Dörrenberg Edelstahl GmbH (Engelskirche, Germany):

Stahl F., Prof.
Kühnemund M., Mag. Eng.

Max Eicher GmbH & Co. KG (Freilassung, Germany) [previously Helmut Schmidt University Hamburg (Hamburg, Germany)]:
Krüger K., Dr. Eng., Prof.

Siemens Corporate Technology (Erlangen, Germany):
Heigt M., Mag. Eng.
Hartmann W., Dr. Nat.

Primetals Technologies Germany GmbH (Erlangen, Germany):
Dittmer B., Mag. Eng.
Döbbeler A., Mag. Eng.
Matschullat Th., Dr. Eng., e-mail: thomas.matschullat@primetals.com

Many technical plasma applications use tailor-made plasma compositions, but not so electric arc steelmaking. The aim of our research project is to adapt the plasma conditions to the process requirements of the electric arc furnace process. This objective has completely been achieved. During scrap melting it is advisable to increase arc length for achieving energy-efficient large-scale scrap-melting. In contrast to that, arcs should be short during flat bath operation to avoid radiation losses. Based on sophisticated theoretical plasma simulations, appropriate gases for plasma modification were selected. Aim of the research project is to adapt the plasma conditions to the process requirements of the electric arc furnace process. This objective has absolutely been achieved. By inject ing argon through hollow graphite electrodes, an arc lengthening of up to 30% was obtained. The resulting long arcs allow for energy-efficient, large-volume scrap melting. Furthermore, current fluctuations and total harmonic distortion of the currents are significantly reduced by argon injection. This is another beneficial effect, especially during scrap melting. Not only arc lengthening was achieved, but also shortening. By injecting methane, an arc shortening of about 10 % was obtained. Higher gas flow rates promise an even stronger effect. Short, high-power arcs will come ahead with low radiation losses. As a further result successful simulation of the plasma behaviour has to be mentioned.

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