The ladle upper nozzle (also called the inner nozzle) is a key refractory component of the ladle slide gate system. It is installed directly inside the well block at the bottom of the ladle, comes into direct contact with molten steel, and directs the steel into the slide gate system. The upper nozzle is not easily replaced, so it requires high resistance to molten steel erosion and thermal shock.
The ladle upper nozzle (also called the inner nozzle) is a key refractory component of the ladle slide gate system. It is installed directly inside the well block at the bottom of the ladle, comes into direct contact with molten steel, and directs the steel into the slide gate system. The upper nozzle is not easily replaced, so it requires high resistance to molten steel erosion and thermal shock.
The upper nozzle is typically made from selected bauxite and corundum as the main raw materials, with large flake graphite and metal additives, using phenolic resin as the binder, and is pressed into a carbon-containing unburned shaped product by a high-tonnage press. By function, it can be divided into permeable and non-permeable types. The permeable upper nozzle reduces nozzle clogging by argon blowing and prevents precipitates in the molten steel (such as Al₂O₃) from adhering to the nozzle wall. In recent years, the variable-diameter upper nozzle design (larger inner diameter at the top and smaller at the bottom) can effectively improve the flow of ladle filler sand, increase the free-opening rate of molten steel, and reduce manual oxygen lancing during casting start.
Upper nozzle models are usually matched with the slide gate mechanism. The Interstop-type slide gate is divided by bore diameter into 30, 50, and 70 types; the Interstop-type is divided by nozzle diameter into Type I (<25mm, <20t ladle), Type II (25~50mm, 20~100t), Type III (40~70mm, 90~200t), and Type IV (60~120mm, 180~300t).
Typical product grades and technical parameters :
| Item | ST-SSK-1 | ST-SSK-2 | ST-SSK-3 |
| Al₂O₃ (%) ≥ | 60 | 75 | 80 |
| C (%) ≤ | 4 | 6 | 6 |
| Bulk density (g/cm³) ≥ | 2.6 | 2.9 | 2.95 |
| Cold compressive strength (MPa) ≥ | 40 | 40 | 45 |
| Apparent porosity (%) ≤ | 15 | 14 | 13 |
Other specification references: For alumina-zirconia-carbon upper nozzles, the body bulk density (110℃×24h) is ≥2.35g/cm³, and the bowl is ≥2.5g/cm³. Inner diameter tolerance ±0.5mm, outer diameter tolerance ±1.0mm, crack width ≤0.1mm, lamination not allowed. Nozzle inner diameter and shape can be customized according to slide gate system design.
The ladle upper nozzle is dedicated to ladle slide gate systems in the iron and steel smelting industry. It is installed in the well block at the bottom of the ladle and performs the flow-guiding and flow-controlling function for molten steel from the ladle to the tundish (or downstream casting system).
Specific application scenarios include:
Installation method: Mechanical assembly. The outer surface of the upper nozzle is coated with matching mortar and pressed into the well block bore, aligned, and heated together with the ladle during overall preheating. Nozzle bore enlargement should be monitored during casting.
