[Show abstract][Hide abstract] ABSTRACT: Magnetite nanoparticles were synthesized from iron ore tailings; - a mineral waste collected from the iron ore processing plant. Mechanical milling followed by chemical route is employed to obtain the magnetite nanoparticles from the waste. The magnetite nanoparticles were characterized by X-ray diffractometer, Field Emission Scanning Electron Microscope, Fourier Transform Infrared Spectrometer and Vibrating Sample Magnetometer. X-ray diffraction pattern confirms the existence of a magnetite phase. Field Emission Scanning Electron Microscopic (FE-SEM) pictures reveal that the particle size is below 100 nm. Fourier Transform Infrared (FTIR) spectrum shows a band at 570 cm-1 for the Fe-O bond vibration. Vibrating Sample Magnetometric (VSM) study shows high saturation magnetization value of 60 emu/g at low applied magnetic field. Silver coated magnetite nanoparticles exhibits antibacterial property whereas bare magnetite does not.
Journal of Alloys and Compounds 10/2015; 645:398-404. DOI:10.1016/j.jallcom.2015.05.089 · 3.00 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Comminution is an energy intensive process. A small change in efficiency can lead to substantial benefits in an overall economy of the process plant. This study focussed on the comparison of vertical stirred mill agitator designs. A double helical screw agitator was designed for this purpose. A series of stirred mill experiments were performed with two types of agitator designs a standard pin type and CSIRO’s designed double helical screw stirrers. The effects of operating parameters such as grinding time, stirrer speed and pulp density on grinding performance was investigated using a magnetite concentrate. Grinding performance was analysed by considering the product fineness and the energy consumption. The test results show that the grinding time and stirrer speed played a significant role, however, the pulp density had little impact on grinding performance in both cases of agitator designs. The 80 % passing target product size of 38 μm was obtained with double helical screw agitator in 20 min of grinding with an expend of 10.53 kWh/t specific energy. Whereas, the target product size of 38 μm was achieved with the pin type stirrer at the rate of 21.73 kWh/t. It is evident that grinding in a vertical stirred mill with a double helical screw is more efficient than that using a pin type stirrer in terms of the product size distribution and the specific energy consumption. It is concluded that the double helical screw design provides better energy efficiency compared to the pin type stirrer design. The models were developed for the responses P80 and Ecs. Both models show high regression coefficients thus ensuring a satisfactory of models with experimental data. The model equations developed were then optimized using a quadratic programming to minimize the P80 size at minimum specific energy.
Separation Science and Technology 07/2015; DOI:10.1080/01496395.2015.1065888 · 1.17 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Yttrium oxide (Y2O3) is one of the most stable oxides to withstand at high temperature and suitable for use as a dispersoid in oxide dispersion strengthened (ODS) steel alloy. In this paper, Y2O3 nano-powders are synthesized by three different techniques namely mechanical milling, single fuel combustion synthesis and mixed fuel combustion synthesis. In mixed fuel, various combinations of fuels are used instead of a single fuel (glycine, citric acid, urea, and ethylene glycol). Thermal characteristics and crystalline nature of Y2O3 nano powders produced by different techniques are analyzed extensively. Y2O3 nano powders with amorphous to nano-crystalline structure and having 8–80 nm crystallite size are obtained from the mixed fuel process, that is suitable for use as dispersiod in ODS steel. Further, these powders are dispersed in ferritic steel matrix using an innovative dual drive planetary ball mill to produce Y2O3 dispersed ODS steel powder within a short time period. Transmission electron microscopy analysis of milled oxide dispersion strengthened steel powder reveals a homogeneous distribution of Y2O3 nano powders in ferritic steel matrix after milling time of 5 h.
[Show abstract][Hide abstract] ABSTRACT: Mg-7.6% Al (in mass fraction) alloy matrix composites reinforced with different volume fractions of nanocrystalline Al3Ca8 particles were synthesized by powder metallurgy, and the effect of the volume fraction of reinforcement on the mechanical properties was studied. Room temperature compression test reveals considerable improvement on mechanical properties as compared to unreinforced matrix. The compressive strength increases from 683 MPa for unreinforced alloy matrix to about 767 and 823 MPa for the samples having 20 and 40 vol% of reinforcement, respectively, while retaining appreciable plastic deformation ranging between 12 and 24%. The specific strength of the composites increased significantly, demonstrating the effectiveness of the low-density Al3Ca8 reinforcement.
[Show abstract][Hide abstract] ABSTRACT: The rapid proliferation of electronic devices in the last two decades has compelled the researchers to find a remedy for one of the most toxic and hazardous waste materials – the waste Printed Circuit Boards. Numerous articles have been published demonstrating the process routes for recycling of this toxic but otherwise useful waste due to nearly 30% metal content. In this paper, more than 150 related articles mostly published in the last 15 years and covering the broad areas like characterization of waste Printed Circuit Boards, health hazards associated with the processing and the different routes of recycling have been analyzed to provide a comprehensive overview on this topic. Physical separation processes employing electrostatic separator, magnetic separator, froth floatation, etc., has been reviewed for separation of metals and non-metals, along with useful utilizations of the non-metallic materials. The recovery of metals from this waste material through pyrometallurgical, hydrometallurgical or bio-hydrometallurgical routes is also critically discussed.
Journal of Cleaner Production 02/2015; 94. DOI:10.1016/j.jclepro.2015.02.024 · 3.84 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Tin has many important properties and thus it finds wide applications in metal coating, tin plating, alloying, soldering, and plumbing, as well as in the electronic, electrical, and organotin compounds industries, etc. The metal is chiefly produced from the mineral cassiterite, which is generally beneficiated following gravity concentration and flotation techniques. Cassiterite beneficiation has contributed significantly to the understanding of fundamentals in mineral processing. In particular, the influence of particle size in gravity concentration and flotation techniques has been revealed. Basic research on flotation, such as the development of specific surfactants and the adsorption behaviour of these onto mineral surfaces has been performed. In the present review paper, an attempt has been made to summarize the role of particulate properties in gravity concentration and adsorption behaviour of flotation surfactants with regard to cassiterite. Past tin beneficiation plant practices are reviewed in detail including process flowsheet developments which have taken place over time.
[Show abstract][Hide abstract] ABSTRACT: 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 280 g/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.
[Show abstract][Hide abstract] ABSTRACT: The paper reports on reduction of cobalt oxide (Co3O4) to cobalt metal by low temperature hydrogen plasma. Hydrogen flow rate was varied between 1.167 × 10−6 to 2.5 × 10−6 m3 s−1 at a fixed microwave power of 750 W which gave rise to increase in pressure from 1.866 × 103 to 2.933 × 103 Pa and increase in temperature of the plasma-cobalt oxide interface from 823 to 1,039 K. Reduction of cobalt oxide to cobalt occurred in steps: Co3O4 → CoO → Co. The chemical reaction leading to reduction of cobalt oxide to cobalt is found to be first order with respect to hydrogen flow rate. The activation energy for the first stage of reduction i.e. Co3O4 to CoO is found to be 26.2 kJ/mol and that for the second stage reduction of CoO to Co metal is 13.3 kJ/mol.
[Show abstract][Hide abstract] ABSTRACT: Nepheline syenite is a complex rock consisting of different mineral phases such as nepheline, alkali feldspar, and biotite. It is a promising source for the recovery of potassium and alumina values. India is importing most of its potassium demand from the global market. An attempt is therefore made to extract potassium values from nepheline syenite available in the state of Odisha. It contains 2.8% Fe2O3, 19.9% Al2O3, 55.5% SiO2 and 5.4% K2O as its prime constituents. Magnetic separation and flotation techniques are found unsuitable to recover appreciable amounts of potassium values. Chemical leaching with dilute sulphuric acid could recover only ~ 40% of the potassium values. The potassium values present in nepheline syenite are unlocked through roasting with calcium chloride followed by water leaching. In this approach, it is possible to recover ~ 99.6% K2O value at 900 °C temperature and 30 min of roasting time. The results indicate that the use of planetary mill grinding prior to roasting is favorable for potassium extraction due to mechanical activation of the potassium bearing phases. The different mineral phases present in the feed and the leach residue have been characterized by using optical microscope, XRD and SEM-EDX which shows a phase conversion of locked potassium into sylvite which is soluble in water.
International Journal of Mineral Processing 12/2014; 133. DOI:10.1016/j.minpro.2014.09.006 · 1.31 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: PurposeTo report retinopathy in a series of four babies unusually beyond the screening standards reported so far in the literature.Methods
During routine screening for retinopathy of prematurity, we detected retinopathy in four babies who were surprisingly bigger and older than the screening standards. The gestational age (GA), birth weight (BW), post menstrual age at first examination and significant perinatal events were noted. The retinopathy details imaged by the RetCam were classified as per ICROP revisited standards.ResultThe GA ranged from 36 to 39 weeks and BW from 2.4 to 3.0 kg. Three of them had retinopathy in zone III that regressed spontaneously and one had marked plus with vascular arcades and shunts in zone II that regressed after laser photocoagulation. All of them had fetal distress and multiple systemic comorbidities in the neonatal period.Conclusion
This report makes one aware of the possibility of retinopathy in newborn of older GA and larger BW especially with fetal distress and stormy neonatal course.Eye advance online publication, 31 October 2014; doi:10.1038/eye.2014.253.
[Show abstract][Hide abstract] ABSTRACT: The abrasive wear characteristics of plasma-sprayed nanostructured yttria-stabilized zirconia (YSZ) coatings on Inconel 718 substrates was evaluated using AFS 50/70-grade silica sand as abrasives. This article depicts the dependence of abrasive wear characteristics of plasma-sprayed nanocomposite LaCeYSZ coatings on abrading distance, keeping the applied load constant. The influence of four operating parameters—that is, load, wheel speed, time, and temperature with four different levels each—on the performance output (i.e., abrasion wear rate) is studied using Taguchi's L16 orthogonal array design and analysis of variance (ANOVA). Out of the four parameters, load has been found to be most significant factor followed, by speed of the abrasive wheel and temperature influencing abrasion. The morphology of the worn-out surface also showed microcutting and small crater formation in the binder matrix caused by the repetitive impacts of abrasive particles. It was observed that coating with nano-LaCeYSZ grains exhibited higher wear resistance compared to conventional YSZ coating and the reason may be attributed to embedded crack-arresting nanozones, which toughen the coating. An artificial neural network (ANN) approach is then implemented taking into account training and test procedures to predict the triboperformance under different operating conditions. This technique helps in saving time and resources for a large number of experimental trials and successfully predicts the wear rate of the coatings both within and beyond the experimental domain.
[Show abstract][Hide abstract] ABSTRACT: A low grade iron ore containing 51.6% Fe, 17.6% SiO2, 4.3% Al2O3, and 3.8% LOI was subjected to reduction roasting followed by low intensity magnetic separation studies. The phase transformation of hematite into magnetite and fayalite due to reduction roasting was investigated using reflected microscope and X-ray diffraction (XRD) techniques. The effects of reduction variables such as reduction time (40−175 min), temperature (750−1000°C), and reductant dosage (3−11%) using activated charcoal were studied. The process was optimized by using central composite rotatable design (CCRD) and response surface methodology. Iron grade from 59−66% with recovery of 9.5−87% was achieved using CCRD experiments. Model equations were developed both for Fe grade and recovery and then optimized within the bounds of experimental conditions. The program predicted 63.3% Fe with 79% recovery with the following optimum conditions: temperature: 950°C, time: 53.04 min, and reductant: 3%.
[Show abstract][Hide abstract] ABSTRACT: Investigations were carried out to understand the design aspects of tribo-electrostatic separator to separate ash from high ash Indian coking coal. Initial studies were aimed to evaluate the different physical, chemical and electrical properties of quartz, kaolinite, and carbon particles. The significant design variables such as plate angle and plate gap were evaluated to effect the optimum separation. The absolute charge acquired by quartz, kaolinite, and carbon were observed to be different. The results indicate that the magnitude of charge increases with the increase in the time of tribo-charging using copper tribo-charging medium. A mathematical model was formulated based on design and operating parameters of the experimental set up to simulate the particle trajectories. The particle trajectories were simulated using measured physical and electrical properties of mineral and carbon particles at experimental design and operating conditions. The simulated trajectories were validated with experimental data. The results of plate position and feed particle temperature indicated that there were optimum conditions to achieve the desired performance. The simulation and experimental results were in good agreement. The optimum separation was achieved at plate inclination of 5°. It was possible to reduce ash content by 10% at 61% yield. Better quality clean coal at 33% ash was achieved from 53% ash feed coal with lower yield.
[Show abstract][Hide abstract] ABSTRACT: This article describes the influence of controlling in-flight hot particle characteristics on properties of plasma sprayed nanostructured yttria stabilized zirconia (YSZ) coatings. This article depicts dependence of adhesion strength of as-sprayed nanostructured YSZ coatings on particle temperature, velocity and size of the splat prior to impact on the metallic substrate. Particle temperature measurement is based on two-color pyrometry and particle velocities are measured from the length of the particle traces during known exposure times. The microstructure and adhesion strength of as-sprayed nano-YSZ coatings were studied. Field emission scanning electron microscopy results revealed that morphology of coating exhibits bimodal microstructure consisting of nano-zones reinforced in the matrix of fully melted particles. The coating adhesion strength is noticed to be greatly affected by the melting state of agglomerates. Maximum adhesion strength of 42.39 MPa has been experimentally found out by selecting optimum levels of particle temperature and velocity. The enhanced bond strength of nano-YSZ coating may be attributed to higher interfacial toughness due to cracks being interrupted by adherent nano-zones.
International Journal of Smart and Nano Materials 07/2014; 5(3):207-216. DOI:10.1080/19475411.2014.941041
[Show abstract][Hide abstract] ABSTRACT: Plasma-sprayed thermal barrier coatings are frequently subjected to impacts by solid particles, which induce surface erosion. This article depicts the solid particle erosion response of plasma sprayed nanostructured yttria-stabilized zirconia (YSZ) coatings on Inconel 718 substrates. The influence of five operating parameters i.e. impact velocity, erodent size, erodent temperature, impingement angle, and stand-off distance with four different level each, on performance output (i.e. erosion rate) are studied using Taguchi's L-16 orthogonal array design. Out of the five parameters, impact velocity has been found to be most significant factor followed by erodent temperature and impingement angle influencing erosion. Maximum erosion takes place at an impingement angle of approximate to 60 degrees showing the semi-ductile response of the coating to solid particle erosion. The morphology of the eroded surface also showed micro-cutting and small crater formation in the binder matrix caused by the repetitive impacts of erodent particles. It was observed that coating with nano-YSZ grains exhibited higher erosion resistance compared to conventional YSZ coating.
ARCHIVE Proceedings of the Institution of Mechanical Engineers Part J Journal of Engineering Tribology 1994-1996 (vols 208-210) 07/2014; 228(8):872-880. DOI:10.1177/1350650114535385 · 0.92 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Recent Reports from Fakir Mohan Univ ersity Highlight Findings in Nanoparticles (Microalga Scenedesm us sp.: A potential low-cost green m achine for silv er nanoparticle sy nthesis) By a News Reporter-Staff News Editor at Biotech Week --Data detailed on Nanoparticles hav e been presented. According to news reporting originating from Balasore, India, by NewsRx correspondents, research stated, "Bionanotechnology has rev olutionized nanom aterial sy nthesis by prov iding a green sy nthetic platform using biological sy stem s. Am ong such biological sy stem s, m icroalgae hav e trem endous potential to take up m etal ions and produce nanoparticles by a detoxification process." Our news editors obtained a quote from the research from Fakir Mohan Univ ersity , "The present study explores the intracellular and extracellular biogenic sy ntheses of silv er nanoparticles (SNPs) using the unicellular green m icroalga Scenedesm us sp. Biosy nthesized SNPs were characterized by AAS, UV-Vis spectroscopy , TEM, XRD, FTIR, DLS, and TGA studies and finally checked for antibacterial activ ity . Intracellular nanoparticle biosy nthesis was initiated by a high rate of Ag(+) ion accum ulation in the m icroalgal biom ass and subsequent form ation of spherical cry stalline SNPs (av erage size, 1 5-2 0 nm) due to the biochem ical reduction of Ag(+) ions. The sy nthesized nanoparticles were intracellular, as confirm ed by the UV-Vis spectra of the outside m edium . Furtherm ore, extracellular sy nthesis using boiled extract showed the form ation of well scattered, highly stable, spherical SNPs with an av erage size of 5-1 0 nm . The size and m orphology of the nanoparticles were confirm ed by TEM. The cry stalline nature of the SNPs was ev ident from the diffraction peaks of XRD and bright circular ring pattern of SAED. FTIR and UV-Vis spectra showed that biom olecules, proteins and peptides, are m ainly responsible for the form ation and stabilization of SNPs. Furtherm ore, the sy nthesized nanoparticles exhibited high antim icrobial activ ity against pathogenic gram -negativ e and gram -positiv e bacteria."
[Show abstract][Hide abstract] ABSTRACT: Hematite and quartz present in banded iron ore are intimately associated with one another and require fine grinding for liberation of mineral particles. The influence of 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 case of direct flotation, it is possible to achieve 63.8% Fe at 50.7% recovery for the ores with thick quartz band and 62.7% Fe at 58.1% recovery for the thin band.
International Journal of Mineral Processing 07/2014; 130. DOI:10.1016/j.minpro.2014.05.006 · 1.31 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: A novel leaching process for recovering Zn from spent catalyst in alkaline solution has been discussed. The catalyst was characterized for physico-chemical properties by chemical, XRD, TG-DTA and SEM. More than 92% Zn could be extracted from spent catalyst under the conditions: pulp density 2.5% (w/v), NaOH 1 M, EDTA 0.025 M, temperature 80 degrees C and time 3 h. Zn extraction increased with the number of stages. At the 4th stage almost all Zn could be extracted. A tentative process flow-sheet has been proposed based on Zn recovery. Characterization of leach residue by XRD and SEM gave an insight into the mechanism.
Journal of Industrial and Engineering Chemistry 07/2014; 20(4):2217-2223. DOI:10.1016/j.jiec.2013.09.053 · 3.51 Impact Factor