(703b) Characterization and Mitigation of Stick-Slip in Pharmaceutical Powders

Consistent powder flow is an important property for process control of pharmaceutical unit operations like milling and die filling of tablet presses. In literature, stick-slip is identified as one of the possible mechanisms for intermittent powder flow. In large material hoppers, stick-slip can also result in silo vibrations commonly referred to as silo quaking and honking. These silo vibrations can have major impact on the structural integrity of the silo as well as the surrounding environment. In literature, stick-slip is well documented for stiff particles of high sphericity. However, the literature on characterizing stick-slipfor pharmaceutical powders and providing potential mitigation strategies is terse. The objectives of the present work are to:

• Develop a method for measurement and prediction of stick-slip using bulk solid properties
• Discuss some of the common pitfalls of using ring shear tester data for characterization of stick-slip without additional processing
• Provide strategies to mitigate the stick-slip and
• Present experimental results showing the effectiveness of these mitigation strategies