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Microbial leaching of chromite overburden from Sukinda mines,Orissa,India using Aspergillus niger

International Journal of Minerals,Metallurgy and materials 2013年第8期20卷 705-712页

作者： Supratim Biswas Saikat Samanta Rajib Dey Siddhartha Mukherjee Pataki C.Banerjee department of metallurgical and material engineering Jadavpur UniversityKolkata-700032India school of materials science and nanotechnology Jadavpur UniversityKolkata-700032India

Leaching of nickel and cobalt from two physical grades （S1, 125-190 μm, coarser and S3, 53-75 μm, finer） of chromite overburden was achieved by treating the overburden （2% pulp density） with 21-d culture filtrate of an Aspergillus niger strain grown in sucrose medium. Metal dissolution increases with ore roasting at 600℃ and decreasing particle size due to the alteration of microstructural properties involving the conversion of goethite to hematite and the increase in surface area and porosity as evident from X-ray diffraction （XRD）, thermogravimetry-differential thermal analysis （DT- TGA）, and field emission scanning electron microscopy （FESEM）. About 65% Ni and 59% Co were recovered from the roasted S3 ore employing bioleaching against 26.87% Ni and 31.3% Co using an equivalent amount of synthetic oxalic acid under identical conditions. The results suggest that other fungal metabolites in the culture filtrate played a positive role in the bioleaching process, making it an efficient green approach in Ni and Co recovery from lateritic chromite overburden.

关键词： nickeliferous laterite bioleaching Aspergillus niger chromite nickel metallurgy cobalt metallurgy

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Kinetic studies on the reduction of iron ore nuggets by devolatilization of lean-grade coal

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International Journal of Minerals,Metallurgy and materials 2016年第12期23卷 1360-1368页

作者： Chanchal Biswas Prithviraj Gupta Arnab De Mahua Ghosh Chaudhuri Rajib Dey department metallurgical and material engineering Jadavpur University department of Metallurgy and materials engineering Indian Institute of EngineeringScience & Technology school of materials science and Nano Technology Jadavpur University

An isothermal kinetic study of a novel technique for reducing agglomerated iron ore by volatiles released by pyrolysis of lean-grade non-coking coal was carried out at temperature from 1050 to 1200℃ for 10-120 min. The reduced samples were characterized by scanning electron microscopy, energy-dispersive X-ray spectroscopy, and chemical analysis. A good degree of metallization and reduction was achieved. Gas diffusion through the solid was identified as the reaction-rate-controlling resistance; however, during the initial period, particularly at lower temperatures, resistance to interfacial chemical reaction was also significant, though not dominant. The apparent rate constant was observed to increase marginally with decreasing size of the particles constituting the nuggets. The apparent activation energy of reduction was estimated to be in the range from 49.640 to 51.220 kJ/mol and was not observed to be affected by the particle size. The sulfur and carbon contents in the reduced samples were also determined.

关键词： iron ore reduction coal devolatilization kinetic studies

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HIGH DIELECTRIC CONSTANT COMPOSITE BASED ON CHLOROPHYLL A ENTRAPPED NANOPOROUS SILICA GEL

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Journal of Advanced Dielectrics 2012年第3期2卷 64-72页

作者： J.S.MANNA M.K.MITRA S.MUKHERJEE G.C.DAS department of metallurgical and material engineering school of material science and nanotechnology jadavpur university Kolkata 700032India

Chlorophyll a(naturally occurring Mg porphyrene)has been entrapped in nano/porous silica gel using sol-gel method at room temperature,producing a stable *** TEM observationreveals regular nanoscale[around 15-20 nm diameter]distribution of aggregated polycrystalinechlorophylla within porous silica ***-vis study also corroborates the presence of variousaggregated chlorophyll a species within the *** field measurement shows almost 400times enhancement of dielectric constant(1700)with incorporation of only 0.125 mg/ml of chlorophyll and the loss is 0.5 at room temperature at 100 *** dielectric constant of the composite reaches 2500 as chlorophyll concentration becomes 1 mg/*** strong space charge response to the external field and strong frequency dispersion of the dielectric properties ofthe composite can be attributed to the long-range electron delocalization[nomadic polarization]in chlorophyl a *** electric modulus(M*)formalism used in this study enabled us todistinguish and separate various relaxation *** is found that with increasing chlorophyll concentration *** time decreases exponentially at room *** is shown that observed relaxations do not perfectly follow the Debye response in high frequency region due toheterogeneous distribution of chlorophyll *** low values of room temperature acti-vation energy calculated from Arrhenius plot reveal that polaronic hopping phenomena is absent at grain-interfacial region due to low thermal energy.

关键词： Nanoporous silica gel chlorophyll a dielectric dipole relaxation activation energy

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Comparative Studies on Synthesis and Characterization of Titania and Iron Oxide Doped Magnesia from Indian Salem Magnesite

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Journal of materials science and Chemical engineering 2016年第7期4卷 67-76页

作者： Sukriti Manna Tamoghna Chakrabarti department of metallurgical and material engineering Jadavpur University Kolkata India department of Mechanical engineering Colorado School of Mines Golden CO USA department of materials engineering Indian Institute of Science Bangalore India

Sintering, densification, and characterization of Salem Magnesite with Titania (TiO2) and Iron Oxide (Fe2O3) addition have been carried out in this work. Salem Magnesite samples with 2 wt.% TiO2 and Fe2O3 addition have been sintered in the temperature range of 1550?C - 1650?C. The sintered sample has been characterized in terms of physico-chemical properties like bulk density, apparent porosity, specific gravity and structural properties by X-ray diffraction and scanning electron microscope (SEM). Salem magnesite samples with 2 wt.% TiO2 and Fe2O3 addition have been densified to the specific gravity of 3.75 and 3.41 g/cc respectively after sintering at 1650?C and 2 h. The presence of Calcium Titanate (CaTiO3) phase at the grain boundary has been observed in the case of TiO2 addition. For Iron Oxide addition, precipitation of “Y” shaped magnesium ferrite spinel has been observed inside the grains. Finally, TiO2 addition in Salem Magnesite shows better densification compared to both as received Salem Magnesite and Salem Magnesite with Fe2O3 addition.

关键词： Sintering Additive Magnesite Densification

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A two-dimensional analytical-model-based comparative threshold performance analysis of SOI-SON MOSFETs

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Journal of Semiconductors 2011年第10期32卷 32-38页

作者： Sanjoy Deb Saptarsi Ghosh N Basanta Singh A K De Subir Kumar Sarkar department of Electronics&Telecommunication engineering Jadavpur University department of Electronics&Communication engineering Manipur Institute of Technology department of Electronics&Communication engineering National Institute of Technology

A generalized threshold voltage model based on two-dimensional Poisson analysis has been developed for SOI/SON *** short channel field effects,such as fringing fields,junction-induced lateral fields and substrate fields,are carefully investigated,and the related drain-induced barrier-lowering effects are incorporated in the analytical threshold voltage *** analytical model-based simulation,the threshold voltage roll-off and subthreshold slope for both structures are compared for different operational and structural parameter *** of analytical simulation are compared with the results of the ATLAS 2D physics-based simulator for verification of the analytical *** performance of an SON MOSFET is found to be significantly different from a conventional SOI *** short channel effects are found to be reduced in an SON,thereby resulting in a lower threshold voltage roll-off and a smaller subthreshold *** type of analysis is quite useful to figure out the performance improvement of SON over SOI structures for next generation short channel MOS devices.

关键词： silicon-on-insulator silicon-on-nothing Poisson's equation short channel effects threshold voltage roll-off subthreshold slope

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