What powders have in common
Powders are generally strongly hygroscopic and readily take up moisture again after drying. They are also light and easily airborne, which affects both equipment design and operation.
Batch consistency
For powders, consistent drying between batches often matters more than the capacity of a single batch. A batch rotary dryer charges, dries, cools and discharges in cycles with controlled time and temperature, which keeps the variation between batches small.
Additional requirements for aluminium powder
Aluminium powder is a combustible dust. Drying has to account for explosion protection and temperature control, avoiding dust accumulation and high-temperature conditions.
What to raise during selection
Hygroscopicity, whether the material becomes airborne easily and whether explosion protection is required should all be stated at the selection stage to avoid rework later.
References and Standards
- GB 15577—2018 Safety regulations for dust explosion prevention and protection[S]. Beijing: Standards Press of China, 2018. (in Chinese)
- AQ 4273—2016 Technical specification for safety of dust collection systems in dust explosion hazardous areas[S]. Beijing: China Coal Industry Publishing House, 2016. (in Chinese)
- Ministry of Emergency Management of the People's Republic of China. Safety regulations for dust explosion prevention in industrial and trade enterprises: Order No. 6[Z]. 2021. (in Chinese)
- Mujumdar A S. Handbook of Industrial Drying[M]. 4th ed. Boca Raton: CRC Press, 2014.
- Liu G W. Design Handbook of Drying Equipment[M]. Beijing: China Machine Press, 2009. (in Chinese)
- Liu X D, Li Z Y. Modern Drying Technology[M]. 3rd ed. Beijing: Chemical Industry Press, 2022. (in Chinese)