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Srinivas K.,Uranium Corporation of India Ltd | Sekhar D.M.R.,Jordan Phosphate Mines Company Ltd
Indian Chemical Engineer | Year: 2010

Soaps of mixed fatty acid origin or soap-light diesel oil (LDO) emulsion are used as collectors in the froth flotation of salt type minerals (for example - apatite, fluorite, dolomite, etc.). Detergents are sometimes used along with soaps to reduce the consumption of soap and also to improve the process efficiency. In the present investigations effect of different reagent regimes on flotation of a siliceous phosphate ore was studied. Flotation tests were carried out using mixed fatty acid soap and tall oil. Both the reagents were used as emulsions with light diesel oil in the ratio of 1:1.2. Tests were also carried out with promoters (Alfa Olefin Sulfonate [AOS], Linear Alkyl Benzene Sulfonate [LABS] and Urea) along with these reagents to evaluate the process efficiency. While AOS and LABS are detergents, urea is a polar non electrolyte reagent known to act as hydrotrope. It is noted that mixed fatty acid soap-LDO emulsion (SL emulsion) shows better process efficiency than tall oil-LDO emulsion (TL emulsion). The highest recoveries (<90%) were achieved when mixed fatty acid was used in conjunction with promoters. The experiments with promoters yielded higher recoveries rather than mixed fatty acid or tall oil used alone. © 2010 Copyright Indian Institute of Chemical Engineers.

Panigrahi D.C.,Indian School of Mines | Mishra D.P.,Indian School of Mines | Sahu P.,Indian School of Mines | Bhowmik S.C.,Uranium Corporation of India Ltd
Annals of Nuclear Energy | Year: 2015

Monitoring of radiological parameters in underground uranium mines is essential to maintain the radiation levels within safe limits. In this study, the radiological parameters such as external gamma emitted from ore body, long-lived alpha activity associated with ore dust and radon concentration in an operating underground uranium mine located at Jaduguda, India were measured using different equipments such as micro-R radiation survey meter, personal air sampler and scintillation cell. The geometric mean values of external gamma radiation level, long-lived alpha activity, radon activity concentration and equilibrium equivalent radon (EER) concentration were found to be 2.39 μGy h-1, 16.84 mBq m-3, 872.89 Bq m-3 and 436.44 Bq m-3 respectively with their geometric standard deviations of 1.56, 3.21, 1.58 and 1.58. The total radiation dose received by the miners estimated from the radiological parameters was found to be well below the prescribed limit of 20 mSv y-1 recommended by International Commission on Radiation Protection (ICRP), and hence, it may not pose significant health hazards to the Jaduguda miners. ©2014 Elsevier Ltd. All rights reserved.

Maurya V.P.,Indian School of Mines | Bhattacharya B.B.,se National Center for Basic science | Adhikari P.K.,Uranium Corporation of India Ltd | Das L.K.,New Garia Co operative Housing Society
Journal of Applied Geophysics | Year: 2015

The regional magnetotelluric (MT) survey across Dalma Volcanics (DVs) in North Singhbhum Mobile Belt (NSMB) was carried out to obtain the conductivity model and to understand the metallogeny. The structure in general is 2-D and the average strike is N60°W. 2-D inversions using TE + TM and TE + TM + Tzy were carried out. Both inversions derived models with similar features but with modified shape. The TE + TM + Tzy inversion brings up two conducting zones enveloping three anomalous conducting bodies. Inductively coupled plasma atomic emission spectroscopy (ICP-AES) analysis of the samples collected from 8 to 10. m pit from different stratigraphic units of Dalma volcano-sedimentary belt indicates the presence of gold, silver, uranium and copper. The study area is a felsic dominated rifted margin and shows high conductivity contrast along with high gravity, magnetic and significant radiometric anomaly. Thus, the conducting zones indicate the presence of volcanogenic massive sulfide (VMS) or volcano hosted gold deposit (Au-VMS) in NSMB. © 2015 Published by Elsevier B.V.

Pal D.C.,Jadavpur University | Sarkar S.,Jadavpur University | Mishra B.,Indian Institute of Technology Kharagpur | Sarangi A.K.,Uranium Corporation of India Ltd
Journal of Earth System Science | Year: 2011

The Jaduguda U (-Cu-Fe) deposit in the Singhbhum shear zone has been the most productive uranium deposit in India. Pyrite occurs as disseminated grains or in sulphide stringers and veins in the ore zone. Veins, both concordant and discordant to the pervasive foliation, are mineralogically either simple comprising pyrite ± chalcopyrite or complex comprising pyrite + chalcopyrite + pentlandite + millerite. Nickel-sulphide minerals, though fairly common in concordant veins, are very rare in the discordant veins. Pyrite in Ni-sulphide association is commonly replaced by pentlandite at the grain boundary or along micro-cracks. Based on concentrations of Co and Ni, pyrite is classified as: type-A - high Co (up to 30800 ppm), no/low Ni; type-B - moderate Co (up to 16500 ppm) and moderate to high Ni (up to 32700 ppm); type- C - no/low Co and high Ni (up to 43000 ppm); type-D - neither Co nor Ni. Textural and compositional data of pyrites suggest that the hydrothermal fluid responsible for pre-/early-shearing mineralization evolved from Co-rich to Ni-rich and the late-/post-shearing fluid was largely depleted in minor elements. Sulphur isotope compositions of pyrite mostly furnish positive values ranging between -0.33 and 12.06‰ Composite samples of pyrites with only type-A compositions and mixed samples of type-A and type-B are consistently positive. However, pyrite with mixed type-A and type-C and pyrite with type-D compositions have negative values but close to 0‰ By integrating minor element and sulphur isotope compositions of pyrite in conjunction with other published data on the Jaduguda deposit, it is proposed that reduced sulphur for the precipitation of most pyrites (type-A, type-B) was likely derived from isotopically heavy modified seawater. However, some later sulphur might be magmatic in origin remobilized from existing sulphides in the mafic volcanic rocks in the shear zone. © Indian Academy of Sciences.

Abhilash,Indian National Metallurgical Laboratory | Pandey B.D.,Indian National Metallurgical Laboratory | Singh A.K.,Uranium Corporation of India Ltd
Energy Procedia | Year: 2013

Uranium ore from the Narwapahar mines, Jharkhand, India (∼0.047% U 3O8), rich in apatite content (5%) was investigated for bio-processing in lab-scale columns and bioreactor. With a load of 2.0 kg ore in column at pH 1.7 using A. ferrooxidans and L. ferrooxidans, uranium recovery of 57% and 66% was achieved, respectively in 40 days in comparison to 39% in chemical leaching. Bio-leaching studies with the Narwapahar ore carried out in a 2L bioreactor at 10% (w/v) pulp density at pH 2.0, rpm 150 and 35°C yielded 57% and 63% uranium recovery by 10% (v/v) enriched culture of A. ferrooxidans and L. ferrooxidans, respectively in 5 days. In another set of experiments, biogenic ferric sulfate generated in the bioreactor was mixed with the ore slurry and 90.3% uranium biorecovery was achieved in 10h at pH 2.0, 20% (w/v) pulp density of <45μm particles and 40°C with L. ferrooxidans as against 87% leaching at 35°C with A. ferrooxidans. © 2013 The Authors.

Pal D.C.,Jadavpur University | Chaudhuri T.,Jadavpur University | McFarlane C.,University of New Brunswick | Mukherjee A.,Jadavpur University | Sarangi A.K.,Uranium Corporation of India Ltd
Economic Geology | Year: 2011

The present study combines textures, compositions, and in situ dating of allanite and whole-rock geochemistry from the Bagjata uranium deposit in the Singhbhum shear zone, the most important uranium-producing belt in India, to investigate the chemical evolution of rare earth element (REE) mineralization. Allanite, volumetrically the most important sink of light rare earth elements (LREEs) in this deposit, occurs as disseminated grains, pockets, veins, and stringers in biotite schist and chlorite schist. Metasomatic addition of LREEs in the rock was associated with Ca-K-Fe ± B metasomatism, as evident from the vein mineralogy. The allanite-bearing metasomatized rocks are locally extremely enriched in REEs, reaching up to ∼4.8 wt percent ∑REEs. The textures and compositions of allanite demonstrate that early REE-rich allanite was replaced by later, relatively less REE bearing allanite-epidote, and this alteration followed a substitution scheme of REE+3 + (Fe +2, Mg+2) → Ca+2 + (Al, Fe+3). The presence of halite-bearing fluid inclusions in associated tourmaline, high Cl content of biotite, and other circumstantial evidence indicate that a high-salinity, Cl-rich fluid was likely responsible for initial LREE metasomatism. A later hydrothermal event altered preexisting allanite and removed REEs. The more oxidized nature of altered allanite and the presence of unidentified secondary REE minerals in association with sulfide might indicate the involvement of oxidized, sulfate-rich fluid in the alteration of allanite and the removal of REEs. Alternatively, fluoride complexing of REEs and selective removal of HREEs during this alteration are possible. In situ laser ablation-inductively coupled plasma-mass spectrometry (LA-ICP-MS) U-Pb dating of allanite and monazite indicates that LREE metasomatism took place at ∼1.88 Ga. The next hydrothermal event, which altered existing allanite, removed some REEs, and perhaps was associated with U (+HREE) addition, is dated at ∼1.66 Ga. The youngest age determined from the thin rim of allanite is ∼1.02 Ga. These three different ages, determined from allanite, overlap with the known thermotectonic events in and around the Singhbhum shear zone. Comparison between the calculated ∑REE content of allanite-rich rock prior to allanite alteration and whole-rock ∑REE composition of the same rock suggests that the addition of a large quantity of REEs was followed by significant REE removal. Strong variations in the modal abundances of the constituent minerals and in whole-rock compositions, including REEs, indicate open-system behavior. The whole-rock REE pattern suggests that decoupling between LREEs and HREEs might be possible during superimposed alteration. Therefore, petrogenetic modeling using an REE-based discrimination diagram and REE patterns should be done with caution for rocks that underwent multiple events of hydrothermal fluid flux. © 2011 Society of Economic Geologists, Inc.

Sarangi S.N.,Institute of Physics, Bhubaneswar | Adhikari P.K.,Uranium Corporation of India Ltd | Pandey D.,Banaras Hindu University | Sahu S.N.,Institute of Physics, Bhubaneswar
Journal of Nanoparticle Research | Year: 2010

CdSe nanocrystalline thin films have been synthesized on indium tin oxide (ITO) substrates by an electrodeposition technique. A Schottky junction device in the configuration, ITO/nano-CdSe/Au has been fabricated to study the device interface properties by current (I)-voltage (V) and capacitance (C)-voltage (V) measurements and compared with the ITO/bulk-CdSe/Au device. The I-V characteristics of the nano-CdSe device shows a series resistance effect and C-V characteristics show the presence of surface/interface traps induced by a thin native oxide layer at the nano-CdSe/Au interface and is responsible to the deviation in the ideal Mott-Schottky behavior. The presence of a thin oxide layer on the CdSe nanocrystal surface has been identified from Rutherford backscattering (RBS) spectrometry. The low frequency capacitance response of the nano-CdSe device characteristics are being compared with the bulk device, which confirms the presence of surface/interface states within the band gap of CdSe nanocrystals. Mott-Schottky plots at different frequencies indicate the formation of a Schottky barrier between nano-CdSe and Au junction. © 2009 Springer Science+Business Media B.V.

Abhilash,Indian National Metallurgical Laboratory | Mehta K.D.,Indian National Metallurgical Laboratory | Kumar V.,Indian National Metallurgical Laboratory | Pandey B.D.,Indian National Metallurgical Laboratory | Tamrakar P.K.,Uranium Corporation of India Ltd
Mineral Processing and Extractive Metallurgy Review | Year: 2010

The bioleaching of a low-grade Indian uraninite ore (triuranium octoxide, U3O8: 0.024%), containing ferro-silicate and magnetite as the major phases, and hematite and pyrite in minor amounts, has been reported. Experiments were carried out in laboratory scale column reactors inoculated with enriched culture of Acidithiobacillus ferrooxidans isolated from the source mine water. The pH effect on uranium recovery was examined with the same amounts of ores in different columns. With the presence of 10.64% Fe in the ore as ferro-silicate, the higher uranium biorecovery of 58.9% was observed with increase in cell count from 6.4×107 to 9.7×108 cellslmL at pH 1.7 in 40 days as compared to the uranium recovery of 56.8% at pH 1.9 with a corresponding value of 9.4×108 cellslmL for 2.5-kg ore in the column. The dissolution of uranium under chemical leaching conditions, however, recorded a lower value of 47.9% in 40 days at room temperature. Recoveries were similar with 6-kg ore when column leaching was carried out at pH 1.7. The bioleaching of uranium from the low-grade ore of Turamdih may be correlated with the iron(II) and iron(III) concentrations, and redox potential values. © 2010 Taylor & Francis Group, LLC.

Abhilash,Indian National Metallurgical Laboratory | Mehta K.D.,Indian National Metallurgical Laboratory | Kumar V.,Indian National Metallurgical Laboratory | Pandey B.D.,Indian National Metallurgical Laboratory | Tamrakar P.K.,Uranium Corporation of India Ltd.
Energy Procedia | Year: 2011

Meeting the feed supply of uranium fuel in the present and planned nuclear reactors calls for huge demand of uranium, which at the current rate of production, shows a mismatch. The processing methods at UCIL (DAE) needs to be modified/ changed or re-looked into because of its very suitability in near future for low-index raw materials which are either unmined or stacked around if mined. There is practically no way to process tailings with still some values. Efforts were made to utilize such resources (low-index ore of Turamdih mines, containing 0.03% U3O8) by NML in association with UCIL as a national endeavor. In this area, the R&D work showed the successful development of a bioleaching process from bench scale to lab scale columns and then finally to the India's first ever large scale column, from the view point of harnessing such a processing technology as an alternative for the uranium industry and nuclear sector in the country. The efforts culminated into the successful operation of large scale trials at the 100kg and 2ton level column uranium bioleaching that was carried out at the site of UCIL, Jaduguda yielding a maximum recovery of 69% in 60 days. This achievement is expected to pave the way for scaling up the activity to a 100ton or even more heap bioleaching trials for realization of this technology, which needs to be carried out with the support of the nuclear sector in the country keeping in mind the national interest. © 2011 Published by Elsevie Ltd.

Gupta R.,Uranium Corporation of India Ltd. | Sarangi A.K.,Uranium Corporation of India Ltd.
Energy Procedia | Year: 2011

India's atomic energy programme, in spite of opportunities for import of fuel shall continue to prefer the ideal path of generating power using indigenous uranium. In the last four decades, the Indian uranium industry has established mining and processing capacity of 5,500 tpd ore which is likely to go up to 12,000 tpd by 2015. The grade of uranium ore in India being low, inevitable efforts to mine and process progressive lower grade ore does not record matching rise in uranium production capacity. The SE part of Cuddapah basin is likely to draw greater attention for mining of carbonate hosted rock in coming decade. Successful implementation of indigenously developed processing technology at Tummalapalle holds the key for larger expansion programme of uranium production capability in this area. Further e xpansion of uranium production capacity shall greatly depend on the progress made on mining and processing of ore reserves in Northern part of Cuddapah basin (Andhra Pradesh) lying in environmentally sensitive regions and sandstone hosted deposits of Meghalaya around Kyelleng Pyndengsohiong. The technologies to mine thin and low grade ore, benchmark of zero discharge, higher and purer product recovery, disposal and management of large tailings, public perception on uranium mining, availability of skilled manpower etc are expected to be the major challenges for indigenous uranium production scenario in coming decades. 2010 Published by Elsevier Ltd.

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