Direct Answer
Ca28Si60 reduces nozzle clogging in continuous casting by enabling controlled calcium treatment, transforming solid Al₂O₃ inclusions into liquid calcium aluminates, and stabilizing molten steel flow.
Background: Severe Nozzle Clogging in Continuous Casting
A steel plant producing carbon steel and low-alloy steel experienced persistent nozzle clogging issues in continuous casting.
Typical problems included:
- clogging in submerged entry nozzle (SEN) after 2–3 heats
- unstable casting speed and flow fluctuation
- frequent manual intervention and casting interruption
- increased defect rate in billets
The plant was using Ca31Si60 calcium silicon alloy,but clogging problems remained unresolved.
Root Cause Analysis of Nozzle Clogging
Detailed analysis of LF refining and casting process revealed:
- high residual aluminum in Al-killed steel (0.025–0.045%)
- total oxygen level before calcium treatment above 40 ppm
- excessively intense calcium reaction leading to unstable inclusion modification
- uneven calcium cored wire feeding & uneven alloy distribution in molten steel
This resulted in:
- formation of solid Al₂O₃ inclusions
- incomplete transformation into liquid calcium aluminates
- rapid buildup of deposits inside SEN
That's why severe nozzle clogging occurred despite using high-calcium alloy.
Solution: Switching to Ca28Si60 for Stable Calcium Treatment
To solve the clogging issue, the plant replaced Ca31Si60 with Ca28Si60 calcium silicon alloy, focusing on:
- reducing calcium reaction intensity
- improving inclusion modification stability
- achieving uniform calcium distribution
Process adjustments included:
- controlling total oxygen below 30 ppm before calcium addition
- optimizing calcium addition timing near casting stage
- reducing feeding rate to avoid local calcium oversaturation
- improving slag absorption conditions
Implementation in LF Refining Process
- Ca28Si60 (10–30 mm) added during late LF refining
- steel temperature controlled at 1580-1600°C
- Ca/Al ratio adjusted for stable inclusion modification
- batch consistency ensured for repeatable results
Results: Significant Reduction in Nozzle Clogging
1. Nozzle Clogging Performance
clogging delayed from 2–3 heats to 6–8 heats
reduced buildup of deposits inside SEN
longer continuous casting sequence
2. Inclusion Modification Improvement
reduction in solid Al₂O₃ inclusions
increased formation of liquid calcium aluminates
more uniform inclusion distribution
3. Casting Stability
smoother molten steel flow
stable casting speed
fewer interruptions
4. Production Efficiency
reduced downtime for nozzle cleaning
improved casting yield
lower operational cost
Why Ca28Si60 Works Better Than Ca31Si60
Controlled Calcium Activity
Ca28Si60 provides a more moderate calcium release, avoiding excessive reaction in molten steel.
Better Matching with Al-Killed Steel
More suitable for systems with high residual aluminum.
Improved Process Stability
Less sensitive to:
- temperature variation
- feeding timing
- addition rate
The key is not stronger reaction, but more controllable reaction.
Key Technical Insight
More calcium does not always reduce nozzle clogging.
In continuous casting:
excessive calcium leads to unstable inclusion phases
controlled calcium treatment leads to liquid inclusions and stable flow
Conclusion
By switching to Ca28Si60 and optimizing calcium treatment, the steel plant successfully reduced nozzle clogging, improved casting stability, and increased production efficiency.
For steelmakers facing clogging issues, Ca28Si60 offers a more stable and controllable solution.
Get Ca28Si60 for Nozzle Clogging Solutions
If you are dealing with:
- nozzle clogging in continuous casting
- unstable inclusion modification
- casting interruptions
We provide:
- stable Ca28Si60 supply
- consistent batch quality
- technical support for calcium treatment
👉 Request price, specifications, and application guidance for your steelmaking process.
