Optimum Coil-System Layout for Magnet-Driven Superconducting Magnetic Density Separation

Optimum Coil-System Layout for Magnet-Driven Superconducting Magnetic Density Separation

Kosse, J.J. (University of Twente)
Dhallé, M. (University of Twente)
Tomás, G. (University of Twente)
Rem, P.C. (TU Delft Resources & Recycling)
ter Brake, H.J.M. (University of Twente)
ten Kate, H.H.J. (University of Twente)

2021

This article discusses the optimum layout of coils of a superconducting magnet system for magnetic density separation (MDS). MDS is a novel separation technology that combines a vertical magnetic field gradient with a ferrofluid to separate mixtures of non-magnetic particles based on their mass density. The MDS process can separate more than two types of particles in a single process step, thereby distinguishing it from other separation techniques using a ferrofluid. The authors are currently constructing a superconducting MDS demonstrator. Ideally, the gradient of the magnetic field magnitude should change only with the distance above the magnet but remain constant in a horizontal plane. In principle, such an ideal field profile can be generated with an infinite harmonic sheet current. In practice, edge effects appear due to the necessity of using a finite number of coils. These cause a horizontal component in the field gradient and also change the vertical component. We compare the vertical magnetic field gradient of various coil layouts to see which configuration performs best. To facilitate ease of production, the analysis is restricted to flat racetrack coils. The main result is that the specific shape of a racetrack coil has a larger influence on the vertical gradient than the number of coils. The feed particles need to be pushed through the separation chamber from the insertion to the collection point. One option to realize this is to use an MDS setup in which the magnet is inclined with respect to the horizontal plane. This tilting results in a horizontal magnetic force component, which drives feed particles through the fluid bed. We show that a three-coil layout provides the largest usable fluid bed depth for a wide range of tilt angles.

Edge effects
ferrofluid
magnet
magnetic density separation (MDS)
magnetic field gradient
racetrack coil
superconductor

http://resolver.tudelft.nl/uuid:8bdbf4a8-224b-4cc2-a81a-ba5593c608f2

https://doi.org/10.1109/TMAG.2021.3080178

0018-9464

IEEE Transactions on Magnetics, 57 (8)

Institutional Repository

journal article

© 2021 J.J. Kosse, M. Dhallé, G. Tomás, P.C. Rem, H.J.M. ter Brake, H.H.J. ten Kate