Device for maintaining a tap hole of an electric arc furnace

A tap hole maintenance device for cleaning an electric arc furnace comprising a furnace vessel that includes a furnace lower vessel having an eccentric or offset bottom tap hole extending along a first longitudinal axis (L1) and having a minimum diameter, and a furnace tilting device comprising a cradle, on which the furnace vessel is supported, configured to tilt the furnace vessel relative to a horizontal direction of a foundation that supports the electric arc furnace, the tap hole maintenance device comprising:

• a pivot arm configured to be pivoted between a parking position and a maintenance position,
• a lance attached at an end portion of the pivot arm and extending along a second longitudinal axis (L2), and
• a force detector configured to detect a force exerted by the lance head during movement from the lower end position to the upper end position,
• wherein:
• the lance comprises a lance head that is movable along the second longitudinal axis (L2) between a lower end position and an upper end position,
• the lance head has an outer diameter which is smaller than the minimum diameter of the bottom tap hole,
• the lance head comprises one or more lateral oxygen outlet nozzles extending at an outlet angle that is oblique downwards with respect to the second longitudinal axis (L2),
• the lance is configured to be attached to the furnace vessel and/or to the cradle such that the lance is movable together with the furnace vessel in response to tilting the furnace vessel and the lance is located under the bottom tap hole with the second longitudinal axis (L2) of the lance being coaxial with the first longitudinal axis (L1) of the tap hole in the maintenance position of the pivot arm, so that the lance head is movable into and through the tap hole in response to movement of the lance head from the lower end position to the upper end position,
• at least the lance head is configured to be moved in an automated manner between the upper end position and the lower end position, and
• the tap hole maintenance device is configured to stop automated movement of the lance head from the lower end position to the upper end position in response to detection of a force exerted by the lance head that meets or exceeds an upper limit value.