Steelmaking in electric arc furnaces (EAFs) involves melting the metal using high-voltage electric arcs. If molten steel is not stirred, it develops inconsistencies in temperature and chemical composition. Metal can solidify at the bottom of furnace forming what steelmakers call the “skull”. These effects degrade product quality and increase energy consumption.

Stirring solves these problems by ensuring that heat and alloying elements are distributed evenly throughout the melt, improving homogeneity and accelerating scrap dissolution. 

In some furnaces, stirring is mechanical or gas-based, but these methods have limitations in control, efficiency, and maintenance. Electromagnetic stirring (EMS) was invented in 1937 in Sweden by Dr. Ludwig Dreyfus of ABB’s predecessor company, ASEA. The method is suited for conductive molten materials such as steel, aluminum, and copper. The latest version of this stirrer, ArcSave, pushes the advantages to higher levels.

ABB’s electromagnetic stirrers are essentially huge electromagnets placed beneath the furnace. The physical principle is pretty much the same as for an electric motor. Fixed electromagnets create moving magnetic fields that in turn induce currents and electromagnetic forces inside the molten steel – and keeps the melt moving. This approach is non-invasive, powerful, and controllable.

Stirring ahead

An onboard battery can be used as the main energy source in battery electric vehicles and enable them to operate over non-electrified sections. In hybrid vehicles, the battery works as a buffer storage and provides peak power that helps to reduce the installed power of the primary power source, be it the diesel engine or a fuel cell, and allows the recuperation of braking energy. Further, peak shaving helps to operate the primary power source more often at its maximum efficiency point and reduce fuel consumption.