ElectroMagnetic Stirrer for Molten Aluminum

ABB Metallurgy Products, a Centre of Excellence in the ABB Group, is a unit of ABB Automation Technologies AB, Västerås, Sweden. As a multinational company with operations throughout the world, ABB provides customers in the metals industry with stirrers and brakes of different types for metallurgical processes. One of our product lines is the AL-EMS, an Electromagnetic Stirrer for Aluminium Furnaces.

AL-EMS has been specifically developed to improve the production economy and give a better work environment. Well over 200 AL-EMS systems are today in operation worldwide. Experience from the operation of these installations shows that AL-EMS reduces the furnace cycle times, thereby providing a potential for higher productivity, decreased dross formation and improved dissolution and homogenisation of alloys. A payback time of less than one year can be expected in many cases. Customers are today showing a growing interest in AL-EMS for their aluminium furnaces.

 

Benefits

Increased productivity

It has been shown in aluminium plant operation that the cycle time for a top-charged 100-tonne melting furnace can be substantially reduced with the use of AL-EMS compared to manual stirring with a mechanical rake. An improved productivity of 10-25 per cent can be expected with AL-EMS.

This is the result of a higher melting rate, improved alloying conditions, better temperature management and reduced burner downtime. All these benefits are quite simply attributable to the reduction or even elimination of manual stirring, skimming and knockdown of scrap.

(Video: another example of Electromagnetic Stirrer)

Lower energy consumption

Energy savings of up to 15 per cent have been achieved with AL-EMS thanks to reduced dross formation, improved alloying and temperature homogenisation.

AL-EMS reduces both the cycle time and the surface temperature. By applying electromagnetic stirring of the bath we can achieve a considerably lower surface temperature. A dross reduction of 15-25 per cent can be expected.

Improved alloying

AL-EMS will give faster dissolution and homogenisation of alloy elements. With electromagnetic stirring less time is needed for the dissolution of the alloy elements, and the AL-EMS always promotes rapid and thorough chemical compositions in the bath. The yield is therefore substantially higher than is typically the case with mechanical stirring.

Better temperature homogenisation

AL-EMS contributes to representative readings of the bath thermocouples all the time, thereby giving a more reproducible transfer temperature.

Improved work environment

AL-EMS will reduce or even eliminate the need for manual stirring and in this way the risk of damage to the furnace refractory lining and furnace doors with a rake. This manual and usually arduous manual work, performed in a difficult environment, can now easily be accomplished from a control room via EMS, which also lowers the labour costs.

To sum up, AL-EMS ensures efficient mixing of the entire melt without the need for mechanical stirring. With the knowledge that a very accurate analysis and temperature are always obtained at the time of transfer, rejects later on in the process will be minimised. The operation of an AL-EMS is characterised by low stirring costs, reliability and safety, optimum conditions for the reproducible production of high-quality aluminium and precise logistics.