Proper charging method directly affects carbon absorption rate. Here are the main methods, from most to least effective.
Recommended Method: Bottom Charging
Best absorption rate: 90% – 95%
How to do it:
Put a small amount of scrap iron on the furnace bottom.
Mix recarburizer with steel scrap and place in the middle-lower part of the charge.
Cover with remaining scrap to press it down.
Key tips:
Add in batches with each layer of scrap, not all at once.
Don't skim slag too early - you may remove undissolved recarburizer.
Advanced Technique: "Heel" Practice
For continuous melting operations
Leave some molten iron (20–40 kg) from the previous heat in the furnace.
Add recarburizer onto this molten heel, then cover with scrap.
Advantage: Pre-heated iron reduces burn-off and improves absorption.
Late-Stage Adjustment
For fine-tuning only
Skim slag off the molten iron surface.
Add recarburizer on top.
Use stirring to help it dissolve.
Note: Lower absorption rate (80% – 95%). Only use for small corrections.
Not Recommended: Adding During Tapping
Putting recarburizer in the ladle or adding it while pouring from furnace to ladle.
Why avoid: Absorption rate is only about 50% and very unstable.
Products Description
Quick Summary
| Method | Absorption Rate | When to Use |
|---|---|---|
| Bottom Charging | 90% – 95% | Best choice for most operations |
| "Heel" Practice | Very High | Continuous production |
| Late-Stage Addition | 80% – 95% | Minor carbon adjustments only |
| Tap-Stream Addition | ~50% | Avoid – poor results |
Bottom Line
For the best results, use Bottom Charging with batch layering and proper covering. This gives you the highest carbon recovery and most consistent casting quality.
