An investigation into static angle of repose using pharmaceutical powders

Physical and flow property tests were carried out on eight pharmaceutical powders. The results obtained from heap analysis and shear cell testing have been compared. A relationship to represent the static angle of repose has been developed using a bulk powder-based Froude number and fine size. The experimental results and predictions for a range of bulk properties have shown that the values of static angle of repose decrease with an increase in the value of bulk powder Froude number, increase in particle shape factor and decrease in the median to fine ratio. Out of all the dimensionless parameter groupings, the particle shape factor strongly influences the static angle of repose, as indicated by its larger absolute value of the exponent in the power function format relationship. The relationship can be used as a techno-economic optimization tool for particle processing/synthesis while maintaining the desired powder flowability.