CFD Simulation Studies on a 19 Cone Angle Hydrocyclone

Hydrocyclone being in practice for classification applicat-ions are of low cone angle typically at 10°. The details on the simulation of such hydrocyclone are well reported. The present study is an attempt to simulate the water flow behaviour inside a 3 inch 19° cone angle hydrocyclone, which in general is applied for processing intermediate size coal and is popularly know as heavy medium cyclone. A 3D axi-symmetric model of standard 3" heavy medium cyclone geometry is generated. The computational domain is divided into unstructured grid having 115053 tetrahe-dral volumes using GAMBIT preprocessor. A segregated solver with steady state 3-D double precision scheme was used for model computations assigning a convergence value of 1e-06. For predicting swirling flow characteristics prevailing inside the cyclone, Pressure Interpolation Scheme (PRESTO) is used. Reynolds stress model (RSM), which was reported to account with greater precision for the effects of swirl, rotation etc. was selected for turbulence calculat-ions. For obtaining the pressure field inside the system SIMPLE algorithm scheme was used. Higher-order Quadratic Upwind Interpolation (QUICK) spatial discretisation scheme was used for field variables interpolation from cell centers to faces of the control volumes. Tangential, axial velocity profiles and pressure distributions are pres-ented and the water-split values obtained through simula-tion are compared with the experimental results

CFD Analysis of Water Flow Behaviour Inside a Falcon Bowl

In mineral processing, techniques like classification; gravity concentration, thickening etc. require extensive understanding on fluid flow characteistics and relative movement of solids in fluids. The complexities in the geometries of the individual operations along with variable feed characteristics and limited computational facilities forced the researchers to optimize the performance through empirical. Though they are very useful in the mineral industry for a long time, better insight on the process physics can be achieved through computational based fluid dynamics modeling, design and simulation. Out standing developments in the computational facilities in the recent past have opened up avenues for process design and simulation through these techniques. The present study is an attempt to simulate the mechanism of water flow inside a rotating Falcon Concentrator bowl using a commercially available CFD package Fluent

Performance Evaluation of Water-Injection Cyclone Treating a Synthetic Mixture

The effect of change in operating variables i.e., vortex finder diameter,spigot diameter nd water injection rate on different performance numbers is studied in water-injection cyclone treating a synthetic mixture of atomized Ferro-silicon and ground silica sand. Suitable empirical models relating the operating variables and fines (below 25 microns) recovery, ferro-silicon and silica recoveries in the overflow productand the separation efficiency at 25 microns size are developed. At comparable levels of ope-rating throughput, the performance numbers obtained in a 100mm water-injection cyclone and a 100mm normal hydro- cyclone are discussed. An overall fines recovery of 85.6% was obtained in the overflow product of water-injection cyclone whereas in a normal hydrocyclone the combined fines recovery in the overflow product was 46.2%. Similarly the ferro-silicon recovery at fines below 25 microns in the overflow product from water-injection cyclone was 55.5% while that of hydro-cyclone was only 9.8%. Also, silica recovery at fines below 25 microns in the overflow product of a water-injection cyclone was 98.6% in comparison to 82.1% in a normal hydrocyclone. Separation efficiency values obtained between coarse and fine products at 25 microns in the overflow product of water-injection cyclone and hydro-cyclone were 83.5% and 45.8% respectively which indicates sharper classification in water-injection cyclone

Characterization Studies on Lead-Zinc Tailings from Rampura-Agucha Mines

The process tailings of base metal industries contain considerable amounts of acid generating 'pyrite and sul-fides of other minerals. The recovery of sulfide minerals from the tailings not only will have environmental advan-tage but will also result in conservation of mineral wealth.For any such recovery activity, it is essential to characterize the tailings for physical, chemical and mineralogical characteristics. In the present study, typi-cal lead-zinc tailings sample from the operating plant at Rampura-Agucha mines of Hindustan Zinc Limited was collec-ted and characterized for size distribution, size by size chemical composition and mineral phase analysis through X-ray diffraction method. The size-by-size metal contents indicated increasing levels of silver and pyrite with decreasing particle size and the lead and zinc bearing minerals are segregated at relatively coarser size fract-ions. Microscopic studies of the coarser fractions have indicated that the lead and zinc minerals are in unliber-ated form. The XRD study has indicated that quartz is the major mineral phase followed by pyrite, sphalerite, galena and silver. The overall tailings sample was found to cont-ain 19.41% of pyrite, 2.02 % of zinc, 0.69 % lead, and 26.94 ppm of silver contents

MGS Studies for Recovering Iron and Silver Values from Lead-Zinc Tailings

In mineral processing plants valuable minerals are recovered by rejecting gangue materials through various physical processing techniques to produce high-grade concentrate. However, after processing these ores, the tailings generated contain considerable amount of valua-bles because of inefficient of process plant or due to fluctuations in the mineralogical composition of the ore. Therefore, recovery of these valuable minerals is prerequisite from environmental and mineral conservation point of views

Effectiveness of 0.125% Bupivacaine versus 0.125% Ropivacaine in Epidural Labour Analgesia- A Randomised Clinical Study

Introduction: Epidurally administered local anaesthetics provide most effective analgesia during labour process. Among the available local anaesthetics, bupivacaine and ropivacaine are the most commonly used drugs in concentrations ranging from 0.0625% to 0.125% and 0.08% to 0.125%, respectively. Both these drugs are weak bases, highly protein-bound, highly lipid soluble, and have a pKa of 8.1, low unionised fraction, thus, having a slightly longer time for onset of action but with a longer duration of action and have less transfer across the placenta. Hence, they are ideal drugs for use in labour analgesia. Aim: To compare the effectiveness of programmed intermittent bolus of 0.125% bupivacaine vs 0.125% ropivacaine in low volumes in full term primigravidas for epidural labour analgesia. Materials and Methods: This randomised clinical study was conducetd at PES Institute of Medical Sciences and Research, Kuppam, Andhra Pradesh, India, between June 2020 and December 2021 among 80 full-term primi parturients requiring normal vaginal delivery. They were randomly divided into two groups of 40 each. Group B received 10 mL of 0.125% bupivacaine and group R received 10 mL of 0.125% ropivacaine as initial bolus dose. Repeat doses of 5 mL was given every 60 minutes or when the patient had Visual Analogue Score (VAS) score >4 with a maximum dose of 10 mL/hr with a 20 minute interval between two doses. Parameters assessed were onset, duration, level and quality of analgesia, motor blockade, number of epidural top ups, total volume of drug consumed, mode of delivery, duration of labour, APGAR score, haemodynamics, patient satisfaction and complications. Data was entered in Microsoft Excel 2010 version and analysed using Statistical Package for Social Sciences (SPSS) version 20.0. Results: Both drugs were equally effective in terms of analgesia, maternal and foetal outcomes. Bupivacaine had a faster onset of action (7.075±0.916 min) compared to ropivacaine (8.225±0.891 min) (p-value=0.001). Ropivacaine had a shorter duration of action (43.1±2.30 min vs 47.9±4.16 min in group B) (p-value=0.0001), requiring more top-up doses (5.2±0.46 vs 4.77±0.61 in group B) (p-value=0.0007), and more total volume of drug (38.5±3.08 mL vs 35.5±4 mL in group B) (p-value=0.002). It also caused lesser motor blockade (Bromage score of 1 in 1 parturient vs 8 parturients in group B) (p-value=0.0129) and better overall maternal satisfaction score (excellent) in 30 parturients vs 25 parturients in group B. APGAR scores at 1 minute and 5 minutes were comparable between the two groups. Mean heart rates, mean blood pressures were also comparable between the two groups. There were no significant adverse effects in either groups. Conclusion: By providing minimal motor blockade and adequate analgesia 0.125% ropivacaine allows parturients to go through the labour process with excellent maternal satisfaction and minimal adverse effects compared to 0.125% bupivacaine

Classification of Ultra Fine Particles from Fly Ash

The annual generation of coal combustion residue in the country is 110 MT. The generation of coal combustion residue is expected to increase with ever increasing demand for power. Management of this solid waste has been a great concern to the nation. Most of the reports on utilization of coal combustion residue are limited to direct usage of the material or selective collection from ESP fields in the thermal power plants. In this connection several efforts are being made in the country to enhance its application as a replacement to cement, soil modifier, roads and embankments etc. Very little or no research attempts are made in understanding the appropriate compo-nents which results in beneficial properties and value added products. Fly ash in very fine size range exhibits spherical morphological characteristics and thus acts as good fillers in rubber and polymer compounds. However, recovery of this size material from the bulk is yet a challenge in the process industry as the material forms clusters at very fine sizes. The present study is an atte-mpt to beneficiate fly ash to obtain material with an average particle size around 5 microns. A cyclone separa-tor, which employs very high g* forces for separation of particles is employed for achieving the separation. At this high g* forces, the declustering of particles is observed. This technique has generated product with an average particle size (ds& between 4 to 8 microns. The results obtained at different test runs are discussed

An Economic Analysis of Pigeonpea Seed Production Technology and Its Adoption Behavior: Indian Context

The present study was based on primary data collected from 100 farmers in Gulbarga district of Karnataka, India, during the agricultural year 2013-2014. Study shows that average land holding size of pigeonpea seed farmers was higher in comparison to grain farmers and district average. The study illustrates a ratio of 32 : 68 towards fixed and variable costs in pigeonpea certified seed production with a total cost of ₹ 39436 and the gross and net returns were ₹ 73300 and ₹ 33864 per hectare, respectively. The total cost of cultivation, gross return, and net return in pigeonpea seed production were higher by around 23, 32, and 44 percent than grain production, respectively. Hence, production of certified seed has resulted in a win-win situation for the farmers with higher yield and increased returns. The decision of the farmer on adoption of seed production technology was positively influenced by his education, age, land holding, irrigated land, number of crops grown, and extension contacts while family size was influencing negatively. Higher yield and profitability associated with seed production can be effectively popularized among farmers, resulting in increased certified seed production

INCOIS-Real time Automatic Weather Station(IRAWS) dataset - Quality control and significance of height correction

The INCOIS-Real time Automatic Weather Station(IRAWS) program was started in the year 2009 and was first installed onboard ORV Sagar Nidhi. Currently, there are 36 ships carrying IRAWS setup. Apart from storing one minute observations in the log onboard the ship, hourly averaged observations are reported through INSAT satellite communication. This report briefs about the hourly dataset of IRAWS and its quality control. In this report, QC results of SST and all meteorological parameters except radiation parameters is discussed. Specific quality check was applied to wind speed (WS) and sea surface temperature (SST) observations. The WS observations measured onboard few ships had a dimensional correction and SST was observed only on few ships. As SST observations are required to compute meteorological variables like DBT, RH, WS to standard height of 10 m, level-3 dataset of AVHRR SST was utilized in place of IRAWS SST wherever the data is found to be faulty. On similar terms bias correction could not be applied to IRAWS SST with the help of AVHRR SST as the error in SST observations are due to the failure of sensor. However all those IRAWS SST observations that passed the QC check were observed to be of high quality and have a correlation coefficient of 0.5 with AVHRR SST and is significant at 95% significant level. Apart from SST and radiation observations, all other parameters observations are found out to be of good quality with 70 to 90 QC pass percentage . Apart from the details of QC check, significance of representing climate variable at a homogeneous standard height is also shown in this repor

Seed Longevity in Legumes: Deeper Insights Into Mechanisms and Molecular Perspectives

Sustainable agricultural production largely depends upon the viability and longevity of high-quality seeds during storage. Legumes are considered as rich source of dietary protein that helps to ensure nutritional security, but associated with poor seed longevity that hinders their performance and productivity in farmer's fields. Seed longevity is the key determinant to assure proper seed plant value and crop yield. Thus, maintenance of seed longevity during storage is of prime concern and a pre-requisite for enhancing crop productivity of legumes. Seed longevity is significantly correlated with other seed quality parameters such as germination, vigor, viability and seed coat permeability that affect crop growth and development, consequently distressing crop yield. Therefore, information on genetic basis and regulatory networks associated with seed longevity, as well as molecular dissection of traits linked to longevity could help in developing crop varieties with good storability. Keeping this in view, the present review focuses towards highlighting the molecular basis of seed longevity, with special emphasis on candidate genes and proteins associated with seed longevity and their interplay with other quality parameters. Further, an attempt was made to provide information on 3D structures of various genetic loci (genes/proteins) associated to seed longevity that could facilitate in understanding the interactions taking place within the seed at molecular level. This review compiles and provides information on genetic and genomic approaches for the identification of molecular pathways and key players involved in the maintenance of seed longevity in legumes, in a holistic manner. Finally, a hypothetical fast-forward breeding pipeline has been provided, that could assist the breeders to successfully develop varieties with improved seed longevity in legumes