| Type | Description | Advantages | Disadvantages |
|---|---|---|---|
| Internal Stoppers | Plug, ball, or cone-shaped devices inserted into the tap hole | High accuracy in blocking slag; can be used in various furnace types | Limited lifespan due to high-temperature erosion; requires precise alignment |
| External Stoppers | Slide gates, flap stoppers, or siphon-shaped devices mounted outside the tap hole | Longer lifespan; easier maintenance; suitable for high-throughput operations | Higher initial investment; may require additional cooling systems |
| Pneumatic Stoppers | Gas pressure (e.g., nitrogen) is used to seal the tap hole | Non-contact operation; less affected by tap hole wear; rapid response | Gas consumption increases operating costs; requires reliable gas supply |
Insertion Mechanisms: Internal stoppers are typically inserted into the tap hole using a mechanical or hydraulic drive system. The stopper is precisely positioned to block the flow of slag while allowing molten steel to pass through channels or grooves in the stopper body.
External Slide Gates: Slide gates consist of a refractory slide plate that moves horizontally to open or close the tap hole. Hydraulic or pneumatic actuators control the movement, providing rapid and precise operation.
Pneumatic Sealing: Pneumatic stoppers use a stream of inert gas to create a barrier at the tap hole, preventing slag from entering the ladle. This method is particularly effective in reducing wear and tear on the stopper components.
Application: Two 300-ton LD converters were equipped with Siemens VAI Con Stopper systems to minimize slag carry-over.
Technology: Pneumatic sealing with nitrogen gas, allowing non-contact operation and reducing the impact of tap hole wear.
Results: Slag content in liquid steel reduced to less than 4 kg/t, leading to improved steel quality and reduced rephosphorization and resulfurization risks.
Application: Hydraulic slide gate system installed at the tap hole of a converter.
Technology: Automatic slag detection system combined with a quick-change slide gate mechanism.
Results: 100% slag blocking success rate, increased alloy yield, and reduced refining costs by approximately ¥2.84 per ton of steel.
Quality Improvement: Reduced slag carry-over minimizes the introduction of impurities into the steel, resulting in cleaner steel with improved mechanical properties and reduced defect rates.
Cost Savings: Lower alloy consumption, reduced refining times, and extended ladle life contribute to significant cost savings over the long term.
Safety Enhancement: Automated slag stopper systems reduce the need for manual intervention near the tap hole, improving overall safety in the steelmaking process.
Integration with Advanced Sensors: The use of infrared cameras, laser sensors, and other advanced detection technologies will enhance the precision of slag detection and improve the responsiveness of slag stopper machines.
Automation and Remote Control: Increased automation and remote operation capabilities will further improve safety and process control, especially in harsh environments.
Energy-Efficient Designs: Development of energy-efficient slag stopper systems will help reduce operational costs and environmental impact.
