Operating Procedures for the Ladle Refining Furnace (LRF)

Operating Procedures for the Ladle Refining Furnace (LRF)

1. Introduction to the Ladle Refining Furnace

The Ladle Refining Furnace (LRF) is essential secondary metallurgy equipment. Its primary function is to refine molten steel tapped from primary smelting units—such as Electric Arc Furnaces (EAF), Basic Oxygen Furnaces (BOF), or Open Hearth Furnaces—and precisely adjust its temperature and composition. This process ensures the steel meets the stringent quality and temperature requirements for continuous casting and rolling, serving as a crucial process buffer. The LRF is a cornerstone of modern secondary (or ladle) refining technology.

2. Standard Operating Procedures (SOP)

The following procedures outline critical safety and operational steps for a typical twin-station ladle furnace system.

A. Pre-Operational Checks & Preparation:

1.  Safety Interlocks & Equipment: Verify that all interlocking protection devices, limit switches, and travel switches for the ladle transfer car are functional and safe.

2.  System Integrity Check: Inspect all mechanical components of key systems—including vacuum (if equipped), argon/nitrogen stirring, heating electrodes, wire feeding, and alloy addition systems—to confirm they are secure and operational before startup.

3.  Sampling Tools: Ensure sample spoons and molds are completely dry to prevent moisture-related explosions.

4.  Auxiliary Tools: Check that all necessary station tools and instruments are in good working order and readily available.

5.  Coordination: Notify the power supply unit and control room (e.g., vacuum control) as required to prepare for operation.

6.  Safety Signal: Activate the designated audible/visual alarm (bell, siren) before initiating any equipment movement.

B. Operational & Safety Protocols:

7.  Sequenced Start-up: Follow the prescribed procedure for applying high voltage to the electrodes and initiating vacuum degassing (where applicable).

8.  Ladle Car Movement: Before moving the ladle car, visually inspect the track and ensure the path is clear of obstructions.

9.  High Voltage Hazard: After power is applied to the electrodes, personnel are strictly forbidden from passing underneath high-voltage cables or components.

10. Pressure System Safety: When connecting or disconnecting pressure lines (e.g., for gas stirring), the system valve must be securely closed prior to the operation.

11. Oxygen Handling: Extreme caution must be exercised when using oxygen lances. Never place hands near the lance coupling point, and greasy gloves are strictly prohibited due to the fire/explosion risk.

12. Safe Sample Disposal: After taking a steel sample, pour any remaining molten steel into a designated, dry disposal area.

13. Vacuum Release: During vacuum break, all personnel must stand clear of the air inlet pipes and openings to avoid injury from rapid air inflow or potential splash.

C. Maintenance & Electrode Handling:

14. Safe Access for Maintenance: Prior to any inspection or work requiring personnel to access the roof or electrode mast area, the high-voltage circuit must be isolated. This involves removing the high-voltage key (or using a lock-out/tag-out procedure), ensuring power is disconnected. The operator must retain personal control of the safety key.

15. Electrode Changing Procedure: Electrode changes must be conducted under the command of an authorized supervisor. Use a proper steel wire rope sling to connect the lifting ring to the crane hook, ensuring the hook safety latch is engaged. Crucially, electrodes must be handled and replaced individually; simultaneous lifting of all three phases is strictly forbidden.

16. Housekeeping & General Safety: Do not store tools or materials on the furnace roof or operating bridges. When working at an elevated level, strictly prohibit dropping or throwing any objects to the floor below.

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