scholarly journals Semi-Continuous Froth Discharge to Reduce Entrainment of Fine Particles in Flotation Cells Subject to Low-Mineralized Froths

Minerals ◽  
2020 ◽  
Vol 10 (8) ◽  
pp. 695
Author(s):  
Juan Yianatos ◽  
Paulina Vallejos ◽  
Luis Vinnett ◽  
Sebastián Arriagada
Keyword(s):  
Experimental Data ◽  
Fine Particles ◽  
Continuous Mode ◽  
Transient Model ◽  
Operational Strategy ◽  
Flotation Cells ◽  
Metallurgical Performance ◽  
Good Potential ◽  
Loading And Unloading ◽  
Concentrate Grade

An operational strategy is proposed to improve the metallurgical performance of flotation cells subject to low-mineralized froths. This strategy consists of using a semi-continuous discharge into the concentrate, in which the froth is operated under loading and unloading periods. A transient model is developed to evaluate the proposed approach. The model is calibrated using experimental data from two industrial flotation banks. The metallurgical performances of the last cells of these banks are then simulated, considering the semi-continuous froth discharge. The results show that the semi-continuous mode significantly reduces gangue entrainment, improving the concentrate grade while maintaining approximately the same recovery. The semi-continuous strategy demonstrates good potential to enhance the metallurgical indexes under low-mineralized froths, as those in the last cells of rougher flotation banks.

CH4 Direct Reduction of In-Flight Fe3O4 Concentrate Particles

2018 ◽  
Vol 14 (1) ◽  
Author(s):  
Bahador Abolpour ◽  
M. Mehdi Afsahi ◽  
Ataallah Soltani Goharrizi
Keyword(s):  
Experimental Data ◽  
Mathematical Model ◽  
Fine Particles ◽  
Direct Reduction ◽  
Constant Heat Flux ◽  
Constant Heat ◽  
Dynamic Motion ◽  
Magnetite Ore ◽  
Model Predictions ◽  
Kinetics Of

Abstract In this study, reduction of in-flight fine particles of magnetite ore concentrate by methane at a constant heat flux has been investigated both experimentally and numerically. A 3D turbulent mathematical model was developed to simulate the dynamic motion of these particles in a methane content reactor and experiments were conducted to evaluate the model. The kinetics of the reaction were obtained using an optimizing method as: [-Ln(1-X)]1/2.91 = 1.02 × 10−2dP−2.07CCH40.16exp(−1.78 × 105/RT)t. The model predictions were compared with the experimental data and the data had an excellent agreement.

Buckling of Viscoelastic Columns. Part II: Constant Deformation Rate Buckling

1985 ◽  
Vol 58 (1) ◽  
pp. 164-175 ◽  
Author(s):  
Shau-Chew Wang ◽  
Eberhard A. Meinecke
Keyword(s):  
Experimental Data ◽  
Secondary Structure ◽  
Carbon Black ◽  
Deformation Rate ◽  
Linear Viscoelasticity ◽  
Theoretical Development ◽  
Gravitational Effects ◽  
Loading And Unloading ◽  
Constant Deformation ◽  
Lower Carbon

Abstract The buckling of viscoelastic columns has been considered from both a theoretical and an experimental perspective. The fact that buckling occurs at relatively low strain where the SBR is nearly linearly viscoelastic allowed several simplifications in the theoretical development, leading to closed form predictions of the loading and unloading curves. This treatment neglects gravitational effects and carbon secondary structure effects and fits the experimental data best at HAF loadings around 30 phr. At lower carbon black loadings, the gravitational effects caused the experimental Euler load to be less than predicted from linear viscoelasticity theory, while at higher carbon black loadings, the carbon black structure led to higher Euler loads than predicted.

A CFD Study of Existing Drag Models for Geldart A Particles in Bubbling Fluidized Beds

2014 ◽  
Author(s):  
Bahareh Estejab ◽  
Francine Battaglia
Keyword(s):  
Experimental Data ◽  
Fluidized Beds ◽  
Fine Particles ◽  
The Other ◽  
Particle Interactions ◽  
Model Group ◽  
Drag Model ◽  
Numerical Studies ◽  
Solid Phases ◽  
Drag Models

In this study, seven drag models are examined to determine how they affect fluidization behavior of Geldart A particles of biomass and coal. Notwithstanding the notable number of numerical studies to find the best drag model for larger particles, there is a dearth of information related to drag models for finer Geldart A particles. Additionally, to our knowledge, these drag models have not been tested with a binary mixture of Geldart A particles. Computational fluid dynamics was used to model the gas and solid phases in an Eulerian-Eulerain approach to simulate the particle-particle interactions of coal-biomass mixtures and compare the predictions with experimental data. In spite of the previous findings that bode badly for using predominately Geldart B drag models for fine particles, the results of our study reveal that if static regions of mass in the fluidized beds are considered, these drag models work well with Geldart A particles. It was found that the seven drag models could be divided into two categories based on their performance. One category included the Gidaspow family of drag models (Gidaspow, Gidaspow-Blend, and Wen-Yu) and the Syamlal-O’Brien drag model; these models closely predicted the experiments for single solids phase fluidization. For binary mixtures, however, the other drag model group (BVK, HYS, Koch and Hill) yielded better predictions.

Three-Dimensional Modeling of Density Current in Confined and Unconfined Channels

2006 ◽  
Author(s):  
Ehsan Aram ◽  
Bahar Firoozabadi
Keyword(s):  
Experimental Data ◽  
Fine Particles ◽  
Experimental Studies ◽  
Three Dimensional ◽  
Velocity Profiles ◽  
Density Current ◽  
Three Dimensional Modeling ◽  
Small Width ◽  
Dimensional Modeling ◽  
Large Width

Dense underflows are continuous currents which move down-slope due to the fact that their density is heavier than that ambient water. In this work, 2-D and 3-D density current in a channel were investigated by a set of experimental studies and the data were used to simulate the density current. The velocity components were measured using Acoustic Doppler Velocimetry (ADV). The height of density current (current's depth) was also measured. In this study, the density current with a uniform velocity and concentration enters the channel via a sluice gate into a lighter ambient fluid and moves forward down-slope. A low-Reynolds number turbulent model (Launder and Sharma, 1974) has been applied to simulate the structure of 3-D density current in the confined (small width three dimensional density current) and unconfined (large width three dimensional density current) channels. The computed velocity profiles in unconfined channel were compared with the 3-D experimental data for verification. The height and velocity profiles of the confined current were also compared with 2-D experimental data. It was shown that by decreasing in width of the channel, the height of the current and the magnitude of maximum and average velocity increase and the confined current behaves as 2-D current after a distance. These factors prepare the conditions for minimizing sediment deposition and sedimentation rates can be greatly reduced. Although the k - ε Launder and Sharma model is applied here to a conservative density current, it seems that the analysis can be valid in general for turbidity current laden with fine particles.

Effect of the ageing on the dissipative properties of getinacks subjected to repeated static loading

2014 ◽  
Vol 11 (6) ◽  
pp. 589-596
Author(s):  
Valesyan Shant
Keyword(s):  
Experimental Data ◽  
Experimental Investigation ◽  
Temperature Field ◽  
Energy Dissipation ◽  
Hysteresis Loop ◽  
Static Loading ◽  
Applied Load ◽  
Effect Of Temperature ◽  
Loading And Unloading

The effect of ageing on the dissipative properties of getinacks subjected to repeated static loading has been investigated. Specimens were tested at the age of 1, 4, and 8 years. The approximation of experimental data is done, and the energy of dissipation is calculated. Based on the investigation of getinacks manufactured by the technology of regulated thermo-pressing, this technology can be recommended for the manufacturing of appropriate products.The results of experimental investigation of the effect of temperature field on the dissipative properties of layered getinacks widely applicable in electrical manufacturing, electronics and microelectronics are considered in this paper. The approximation of the experimentally obtained dependences between σ and ε for the loading (→) and unloading (←) parts of the hysteresis loop are calculated and plotted. The factor of energy dissipation is defined. Estimated that the temperature field affects the dissipative properties of the layered getinacks and that effect is depending on the value of applied load cyclically acting on the material.

Passive Cooling Measurements for a Concentrating Photovoltaic Array

1983 ◽  
Vol 105 (4) ◽  
pp. 413-417
Author(s):  
F. K. Deaver ◽  
M. W. Edenburn
Keyword(s):  
Heat Transfer ◽  
Experimental Data ◽  
Solar Cells ◽  
Heat Exchanger ◽  
Analytical Model ◽  
Passive Cooling ◽  
Transient Model ◽  
Photovoltaic Array ◽  
Definite Effect

Solar cells in a concentrating photovoltaic array absorb heat that must be removed. One method is to use a finned aluminum heat exchanger whose modeling requires estimating the coefficient of heat transfer from fins to surroundings; transfer depends on such parameters as windspeed and direction, and exchanger design. A transient analytical model has been constructed and applied to experimental data. Coefficients of heat transfer were calculated and correlated with windspeed and direction, which appear to have a definite effect on the overall coefficient. The transient model and apparent relationships between windspeed and convective coefficients are described.

An Improved Transient Model of Tool Temperatures in Metal Cutting

2000 ◽  
Vol 123 (1) ◽  
pp. 30-37 ◽  
Author(s):  
Tien-Chien Jen ◽  
Aloysius U. Anagonye
Keyword(s):  
Experimental Data ◽  
Heat Flux ◽  
Metal Cutting ◽  
Temperature Response ◽  
Iteration Process ◽  
Energy Partitioning ◽  
Tool Temperature ◽  
Transient Model ◽  
Initial Transient ◽  
Transient Energy

A model for predicting cutting tool temperatures under transient conditions is presented. The model of Stephenson et al. [10] is extended to include the initial transient response to the tool temperature and nonuniform heat flux distributions. The main goal in this paper is to be able to accurately predict the initial transient tool temperature response, or temperatures in interrupted cutting for cases where the cutting time is short. A method to predict the true transient energy partitioning instead of quasi-steady energy partitioning (Stephenson et al., [10]), without seeking the full numerical analysis, has been developed. In this paper, the transient energy partitioning is obtained through a fixed-point iteration process by modifying the quasi-steady energy partitioning method presented by Loewen and Shaw [11]. The predicted transient tool temperatures are compared quantitatively to the experimental data. Utilizing a semi-empirical correlation for heat flux distribution along the tool-chip interface, the temperature distribution is calculated and compared qualitatively to existing experimental data.

CFD Simulation of Slug Dissipation in an Enlarged Impacting Tee

2019 ◽  
Author(s):  
Mobina Mohammadikharkeshi ◽  
Mazdak Parsi ◽  
Ramin Dabirian ◽  
Ram S. Mohan ◽  
Ovadia Shoham
Keyword(s):  
Experimental Data ◽  
Void Fraction ◽  
Cfd Simulation ◽  
Petroleum Industry ◽  
Production Operation ◽  
Cfd Simulations ◽  
Ansys Fluent ◽  
Transient Model ◽  
Diameter Pipe ◽  
Computational Fluid Dynamics Cfd

Abstract Slug flow, which commonly occurs in the petroleum industry, is not always a desired flow pattern due to production operation problems it may cause in pipelines and processing facilities. To mitigate these problems, flow conditioning devices such as multiphase flow manifolds and slug catchers are used, where dissipation of slugs occurs in downward flow or in larger diameter pipe sections. Tee-junctions are important parts of these flow conditioning devices. In this work, Computational Fluid Dynamics (CFD) simulations are conducted using ANSYS/FLUENT 17.2 to investigate slug dissipation in an Enlarged Impacting Tee-Junction (EIT). An Eulerian–Eulerian MultiFluid VOF transient model in conjunction with the standard k-ε turbulent model is used to simulate slug dissipation in an EIT geometry. The EIT consists of a 0.05 m ID 10 m long inlet, which is connected to the center of a 0.074 m ID 5.5 m long section that forms the EIT branches. Moreover, experimental data are acquired on slug dissipation lengths in a horizontal EIT with a similar geometry as in the CFD simulations. The CFD results include the mean void fraction and cross-sectionally averaged void fraction time series in the EIT for different gas and liquid velocities. These results provide the inlet slug length and dissipation length in the EIT branches. The CFD results are evaluated against the experimental data demonstrating that the slug dissipation occurring in EIT branches can be predicted by simulation.

scholarly journals CFD Analysis of Turbulent Fibre Suspension Flow

Fluids ◽  
2020 ◽  
Vol 5 (4) ◽  
pp. 175
Author(s):  
Vijay Shankar ◽  
Anton Lundberg ◽  
Taraka Pamidi ◽  
Lars-Olof Landström ◽  
Örjan Johansson
Keyword(s):  
Experimental Data ◽  
Fibre Orientation ◽  
Fluid Model ◽  
Orientation Distribution ◽  
Suspension Flow ◽  
Viscoplastic Fluid ◽  
Fibre Suspension ◽  
Orientation Tensors ◽  
Good Potential ◽  
Rigorous Study

A new model for turbulent fibre suspension flow is proposed by introducing a model for the fibre orientation distribution function (ODF). The coupling between suspended fibres and the fluid momentum is then introduced through the second and fourth order fibre orientation tensors, respectively. From the modelled ODF, a method to construct explicit expressions for the components of the orientation tensors as functions of the flow field is derived. The implementation of the method provides a fibre model that includes the anisotropic detail of the stresses introduced due to presence of the fibres, while being significantly cheaper than solving the transport of the ODF and computing the orientation tensors from numerical integration in each iteration. The model was validated and trimmed using experimental data from flow over a backwards facing step. The model was then further validated with experimental data from a turbulent fibre suspension channel flow. Simulations were also carried out using a Bingham viscoplastic fluid model for comparison. The ODF model and the Bingham model performed reasonably well for the turbulent flow areas, and the latter model showed to be slightly better given the parameter settings tested in the present study. The ODF model may have good potential, but more rigorous study is needed to fully evaluate the model.

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