Behavior of Conducting Liquid within an Arc Furnace in a Vertical Magnetic Field

Resumo

In a vertical magnetic field, bulk electromagnetic forces arise in conducting melt within the bath of a dc arc furnace. As a result, the melt is set in motion. The flow of slag and metal in the furnace bath may lead to effective mixing but may also have negative consequences, such as increased lining wear in the region of the hearth electrode. There has been little research on conductive mixing in the bath of a dc arc furnace. Theoretical concerns include the character of the flow in the bath under the action of magnetic fields of specific magnitude; practical considerations include the lack of simple and reliable sources of magnetic fields. In the present work, the utility of a transparent physical model in studying the flow of conducting liquid in an external vertical magnetic field is investigated. The applicability of the modeling results to processes in the 5-t bath of an industrial dc arc furnace is analyzed. It proves possible in principle to study the flow of conducting melt in external vertical magnetic fields on models based on transparent nonmetallic conducting liquids. The use of an aqueous solution of table salt permits assessment of the liquid velocity at its free surface and close to the hearth electrode by video recording. By physical modeling of the flow of conducting fluid in the bath under the action of an external vertical magnetic field, with different switching sequences of the hearth electrode and different currents in the bath, it is possible to establish the character of the liquid flow when the hearth electrode is at the center of the bath or somewhat displaced. The mean rate of liquid rotation in the horizontal plane is increased when the hearth electrode is at some distance from the bath axis. The strength of the vertical magnetic field producing conductive motion in the metal bath of a 5-t dc arc furnace is estimated: around 5 kA/m.