The tundish process is the final process phase of the steel manufacturing process, during which the steel is in molten form before the continuous casting phase. In other words, the tundish process is critical for preventing the impurities of the steel before solidification.
Wear lining plays an important role in successful tundish processes. It is important to choose a tundish lining that is made from the right components, taking into account aspects such as critical impurities.
1. Make sure that the safety lining is in a good condition
The tundish safety lining can have notable holes and cracks during its lifecycle.
When the wear lining is installed using a form, the dry mix fills the holes and cracks in the safety lining, which can increase the dry mix consumption by up to 10%, resulting in higher tundish process costs.
The lining also becomes significantly thicker in these areas. A thicker lining is more likely to collapse at later process phases, because the material might not have time to cure completely during a standard curing program.
We recommend replacing the safety lining in due time to prevent major holes and cracks. The safety lining can also be patched up by casting or throwelling, but this is not a long-term solution because often, the cast or throwelled elements fall off during skull removal.
2. Careful skull removal
Before installing a new lining, the old wear lining is removed during the deskulling phase.
Typically, the tundish is turned upside down and the old lining is drained out. It is important to check that no hard clotted dry mass residue, steel or slag remain on the safety lining.
These material residues would likely, if not inevitably, cause the tundish lining to collapse. However, dry mass residue of the wear lining can be left on the back lining surface if the material has not been sintered but is still somewhat soft. In this case, the material can easily be used in the next lining process, which will also reduce the amount of new wear lining material needed. However, this is only possible, if there is enough space inside the tundish for the installation equipment despite the material residue. For example, if there are material residues on the bottom of the tundish, the automatic dry mix nozzle that is used for lining the bottom might not be able to move properly.
3. Form cleaning
The tundish installation method for dry mix uses form for the installation. Before placing the form inside the tundish, remember to check that the form is clean and free from dry mix residue. Any residue will result in a thinner wear lining. Furthermore, if the mix residue attaches itself to the new installed mix, the lining of the wall might collapse during form lifting. If dry mix remains on the form, the form becomes more stained with dry mass residue at each installation and more difficult to clean over time.
4. Check the form alignment
It is important to check that the form is placed in the centre of the dish in the correct alignment. This ensures that the correct lining thickness is achieved on each wall.
If the form is not aligned in the centre, the lining can be significantly thinner on one wall.
5. Ensure the correct curing time
Curing times typically range between 20–80 minutes. The curing time is a critical factor in successful tundish lining. If the curing time is too short, the lining does not cure properly, and if the time is too long, the form is attached to the lining. In both cases, the lining is probably ruined.
The correct curing time depends on the thickness of the wear lining, the safety lining temperature, the material used for the wear lining, and the curing program. We recommend planning the curing times together with the material supplier to determine the optimal curing time!
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