In modern electric arc furnace steelmaking, choosing the right hot metal charging method is essential for maximizing the physical and chemical heat of molten iron, reducing energy consumption, and improving productivity. Globally, three main methods are widely used:
1. Charging Molten Iron from the Furnace Roof
This method is mainly applied to electric arc furnaces with swing-open roof designs. After scrap steel is charged into the furnace, an overhead crane lifts the hot metal ladle and pours the molten iron directly from the furnace roof.
Example: The 70-ton DC electric arc furnace at Bayi Iron & Steel Co., Ltd. in Xinjiang adopts this method.
Advantages:
- Simple setup with no need for additional auxiliary equipment;
- Flexible control of charging timing and speed;
- Allows molten iron to be poured into the furnace door area to form a hot zone, enhancing oxygen lance efficiency for rapid decarburization;
- Shortens melting time, reduces electricity and iron consumption, and protects furnace lining.
Disadvantages:
- Poor scrap conditions may cause splashing, though this can be mitigated by adjusting scrap mix or charging after electrode penetration;
- Potential interference between scrap charging crane and hot metal charging crane (solved by using two cranes);
- Higher heat loss due to molten iron being poured from height.
2. Charging from the Furnace Door (Slag Door) via Dedicated Trough
This method uses a specialized hot metal trough car to pour molten iron from the slag door position into the furnace.
Drawbacks:
- Blockage by slag buildup or scrap piles often prevents the trough from entering;
- Poor trough car maintenance can delay hot charging;
- Dust emissions are difficult for the furnace roof dedusting system to capture, increasing pollution;
- Limits production efficiency, making it rarely used in practice.
3. Charging from a Dedicated Sidewall Port
This method is common in shaft-type electric furnaces and continuous charging Consteel furnaces, and is especially effective with supersonic oxygen lances or bundled oxygen lances.
Examples:
- Anyang Iron & Steel: A 100-ton shaft furnace with a dedicated sidewall hot metal port located at a 30° angle from the tap side. The molten iron is poured via a ladle or hot metal car into the port using hydraulic tilting;
- Guangdong Shaogang: A 90-ton Consteel furnace with a similar charging system.
Advantages:
- Stable and controllable process;
- Works well with high-efficiency oxygen blowing systems to accelerate refining reactions;
- Reduces heat loss compared to roof charging.
Conclusion
From a practical and operational perspective, roof charging and sidewall charging are the most successful and widely used hot metal charging methods in modern electric arc furnace steelmaking. Both effectively utilize the remaining heat of molten iron, shorten refining time, and reduce energy costs, making them valuable solutions for high-efficiency steel production.
