Characteristics of Eccentric Bottom Tapping Electric Arc Furnace

Eccentric Bottom Tapping Electric Arc Furnace (EBT EAF for short) is a key technology in modern electric arc furnace steelmaking. It significantly improves production efficiency and molten steel quality by optimizing the tapping method. The following are its core points, let us understand together.

Features of Eccentric Bottom Electric Arc Furnace

1. Basic structure

• Eccentric design: The tapping port is located at a position off-center from the bottom of the EAF furnace (usually opposite to the electrode arrangement area) to avoid interference with the slag in the furnace.

• Tapping system: It includes the tapping port, sliding gate (or stopper rod) and tapping trough. The tapping port is usually filled with magnesium refractory materials.

2. Working principle of EBT Electric Arc Furnaces

• Melting stage: The electrode heats the scrap steel or molten iron until it melts, and the furnace body remains upright.

• Tapping stage: The furnace body of the electric furnace tilts to the tapping side (about 10°~15°), the molten steel flows out from the bottom, and the slag layer remains in the furnace due to its low density, realizing slag-free tapping.

3. Technical advantages of eccentric bottom tapping electric arc furnace

• Reduce slag discharge: slag separation degree > 95%, reduce alloy element oxidation and phosphorus resulfurization.

• Energy saving & high efficiency: shorten tapping time (3~5 minutes/furnace), reduce heat loss by about 20%.

• Improved safety: avoid the risk of splashing in traditional tilting tapping.

• Extended refractory life: the life of refractory materials in the tapping area can reach 200~300 furnaces.

4. Key points of process control

• Steel retention operation: EAF electric furnace needs to retain 10%~15% molten steel as the molten pool basis for the next furnace.

• Tapping temperature: usually controlled at 1630~1680℃ (adjusted according to steel grade).

• Automated control: The laser slag measurement system monitors the tapping end point in real time.

5. Application & development

• Applicable scenarios: particularly suitable for smelting high-quality steel grades such as ultra-low phosphorus steel (P<0.010%) and high-alloy steel.

• Large-scale trend: The capacity of modern EBT electric arc furnaces can reach 150~200 tons, and the productivity can be increased by 30% when linked with LF refining furnace.

• Innovation direction: Double eccentric tapping (DEBT) technology can further optimize slag layer control.

6. Maintenance points

• The tapping port of the EAF electric furnace needs to be repaired with magnesia sand every day, and the casing needs to be replaced every 50 furnaces.

• Furnace bottom refractory thickness monitoring (<300mm requires early warning).

The technology of eccentric bottom tapping electric arc furnace reduces the power consumption of electric furnace steelmaking to 350~400kWh per ton of steel, significantly improving the compatibility with continuous steelmaking process, and becoming one of the core equipment of short-process steelmaking. In actual application, it is necessary to choose whether to cooperate with foam slag operation according to the type of steel to further save energy.