EBT (Eccentric Bottom Tapping) is a modern electric furnace tapping technology, first jointly developed by Mannesmann-Demag and Thyssen in Germany in 1978. This technology sets a special tapping hole behind the bottom of the electric arc furnace, 20 to 60 cm close to the furnace wall. Through structural design and sealing system, the tapping process is more efficient and clean.
Structural features of EBT tapping hole
The EBT tapping hole is generally composed of two layers of refractory structure, namely “seat bricks” and “tapping bricks” (also known as steel bricks or sleeve bricks) installed inside it. The tapping bricks are firmly wrapped by the bottom ramming material and refractory materials, with top bricks installed on the upper part and tail bricks on the lower part. In addition, a filling hole is provided above the tapping hole for blocking during smelting.
When tapping, the tapping hole is opened by a slide device. The common slide plates are rotary or linear reciprocating, and the driving methods are pneumatic or hydraulic. When the slide plate is opened, the filling material is automatically discharged under the static pressure of the molten steel, and then the molten steel can flow out smoothly. If the molten steel fails to flow by itself, it can also be operated by blowing oxygen to assist the drainage.
Advantages of EBT technology in electric arc furnaces
The introduction of EBT technology in electric arc furnace steelmaking has brought significant operational and economic benefits, mainly in the following aspects:
- Expand the range of water-cooled furnace walls: It is convenient to optimize the furnace structure and thermal control.
- Achieve less slag or no slag steelmaking: Improve the cleanliness of molten steel and facilitate subsequent refining.
- Improve alloy recovery rate: Reduce alloy element loss and reduce production costs.
- Save time and shorten the smelting cycle: The steelmaking process is faster and the production rhythm is improved.
- Reduce the steelmaking temperature: Compared with the traditional tilting furnace steelmaking method, the energy consumption is lower.
- Reduce refractory material loss: Less scouring of the furnace lining and ladle, extending the service life.
- Reduce furnace tilting load: The EBT furnace tilting angle is generally controlled at -7° to -15°, and the mechanical stress is smaller.
- Optimize electrical system design: After the tilting angle is reduced, the busbar water-cooling cable can be shortened, heat loss is reduced, and the power factor is improved, which helps to save energy and reduce consumption.
