Baking and Technical Requirements of Refractory Cement

Refractory cement refers to cement with a refractoriness of not less than 1580°C. Refractory cement is a hydraulic cementitious material made from bauxite and limestone as raw materials. It is fired into clinker with calcium aluminate as the main component and an alumina content of about 50%, and then ground. According to different compositions, it can be divided into aluminate refractory cement, low calcium aluminate refractory cement, etc. Refractory cement can be used to bind various refractory aggregates (such as corundum, burned high-alumina clay, etc.) to make refractory castables, refractory mortars, or refractory concrete, and can be used as linings for cement rotary kilns and other industrial kilns.

When baking refractory cement furnace lining, the following matters must be paid attention to

1. At the normal temperature 350℃ stage, local bursting is most likely to occur, so special attention should be paid to slow baking. If a large amount of steam still emerges after insulation at 350℃, the heating rate should still be slowed down.

2. Under conditions where ventilation is poor and water vapor cannot be easily discharged, the heat preservation time should be appropriately extended.

3. When baking with heavy oil, be careful not to spray heavy oil on the surface of the furnace lining to prevent local bursting.

4. When baking with firewood, direct contact with the flame often causes excessive local heating and should be protected.

5. The newly poured refractory cement must be baked for at least 3 days.

6. The refractory cement furnace lining should also be cooled slowly to avoid forced ventilation.

Technical requirements for refractory cement

1. Refractory cement fineness: The finer the cement particles, the larger the specific surface area, the faster and more complete the hydration reaction, and the higher the early and later strength. National regulations: The specific surface area should be greater than 300m²/kg, otherwise it will be unqualified.

2. Refractory cement setting time: To ensure that there is sufficient time to complete various processes such as mixing, transportation, and molding during construction, the initial setting time of cement should not be too short; after construction is completed, it is hoped that the cement can harden as soon as possible and produce strength, so The final setting time should not be too long. The initial setting time of refractory cement shall not be earlier than 45 minutes, and the final setting time shall not be later than 390 minutes.

3. Volume stability of refractory cement: The uniformity of volume changes of cement slurry during the setting and hardening process is called the volume stability of cement. If the volume change is uneven, the volume stability is poor, which may easily cause warping and cracking, reduce the quality of the project, and even cause accidents.