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Abstract
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.
| Nomenclature | ||
| c | = | Cohesion, kPa |
| MFR | = | Median to fine ratio (d50/d10) |
| CI | = | Compressibility index, % |
| Ci | = | Cohesive index |
| d10 | = | The particle size at the cumulative percentage of 10%, µm |
| d50 | = | The particle size at the cumulative percentage of 50%, µm |
| d90 | = | The particle size at the cumulative percentage of 90%, µm |
| Frb | = | Bulk powder Froude number (based on loose poured bulk density) |
| g | = | Acceleration due to gravity, m/s2 |
| HR | = | Hausner ratio |
| S | = | Shape factor |
| S-AoR | = | Static angle of repose, ° |
| wfo,b | = | Terminal settling velocity based on bulk powder, m/s |
| ρlb | = | Loose-poured bulk density, kg/m3 |
| ρt | = | Tapped density, kg/m3 |
| τ | = | Pre-shear stress, kPa |
| σ | = | Consolidation stress, kPa |
| φ | = | Angle of friction, ° |
| μ | = | Dynamic viscosity of air, Pa.s |
Acknowledgements
M/S Granutools supplier for the supply of Granutools equipment, Ref. PO No. TIET/CS/AA,/MED/19-20/19401, Dated 14.11.2019.
Correction Statement
This article has been corrected with minor changes. These changes do not impact the academic content of the article.