Tapping Process and Slag Retention Operation in Excentric Bottom Tapping (EBT) Electric Arc Furnaces

Tapping Process of Excentric Bottom Tapping Electric Arc Furnace

Once the molten steel within the electric arc furnace reaches the desired temperature and composition specifications, it is ready for tapping. The tapping procedure unfolds as follows:

1. Ladle Positioning

First, the ladle is transported to the designated position beneath the tapping box of the electric furnace, ensuring a smooth and efficient transfer of molten steel.

2. Furnace Tilt Initialization

Prior to opening the tapping port, the furnace is tilted towards the tapping side by an angle ranging from 3 to 5 degrees. This strategic tilt creates sufficient static pressure within the molten steel, effectively preventing slag from infiltrating the ladle through vortices generated during the tapping process.

3. Tapping Initiation and Control

Next, the tapping port support plate is opened, and tapping commences. Throughout this phase, the furnace is gradually tilted to an angle of approximately 12 degrees. This gradual tilt maintains a consistent depth of molten steel above the tapping port, ensuring a steady flow. When the molten steel level reaches around 95% of the ladle's capacity, the furnace body is rapidly tilted back to the horizontal position at a speed of 3 degrees per second. This swift action minimizes or eliminates slag flow into the ladle, achieving a slag-free tapping process.

Key Considerations During Tapping

• Tilt Speed Control: During the furnace tilt, it is crucial to avoid excessive speed to prevent the molten steel in the tapping box from coming into contact with the upper water-cooled cover plate, which could lead to burning losses.
• Molten Steel Height Maintenance: Ensuring an adequate height of molten steel in the tapping box is essential to prevent slag from being drawn into the ladle due to vortex effects.

Steel and Slag Retention Operation in Arc Melting Furnace

The EBT electric furnace is designed to retain a significant portion of steel and slag through its eccentric bottom tapping mechanism. Specifically, it can retain 10% to 15% of the steel and over 95% of the slag. This is achieved by leaving a residual amount of steel (10% to 15%) in the furnace, maintaining sufficient molten steel in the tapping box, and executing a rapid back tilt (3 degrees per second) of the furnace body during the tapping and tilting phases.

Advantages of Steel and Slag Retention

This innovative operation breaks away from traditional smelting processes and sets the stage for modern steelmaking practices. By retaining steel and slag, the arc remains stable throughout the smelting and melting periods. Additionally, the molten pool forms 10 to 15 minutes earlier, enabling advanced oxygen blowing and improved dephosphorization conditions for the molten steel.

Precautions for Steel and Slag Retention Operation

• Steel Grade Transition Considerations: When changing steel grades, it is important to assess whether the residual molten steel in the furnace will affect the new steel grade's composition.
• Lime Addition Timing: Lime should not be added before charging to avoid unwanted reactions or complications.
• Charging Basket Height Adjustment: The height of the charging basket should be appropriate during charging to prevent burning losses.
• Early Oxygen Blowing and Melting Aid: During smelting, it is advisable to initiate oxygen blowing and use melting aids in advance to optimize the process.
• Regular Cleaning and Inspection: The slag and molten steel should be cleaned regularly, and the erosion of the furnace bottom should be closely monitored to ensure optimal furnace performance and longevity.
•  We are a professional electric furnace manufacturer. For further inquiries, or if you require submerged arc furnaces, electric arc furnaces, ladle refining furnaces, or other melting equipment, please do not hesitate to contact us at  susie@aeaxa.com