Journal of Minerals & Materials Characterization & Engineering, Vol. 8, No.2, pp 115-132, 2009
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115
Mineralogy and Geochemistry of A Low Grade Iron Ore Sample from
Bellary-Hospet Sector, India and Their Implications on Beneficiation
D. S. Rao*, T. V. Vijaya Kumar, S. Subba Rao, S. Prabhakar and G. Bhaskar Raju
National Metallurgical Laboratory - Madras Centre,
CSIR Madras Complex, Taramani, Chennai – 600 113
*Present address: M i n eralogy Department,
Institute of Miner a l s and Materials Technology,
Bhubaneswar – 751 013, Orissa, India
ABSTRACT
The gradual depletion of high-grade iron ores has necessitated the exploitation of low/off grade
iron ore reserves of India. The role of geochemical and mineralogical characterization is
paramount to arrive at the process flow sheet development for such complex ores. Detailed
studies were conducted on iron ores of Bellary-Hospet sector using microscope, XRD, TG, and
EPMA techniques. The results indicate that hematite is the major iron oxide mineral with minor
amounts of goethite, magnetite, martite and limonite with quartz and clay as major gangue.
There is no evidence of the presence of any iron silicate and iron carbonate minerals. Trace
amounts of pyrite were observed under the microscope and is the only iron sulphide phase.
Microscopic studies also indicated that most of the quartz grains are present as inclusions within
the hematite and magnetite grains. XRD studies revealed hematite as the major mineral with
subordinate amounts of goethite, quartz and kaolinite confirming to the microscopic findings.
Qualitative mapping and quantitative EPMA studies on these ores indicated the presence of
gibbsite as the only alumina bearing phase and apatite as phosphorous bearing mineral. Traces
of alumina, present as solid solution in the iron oxide minerals, has also contributed Al2O3 to the
ores. Electron microscopic studies revealed that gibbsite grains are in the size range of 10 to 50
microns and are intimately and intricately associated with the iron oxide phases. Major
elemental analyses of 47 representative iron ore samples of various types were analyzed to
deduce the source of silica and alumina’s contributing phases in the ore and their
interrelationships. The geochemistry data revealed negative correlation of Fe2O3 with silica and
alumina thus indicating there is no iron silicate phase as well as alumina contribution from iron

116 D.S. Rao, T.V.V. Kumar, S.S. Rao, S. Prabhakar and G.B. Raju Vol.8, No.2
oxide minerals in the form of solid solution is insignificant. Positive correlation of silica with
alumina indicates that the clay is the major contributing mineral for both the silica and alumina
phase and presence of gibbsite. The role of gangue minerals and the interrelationship of silica,
alumina and iron oxide, with reference to beneficiation are discussed. Jigs and heavy media
cyclones for this type of ores can be used but at the cost of poor yield because of complex nature
of alumina distribution. As long as alumina and silica mineralization is not too fine and the ore
composed of magnetite/hematite with coarse grained quartz, magnetic route is the most effective.
Since the quartz grains are too fine and their distribution is very complex for the Bellary-Hospet
sector ores, flotatio n i n gen er al and column flotation in particular seems to be more effective.
Key words: Iron o res, Mineralogy, EPMA, Geochemistry, Flotation
1. INTRODUCTION
Although India is having vast reserves of iron ore, lack of consistency with respect to Al2O3/SiO2
ratio makes these ores unsuitable to use directly in the metallurgical industries without prior
beneficiation. It has also been established that the adverse effects of high alumina to silica ratio
(ideally it should be < 1) is detrimental to blast furnace as well as sinter plant productivity.
Indian iron ores are being beneficiated by washing, scrubbing, hydrocycloning, gravity
separation and magnetic separation. During sizing and washing operations the enrichment with
respect to iron content is marginal and gangue reduction with particular reference to favorable
Al2O3/SiO2 is minimized. For better blast furnace productivity and slag flowability it is desirable
to have the alumina silica ratio at 1:1 in the blast furnace feed.
The quality specifications attached to the iron ores by steel makers is contrary to what nature has
provided. In other words, there exists a wide gap between the need and the reality. On an
average, 1.6 tonne of iron ore is required either as lumps or sinters to produce one tonne of hot
metal. The present day specifications of iron ore are
Physical Close sized lumps mostly (-40mm +10mm)
{However, fines (-10mm) are also used after sintering}.
Chemical High in Fe (65% Fe) content and low in alumina (preferably less than 2.5%)
Higher the iron content in the ore higher is the blast furnace productivity (as per the operating
practices, the increase of Fe concentration in the feed by 1% will increase the productivity by 1.5
to 2.5% and reduce the coke consumption by 0.8% to 1.2%). The reduction of alumina in blast

Vol.8, No.2 Mineralogy and Geochemistry of A Low Grade Iron Ore 117
furnace feed, reduces the rate of coke consumption, slag flowability and increases the digestion
of the metal in the blast furnace.
Mineralogical Mostly hematite (easy reducibility, narrow/low softening and melting
range as compared to magnetite)
Of course, the most important iron ore property to be used as feed in the blast furnace is the
consistency in all the above three qualities i.e. regularity of its physical, chemical as well as
mineralogical properties. Any variations in feed leads to unstable furnace operations as well as
inconsistent finished quality metal. In other words, the performance of steel plants in respect of
productivity, quality and cost depends largely on the above (physical, chemical and
mineralogical) characteristics. None of the Indian iron ore deposits can produce iron ores having
alumina below 2% preferred by blast furnaces. The reality is somewhat different. In some
deposits it may be possible to achieve alumina below 2% in lumps but fines usually analyze
alumina from 2.5 to 4.5% after crushing and washing. To overcome this disadvantage of Indian
iron ores, efforts have been directed to reduce alumina in iron ore lumps as well as fines so as to
bring down the levels of alumina in sinter to at least around 2.5% which is still higher than the
International standards of less than 2% alumina. However, lowering of alumina to the desired
levels by iron makers will lead to
¾ Increase in cost by adopting suitable ben efi ciation practices
¾ Incidence of fines and super fines i n the final stages
¾ Cost of sintering and pelletisation
In total, the Indian iron ores, in general, contain adverse alumina content and require
beneficiation to reduce the same in the ore for feeding to the blast furnace. Simple techniques
like crushing, scrubbing and washing of iron ores are being adopted to reduce alumina but these
techniques have their own inherent limitations and they are not effective to reduce alumina
below particular limits. This process limitation along with the demand by the steel plants for low
alumina iron ores encouraged researchers to characterize the ores in general and different modes
of associations of alumina in particular. In view of this, an attempt has been made to understand
the different modes of association of silica and alumina in iron ore sample form Bellary-Hospet
sector, Karnataka in t h e p re s e n t paper.
2. MINERALOGICAL CHARACTERISATION
2.1 Macroscopic Study
Considerable information can be drawn by macroscopic (unaided eye, with hand lens and/or with
the stereomicroscopy) study. For example, whether crystalline or amorphous nature of the ore;
soft or hard, or flaky ore or blue dust ore material, can be evaluated. Hard ore (generally contains
high iron and less alumina), as the name indicates, is hard and compact ore of steel grey in

118 D.S. Rao, T.V.V. Kumar, S.S. Rao, S. Prabhakar and G.B. Raju Vol.8, No.2
colour. Flaky ore (lean in iron content and rich in alumina) which is laminated type with
alternate bands of iron ore as well as gangue and is friable. Flaky ore and blue dust (generally
contains high iron and less alumina) are inherently soft and contain very high percentage of
natural fines. Soft ore (worst as compared to other types since they contain high alumina and
low iron) shows varying characteristics and is lumpy in nature. These physical characteristics
had great impact on the grinding and further processing as they contain varying amounts of silica
and alumina, which is considered to be harmful in the blast furnace.
Hence, the present iron ore sample from Bellary-Hospet sector was studied megascopically.
Study of the hand picked iron ore samples indicated that the ores can be grouped into three ore
types.
1. Hard ore: Hard ore as the n ame indicates is a hard and compact ore of steel grey colour.
2. Flakey ore: Flakey ore which is of laminated type occur as flakes. Flakey ore is inherently soft
and powdery in nature and contains very high percentage of fines.
3. Wad (soft ore): This is soft, light grey in colour, earthy, low specific gravity and non-
crystalline ore. Typically it contains mixtures of oxy-hydroxides of iron and silicate gangue
material and i s t h e w o rst of the three types and contains high alumina, silica and low iron.
In the hard ore hand specimens banding are observed both megascopically and microscopically
while in medium hard ores the laminations are vague due to intense leaching and presence of
innumerable voids (Figs.1-3). The hard ores usually show massive texture. Kaolinite occurs as
irregular patches and thin films. In rare instances wad is also observed along with the sample
(Fig.4).
2.2 Microscopic Study
Polish section study revealed that the as received iron ore sample contain hematite and goethite
as the major mineral with minor accessories of martite, maghemite while quartz and kaolinite
occurs as gangue minerals. Maghemite appears as skeletal patches. Rarely specular hematite is
also noticed in the hard ores. Many times minute crystals of silicate grains present as inclusions
with in the hematite and magnetite. Quartz appears as minute grain of different sizes (Figs.5 and
6). Such inclusions pose problem for liberation.

Vol.8, No.2 Mineralogy and Geochemistry of A Low Grade Iron Ore 119
Fig.1: Hematite occurs in the platy/banded structure showing bands of Silicates shown by
arrow). Stereomicroscopic photomicrograph.
Fig.2: Hematite shows banding of iron oxide minerals with silicates and porous structure.
Stereomicroscopic photomicrograph.
Fig.3: Patches of clay (white) and silicates are present within iron ore pieces.
Stereomicroscopic photomicrograph.
Fig.4: Rarely pieces of wad were present in the lumpy hand specimens. Stereomicroscopic
photomicrograph.
1 2
Clay
3
4

120 D.S. Rao, T.V.V. Kumar, S.S. Rao, S. Prabhakar and G.B. Raju Vol.8, No.2
Fig. 5: Magnetite (white at the centre) is also observed in the head sample. It can be observed
that there are numerous tiny inclusions of silicate gangue minerals within magnetite.
Reflected light Microscopic photomicrograph.
Fig.6: (a to d) Minute inclusions of silicate gangue (white grains in and b) present within the
iron ore minerals (black) in different shapes and sizes. Transmitted light Microscopy.
a
b
c
d
S
ili
cate
Iron oxide
minerals

Vol.8, No.2 Mineralogy and Geochemistry of A Low Grade Iron Ore 121
2.3 XRD Studies
XRD analysis of the as received head sample revealed (Fig.7 and Table 1) that the major iron
bearing opaque minerals are hematite (JCPDS No.33-664) followed by goethite (JCPDS No.29-
713). The other silicate gangue minerals identified are quartz (SiO2, JCPDS No.33-1161) and
kaolinite {Al2Si2O5(OH)4, JCPDS No.14-0164}.
Head sample XRD analysis
Fig. 7: XRD pattern of the as received powder sample
Phases identified
are Hematite,
Goethite
Quartz and
Kaolinite
in order of
abundance

122 D.S. Rao, T.V.V. Kumar, S.S. Rao, S. Prabhakar and G.B. Raju Vol.8, No.2
Table 1: Phase identification of the XRD peaks
No Angle Counts D space Rel I Phases identified
1 21.18 742 4.867 13 Goethite
2 23.12 749 4.464 13 Kaolinite
3 24.70 830 4.182 14 Goethite / Kaolinite
4 28.12 224 3.682 39 Hematite
5 28.96 921 3.577 16 Goethite / Kaolinite
6 31.10 758 3.337 13 Goethite/Quartz/Kaolinite
7 38.72 575 2.698 100 Hematite / Goethite
8 40.96 621 2.557 11 Goethite / Kaolinite
9 41.64 322 2.516 56 Hematite / Goethite
10 42.84 661 2.449 11 Goethite/Quartz/Kaolinite
11 46.00 633 2.289 11 Hematite/Goethite/Quartz/Kaolinite
12 47.88 187 2.204 33 Hematite / Goethite / Kaolinite
13 51.14 591 2.072 10 Hematite / Goethite / Kaolinite
14 58.20 197 1.839 34 Hematite/Goethite/Quartz/Kaolinite
15 63.78 245 1.693 43 Hematite/Goethite/Quartz/Kaolinite
16 68.10 889 1.598 15 Hematite/Goethite/Quartz/Kaolinite
17 74.22 104 1.483 18 Hematite / Goethite /
18 75.96 147 1.454 26 Hematite / Goethite / Quartz
19 83.08 610 1.349 11 Hematite
20 86.06 971 1.311 17 Hematite
21 90.68 620 1.258 11 Hematite / Quartz
22 95.16 527 1.212 9 Hematite / Quartz
23 97.66 576 1.188 10 Hematite / Quartz

Vol.8, No.2 Mineralogy and Geochemistry of A Low Grade Iron Ore 123
2.4 TG Analysis
The weight loss below 200oC of the TG plot (Fig.8) indicates loss of surfacial water or the
adsorbed water of the sample. The dehydration (loss of structural water) of goethite takes place
around 400oC while that of kaolinite takes place between 400oC to 850oC and that for hematite is
beyond 850oC. The TG analysis and the weight loss observed correlates well with that of the
chemical analysis results.
Fig.8: TG plots of the as received sample
2.5 EPMA Studies
A few samples were studied under the electron microscope to decipher the gibbsite. It was
observed that minute inclusions of gibbsite (Fig.9), in the range of 10 to 50 microns, occur
within the iron oxide minerals. They are very intricately and intimately present along with the
iron ore minerals the liberation of which is very difficult. Quantitative EPMA analysis of iron
ore minerals along with their associated phases indicated that alumina is present in more or less
all the phases but the highest amount is observed in the limonite as solid solution within the
0200 400 600 8001000
-3.2
-2.8
-2.4
-2.0
-1.6
-1.2
-0.8
-0.4
0.0
SampleHead
Fe 60.14
SiO26.76
Al2O33.55
LOI 3.15
TG Plot of head samp le Iron ore
15 oC/Min .
Head sample
% W eigh t lo ss
Temperature (oC)

124 D.S. Rao, T.V.V. Kumar, S.S. Rao, S. Prabhakar and G.B. Raju Vol.8, No.2
structure/lattice of the iron oxide phases. Analysis number 15 is apatite, 16 is clay and 17 is a
gibbsite phase (Table 2).
Fig.9: Electron microscopic mapping of an iron ore sample showing presence of gibbsite
Mineral along with iron oxide minerals
BSE
Al
Si Fe
Fig.9 Fig.9
Fig.9 Fig.9

Vol.8, No.2 Mineralogy and Geochemistry of A Low Grade Iron Ore 125
Table 2: EPMA analysis of the various iron oxides along with other associated phases
3. GEOCHEMICAL CHARACTERIZATION
A of total of forty seven hand picked samples were collected and chemically analyzed. All
samples were analyzed for Fe2O3, SiO2, Al2O3 and LOI which attests to the above varieties of
ores. Diagnostic elemental assemblages of major and minor elemental association can be used
to distinguish the varieties of iron ores used in the present case. Hence, a total of 49 samples
were drawn (hand picked) and analyzed to decipher the chemical nature of the samples used as
the feed material for the test purpose. All these samples were analyzed for Fe2O3, SiO2, Al2O3
and LOI (Table 3). Salient features of the geochemical studies are as follows
1. From the analysis results it is inferred that these iron ores have wide variation in the Fe2O3,
SiO2 and Al2O3 content. From the chemical analysis it can be concluded that there are three
varieties of iron ore samples viz. iron ore, banded hematite quartzite and wad. That means the
physical ore types categorized above are chemically distinguishable in general by its iron, silica
Al2O3 SiO2 P
2O5 Fe2O3 Total
Hematite
1 0.39 0.00 0.00 94.97 95.36
2 0.48 1.16 0.06 95.12 96.82
3 1.34 0.70 0.10 91.35 93.48
4 1.07 1.06 0.04 92.51 94.68
5 0.68 0.00 0.01 95.21 95.90
Goethite
6 4.67 0.00 0.10 76.01 80.78
7 3.98 0.00 0.11 76.91 81.01
8 2.23 0.00 0.60 85.55 88.38
9 2.70 1.80 0.09 82.82 87.42
Limonite
10 2.68 1.07 0.05 60.99 64.79
11 7.59 0.00 0.26 70.68 78.53
12 6.18 0.68 0.14 71.32 78.31
13 1.10 0.36 0.00 68.95 70.41
14 8.48 0.17 0.14 57.72 66.52
Other phases
15 0.00 1.01 44.5 0.01 45.51
16 18.52 69.07 0.00 0.02 87.62
17 59.39 1.45 0.02 0.08 60.94

126 D.S. Rao, T.V.V. Kumar, S.S. Rao, S. Prabhakar and G.B. Raju Vol.8, No.2
and alumina content. The hard varieties of iron ores contain higher iron, lower silica as well as
alumina while the wad varieties contain lower iron and higher amounts of silica and alumina.
2. It is also inferred that these iron ore samples are totally devoid of sulfide (except pyrite) and
carbonate minerals which is indicated by its low LOI value.
3. The percentage of banded hematite quartzite and wad samples in the feed material varies in
the range between 5 to 10%.
4. To confirm the above observation on varieties of iron ores, specific gravity studies were
conducted (by pycnometer) on all the above 47 hand picked samples. It was observed that
specific gravity of the samples decrease with decrease in the Fe2O3 (Fig.10) content confirming
to the geochemical as well as mineralogical studies that other varieties of ore samples like wad
and banded hematite quartzite are present. It may be noteworthy that during sampling banded
hematite quartzite (BHQ) was observed as micro-bands of silicate in the iron ore samples as
shown in the hand specimen photographs.
Regression analysis revealed that the iron oxide (Fe2O3) is having a strong negative correlation
with silica and alumina (Fig.11 and 12). Silica has a positive correlation with alumina (Figs.13).
The negative correlation of iron with silica as well as alumina indicates that iron is present as
hematite as well as goethite while silica and alumina are present as completely different phases
like quartz and kaolinite. Similar trend is also observed in the case of iron vs. (SiO2 +Al2O3)
0 1020304050
2.0
2.5
3.0
3.5
4.0
4.5
5.0
5.5 Fig.10 r = - 0.88
Sp e c ific g r avity
SiO2 + Al2O3

Vol.8, No.2 Mineralogy and Geochemistry of A Low Grade Iron Ore 127
plotting (Fig.14) which clearly suggests that the silica and alumina exists as kaolinite. The weak
positive correlation of silica with alumina indicates that they are related in a phase kaolinite over
and above silica being present as quartz.
5060708090 100
-2
0
2
4
6
8
10
12
14
16
18
20 Fig.12 r = - 0.70
% Al2O3
% Fe2O3
50 60 70 80 90100
0
10
20
30
40 Fig.11 r = -0.9 3
% SiO2
% Fe2O3

128 D.S. Rao, T.V.V. Kumar, S.S. Rao, S. Prabhakar and G.B. Raju Vol.8, No.2
0 10203040
-2
0
2
4
6
8
10
12
14
16
18
20 Fig.13 r = + 0.42
% AL2O3
% SiO2
50 60 70 80 90100
0
10
20
30
40
50 Fig.14r = - 0.81
SiO2+Al2O3
Fe2O3

Vol.8, No.2 Mineralogy and Geochemistry of A Low Grade Iron Ore 129
Table 3: Bulk chemical composition of the hand picked samples
Sample
ID %Total Fe Fe2O3 %SiO2 %Al2O3 %LOI Total Specific gravity
1 43.54 62.26 13.04 14.75 9.45 99.50 3.431
2 62.17 88.90 2.40 1.41 6.78 99.49 4.580
3 40.93 58.52 19.94 10.44 10.59 99.49 2.450
4 62.65 89.58 2.33 1.56 6.02 99.49 4.611
5 63.03 90.13 1.66 0.40 7.36 99.55 4.199
6 61.79 88.35 3.50 2.83 4.81 99.49 4.545
7 65.87 94.19 1.48 1.88 1.94 99.49 5.220
8 66.08 94.49 1.38 0.72 2.90 99.49 4.914
9 64.26 91.89 1.06 0.15 6.40 99.50 4.650
10 65.42 93.55 2.35 1.68 1.92 99.50 5.140
11 66.47 95.05 1.08 0.31 3.06 99.50 4.910
12 62.38 89.20 1.48 0.32 8.50 99.50 4.020
13 65.31 93.39 1.19 0.45 4.46 99.49 4.770
14 65.59 93.79 1.49 1.02 3.20 99.50 4.874
15 66.10 94.52 1.19 0.53 3.25 99.49 4.731
16 49.34 70.55 26.15 1.46 1.33 99.49 3.179
17 66.24 94.72 1.50 0.42 2.85 99.49 4.977
18 65.82 94.12 1.45 0.31 3.62 99.50 4.490
19 50.88 72.75 23.82 1.24 1.68 99.49 3.579
20 60.21 86.10 4.64 4.34 4.42 99.50 4.501
21 66.10 94.52 1.55 0.73 2.69 99.49 4.931
22 39.91 57.07 15.39 18.03 9.01 99.50 3.495
23 43.10 61.63 30.48 3.65 3.84 99.60 3.682
24 65.38 93.49 2.39 1.93 1.78 99.59 4.591
25 44.79 64.05 30.80 3.85 0.90 99.60 3.628
26 65.61 93.82 2.52 1.57 1.69 99.60 4.865
27 65.09 93.08 1.17 1.31 4.04 99.60 4.675
28 39.46 56.43 37.04 5.06 1.07 99.60 3.020
29 43.76 62.58 32.41 3.79 0.83 99.61 3.461
30 34.45 49.26 39.98 6.80 2.13 98.17 3.110
31 51.61 73.80 21.20 3.25 1.35 99.60 3.990
32 62.19 88.93 4.64 1.60 4.43 99.60 4.343
33 48.10 68.78 26.79 3.37 0.66 99.60 3.680
34 64.60 92.38 2.10 1.78 3.34 99.60 4.552
35 65.90 94.24 1.19 1.35 2.82 99.60 4.850
36 62.86 89.89 1.28 1.40 7.03 99.60 4.327

130 D.S. Rao, T.V.V. Kumar, S.S. Rao, S. Prabhakar and G.B. Raju Vol.8, No.2
Table 3: Bulk chemical composition of the hand picked samples (continuing)
Sample
ID
%Total
Fe Fe2O3 %SiO2 %Al2O3 %LOI Total Specific
gravity
37 64.83 92.71 1.40 1.38 4.12 99.61 4.650
38 65.22 93.26 2.73 1.34 2.27 99.60 4.730
39 62.58 89.49 2.58 1.94 5.59 99.60 4.522
40 62.38 89.20 5.37 3.01 2.01 99.59 4.663
41 66.28 94.78 1.70 1.43 1.69 99.60 4.884
42 49.58 70.90 24.23 3.37 1.15 99.65 3.700
43 64.02 91.55 3.87 1.50 2.68 99.60 4.534
44 52.76 75.45 15.98 4.09 4.08 99.60 4.580
45 45.10 64.49 29.52 3.99 1.60 99.60 3.682
46 64.43 92.13 3.04 1.73 2.70 99.60 4.832
47 46.03 65.82 28.06 3.61 2.10 99.59 3.505
4. CONCLUSIONS
Mineralogical studies by microscope indicated that hematite is the major iron oxide mineral
with minor amounts of goethite, magnetite, martite and limonite with quartz and clay (kaolinite)
as major gangue. Iron ore deposits of Orissa, India have also similar mineralogical associations
(Roy and Das, 2008). There is no evidence of the presence of any iron silicate and iron carbonate
minerals. Trace amounts of pyrite were observed under the microscope and is the only iron
sulphide phase in these samples. Microscopic studies also indicated that most of the quartz grains
are present as inclusions within the hematite and magnetite grains. XRD studies revealed
hematite as the major minerals with subordinate amounts of goethite, quartz and kaolinite
confirming the microscopic findings. Qualitative mapping and quantitative EPMA studies on
these ores indicated the presence of gibbsite as the only alumina bearing phase. Traces of
alumina, present as solid solution in the iron oxide minerals, has also contributed to the ores.
Electron microscopic studies revealed that gibbsite grains are in the size range of 10 to 50
microns and are intimately and intricately present along with the iron oxide phases.
Geochemistry data revealed negative correlation of Fe2O3 with silica and alumina thus
indicating there is no iron silicate phase as well as alumina contribution from iron oxide minerals
in the form of solid solution is insignificant. Positive correlation of silica with alumina indicates
that the clay is the major contributing mineral for both the silica and alumina phase and presence
of gibbsite. The role of gangue minerals and the interrelationship of silica, alumina and iron
oxide, is of paramount importance in the flow sheet development of any ore. Jigs and heavy

Vol.8, No.2 Mineralogy and Geochemistry of A Low Grade Iron Ore 131
media cyclones for this types of ores can be used but at the cost of poor yield because of
complex nature of alumina distribution. As long as alumina and silica mineralization is not too
fine and composed of magnetite/hematite with coarse grained quartz magnetic route is most
effective. Similar ore types were studied for their beneficiation aspects but even after magnetic
separation also the ore could not yield good grade and recovery hence flotation was tried and a
better grade as well as recovery was achieved (Vijaya Kumar et al., 2005a, b; Mishra et al.,
2007). Since the quartz grains are too fine and their distribution is very complex for the Bellary-
Hospet sector ores, flotation in general and column flotation in particular seems to be more
effective. Since in these ores silica is present as quartz and alumina is mostly contributed by
kaolinite, which is also a silicate, as these are present as very fine grains, hence chances are there
that flotation especia l l y re v erse flotation may work better.
Feed characterization is equally important with all other steps in flow sheet development. It can
be argued that without proper understanding of the feed it may be impossible, to end with a
successful process. Understanding the mineralogical as well as geochemical nature of ore also
prevents unnecessary test works and the loss of precious tim e. A detail characterization of the ore
needs the eye of a mineralogist and mind of a mineral processing engineer.
ACKNOWLEDGEMENTS
The authors are thankful to the Director, National Metallurgical Laboratory, Jamshedpur for his
valuable guidance, encouragement and permission to publish this work. The authors are indebted
to M/s. JSW, Bellary and Indian Bureau of Mines, Nagpur for chemical and EPMA analysis
respectively.
REFERENCES
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Bhaskar Raju, G., (2005a) Beneficiation of iron ore fines by conventional flotation, flotation
column and dual extraction column- a pilot scale study. Powder Handling and Process., 17(2),
pp.88– 93.
2. Vijaya Kumar, T. V., Rao, D. S., Subba Rao, S., Prabhakar, S., More, P., and Bhaskar Raju,
G., (2005b) Semi-commercial scale studies using flotation column and dual extraction column
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