Calcium aluminate cement is mainly used as a binder for refractory castables and refractory injection materials. There are two main requirements for ordinary calcium aluminate cement:
(1) Appropriate setting time to ensure sufficient working time. Generally, the initial setting is required to be greater than 1h and the final setting is less than 8h. The shorter the time interval between the initial setting and the final setting, the better;
(2) Sufficient early strength, that is, it can reach 60%~70% of the strength specified by the cement label after one day of curing, and it can reach more than 90% after three days of curing.
In addition to the above two points, pure calcium aluminate cement is also required to have a certain degree of refractoriness and good workability to meet construction requirements and high temperature use requirements.
Medium and low-grade refractory castables, such as clay-based, high-aluminum castables, use ordinary calcium aluminate cement as a binder. High-grade refractory castables, such as corundum, mullite, chromium-containing corundum, corundum-spinel and other castables use pure calcium aluminate cement as a binder. The addition amount of calcium aluminate cement for ordinary refractory castables is 10%~20%, the addition amount of low cement refractory castables is 5%~7%, and the addition amount of ultra-low cement castables is less than 3%.
Among unshaped refractories, castables with calcium aluminate cement as binder are widely used.
(1) The use temperature of the clay castable is 1300-1450 degrees, and it is generally used as the lining of the preheating zone of the rolling furnace, various heat treatment furnaces, boilers, shaft kilns and rotary kilns.
(2) The use temperature of the high-alumina castable is 1400-1550 degrees, which can be used for the lining and burner of various heat treatment furnaces. Electric furnace tapping groove, high temperature section of lime shaft kiln, rotary kiln kiln head, power plant boiler lining.
(3) The use temperature of corundum castable is 1500-1650 degrees, mainly used for the lining of various high-temperature furnaces and high-temperature components to buy molten steel vacuum degassing equipment for dipping tubes, spray metallurgy and argon blowing integral spray guns Lining body, triangular area lining body of electric furnace roof, LF furnace cover, high temperature wear-resistant lining body of catalytic cracking reactor in petrochemical industry, etc.
