Banded Hematite Quartzite Research Articles

A Study of Banded Hematite Quartzite (BHQ) in Mallasamudra Area, Gadag Schist Belt, Karnataka, India

Mineral raw material plays a very important role in the manufacturing industry as well as the country's economic growth. The iron ore, especially the Banded Iron Formations (BIFs) are unique rock formations in geological history. The Mallasamudra area, Gadag Schist Belt (GSB), is having good exposures of iron ores. Most of the outcrops of BHQ are located on the top of the hills whereas metabasalts occur on either side of the hills in the area. The BHQ were delineated during field mapping. In the Banded Hematite Quartzite (BHQ) of Mallasamudra area, SiO2 varies from 48.22% to 52.12% and Fe2O3 varies from 29.23% to 33.21% indicating that the BHQ is of low-grade.

Pioneer Studies on Metagenomic Evaluation of Diversity of Microbial Community in Banded Iron Formation (BIF) from Iron Ore Mining Belt of Goa, India

Goa is situated in the northwestern part of the Western Dharwar Craton (WDC) which is Asia’s major metallogenic province. The iron ore of Goa is associated with greenstone and occurs as bands, reefs, and lenses of Banded Hematite Quartzite (BHQ) and Banded Magnetite Quartzite (BMQ) none of these are explored for geo-microbiological dimensions, such as detection of microbioform Gold. The presence of metalliferous WDC in Goa affords sampling of auriferous materials from mining area having hitherto BHQ at latitude 15°29′54″ N and longitude 74° 03′44″ E) and BMQ at latitude 15°24′12″ N and longitude 74° 09′31″ E were collected, surface sterilized and drilled with a sterile driller to get the endolithic material under sterile conditions and sent for metagenomic analysis using Oxford nanopore sequencing. Both the samples showed the presence of microorganisms with Archea, such as Haloferax, Nitrososphaera, and Eubacteria, i.e., Bacillus, Ralstonia, Cupriavidus, Burkholderia, and Acetobacter. The traditional model of Banded Iron Deposition assumes precipitation by the oxidation of hydrothermal Fe (II), either via abiotic oxidation or biotic oxidation through chemo lithotrophic Eubacteria, such as cyanobacteria which produce oxygen. This paper reports the diversity and the presumptive role of these microorganisms in the biogeochemical cycling of metals, such as Fe, Mn, and gold (Au).

Recovery of Hematite from Banded Hematite Quartzite of Southern India by Magnetic Separation and Reverse Flotation

Recovery and grade are the two crucial performance parameters commonly used in mineral processing plant operations. These two parameters are interdependent. An increase in recovery would result in a decreased product grade and vice versa. The present study enumerates concentration efficiency (CE),which can be adopted exclusively for processing low-grade hematite ore by WHIMS—the reverse flotation route to produce a pellet grade concentrate. In this study, the ore’s amenability by wet high-intensity magnetic separation followed by the reverse flotation of a magnetic concentrate route is investigated on BHQ samples of the Sandur schist belt (Kumaraswamy hills), India, after its characterization by microscopic and XRD studies. Dodecyl amine acetate was used as a collector to float siliceous gangue while depressing hematite using the freshly synthesized caustic starch as a depressant. The separation efficiency of the flotation was evaluated by estimating the grade, recovery, and concentration efficiency. The WHIMS conducted using the feed with the particle size minus 106 µm (d80 = 82 µm) followed by reverse flotation produced a pellet grade concentrate assaying 64.60% Fe, a 0.32 alumina-to-silica ratio with 60.4% Fe recovery, and a yield of 37.4% with 79.0% concentration separation efficiency.

Resource Management and Utilization of Lean Grade Iron Ore Resources of Karnataka, India

As per the National Steel Policy 2017, more than 300 million tons of steel needs to be produced by 2030, to meet the increased demand due to the tripling of per capita consumption of steel in India. Accordingly, the local steel production from the Ballari steel hub of Sandur schist belt is expected to be raised from present 25 million tons per year to 60 million tons per year by 2030, thus necessitating 150 million tons of high grade hard lumpy/pellets for domestic Ballari steel hub alone excluding long term export commitments. Hence, a strategy for processing lean grade iron ores to augment the demand of high-grade iron ores for metallurgical applications is studied. A composite mixed Banded Hematite Quartzite (BHQ) from different ranges of Sandur schist belt, Ballari district, Karnataka, India was subjected to characterization, mineral processing and palletization studies to produce pellets Fe > 62.5 %, (SiO2+ Al2O3)2, 1.00 % Al2O3and 1.06 % LOI, comprising fine grained (<70 ?) mainly hematite [55–60%], very fine grained (<40 ?) quartz [35- 40%] and fine grained (<70 ?) minor amounts of martitized magnetite [1–5%], which are mutually intimately intermixed and intergrown, was subjected to beneficiation. The BHQ is amenable to gravity concentration by tabling reverse flotation, and WHIMS produces pellet grade concentrates. The final conventional process comprising gravity concentration, followed by magnetic separation of gravity tails and refining of magnetic fractions by reverse flotation. The final concentrate has produced assaying 64.5% Fe, 6.32% SiO2, 0.29% Al2O3 and 0.63% LOI, with 73% Fe distribution, has met the pellet grade specification. The pellets produced from beneficiated iron ore concentrate is assayed 64.10 % Fe, 6.85 % SiO2, 0.42 Al2O3%. DRI could be produced from the pellets from which steel is produced paving the way for conservation, sustenance, and sustainable development with the viability of using BHQ of the Sandur schist belt.

Processing Studies on Banded Hematite Quartzite’s of Sandur Sciht, Karnataka, India

The greater demand for high-quality iron ores has forced the iron and steel industries to utilize low-grade iron ores, such as banded hematite quartzite (BHQ). In the present work, a striped hematite quartzite sample from the Haraginadoni area, in the Sandur schist belt, Ballari District, Karnataka, India, was subjected to characterization studies and conventional mineral processing methods to produce pellet-grade concentrate, assayed as Fe > 63.0%, SiO2 + Al2O3 < 7%, (Al2O3/SiO2 < 0.5). The sample was analyzed as 35.70% Fe, 47.44% SiO2, 0.75% Al2O3, 0.06% Mn, 0.07% TiO2, 0.03% P, 0.02% S, and 0.83% LOI. We focused on two routes of beneficiating BHQ samples: (1) conventional gravity followed by reverse floatation and (2) magnetic separation followed by cleaning of magnetic concentrate by reverse floatation. Route 1, achieved pellet-grade concentrate through assaying, and was 63.73% Fe, 6.20% SiO2, 0.19% Al2O3, 0.03% Al2O3/SiO2, and 0.23% LOI, D80 45 µm, with 70.1% Fe recovery and 62.8% concentration efficiency at 39.6 wt% yield. Using Route 2, the process consisted of WHIMS at −74 µm, D80 54 µm, 10,000 Gauss, and with a 3 mm ball matrix, followed by flotation of the WHIMS concentrate, which produced a concentrate through assaying and was 63.34% Fe, 6.30% SiO2, 0.20% Al2O3 (0.03 Al2O3/SiO2), and 0.20% LOI with 77.4% Fe recovery, achieving a 68.8% concentration efficiency at 44.0 wt% yield, meeting pellet-grade specifications. Comparing and analyzing both routes for the concentration methods, Route 2, i.e., WHIMS and the reverse flotation of WHIMS concentrate, was amenable compared to Route 1.

Pelletization of hematite and synthesized magnetite concentrate from a banded hematite quartzite ore: A comparison study

A compressive pelletization study, for the utilization of an Indian Banded Hematite Quartzite ore, is presented in this communication. Iron ore concentrates have been generated utilizing the conventional beneficiation process and also by the approach of reduction roasting-magnetic separation. The Fe contents of the hematite and the synthesized magnetite concentrate were found to be 64.22 and 63.80%, respectively. The influence of different factors on the respective physical, chemical, and metallurgical properties of the fired pellets, generated through both the routes, have been compared. The pellets prepared from the synthesized magnetite attain the threshold Cold Crushing Strength (CCS) of 50 kg/pellet at a lower temperature of 1050 °C in comparison to hematite pellets (1100 °C). Also, the threshold CCS of 250 kg/pellet is attained by synthesized magnetite pellets at a lower temperature of 1250 °C compared to hematite pellets (1360 °C). The fired synthesized magnetite pellets also achieve the desired metallurgical properties i.e., Reduction Degradation Index (RDI), Reducibility Index (RI), and Swelling Index (SI) at par with the hematite pellets. Moreover, unlike the hematite pellets, the synthesized magnetite pellets do not need the addition of external carbon during the pellet making.

Characterization and mapping of hematite ore mineral classes using hyperspectral remote sensing technique: a case study from Bailadila iron ore mining region

The study demonstrates a methodology for mapping various hematite ore classes based on their reflectance and absorption spectra, using Hyperion satellite imagery. Substantial validation is carried out, using the spectral feature fitting technique, with the field spectra measured over the Bailadila hill range in Chhattisgarh State in India. The results of the study showed a good correlation between the concentration of iron oxide with the depth of the near-infrared absorption feature (R2 = 0.843) and the width of the near-infrared absorption feature (R2 = 0.812) through different empirical models, with a root-mean-square error (RMSE) between < 0.317 and < 0.409. The overall accuracy of the study is 88.2% with a Kappa coefficient value of 0.81. Geochemical analysis and X-ray fluorescence (XRF) of field ore samples are performed to ensure different classes of hematite ore minerals. Results showed a high content of Fe > 60 wt% in most of the hematite ore samples, except banded hematite quartzite (BHQ) (< 47 wt%).

Pelletization of synthesized magnetite concentrate obtained by magnetization roasting of Indian low-grade BHQ iron ore

In India, the use of iron ore pellets in the blast furnace, electric arc furnace, or sponge iron production is continuously optimized, considering different aspects of the production chain from the run of mining (ROM) to metallic iron depending upon the industrial need and ore availability (recent aggressive iron ore mining auction 2020 in India). The scarcity of high-grade iron ore resource and availability of the considerable quantity of low-grade iron ore fines, banded hematite quartzite (BHQ) ore in mines (mostly in Bihar, Odisha, Madhya Pradesh, and Karnataka), has to lead the way to beneficiate and utilize the concentrate as pellet feed for the steelmaking process. Banded iron ore such as BHQ is one of the potential resources of iron having a total iron content, i.e., Fe (T) of 35–48 wt%, which is lying unutilized in most of the Indian iron ore mines. The challenge before the policymakers and researchers is to think of a sustainable process technology to utilize these iron ore resources wisely. The conventional beneficiation of this type of siliceous BHQ iron ore resource having low iron content is not advisable. Therefore, pelletization of synthesized magnetite concentrate obtained from the magnetization roasting of BHQ emerged as an alternative energy-saving and ore conserving process that may be scaled up and commercialized for low-grade banded iron ores. The pelletization of magnetite concentrate is an independent heat hardening process; thereby requirement of anthracite coal fines as a fossil fuel additive to maintain the temperature gradient from core to the periphery of the pellet can be avoided. Physical properties such as cold crushing strength (CCS) and porosity of the pellets were optimized to study their suitability in the steelmaking process. In this regard, characterization studies of the pellets were performed using X-ray diffraction (XRD), scanning electron microscope (SEM), optical microscope, and X-ray micro-computed tomography to understand the microstructural properties of the pellets. The CCS of 255.8 kg/pellet and porosity of 25.42% were achieved at the optimized induration temperature and residence time of 1250 °C (50 °C to 80 °C less than conventional hematite pellet induration) and 10 min, respectively. The properties studied are encouraging and comparable with the pellet prepared from the natural magnetite/hematite ore.

Geochemical signatures of manganese ores around Barbil, Noamundi-Koira basin, Singhbhum Craton, Eastern India

ABSTRACT Palaeoproterozoic Noamundi – Koira Basin (NKB), on the western margin of the >3.0 Ga old Singhbhum Granitoid Complex, forms a horseshoe-shaped synclinorium. Volcanic rocks belonging to Bonai volcanic suite (BVS) occur outside and all-around the NKB that consists of three distinct but conformable stratigraphic units viz; Lower Shale Formation, Middle Banded Hematite Quartzite (BHQ) and/or Banded Hematite Jasper (BHJ) and Upper Shale Formation. The layered, lensoid, lateritoid, and vein type Mn-ore bodies are associated with the Upper Shale Formation. Compositions of the Mn ores widely variable values, SiO2 (1.00%- 16.40%), Al2O3 (1.62%-17.20%), Fe2O3 (10.55%-63.28%), MnO (31.75% −75.72%), Ni (25–260 ppm), Co (78–350 ppm), Zn (82–509 ppm) and Cr (13–187 ppm) clearly reflect their submarine hydrothermal source. Litho-stratigraphic considerations also lead to suggest that BHJ/BHQ and Mn-ore deposits of NKB are genetically related to the BVS. It is suggested that manganese and iron ores were deposited in a (? Forearc) basin associated with the mature island arc or active continental margin setting. FeO and MnO were added to the basin by hydrothermal solutes produced during the Bonai volcanism. BHQ/BHJ precipitation took place under a low redox potential while Mn-ore deposition is a consequence of the high redox potential.

Processing of Banded Hematite Quartzite Ore for Recovery of Iron Values

This study investigates upgrading of low-grade banded hematite quartzite iron ore (Fe ~31%). Conventional beneficiation was found to be futile. The susceptibility of iron phases to microwave exposure and their selective absorption assists in the liberation of iron values. Microwave exposure of coarse particles at 540 W for 10 min yielded a concentrate with Fe 56.30% and recovery of 50.68%. Conventional carbothermic reduction at 500 °C, 60 min and 9% charcoal yielded a concentrate with Fe 57.6% and iron recovery of 68%. The presence of sufficiently bonded silica leads to an easy formation of a fayalite phase. The microwave reduction design yielded FeG of 57.6%, FeR of 47% and a yield of 24% at an optimal condition of 540 W, 8 min and 6% charcoal. It was found that a small fraction of microwave-irradiated ore-charcoal mixture melted rapidly, and pure ferrite balls were observed within 8 min. An optical micrograph of a ferrite ball reveals the retained austenite and martensite phase.

Characterization and Comminution Studies of Low-Grade Indian Iron Ores

Banded hematite quartzite (BHQ) and banded hematite jasper (BHJ) ores represent a promising potential iron ore resource in the near future. The hematite and quartz in BHQ and the hematite and jasper in BHJ are closely related and require fine grinding for the liberation of hematite phases. The present study investigates the mineralogical features and comminution properties of BHQ and BHJ ores. In the BHQ ore, it is observed that thick bands of hematite have fine inclusions of silicate minerals, whereas silica bands have few grains of iron-bearing minerals. The hematite and quartz minerals in the iron and silicate bands of the BHJ ore appear to be more intricately associated and complex in nature, presenting difficulties for liberation. Bond work index studies were carried out for the BHQ and BHJ ores with different product fineness in order to evaluate the energy requirements in fine grinding. A higher Bond work index value was found for the BHJ ore (15.4 kWh/ton) than for the BHQ ore (12.4 kWh/ton). A decrease in the product particle size was associated with an increase in the work index value. Single-particle breakage experiments were designed by varying feed particle size and input energy. The specific energy consumption for the BHJ ore was higher than that for the BHQ ore. The comminution parameters showed that the BHJ ore is harder to grind than the BHQ ore, which may be due to the mineral composition and association of hematite phases with the silicates.

Utilization of low-grade BHQ iron ore by reduction roasting followed by magnetic separation for the production of magnetite-based pellet feed

Due to the depletion of high-grade iron ores and their simultaneous demand, the utilization of low-grade iron ores such as banded hematite quartzite (BHQ) has become a topic of research interest around the globe, particularly in India. These low-grade iron ores are reckoned to be the future feedstock for iron and steel making industries. However, one of the major challenges is to remove associated gangue impurities from such low-grade iron ores by the conventional beneficiation techniques prior to its industrial applications. The reduction roasting process is one of the potential alternatives to overcome such challenges. Herein, we have presented the feasibility study using reduction roasting process on one of the Indian low-grade BHQ iron ore for the preparation of magnetite concentrate-based pellet feed materials. To establish the methodology of the reduction roasting process, different experimental parameters such as roasting temperature, reductant dosage, roasting time and fixed carbon were optimized for obtaining the maximum recovery, yield, and grade of the magnetite products. In the present study, Indian non-coking coals were used as reductant due to its large availability in the country. Using one of the non-coking coals as reductant, the optimum condition were found to be as, roasting temperature: 1100 °C, roasting time: 5 min, and head sample to reductant ratio: 10:6. Under these conditions, maximum grade and recovery of final magnetite concentrates were found to be 66.42 and 93.53%, respectively. It is expected that the large-scale development of reduction roasting process would lead to effective utilization of low and lean grade iron ore resources for the production pellet feed materials in the Indian context and simultaneously conserve the natural magnetite ores for future generation.

Physical, Mechanical and Metallurgical Characteristics of Banded Hematite Jasper of Ghatkuri (Gua), Jharkhand

ABSTRACT Quick depletion rate of high-grade iron ore paved to emphasise on banded hematite jasper and banded hematite quartzite with ∼30-40% iron. In the present investigation, efforts have been made to characterize the banded hematite jasper of Ghatkuri area (Gua), west Singhbhum, Jharkhand, India. The banded hematite jasper of the study area have complex physical and mineralogical character. X-ray diffraction analysis indicated that silica and iron are the major phases whereas alumina and goethite are the gangue mineral. Thermo-gravimetric analysis revealed it to be oxy-hydrated with iron in hematite phase. Vickers hardness test and bond work index revealed hard and compact nature of the ore. Grain size analysis shows the maximum concentration of the elements at the size range of -125+106 μm whereas minimum at -212+180 μm.

Use of Banded Hematite Quartzite (BHQ) in Blast Furnace for Partial Replacement of Quartzite

Hot metal produced through blast furnace (BF) route is still the most preferred route in majority of the steel industries. In the blast furnace operation, quartzite is used as flux to adjust the desired slag chemistry and basicity (B2 of 1–1.08) to achieve optimum slag properties such as low liquidus temperature, high Sulphur carrying capacity and low viscosity. This paper describes the investigations carried out at JSW Steel Ltd to identify alternate sources of silica other than quartzite for use as flux in BF to maintain the desired slag chemistry for smooth operation and cost reduction. Banded hematite quartzite (BHQ) ore available in Karnataka region contains 28–33% Fe, 45–46% silica, 1.3–1.5% alumina and is found suitable for use as partial replacement for quartzite in blast furnaces. Mineralogy and phase analysis of BHQ reveals alternate bands of hematite and silica whereas in lump ore, hematite and silica are uniformly distributed. This phase distribution and reducibility index of BHQ (~66%) affect the softening start temperature by forming fayalite (2FeO·SiO2) as primary slag. Fines generations are found to be comparatively higher (from 6.3 to 6.4%) but in acceptable range. The Fe content in the BHQ also contributes to the overall Fe input to the furnace favoring an option to reduce the equivalent amount of iron bearing materials in the charge. Plant trials at JSW steel blast furnace #4, indicate an improvement in overall operational performance resulting in increased Fe input per charge, reduction in slag rate by 8 kg/thm due to low alumina input and easier achievement of final slag chemistry.

Flotation of quartz using ionic liquid collectors with different functional groups and varying chain lengths

The application of imidazolium, ammonium, and pyridinium based ionic liquids (ILs) as the flotation collectors of quartz has been investigated. The flotation studies have been carried out for pure quartz, quartz-hematite synthetic mixture and a low grade banded hematite quartzite (BHQ) ore while the trend of floatabilities has been explained in terms of the structural differences of the ILs. The flotation of pure quartz using the ammonium and pyridinium based IL collectors has exhibited an excellent performance; where about 100% quartz could be floated at a collector concentration of 5∗10−5M. The results are found better compared to the imidazolium ILs and conventional quartz collectors like dodecylamine (DDA) and cetyl trimethyl ammonium bromide (CTAB). The ammonium and pyridinium based collectors also show better iron grade and recovery compared to the imidazolium collectors during the reverse flotation of the synthetic hematite-quartz mixture and BHQ ore. Using these collectors, an iron ore concentrate of ∼62% Fe at ∼75% recovery could be obtained from the BHQ ore containing ∼38% Fe. In the Fourier Transform Infra Red spectroscopy (FTIR), the peak intensity at 2900cm−1 due to the presence of alkyl groups signifies the extent of adsorption of the collectors on quartz. The N/Si ratio and CC peak area as determined by the X-ray photoelectron spectroscopy (XPS) results show the relative adsorption of the IL collectors. The pyridinium based IL collector show better adsorption strength compared to all others ILs under study. The better flotation results in the case of the ammonium and pyridinium collector are attributed to the presence of higher alkyl chain length inducing better hydrophobicity.

Ionic liquids as novel quartz collectors: Insights from experiments and theory

Application of quaternary ammonium based ionic liquids (IL’s) as flotation collectors of quartz has been investigated. Effect of number of carbon atoms in the four identical alkyl chains of the IL’s has been studied. The adsorption behaviour of the IL’s on the quartz surface is ascertained through FTIR, XPS and molecular modelling. The FTIR peak at 2900cm−1 indicates the adsorption of the IL’s onto the quartz surface, which is further substantiated by the appearance of the N (1S) peak in the X-ray photoelectron spectra (XPS). Curve splitting data of C (1S) suggests the maximum adsorption for the IL tetrahexylammonium iodide (THEX). Flotation results of pure quartz using ionic liquids are found to be better compared to the conventional collectors such as dodecylamine (DDA) or cetyltrimethylammonium bromide (CTAB). It is possible to float 92–100% quartz by using a THEX concentration of 4.8 × 10−5M. IL collectors are further applied in the flotation of a low grade banded hematite quartzite (BHQ) iron ore with ∼38% Fe. It is possible to achieve an iron concentrate of 63.6% Fe at 63.2% recovery by using THEX as the collector. Molecular simulations using the COMPASS forcefield explains the IL–quartz adsorption mechanism comprising of both electrostatic and van der Waals forces. Floatability of quartz has been correlated with the surface coverage and adsorption energy calculations. The IL’s used here are found to be better quartz collectors than the conventional ones as they show better collecting efficiency in lower dosages. Flotation using these IL’s does not require frothers which is an added advantage compared to the conventional collectors.

Aliquat-336 as a novel collector for quartz flotation

The study illustrates the first ever use of Aliquat-336 (C25H54ClN), an ionic liquid, in the flotation separation of quartz from hematite. Laboratory flotation studies of hematite, quartz and their synthetic mixture have shown selective collecting action of Aliquat-336 toward quartz. At an Aliquat-336 dosage of 280g/t, 97% quartz is floated at slightly alkaline pH (∼8), whereas hematite recovery is only 8%. Flotation of the synthetic mixture of hematite: quartz (1:1), with Aliquat-336 as the quartz collector and starch as the hematite depressant, has resulted in an iron concentrate of 63–65% Fe with 85–88% recovery. The reverse flotation behavior of the low grade banded hematite quartzite (BHQ) using Aliquat-336 as the collector has been investigated. It is observed that, iron values up to ∼65% Fe with 60% recovery can be achieved from the ore containing ∼38% Fe. Surface potential measurement and FTIR spectra lead to the indication of electrostatic adsorption between Aliquat-336 and quartz.

Estimation of Bulk Density, Recovery Tests and Mineralogical Analysis of Iron Ore Mine at Obulapuram Village, Anantapur District, Andhra Pradesh

The iron ore formation belongs to Precambrian, Dharwarian age. The lithological formations consists of Sedimentary and metamorphic rocks represented by Quartzite, shale, slate and phylites and iron ore occurring in from the mainly massive and fairable brown color hematite type presented. Source rock belongs to Banded hematite quartzite (BHQ) formation. The main Iron ore had been initially worked as open pit method of mining. The Hematite ore concentration mainly along the ferruginous shale and at some places pyrites are encountered. The recovery percentage of iron ore samples varied from 58.50%, 63% and 61%, the average being the float ore recovery is around 43%.The float ore occurs to a limited thickness of 1m and the workings are being carried out forming single bench to a maximum height of 3m from the surface. The results of the bulk density determined in the field for iron ore shown are 2.98 to 3.03. The average bulk density for float ore can be taken as 2.51. In the case of Iron ore the average works out to be 2.88.

Influence of band thickness of banded hematite quartzite (BHQ) ore in flotation

Hematite and quartz present in banded iron ore are intimately associated with one another and require fine grinding for the liberation of mineral particles. The influence of the thickness of bands on the liberation and flotation response of banded hematite quartzite (BHQ) ore is investigated. A computer program is developed to predict the liberation of banded iron ores based on different patterns of banding. It is found that the phase which is distributed in thick bands is better liberated compared to thin bands. QEMSCAN studies on BHQ samples have shown similar trends. The direct and reverse flotation behavior of the BHQ ore using oleic acid and dodecylamine respectively was determined. In reverse flotation, 64.4% Fe at 59% recovery could be obtained from an ore having thick quartz bands, whereas under identical conditions, only 60.6% Fe at 64.8% recovery could be obtained with thin bands. In the case of direct flotation, it is possible to achieve 63.8% Fe at 50.7% recovery for the ores with a thick quartz band and 62.7% Fe at 58.1% recovery for the thin band.

Optimization of flotation variables for the recovery of hematite particles from BHQ ore

The technology for beneficiation of banded iron ores containing low iron value is a challenging task due to increasing demand of quality iron ore in India. A flotation process has been developed to treat one such ore, namely banded hematite quartzite (BHQ) containing 41.8wt% Fe and 41.5wt% SiO2, by using oleic acid, methyl isobutyl carbinol (MIBC), and sodium silicate as the collector, frother, and dispersant, respectively. The relative effects of these variables have been evaluated in half-normal plots and Pareto charts using central composite rotatable design. A quadratic response model has been developed for both Fe grade and recovery and optimized within the experimental range. The optimum reagent dosages are found to be as follows: collector concentration of 243.58 g/t, dispersant concentration of 195.67 g/t, pH 8.69, and conditioning time of 4.8 min to achieve the maximum Fe grade of 64.25% with 67.33% recovery. The predictions of the model with regard to iron grade and recovery are in good agreement with the experimental results.