US Patent 6848197 Control of process humidity to produce large, porous particles

Spray dried particles having specified aerodynamic characteristics are produced by atomizing a liquid feed and contacting the liquid feed with a drying gas, such as, for example, air or nitrogen. The humidity of the drying gas is controlled to a value, expressed, for instance, as dew point, which is known to produce particles having a specified tap density or aerodynamic diameter. Particles having a volume median geometric diameter greater than about 5 microns and a tap density less than about 0.4 g/cm3 are preferred.