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Article
Publication date: 4 January 2016

Particle capture of elliptic cross-section matrices for parallel stream high gradient magnetic separation

Xiayu Zheng, Yuhua Wang and Dongfang Lu

The purpose of this paper is to model the particle capture of elliptic magnetic matrices for parallel stream type high magnetic separation, which can be a guidance for the…

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Abstract

Purpose

The purpose of this paper is to model the particle capture of elliptic magnetic matrices for parallel stream type high magnetic separation, which can be a guidance for the development of novel elliptic cylinder matrices for high-gradient magnetic separation (HGMS).

Design/methodology/approach

The magnetic field distribution around the elliptic matrices is investigated quantitatively and the magnetic field and gradient were calculated. The motion equations of the magnetic particles around the matrices were derived and the particle capture cross-section of elliptic matrices was studied and was compared with that of the conventional circular matrices.

Findings

Elliptic matrices can present larger particle capture cross-section than the conventional circular matrices and can be a kind of promising matrices to be applied to HGMS.

Originality/value

There is little literature investigating the magnetic characteristics and the particle capture of the elliptic matrices in HGMS, the study is of great significance for the development of novel elliptic magnetic matrices in HGMS.

Details

COMPEL: The International Journal for Computation and Mathematics in Electrical and Electronic Engineering, vol. 35 no. 1
Type: Research Article
DOI: https://doi.org/10.1108/COMPEL-03-2015-0140
ISSN: 0332-1649

Keywords

  • Magnetic devices
  • Magnetism
  • Magnetic separation
  • Magnetic field and gradient
  • Elliptic cylinder matrices
  • Capture cross-section

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Article
Publication date: 1 January 2014

Magnetic separation of magnetic activated carbons for water treatment and reuse

Chiara Caterina Borghi, Yoko Akiyama, Massimo Fabbri, Shigehiro Nishijima and Pier Luigi Ribani

The aim of this paper is the study of the magnetic separation of pollutants from water by means of a magnetic filter. A magnetic activated carbons nanometric powder that…

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Abstract

Purpose

The aim of this paper is the study of the magnetic separation of pollutants from water by means of a magnetic filter. A magnetic activated carbons nanometric powder that combines the well-known pollutants absorbent capacity of activated carbons with the magnetic properties of magnetite (Fe3O4) is used.

Design/methodology/approach

The considered magnetic filter is made of stainless steel spheres, magnetized by an external flux density field provided by permanent magnets. Flux density and fluid velocity fields are evaluated using volume integral equation method. The modelling of the particles trajectories inside the filter allows calculating its capture efficiency.

Findings

The results of the model are tested on the experimental data obtained using two different setups. A removal of the powder larger than 90 percent is achieved in both cases. The pollutant removal efficiency is checked on surfactants (water diluted). Their adsorption on magnetic activated carbons leads to residual concentration below the limit for the reuse in agriculture (according to the Italian legislation) for all the tested surfactants.

Originality/value

The proposed process combines efficiently a physico-chemical phase of adsorption and a magnetic phase of filtration due to the particular properties of magnetic activated carbons.

Details

COMPEL: The International Journal for Computation and Mathematics in Electrical and Electronic Engineering, vol. 33 no. 1/2
Type: Research Article
DOI: https://doi.org/10.1108/COMPEL-03-2013-0088
ISSN: 0332-1649

Keywords

  • Filtration
  • Magnetic activated carbons
  • Magnetic separation
  • Magnetostatics
  • Water reuse
  • Water treatment

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Article
Publication date: 5 March 2018

A neural network for electromagnetic based ore sorting

Min Li, Arber Caushaj, Rodrigo Silva and David Lowther

This paper aims to presents a novel application of neural network (NN) pattern recognition to ore rock sorting using inductive electromagnetic (EM) sensors.

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Abstract

Purpose

This paper aims to presents a novel application of neural network (NN) pattern recognition to ore rock sorting using inductive electromagnetic (EM) sensors.

Design/methodology/approach

The impedance of a metallic rock can be measured with an inductive method based on Faraday’s law and eddy current theory. A virtual rock model is then created for the simulation of the EM measurements. An NN is trained to differentiate between waste and useful ore samples (containing high amount of minerals) based on the EM sensor signals produced by the rocks.

Findings

The NN solution showed high accuracy of rock classification and produced relatively robust results from signals with noise.

Originality/value

A pattern recognition NN was applied to classify low- and high-grade ore samples. It has the potential to determine the approximate amount of conductive materials inside ore rocks through multiple classes. This method can be used to improve the performance of EM-based ore sorting for mineral pre-concentration.

Details

COMPEL - The international journal for computation and mathematics in electrical and electronic engineering, vol. 37 no. 2
Type: Research Article
DOI: https://doi.org/10.1108/COMPEL-12-2016-0529
ISSN: 0332-1649

Keywords

  • Sensors
  • Neural networks
  • Eddy currents
  • Nondestructive testing
  • Pattern recognition
  • Electromagnetic sensor

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Article
Publication date: 28 October 2014

Magnetic field effect on Soret driving free convection in an inclined porous cavity saturated by a conducting binary mixture

Rtibi Ahmed, Hasnaoui Mohammed and Amahmid Abdelkhalk

The purpose of this paper is to study analytically and numerically the effect of a transverse magnetic field on the separation of species induced in an inclined…

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Abstract

Purpose

The purpose of this paper is to study analytically and numerically the effect of a transverse magnetic field on the separation of species induced in an inclined rectangular porous cavity saturated with an electrically conducting mixture.

Design/methodology/approach

The porous layer is assumed homogeneous and submitted from its long sides to uniform heat fluxes and to a magnetic field of strength B. The Darcy model combined with the Boussinesq approximation are used to study the heat and solute transfer in the medium. An analytical solution is developed on the basis of the parallel flow approximation. Numerical simulations are also performed in order to validate the analytical solution. The controlling parameters of this problem are the thermal Rayleigh number, the inclination of the enclosure, the separation parameter, the Hartmann number and the Lewis number.

Findings

For given values of the thermal Rayleigh number, the inclination of the enclosure, the separation parameter and the Lewis number, there is an optimal magnetic field which leads to a maximum of separation. At relatively high Rayleigh numbers, where convection destroys the separation process, it is possible, with an optimal choice of the Hartman number, to recover a good level of separation.

Research limitations/implications

Since the problem is governed by several parameters (five parameters), only the Darcy model was used in this study instead of the Darcy-Brinkman extended model even if the latter model allows to cover the pure fluid and Darcy porous media as limiting cases.

Practical implications

In separation experiments, it is very difficult technically to work with small Rayleigh numbers due to technical difficulties. However, the process of separations is canceled at high Rayleigh number by the strength of convection which causes a mixing in the binary mixture. This study shows that, by using adequate combinations of the controlling parameters, it becomes possible to reach a good level of separation even at relatively high Rayleigh numbers.

Originality/value

Optimum choice of the magnetic field and the inclination of the cavity may lead to a good level of the separation process. For large Lewis numbers, the separation vanishes far above and far below the optimal Ha. However, for small Lewis numbers, an important level of separation is maintained for any Ha located below the optimal value of the latter parameter.

Details

International Journal of Numerical Methods for Heat & Fluid Flow, vol. 24 no. 8
Type: Research Article
DOI: https://doi.org/10.1108/HFF-06-2013-0189
ISSN: 0961-5539

Keywords

  • Natural convection
  • Analitycal and numerical study
  • Inclined porous cavity
  • Magnetic field
  • Separation of species

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Article
Publication date: 1 June 2000

Electromagnetics and coupled problems

P.Di Barba

Introduces the fourth and final chapter of the ISEF 1999 Proceedings by stating electric and magnetic fields are influenced, in a reciprocal way, by thermal and mechanical…

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Abstract

Introduces the fourth and final chapter of the ISEF 1999 Proceedings by stating electric and magnetic fields are influenced, in a reciprocal way, by thermal and mechanical fields. Looks at the coupling of fields in a device or a system as a prescribed effect. Points out that there are 12 contributions included ‐ covering magnetic levitation or induction heating, superconducting devices and possible effects to the human body due to electric impressed fields.

Details

COMPEL - The international journal for computation and mathematics in electrical and electronic engineering, vol. 19 no. 2
Type: Research Article
DOI: https://doi.org/10.1108/03321640010733403
ISSN: 0332-1649

Keywords

  • Simulation
  • Electronics
  • Numerical control
  • Modelling
  • Health

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Article
Publication date: 1 July 2014

Iso-geometric shape optimization of magnetic density separators

Nguyen Dang Manh, Anton Evgrafov, Jens Gravesen and Domenico Lahaye

The waste recycling industry increasingly relies on magnetic density separators. These devices generate an upward magnetic force in ferro-fluids allowing to separate the…

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Abstract

Purpose

The waste recycling industry increasingly relies on magnetic density separators. These devices generate an upward magnetic force in ferro-fluids allowing to separate the immersed particles according to their mass density. Recently, a new separator design has been proposed that significantly reduces the required amount of permanent magnet material. The purpose of this paper is to alleviate the undesired end-effects in this design by altering the shape of the ferromagnetic covers of the individual poles.

Design/methodology/approach

The paper represents the shape of the ferromagnetic pole covers with B-splines and defines a cost functional that measures the non-uniformity of the magnetic field in an area above the poles. The authors apply an iso-geometric shape optimization procedure, which allows us to accurately represent, analyze and optimize the geometry using only a few design variables. The design problem is regularized by imposing constraints that enforce the convexity of the pole cover shapes and is solved by a non-linear optimization procedure. The paper validates the implementation of the algorithm using a simplified variant of the design problem with a known analytical solution. The algorithm is subsequently applied to the problem posed.

Findings

The shape optimization attains its target and yields pole cover shapes that give rise to a magnetic field that is uniform over a larger domain.

Research limitations/implications

This increased magnetic field uniformity is obtained at the cost of a pole cover shape that differs per pole. This limitation has negligible impact on the manufacturing of the separator. The new pole cover shapes therefore lead to improved performance of the density separation.

Practical implications

Due to the larger uniformity the generated field, these shapes should enable larger amounts of waste to be processed than the previous design.

Originality/value

This paper treats the shapes optimization of magnetic density separators systematically and presents new shapes for the ferromagnetic poles covers.

Details

COMPEL: The International Journal for Computation and Mathematics in Electrical and Electronic Engineering, vol. 33 no. 4
Type: Research Article
DOI: https://doi.org/10.1108/COMPEL-07-2013-0234
ISSN: 0332-1649

Keywords

  • Magnetic fields
  • Numerical methods
  • Shape optimization
  • Computational geometry
  • Discretization

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Article
Publication date: 1 March 2003

Removal of SiC inclusions in molten aluminium using a 12 T static magnetic field

Fabrizio Colli, Massimo Fabbri, Francesco Negrini, Shigeo Asai and Kensuke Sassa

The analysis of particles trajectories in a vertical cylindrical coil shows that the magnetization force acting on paramagnetic particles has predominantly axial component…

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Abstract

The analysis of particles trajectories in a vertical cylindrical coil shows that the magnetization force acting on paramagnetic particles has predominantly axial component which aims upwards and opposite to the gravitational force. In case of superconducting coil and depending on the value of the particle susceptibility, the axial force component can exceed several times the force of gravity. As a result, a motion of the particles in vertical upward direction appears. This effect was utilized to realize a magnetic separator, the main advantage of which is the high effectivity of separation process. A NbTi SC coil generates the magnetization force with a flux density field up to 12 T. Experiments with SiC inclusions in molten Aluminium have been performed to confirm the feasibility of this segregation concept.

Details

COMPEL - The international journal for computation and mathematics in electrical and electronic engineering, vol. 22 no. 1
Type: Research Article
DOI: https://doi.org/10.1108/03321640310452169
ISSN: 0332-1649

Keywords

  • Electromagnetics
  • Aluminium
  • Conductivity

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Article
Publication date: 8 July 2020

Fe3O4@SiO2 magnetic nanocomposites as adsorbents for removal of diazinon from aqueous solution: isotherm and kinetic study

Zahra Shamsizadeh, Mohammad Hassan Ehrampoush, Zahra Dehghani Firouzabadi, Tahereh Jasemi Zad, Fereshteh Molavi, Ali Asghar Ebrahimi and Mohammad Kamranifar

The purpose of this study was to the synthesis of Fe3O4@SiO2 nanocomposites and using it as an adsorbent for removal of diazinon from aqueous solutions. Structural…

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Abstract

Purpose

The purpose of this study was to the synthesis of Fe3O4@SiO2 nanocomposites and using it as an adsorbent for removal of diazinon from aqueous solutions. Structural characteristics of the synthesized magnetic nanocomposite were described by Fourier transform infrared spectroscopy and scanning electron microscopy.

Design/methodology/approach

The effects of different parameters including pH (2-10), contact time (1-180 min), adsorbent dosage (100-2000 mg L−1) and initial diazinon concentration (0.5–20 mg L−1) on the removal processes were studied. Finally, isotherm and kinetic and of adsorption process of diazinon onto Fe3O4@SiO2 nanocomposites were investigated.

Findings

The maximum removal efficiency of diazinon (96%) was found at 180 min with 1000 mg L−1 adsorbent dosage using 0.5 mg L−1 diazinon concentration at pH = 7. The experimental results revealed that data were best fit with the pseudo-second-order kinetic model (R2 = 0.971) and the adsorption capacity was 10.90 mg g−1. The adsorption isotherm was accordant to Langmuir isotherm.

Originality/value

In the present study, the magnetic nanocomposites were synthesized and used as an absorbent for the removal of diazinon. The developed method had advantages such as the good ability of Fe3O4@SiO2 nanocomposites to remove diazinon from aqueous solution and the magnetic separation of this absorbent that make it recoverable nanocomposite. The other advantages of these nanocomposites are rapidity, simplicity and relatively low cost.

Details

Pigment & Resin Technology, vol. 49 no. 6
Type: Research Article
DOI: https://doi.org/10.1108/PRT-02-2020-0010
ISSN: 0369-9420

Keywords

  • Adsorption
  • Magnetic nanocomposite
  • Aqueous solution
  • Diazinon
  • Isotherm
  • Kinetic

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Article
Publication date: 3 January 2017

Heat and mass transfer analysis in natural convection flow of nanofluid over a vertical cone with chemical reaction

P. Sudarsana Reddy and A. Chamkha

In recent years, nanofluids are being widely used in many thermal systems because of their higher thermal conductivity and heat transfer rate. The higher thermal…

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Abstract

Purpose

In recent years, nanofluids are being widely used in many thermal systems because of their higher thermal conductivity and heat transfer rate. The higher thermal conductivity depends on many parameters such as size, shape and volume and the Brownian motion and thermophoresis of added nanoparticles. The purpose of this paper is to analyze the influence of the Brownian motion and thermophoresis on natural convection heat and mass transfer boundary layer flow of nanofluids over a vertical cone with radiation.

Design/methodology/approach

Using similarity variables, the non-linear partial differential equations, which represent momentum, energy and diffusion, are transformed into ordinary differential equations. The transformed conservation equations are solved numerically subject to the boundary conditions by using versatile, extensively validated, variational finite-element method.

Findings

The sway of significant parameters such as magnetic field (M), buoyancy ratio parameter (Nr), Brownian motion parameter (Nb), thermophoresis parameter (Nt), thermal radiation (R), Lewis number (Le) and chemical reaction parameter (Cr) on velocity, temperature and concentration evaluation in the boundary layer region is examined in detail. The results are compared with previously published work and are found to be in agreement. The velocity distributions are reduced, while temperature and concentration profiles elevate with a higher (M). With the improving values of (R), the velocity and temperature sketches improve, while concentration distributions are lowered in the boundary layer region. The temperature and concentration profiles are elevated in the boundary layer region for higher values of (Nt). With the increasing values of (Nb), temperature profiles are enhanced, whereas concentration profiles get depreciated in the flow region.

Social implications

In recent years, it has been found that magneto-nanofluids are significant in many areas of science and technology. It has applications in optical modulators, magnetooptical wavelength filters, tunable optical fiber filters and optical switches. Magnetic nanoparticles are especially useful in biomedicine, sink float separation, cancer therapy, etc. Specific biomedical applications involving nanofluids include hyperthermia, magnetic cell separation, drug delivery and contrast enhancement in magnetic resonance imaging.

Originality/value

To the best of the authors’ knowledge, no studies have assessed the impact of the two slip effects, namely, Brownian motion and thermophoresis, on the natural convection of electrically conducted heat and mass transfer to the nanofluid boundary layer flow over a vertical cone in the presence of radiation and chemical reaction; therefore, this problem has been addressed in this study. Comparison of the results of this study’s with those of previously published work was found to be in good agreement.

Details

International Journal of Numerical Methods for Heat & Fluid Flow, vol. 27 no. 1
Type: Research Article
DOI: https://doi.org/10.1108/HFF-10-2015-0412
ISSN: 0961-5539

Keywords

  • Nanofluid
  • Thermophoresis
  • Brownian motion
  • Radiation
  • Chemical reaction
  • Vertical cone

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Article
Publication date: 11 January 2016

Magnetic nanocomposite of activated charcoal for removal of Congo red dye: Equilibrium and kinetic modeling

Baskar Gurunathan, Dhanusree Viswanathan, Shravanthi Rajasekar and Garrick Bikku George

The purpose of this paper is to focus on the removal of Congo red dye from aqueous solution using magnetically separable novel adsorbent prepared by coating activated…

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Abstract

Purpose

The purpose of this paper is to focus on the removal of Congo red dye from aqueous solution using magnetically separable novel adsorbent prepared by coating activated charcoal on magnetic nanoparticles.

Design/methodology/approach

The synthesized magnetic nanocomposite of activated charcoal was characterized using Fourier transform infra-red (FTIR), scanning electron microscope (SEM) and energy dispersive spectroscopy (EDS) analysis. The removal of Congo red from aqueous solution using magnetic nanocomposite of activated charcoal was optimized. The equilibrium and kinetics modeling of adsorption of Congo red was analyzed.

Findings

The presence of activated charcoal on magnetic nanocomposite was confirmed by FTIR analysis. The average size of the nanocomposite was found to be 12.77 nm using SEM characterization. The elemental composition by EDS analysis confirmed the increase in concentration of carbon due the adsorption of Congo red dye. The optimum conditions for batch adsorption was found to be 1 g/L of adsorbent, dye concentration 50 mg/L, pH 3 and temperature 70°C. The adsorption of Congo red dye on magnetic nanocomposite of activated charcoal was found to follow Temkin adsorption isotherm.

Originality/value

The experimental data were found to fit well with the pseudo second-order kinetics and the rate of adsorption was found to be controlled by intra-particle diffusion.

Details

Management of Environmental Quality: An International Journal, vol. 27 no. 1
Type: Research Article
DOI: https://doi.org/10.1108/MEQ-05-2015-0087
ISSN: 1477-7835

Keywords

  • Adsorption
  • Adsorption isotherm
  • Characterization
  • Kinetic modelling
  • Magnetic nanocomposite

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