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1.
Subrata Kumar Majumder Kamal ChandnaDhiren Sankar De Gautam Kundu 《International Journal of Mineral Processing》2006
Experiments were carried out to investigate the rheological properties of coal–oil–water suspension containing solids of different sizes. Two different coal samples with mean particle sizes of 120 mesh, 175 mesh and 220 mesh were used. The coal concentration was varied from 5% to 25% by weight. Sodium silicate has been used as an additive to study the behavior of the variation of average viscosity of the suspension. A generalized correlation has been developed to predict the average viscosity of suspension in terms of particle diameter of the coal, concentration of coal, viscosity of the suspending medium and the concentration of water. Experimental investigations revealed that coal–oil–water suspensions show an increase in the viscosity with decrease in coal size but with the addition of an additive, the average viscosity tends to decrease initially up to a certain optimum dosages and thereafter it increases with further addition of additives. Two empirical correlations are proposed for average viscosity of the coal–oil–water suspension, μsL in terms of physical properties of the solid and viscosity of the suspending medium with and without additives. 相似文献
2.
A large number of mineral processing equipment employs the basic principles of gravity concentration in a flowing fluid of a few millimetres thick in small open channels where the particles are distributed along the flow height based on their physical properties and the fluid flow characteristics. Fluid flow behaviour and slurry transportation characteristics in open channels have been the research topic for many years in many engineering disciplines. However, the open channels used in the mineral processing industries are different in terms of the size of the channel and the flow velocity used. Understanding of water split behaviour is, therefore, essential in modeling flowing film concentrators. In this paper, an attempt has been made to model the water split behaviour in an inclined open rectangular channel, resembling the actual size and the flow velocity used by the mineral processing industries, based on the Prandtl's mixing length approach. 相似文献
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In the present paper the intensity of serration of quartz grain boundary sutures in the Palaeoproterozoic age Malanjkhand
granite (Central India) is quantified using the ruler method of fractal analyses. The northern margin of the granite has proximity
to the Central Indian Suture (CIS) that forms the southernmost part of Central Indian Tectonic Zone (CITZ) along which amalgamation
of the northern and southern Indian shields took place. The fractal dimension (D) of the quartz sutures is calculated in 13
samples collected at varying distance from the CIS. D values are noted to increase in samples towards the CIS. This demonstrates
the influence of the tectonic events along the CIS on fabric development in the Malanjkhand granite. Magmatic fabric defined
by preferentially oriented feldspar laths and high-T solid-state deformation fabrics are observed in areas distant from the
CIS. In contrast, mylonites and low-T fabrics such as bulging quartz grain boundaries occur in proximity to the CIS. It is
inferred that the emplacement and high-T fabric development in the Malanjkhand granite was synchronous with regional accretionary
processes that occurred in the region during the Palaeoproterozoic. Two different possibilities, one involving a single tectonic
event and the other involving multiple tectonic events are discussed to explain the superimposition of low-T over high-T fabric
due to which intensity of quartz grain boundary serration increases towards the CIS. 相似文献
5.
Biosorption potential of Cedrus deodara sawdust (CDS) in terms of sorption of Zn(II) ion across liquid phase has been evaluated in the present investigation. The surface of the CDS biomass before the sorption of Zn(II) ions seemed to be more porous, non‐crystalline and heterogeneous. The maximum uptake capacity of CDS was 97.39 mg g?1. Sorption of Zn(II) ion on the surface of CDS sawdust was maximum at pH 5, temperature 45°C, initial concentration of Zn(II) ion 100 mg L?1, biomass dose 1 g L?1, contact time 150 min, and agitation rate 160 rpm. Pseudo second‐order kinetics with the highest linear regression coefficient (R2 = 0.99), and lowest values of error functions, i.e., chi (χ2) and sum of square errors (SSE) against pseudo first‐order rate kinetics showed that the sorption of Zn(II) ion on the surface of CDS was mediated by chemosoprtive forces of attraction rather than physical adsorption. Mechanistically, relatively higher proportion of sorption of Zn(II) ion in early phase of contact time was profoundly explained by Bangham's equation and film diffusivity (Df). Intraparticle or pore diffusion (Dp) of Zn(II) ion inside the pores of CDS was rate limiting step at the later stage of contact time. Furthermore, the thermodynamic study on sorption of metal ion delineated the fact that the Zn(II) sorption on the surface of CDS was spontaneous, endothermic together with increased entropy at solid liquid interface. 相似文献
6.
Sainath Aher Sambhaji Shinde Shantamoy Guha Mrinmoy Majumder 《Journal of Earth System Science》2017,126(2):21
An innovative approach for drought identification is developed using Multi-Criteria Decision Making (MCDM) and Artificial Neural Network (ANN) models from surveyed drought parameter data around the Dhalai river watershed in Tripura hinterlands, India. Total eight drought parameters, i.e., precipitation, soil moisture, evapotranspiration, vegetation canopy, cropping pattern, temperature, cultivated land, and groundwater level were obtained from expert, literature and cultivator survey. Then, the Analytic Hierarchy Process (AHP) and Analytic Network Process (ANP) were used for weighting of parameters and Drought Index Identification (DII). Field data of weighted parameters in the meso scale Dhalai River watershed were collected and used to train the ANN model. The developed ANN model was used in the same watershed for identification of drought. Results indicate that the Limited-Memory Quasi-Newton algorithm was better than the commonly used training method. Results obtained from the ANN model shows the drought index developed from the study area ranges from 0.32 to 0.72. Overall analysis revealed that, with appropriate training, the ANN model can be used in the areas where the model is calibrated, or other areas where the range of input parameters is similar to the calibrated region for drought identification. 相似文献
7.
This paper is an experimental investigation into the removal of arsenic species from simulated groundwater by adsorption onto Ca2+ impregnated granular activated carbon (GAC‐Ca) in the presence of impurities like Fe and Mn. The effects of adsorbent concentration, pH and temperature on the percentage removal of total arsenic (As(T)), As(III) and As(V) have been discussed. Under the experimental conditions, the optimum adsorbent concentration of GAC‐Ca was found to be 8 g/L with an agitation time of 24 h, which reduced As(T) concentration from 188 to 10 μg/L. Maximum removal of As(V) and As(III) was observed in a pH range of 7–11 and 9–11, respectively. Removal of all the above arsenic species decreased slightly with increasing temperature. The presence of Fe and Mn increased the adsorption of arsenic species. Under the experimental conditions at 30°C, the maximum percentage removals of As(T), As(III), As(V), Fe, and Mn were found to be ca. 94.3, 90.6, 98.0, 100 and 63%, respectively. It was also observed that amongst the various regenerating liquids used, a 5 N H2SO4 solution exhibited maximum regeneration (ca. 91%) of the spent GAC‐Ca. 相似文献
8.
The surface of the bacterial cells before the biosorption of Zn(II) ion has been found rough, heterogeneous, and non‐crystalline together with tremendous protrusions and negatively charged functional groups. The bacterium was characterized as rod shaped with Gram‐negative type of cell wall structure. In reaction dynamics, pseudo‐second‐order kinetics with higher linear correlation coefficient (R2) ranging between 0.97 and 0.99, lower sum of square errors (SSE) (0.035–0.081) and chi (χ2) (0.0013–0.009) provided a better explanation of sorption of Zn(II) ion on bacterium surface as compared to pseudo‐first‐order model. The removal of Zn(II) was governed by both film and intra‐particle diffusion at onset and later stage of sorption of metal ion on the surface of bacterial cells. The R2 (0.92–0.94) for intra‐particle diffusion model was quite higher with lower values of SSE (9.56–16.33) and chi (χ2) (11.26–19.65) against the Bangham's model. The positive value of ΔH (16.628 × 10?6 kJ/mol) and ΔS (5320.90 kJ/mol/K) showed that the biosorption of Zn(II) ion across liquid phase on bacterial surface was endothermic with increased randomness at solid–liquid interface. The negative values of ΔG demarcated the whole process as spontaneous in nature. In the present work, the distribution coefficient was found to be > 0.5 at various temperature ranges. At the attainment of equilibrium, the residual concentration of Zn(II) ion in liquid phase was around 0.6 mg/L, which was much below the limit described by United States Environmental Protection Agency (USEPA), i.e. 5 mg/L. 相似文献
9.
S. Kamsonlian S. Suresh V. Ramanaiah C. B. Majumder S. Chand A. Kumar 《International Journal of Environmental Science and Technology》2012,9(3):565-578
The present study deals with the biosorption of As(III) from aqueous solution using mango leaves powder (MLP) and rice husk (RH) in a batch operation. Scanning electron microscopy and Fourier transformation infrared spectrometry analysis shows the surface texture of biosorbents and metal binding of functional groups of before and after biosorption of As(III). The optimum pH was obtained at 7 and 6 with 7 and 6?g/l of dosage of MLP and RH, respectively. The adsorption of As(III) onto MLP and RH was favourably influenced by an increase in temperature. Equilibrium data were well represented by the Freundlich isotherm model. Nitric acid and ethylenediaminetetra acetic acid was found to be a better eluant for the desorption followed by hydrochloric acid and sodium hydroxide of As(III) with a maximum desorption efficiency of 69.5, 48.5 and 79.4, 86.3?%, respectively. The pseudo-second-order kinetic model was found to best fitted of the experimental data over the equilibrium time at 32?h. The positive values of heat of adsorption (23.89?kJ/mol for MLP and 52.26?kJ/mol for RH) indicate the endothermic nature of the adsorption process. The thermodynamic study showed the spontaneous nature of the sorption of As(III) onto MLP and RH. 相似文献
10.
Ratan K. Majumder M. A. Halim B. B. Saha Reo Ikawa Toshio Nakamura Makoto Kagabu Jun Shimada 《Environmental Earth Sciences》2011,64(5):1343-1352
A total number of 328 groundwater samples are analysed to evaluate the groundwater flow systems in Bengal Delta aquifers,
Bangladesh using environmental isotope (2H, 18O, 13C, 3H, and 14C) techniques. A well-defined Local Meteoric Water Line (LMWL) δ2H = 7.7 δ18O + 10.7 ‰ is constructed applying linear correlation analyses to the monthly weighted rainfall isotopic compositions (δ18O and δ2H). The δ18O and δ2H concentrations of all groundwater samples in the study area are plotted more or less over the LMWL, which provides compelling
evidence that all groundwaters are derived from rainfall and floodwater with a minor localized evaporation effects for the
shallow groundwaters. Tritium concentration is observed in 40 samples out of 41 with values varying between 0.3 and 5.0 TU,
which represents an evidence of young water recharge to the shallow and intermediate aquifers. A decreasing trend of 14C activity is associated with the heavier δ13C values, which indicates the presence of geochemical reactions affecting the 14C concentration along the groundwater flow system. Both vertical and lateral decrease of 14C activity toward down gradient show the presence of regional groundwater flow commencing from the unconfined aquifers, which
discharges along the coastal regions. Finally, shallow, intermediate, and deep groundwater flow dynamics has revealed in the
Bengal Delta aquifers, Bangladesh. 相似文献