What are the Requirements for the Thickness of the Castable Lining for the Ladle?

The ladle is a crucial piece of equipment in the casting process, used to load and transport high-temperature molten iron. However, due to the unique operating environment, it often faces severe wear and high-temperature corrosion, resulting in a short lifespan. Therefore, improving the lifespan of the ladle's lining refractory castable is of great practical significance.

Thickness of the Ladle's Refractory Castable Lining

A ladle consists of a shell and the refractory lining. The shell is riveted and welded from steel plates, while the lining consists of a working layer and a coating layer. The working layer is cast using high-temperature resistant refractory castables. The thickness of the refractory castable in ladles is 100-150mm for the working lining and 10-15mm for the coating layer.

Current Status and Problems of Ladle Refractory Castable Linings

When molten iron is transported in ladles, the ladle lining is subjected to high temperatures, thermal shock, mechanical wear, and chemical corrosion from slag and iron. During pouring, the erosion is further exacerbated on the impact surface. Furthermore, ladles operate in alternating high and low temperature conditions; the longer the intervals, the more severe the lining damage. Therefore, ladle linings should generally be made of refractory materials that are corrosion-resistant, high-strength, and thermal shock-resistant.

During ladle processing, the molten iron experiences vigorous movement, exacerbating lining erosion. Foundry deslagging agents are used to aggregate and bind slag on the surface of the molten iron. During the deslagging process, the slag becomes sticky and easily adheres to the lining, making it difficult to clean. Combined with the erosion caused by the agitated molten iron and the temperature fluctuations caused by intermittent operation, damage to the ladle lining, particularly at the slag line, is exacerbated, as shown in the figure.

Selection of refractory castables for ladle lining and repair

(1) The ladle working layer is cast with low-moisture, low-cement alumina-based materials. It has the following advantages and characteristics:

• ①Excellent anti-stripping ability.

• ②Excellent cold and hot strength.

• ③Resistance to thermal shock.

(2) The ladle working layer repair material uses phosphoric acid as a binder and alumina-based repair refractory materials. This product has high plasticity and is more suitable for repairing thinner layers. It also contains organic fibers and is easier to dry. It has the following advantages and characteristics:

• ①Resistance to thermal shock.

• ②Abrasion resistance and corrosion resistance.

• ③Applicable to ferrous and non-ferrous metals.

(3) The ladle coating layer uses carbon-containing repair refractory mud. This material has good adhesion and can be used for thin layer repairs of molten iron contact areas such as ladles in the foundry industry. It can also be used as a coating material for ladles. It effectively improves the slag sticking problem of the ladle. It has the following advantages and characteristics:

• ① Ready to use, easy to apply.

• ② Excellent bonding properties.

• ③ Excellent resistance to slag sticking.

Repair of molten iron ladle

(1) Repair method of molten iron ladle

The molten iron ladle that needs to be repaired should be cooled for 4 hours first, then the sticky slag around the slag line of the molten iron ladle should be cleaned and repaired using phosphoric acid as a binder for 4 hours. After the repair is completed, the surface is coated with carbon-containing repair refractory mud and then baked for 2 hours before it can be put into production for standby use.

(2) Unpacking process of molten iron ladle

Unpack the molten iron ladle that needs to be relined with castables. First, soak the molten iron ladle in water and cool it for 8 hours. After the molten iron ladle is completely cooled, unpack the molten iron ladle. After cleaning, the molten iron ladle castable can be used for pouring. After pouring is completed, dry it in the shade for 48 hours to ensure that the moisture in the molten iron ladle is completely evaporated. After drying in the shade, apply carbon-containing repair refractory mud on the surface and finally bake it for 72 hours before it can be put into production for standby use.