Impact of Laboratory Vacuum Contact Drying on Material Drying Rates and Physical Properties

In this study, the effect of different laboratory vacuum contact drying methods on the drying rates and physical properties of Lactose FastFlo 316, Avicel PH200, and an active pharmaceutical ingredient (API) were investigated. The influence of various types of dryers (conical screw, tray, and rotary drying on the drying) performance of Lactose FastFlo 316 was investigated. Conical screw drying was found to produce the best drying performance, but considerable attrition and agglomeration was observed. Tray drying was found to have the poorest drying performance with the greatest degree of particle agglomeration being observed when compared to rotary and conical screw drying. The impact of the various types of dryers on the particle size and size distribution of Avicel PH200 was found to be minimal when compared to the reference. For rotary drying, the effects of drying temperature, initial moisture content, median particle size input, vacuum pressure, and rotary speed on the drying rate and particle size distribution was assessed using the API. An increase in median particle size and rotary speed with a reduction in moisture content and vacuum pressure resulted in a decrease in overall drying times. An increase in rotary speed was found to decrease the particle size for both small and large input particle sizes as a result of attrition. In addition, to the drying equipment and conditions, the material properties are also important in determining whether attrition and/or agglomeration events will occur.