a brief introduction of nozzle brick

A nozzle brick is a refractory steel outlet embedded in the base bricks at the bottom of the ladle. Made of materials such as clay, high-alumina, and magnesium, it ranges in diameter from 20 to 120 mm. Its upper opening features a curved surface to reduce resistance, while its lower section is straight to stabilize flow. It achieves a seal through linear contact with the stopper brick. The diameter is selected to adjust the pouring speed based on the ladle capacity, pouring method, and steel grade. During installation, it must fit snugly against the base bricks to prevent leakage.

Sliding nozzle bricks adjust flow by sliding up and down. Their production involves oil immersion and calcination, and they utilize a phenolic resin binder and a specific particle size distribution for enhanced durability. A nozzle brick is a refractory steel outlet embedded in the base bricks at the bottom of the ladle. When not pouring, the nozzle brick and stopper brick maintain linear contact to prevent leakage. The upper opening of the nozzle brick features a curved surface to facilitate opening and closing the nozzle and reduce resistance to molten steel flow, while the lower section is straight to stabilize flow. For a given ladle capacity, the inner diameter of the nozzle brick directly affects the pouring speed.

Depending on the ladle capacity, pouring method, and steel grade, the nozzle diameter can range from 20 to 120 mm. The nozzle brick can be installed from the inside (as shown in Figure 1a) or the outside (as shown in Figure 1b), and its shape is shown in Figure 1. Nozzle bricks can be made of clay, high-alumina, magnesia, magnesia-chromium, and zirconium. When pouring rimmed steel and high-manganese steel, clay nozzles are susceptible to erosion, so magnesia or high-alumina nozzle bricks are used. Magnesia nozzles are highly erosion-resistant but also have high thermal conductivity, making them prone to nodules during pouring.

Upper nozzle

It is directly embedded in the base brick and requires a material that is resistant to high temperatures, corrosion, and erosion. Therefore, it has a longer service life than sliding bricks. Upper nozzles are available in either permeable or non-permeable configurations. Permeable upper nozzles are commonly used in tundish sliding nozzles to reduce nozzle blockage and improve molten steel quality. The vent holes are typically multi-porous, which produces uniform bubbles while minimizing gas volume and facilitates their upward movement within the mold. Materials commonly used include alumina, corundum, or mullite. To improve the performance of the upper nozzle material, a small amount of chlorine and chlorine are sometimes added to enhance the erosion resistance of the nozzle bricks. The main causes of upper nozzle damage include: chemical attack and erosion from molten steel and slag; mechanical damage during installation; and damage from oxygen burning and cleaning.

The main factors that damage the nozzle include: chemical erosion and scouring by molten steel and slag; mechanical damage during installation; and damage caused by oxygen burning and cleaning of the nozzle. Figure 2 shows the physical and chemical indicators of a ventilated nozzle from Shinagawa, Japan.

The drain nozzle

The drain nozzle is primarily used to control the flow rate and velocity of molten steel. It requires excellent erosion resistance and high-temperature volume stability. Materials typically used are high-aluminum, aluminum-carbon, and aluminum-zirconium-carbon. The main causes of damage are: erosion and erosion by molten steel and slag, cracking or breakage caused by temperature fluctuations, and melt loss caused by oxygen-fired pouring. To improve the drain nozzle's thermal shock resistance, it is installed in an iron sleeve to prevent cracking. Avoid oxygen-fired pouring during use. Figure 3 shows the physical and chemical characteristics of domestically produced drain nozzle bricks.