The Magnetic Field Simulation And Optimization Of Industrial Equipment For Electromagnetic Purification Of Molten Aluminum

Aluminum alloys have wide applications in aerospace, transportation, electronics, construction and other fields. Recently, with the development of a series of high-strength and high-toughness aerospace aluminum alloys and a variety of high-performance civilian aluminum alloys,there has been demanding requirements on the technology of molten aluminum purification to completely remove inclusions larger than 10 μm and minimize the number of micro-sized inclusions of 1-10μm in diameter. Electromagnetic purification technology has received much attention world widely since 1980 s. By the action of an electromagnetic field, it can promote the rapid separation of fine inclusions from molten metals inside a ceramic tube separator to the wall surface. Based on a large number of laboratory investigations and pilot experiments, this technology has been applied in the twin roll casting of aluminum sheet and continuous casting and rolling of aluminum rod for electrical use. Structural design and optimization of the magnetic field of the electromagnetic generator is the core of the electromagnetic purification device for industrial use, but it was lack of in-depth research.This paper presented two kinds of electromagnetic purification equipment for industrial use. Base on sampling and quantitative metallography, the removal efficiency of inclusions of different sizes was statistically analyzed. Simulation of the magnetic field generated by the two types of electromagnetic purification device was conducted using the commercial finite element software Ansoft. The influence of relevant parameters on the strength and distribution of the magnetic field was also studied.The quantitative metallographic analysis showed that both the electromagnetic purification device with C-type cored coils and with dual parallel coils of 7 turns can not only effectively remove the inclusions of 10-30μm unfiltered by common ceramic foam filters, but also decrease the content of the inclusions smaller than 10μm by 36%-61%.Simulation of the magnetic field of the electromagnetic purification equipment with C-type cored coils show that it can generate a magnetic field of 0.01-0.03 T in the air gap that can basically meet the requirements of the electromagnetic separator. The magnetic flux density is higher in ends along the longitudinal direction and is more uniform in the cross-section. It can effectively change the magnetic field intensity distribution in the air gap by changing the air gap length, while changing the cross-sectional size of the core and the position of the center coil has little influence.A magnetic flux density of 0.015-0.04 T can be achieved inside the dual 7-turn parallel coils. The magnetic flux density is smaller in ends along the longitudinal direction and increases when approaching the inner surface of coils along radial direction. The use of yoke can significantly reduce external flux leakage of the coils, but hardly change the distribution of the internal magnetic field of the coil. Compared with the magnetic field generated by the purification device with C-type cored coils, the magnetic field inside the dual 7-turn parallel coils has advantage in both higher flux density and better uniformity.