Tundish Nozzle For Steelmaking

In the steelmaking continuous casting process, the tundish nozzle system serves as the critical channel between the tundish and the mould. It is not a single component, but rather an integrated assembly consisting of metering nozzles, slide gate plates, and long nozzles (in certain configurations).

Its primary functions are to direct the molten steel flow path, precisely regulate the flow rate, and isolate the steel from external contamination. As such, it plays a vital role in ensuring casting stability and achieving qualified strand quality.

The tundish nozzle system must be fully synchronized with the rhythm of the continuous casting operation. Its usage is divided into four stages: pre-installation, casting flow control, online maintenance, and offline replacement, each requiring strict adherence to process specifications.

1. Pre-installation: Ensuring Sealing

Before casting begins, the nozzle system must be fully assembled and debugged. Key steps include:

Component matching: Select the appropriate nozzle material and bore size according to the steel grade and strand section.
For example, zirconia metering nozzles with higher erosion resistance are used for high-quality steel grades, while larger bore nozzles are selected for large cross-section strands.

Sealing assembly: Insert the metering nozzle into the nozzle seat brick at the bottom of the tundish and ensure sealing using refractory mud or mechanical clamping.
Install the stopper rod above the nozzle and adjust its coaxial alignment with the nozzle. The stopper rod is positioned directly above the nozzle and controlled by a lifting mechanism.

Preheating and drying: The nozzle system is heated together with the tundish (from room temperature to 1000–1200°C) to remove moisture and impurities, preventing thermal shock cracking when molten steel flows through.

2. Casting Flow Control: Dynamic Adjustment

Once molten steel is poured from the ladle into the tundish, the nozzle system enters its core operating phase:

Start of flow: The stopper rod is lifted to allow steel to flow through the metering nozzle into the mould. The rod must be raised slowly at first to avoid sudden flow surges and mould overflow.

Flow stabilization: The stopper rod is lowered to a fine-tuning position, where flow is primarily controlled by the fixed bore of the metering nozzle.
Based on orifice discharge principles, as long as the steel level remains stable, the flow depends only on bore size.
Mould level sensors continuously monitor the steel height; slight stopper rod adjustments are made if the level rises or falls, ensuring that the molten steel entering the mould equals the amount withdrawn as strand.

Special condition handling: If steel temperature drops or inclusions increase, the stopper rod may be slightly lifted or inert gas injected to prevent nozzle clogging.
In case of breakout risk, the stopper rod must be rapidly lowered to shut off flow.

3. Online Maintenance: Wear Monitoring

During casting, the nozzle gradually wears due to erosion and chemical attack. Maintenance measures include:

Real-time monitoring using flow sensors, thermal imaging, and manual inspection to assess wear conditions.

Auxiliary protection: In some systems, external protection sleeves or inert gas (e.g., nitrogen) are injected into the gap between the nozzle and mould to reduce air ingress and secondary oxidation, while slowing erosion of the nozzle exterior.

4. Offline Replacement

When nozzle wear exceeds the allowable range, it must be replaced after a heat is cast or when the tundish campaign ends.
Typical replacement conditions include bore enlargement >5%, visible cracking, or irreversible blockage.

After the tundish cools to room temperature:

1. Remove the worn nozzle.
2. Clean residual refractory material from the seat brick.
3. Install a new metering nozzle and stopper rod.
4. Repeat the pre-installation procedure to prepare for the next casting cycle.

Anyang Changtai Silicon Industry Co., Ltd. maintains a comprehensive product traceability system to ensure product performance meets the highest quality standards stipulated by ISO9001, ISO14001, and SGS guidelines, managed through our rigorous quality control system.
Our zirconia products feature high purity, exceptional high-temperature corrosion resistance, extended service life, and outstanding quality stability. Furthermore, we tailor designs to meet specific customer requirements for diverse operational environments and conditions. Our products are exported to markets worldwide. Click the button below to request a quote!

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