Explosion protection for high-containment impact milling systems
Today's finer particle sizes along with increasing powder toxicity and other hazards make it more important than ever not only to contain powders during impact milling, but to provide explosion protection for these milling systems. This article describes explosion protection methods for high-containment impact milling systems that handle fine and hazardous powders.
Impact milling is commonly used to produce fine powders, such as pharmaceuticals and chemicals, with a mean particle size of about 15 to 25 microns. Not only are the milled powders fine enough to pose respiratory hazards to workers, but impact mills produce sparks that increase the risk of powder explosions. High-impact mills, such as universal, cage, and pin mills, produce high-energy sparks that can ignite most fine powders. If static is present, even low-impact mills such as cone mills can pose an ignition hazard for a powder with a low minimum ignition energy [MIE].