The electromagnetic filtration of molten aluminum using an induced-current separator

Abstract

The production of clean metal, free from oxides and other types of nonmetallic inclusions, is central to product quality and performance. Toward this end, electromagnetic filtration is an emerging technology for the purification of molten metals. This paper reviews the theory and the mechanism of the electromagnetic separation of incl usions from molten metal and describes the induced-current electromagnetic separator developed at the University of Alabama. The results of laboratory and large-scale experiments on the purification of molten aluminum demonstrate the capability of the system for producing superclean metals. Figure 1 . A schematic ofthe separation chamber of the induced-current separator.46

Electromagnetic Separation of Nonmetallic Inclusion from Liquid Metal by Imposition of High Frequency Magnetic Field

“…The methods of the imposition of the electromagnetic force are classified into the following six types: (a) simultaneous imposition of direct current and stationary magnetic field, [1][2][3] (b) imposition of alternating current, 4) (c) imposition of alternating magnetic field, [5][6][7][8] (d) imposition of traveling magnetic field, 9) (e) simultaneous imposition of alternating current and alternating magnetic field, 10,11) (f) imposition of stationary magnetic field. 12) In addition to these studies, Shu et al 13) and Makarov et al 14) recently investigated the availability of the electromagnetic separation theoretically.…”

Modelling the Electromagnetic Separation of Non-metallic Particles from Liquid Metal Flowing through a Two-stage Multichannel

“…Electromagnetic separation-a method of separating non-metallic inclusions from liquid metal by imposing an electromagnetic field to the channel or pipe (termed separator hereafter) through which the liquid metal flows-has been identified as a generic technology for the production of ultra-clean metals 3) because this process can be easily implemented by controlling the magnitude and direction of an imposed electromagnetic force. Laboratory-scale experiments have demonstrated successfully the separation of (i) non-metallic inclusions (Al 2 O 3 4) or SiC 5) ) from Al melt, (ii) Fe-rich phase from hypoeutectic Al-Si alloys, 3,6) primary Si particles from hypereutectic Al-Si alloys, 7) and Fe-Al-Zn dross from galvanizing Zn melt, 8,9) where a single straightpass circular or square separator with a uniform cross-section are commonly used.…”

“…Laboratory-scale experiments have demonstrated successfully the separation of (i) non-metallic inclusions (Al 2 O 3 4) or SiC 5) ) from Al melt, (ii) Fe-rich phase from hypoeutectic Al-Si alloys, 3,6) primary Si particles from hypereutectic Al-Si alloys, 7) and Fe-Al-Zn dross from galvanizing Zn melt, 8,9) where a single straightpass circular or square separator with a uniform cross-section are commonly used. For industrial applications, the feasibility of using a bundle of small channels for inclusion removal has also been investigated.…”

Effects of Secondary Flow on the Electromagnetic Separation of Inclusions from Aluminum Melt in a Square Channel by a Solenoid.

“…It can, in principle, remove even micrometer-sized inclusions at almost constant rate by using high-intensity force fields. 1,2) The main advantage of electromagnetic separation is that the electromagnetic expulsive force exerted on inclusion particles is only dependent on the difference in electrical conductivity between the inclusions and melt and independent of the density, chemical composition, or different phases (solid, liquid or gas) of the inclusions. 3,4) Another advantage is that it offers very clean processes in view of environmental protection, as the use of fluxes, generally chlorides or fluorides, is avoided.…”