In the previous article, we discussed how to achieve high-performance machining of free-cutting steels through sulfide morphology control. Today, we focus on a critical step during BOF/EAF tapping that directly affects steel cleanliness and alloy yield: reducing slag carryover. Slag flowing into the ladle with the steel during tapping causes a series of problems: increased deoxidizer consumption, increased inclusions, refractory erosion, and phosphorus reversion. How can you effectively control slag carryover to protect steel quality at the source? Wuxi WeiDa Cored Wire Co.,Ltd provides a comprehensive solution based on slag stopping technology, carryover detection, and tapping process optimization.
The Harm of Slag Carryover
The harm caused by slag carryover is systematic. Every 1% increase in FeO in the slag can increase aluminum consumption by 0.5-1.0 kg per ton of steel. The carryover slag itself becomes large inclusions, while phosphorus reversion occurs (converter slag contains P₂O₅), and ladle refractories are eroded. Traditional slag stopping methods (slag stopping balls, slag stopping plugs, pneumatic slag stopping) each have limitations: low hit rate, difficult timing control, and complex equipment.
Our Solution
First, slag carryover detection system. Recommend electromagnetic or vibration-based slag carryover detection systems that alert operators within 0.5-1 second of slag carryover, providing time for slag stopping operations.
Second, composite slag stopping technology. Adopt a combination strategy of "slag stopping ball + pneumatic slag stopping." Use slag stopping balls to cover the tap hole area in the early stage. After the carryover alarm, activate pneumatic slag stopping to form an air curtain. At the end of tapping, use slag stopping plugs to block the tap hole.
Third, optimize tapping operation. Use a fast-first, slow-later tilting strategy, slowing down when 15-20% of the steel remains. Use bell-shaped tap holes to reduce vortex effects. Add covering flux or lime to the ladle before tapping to absorb some carryover.
Fourth, bottom argon stirring assistance. During tapping, turn on bottom argon for soft stirring to promote mixing and emulsification of carryover slag with the top slag, reducing its impact on deoxidizers.
Fifth, rapid post-tapping treatment. For severe carryover, perform mechanical slag raking, or add lime/aluminum particles to modify the slag, or feed synthetic slag cored wire to adjust the top slag composition.
Benefits
After implementation, customers typically achieve: slag carryover reduced by 50-70% , aluminum consumption reduced by 15-25% per ton of steel, large inclusions reduced by 30-50% , and ladle life extended by 15-20% .
From "Passive Acceptance" to "Active Blocking"
Through the four-pronged synergy of carryover detection, composite slag stopping, process optimization, and rapid treatment, you can transition from "passively accepting slag carryover" to "actively blocking slag carryover," laying a solid foundation for steel cleanliness at the tapping stage.
If you are troubled by high aluminum consumption, excessive inclusions, and rapid refractory erosion caused by tapping slag carryover, please visit https://www.weidamaterials.com/ to obtain the complete solution.