Composition of tundish lining and type of refractory material

The lining of the intermediate ladle primarily consists of the following components:

(1) Insulation layer

This layer is in direct contact with the steel shell of the intermediate ladle. The materials typically used include asbestos boards, insulation bricks, or lightweight refractory castables.

(2) Permanent layer

This layer is in contact with the insulation layer. The materials generally used include clay bricks.

(3) Working layer

This is the layer in direct contact with molten steel, i.e., the working layer. The lining materials for this layer primarily include: high-alumina bricks, alkaline bricks (such as magnesia bricks), silica-based insulating boards, magnesia-based insulating boards, magnesia-olivine-based insulating boards, and coatings such as magnesia-based or magnesia-chromium-based coatings.

Currently, castable refractory materials are also used as the lining for the intermediate ladle.

(4) Base Bricks

Embedded in the bottom of the intermediate ladle, these bricks are used for installing the ladle nozzle. Their material is typically high-alumina.

(5) Ladle Bottom

The bottom of the intermediate ladle, whose material is essentially the same as that of the working layer.

(6) Ladle cover

The ladle cover, which covers the ladle, serves to insulate and prevent steel spatter, among other functions. It is typically made of clay bricks or castable refractory materials.

(7) Slag retaining wall

This wall is constructed inside the ladle and can be either single-walled or double-walled. Whether single-wall or double-wall, the slag-blocking wall is designed to block slag, thereby improving the cleanliness of the molten steel. A molten steel filter can also be installed on it to further remove impurities from the molten steel. The material of the slag-blocking wall is typically high-quality blast furnace material, which can be constructed using bricks inside the intermediate ladle or manufactured as precast blocks and installed inside the intermediate ladle.

The main types of intermediate ladles include:

(1) High-temperature intermediate ladle

This intermediate ladle is designed for a specific metallurgical process, with a lining made of magnesium bricks, preheated to approximately 1500°C.

(2) Hot intermediate ladle

This is the most common type of intermediate ladle currently used in steel mills. It is lined with fired bricks, unfired bricks, or castable refractory materials and must be preheated to 800–1100°C before pouring.

(3) Cold ladle

This ladle uses insulating plates as lining and can be used without preheating before pouring.

The choice of ladle type and lining material depends on the steel grade being poured, the smelting method, baking conditions, and the capabilities of the steel mill.