A ladle slide is a mechanical sliding control device for regulating the flow of molten steel. Its core principle is to use the relative displacement of multiple refractory sliding plates to regulate or cut off the flow of molten steel. The following is a detailed description of its working process:
1. Review of the basic structure
The ladle slide is mainly composed of the following key components:
Upper slide (fixed plate): fixed at the bottom of the ladle and in direct contact with the molten steel.
Lower slide (moving plate): slides horizontally under hydraulic or electric drive to control the flow.
Drive mechanism: hydraulic cylinder, electric actuator or manual lever to provide sliding power.
Sealing system: refractory fibre or spring compression device to prevent molten steel leakage.
2. Core working principle
(1) Flow rate adjustment (slide opening and closing)
Initial state (closed):
The upper and lower slide plates are completely misaligned, so that the molten steel cannot pass through and the flow is stopped.
The slide plates are spring-loaded or hydraulically pressed together to ensure a tight seal.
Opening process (regulating the flow):
The drive system (hydraulic/electric) pushes the lower slide plate horizontally, so that the upper and lower slide plates partially align.
The molten steel flows through the overlapping hole area. The greater the opening, the greater the flow.
Fully open:
The holes in the upper and lower slides are perfectly aligned, and the molten steel flows out at maximum flow rate.
(2) Shut-off (emergency shut-down)
When it is necessary to stop pouring (e.g. when changing ladles in continuous casting or in the event of a fault), the drive system quickly retracts the lower slide, misaligning the holes and instantly cutting off the flow of molten steel.
3. Key control parameters
Slide opening (mm): determines the flow rate and needs to match the continuous casting speed.
Slide speed: the response time of the hydraulic system is usually <1 second, ensuring rapid flow interruption.
Sealing pressure: A pressing force of 5–15 MPa between the slide plates is required to prevent penetration of the molten steel.
4. Comparison with the stopper rod system
Characteristics Slide plate system Stopper rod system
Control method Horizontal sliding adjustment of the holes Vertical lifting adjustment of the stopper head opening
Response speed Fast (hydraulic drive, <1 second) Slower (mechanical/manual adjustment)
Sealing properties Multi-layer slide plate compression, low risk of leakage Plug and seat brick are prone to wear and may leak steel
Applicable scenarios Continuous casting, high flow control Mold casting, small-scale pouring
5. Challenges and optimizations in practical applications
(1) Thermal deformation compensation
The slide plate will expand at high temperatures, so a thermal expansion gap (about 0.5-1mm) needs to be provided to prevent jamming.
Use low-expansion materials (such as ZrO₂-modified Al₂O₃) to reduce the impact of deformation.
(2) Anti-erosion design
The edges of the holes in the slide plate are coated with high-zirconium or composite coatings to reduce erosion and loss from molten steel.
Optimize the hole shape (such as a flared design) to reduce turbulent erosion.
(3) Automated control
Modern slide plate systems integrate PLC + sensors to monitor in real time:
Slide plate position (opening feedback)
molten steel flow (linked to the level of the tundish)
temperature (to prevent damage from overheating)
6. Typical workflow (using continuous casting as an example)
Ladle in position: The slide gate is initially closed.
Open the slide gate: The hydraulic system pushes the slide gate down to the appropriate opening, and the molten steel flows into the tundish.
Flow rate fine-tuning: The opening is dynamically adjusted according to the pulling speed to maintain a constant pouring speed.
Pouring finished: The slide is quickly reset to cut off the molten steel.
Replace the slide: After high-temperature wear, the refractory slide is replaced using a quick-release mechanism.
