Raw Material-Based Hot Air Temperature Adjustment Standards for Fired Brick Green Body Drying
Hot air temperature adjustment is the core foundation of fired brick drying process. The inlet hot air temperature of the artificial drying chamber cannot adopt a unified standard; it must be dynamically adjusted according to the physical properties and process requirements of different brick raw materials. Targeted temperature matching is the premise to ensure stable drying quality, avoid drying cracks and brick resurgence, and improve the yield of finished bricks.
For conventional lightweight and low-sensitivity raw materials, clay hollow bricks and fly ash fired bricks apply a low-temperature drying scheme with a hot air range of 60℃ to 80℃. These two types of green bricks have loose internal structure and fast water permeability. Low-temperature and slow artificial drying can realize uniform internal and external dehydration, effectively preventing quality defects such as surface crusting and invisible internal micro-cracks caused by excessive high temperature and rapid drying.
For shale and coal gangue raw materials widely used in industrial brick making, the hot air temperature is classified and controlled based on brick structure and drying sensitivity coefficient. When the sensitivity coefficient is 1 to 2, solid structuredshale and coal gangue fired bricks require a higher drying temperature of 100℃ to 120℃ to accelerate the migration of internal bound water. In contrast, hollow bricks of the same raw materials adopt a moderate temperature of 80℃ to 100℃, adapting to the porous hollow structure to avoid structural damage caused by uneven heating.
High-stability raw materials with a drying sensitivity coefficient below 1 support high-temperature rapid drying, with the drying hot air temperature adjustable to 120℃-125℃. This parameter can greatly compress the drying cycle while maintaining zero cracking and zero resurgence, which is very suitable for large-scale and high-efficiency continuous production of modern brick factories.
To cooperate with accurate temperature adjustment, supporting process parameters must be strictly matched. The standard exhaust gas temperature of the drying chamber is 35℃-45℃, with relative humidity controlled at 90%-95% and indoor air flow rate maintained at 1.5-4.5m/s. Meanwhile, controlling the mud heating temperature at 45℃-60℃ through hot water or steam stirring can optimize the initial moisture uniformity of green bricks and further stabilize the temperature drying effect.
It is worth noting that a key quality control threshold must be guaranteed in actual operation: the temperature of green bricks entering the drying chamber must be higher than the humidity temperature of kiln outlet exhaust gas. This rule completely solves the problem of green brick resurgence caused by temperature difference and ensures the dimensional accuracy and structural strength of all types of fired bricks after drying.
