What are Some Selection Tips for Using Refractory Castables?

With the increasingly widespread application of refractory castables, choosing the right material or specifications requires specific methods and expertise.

RS Kiln Refractory Factory classifies refractory castables into neutral, acidic, and basic types, as well as heavy and light grades. Heavy refractory castables are generally used in the working layer, while light refractory castables are used in the insulation layer for heat preservation.

For neutral high-alumina series refractory castables, the specific specifications are determined based on the temperature and erosion conditions of the furnace lining. For temperatures below 1200℃, clay castables are sufficient. For temperatures exceeding 1250℃, high-alumina castables are required. For temperatures exceeding 1350℃, corundum refractory castables are chosen. For extremely corrosive conditions, chromium corundum castables are required. For severe wear, abrasion-resistant refractory castables are necessary. The neutral material should be stored for 6 months. It is important to keep the raw materials and binders separate.

For castings used in acidic atmospheres, acidic castings should be selected. Acidic castings are bonded by two types of binders: water glass and phosphoric acid. For acidic atmospheres with temperatures not exceeding 1250℃, water glass-bonded acidic castings are sufficient. For higher temperatures, phosphoric acid-bonded acid-resistant castings should be chosen.

For castings used in alkaline atmospheres, magnesia-based refractory castings should be selected. For applications requiring corrosion and abrasion resistance, magnesia-alumina or magnesia-chromium refractory castings should be used. For higher temperatures, high-density or high-content magnesia-based castings can be used. However, magnesia-based castings must be stored carefully and should not be stored outdoors, as they cannot come into contact with water and will pulverize.

For castings used in insulation layers, the choice also depends on the temperature. For lower temperatures, general lightweight insulating castings are sufficient. If the temperature is too high, lightweight high-alumina or alumina hollow sphere lightweight castable should be used as the insulation layer. Care must be taken when storing lightweight castable; it should not be placed with highly corrosive materials, otherwise it will damage the lightweight castable.

If the furnace outer shell has low requirements, double-layer insulation should be used, which involves first ceramic fiber and then lightweight insulating castable, or ceramic fiber blocks can be used directly. However, if there are weight requirements for the insulation area, a specific gravity of 0.6-0.8 should be used for the insulation layer. If the insulating castable is used directly in the working layer of the flue, a lightweight castable with a specific gravity of 1.3-1.5 should be used as the inner lining. For refractory atmospheres, lightweight acid-resistant castable should be used as the inner lining.

In short, regardless of the type of refractory castable chosen, the selection must be based on the application, the lining atmosphere, and the temperature.