Permanent magnet dipole stirrer for aluminium furnaces

Abstract

Use of permanent magnet systems for metallurgical applications have been proposed before. We have continued development of such systems by investigation use of single magnetic dipole which is realized as permanent magnet cylinder. Magnet is magnetized orthogonal to its axis and has been mounted to the side of the liquid metal reservoir. System first was modelled using small scale experiment with galinstan melt. Velocity distributions and flow patterns in reservoir using Ultrasound Doppler Anemometer were acquired and will be presented here. Additionally, numerical model using Comsol and Cenos modelling software were developed alongside analytical, non-dimensional estimation calculations. Experimental results were used to adjust and verify calculations. Using these calculations, industrial scale system was modelled and designed, and built. Industrial prototype was installed to 20t aluminium remelting furnace in Norway. It demonstrated that sufficient flow for efficient stirring could be achieved, while power of unit did not exceed 2kW, what is up to 30 times less than for comparable size classical EM stirrers with current windings. Besides system allows unique versatility by changing tilt angle to change flow pattern continuously allowing adaptive melting process, and costs significantly less than classical systems. By the time of the conference another prototype will be commissioned and results will be included.