a comparative mineralogical and geochemical characterisation of iron ores from two indian...

A comparative mineralogical and geochemicalcharacterisation of iron ores from two IndianPrecambrian deposits and Krivoy rog deposit,Ukraine: implications for the upgrading of leangrade ore

S. Roy*1, A. Das1 and A. S. Venkatesh2

Iron ores from two important Precambrian belts in India are studied in detail. The first of these is

the Jilling-Langalota deposit, hosted by banded iron formations along with generations of shales,

tuffs belonging to Iron Ore Group of Eastern India and is hosted in the Singhbhum-North Orissa

Craton. The second group of ores is from the Chitradurga basin in Eastern Dharwar Craton,

Southern India. These form part of the Archaean greenstone belts and show a typical oxide–

carbonate–sulphide association. The Jilling-Langalota deposit contains considerable amounts of

blue dust that is absent in the Chitradurga deposit. Comparisons are made between the Indian

iron ores and those of the Krivoy Rog province of the Central Ukrainian Shield. The Indian iron ores

are relatively richer in Fe and contain higher amounts of alumina and phosphorous compared with

those of the Krivoy Rog deposit. The Indian iron ore samples contain porous and friable oxides

and hydroxides of iron with kaolinite, gibbsite and quartz. In contrast, the ores from Krivoy Rog are

massive with negligible clay and a higher quartz content leading to very low alumina and very

high silica contents in the ores and slime. The Indian ores and slimes are manganiferous in nature

with high alumina, which is deleterious to processing and is due to the presence of intercalated

tuffaceous shales and clay. The Eastern Indian iron ore deposits could have been formed due to

enrichment of the primary ore by gradual removal of silica. It is believed that the massive ores

result from direct precipitation while powdery blue dust is formed owing to circulating fluids, which

leach away the silica from the protore. The host rock is exhalatic banded iron formation and the

ubiquitous presence of intercalated tuffaceous shales point towards a genesis that could have

involved Fe leaching from sea floor volcanogenic rocks. The nature of these ores along with the

parting shale is responsible for production of large amounts of alumina rich slime during mining

and handling. The detailed mineralogical characterisation studies aided by X-ray diffraction,

scanning electron microscopy—energy dispersive spectroscopy, physical parameters and

chemical characteristics have indicated the presence of various mineral phases and established

the nature of iron-bearing and gangue assemblages of the bulk ores and slime samples from the

three iron ore deposits. These in turn are useful in understanding the amenability of the ores and

slimes for beneficiation and waste utilisation.

Keywords: Banded iron formation, Mineralogical characterisation, Low grade iron ores, Iron ore slime, Archaean Iron Ore Group, India

IntroductionImportant iron ore deposits occur in eastern, central andsouthern India in the states of Jharkhand, Orissa,Karnataka, Chhattisgarh and Goa. The Eastern Indianiron ores belong to Archaean Iron Ore Group (IOG)while the Southern Indian iron ores belong to the

1MNP Division, National Metallurgical Laboratory, Jamshedpur 831 007,India2Department of Applied Geology, Indian School of Mines University,Dhanbad 826 004, India

*Corresponding authors, [email protected]

� 2008 Institute of Materials, Minerals and Mining and The AusIMMPublished by Maney on behalf of the Institute and The AusIMMReceived 29 April 2008; accepted 30 September 2008DOI 10.1179/174327508X375602 Applied Earth Science (Trans. Inst. Min. Metall. B) 2008 VOL 117 NO 3 125

Archaean Dharwar Supergroup. The iron ores ofEastern India are relatively higher in quality andquantity containing both hematite (10 052 MT) andmagnetite (3408 MT) varieties.42 The haematite oredeposits are mainly confined to the states ofJharkhand, Orissa, Karnataka, Goa and Chattisgarh.Magnetite, limonitic and lateritic deposits are confinedto the states of Karnataka and Andhra Pradesh.Broadly, the iron ore types are hard, flaky/friable,lateritic and blue dust or powdery varieties. Indian ironore is relatively rich in Fe and contains higher amountsof alumina and phosphorous compared with the othermajor deposits of the world. With increasing worldwidedemand for iron ore by China, coupled with other newacquisitions by major steel making companies, iron oreproducing countries have attempted to increase theiriron ore production by taking steps to utilise low gradeiron ores, fines and slimes.

The generation of fines is undesirable but unavoidableat the same time due to the mechanised processes ofmining, processing and handling of bulk material. Ironore is no exception; especially the laminated and lateriticores of India that are quite soft and friable in nature. Inthe form of slimes, these fines are relatively low gradeand cannot be utilised directly in a blast furnace. Atpresent, they are generally dumped into the tailingponds due to lack of proper processing technology.However, such dumping may cause serious environ-mental hazards8 over a prolonged period and hence,there is an increasing need for mineralogical character-isation in order to see whether it may be possible tobeneficiate blue dust, fines and slimes.

Most of the iron ore slimes are very fine in nature(,150 mm) and proper characterisation is very diffi-cult.9,12,13,18,22,24 Most of the reported characterisationstudies in these cases have been concerned more withthe chemical composition rather than with the miner-alogy, grain morphology, liberation studies, particlesize distribution, etc. Hence, mineralogical andgeochemical characterisation is important beforebeneficiation.10,23,32,40

Indian iron ore is characteristically different from ironores of other parts of the world and these differences arereflected in slime characteristics as well. A higherpercentage of alumina is usually associated with Indianiron ore slimes.19 Beneficiation and/or utilisation ofslimes are still not practiced on an industrial scale inIndia. However, the volume of generated slimes is largeand the grade is often reasonably high. Hence, there areopportunities for utilisation of these slimes from bothwaste utilisation and value addition points of view andthereby safeguarding the environment. Moreover, theuse of sinter and pellet feed in blast furnaces around theworld have increased manifold over recent years. Inprinciple, slimes are ideal for generating the material forpelletisation and they can also be used for preparation ofsinter feed after microballing. Slime processing, there-fore, may open up a great opportunity for utilisation ofthese slimes that are primarily a waste material atpresent.

The soft, laminated, friable and lateritic ores of Indiacontain large amounts of alumina and it has now beenestablished both by laboratory and plant trials thatalumina has an adverse effect on sinter and pelletproperties. The reduction degradation behaviour of the

sinter can be improved considerably by lowering itsalumina and silica contents and increasing the ironcontent. The reducibility index of the pellets would alsoincrease with the lowering of alumina content. Thus,beneficiating the slimes to remove the gangue mineralsand enhance its grade is a prospective proposition.However, without a thorough mineralogical character-isation, such processing may not be very efficient.

In the present work, three different iron ores andassociated slimes, having different chemical and miner-alogical characteristics, are taken up for characterisationstudies. These ores and slimes possess different ironcontents and variable quantities of gangue minerals. Anattempt has been made in this study to compare twoimportant Indian deposits that occur in differentgeological environments, namely, the Jilling-Langalotadeposit belonging to the IOG and the Chitradurga oresbelonging to the Dharwar Supergroup in India. Acomparison is also made with the Krivoy Rog depositsof Ukranian Sheild. The principal aim is to miner-alogically characterise the bulk ores and slimes fromthese deposits with a view to test their amenability forbeneficiation and value addition.

Detailed studies of mineralogy, grain-morphology,particle size distribution, liberation and chemical char-acteristics have been conducted for three deposits usingmicroscopy, scanning electron microscopy–energy dis-persive spectroscopy (SEM–EDS), image analyses, X-ray diffraction (XRD) and heavy liquid separationstudies. These provide key information about the natureof the valuable and deleterious constituents in thedifferent ores and slimes.

Geological aspects and controls ofmineralisation of the three iron oredepositsIron ore deposits occur predominantly in the Eastern,Central and Southern regions of India. The EasternIndian iron ores are confined to the Singhbhum- NorthOrissa Craton within the Singhbhum, Keonjhar, Bonai,Mayurbhanj and Cuttack districts in a horseshoe shapedsynclinorium (Fig. 1). Important mining centres arelocated at Noamundi, Chiria, Gorumahisani, Joda,Gua, Bolani, Barsua, Barbil-Barajamda (Jilling-Langalota), Kiriburu, Tomka and Daitari. In CentralIndia, Bailadilla in Bastar and Dalli-Rajhara in Durgare important deposits of Chhattisgarh and MadhyaPradesh. Bababudhan, Chitradurga, Kummangundi,Donimalai, Kumarswami, Kodachadri and Kotabareare important deposits of Karnataka state that are partof the Dharwar Supergroup in Southern India. Richblue dust is found in Goan deposits and in some of theeastern Indian deposits including the present study area.

For the Indian iron ores, the host rock is bandedhaematite jasper (BHJ) or banded haematite quartzite(BHQ) that is formed as a result of chemical precipita-tion in partially enclosed sedimentary basins during longperiods of geological quiescence.2,5,6 High grade iron oredeposits formed owing to enrichment of these forma-tions by gradual removal of silica.4,18 It is possible thatthe massive ores are the result of direct precipitationwhile powdery blue dust is formed owing to circulatingwaters developed in palaeo-hydrological channels,which leached away the silica from massive ores. The

Roy et al. Comparative mineralogical and geochemical characterisation of iron ores

126 Applied Earth Science (Trans. Inst. Min. Metall. B) 2008 VOL 117 NO 3

principal iron minerals are oxides (haematite andmagnetite) and hydroxides (goethite and limonite) inJilling-Langalota while the Chitradurga deposit has apredominantly oxide–sulphide–carbonate associationindicating differences in the environment of deposition.

Jilling-Langalota iron ore deposit, Eastern India

Lithological controls and nature of mineralisation

The iron ores of Eastern India are deposited in a broadhorse-shoe shaped synclinorium basin which has two

1 Map shows distribution of banded iron formation (BIF) in Singhbhum-Orissa region20


Applied Earth Science (Trans. Inst. Min. Metall. B) 2008 VOL 117 NO 3 127

limbs in which the most of the iron ores are deposited.The entire sequence of iron ore deposition is called IronOre Group (IOG) within the Archaean Singhbhum-North Orissa Craton.14 The chrono-stratigraphic suc-cession is given in Table 1. The weakly metamorphosedvolcano-sedimentary sequence of rocks, occurring inand around the area, belong to the iron ore series ofearly Precambrian age14 and forms part of the easternlimb exhibiting a westerly dip of the northerly plungingasymmetric synclinorium. In addition to banded ironformation (BIF), the IOG also contains other rock unitssuch as two generations of shales and tuffs that underlieor are interlayered with the BIF. The IOG rocks arebound within unconformities dated at 3?2 to 2?9 Ma(Ref. 35) and generally consist of inter-bedded andinter-bordered shales and altered volcanic tuffs whichare generally associated with rich deposits of iron oresthat are capped by ferruginous laterite.

The Jilling-Langalota iron ore deposit within the IOGis one of the best iron ore exposures hosted byPrecambrian BIF in India. There are four ore bodiesin the Jilling-Langalota area, namely, Jilling, Gang-aigora, Langalota and Jajang (Fig. 2a). The ore bodiesare bedded and lensoidal with variable dimensions.Those at Langalota are the biggest, consisting of 73% ofthe total bulk of the ore deposit (Fig. 2b). The orebodieshave thickness ranging from 2?2 to 66?7 m up to amaximum depth of 76?90 m and the total reserves ofJilling-Langalota deposits are 61?7 million tonnes.29

Most of the ore bodies are mined for iron using opencast methods of mining until the lower shales areencountered. Since multiple generations of shales occurrhythmically as markers within the IOG, the possibilityof iron ore below the lower shale can not be ruled out.

The deposits as whole have undergone extensiveleaching where the palaeo-hydrological channels have,in many cases, partially or wholly removed the silicafrom the banded iron ores, leading to the developmentof laminated, porous, biscuity and blue dust types ofiron ores.11 The BIFs of adjoining region within the IOGexhibit primary depositional and digenetic features, both

in BHJ as well as the associated iron ore deposits. Ingeneral, shallow water environment of deposition in aregion proximal to the shoreline with a rather steeppaleoslope of the shelf has been surmised.28 The leachedsoft, laminated and powdery iron ores lead to theformation of large amount of slimes and fines duringmining and processing.20

Bulk iron ore samples were collected from severalcontinuous outcrops of the Jilling Langlota iron oredeposits. A total of 55 ore samples were collected. Thedetails of the sample locations are given in Fig 2a.Samples of hard massive ore (6 samples), flaky friableore (11 samples), blue dust (5 samples), soft laminatedore (12 samples), lateritic ore/canga (15 samples) andmanganiferous ores (6 samples) are collected fromdifferent freshly exposed outcrops from Jilling iron oredeposits (Fig 2a). The slime was obtained by washing ofthe composite ore (soft laminated ore, flaky-friable oreand lateritic ore) and wet sieving at 150 mm.

Structural controls

The area has been affected by various phases ofdeformation events that, in turn, marked by differentmetamorphic events, produced their impacts on thelithostratigraphic units in different scales.35 The generaltrends of rocks of the IOG are North-South withvariation between N10uW–S10uE to N10uE–S10uW anddipping towards West to East due to warping and folds.These rocks have been subjected to a number of foldmovements (Fig. 3a) with the axis of major movementbeing along N–S and the superimposition of variousdeformation events complicates the structure of the area.This is evident from the radiating pattern of dips andplunges as observed in BHJ rock types. The ore body islaid down in a broad refolded synform with N–S axesplunging both southerly and northerly. Broadly, theJilling and Gangaigora ore bodies have a southerlyplunge of 5–10u whereas the northern part of Langalotaore body has a northerly plunge while the southern parthas southerly plunge 5–10u. The ore body broadens outtowards the south. Pinching and swelling of the ore body

Table 1 Generalised chronostratigraphic succession of the Singhbhum-North Orissa Craton34

Newer Dolerite dykes and sills y(1600–950) MaMayurbhanj granite y2100 MaGabbro-anorthosite-ultramafics y(2100–2200) Ma

UnconformityJagannathpur lava Dhanjori SimlipalMalangtoli lava lavas (y2300 Ma) Dhanjori Group

Quartzite-ConglomeratePelitic and arenaceous metasediments with maficsills (approximately 2300–2400 Ma)

Singhbhum Group

UnconformitySinghbhum Granite (Phase III) y3.1 GaMafic lava, tuff, acid volcanicsTuffaceous shale, BHJ and BHQ with iron ores(study area)

Iron ore

ferruginous chert, local dolomite and sandstone Group

Singhbhum granite Nilgiri Granite(Phase I and II) y3.3 Ga Bonai Granite

Folding and metamorphism of OMG and OMTG y(3.4–3.5) GaOlder metamorphic tonalite gneisses (OMTG) 3.775 GaOlder metamorphic group (OMG)Pelitic-schists, quartzite y4.0 GaPara-amphibolite, Ortho-amphibolite



2 a geological map of Jilling-Langalota iron ore deposit and b cross-section along the line AB’, showing different units

of the deposit



is due to the superimposition of several generations offolds.

Three sets of vertical to sub vertical joints and two setsof sub-horizontal joints are distinctly developed(Fig. 3b). The ores are of different variations, massive,laminated, and lateritic and pass laterally into oneanother (Fig. 3c). The average dip is about 35 to 40utowards west. The laminated hard ore bands representthe enriched parts of the BIF and these bands are muchcrumpled, minutely folded and broken by tiny faults.Slump structures are common in such ore bands. Thesoft biscuity ores are generated by leaching of silica fromBIF and exhibit heavy shattering, breaking and crum-pling (Fig. 3d). The lateritic ores generally form asuperficial capping that is horizontal over the main orebody.

Classification of the Jilling-Langalota ores

Ore textures are complex due to the effects ofmetamorphism, deformation, alteration and supergeneprocesses and secondary mineral formation in theJilling-Langalota ores is observed. Some of the micro-structural and textural features that are observed inthese areas include microfolds, brecciated zones, micro-faults and microbands. Clout7 adopted ore texturalclassification based on Australian iron ores as:

(i) dense martite/haematite(ii) microplaty haematite

(iii) martite-goethite(iv) goethite-martite(v) dense haematite/martite/hydrohaematite

(vi) dense martite-goethite

(vii) dense goethitemartite(viii) microplaty haematite-goethite

(ix) ochreous goethite

(x) vitreous goethite.The Indian iron ores have been classified mineralogicallybased on detailed ore microscopy, SEM–EDS and XRDas banded haematite jasper/banded haematite quartzite,massive hard laminated ore (lumpy), soft laminated ore,flaky friable ore (biscuity), blue dust, lateritic ore, conga(recemented ore), goethitic ore and manganiferous ore.The details are given below.

Banded haematite jasper (BHJ)

This rock consists of alternate bands of haematite andjasper as mesobands and microbands (Figs. 4a and 5a). Atplaces, martitisation of magnetite to haematite is visibleand martite, which is pseudomorphous after magnetite, inmost cases, retains the shape of the original magnetite.

Massive hard laminated ore

Haematite grains are fine grained and tightly packedforming a compact mass (Fig. 4b). They consist ofspecularitic haematite with minor silica in the interstitialspaces (Fig. 5c). Martite is common in this ore type,retaining the relict shape of precursor magnetite. Martitegrains are disseminated within primary haematite grains.Goethite is rare and is occasionally found in theproximity of pore spaces and along the weak planarsurfaces of hematititic laminae. There are differentmodels regarding the origin of these high grade iron

a rocks have been subjected to a number of deformation events; b three sets of joints developed in massive hard lami-nated iron ore; c different variations of ores such as massive hard laminated, soft laminated, blue dust, lateritic pass lat-erally into one another; d the soft biscuity ores show extensive shattering, breaking and crumpling

3 Structural disturbances within the Jilling-Langalota deposit



ores. They include deep seated hydrothermal,41 synge-netic and diagenetic16 and supergene models.3 Highgrade ore types occur in wide varieties that includemassive ore, hard laminated ore, soft laminated ore,biscuity ore and powdery ore and are altered with varieddegree of porosity and development of microplatyhaematite (Fig. 6). The population of nanometre tomicrometre scale haematite plates is interpreted torepresent various stages of nucleation, crystallisationand progressive growth of haematite from the primary

ore-forming fluid in areas that were once iron-richcarbonates or silicates in the BIF.33 Al-bearing mineralssuch as kaolinite and gibbsite occur as surface coatingand as thin bands. Finer sizes contain a few free shales,laterite and quartz patches.

Soft laminated ore

In this type of ore, individual lamellae measure from a fewmillimetres to centimetres in thickness (Fig. 5d) and the

a banded hematite jasper; b massive hard laminated ore; c biscuity ore; d blue dust; e flaky friable ore; f canga ore; glateritic ore; h manganiferous ore

4 Different types of iron ores from Jilling-Langalota iron ore deposit



ore is highly porous and fragile (Fig. 4c). The principle oreand gangue minerals are the same as that of massivevariety but there are many voids between the lamellae,which at times are filled with secondary haematite in

colloidal form. Micro-platy haematite is interlinked like anetwork of minerals between the pores (Fig. 5e). Besideshaematite, the other major iron-bearing phase is goethite.Goethite occurs as colloform bands and vein fillingmaterial within voids and cavities and the voids andcavities are also filled with kaolinite and gibbsite.

Blue dust

Blue dust occurs as minor pockets and the patches arerandomly oriented within the major ore type as pockets.The ore is steel grey in colour and occurs either asrandom patches generally along major fractures or jointsor near the top of the ore horizon as thin but persistentbeds perhaps generated through paleo-hydrologicalchannels. The blue dust is mostly a fine powderymaterial consisting of fine flakes of haematite and otherimpurities such as shale/clay and silica (Fig. 4d).

Flaky/friable ores

The flaky variety ores are brownish to steel greycoloured enclosing flakes of haematite containingsecondary goethite as cementing material along thebedding planes in addition to kaoline and shaly materialpreserving the original texture of parent BIF (Fig. 5f).Most of the friable ore bands can easily be dug from afresh working face because of their friable nature. This

a micro-fracture and micro-faulting planes are filled with clay; b microbands of haematite and jasper in BIF; c specularitichaematite tightly packed forming compact mass in massive hard laminated ore; d lamellae in soft laminated iron ore; emicro-platy haematite with pores in between filled with clay; f goethite and kaolinite along the weaker planes and voidsin friable ore; g limonitic clays and goethite in lateritic ore; h pyrolusite occurs as interlayred with cryptomelane andgoethite; i pyrolusite occur as colloform banded form

5 Photomicrographs of iron ore samples of Jilling-Langalota under stereomicroscope

6 Thin microplaty haematite of maximum dimension y3 mm

grown along the pore space as observed under SEM



variety generally underlies soft ore and at places isassociated with ochre (Fig. 4e).

Lateritic and canga ores

Canga is a surfacial deposit blanketing the ore at placesand is mostly composed of mixed fragments of hard orethat are both rounded as well as angular, and also rarepieces of BHJ cemented in laterite and limonitic matrix(Fig. 4f). Lateritic ore occurs just below the Canga bedand is highly spongy and porous in nature (Fig. 4g).Lateritic ore is dull earthy in colour with limonitic red,yellow and dull white patches. Goethite is foundabundantly in the laterite ore but its content decreaseswith depth. Lateritisation is quite intense and extendsgenerally to a depth of 8–12 m from the surface. Thecontact between laterite and Canga is usually sharp.Limonitic clays are prominent along the bands ofiron ores indicating replacement of the bands (Fig. 5g).Clay-rich laterites are also present. The laterites showbotryoidal and pisoidal structures which containgoethite and limonite, frequently exhibiting box-workstructures.

Manganiferous ore

Manganese ore minerals, such as pyrolusite, cryptome-lane and manganite, are found to be associated withsome iron ores of the above types except BIF. Thismakes them manganiferous at places (Fig. 4h).However, the overall Mn content is very low.

Chitradurga iron ores, dharwar supergroup,southern indiaIn Chitradurga iron ore, banded haematite and magne-tite quartzite are common rock types that are frequentlyencountered in Archaean greenstone belts of Karnataka(Fig. 7). The iron ores of Chitradurga are of low gradecompared to those of Jilling-Langalota. The mostimportant iron ore deposits/prospects belong to theBababudan and Chitradurga Groups within theDharwar Craton.25,27 In Chitradurga, the BIF is notdirectly associated with volcanism as in the Bababudantype, but form a component of a sedimentary successionstarting with mixed-pebble (polymictic) conglomerate

followed by a limestone-manganese-iron formationmarker horizon and extensive development of grey-wacke in the deeper parts of the basin.26 The primaryiron ore occurs as alternating layers of iron oxideminerals (haematite and magnetite) and quartzite withthe thickness of the layers varying between 0?1 to25 mm. In places, the protore (comprising 30–50%Fe)has been enriched by residual concentration processes to60–65%Fe.26

The samples studied are collected from the freshoutcrop. A total of twenty three iron ore samples arecollected. The details of sample locations are given inFig 7. Proper care was taken to collect the best possiblefresh samples. The slime sample is obtained by washingthe composite ore and wet sieving at 150 mm.

Krivoy Rog iron ore deposit, UkraineIn the Eastern European states, about two-thirds of thetotal iron ores come from the 2?2 Ga Superior-typeKrivoy Rog Supergroup in the Donetz Basin ofUkraine.21 The Krivoy Rog iron ore province in thecentral part of the Ukrainian Shield is about 120 kmlong and comprises a 2 to 10 km wide basin within thesub-meridional striking Krivoy Rog-Kremenchug zone(Fig. 8). This zone is folded and thrusted and separatesthe westerly volcano-sedimentary Ingul-Inguletsk pro-vince from the easterly-situated Dnjiepropetrovsk block.The Dnjiepropetrovsk block is derived from greenstonebelts that were stabilised in the late Archaean.43 Theevolution of the iron ore basin could have been initiatedfrom the compression of the crust and the consequentdeformations lead to the Krivoy Rog structure.15 Thegeneration of the Krivoy Rog BIF took place in fourmajor phases, namely, hydrothermal/sedimentary stage,tectonometamorphic stage, post-metamorphic stage andweathering stage. The shales and shaly BIF weredeposed and supplied by clastic and terrigenous inputswithin the shelf during the primary sedimentation stagewith most of the cherts originating in deep areas.43

Twelve iron ore samples, are collected (Fig. 8). Theslime sample for the present study was obtained bywashing the bulk ore and wet sieving at 150 mm.

7 Geological map of Chitradurga Iron ore deposits36–38



Mineralogical characterisation of ironore samplesThe detailed microscopic studies indicated thepresence of various mineral phases. X-ray diffractionanalysis shows that the iron ore minerals present in

Jilling-Langalota deposit include oxy-hydroxy formslike martite, haematite, and goethite (Fig. 9a).Haematite is mainly laminated and specularitic in nature(Fig. 5c), whereas goethite mostly occurs as vug-fillingand replacement types (Fig. 5f). Detailed mineralogicaland textural characterisation of different types of iron

8 Geological map of Krivoy Rog iron ore deposit, Ukraine17



ores from this region shows that most of the softlaminated, lateritic and friable ores are relatively lowgrade carrying various proportions of impurities. X-raydiffraction analysis of the associated clay material showsthat it is mainly composed of kaolinite and gibbsite(Fig. 9b). The soft laminated lateritic ores are porousand contain friable oxides and hydroxides of iron alongwith kaolinite, gibbsite and quartz. The occurrence ofkaolinite, gibbsite and hydrated oxides along the cavitiesand weaker planes of haematite has been observed(Fig. 5b, e, f and g) and the friable nature and highalumina contents within the iron ores are attributed tothe secondary phases. The nature of these ores alongwith the parting shale is responsible for the productionof large amounts of alumina-rich slime during miningand handling operations.

Manganese minerals, albeit in low abundance, havealso been observed and include pyrolusite, cryptomelaneand manganite. Pyrolusite mainly occurs as irregularpatches associated with cryptomelane and goethite.Coarse euhedral grains of pyrolusite showing tabularto prismatic habit with well defined twinning andcleavage are found in some massive varieties of ore(Fig. 5h). Pyrolusite also occurs as vug-filling in goethiteand cryptomelane (Fig. 5h). Cryptomelane mainlyoccurs as colloform bands (Fig. 5i). X-ray diffractiondata of haematite, goethite, kaolinite and gibbsite arepresented in Fig. 9 and are also shown in Table 2.

Chitradurga iron ores contain haematite as the majoriron-bearing mineral phase with kaolinite as thedominant gangue in most of the ore samples. Mostof the primary laminations have been replaced by

a haematite; b kaolinite, gibbsite, haematite and goethite9 X-ray diffraction pattern of iron ore samples from Jilling-Langalota (Hm – haematite; Go – goethite; Gb – gibbsite; K –

kaolinite)



secondary iron minerals as specularite-flakes (Fig. 10a).Generally, the grain-size of haematite varies in differentbands, though it remains relatively constant within asingle band. The other major iron-bearing phase isgoethite which occurs as colloform bands and vein fillingwithin the voids (Fig. 10b). Some pieces are porous withcavities and in many instances, these cavities are filledwith kaolinite. Some of the ore fragments have under-gone extensive weathering producing ochreous goethiteand kaolinite.

The ore is generally soft and friable in nature, whichusually leads to slime generation during ore handling.Some of the samples are martitised (Fig. 10c) with relictmagnetite grains present in the ore samples (Fig. 10c).This implies that oxygen from infiltration water is

incorporated into the magnetite lattice during themartite formation.1

Manganiferous minerals have also been observedalong with iron ore minerals. Pyrolusite occurs as acavity filling mineral (Fig. 10d). However, as with theJilling-Langalota samples, the overall presence ofmanganese minerals is low in these ores. The presenceof magnetite, haematite, goethite, kaolinite and quartz isalso supported by XRD data (Fig. 11) of the contrast inthe XRD and mineralogical observations of the threeiron ores and slimes is given in Table 2.

The iron ore samples from Krivoy Rog are char-acterised by alternating bands/ laminations of ironminerals and silica (Fig. 12a). The thickness of indivi-dual bands varies from less than 1 mm to over 5 mm.

a microplaty haematite with kaolinite precipitated in void spaces/cavities; b colloform goethite precipitated in voids; crelict magnetite in martitised grain around which goethite is deposited in the voids; d pyrolusite precipitated in voidspaces/cavities

10 Photomicrographs of Chitradurga iron ore samples under stereomicroscope

Table 2 X-ray diffraction data on iron ores and slimes

Mineral phases

Iron ores and slimes

Jilling Chitradurga Ukraine

Iron-bearingminerals

Hematite occurs as majormineral and goethite as minoriron-bearing mineral, magnetitenot found

Hematite occurs as majormineral and goethite as minoriron-bearing mineral, relictmagnetite found

Hematite occurs as majormineral and goethite as minoriron-bearing mineral, relictmagnetite found

Manganeseminerals

Pyrolusite and cryptomelane. Pyrolusite and braunite Absent

Gangue mineralphases

Quartz, kaolinite and gibbsiteare the major gangue phases.

Quartz and kaolinite are themajor gangue phases.

Quartz occurs in abundance as majormineral phases, kaolinite is not traceable



The bands are generally parallel and continuous.However, at places, ‘pinching and swelling’ structures,disruptions or minor folds are also recorded.

Microscopic studies reveal that the bands consist ofrelict magnetite, martite, haematite, goethite and quartz asalso observed using XRD (Fig. 13). While the concentra-tion of iron minerals in an ‘iron-rich band’ is more orless uniform, in a ‘silica-rich band’ it is highly erratic.Haematite/martite/magnetite occurs in three modes:

(i) as independent coarser grains [(.100 mm)(Fig. 12b)]

(ii) as intergrowths/inclusions within quartz[(.20 mm) (Fig. 12c)]

(iii) as fine disseminations [(20 mm) (Fig. 12d)].

In some bands, the grain size becomes too fine (y11 mm).The gangue assemblages include quartz (as major gangue)and clay that occur in the inter-granular grain boundariesor cavities of iron minerals along with goethite. Incidenceof clay is increased at places where the ore has becomeporous due to weathering and become altered.

Mineralogical, physical and geochemicalcharacterisation of iron ore slimesThe characterisation of the iron ore slimes includeparticle size analyses, chemical analyses, specific gravitymeasurement, detailed microscopic examinations, SEM–EDS study, image analysis and heavy liquid separation.The details of analytical results are given in thefollowing sections.

Particle size measurementsParticle size measurements of three iron ore slimes wereconducted using Shimadzu SACP3, centrifugal particlesize analyser. In order to collect samples in each sizerange, sieving of iron ore slime of each sample wascarried out using the Vibratory Laboratory Sieve Shaker‘analysette3’. Size distributions of the slime samples arepresented in Table 3. Microprecision sieves are used forseparation of 250 mm sized particles. It is seen from thesize distribution curves (Fig. 14) that all three slimes are

a kaolinite; b haematite, magnetite and goethite11 X-ray diffraction pattern of Chitradurga iron ore samples with identified phases (Hm – haematite; Mt – magnetite; G –

goethite; K – kaolinite; Q – quartz)



extremely fine in nature. Substantial amounts of theslimes are below 20 mm in size range. In the case ofJilling-Langalota sample, the weight percentage ofthe size fraction less than 20 mm is 71?22%.30 In theChitradurga31 and Krivoy Rog iron ore slimes, thecorresponding values are 54?46 and 55?84% respectively.

Chemical compositional characteristics ofslimesChemical composition of various size fractions is givenin Table 4. It has been observed that z20 mmfractions are richer in Fe content in Jilling-Langalotaand Chitradurga iron ore slimes. In the case of theJilling slime sample, the z20 mm fraction contains48?92%Fe,30 while this size class of Chitradurga ironore slime contains 54?58%Fe.31 In Krivoy Rog slime,the iron is almost equally distributed in all sizes. Silicadistribution is also uniform at about 54% in all sizeclasses. Very little alumina has been observed in theUkrainian sample which is therefore, amenable forbeneficiation.

In Indian iron ore slimes, besides the silica, alumina isalso a major impurity. Alumina is deleterious for blastfurnace operations and it is observed to be concentratedin the finer size classes. The alumina contents are 16?72and 10?11% in the 220 mm size class in Jilling andChitradurga samples, respectively while the Krivoy Rogiron ore slime contains only 2?27%Al2O3 in the 220 mmfraction. Most of the iron is concentrated in the coarser

sizes in the Jilling and Chitradurga slimes whereas in theKrivoy Rog slime, it is evenly distributed. Therefore, it isevident that a de-sliming operation to remove theultrafine fraction would improve the grade in the twoIndian Ores. However, since the distribution of iron andsilica is uniform over the size fractions for the KrivoyRog sample, a de-sliming classification in a hydrocy-clone for this sample will not be useful.

Specific gravity measurementsThe specific gravity of the three iron ore slimes wasmeasured using a picnometer by the standard method.The size-wise specific gravity data of the three iron oreslimes are given in Table 5. The specific gravity ofChitradurga iron ore slime is more than that of the othertwo slimes indicating that significant amounts of iron-bearing minerals are present in this slime.

SEM studiesMicromorphological and mineralogical characterisationstudies are carried out using scanning electron micro-scopy attached with EDS microanalyser (JSM 840 A/EDS). This study allowed the differentiation of variousmineral phases, grain sizes, micromorphological fea-tures, textural features, interlocking behaviour ofindividual particles aided by elemental composition ofthe ores and slimes. Back-scattered SEM images withEDS of the three slime samples are presented in Fig. 15.It can be seen from the EDS graphs, that in Jilling and

a alternating bands/laminations of iron minerals and silica; b haematite/martite/magnetite occurs as independent coarsergrains; c haematite occurs as intergrowths/inclusions within quartz; d fine disseminated haematite in quartz

12 Photomicrographs of Ukraine iron ore sample under stereomicroscope (Hm – haematite; Go – goethite; Qtz – quartz;

Mt – martite; V – void/cavity)



Chitradurga slime, the Si and Al are the majorimpurities, where as in Krivoy Rog iron ore slime, Alis negligible and Si content is higher.

The SEM–EDS are also carried out for iron-bearingparticles that appear to be liberated under the microscopeand the results are shown in Fig. 15. It can be seen that inthe Jilling iron ore slime, iron-bearing minerals (Fig. 16a)

are very spongy and porous with rough surfaces,indicating some degree of weathering. Gravity separationis somewhat sluggish during beneficiation due to theporous and spongy nature of the slime and its corre-spondingly lower density. Aluminium is common inweathered environment, resulting in Al substitution inmost of the iron oxides.37

a quartz, goethite and haematite; b quartz; c haematite and magnetite13 X-ray diffraction pattern of iron ore from Krivoy Rog deposit with different phases



Quartz and clay are the main gangue phases in theJilling and Chitradurga slimes. Scanning electronmicroscopy and EDS of clay particles of these twoslimes are given in Fig. 17. Most of the clays (kaoliniteand gibbsite) are ferrugenous. The Jilling sample alsocontains traces of phosphorus (Fig. 17a). The quartz,kaolinite and gibbsite in Jilling iron ore slime36 andquartz, kaolinite in Chitradurga iron ore slime mainlycontribute towards the high Al2O3 and SiO2 content inthe slimes.

In the Chitradurga iron ore slime, the iron-bearingparticles (Fig. 16b) contain relatively low amounts ofalumina and silica. In Krivoy Rog iron ore slime, theiron particles (Fig. 16c) are not porous and are relativelycompact with smooth surfaces. They contain very lowpercentages of impurities. The observations are tabu-lated in Table 6. The X-ray spectra of liberated iron-bearing particle (Fig. 16a and b) from the Jilling andChitradurga iron ore slimes indicate that they containimpurities along with some Mn. Although the Mncontent is very low, it would remain in the concentrateproduct even after beneficiation.

Image analysis and microscopic studiesImage analysis and microscopic examination of differentsize fractions of the ore and slime samples are taken upfor volumetric analysis of various mineral phases andliberation studies. These studies are carried out bytaking representative sample of each size fraction of theslime. The size fraction less than 10 mm is not consideredowing to difficulty in mounting. Each of these sizefractions are carefully mounted using bakelite powder ina mounting press. More than 30 images for each sizeclass are processed for maximum phase separation andlater they are carefully analysed. High resolution imagesare taken to ensure that the differences between silicatesand iron-bearing phases are identifiable in the images.

Visual inspection of images reveal that in the Jillingiron ore slime, haematite is the most abundant phaseand the other iron-bearing phase is goethite havingwhite and light grey features, respectively. Goethiteoccurs in very low quantities (Fig. 18). Quartz and clay

are the main gangue phases, and they can be easilydistinguished from iron-bearing phases, having dull greyand black features respectively. Haematite is the mostabundant phase in the Chitradurga iron ore slime withsome goethite and relict magnetite at places. Quartz andclay are the main gangue phases. In the Krivoy Rog ironore slime, haematite is the most abundant iron-bearingphase along with some goethite. Quartz is the maingangue phase with a negligible quantity of clay in thisslime.

Volumetric distribution of different phases in eachsize fraction is estimated using Grey ThresholdTechnique39 and is presented in Table 7.

Table 3 Distribution of particles in different size fractions

Mean size, mm

Jilling slime Chitradurga slime Krivoy Rog slime

wt-% Cumulative undersize, % wt-% Cumulative undersize, % wt-% Cumulative undersize, %

150 1.64 100 5.35 100 1.16 100105 4.30 98.36 8.17 94.66 2.80 98.9875 4.94 94.06 4.18 86.49 2.08 96.0463 1.78 89.12 3.85 82.31 4.95 93.9650 16.12 87.34 24.00 78.46 33.17 89.0120 10.10 71.22 12.88 54.46 30.02 55.8410 61.12 61.12 41.54 41.54 25.82 25.82

14 Graphical representation of size distribution

Table 4 Chemical analyses of the three iron ore slimes

Size, mm

Jilling (assay%) Chitradurga (assay%) Krivoy Rog (assay%)

Fe Al2O3 SiO2 Fe Al2O3 SiO2 Fe Al2O3 SiO2

2150z50 52.70 8.12 5.62 56.28 4.43 7.26 29.07 1.04 54.82250z20 45.92 9.08 14.06 53.03 6.12 8.57 28.43 1.38 55.10220 33.40 16.72 22.61 45.91 10.11 12.07 28.12 2.27 54.68Head 37.86 14.40 19.08 49.86 7.93 10.19 28.32 1.84 54.83

Table 5 Specific gravity values of three different iron oreslimes

Size, mm

Specific gravity of iron ore slimes


2150z50 3.45 3.74 2.90250z20 3.32 3.56 2.86220 3.11 3.33 2.87Head 3.18 3.47 2.87



Photomicrographs of the 2150z75 mm size class of allthe three slimes are presented in Fig. 18. It can be seenfrom this figure that in the Jilling and Chitradurga ironore slimes, besides quartz, clay also occurs in significantquantity. The Ukraine slime has abundant quartz incomparison to the other two slimes.

Data related to interlocking character of iron particleswith gangue phases and percentage of gangue liberatedin each size fraction are also estimated (Table 8).

In the Jilling iron ore slime, clay phases are presenteither as free liberated particles or interlocked with

haematite. Liberation analysis shows that in the coarserfractions, haematite is highly interlocked with clay(Fig. 19). The percentage of haematite-clay interlockingdecreases with decreasing particle size. However, thevolumetric percentage of free haematite decreases with adecrease in particle size (Fig. 20) due to the increase inliberated gangues in the finer size fractions. Therefore,achieving a high purity concentrate from this slime bybeneficiation may be difficult.

The percentage of liberated clay is also increasing witha decrease in the relative size as shown in Fig. 21. The

a Jilling slime; b Chitradurga slime; c Krivoy Rog slime15 Photomicrographs (SEM) of head samples with EDS



a Jilling; b Chitradurga; c Krivoy Rog16 Photomicrographs (SEM) with EDS of iron-bearing particles of slimes

Table 6 Scanning electron microscopy and energy dispersive spectroscopy data

Mineral phases

Iron ores and slimes


Iron-bearingminerals

Very porous and spongy. Containsome Al and Si in liberated particlesmajor mineral

It contains some Al andSi in liberated particles

Almost regular smooth surfaceand compact grains. Relatively lowAl and Si in liberated particles

Manganeseminerals

Having some manganese content Having some manganesecontent

No manganese, etc.

Gangue minerals Kaolinite and gibbsite occur asferruginous with traces of P. Quartzparticles have negligible Fe

Kaolinite occurs as ferruginouswith traces of P. Quartz particleshave negligible Fe

Kaolinite is absent Quartz is theonly gangue mineral



maximum percentage of liberated clay is found to be88?65% in the 230 to z10 mm size fraction (Table 8).Most of the quartz particles occur as free liberatedgrains. However, some interlocking behaviour isobserved in the coarser size fractions (Fig. 19). Asshown in Fig. 21, the percentage of liberated quartz isalso very high and it increases with decreasing particlesize. The maximum percentage of liberated quartz is99?97% in the 230z10 mm size fraction in this slime.

In the Chitradurga iron ore slime, the degree of clay-haematite interlocking is lower than that in the Jilling

sample (Fig. 19). Percentages of liberated clay andquartz increase with decreasing particle size (Fig. 21)in this slime as well. Maximum gangue liberation valuesare obtained in the 230z10 mm size fraction, making itless problematic to treat during beneficiation.

In the Krivoy Rog iron ore slime, free liberatedhematite also increases with decreasing particle size(Fig. 19). However, the slime is very rich in quartz andespecially the finer size fractions contain maximumliberated quartz (Fig. 21). The coarser fractions havea high degree of interlocking between quartz and

a Jilling; b Chitradurga17 Photomicrograph (SEM) with EDS of liberated clay particles of slimes31

a Jilling; b Chitradurga; c Krivoy Rog18 Photomicrographs of three different iron ore slimes of size fractions 2150z75 mm with phases identified in each

sample (FHt – free haematite; FQ – free quartz; FC – free clay; LHt – locked haematite)



Table 7 Volumetric distribution of different phases in different size fractions

Mineral phases

Volume per cent in different size fractions

2150z75 mm 275z50 mm 250z30 mm 230z10 mm

Jilling iron ore slimeHematitezgoethite 68.32 64.52 56.15 41.20Quartz 11.35 13.83 22.73 34.36Kaolinite 20.33 21.65 21.12 24.44Chitradurga iron ore slimeHematitezgoethite 73.48 71.16 69.45 62.39Quartz 14.25 15.51 16.49 20.73Kaolinite 12.27 13.33 14.06 16.88Ukraine iron ore slimeHematitezgoethite 30.48 30.49 30.27 29.66Quartz 69.52 69.51 69.73 70.34

Table 8 Microscopic data on the liberation characters of the three iron ore slimes

Mineral phases

Volume per cent in different size fractions

2150z75 mm 275z50 mm 250z30 mm 230z10 mm

Jilling iron ore slimeFree hematite/goethite 56.47 51.63 47.86 40.07Free quartz 9.35 12.43 18.12 26.07Free clay 15.12 18.78 19.15 23.21Locked hematitezclay 17.64 16.12 14.15 10.61Locked hematitezquartz 1.42 1.04 0.72 0.04% of clay liberated 68.18 76.90 81.86 88.65% of quartz liberated 96.34 97.95 99.97 99.97

Chitradurga iron ore slimeFree hematite/goethite 66.13 64.93 60.91 58.76Free quartz 11.23 11.97 13.76 16.62Free clay 10.34 11.83 15.03 18.43Locked hematitezclay 10.43 10.05 8.65 05.85Locked hematitezquartz 1.87 1.22 1.65 0.34% of clay liberated 73.91 79.69 86.12 92.65% of quartz liberated 96.00 97.52 97.66 99.59

Ukraine iron ore slimeFree hematite 24.21 25.52 32.65 40.63Free quartz 46.94 47.32 49.57 54.25Locked hematitezquartz 28.92 27.14 17.78 5.12% of quartz liberated 82.26 85.32 91.77 98.15

a haematite with clay interlocked; b haematite with quartz interlocked19 Liberation graphs of three iron ore slimes



iron-bearing particles but the finer size fractions showalmost complete liberation. The maximum percentage ofliberated quartz is 98?15% in the 230z10 mm sizefraction in this slime sample.

Heavy liquid separationCharacterisation is also performed using sink-floatstudies in heavy liquid to assess the quality of the ironore slime samples. Pure bromoform (sp. gr. 2?81) wasused to quantify the heavy (sp. gr. .2?81) and light (sp.gr. ,2?81) content of the slime samples. The sink floatdata are presented in Table 9. It may be seen from thistable that in the Chitradurga slime, the percentage ofheavy minerals is 89?6%; while in the Jilling and theKrivoy Rog slimes this is 65?3 and 26?1% respectively.Heavy mineral content within the Indian samplesgenerally decreased with decreasing particle size andmost of the light minerals are concentrated in the lowersize range. However, for the Krivoy Rog slime the heavyminerals are somewhat evenly distributed in all the sizeclasses below 75 mm. Although the heavy mineralcontent of the z75 mm fraction is much higher (about60%), the weight percentage of material above 75 mm isnegligible (about 4%).

Discussion and conclusionsMineralogical and geochemical characterisation studieshave been carried out on three important Precambrianiron ore deposits; two of them occur in differentgeological settings from India and the other is in theUkrainian Shield. In the Indian iron ore samples,haematite mainly occurs as specularite with inter-granular micro-pore spaces and martitisation is acommon feature. Goethite is abundant and occurs assecondary colloform texture in cavities along the weakerbedding planes. Such inter-granular pore spaces andvoids along the weaker bedding plane make thehaematite and goethite friable. These friable particlesbreak down during mining and processing and accountfor the high iron content of the slime. Most of the bulkore samples contain numerous cavities. These cavitiesare mainly filled with clay in the form of kaolinite andgibbsite. Kaolinite and gibbsite are very friable andeasily concentrate into the smallest size fractions duringmining and processing operations.

In contrast, in the iron ores from Krivoy Rog,haematite and goethite are closely packed with quartz

a free haematite; b free clay; c free quartz20 Liberation graph of three iron ore slimes

a percentage of clay liberated; b percentage of quartz liberated21 Liberation graph of three iron ore slimes



forming a complex interlocking texture. These charac-teristics persist in the slime, leading to substantialinterlocking of haematite-clay/goethite-clay in theIndian iron ore slimes and interlocked haematite-quartz/goethite-quartz in the Krivoy Rog slime.

In the fine size fractions of the Indian slimes, thedegree of clay interlocking is relatively low. This couldallow for a relatively easy removal of clay by de-slimingclassification. Some amount of interlocking has beenobserved in the coarser size fractions indicating that aminimum percentage of gangue would invariably bepresent in the beneficiation concentrate. They may alsooccur as middling product during the beneficiationoperations of these slimes.

In the Chitradurga iron ore, manganese minerals suchas pyrolusite and braunite occur in association withhaematite and goethite and the manganese mineralassemblages are also seen in this slime. The Mn-mineralassemblages remain in the final concentrate owing totheir high density and their close association with iron-bearing minerals indicating that they cannot be sepa-rated during processing.

In the Indian iron ore slimes, besides the silica,alumina is also a major impurity. These impurities aremainly concentrated in the finer size classes. Thealumina content is 16?72 and 10?11% in the 220 mmsize in Jilling and Chitradurga samples respectively,while it is relatively lower in Krivoy Rog iron ore slime(2?27%) in the 220 mm fraction.

Porous and spongy nature of the iron-bearingparticles indicates that the Jilling sample has undergonesignificant degree of weathering. Due to the presence ofporosity, its density is lower and beneficiation throughgravity separation would require special attention.Special attention would also be required in separationprocesses based on surface characteristics. The compact,smooth and nonporous surface of the iron-bearingparticles in the Krivoy Rog sample along with itsnegligible clay content would render this slime perfectlyamenable to simple gravity separation.

Variable degrees of Al and Si substitution of Fe in thehaematite in the Jilling and Chitradurga samplesindicate variable degrees of alteration due to weathering.Negligible weathering of haematite in the Krivoy Rogslime is evident from the EDS studies. Presence of Fe inliberated clay particles of the Indian samples indicatethat this is of ferrugenous variety. The associationbetween phosphorous and clay indicates that beneficia-tion for removal of Al would remove the P as well.

Although a minor component, the presence of Mn inChitradurga ores would add value to the slime whenbeneficiated.

In the iron ores from Krivoy Rog, quartz is the maingangue phase along with negligible quantity of clay. As aresult, the ore is very massive and does not generatesignificant amounts of slime. The Krivoy Rog slime hasa uniform distribution of gangue and valuable mineralsin all size classes and the degree of haematite-clayinterlocking is negligible in this slime. The highpercentage of liberated quartz and liberated iron-bearingparticles occur in the lower size fractions suggesting thatde-sliming classification would not be useful for KrivoyRog slimes.

Acknowledgement

Financial assistance in the form of CSIR fellowship to S.Roy is gratefully acknowledged. The authors thank theeditor and the two reviewers for their comments whichsignificantly improved the manuscript.

References1. V. Belykh, E. Dunai and I. Lugovaya: ‘Physicochemical formation

conditions of banded iron formations and high-grade iron ores in

the region of the Kursk Magnetic Anomaly: Evidence from isotopic

data’, Geol. Ore Deposits, 2007, 49, (2), 147–159.

2. N. J. Beukes and C. Klein: ‘Models for iron-formation deposition

in Proterozoic biosphere’, 147–151; 1992, New York, Cambridge

University Press.

3. N. J. Beukes, H. Dorland, J. Gutzmer, M. Nedachi and H.

Ohmoto: ‘Tropical laterites, life on land, and the history of

atmospheric oxygen in the Paleoproterozoic’, Geology, 2002, 30,

491–494.

4. N. J. Beukes, J. Gutzmer and J. Mukhopadhyay: ‘The geology and

genesis of high-grade haematite iron ore deposits’, Appl. Earth Sci.,

2003, 112, 18–25.

5. L. O. Castro: ‘Genesis of banded iron-formations’, Econ. Geol.,

1994, 89, 1384–1397.

6. K. L. Chakraborty and T. Majumder: ‘Geological aspects of the

banded iron formation of Bihar and Orissa’, J. Geol. Soc. Ind.,

1986, 28, 109–133.

7. J. M. F. Clout: ‘Upgrading processes in BIF-derived iron ore

deposits: implication for ore genesis and downstream mineral

processing’, Appl. Earth Sci., 2003, 112, 89–95.

8. J. M. F. Clout: ‘Iron formation-hosted iron ores in the Hamersley

Province of Western Australia’, Appl. Earth Sci., 2006, 15, (4), 115–

125.

9. B. Das, S. Prakash, B. K. Mohapatra, S. K. Bhaumik and K. S.

Narasimhan: ‘Beneficiation of iron ore slimes using hydrocyclone’,

Miner. Metall. Process., 1992, 9, (2), 101–103.

10. B. Das, B. K. Mohapatra, P. S. R. Reddy and S. Das:

‘Characterization and beneficiation of iron ore slimes for further

processing’, Powder Handl. Process., 1995, 7, (1), 41–44.

Table 9 Heavy liquid (sp. gr. 2?81) sink-float data of iron ore slimes

Size, mm

Jilling slime Chitradurga slime Ukraine slime

Sink,wt-%

Sink,wt-%

wt-%(w.r.t.o)*

Sink,wt-%

Sink,wt-%

wt-%(w.r.t.o)*

Sink,wt-%

Sink,wt-%

wt-%(w.r.t.o.)*

2150z105 1.6 82.3 1.4 5.4 91.3 4.8 1.2 58.5 0.72105z75 4.4 72.5 3.1 8.2 93.2 7.6 2.8 59.9 1.7275z63 4.9 69.6 4.4 4.2 88.3 3.7 2.1 29.4 0.8263z50 1.8 63.2 1.1 3.9 87.3 3.4 5.0 26.7 1.3250z20 16.1 65.6 10.6 24.0 92.0 22.1 33.2 20.4 7.9220z10 10.1 62.3 6.4 12.8 92.9 12.0 30.0 26.4 7.9210 61.1 62.7 38.3 41.5 86.6 36.0 25.8 26.6 6.9

Total 100 – 65.3 100 – 89.6 100 – 26.1

*With respect to original.



11. G. A. Gross: ‘Industrial and genetic models for iron ore in iron

formations: in mineral deposit modelling’, Geol. Assoc. Canada,

Special paper 1993, 40, 151–170.

12. B. Gujraj, J. P. Sharma, A. Baldawa, S. C. D. Arora, N. Prasad

and A. K. Biswas: ‘Dispersion–flocculation studies on hematite-

clay systems’, IJMP, 1983, 11, 285–302.

13. K. Hanumantha Rao and K. S. Narasimhan: ‘Selective flocculation

applied to Barsua iron ore tailings’, IJMP, 1985, 14, 285–67–75.

14. H. C. Jones: ‘The iron ore deposits of Bihar and Orissa’, Geol. Surv.

Ind. Mem., 1934, 63, 357.

15. G. I. Kalyaev, E. B. Glvatsky and G. K. Dimitrov: ‘Paleotectonics

and stucture of the earth crust of the Precambrian iron ore province

of the Ukraine’, 271; 1984, Kiev, Naukova Dumka.

16. H. F. King: ‘The rocks speak, Australasian Institute of Mining and

Metallurgy, Monograph, Melbourne’, Aus IMM, 1989, 15, 1–36.

17. D. A. Kulik and V. V. Pokalyuk: ‘The balance of solid matter in

sedimentary cycles of iron accumulation in the Krivorozhsky

Basin: lithology and ore deposits’, J. Geol., 1990, 2, 36–49.

18. D. F. Lascelles: ‘Genesis of the Koolyanobbing iron ore deposits,

Yilgarn Province, WA, Australia’, Appl. Earth Sci., 2007, 116, (2),

86–93.

19. S. Mahiuddin, S. Bandopadhyay and J. N. Baruah: ‘A study on the

beneficiation of Indian iron ore fines and slime using chemical

additives’, IJMP, 1989, 11, 285–302.

20. T. Majumder, A. S. Venkatesh, V. Kumar and R. K. Upadhyay:

‘Mineralogical characterization of iron ores from Eastern India

with special emphasis on beneficiation of iron ore fines’, Proc. Iron

Ore 2005 Int. Conf., Fremantle, WA, Australia, September 2005,

Trans Aus IMM special publication series no. 8/2005, 227–231.

21. K. C. Mishra: ‘Understanding mineral deposits’, 839; 2000,

Dordrecht, Kluwer Academic Publishers.

22. P. Pradip: ‘Beneficiation of alumina-rich Indian iron-ore slimes’,

Metall. Mater. Process., 1994, 63, 179–194.

23. S. Prakash, B. Das, B. K. Mohapatra and R. Venugopal: ‘Recovery

of iron values from iron ore slimes by selective magnetic coating’,

Separat. Sci. Technol., 2000, 35, (16), 2651–2662.

24. N. Prasad, M. A. Ponomarev, S. K. Mukherjee, P. K. Sengupta, P.

K. Roy and S. K. Gupta: ‘Introduction of new technologies for

beneficiation of Indian hematite ores, reduction of losses and

increase in their quality’, Proc. 16th Int. Min. Process. Cong., (ed.

K. S. E. Forssberg), 1369–1380; 1988, Amsterdam, Elsevier.

25. B. P. Radhakrishna: ‘Archaean granite-greenstone terrain of the

South Indian Shield’, Geol. Soc. Ind. Mem., 1983, 4, 1–46.

26. B. P. Radhakrishna: ‘Mineral resources of Karnataka’, 471; 1996,

Bangalore, Geological Society of India.

27. B. P. Radhakrishna and R. Vaidyanadhan: ‘Geology of

Karnataka’, 353; 1997, Bangalore, Geological Society of India.

28. K. L. Rai, S. N. Sarkar and P. R. Paul: ‘Primary depositional and

diagenetic features in the BIF and associated iron ore deposits of

Noamundi, Singhbhum District, India’, Miner. Depos., 1980, 15,

189–200.

29. ‘Jilling-Langalota Iron Ore Mines’, unpublished result, Report of

ACC, 1997, 2–10.

30. S. Roy and A. Das: ‘Characterisation and Processing of low grade

iron ore from Jilling area of India’, Miner. Process. Extract. Metall.

Rev., 2008, 29, 213–231.

31. S. Roy, A. Das and M. K. Mohanty: ‘Feasibility to producing

pellet grade concentrate by beneficiation of iron ore slimes in

India’, Separat. Sci. Technol., 2007, 42, (14), 3271–3287.

32. S. Roy, A. Das and A. S. Venkatesh: ‘Characterisation of Iron Ore

from Jilling area of eastern India with a view to beneficiation’,

Proc. Iron Ore Conf., Perth, Australia, August 2007, AusIMM,

179–186.

33. M. V. Rudramuniyappa: ‘Iron ore fines and their impact on

environment in Sandur-Hospet region, Bellary district, Karnataka,

India’, Proc. Fines, Jamshedpur, India, 1997, NML, 273–278.

34. A. K. Saha: ‘Some aspects of the crustal growth of the Singhbhum-

Orissa iron ore craton, Eastern India’, Ind. J. Geol. 1988, 60, (4),

270–278.

35. A. K. Saha: ‘Crustal evolution of Singhbhum, North Orissa,

Eastern India’, Geol Soc. Ind. Mem, 1994, 27, 341.

36. P. Sampat Lyengar: ‘Report on the survey work in the Chitradurga

district’, Rec. Mysore Geol. Dep., 1905, 6, 57–116.

37. L. D. Santos and P. R. G. Brandao: ‘Morphological varieties of

goethite in iron ores from Minas Gerais, Brazil’, Miner. Eng., 2003,

16, 1285–1289.

38. T. Seshadri, A. Chaudhary, P. Harinadha Bapu and N.

Chayapathi: ‘Shimoga belt’, in: ‘Early Precambrian Supracrustals

of Souther Karnataka’, (ed. J. S. Nath and M. Ramakrishnan),

Geol. Soc. India, Mem., 1981, 112, 163–198.

39. M. Sonka: ‘Image processing analysis and machine vision’, 770;

2004, New Delhi, Thomson Books, Vikas Publication.

40. M. P. Srivastava, S. K. Pan, N. Prasad and B. K. Mishra:

‘Characterization and processing of iron ore fines of Kiriburu

deposit of India’, IJMP, 2001, 61, 93–107.

41. D. Taylor, H. J. Dalslra, A. E. Harding, G. C. Broadbent and M.

E. Barely: ‘Geneses of high grade Hematite ore Body of Hamersley

Provence, Western Australia’, Econ. Geol., 2001, 96, 837–873.

42. R. K. Upadhyay and A. S.Venkatesh: ‘A current strategies and

future challenges on exploration, beneficiation and value addition

of iron ore resources with special emphasis on iron ores from

eastern India’, Appl. Earth Sci., 2006, 115, (4), 187–195.

43. V. Von: ‘Die Metallogenetische Entwicklung Des Krivoy Rog-

Eisenerzbezirkes imUkrainischen Schild’, Dissertation, Berlin,

2001, 116.



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