15 kV with 11 to 14 mm working
distance after the sample is coated with carbon.
Mossbauer spectra have been recorded by a conven-
tional constant acceleration spectrometer at 300 K using
25 mCi 57Co source embedded in Rh matrix. About 60 -
70 mg of powders from samples was sandwiched inside a
copper ring of 12 mm inner diameter with cello-tape on
both sides. The experimental data were fitted with a least
square fitted computer program considering Lorentzian
line shapes of the spectrum and parameters were calcu-
lated by taking the spectra of bcc iron as a calibration.
Magnetization study was carried out to find out the
natural magnetic behaviour of the samples containing
different iron phases. For this purpose, room temperature
magnetization as a function of applied field has been
measured for all samples for both positive and negative
field range to get the hysteresis curves (Figure 7). A vib-
rating sample magnetometer (VSM, ADE Technology,
USA) has been used for magnetization measurement upto
a highest field of 1.75 T.
3. Results
The three iron formations differ in their mineralogy (both
ore and silicate bands) and geological features. The dis-
tinction between them is based on iron mineralogy and
silicate phases, degree of metamorphism and effect of
weathering/alteration. BIF I is represented by magnetite
and chert with little martite, hematite and goethite. Occa-
sional presence of pyrite is observed. It has undergone
metamorphism in moderate to high temperature and pres-
sure conditions. BIF II is mostly martitised magnetite and
quartz. Martite is a variety of hematite pseudomorph after
magnetite. It has witnessed metamorphism under low to
moderate temperature and pressure. BIF III that mostly
consists of hematite and jasper (a red variety of quartz)
shows almost no sign of metamorphism. Results of detail
mineralogical study are given below.
3.1. Megascopic Study
Banded iron formation is a system where both iron and
silica are involved to give rise to a banded appearance. It
implies that iron rich and iron poor-silica rich layers ap-
pear alternatively giving rise to a banded nature to the
proto-ore. Figure 3(a) depicts a megascoipc view of a
banded iron ore where both iron rich grey and silica rich
red bands are alternatively present giving a banded ap-
pearance to the ore. Figure 3(b) is a megascopic view of
a banded hematite quartzite where iron ore bands are
fractured and fragments of iron ore are embedded in
quartz matrix. The ore generally breaks along the ban-
ding which is generally the iron and silica boundary. The
scale of banding is very important for physical benefi-
ciation perspective as well as downstream operations. The
banding varies from mega to micro depending on the
thickness of the corresponding layers. Mega or coarse
banding has an advantage that the constituent parts can
be easily separated where as separation is difficult if the
bands are very thin. Simi larly if the iron or e is fragmented
to a very fine size and intermixed with quartz, then se-
paration of iron from quartz will be very difficult.

J. K. MOHANTY ET AL. 1136
(a)
(b)
Figure 3 (a) Banded iron ore showing coarse bands of iron
(steel grey) and silica (red), (b) Deformed banded ore show-
ing fragments of iron ore (steel grey) are set in a matrix of
quartz (white).
3.2. Microscopic Study
Representative polished sections are prepared and mi-
croscopic study was undertaken to find out the mineralogy,
texture/micro-structure and modal distribution of the mi-
nerals in the ore.
3.2.1. Op t i ca l M i cr oscopic Stud y
Microscopic study reveals that the ores are mainly com-
posed of iron oxide-hydroxide phases in different pro-
portions with varying amounts of silicate minerals like
quartz and clay. Hematite, magnetite and goeth ite are the
major iron minerals. Goethite, the major mineral in iron
ore samples from Hirapur area shows well developed col-
loform banding, a characteristic texture indicating col-
loidal precipitation (Figure 4(a)). The banded iron for-
mation is due to presence of alternate iron rich and iron
poor-silica rich bands (Figure 4(b)) and this feature is
very characteristic of precipitation of a solution alterna-
ting with iron rich and silica rich materials [2]. The
banded iron ores from different deposits exhibit macro
banding to microbanding (Figure 4(c)). The scale of band-
ing is very important from beneficiation point of view as
during communition process, the coarse bands will sepa-
rate out considerably where as the microbands get cam-
ouflaged between iron rich and iron poor fractions
s
I
(a) (b) (c)
H
S
(d) (e) (f)
Figure 4. (a) Colloform banding of goethite in iron ore, (b) Alternate bands of iron rich and silica rich in banded hematite
jasper, (c) Alternate bands of hard laminated ore showing contrasting mineralogical association and texture, (d) Specular
hematite grains in a silica matrix in a laminated ore, (e) Distribution of euhedral hematite in a silicate matrix in BHJ, (f)
Hematite grains join together to give a chain appearance in quartz matrix, I—Iron Rich, S—Silica Rich, H—Hematite.

J. K. MOHANTY ET AL. 1137
leading to difficulty in selection of unit operations for
processing. Figure 4(d) depicts skeletal hematite in sili-
cate matrix. Figure 4(e) shows presence of euhedral he-
matite grains in a silica matrix. When bigger crystals join
together head on, they look like a ropy chain (Figure
4(f)). Iron ores representing BIF 1 consist mostly of mag-
netite and quartz. Besides a few pyrite grains are found to
be present. Hence this type of ore is difficul t to beneficiat e.
3.2.2. Electron Microscopic Study
Scanning electron microscopic study was carried out to
find out the textural relation between major mineral
phases of BIF in a fine scale. Presence of very fine he-
matite grains with in quartz (Figure 5(a)) and irregular
shaped quartz in hematite (Figure 5(b)) is obs erved. The
hematite grains in silicate matrix are extremely fine
grained. So it is very difficult to liberate the hematite
grains for its upgradatio n. Figure 5(c) shows an enlarg ed
hematite crystal having inclusions of quartz where as
presence of irregular shaped hematite is found to be pre-
sent within quartz grains and also between quartz grains
(Figure 5(d)). These findings have a great influence on
beneficiation of this type of iron ores. The study indi-
cates that total separation of iron minerals from such
silicate association is very difficult and may not be eco-
nomic as this may involve lot of grinding to finer size for
complete liberation as selection of unit operations for
physical beneficiation is based on liberation of the mi-
neral grains.
3.3. XRD Study
XRD of iron ore samples from iron formations was car-
ried out and the major minerals are identified. XRD study
H
Q
H
(a) (b)
Q
H
(c) (d)
Figure 5. (a) SEM of BHJ sample showing random distribution of fine hematite grains in quartz matrix, (b) SEM showing
distribution of irregular quartz grains in hematite, (c) SEM showing distribution of very coarse as well as fine hematite
grains, (d) Irregular distribution of coarse and fine hematite grains in a quartz matrix in BHJ. H—Hematite, Q—Quartz.

J. K. MOHANTY ET AL. 1138
indicates that samples from Hirapur (HP) are predomi-
nated by goethite with minor amounts of hematite. Sam-
ples representing BIF 1 have magnetite as the major mi-
neral phase with minor amounts of hematite and quartz.
Hematite, goethite and quartz are the principal minerals
of BIF 2. Depending on the degree of alteration, the pro-
portion of hematite and goethite varies in the samples.
The samples representing BIF 3 mostly consist of hema-
tite and quartz. The quartz is actually jasper; a variety of
quartz which imparts a brilliant red colour to the banded
ore after good polish. From the XRD study, it is observed
that hematite and quartz are the major minerals in BIF 2
& 3 where as magnetite is principal mineral in BIF 1.
Presence of minor amounts of goethite is also observed.
3.4. Mossbauer Study
Mossbauer spectroscopy has been used for identification
of iron bearing mineral phases [3]. Earlier workers have
reported mineralogy of Iron ores from banded iron for-
mations of Orissa by means of Mossbauer spectroscopy
[4]. For the present investigation, selected samples from
three iron ore formations were tak en for Mossbau er stud y.
The spectra and results of MS study were given in Fig-
ure 6 and Table 1.
From the above study, it is observed that samples from
Figure 6. Mossbauer spectra of iron ore samples from different iron formations.

J. K. MOHANTY ET AL. 1139
Table 1. Mossbauer parameters of iron ore samples from different iron formations.
Sl. No. IS (mm/s) QS (mm/s) LWD (mm/s) Bhf (T) Area (%) Mineral
JKM-1 0.3489 –0.0940 0.2648 51.6 100 Hematite
JKM2 0.3496 –0.0924 0.2596 51.6 100 Hematite
JKM3 0.3411 –0.0812 0.3103 50.7 16.8 Hematite
0.3370 –0.1349 0.3811 37 33.8 Goethite
0.3387 –0.1353 0.3784 33.6 36.9 Goethite
0.4512 –0.0514 0.3307 28.4 12.5 Unknown
JKM4 0.3497 –0.0431 0.3041 51.6 47.2 Hematite
0.2221 –0.0408 0.2064 48.6 17.3 Magnetite
0.6673 0.0188 0.3258 46.2 35.5 Magnetite
JKM5 0.3490 –0.0962 0.3307 51.6 100 Hematite
JKM6 0.3478 –0.0796 0.3051 51.3 85.3 Hematite
0.3478 –0.1374 0.4555 37.5 14.7 Goethite
JKM7 0.3474 –0.0953 0.3699 50.4 59.5 Hematite
0.3448 –0.1344 0.2328 37.8 16.7 Goethite
0.3397 –0.1445 0.4983 35.4 23.9 Goethite
JKM8 0.2698 –0.0067 0.3278 49.3 44.3 Magnetite
0.6360 0.0059 0.3783 45.8 55.7 Magnetite
JKM9 0.3498 –0.0870 0.3195 51.5 100 Hematite
JKM10 0.3553 –0.1037 0.2626 51.6 35.2 Hematite
0.3402 –0.1393 0.3006 38 30.3 Goethite
0.3309 –0.1387 0.4294 36 25.1 Goethite
0.2550 –0.2041 0.3307 31.8 9.4 Goethite
BIF-I (JKM4 & JKM8), BIF-II (JKM9 & JKM10), BIF-III (JKM1, JKM2, JKM5 & JKM6), Hirapur (JKM3 & JKM7).
BIF 1 mostly consist of magnetite. Samples from BIF 3
have hematite as the principal mineral phase with minor
amounts of goethite. Iron ore from BIF 2 consists of he-
matite and goethite. Iron ore sample from Hirapur con-
tains both hematite and goethite. Qualitative and quanti-
tative estimation of minerals by mossbauer study cor-
roborates the findings of microscopic and XRD study and
also gives an idea about the relative abundance of the
iron minerals in three iron formations. It also gives an
idea about the degree of crystallinity and structural state
of the iron minerals. This information along with VSM
data may be useful for better understanding of the physi-
cal characters of iron minerals, which leads to selection
of proper communition as well as beneficiation process.
3.5. VSM Study
Natural iron minerals display a very wide range of mag-
netic properties. The minerals can be satisfactorily dis-
tinguished from one another by laboratory induced mag-
netization at room temperature [5]. The hysteresis curves
(Figure 7) and relevant data generated by VSM study are
given in Table 2. The VSM data indicate that samples
from BIF 1 possess magnetic character due to presence
of magnetite as the principal iron mineral. Samples from
BIF 2 have some magnetic behaviour due to presence of
minor to trace amounts of magnetite/martite. Samples
from BIF 3 and Hirapur are less to nonmagnetic in char-
acter. This indicates that samples from different iron
formations have differential magnetic behaviour and
need differential heating to simulate magnetism in them
which will help in their separation from the associated
gangue mineral, quartz (highly nonmagnetic) during
beneficiation process. Undoubtedly the results from
VSM studies give an indication for selection of the type
of magnetic separator to be used based on the magnetic
intensity range for its up-g radation.

J. K. MOHANTY ET AL. 1140
JKM-04
JKM-08
-2.0 -1.5 -1.0 -0.50.00.51.01.52.0
-80
-60
-40
-20
0
20
40
60
80


H (T)
M (emu/g)
JKM-06
JKM-07
JKM-10
-2.0 -1.5 -1.0-0.50.00.51.01.52.0
-0.9
-0.6
-0.3
0.0
0.3
0.6
0.9


H (T)
M (emu/g)
JKM-09
-2.0 -1.5-1.0-0.50.00.51.01.52.0
-4
-2
0
2
4
H (T)
M (emu/g)
Figure 7. Hysteresis curves for different iron ore samples.
Table 2. VSM data of iron ore samples.
Sample Magnetization at 1.75 Tesla, Ms (emu/g) Remanent Magnetization, Mr (emu/g) Coercive field, Hc (Oe)
JKM1 0.6112 0.06825 88.92
JKM2 0.6215 0.1464 474.46
JKM3 0.4862 0.009 121.36
JKM4 59.01 4.363 89.63
JKM5 0.7105 0.1861 1775.2
JKM6 0.6877 0.1571 197.69
JKM7 0.7067 0.07348 557.88
JKM8 84.07 5.872 56.75
JKM9 4.877 1.049 162.46
JKM10 0.8119 0.0847 122.17
(Sample Nos are same as given in Table 1).
3.6. Chemical Analysis
Chemical analysis data indicate the beneficiation pro-
cess as well as operating parameters to be adopted, num-
ber of stages required for cleaning, grade, recovery and
cost of the products, evaluation of process etc. Chemical
analysis of the concentrate and rejects helps the re-
searchers/industrialists to evaluate and develop the pro-
cess flowsheet. Keeping this in mind, representative sam-
ples from different BIFs are analysed for their major
element composition by XRF. The major elements data
are given below in Table 3.
It is observed that SiO2 varies from 1% in massive ore
to 75% in siliceous ore. Similarly Fe2O3 varies from
21.38% in siliceous ore to around 97% in massive ore.
However within these extremes, both silica and iron ex-
hibit wide variation and the relative proportion of these
elements affect the grade and demand of the ore. Al2O3 is
invariably less which is a characteristic of banded iron
formations. Other elements like Mn, Mg, Ca, Na, K, Ti
and P are present in very trace amount.
4. Beneficiation Study
BHQ and BHJ constitute around 35% of the iron ore re-
serve. Although India is blessed with large reserves of

J. K. MOHANTY ET AL. 1141
Table 3. Chemical analysis of iron ore samples.
Sl.No. SiO2 Al2O3 Fe2O3 MnO MgO CaO Na2O K2O TiO2 P
2O5 LOI* Sum
JKM1 75.76 1.25 21.38 0.02 0.04 0.14 0.07 0.01 0.03 0.06 2.25 101.01
JKM2 29.68 0.21 68.97 0.11 0.05 0.14 0.01 0.01 0.03 0.08 1.41 100.7
JKM3 1.52 0.71 86.25 0.22 0.06 0.24 0.01 0.01 0.04 0.33 11.12 100.51
JKM4 12.58 0.41 82.97 0.26 1.34 0.66 0.01 0.01 0.03 0.06 1.23 99.56
JKM5 1.23 0.59 96.81 0.03 0.01 0.02 0.01 0.02 0.04 1.53 100.29
JKM6 49.54 0.15 45.72 0.1 0.05 0.1 0.01 0 0.01 0.06 2.44 98.18
JKM7 1.34 1.30 84.62 0.22 0.10 0.30 0.01 0.03 0.46 0.30 11.91 100.59
JKM8 1.02 0.10 96.42 0.39 0.23 0.04 0.01 0.01 0.02 0.05 0 98.27
JKM9 28.49 0.17 70.10 0.02 0.03 0.04 0.02 0.01 0.04 0.06 2.09 101.07
JKM10 1.21 0.17 97.16 0.06 0.11 0.03 0.01 0.01 0.02 0.20 0.85 107.83
(
*LO I is do ne at 950˚C) (Sample No. same a s given in Table 1).
iron ore containing average grade around 58% Fe, the
performance of blast furnaces has been at lower levels in
comparison with developing countries. This is mainly
due to the presence of high levels of impurities such as
silica and alumina in the raw material contradicting to
blast furnace chemistry.
In order to increase the efficiency of blast furnace,
some of the issues relating to iron ores include chemical
composition of iron ore with low Fe content and high
Al:Si ratio, low strengt h, high tem perature breakdown, l ow
reducibility, low temperature softening and melting be-
haviour of iron ores, etc. Normally iron ores with 65% Fe
are desirable to achieve better productivity either in blast
furnace or direct reduction. The other impurities level
such as Na, K, S and P should be as low as possible. Alu -
mina and silica content should be within permissible limit
for better fluidity of slag. Due to decrease in good qu ality
iron ore, the Run-Of f Mine (ROM) ore with low Fe co n-
tent needs beneficiation to lower the impurities to im-
prove the strength of sinter and pellet quality. The phy-
sical, chemical and metallurgical properties of lumps,
sinters and pellets are important as they have a signifi-
cant impact on furnace performance.
Iron ore is being beneficiated all around the world to
meet the quality requirement of iron and steel industries.
However, each source of iron has its own peculiar mi-
neralogical characteristics and requires specific benefi-
ciation and metallurgical treatment to get the best pro-
duct out of it. The choice of beneficiation treatment de-
pends on the nature of the gangue present and its associ-
ation with the ore. Several techniques such as washing,
jigging, magnetic separation, gravity separation and flo-
tation are being employed to enhance the quality of the
iron ore. Washing, jigging and classification are being
carried out for the beneficiation of iron ores in India [6,7].
During washing and sizing of the ore, slimes with less
than 0.21 mm size are generated and discarded into the
tailing pond. It is estimated that around 10 million tones
of slimes are being generated every year during the
processing of hematite ore and lost as tailings containing
around 48% - 62% Fe. However, beneficiation and utili-
zation of these slimes still remains as a challenging task.
In this context, two low grade iron ore samples of si-
liceous nature (one BHJ and another BHQ) collected from
the iron ore formations of Orissa are taken up for their up
gradation of iron values by suitable beneficiation tech-
niques. One sample of BMQ having 40% Fe was up-
graded up to 63% Fe with a yield of 52%, while the re-
jection is around 17% Fe. Similarly, another sample of
BHQ having 35% Fe is upgraded to 61% Fe at 44% yield
with iron values of 16%Fe in the discarded tailings. A lot
of iron values are lost in the slimes also which indicates
the poor liberation of iron and silica in the feed material.
This is because of the fact that the silicate grains in mag-
netite/hematite are v ery fine grained as rev ealed by SEM.
Over grinding to get more iron minerals in liberated fo rm
results, more slime generation. Even though there is an
increase in the grade of iron in the product, the benefit of
this is being somewhat compensated by the energy con-
sumption during grinding and also in slime treatment.
5. Conclusion
Characterisation of iron ore is essential for its optimum
utilization. Demand for goo d gr ad e iron ore is on rise and
the reserve is limited. So utilization of low and medium
grade iron ores especially BHJ/BHQ is a necessity. Ef-
fective utilization of this type of iron ores can not be
achieved with out a proper assessment of the material in
respect of texture and mineralogy. This necessitates a

J. K. MOHANTY ET AL. 1142
detail ore characterisation which will help in under-
standing the mineralogical response during processing of
the ore. A combined approach of optical & electron mi-
croscopic study, XRD and Mossbauer & VSM study of
the iron ores from different iron formations (where huge
amounts of low to medium grade iron ores are available)
will give a better insight to the different mineralogical
attributes of the ore and their bearing on processing of
the ore and optimum utilization. The present study high-
lights the major minerals and their textural behaviour
such as relation between hematite and quartz and their
spatial distribution in the ore. It is observed that separa-
tion of macrobands is easy but to get a good grade of iron
concentrate from an ore having microbanding is difficult
due to intimate association of hematite and quartz on a
very fine scale. Presence of hematite in quartz and vice-
versa also affects the complete separation. So the inte-
grated mineralogical study is very important as it gives
an insight into the beneficiation process to be adopted
and its cost effectiveness.
6. Acknowledgements
The authors thank Director, CSIR-IMMT Bhubaneswar
for permission to publish this paper. This work is carried
out as a part of CSIR Network Program (NWP-31).
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