Bulk density, particle density and mean particle size of common materials used in bulk solids handling
Including portland cement, coal, iron powder, PVC, wheat flour
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Interactive Powder Properties & Silo Sizing Calculator
⚠️ ENGINEERING NOTICE & EDUCATIONAL DISCLAIMER: This interactive calculator is provided exclusively for preliminary estimation and educational purposes. It is not intended for detailed design or equipment procurement without certified vendor rating. No warranty, expressed or implied, is provided, and no liability is assumed.
Calculation Results
Bulk Porosity (\(\varepsilon\)): --
Req. Vol (\(V_{req}\)): --
Cylinder Vol (\(V_{cyl}\)): --
Cone Vol (\(V_{cone}\)): --
Total Vol (\(V_{tot}\)): --
Total Height (\(H_{tot}\)): --
Capacity Margin: --
Governing Physical Equations
The calculation of powder voidage and silo capacity relies on standard volumetric and mass relationships:
Porosity (Void Fraction):
\[\varepsilon = \left( 1 - \frac{\rho_{bulk}}{\rho_{particle}} \right) \times 100\%\]Total Available Silo Volume:
\[V_{total} = V_{cylinder} + V_{cone}\] \[V_{cylinder} = \frac{\pi \cdot D^2}{4} \cdot H_c\] \[V_{cone} = \frac{\pi \cdot H_{cone}}{12} \left( D^2 + D \cdot d_{outlet} + d_{outlet}^2 \right)\]Note: The interactive tool assumes a discharge outlet diameter of 15% of the silo diameter for cone volume calculation.
💡 Engineering Rules of Thumb: Powders
- Mass Flow vs. Funnel Flow: Ensure the cone angle (\(\alpha\)) is steep enough (typically > 60°) to achieve mass flow. Flat-bottom silos often suffer from stagnant material ("dead zones").
- Aeration Margin: Always provide a 15-20% volume margin. Fine powders (like flour or cement) can fluidize during filling, significantly increasing their apparent volume.
- Particle Size Variability: Smaller mean particle sizes usually lead to higher cohesion and lower bulk density (more air entrainment).
1. Reference Data Table
Note: These values are orders of magnitude only, varying depending on material grade and moisture content.
| Material | Mean particle size (\(\mu\text{m}\)) | Bulk density (\(\text{kg/m}^3\)) | Particle density (\(\text{kg/m}^3\)) |
|---|---|---|---|
| Alumina (Sandy) | 79 | 1040 | 3600 |
| Alumina (Calcined) | 66 | 750 | 3920 |
| Alumina (Hydrate) | 60 | 1110 | 2420 |
| Cement – Ordinary Portland | 14 | 1070 | 3060 |
| Coal (Pearls) | 10 000 | 690 | 1320 |
| Coal (Pulverized) | 84 | 393 | 1550 |
| Iron powder | 64 | 2380 | 5710 |
| PVC (Powder) | 90 | 615 | 990 |
| Wheat flour | 90 | 510 | 1470 |
Source: Pneumatic Conveying Design Guide, Mills