The first step of castable selection is defining the service temperature and its fluctuation range. Standard high-alumina castables suit 1300–1500℃, corundum and corundum-mullite grades cover 1500–1700℃, while lightweight insulating castables are used for the insulating layer without direct media contact. Beyond temperature, confirm the atmosphere (oxidizing/reducing), media (hot metal, slag, alkali, acid gases) and abrasion intensity.
The second step determines the aggregate system. High-alumina offers the best cost-performance; corundum gives high strength, abrasion and temperature resistance; mullite excels in thermal-shock stability; SiC leads in wear and slag resistance. Grain sizing governs placement and density — choose suppliers with stable quality and rational grading.
The third step selects the binder. Low-cement and ultra-low-cement castables are the mainstream for hot working linings due to high strength and good high-temperature properties; water-glass binders suit fast drying; phosphate binders suit zones demanding strength at high temperature. Water addition directly controls strength and porosity — always follow the datasheet.
The fourth step evaluates placement: cast in place, self-flow pumping, ramming or gunning, each matched to a material form. The fifth balances economy — higher temperature rating is not always better; zone-based selection is often more cost-effective than one grade for the whole furnace.
Unsure about selection? Send us your service conditions (temperature, media, zone, maintenance cycle) and Songrui will recommend grades and trial options free of charge.
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